No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Targeting CAFs to overcome anticancer therapeutic resistance
Abstract
The view of cancer as a tumor cell-centric disease is now replaced by our understanding of the interconnection and dependency of tumor stroma. Cancer-associated fibroblasts (CAFs), the most abundant stromal cells in the tumor microenvironment (TME), are involved in anticancer therapeutic resistance. As we unearth more solid evidence on the link between CAFs and tumor progression, we gain insight into the role of CAFs in establishing resistance to cancer therapies. Herein, we review the origin, heterogeneity, and function of CAFs, with a focus on how CAF subsets can be used as biomarkers and can contribute to therapeutic resistance in cancer. We also depict current breakthroughs in targeting CAFs to overcome anticancer therapeutic resistance and discuss emerging CAF-targeting modalities.
... No specific markers exist for CAFs, although elevated alpha-smooth muscle actin (aSMA) expression is considered indicative of activated CAFs (4). Exhibiting enhanced proliferative and migratory capabilities, CAFs significantly influence tumor progression (5). Numerous studies have established the critical role of CAFs in solid tumors such as pancreatic, breast, colon, gastric, and liver malignancies (6)(7)(8)(9)(10). ...
... The significance of CAFs in tumor progression and drug resistance is increasingly acknowledged, making them a focal point of recent research. Promisingly, several CAF-targeting therapies have entered clinical trials (5,13). ...
... One of the primary challenges lies in the heterogeneity of CAFs, as they can originate from various cell types and exhibit diverse phenotypes and functions. This complexity may hinder the development of specific CAF-targeted therapies and could necessitate the identification of common signaling pathways or markers that can be targeted across different CAF subpopulations (4,5). Cancer boasts a multifaceted biological composition and structure, encompassing cancerous cells, stromal cells, and the extracellular matrix (49). ...
Hematologic malignancies comprise a diverse range of blood, bone marrow, and organ-related disorders that present significant challenges due to drug resistance, relapse, and treatment failure. Cancer-associated fibroblasts (CAFs) represent a critical component of the tumor microenvironment (TME) and have recently emerged as potential therapeutic targets. In this comprehensive review, we summarize the latest findings on the roles of CAFs in various hematologic malignancies, including acute leukemia, multiple myeloma, chronic lymphocytic leukemia, myeloproliferative neoplasms, and lymphoma. We also explore their involvement in tumor progression, drug resistance, and the various signaling pathways implicated in their activation and function. While the underlying mechanisms and the existence of multiple CAF subtypes pose challenges, targeting CAFs and their associated pathways offers a promising avenue for the development of innovative treatments to improve patient outcomes in hematologic malignancies.
... Normal fibroblasts are usually inhibit tumor formation while CAFs exhibit both promoting tumor phenotype and inhibiting tumor phenotype, and the former represents the majority of CAFs and involves in tumorigenesis, development, and resistance to treatment, while the inhibiting tumor phenotype can inhibit tumor proliferation and growth [13,28]. For example, CAFs in pancreatic cancer are divided into inhibiting tumors subsets and promoting tumors subsets according to their different effects on tumors. ...
... On the other hand, various factors secreted by CAFs can also promote tumor progression by regulating immune cells in TME [28]. For example, CAFs can inhibit natural killer (NK) cell function and the expression of NK receptors, perforin, and granzyme B by secreting cytokines, chemokines, and MMPs [71]. ...
... For example, CAFs can inhibit natural killer (NK) cell function and the expression of NK receptors, perforin, and granzyme B by secreting cytokines, chemokines, and MMPs [71]. Moreover, CAFs can promote the recruitment of monocytes and promote their transformation into M2 TAMs by releasing IL-8, IL-10, TGF-β, and CXCL12 [28,72,73]. CAFs can also recruit MDSCs, and activate monocyte MDSCs (M-MDSCs) through secreting CCL2 and IL-6 by CAFs and miR-21 derived from CAFs, and further activate the production of MDSCs [74][75][76]. ...
The tumor microenvironment (TME) is made up of cells and extracellular matrix (non-cellular component), and cellular components include cancer cells and non-malignant cells such as immune cells and stromal cells. These three types of cells establish complex signals in the body and further influence tumor genesis, development, metastasis and participate in resistance to anti-tumor therapy. It has attracted scholars to study immune cells in TME due to the significant efficacy of immune checkpoint inhibitors (ICI) and chimeric antigen receptor T (CAR-T) in solid tumors and hematologic tumors. After more than 10 years of efforts, the role of immune cells in TME and the strategy of treating tumors based on immune cells have developed rapidly. Moreover, ICI have been recommended by guidelines as first- or second-line treatment strategies in a variety of tumors. At the same time, stromal cells is another major class of cellular components in TME, which also play a very important role in tumor metabolism, growth, metastasis, immune evasion and treatment resistance. Stromal cells can be recruited from neighboring non-cancerous host stromal cells and can also be formed by transdifferentiation from stromal cells to stromal cells or from tumor cells to stromal cells. Moreover, they participate in tumor genesis, development and drug resistance by secreting various factors and exosomes, participating in tumor angiogenesis and tumor metabolism, regulating the immune response in TME and extracellular matrix. However, with the deepening understanding of stromal cells, people found that stromal cells not only have the effect of promoting tumor but also can inhibit tumor in some cases. In this review, we will introduce the origin of stromal cells in TME as well as the role and specific mechanism of stromal cells in tumorigenesis and tumor development and strategies for treatment of tumors based on stromal cells. We will focus on tumor-associated fibroblasts (CAFs), mesenchymal stem cells (MSCs), tumor-associated adipocytes (CAAs), tumor endothelial cells (TECs) and pericytes (PCs) in stromal cells.
... In recent years, the role of the tumor microenvironment (TME) in tumor proliferation and drug resistance has garnered increasing attention. As primary stromal cells in the TME, cancer-associated fibroblasts (CAFs) play a crucial role in tumor proliferation, invasion, migration, and drug resistance by producing soluble factors via paracrine mechanisms [2,3]. For example, the secretion of transforming growth factor (TGF)-β leads to cisplatin resistance in esophageal cancer, while paracrine exosomes affect the Wnt/β-catenin pathway in colorectal cancer, resulting in resistance to oxaliplatin and 5-fluorouracil [3,4]. ...
... As primary stromal cells in the TME, cancer-associated fibroblasts (CAFs) play a crucial role in tumor proliferation, invasion, migration, and drug resistance by producing soluble factors via paracrine mechanisms [2,3]. For example, the secretion of transforming growth factor (TGF)-β leads to cisplatin resistance in esophageal cancer, while paracrine exosomes affect the Wnt/β-catenin pathway in colorectal cancer, resulting in resistance to oxaliplatin and 5-fluorouracil [3,4]. Therefore, it is essential to further explore the paracrine components and their mechanisms in GC and CAFs. ...
... Targeting the intricate interactions between CAFs and tumor cells revolutionizes cancer treatment, offering new prospects for enhanced patient recovery. 10,31,[166][167][168][169] Therapeutic targeting focuses on mechanisms triggering CAF activation and associated signaling pathways. 121 Numerous signaling cascades significantly impact the biological activities of CAFs and the interplay between CAFs and cancer cells. ...
... The TME and downstream effectors of CAFs are under intensive investigation for potential new treatments. 166 Despite these advances, the versatile nature of CAFs, which can shift between different subtypes, presents a challenge in enhancing tumor control. Deep insights into the balance between tumorpromoting and restricting CAFs and their dynamic interactions in the TME are essential as they uncover potential targets. ...
The understanding of cancer has evolved significantly, with the tumor microenvironment (TME) now recognized as a critical factor influencing the onset and progression of the disease. This broader perspective challenges the traditional view that cancer is primarily caused by mutations, instead emphasizing the dynamic interaction between different cell types and physicochemical factors within the TME. Among these factors, cancer-associated fibroblasts (CAFs) command attention for their profound influence on tumor behavior and patient prognoses. Despite their recognized importance, the biophysical and mechanical interactions of CAFs within the TME remain elusive. This review examines the distinctive physical characteristics of CAFs, their morphological attributes, and mechanical interactions within the TME. We discuss the impact of mechanotransduction on CAF function and highlight how these cells communicate mechanically with neighboring cancer cells, thereby shaping the path of tumor development and progression. By concentrating on the biomechanical regulation of CAFs, this review aims to deepen our understanding of their role in the TME and to illuminate new biomechanical-based therapeutic strategies.
... Tumor-associated fibroblasts (CAF) is one of the key cell components in tumor microenvironment. It is formed by normal fibroblasts (NAF) under the action of cancer cells, and can regulate the proliferation, metastasis and drug resistance of cancer cells [24]. Existing studies have shown that cancer-associated fibroblasts (CAF) interact with lung cancer cells to obtain malignant tumors and therapeutic drug resistance through paracrine rings through EMT signals in the tumor microenvironment. ...
As a malignant tumor with high morbidity and mortality in the world, the treatment of non-small cell lung cancer is still facing great challenges. Although new breakthroughs have been made in recent years and great progress has been made in chemotherapy and targeted therapy, the five-year survival rate of most NSCLC patients is still at a low level. The emergence of drug resistance is one of the important factors affecting the therapeutic effect and survival rate of patients. PRMT5 (protein arginine methyltransferase 5), as a type II arginine methyltransferase, plays an important role in cancer cell proliferation, differentiation, apoptosis and tumorigenesis. At present, people pay more and more attention to the research on the mechanism of PRMT5 in tumor drug resistance. In this review, we summarize the mechanism of PRMT5 in chemotherapy resistance of non-small cell lung cancer and discuss potential strategies to avoid or overcome chemotherapy resistance.
... CAFs secrete diverse cytokines, growth factors, and exosomes, through which they reciprocally interact with tumor cells, as well as other cell types, within the TME [11,12]. These multi-network interactions promote the malignant progression of tumors, including angiogenesis, chronic inflammation, immune suppression, and invasion and metastasis [13,14]. CAFs possess a strong ability to build and remodel the ECM through their contractility and production of ECM components (including collagens and fibronectin) and remodeling enzymes (such as matrix-degrading and -crosslinking enzymes) [15]. ...
Simple Summary: Invasion of cancer into surrounding tissues is crucial for it to spread to other parts of the body, a process known as metastasis. The characteristics of cancer cells within tumors are significantly influenced by the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are the primary cellular component of the TME and play a pivotal role in cancer progression, including growth, invasion, metastasis, therapy resistance, and immune suppression. Numerous factors mediating interactions between CAFs and cancer cells have been identified, such as growth factors, cytokines, and extracellular vesicles. Recent studies have highlighted the importance of direct contact between CAFs and cancer cells in facilitating cancer invasion and metastasis to distant organs. This review summarizes recent findings on the molecular and cellular mechanisms underlying this direct heterocellular adhesion, providing insights into how CAFs drive cancer invasion and metastasis. Abstract: Cancer invasion is a requisite for the most malignant progression of cancer, that is, metasta-sis. The mechanisms of cancer invasion were originally studied using in vitro cell culture systems, in which cancer cells were cultured using artificial extracellular matrices (ECMs). However, conventional culture systems do not precisely recapitulate in vivo cancer invasion because the phenotypes of cancer cells in tumor tissues are strongly affected by the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are the most abundant cell type in the TME and accelerate cancer progression through invasion, metastasis, therapy resistance, and immune suppression. Thus, the reciprocal interactions between CAFs and cancer cells have been extensively studied, leading to the identification of factors that mediate cellular interactions, such as growth factors, cytokines, and extracellular vesicles. In addition, the importance of direct heterocellular adhesion between cancer cells and CAFs in cancer progression has recently been elucidated. In particular, CAFs are directly associated with cancer cells, allowing them to invade the ECM and metastasize to distant organs. In this review, we summarize the recent progress in understanding the molecular and cellular mechanisms of the direct heterocellular interaction in CAF-led cancer invasion and metastasis, with an emphasis on gastric cancer.
... Nanocarriers produced from hybrid nanomaterials, such as gold core and silver shell nanoparticles (Ag@AuNPs), have been shown to inhibit CAFs by promoting tumor growth, leading to reduced metastasis in animal models. 181 These nanoparticles alter gene expression related to cancer invasion and metastasis, effectively immobilizing CAFs by inducing lipid production. 182 However, targeting CAFs is challenging because of their diversity and the difficulty in identifying specific markers and subpopulations. ...
Typical physiological characteristics of tumors, such as weak acidity, low oxygen content, and upregulation of certain enzymes in the tumor microenvironment (TME), provide survival advantages when exposed to targeted attacks by drugs and responsive nanomedicines. Consequently, cancer treatment has significantly progressed in recent years. However, the evolution and adaptation of tumor characteristics still pose many challenges for current treatment methods. Therefore, efficient and precise cancer treatments require an understanding of the heterogeneity degree of various factors in cancer cells during tumor evolution to exploit the typical TME characteristics and manage the mutation process. The highly heterogeneous tumor and infiltrating stromal cells, immune cells, and extracellular components collectively form a unique TME, which plays a crucial role in tumor malignancy, including proliferation, invasion, metastasis, and immune escape. Therefore, the development of new treatment methods that can adapt to the evolutionary characteristics of tumors has become an intense focus in current cancer treatment research. This paper explores the latest understanding of cancer evolution, focusing on how tumors use new antigens to shape their “new faces”; how immune system cells, such as cytotoxic T cells, regulatory T cells, macrophages, and natural killer cells, help tumors become “invisible”, that is, immune escape; whether the diverse cancer-associated fibroblasts provide support and coordination for tumors; and whether it is possible to attack tumors in reverse. This paper discusses the limitations of targeted therapy driven by tumor evolution factors and explores future strategies and the potential of intelligent nanomedicines, including the systematic coordination of tumor evolution factors and adaptive methods, to meet this therapeutic challenge.
... CAFs secrete diverse cytokines, growth factors, and exosomes, through which they reciprocally interact with tumor cells, as well as other cell types, within the TME [11,12]. These multi-network interactions promote the malignant progression of tumors, including angiogenesis, chronic inflammation, immune suppression, and invasion and metastasis [13,14]. CAFs possess a strong ability to build and remodel the ECM through their contractility and production of ECM components (including collagens and fibronectin) and remodeling enzymes (such as matrix-degrading and -crosslinking enzymes) [15]. ...
Simple Summary
Invasion of cancer into surrounding tissues is crucial for it to spread to other parts of the body, a process known as metastasis. The characteristics of cancer cells within tumors are significantly influenced by the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are the primary cellular component of the TME and play a pivotal role in cancer progression, including growth, invasion, metastasis, therapy resistance, and immune suppression. Numerous factors mediating interactions between CAFs and cancer cells have been identified, such as growth factors, cytokines, and extracellular vesicles. Recent studies have highlighted the importance of direct contact between CAFs and cancer cells in facilitating cancer invasion and metastasis to distant organs. This review summarizes recent findings on the molecular and cellular mechanisms underlying this direct heterocellular adhesion, providing insights into how CAFs drive cancer invasion and metastasis.
Abstract
Cancer invasion is a requisite for the most malignant progression of cancer, that is, metastasis. The mechanisms of cancer invasion were originally studied using in vitro cell culture systems, in which cancer cells were cultured using artificial extracellular matrices (ECMs). However, conventional culture systems do not precisely recapitulate in vivo cancer invasion because the phenotypes of cancer cells in tumor tissues are strongly affected by the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are the most abundant cell type in the TME and accelerate cancer progression through invasion, metastasis, therapy resistance, and immune suppression. Thus, the reciprocal interactions between CAFs and cancer cells have been extensively studied, leading to the identification of factors that mediate cellular interactions, such as growth factors, cytokines, and extracellular vesicles. In addition, the importance of direct heterocellular adhesion between cancer cells and CAFs in cancer progression has recently been elucidated. In particular, CAFs are directly associated with cancer cells, allowing them to invade the ECM and metastasize to distant organs. In this review, we summarize the recent progress in understanding the molecular and cellular mechanisms of the direct heterocellular interaction in CAF-led cancer invasion and metastasis, with an emphasis on gastric cancer.
... The association between CAFs and chemoresistance and radiation resistance has been previously established (49,50). Ren et al. found that HPV16/18 infection in cervical cancer cells activates the IL-6/STAT3 pathway through the E6 protein, thus leading to the secretion of IL-6 into the extracellular matrix. ...
Cervical carcinoma is the most prevalent gynecology malignant tumor and ranks as the fourth most common cancer worldwide, thus posing a significant threat to the lives and health of women. Advanced and early-stage cervical carcinoma patients with high-risk factors require adjuvant treatment following surgery, with radiotherapy being the primary approach. However, the tolerance of cervical cancer to radiotherapy has become a major obstacle in its treatment. Recent studies have demonstrated that radiation resistance in cervical cancer is closely associated with DNA damage repair pathways, the tumor microenvironment, tumor stem cells, hypoxia, cell cycle arrest, and epigenetic mechanisms, among other factors. The development of tumor radiation resistance involves complex interactions between multiple genes, pathways, and mechanisms, wherein each factor interacts through one or more signaling pathways. This paper provides an overview of research progress on an understanding of the mechanism underlying radiation resistance in cervical cancer.
... Additionally, responses of most LCAs to the chemotherapeutic and targeted drugs were decreased compared with LCOs (Fig. 7b, Supplementary Fig. 9b), similar with the previous study 25 . These differences may be caused by the tumor microenvironments existed in LCAs, which may reflect the real responses of tumors with microenvironment to drugs [59][60][61] . Then, the cell viability consistency across parallel experiments was assessed. ...
Cancer models play critical roles in basic cancer research and precision medicine. However, current in vitro cancer models are limited by their inability to mimic the three-dimensional architecture and heterogeneous tumor microenvironments (TME) of in vivo tumors. Here, we develop an innovative patient-specific lung cancer assembloid (LCA) model by using droplet microfluidic technology based on a microinjection strategy. This method enables precise manipulation of clinical microsamples and rapid generation of LCAs with good intra-batch consistency in size and cell composition by evenly encapsulating patient tumor-derived TME cells and lung cancer organoids inside microgels. LCAs recapitulate the inter- and intratumoral heterogeneity, TME cellular diversity, and genomic and transcriptomic landscape of their parental tumors. LCA model could reconstruct the functional heterogeneity of cancer-associated fibroblasts and reflect the influence of TME on drug responses compared to cancer organoids. Notably, LCAs accurately replicate the clinical outcomes of patients, suggesting the potential of the LCA model to predict personalized treatments. Collectively, our studies provide a valuable method for precisely fabricating cancer assembloids and a promising LCA model for cancer research and personalized medicine.
... Increasing evidence suggests that CAFs mediate chemoresistance in OC [13]. Therefore, CAFs represent a promising therapeutic target for the treatment of OC [14]. ...
Background
To establish a prognostic risk profile for ovarian cancer (OC) patients based on cancer-associated fibroblasts (CAFs) and gain a comprehensive understanding of their role in OC progression, prognosis, and therapeutic efficacy.
Methods
Data on OC single-cell RNA sequencing (scRNA-seq) and total RNA-seq were collected from the GEO and TCGA databases. Seurat R program was used to analyze scRNA-seq data and identify CAFs clusters corresponding to CAFs markers. Differential expression analysis was performed on the TCGA dataset to identify prognostic genes. A CAF-associated risk signature was designed using Lasso regression and combined with clinicopathological variables to develop a nomogram. Functional enrichment and the immune landscape were also analyzed.
Results
Five CAFs clusters were identified in OC using scRNA-seq data, and 2 were significantly associated with OC prognosis. Seven genes were selected to develop a CAF-based risk signature, primarily associated with 28 pathways. The signature was a key independent predictor of OC prognosis and relevant in predicting the results of immunotherapy interventions. A novel nomogram combining CAF-based risk and disease stage was developed to predict OC prognosis.
Conclusion
The study highlights the importance of CAFs in OC progression and suggests potential for innovative treatment strategies. A CAF-based risk signature provides a highly accurate prediction of the prognosis of OC patients, and the developed nomogram shows promising results in predicting the OC prognosis.
... Thus, C1r and/or its downstream molecules may participate in shaping the TME. CAFs and M2 macrophages play an essential role in TME and have become prominent targets for tumor prevention and treatment [33][34][35]. CAFs have multiple distinct subtypes, and the proportions of these various subtypes differ amongst tumor tissues, as each have different functions. Notably, the inflammatory CAFs or complement-secreting CAFs exhibit high expression levels of multiple complement components which may be involved in inflammation, and/or recruitment of myeloid-derived suppressor cells (MD-SCs) [36][37][38][39]. ...
Background:
Mounting evidence indicates that complement components play a crucial role in cancer progression. Recent findings indicate that certain complement components display a significant rise in expression within esophageal squamous cell carcinoma (ESCC). However, the specific tumorigenic functions of these components remain unclear. This study focuses on investigating the expression pattern of C1r, elucidating a role for C1r in ESCC, as well as exploring underlying mechanisms controlled by C1r.
Methods:
The expression of C1r in ESCC tissues, malignant epithelial cells, and its relationship with survival were analyzed using the Gene Expression Omnibus (GEO) database and tissue microarrays. Single-cell RNA sequencing (scRNA-seq) was used to study the expression of C1r in malignant epithelial cells. C1r knockdown or C1r overexpression in cultured ESCC cells were used to assess the effects of C1r on proliferation, migration, invasion, cell-matrix adhesion, apoptosis, and growth of xenografted tumors in immunocompromised (nude) mice. Western blotting was used to detect the expression of MMP-1 and MMP-10 in C1r knockdown or C1r overexpressing ESCC cells.
Results:
C1r was highly expressed in ESCC tissues, malignant epithelial cells, and cultured ESCC cell lines. High C1r expression indicated a poor prognosis. Knockdown of C1r significantly suppressed the proliferation, migration, invasion, cell-matrix adhesion, and promoted apoptosis in cultured ESCC cells. Additionally, knockdown of C1r markedly inhibited tumor growth in nude mice. Overexpression of C1r had the opposite effects. C1r induced the expression of MMP-1 and MMP-10.
Conclusions:
C1r is highly expressed in ESCC and promotes the progression of this tumor type. Our findings suggest that C1r may serve as a novel prognostic biomarker and therapeutic target in ESCC.
... Nevertheless, the TME's main core is made up of CAFs. By modifying the extracellular matrix to create thick fibrous stroma, CAFs can reduce DC proliferation and migration, draw MDSCs, and impede T cell invasion [38]. TAMs are divided into pro-tumorigenic M2 and anti-tumorigenic M1 (classically activated) phenotypes [39]. ...
Citation: Katopodi, T.; Petanidis, S.; Grigoriadou, E.; Anestakis, D.; Charalampidis, C.; Chatziprodromidou, I.; Floros, G.; Eskitzis, P.; Zarogoulidis, P.; Koulouris, C.; et al. Immune Specific and Tumor-Dependent mRNA Vaccines for Cancer Immunotherapy: Reprogramming Clinical Translation into Tumor Editing Therapy. Pharmaceutics 2024, 16, 455. Abstract: Extensive research into mRNA vaccines for cancer therapy in preclinical and clinical trials has prepared the ground for the quick development of immune-specific mRNA vaccines during the COVID-19 pandemic. Therapeutic cancer vaccines based on mRNA are well tolerated, and are an attractive choice for future cancer immunotherapy. Ideal personalized tumor-dependent mRNA vaccines could stimulate both humoral and cellular immunity by overcoming cancer-induced immune suppression and tumor relapse. The stability, structure, and distribution strategies of mRNA-based vaccines have been improved by technological innovations, and patients with diverse tumor types are now being enrolled in numerous clinical trials investigating mRNA vaccine therapy. Despite the fact that therapeutic mRNA-based cancer vaccines have not yet received clinical approval, early clinical trials with mRNA vaccines as monotherapy and in conjunction with checkpoint inhibitors have shown promising results. In this review, we analyze the most recent clinical developments in mRNA-based cancer vaccines and discuss the optimal platforms for the creation of mRNA vaccines. We also discuss the development of the cancer vaccines' clinical research, paying particular attention to their clinical use and therapeutic efficacy, which could facilitate the design of mRNA-based vaccines in the near future.
... TGFβ also drives glycolytic metabolism in fibroblasts 62-64 , uncovering a potential role for TGFβ in glyCAF biogenesis, although this warrants further investigation. This work highlights the importance of considering the functional features of CAFs when developing therapeutic strategies targeting the tumor microenvironment 65 . Accordingly, reprogramming the glycolytic properties of CAFs by inhibiting the GLUT1 glucose transporter led to decreased Cxcl16 expression in the glyCAF and increased infiltration of cytotoxic CD8 + T cells into the tumor, independent of cancer cell-intrinsic metabolism and other immune cells in the TME. ...
T cell-based immunotherapies have exhibited promising outcomes in tumor control; however, their efficacy is limited in immune-excluded tumors. Cancer-associated fibroblasts (CAFs) play a pivotal role in shaping the tumor microenvironment and modulating immune infiltration. Despite the identification of distinct CAF subtypes using single-cell RNA-sequencing (scRNA-seq), their functional impact on hindering T-cell infiltration remains unclear, particularly in soft-tissue sarcomas (STS) characterized by low response rates to T cell-based therapies. In this study, we characterize the STS microenvironment using murine models (in female mice) with distinct immune composition by scRNA-seq, and identify a subset of CAFs we termed glycolytic cancer-associated fibroblasts (glyCAF). GlyCAF rely on GLUT1-dependent expression of CXCL16 to impede cytotoxic T-cell infiltration into the tumor parenchyma. Targeting glycolysis decreases T-cell restrictive glyCAF accumulation at the tumor margin, thereby enhancing T-cell infiltration and augmenting the efficacy of chemotherapy. These findings highlight avenues for combinatorial therapeutic interventions in sarcomas and possibly other solid tumors. Further investigations and clinical trials are needed to validate these potential strategies and translate them into clinical practice.
... CAFs are the most abundant cell type in the TME and are the center of cross-communication between various cells in the tumor stroma [35]. CAFs have multiple sources and are highly heterogeneous, and the roles of different types of CAFs in tumor progression are multifaceted [36,37]. ...
Background
Computed tomography (CT)-detected extramural venous invasion (EMVI) has been identified as independent risk factors for distant metastasis in patients with advanced gastric cancer (GC). Cancer-associated fibroblasts (CAFs) are crucial for remodeling the tumor microenvironment in GC. This study aimed to explore the relationship between CAFs and EMVI imaging characteristics to provide a new entry point for the diagnosis and treatment of GC.
Methods
We collected postoperative pathological specimens from 13 patients with advanced GC associated with EMVI. Next generation sequencing and radiogenomics correlation analysis was used to identify the relationship between the EMVI score and the degree of CAFs infiltration in GC. Based on single-cell sequencing data, we completed pathway activity and functional enrichment analyses for specific CAF subtypes in GC. CAFs were extracted using the collagenase method and were cocultured with GC cell line in vitro. After lentivirus-mediated regulation of MFAP5 and LDHA expression, we detected changes in the degree of EMT and the invasion ability in GC cell. A nude mouse orthotopic EMVI model was constructed, and MRI and Immunohistochemistry were performed to verify that MFAP5 affected EMVI in GC by regulating LDHA.
Results
The correlation analysis results showed that the EMVI score of GC patients was directly proportional to the degree of CAFs infiltration, and the degree of CAFs infiltration in GC was closely related to EMT pathway Single-cell data analysis suggested that the Fibro-MFAP5+ subtypes were enriched in tumor lactylation modification and EMT. Immunohistochemistry revealed that the expression of MFAP5, L-lactyl and EMT markers in GC tissues was proportional to the EMVI score. After knocking down MFAP5 in CAFs, the levels of L-lactyl and histone lactylation modifications were significantly reduced, and the sphere-forming ability and blood vessel formation ability of CAFs were significantly inhibited. Cell functional experiments demonstrated that MFAP5+ CAFs could affect EMT and the metastasis and invasion capabilities of GC cells. The results obtained with the nude mouse EMVI model suggested that MFAP5+ CAFs may promote the acquisition of EMVI features in GC by regulating lactylation modification.
Conclusions
This study explores the relationship between radiographic features of GC and the tumor microenvironment, and preliminarily elucidates its potential mechanisms. This innovative work may provide important new insights into the diagnosis and treatment of GC.
... Cancer-associated fibroblasts (CAFs), the most abundant cell type in the TME, are activated fibroblasts and are the center of cross-communication between various cellular components. CAFs consist of highly heterogeneous subpopulations with different or even opposite functions, and can be derived from inactive fibroblasts, adipocytes, endothelial cells, and stellate cells [120]. Yu et al. proposed that ineffective clinical CAF-directed interventions can be circumvented by selectively targeting specific CAF subgroups. ...
Due to the unique characteristics of breast cancer initiation sites and significant alterations in tumor metabolism, breast cancer cells rely on lipid metabolic reprogramming to effectively regulate metabolic programs during the disease progression cascade. This adaptation enables them to meet the energy demands required for proliferation, invasion, metastasis, and responses to signaling molecules in the breast cancer microenvironment. In this review, we comprehensively examined the distinctive features of lipid metabolic reprogramming in breast cancer and elucidated the underlying mechanisms driving aberrant behavior of tumor cells. Additionally, we emphasize the potential role and adaptive changes in lipid metabolism within the breast cancer microenvironment, while summarizing recent preclinical studies. Overall, precise control over lipid metabolism rewiring and understanding of plasticity within the breast cancer microenvironment hold promising implications for developing targeted treatment strategies against this disease. Therefore, interventions targeting the lipid metabolism in breast cancer may facilitate innovative advancements in clinical applications.
... Another mechanism of resistance is mediated by cancer associated fibroblasts (CAFs), which protect tumor cells through cell-to-cell contacts, secretion of stromal factors, and metabolic interactions [47]. We observed a reduction in the efficacy of nivolumab/cisplatin when primary MPM cells were cultured in the presence of fibroblasts. ...
Targeting aberrantly expressed kinases in malignant pleural mesothelioma (MPM) is a promising therapeutic strategy. We here investigated the effect of the novel and highly selective Phosphoinositide 3-kinase delta (PI3K-δ) inhibitor roginolisib (IOA-244) on MPM cells and on the immune cells in MPM microenvironment.
To this aim, we analyzed the expression of PI3K-δ by immunohistochemistry in specimens from primary MPM, cell viability and death in three different MPM cell lines treated with roginolisib alone and in combination with ipatasertib (AKT inhibitor) and sapanisertib (mTOR inhibitor). In a co-culture model of patient-derived MPM cells, autologous peripheral blood mononuclear cells and fibroblasts, the tumor cell viability and changes in immune cell composition were investigated after treatment of roginolisib with nivolumab and cisplatin. PI3K-δ was detected in 66/89 (74%) MPM tumors and was associated with reduced overall survival (12 vs. 25 months, P=0.0452). Roginolisib induced apoptosis in MPM cells and enhanced the anti-tumor efficacy of AKT and mTOR kinase inhibitors by suppressing PI3K-δ/AKT/mTOR and ERK1/2 signaling. Furthermore, the combination of roginolisib with chemotherapy and immunotherapy re-balanced the immune cell composition, increasing effector T-cells and reducing immune suppressive cells. Overall, roginolisib induces apoptosis in MPM cells and increases the antitumor immune cell effector function when combined with nivolumab and cisplatin.
These results provide first insights on the potential of roginolisib as a therapeutic agent in patients with MPM and its potential in combination with established immunotherapy regimen.
... BA can penetrate the mitochondrial membrane, disrupting its ability to function as a physical barrier and to support oxidative phosphorylation, as well as inducing the production of cytotoxic reactive oxygen species (ROS). 40 We confirmed that F/CL@BM induced ROS production in 4T1 tumor cells cultured alone or together with NIH 3T3 fibroblasts, and the production was greater than with either drug on its own ( Figure 5A and B). We further confirmed that this ROS production depolarized the mitochondrial membrane, and the effect was stronger with F/CL@BM than with either drug on its own ( Figure 5C). ...
Purpose
Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer. However, the effect of current treatment strategies by inducing tumor cell apoptosis alone is not satisfactory. The growth, metastasis and treatment sensitivity of tumors can be strongly influenced by cancer-associated fibroblasts (CAFs) in the microenvironment. Effective cancer therapies may need to target not only the tumor cells directly but also the CAFs that protect them.
Methods
Celastrol and small-sized micelles containing betulinic acid were co-encapsulated into liposomes using the thin-film hydration method (CL@BM). Folic acid was further introduced to modify liposomes as the targeting moiety (F/CL@BM). We established a novel NIH3T3+4T1 co-culture model to mimic the tumor microenvironment and assessed the nanocarrier’s inhibitory effects on CAFs-induced drug resistance and migration in the co-culture model. The in vivo biological distribution, fluorescence imaging, biological safety evaluation, and combined therapeutic effect evaluation of the nanocarrier were carried out based on a triple-negative breast cancer model.
Results
In the present study, a novel multifunctional nano-formulation was designed by combining the advantages of sequential release, co-loading of tretinoin and betulinic acid, and folic acid-mediated active targeting. As expected, the nano-formulation exhibited enhanced cytotoxicity in different cellular models and effectively increased drug accumulation at the tumor site by disrupting the cellular barrier composed of CAFs by tretinoin. Notably, the co-loaded nano-formulations proved to be more potent in inhibiting tumor growth in mice and also showed better anti-metastatic effects in lung metastasis models compared to the formulations with either drug alone. This novel drug delivery system has the potential to be used to develop more effective cancer therapies.
Conclusion
Targeting CAFs with celastrol sensitizes tumor cells to chemotherapy, increasing the efficacy of betulinic acid. The combination of drugs targeting tumor cells and CAFs may lead to more effective therapies against various cancers.
... The tumor microenvironment (TME), which consists primarily of the extracellular matrix (ECM), is crucial to various aspects of tumor progression, such as tumorigenesis, metastasis, relapse and treatment resistance, making it a potential target for cancer therapies (1,2). The TME is a complex system comprising a range of cellular and noncellular elements, and cancer-associated fibroblasts (CAFs), which are highly abundant in the tumor stroma and exhibit potent regulatory effects on tumor growth (3,4). The induction of cell senescence through traditional cancer treatments is one of the most notable mechanisms of tumor suppression. ...
Current cancer treatments target tumor cells; however, the tumor microenvironment (TME) induces therapeutic resistance, tumor development and metastasis, thus rendering these treatments ineffective. Research on the TME has therefore concentrated on nonmalignant cells. Cancer-associated fibroblasts (CAFs) are a major TME component, which contribute to cancer progression due to their diverse origins, phenotypes and functions, including cancer cell invasion and migration, extracellular matrix remodeling, tumor metabolism modulation and therapeutic resistance. Standard cancer treatment typically exacerbates the senescence-associated secretory phenotype (SASP) of senescent cancer cells and nonmalignant cells that actively leak proinflammatory signals in the TME. Therapy-induced senescence may impair cancer cell activity and compromise treatment responsiveness. CAFs and SASP are well-studied in the formation and progression of cancer. The present review discusses the current data on CAF senescence caused by anticancer treatment and assesses how senescence-like CAFs affect tumor formation. The development of senolytic medication for aging stromal cells is also highlighted. Combining cancer therapies with senolytics may boost therapeutic effects and provide novel possibilities for research.
... However, we did observe statistically significant distinctions in MDSC, Exclusion, CAF and TAMM2 between these subgroups. It is worthy to note that CAF-specific therapy has emerged as a valuable adjunct to immunotherapy, offering substantial clinical benefits for cancer patients (35). Some studies revealed the important regulatory role of the PI3K/Akt/ mTOR pathway in transformation of lung cancer growth patterns and chemotherapy resistance (36). ...
Objective
This paper aimed to investigate the PI3K/Akt/mTOR signal-pathway regulator factor-related lncRNA signatures (PAM-SRFLncSigs), associated with regulators of the indicated signaling pathway in patients with lung adenocarcinoma (LUAD) undergoing immunotherapy.
Materials and Methods
In this retrospective study, we employed univariate Cox, multivariate Cox, and least absolute shrinkage and selection operator (LASSO) regression analyses to identify prognostically relevant long non-coding RNAs (lncRNAs), construct prognostic models, and perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Subsequently, immunoassay and chemotherapy drug screening were conducted. Finally, the prognostic model was validated using the Imvigor210 cohort, and tumor stem cells were analyzed.
Results
We identified seven prognosis-related lncRNAs (AC084757.3, AC010999.2, LINC02802, AC026979.2, AC024896.1, LINC00941 and LINC01312). We also developed prognostic models to predict survival in patients with LUAD. KEGG enrichment analysis confirmed association of LUAD with the PI3K/Akt/mTOR signaling pathway. In the analysis of immune function pathways, we discovered three good prognostic pathways (Cytolytic_activity, Inflammation-promoting, T_cell_co-inhibition) in LUAD. Additionally, we screened 73 oncology chemotherapy drugs using the "pRRophetic" algorithm.
Conclusion
Identification of seven lncRNAs linked to regulators of the PI3K/Akt/mTOR signaling pathway provided valuable insights into predicting the prognosis of LUAD, understanding the immune microenvironment and optimizing immunotherapy strategies.
... In addition, current researches have proven that the TME plays a vital role in the procedure of tumor drug resistance [23] and have also proven the cross-link interference between metabolic reprogramming of cancer cells and the changes in the TME [24,25]. Saw PE et al. proposed targeting cancer-associated fibroblasts (CAFs) to overcome anticancer drug resistance [26]. Particularly, in our study, we discovered that endothelial cells and fibroblasts obviously infiltrated in the TME of the high RM-RS subgroup. ...
Bladder cancer (BLCA) is the most frequent malignant tumor of the genitourinary system. Postoperative chemotherapy drug perfusion and chemotherapy are important means for the treatment of BLCA. However, once drug resistance occurs, BLCA develops rapidly after recurrence. BLCA cells rely on unique metabolic rewriting to maintain their growth and proliferation. However, the relationship between the metabolic pattern changes and drug resistance in BLCA is unclear. At present, this problem lacks systematic research. In our research, we identified and analyzed resistance- and metabolism-related differentially expressed genes (RM-DEGs) based on RNA sequencing of a gemcitabine-resistant BLCA cell line and metabolic-related genes (MRGs). Then, we established a drug resistance- and metabolism-related model (RM-RM) through regression analysis to predict the overall survival of BLCA. We also confirmed that RM-RM had a significant correlation with tumor metabolism, gene mutations, tumor microenvironment, and adverse drug reactions. Patients with a high drug resistance- and metabolism-related risk score (RM-RS) showed more active lipid synthesis than those with a low RM-RS. Further in vitro and in vivo studies were implemented using Fatty Acid Synthase (FASN), a representative gene, which promotes gemcitabine resistance, and its inhibitor (TVB-3166) that can reverse this resistance effect.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12967-024-04867-8.
... CAFs exert substantial influence on tumour cells and TME, through ECM remodeling, metabolic alterations and secreting factors, which could impact the responses to ICI therapies. 64,65 Therefore, they are regarded as potential targets for cancer therapy. reduced the desmoplastic stromal structure and tumour vascular density, resulting in significant anti-tumour effects in human lung cancer xenografts and syngeneic murine pancreatic cancers. ...
Background
Cancer‐associated fibroblasts (CAFs) are potential targets for cancer therapy. Due to the heterogeneity of CAFs, the influence of CAF subpopulations on the progression of lung cancer is still unclear, which impedes the translational advances in targeting CAFs.
Methods
We performed single‐cell RNA sequencing (scRNA‐seq) on tumour, paired tumour‐adjacent, and normal samples from 16 non‐small cell lung cancer (NSCLC) patients. CAF subpopulations were analyzed after integration with published NSCLC scRNA‐seq data. SpaTial enhanced resolution omics‐sequencing (Stereo‐seq) was applied in tumour and tumour‐adjacent samples from seven NSCLC patients to map the architecture of major cell populations in tumour microenvironment (TME). Immunohistochemistry (IHC) and multiplexed IHC (mIHC) were used to validate marker gene expression and the association of CAFs with immune infiltration in TME.
Results
A subcluster of myofibroblastic CAFs, POSTN ⁺ CAFs, were significantly enriched in advanced tumours and presented gene expression signatures related to extracellular matrix remodeling, tumour invasion pathways and immune suppression. Stereo‐seq and mIHC demonstrated that POSTN ⁺ CAFs were in close localization with SPP1 ⁺ macrophages and were associated with the exhausted phenotype and lower infiltration of T cells. POSTN expression or the abundance of POSTN ⁺ CAFs were associated with poor prognosis of NSCLC.
Conclusions
Our study identified a myofibroblastic CAF subpopulation, POSTN ⁺ CAFs, which might associate with SPP1 ⁺ macrophages to promote the formation of desmoplastic architecture and participate in immune suppression. Furthermore, we showed that POSTN ⁺ CAFs associated with cancer progression and poor clinical outcomes and may provide new insights on the treatment of NSCLC.
... 17 Furthermore, CAFs, the most abundant stromal cells in the tumor microenvironment (TME), are involved in the resistance to cancer therapeutics. 18 To further investigate changes in T cells following MS023 treatment, we re-clustered the T-cell population and identified CD8, CD4, and natural killer (NK) cell subpopulations ( Figure 2D). Flow cytometry analysis confirmed that the proportion of CD8 T cells was significantly higher in the MS023-treated group ( Figure 2E,F). ...
Background
Immune‐checkpoint blockade (ICB) therapy shows promise for treating aggressive triple‐negative breast cancer (TNBC). However, only some patients benefit from ICB, revealing an urgent need for identifying novel strategies for sensitizing patients to ICB. Previously, the authors demonstrated that type‐I protein arginine methyltransferases (PRMTs) regulated antiviral innate‐immune responses in TNBC by altering RNA splicing. This study aimed to explore the effects of targeting type‐I PRMTs on the tumor microenvironment (TME) and the efficacy of ICB therapy against TNBC.
Methods
Single‐cell transcriptomic analysis was performed to investigate the effects of type‐I PRMT inhibition on the TME, especially T‐cell subsets. Single‐cell T‐cell receptor sequencing was performed to analyze the diversity and dynamics of the T‐cell repertoire. A syngeneic murine model of TNBC was used to evaluate the therapeutic efficacy and immune memory effect of combining a type‐I PRMT inhibitor (MS023) with an anti‐programmed cell death protein 1 (PD‐1) antibody.
Results
Type‐I PRMT inhibition combined with anti–PD‐1 therapy reduced tumor growth. Mechanistically, type‐I PRMT inhibition reshaped the TME. Increased CD8 T‐cell infiltration was verified using flow cytometry. Increased clonotypes and clonal diversity were also observed after MS023 treatment, which contributed to immune memory following combination treatment.
Conclusions
Targeting type‐I PRMT can potentially improve immunotherapeutic efficacies in patients with TNBC. By enhancing the tumor immunogenicity and promoting a more favorable immune microenvironment, this combined approach may enable more patients with TNBC to benefit from immunotherapies.
... However, while solid tumor therapy with TCE antibody constructs remains an attractive treatment approach, the selection of appropriate targets is crucial. Dense CAFs exhibit high expression of fibroblast activation protein (FAP) in the immunosuppressive TME of various solid tumors [34][35][36][37][38][39]. In addition, one of the major checkpoint pathways represents a tumor-induced immunosuppressive milieu mediated by the PD-1/PD-L1 axis of high PD-1 expression on activated T cells interacting with PD-L1 on tumor cells [40]. ...
Background
T cell engagers (TCEs) have been established as an emerging modality for hematologic malignancies, but solid tumors remain refractory. However, the upregulation of programmed cell death 1 (PD-1) is correlated with T cell dysfunction that confer tumor-mediated immunosuppression. Developing a novel nanobody-based trispecific T cell engager (Nb-TriTE) would be a potential strategy to improve therapeutic efficacy.
Methods
Given the therapeutic potential of nanobodies (Nbs), we first screened Nb targeting fibroblast activation protein (FAP) and successfully generated a Nb-based bispecific T cell engager (Nb-BiTE) targeting FAP. Then, we developed a Nb-TriTE by fusing an anti-PD-1 Nb to the Nb-BiTE. The biological activity and antitumor efficacy of the Nb-TriTE were evaluated in vitro and in both cell line-derived and patient-derived xenograft mouse models.
Results
We had for the first time successfully selected a FAP Nb for the generation of novel Nb-BiTE and Nb-TriTE, which showed good binding ability to their targets. Nb-TriTE not only induced robust tumor antigen-specific killing, potent T cell activation and enhanced T cell function in vitro, but also suppressed tumor growth, improved survival and mediated more T cell infiltration than Nb-BiTE in mouse models of different solid tumors without toxicity.
Conclusions
This novel Nb-TriTE provides a promising and universal platform to overcome tumor-mediated immunosuppression and improve patient outcomes in the future.
... Another reason for cancer resistance may be attributed to cancer-associated fibroblasts (CAFs) present in TME of many cancer types. CAFs can affect tumor cells' development, growth, aggressiveness, and metastatic behavior, so targeting CAFs can overcome drug resistance in cancer therapy [184]. As an essential component of the TME, CAFs contribute to cancer growth and progression by triggering extracellular matrix (ECM) deposition and remodeling, exchanging signals with cancer cells, and bidirectional cross talks with immune cells [185]. ...
Epithelial–mesenchymal transition (EMT) is a cell remodeling process in which epithelial cells undergo a reversible phenotype switch via the loss of adhesion capacity and acquisition of mesenchymal characteristics. In other words, EMT activation can increase invasiveness and metastatic properties, and prevent the sensitivity of tumor cells to chemotherapeutics, as mesenchymal cells have a higher resistance to chemotherapy and immunotherapy. EMT is orchestrated by a complex and multifactorial network, often linked to episodic, transient, or partial events. A variety of factors have been implicated in EMT development. Based on this concept, multiple metabolic pathways and master transcription factors, such as Snail, Twist, and ZEB, can drive the EMT. Emerging evidence suggests that oxidative stress plays a significant role in EMT induction. One emerging theory is that reducing mitochondrial-derived reactive oxygen species production may contribute to EMT development. This review describes how metabolic pathways and transcription factors are linked to EMT induction and addresses the involvement of signaling pathways.
... Increased levels of hypoxia and metabolic stress, along with increased tissue stiffness, may be associated with chemoresistance [80,81]. Besides the effect of cancer on the ECM structure and composition, CAFs as the largest population of stromal cells mediate the remodeling of the ECM and participate in the development of resistance to anticancer therapy [82,83]. While resistance to cisplatin is well established, the specific resistance to gemcitabine, oxaliplatin, and paclitaxel has been also found to correlate with CAF expression in various cancers [84]. ...
Simple Summary
The aberrant sialylation of membrane glycocalyx plays a pivotal role in the regulation of malignant cell behavior and correlates with a worse prognosis and shorter overall survival for patients. The biological and physical properties of sialome determine the negative charge and high hydrophilicity of cell membranes and thereby regulate cell–cell and cell–extracellular matrix interactions. There is increasing evidence that sialic acids influence cellular susceptibility in therapeutic management. Here, we focus on the engagement of sialic acids in chemoresistance and the potential effects of drugs and potential therapeutic agents on sialome-related machinery in malignant cells.
Abstract
A cellular sialome is a physiologically active and dynamically changing component of the cell membrane. Sialylation plays a crucial role in tumor progression, and alterations in cellular sialylation patterns have been described as modulators of chemotherapy effectiveness. However, the precise mechanisms through which altered sialylation contributes to drug resistance in cancer are not yet fully understood. This review focuses on the intricate interplay between sialylation and cancer treatment. It presents the role of sialic acids in modulating cell–cell interactions, the extracellular matrix (ECM), and the immunosuppressive processes within the context of cancer. The issue of drug resistance is also discussed, and the mechanisms that involve transporters, the tumor microenvironment, and metabolism are analyzed. The review explores drugs and therapeutic approaches that may induce modifications in sialylation processes with a primary focus on their impact on sialyltransferases or sialidases. Despite advancements in cellular glycobiology and glycoengineering, an interdisciplinary effort is required to decipher and comprehend the biological characteristics and consequences of altered sialylation. Additionally, understanding the modulatory role of sialoglycans in drug sensitivity is crucial to applying this knowledge in clinical practice for the benefit of cancer patients.
... Digging deep into the literature on the organ-type-specific origin, subtype(s), heterogeneity, activation, and functions of CAFs [13,14], it appears that the involvement of CAF in the development of treatment resistance is undeniable in a wide range of solid tumors [9,[15][16][17]. In recent years, CAF has been recognized as the non-redundant component of TME that individually interacts with tumor cells as well as the rest of TME, endothelial cells, and immune cells. ...
... Based on the results of this study, HK2 expression displayed a negative relationship to Tregs in ltration in DLBC and STAD (Fig. 10). Cancer associated broblasts (CAFs), one of the critical components of the TME, are capable of secreting a variety of cytokines to promote the tumour angiogenesis, induce the epithelial interstitial transformation of tumour cells, break the homeostasis between tissues and cells, and shape the TME more conducive to tumour progression [32,33] . This study suggested that the HK2 expression displayed a signi cant negative relationship to CAFs in STAD. ...
Background: Hexokinase 2 (HK2) takes on critical significance in glycolysis as the primary rate-limiting enzyme, which can carefully control the phosphorylation of glucose. The non-metabolic functions exhibited by HK2 have been extensively reported as immunometabolism research has been leaping forward. Nevertheless, the non-canonical functions exhibited by HK2 on cancer immunity have been rarely investigated.
Methods: HK2 expression was investigated in nine cancer types with the datasets originating from The Cancer Genome Atlas (TCGA). Subsequently, survival analysis (e.g., progression free interval (PFI), disease-specific survival (DSS) and overall survival (OS)) was performed in different tumor diseases. Moreover, we determined the relationship coefficient of clinicopathologic features and HK2 expression. Besides, the relationship coefficient of clinicopathologic features and HK2 expression was calculated. Lastly, the relationships of microsatellite instability (MSI), tumor mutation burden (TMB), prognosis, and HK2 expression were determined.
Results: HK2 demonstrated profound and pervasive overexpression across most tumour diseases.
Conclusions: This study revealed that HK2 may contribute to shaping the immunosuppressive tumor microenvironment (TME) and facilitate the progression of tumor in LGG and GBM by affecting the anti-tumor functions of immune cells.
While cancer-associated fibroblasts (CAFs) are crucial in influencing tumor growth and immune responses in lung cancer, we still lack a comprehensive understanding of their spatial organization associated with tumor progression and clinical outcomes. This gap highlights the need to elucidate how the intricate spatial arrangement of CAFs affects their interactions within the tumor microenvironment, ultimately shaping cancer progression and patient prognosis. Here, we unveil the spatial diversity of CAFs in lung squamous cell carcinoma (LUSC), a prevalent and aggressive lung cancer type, elucidating their impact on tumor progression and patient outcomes using spatial transcriptomics (ST). Image-based ST data from 33 LUSC patients demonstrated a significant association of spatial interactions of tumor epithelium and CAFs with tumor size and metabolic activity measured by [18F]fluorodeoxyglucose PET. Furthermore, the proximity of fibroblasts to tumor epithelial cells was linked to recurrence-free survival in LUSC patients. By characterizing CAFs based on their spatial relationship, we identified distinct molecular signatures related to spatially distinct fibroblast subpopulations. In addition, barcode-based ST data from 8 LUSC patients revealed spatially overlapping fibroblast regions characterized by upregulated glycolysis pathways. Our study underscores the importance of the complex spatial dynamics of the tumor microenvironment revealed by ST and its implications for patient outcomes in LUSC.
Transmembrane protein 92 (TMEM92) has been implicated in the facilitation of tumor progression. Nevertheless, comprehensive analyses concerning the prognostic significance of TMEM92, as well as its role in immunological responses across diverse cancer types, remain to be elucidated.
In this study, data was sourced from a range of publicly accessible online platforms and databases, including TCGA, GTEx, UCSC Xena, CCLE, cBioPortal, HPA, TIMER2.0, GEPIA, CancerSEA, GDSC, exoRBase, and ImmuCellAI. We systematically analyzed the expression patterns of TMEM92 at both mRNA and protein levels across diverse human organs, tissues, extracellular vesicles (EVs), and cell lines associated with multiple cancer types. Subsequently, analyses were conducted to determine the relationship between TMEM92 and various parameters such as prognosis, DNA methylation, copy number variation (CNV), the tumor microenvironment (TME), immune cell infiltration, genes with immunological relevance, tumor mutational burden (TMB), microsatellite instability (MSI), mismatch repair (MMR), and half-maximal inhibitory concentration (IC50) values.
In the present study, we observed a pronounced overexpression of TMEM92 across a majority of cancer types, which was concomitantly associated with a less favorable prognosis. A notable association emerged between TMEM92 expression and both DNA methylation and CNV. Furthermore, a pronounced relationship was discerned between TMEM92 expression, the TME, and the degree of immune cell infiltration. Intriguingly, while TMEM92 expression displayed a positive correlation with macrophage presence, it inversely correlated with the infiltration level of CD8 + T cells. Concurrently, significant associations were identified between TMEM92 and the major histocompatibility complex, TMB, MSI, and MMR. Results derived from Gene Set Enrichment Analysis and Gene Set Variation Analysis further substantiated the nexus of TMEM92 with both immune and metabolic pathways within the oncogenic context.
These findings expanded the understanding of the roles of TMEM92 in tumorigenesis and progression and suggest that TMEM92 may have an immunoregulatory role in several malignancies.
The journey of cancer development is a multifaceted and staged process. The array of treatments available for cancer varies significantly, dictated by the disease's type and stage. Cancer-associated fibroblasts (CAFs), prevalent across various cancer types and stages, play a pivotal role in tumor genesis, progression, metastasis, and drug resistance. The strategy of concurrently targeting cancer cells and CAFs holds great promise in cancer therapy. In this review, we focus intently on CAFs, delving into their critical role in cancer's progression. We begin by exploring the origins, classification, and surface markers of CAFs. Following this, we emphasize the key cytokines and signaling pathways involved in the interplay between cancer cells and CAFs and their influence on the tumor immune microenvironment. Additionally, we examine current therapeutic approaches targeting CAFs. This article underscores the multifarious roles of CAFs within the tumor microenvironment and their potential applications in cancer treatment, highlighting their importance as key targets in overcoming drug resistance and enhancing the efficacy of tumor therapies.
Lung squamous cell carcinoma (LUSC) is one of the subtypes of lung cancer (LC) that contributes to approximately 25%–30% of its prevalence. Cancer‐associated fibroblasts (CAFs) are key cellular components of the TME, and the large number of CAFs in tumour tissues creates a favourable environment for tumour development. However, the function of CAFs in the LUSC is complex and uncertain. First, we processed the scRNA‐seq data and classified distinct types of CAFs. We also identified prognostic CAFRGs using univariate Cox analysis and conducted survival analysis. Additionally, we assessed immune cell infiltration in CAF clusters using ssGSEA. We developed a model with a significant prognostic correlation and verified the prognostic model. Furthermore, we explored the immune landscape of LUSC and further investigated the correlation between malignant features and LUSC. We identified CAFs and classified them into three categories: iCAFs, mCAFs and apCAFs. The survival analysis showed a significant correlation between apCAFs and iCAFs and LUSC patient prognosis. Kaplan–Meier analysis showed that patients in CAF cluster C showed a better survival probability compared to clusters A and B. In addition, we identified nine significant prognostic CAFRGs (CLDN1, TMX4, ALPL, PTX3, BHLHE40, TNFRSF12A, VKORC1, CST3 and ADD3) and subsequently employed multivariate Cox analysis to develop a signature and validate the model. Lastly, the correlation between CAFRG and malignant features indicates the potential role of CAFRG in promoting tumour angiogenesis, EMT and cell cycle alterations. We constructed a CAF prognostic signature for identifying potential prognostic CAFRGs and predicting the prognosis and immunotherapeutic response for LUSC. Our study may provide a more accurate prognostic assessment and immunotherapy targeting strategies for LUSC.
Tumor-associated tertiary lymphoid structures (TLS) have been associated with favorable clinical outcomes and response to immune checkpoint inhibitors in many cancer types, including non-small cell lung cancer. Although the detailed cellular and molecular mechanisms underlying these clinical associations have not been fully elucidated, growing preclinical and clinical studies are helping to elucidate the mechanisms at the basis of TLS formation, composition, and regulation of immune responses. However, a major challenge remains how to exploit TLS to enhance naïve and treatment-mediated antitumor immune responses. Here, we discuss the current understanding of tumor-associated TLS, preclinical models that can be used to study them, and potential therapeutic interventions to boost TLS formation, with a particular focus on lung cancer research.
At present, tumor metastasis still remains the leading contributor to high recurrence and mortality in cancer patients. There have been no clinically effective therapeutic strategies for treating patients with metastatic cancer. In recent years, a growing body of evidence has shown that the pre-metastatic niche (PMN) plays a crucial role in driving tumor metastasis. Nevertheless, a clear and detailed understanding of the formation of PMN is still lacking given the fact that PMN formation involves in a wealth of complicated communications and underlying mechanisms between primary tumors and metastatic target organs. Despite that the roles of numerous components including tumor exosomes and extracellular vesicles in influencing the evolution of PMN have been well documented, the involvement of cancer-associated fibroblasts (CAFs) in the tumor microenvironment for controlling PMN formation is frequently overlooked. It has been increasingly recognized that fibroblasts trigger the formation of PMN by virtue of modulating exosomes, metabolism and so on. In this review, we mainly summarize the underlying mechanisms of fibroblasts from diverse origins in exerting impacts on PMN evolution, and further highlight the prospective strategies for targeting fibroblasts to prevent PMN formation.
A major challenge for inhibiting metastasis is the ability of cancer cells to reversibly switch states in response to microenvironmental cues along the metastatic cascade. The regulatory factors and signals from the microenvironment enabling colorectal cancer (CRC) cells to transition into an invasive state and to establish metastasis in the liver remain unknown. Using a combination of single-cell multiomics and spatial transcriptomics data from primary and metastatic CRC patients, we reveal putative metastasis-initiating cancer states with regenerative and inflammatory signatures, driven by transcription factors AP-1, NF-κB and YAP. We demonstrate the existence of an intermediate population with a hybrid regenerative and stem phenotype, indicating phenotypic transitions between stem and pro-metastatic cells. Our spatial analyses show localisation of the regenerative states at the invasive edge in primary CRC and in an immunosuppressive niche in liver metastasis, surrounded by immune and stromal cells that sustain these cells. We uncover putative ligand-receptor interactions driven by cancer-associated fibroblasts (CAFs), macrophages and CD8 T cells that activate the regenerative and inflammatory invasive phenotype in cancer cells. Together, our findings reveal regulatory and signalling factors that can be targeted to restrict transition into invasive states to impair metastasis.
The tumor microenvironment (TME) plays an important role in various stages of tumor generation, metastasis, and evasion of immune monitoring and treatment. TME targeted therapy is based on TME components, related pathways or active molecules as therapeutic targets. Therefore, TME targeted therapy based on environmental differences between TME and normal cells has been widely studied. Biomimetic nanocarriers with low clearance, low immunogenicity, and high targeting have enormous potential in tumor treatment. This review introduces the composition and characteristics of TME, including cancer‑associated fibroblasts (CAFs), extracellular matrix (ECM), tumor blood vessels, non-tumor cells, and the latest research progress of biomimetic nanoparticles (NPs) based on TME. It also discusses the opportunities and challenges of clinical transformation of biomimetic nanoparticles.
Background:
Cancer-associated fibroblasts (CAFs) are a crucial component of the tumor microenvironment (TME) and play significant roles in tumor initiation, progression, and immune evasion. Despite this, the specific exosomal proteins derived from CAFs and their functions in esophageal squamous cell carcinoma (ESCC) remain unknown. Therefore, this study aims to investigate the impact and prognostic significance of CAFs-derived exosomal proteins in ESCC.
Materials and methods:
Exosomes obtained from CAFs and normal fibroblasts (NFs) were isolated using ultracentrifugation, and the protein expression profiles of the exosomes were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Tumor proliferation was assessed using CCK-8 and colony formation assays, while cell invasion and migration were evaluated using transwell assays. Lasso regression analysis was employed to establish a signature based on CAFs-derived exosomal proteins using the TCGA database. The immunological and prognostic roles of this signature were comprehensively investigated through survival analysis, gene set enrichment analysis (GSEA), immune analysis, immunotherapy response analysis, and drug sensitivity analysis. The GSE160269 dataset was utilized for single-cell transcriptome analysis to further elucidate the role of the signature in the TME. Additionally, cDNA microarray analysis was utilized to validate the prognostic value of the signature.
Results:
Our findings demonstrate that exosomes derived from CAFs significantly enhance the proliferation, invasion, and migration of esophageal cancer cells. We identified 842 differentially expressed exosomal proteins through LC-MS/MS analysis, and two key proteins were utilized to establish a risk signature. Survival analysis revealed a significantly worse prognosis in the high-risk group, with multivariate analysis indicating that the risk score serves as an independent prognostic factor. Moreover, we observed a significant correlation between the risk score and immune cell infiltration, immunotherapy response, and sensitivity to chemotherapeutic treatments in the study population. Lastly, single-cell transcriptome analysis further revealed the expression patterns of TNFRSF10B and ILF3 in different cell subpopulations.
Conclusion:
In conclusion, our study has successfully established a robust prognostic signature based on CAFs-derived exosomal proteins, which can serve as a reliable biomarker for predicting prognosis and evaluating the immune microenvironment in ESCC.
Cancer-associated fibroblasts (CAFs), a stromal cell population with cell-of-origin, phenotypic and functional heterogeneity, are the most essential components of the tumor microenvironment (TME). Through multiple pathways, activated CAFs can promote tumor growth, angiogenesis, invasion and metastasis, along with extracellular matrix (ECM) remodeling and even chemoresistance. Numerous previous studies have confirmed the critical role of the interaction between CAFs and tumor cells in tumorigenesis and development. However, recently, the mutual effects of CAFs and the tumor immune microenvironment (TIME) have been identified as another key factor in promoting tumor progression. The TIME mainly consists of distinct immune cell populations in tumor islets and is highly associated with the antitumor immunological state in the TME. CAFs interact with tumor-infiltrating immune cells as well as other immune components within the TIME via the secretion of various cytokines, growth factors, chemokines, exosomes and other effector molecules, consequently shaping an immunosuppressive TME that enables cancer cells to evade surveillance of the immune system. In-depth studies of CAFs and immune microenvironment interactions, particularly the complicated mechanisms connecting CAFs with immune cells, might provide novel strategies for subsequent targeted immunotherapies. Herein, we shed light on recent advances regarding the direct and indirect crosstalk between CAFs and infiltrating immune cells and further summarize the possible immunoinhibitory mechanisms induced by CAFs in the TME. In addition, we present current related CAF-targeting immunotherapies and briefly describe some future perspectives on CAF research in the end.
Cancer-associated fibroblast (CAF) heterogeneity is increasingly appreciated, but the origins and functions of distinct CAF subtypes remain poorly understood. The abundant and transcriptionally diverse CAF population in pancreatic ductal adenocarcinoma (PDAC) is thought to arise from a common cell of origin, pancreatic stellate cells (PSC), with diversification resulting from cytokine and growth factor gradients within the tumor microenvironment. Here we analyzed the differentiation and function of PSCs during tumor progression in vivo. Contrary to expectations, we found that PSCs give rise to a numerically minor subset of PDAC CAFs. Targeted ablation of PSC-derived CAFs within their host tissue revealed nonredundant functions for this defined CAF population in shaping the PDAC microenvironment, including production of specific extracellular matrix components and tissue stiffness regulation. Together, these findings link stromal evolution from distinct cells of origin to transcriptional heterogeneity among PDAC CAFs and demonstrate unique functions for CAFs of a defined cellular origin.
Significance
By tracking and ablating a specific CAF population, we find that a numerically minor CAF subtype from a defined cell of origin plays unique roles in establishing the pancreatic tumor microenvironment. Together with prior studies, this work suggests that mesenchymal lineage heterogeneity and signaling gradients diversify PDAC CAFs.
See related commentary by Cukierman, p. 296.
This article is highlighted in the In This Issue feature, p. 275
The current pathological and molecular classification of pancreatic ductal adenocarcinoma (PDAC) provides limited guidance for treatment options, especially for immunotherapy. Cancer-associated fibroblasts (CAFs) are major players of desmoplastic stroma in PDAC, modulating tumor progression and therapeutic response. Using single-cell RNA sequencing, we explored the intertumoral heterogeneity among PDAC patients with different degrees of desmoplasia. We found substantial intertumoral heterogeneity in CAFs, ductal cancer cells, and immune cells between the extremely dense and loose types of PDACs (dense-type, high desmoplasia; loose-type, low desmoplasia). Notably, no difference in CAF abundance was detected, but a novel subtype of CAFs with a highly activated metabolic state (meCAFs) was found in loose-type PDAC compared to dense-type PDAC. MeCAFs had highly active glycolysis, whereas the corresponding cancer cells used oxidative phosphorylation as a major metabolic mode rather than glycolysis. We found that the proportion and activity of immune cells were much higher in loose-type PDAC than in dense-type PDAC. Then, the clinical significance of the CAF subtypes was further validated in our PDAC cohort and a public database. PDAC patients with abundant meCAFs had a higher risk of metastasis and a poor prognosis but showed a dramatically better response to immunotherapy (64.71% objective response rate, one complete response). We characterized the intertumoral heterogeneity of cellular components, immune activity, and metabolic status between dense- and loose-type PDACs and identified meCAFs as a novel CAF subtype critical for PDAC progression and the susceptibility to immunotherapy.
Cancer-associated fibroblasts (CAFs) exert a key role in cancer progression and liver metastasis. They are activated in the tumor microenvironment (TME), but their prometastatic mechanisms are not defined. CAFs are abundant in colorectal cancer (CRC). However, it is not clear whether they are raised from local tissue-resident fibroblasts or pericryptal fibroblasts and distant fibroblast precursors, and whether they may stimulate metastasis-promoting communication. B-cell lymphoma 9/B-cell lymphoma 9-like (BCL9/BCL9L) is the key transcription cofactor of β-catenin. We studied the TME of CRC with single-cell sequencing and consequently found that Bcl9 depletion caused a pro-tumor effect of CAFs, while inhibition of abnormal activation of Wnt/β-catenin signal through Bcl9 depletion benefited T-cell–mediated antitumor immune responses. We also identified and evaluated four types of CAFs in CRC with liver metastasis. In summary, we demonstrate cell type landscape and transcription difference upon BCL9 suppression in CAFs, as well as how CAF affects cancer associated immune surveillance by inhibition of Wnt signaling. Targeting the Wnt signaling pathway via modulating CAF may be a potential therapeutic approach.
Simple Summary
As our knowledge of cancer as a complex organ comprising tumor cells as well as surrounding cells within the microenvironment continues to grow, it is imperative to consider how the microenvironment may be supporting the cancer and promoting tumor progression. One aspect of the microenvironment that has gained significant interest over the past decade are cancer-associated fibroblasts, which have been implicated in diverse oncogenic roles including cancer invasion and metastasis, resistance to existing cancer therapeutics, angiogenesis, and tumor proliferation. The identification of cancer-associated fibroblasts and the pathways through which they promote tumor progression will allow us to target a specific subset of cells within the cancer niche in order to augment existing cancer therapies and possibly develop novel methods. In this review, we discuss the different markers that have been used to identify cancer-associated fibroblasts in various cancer contexts as potential therapeutic targets and discuss the role that cancer-associated fibroblasts play in enhancing cancer malignancy.
Abstract
In the era of genomic medicine, cancer treatment has become more personalized as novel therapeutic targets and pathways are identified. Research over the past decade has shown the increasing importance of how the tumor microenvironment (TME) and the extracellular matrix (ECM), which is a major structural component of the TME, regulate oncogenic functions including tumor progression, metastasis, angiogenesis, therapy resistance, and immune cell modulation, amongst others. Within the TME, cancer-associated fibroblasts (CAFs) have been identified in several systemic cancers as critical regulators of the malignant cancer phenotype. This review of the literature comprehensively profiles the roles of CAFs implicated in gastrointestinal, endocrine, head and neck, skin, genitourinary, lung, and breast cancers. The ubiquitous presence of CAFs highlights their significance as modulators of cancer progression and has led to the subsequent characterization of potential therapeutic targets, which may help advance the cancer treatment paradigm to determine the next generation of cancer therapy. The aim of this review is to provide a detailed overview of the key roles that CAFs play in the scope of systemic disease, the mechanisms by which they enhance protumoral effects, and the primary CAF-related markers that may offer potential targets for novel therapeutics.
Cancer-associated fibroblasts (CAFs) has been recognized as one cause of tumor resistance to immune checkpoint blockade therapy, but the underlying mechanisms still remain elusive. In the present study, a bone marrow-derived CAF (BMF) -rich tumor model is successfully established by subcutaneously mixed inoculation of BMFs and tumor cells into mice and the BMF-mixed tumor xenografts are demonstrated to be resistant to anti-PD-L1 antibody immunotherapy compared to the mere tumor xenografts. In vitro assays via the co-culture system of BMFs and tumor cells indicate that the co-cultured BMFs are induced to overexpress PD-L1, while there is no such a phenomenon in the co-cultured cancer cells. The further knock-out of PD-L1 in BMFs rescues the sensitivity of BMF-mixed tumor xenografts to PD-L1 blockade therapy. Mechanistically, via the microarray assay, we identify that the upregulation of PD-L1 in BMFs stimulated by cancer cells is medicated by the activation of the Wnt/β-catenin signaling pathway in BMFs. Moreover, the administration of Wnt/β-catenin signaling inhibitors, including XAV-939 and Wnt-C59, distinctly inhibits the upregulation of PD-L1 expression in the co-cultured BMFs. The further combination administration of XAV-939 significantly potentiates the therapeutic outcome of PD-L1 blockade therapy in BMF-mixed tumors. In summary, our study demonstrates that Wnt inhibition augments PD-L1 blockade efficacy by overcoming BMF-mediated immunotherapy resistance.
Background:
Irradiation has emerged as a valid tool for nasopharyngeal carcinoma (NPC) in situ treatment; however, NPC derived from tissues treated with irradiation is a main cause cancer-related death. The purpose of this study is to uncover the underlying mechanism regarding tumor growth after irradiation and provided potential therapeutic strategy.
Methods:
Fibroblasts were extracted from fresh NPC tissue and normal nasopharyngeal mucosa. Immunohistochemistry was conducted to measure the expression of α-SMA and FAP. Cytokines were detected by protein array chip and identified by real-time PCR. CCK-8 assay was used to detect cell proliferation. Radiation-resistant (IRR) 5-8F cell line was established and colony assay was performed to evaluate tumor cell growth after irradiation. Signaling pathways were acquired via gene set enrichment analysis (GSEA). Comet assay and γ-H2AX foci assay were used to measure DNA damage level. Protein expression was detected by western blot assay. In vivo experiment was performed subcutaneously.
Results:
We found that radiation-resistant NPC tissues were constantly infiltrated with a greater number of cancer-associated fibroblasts (CAFs) compared to radiosensitive NPC tissues. Further research revealed that CAFs induced the formation of radioresistance and promoted NPC cell survival following irradiation via the IL-8/NF-κB pathway to reduce irradiation-induced DNA damage. Treatment with Tranilast, a CAF inhibitor, restricted the survival of CAF-induced NPC cells and attenuated the of radioresistance properties.
Conclusions:
Together, these data demonstrate that CAFs can promote the survival of irradiated NPC cells via the NF-κB pathway and induce radioresistance that can be interrupted by Tranilast, suggesting the potential value of Tranilast in sensitizing NPC cells to irradiation.
Tumors consist of cancer cells and a network of non-cancerous stroma. Cancer-associated fibroblasts (CAF) are known to support tumorigenesis, and are emerging as immune modulators. Neutrophils release histone-bound nuclear DNA and cytotoxic granules as extracellular traps (NET). Here we show that CAFs induce NET formation within the tumor and systemically in the blood and bone marrow. These tumor-induced NETs (t-NETs) are driven by a ROS-mediated pathway dependent on CAF-derived Amyloid β, a peptide implicated in both neurodegenerative and inflammatory disorders. Inhibition of NETosis in murine tumors skews neutrophils to an anti-tumor phenotype, preventing tumor growth; reciprocally, t-NETs enhance CAF activation. Mirroring observations in mice, CAFs are detected juxtaposed to NETs in human melanoma and pancreatic adenocarcinoma, and show elevated amyloid and β-Secretase expression which correlates with poor prognosis. In summary, we report that CAFs drive NETosis to support cancer progression, identifying Amyloid β as the protagonist and potential therapeutic target.
Ferroptosis, a new mode of nonapoptotic cell death, is increasingly recognized as a new hope in overcoming resistance to chemotherapy in cancer. Both canonical and noncanonical pathways can trigger ferroptosis execution via an iron-dependent lethal lipid peroxidation manner. However, growing evidence has shown that some cancer cells can survive ferroptotic stress through metabolic remodeling as regards iron metabolism, anti-oxidative systems, and lipid metabolism. In addition to the well-known roles of the XC ⁻ /glutathione/glutathione peroxidase 4 (XC – /GSH/GPX4) axis in blocking ferroptosis, several recently identified pathways, including the Mevalonate-ferroptosis suppressor protein 1 (MVA-FSP1) axis, the GTP cyclohydrolase 1-Tetrahydrobiopterin (GCH1-BH 4 ) axis, the peroxisome-ether-phospholipid axis, the acyl-CoA synthetase long-chain family member 3-monounsaturated fatty acids (ACSL3-MUFA) axis, and the Liver kinase B1-AMP-activated protein kinase (LKB1-AMPK) axis, can negatively regulate susceptibility to ferroptosis. Prominin-2, a newly identified ferroptosis-modulating protein, also drives cancer cells to escape from ferroptosis induction. These findings collectively led to major challenges and opportunities in the development of novel therapies that target the ferroptosis resistance of cancer cells.
Significance
Ferroptosis is a lethal consequence of accumulated lipid peroxidation catalyzed by ferrous iron and oxygen. This unique cell death process appears to involve many diseases, such as neurodegeneration, ischemia/reperfusion injury, kidney disease, and a druggable target in therapy-resistant cancers. There is great expectation of being able to exploit ferroptosis for the treatment of as yet incurable diseases. However, the state of ferroptosis susceptibility is linked to various regulation pathways. This perspective aims to integrate the current understanding of signaling mechanisms for ferroptotic defenses and facilitates movement toward novel cancer therapeutic strategies.
Background & aims: Pancreatic ductal adenocarcinomas (PDAC) are characterized by fibrosis and an abundance of cancer-associated fibroblasts (CAFs). We investigated strategies to disrupt interactions among CAFs, the immune system, and cancer cells, focusing on adhesion molecule cadherin 11 (CDH11), which has been associated with other fibrotic disorders and is expressed by activated fibroblasts.
Methods: We compared levels of CDH11 mRNA in human pancreatitis and pancreatic cancer tissues and cells, compared with normal pancreas, and measured levels of CDH11 protein in human and mouse pancreatic lesions and normal tissues. We crossed p48-Cre;LSL-KrasG12D/+;LSL-Trp53R172H/+ (KPC) mice with CDH11-knockout mice and measured survival times of offspring. Pancreata were collected and analyzed by histology, immunohistochemistry, and (single-cell) RNA sequencing; RNA and proteins were identified by imaging mass cytometry. Some mice were given injections of PD1 antibody or gemcitabine and survival was monitored. Pancreatic cancer cells from KPC mice were subcutaneously injected into Cdh11+/+ and Cdh11-/- mice and tumor growth was monitored. Pancreatic cancer cells (mT3) from KPC mice (C57BL/6), were subcutaneously injected into Cdh11+/+ (C57BL/6J) mice and mice were given injections of antibody against CDH11, gemcitabine, or small molecule inhibitor of CDH11 (SD133) and tumor growth was monitored.
Results: Levels of CDH11 mRNA and protein were significantly higher in CAFs than in pancreatic cancer epithelial cells, human or mouse pancreatic cancer cell lines, or immune cells. KPC/Cdh11+/- and KPC/Cdh11-/- mice survived significantly longer than KPC/Cdh11+/+ mice. Markers of stromal activation entirely surrounded pancreatic intraepithelial neoplasias in KPC/Cdh11+/+ mice and incompletely in KPC/Cdh11+/- and KPC/Cdh11-/- mice, whose lesions also contained fewer FOXP3+ cells in the tumor center. Compared with pancreatic tumors in KPC/Cdh11+/+ mice, tumors of KPC/Cdh11+/- mice had increased markers of antigen processing and presentation; more lymphocytes and associated cytokines; decreased extracellular matrix components; and reductions in markers and cytokines associated with immunosuppression. Administration of the PD1 antibody did not prolong survival of KPC mice with 0, 1, or 2 alleles of Cdh11. Gemcitabine extended survival only of KPC/Cdh11+/- and KPC/Cdh11-/- mice or reduced subcutaneous tumor growth in mT3 engrafted Cdh11+/+ mice given in combination with the CDH11 antibody. A small molecule inhibitor of CDH11 reduced growth of pre-established mT3 subcutaneous tumors only if T and B cells were present in mice.
Conclusions: Knockout or inhibition of CDH11, which is expressed by CAFs in the pancreatic tumor stroma, reduces growth of pancreatic tumors, increases their response to gemcitabine, and significantly extends survival of mice. CDH11 promotes immunosuppression and extracellular matrix deposition, and might be developed as a therapeutic target for pancreatic cancer.
Keywords: activated stroma; anti-tumor immunity; desmoplasia; immunomodulation; inflammation
Despite the increasing interest in targeting stromal elements of the tumor microenvironment, we still face tremendous challenges in developing adequate therapeutics to modify the tumor stromal landscape. A major obstacle to this is our poor understanding of the phenotypic and functional heterogeneity of stromal cells in tumors. Herein, we perform an unbiased interrogation of tumor mesenchymal cells, delineating the co-existence of distinct subsets of cancer-associated fibroblasts (CAFs) in the microenvironment of murine carcinomas, each endowed with unique phenotypic features and functions. Furthermore, our study shows that neutralization of TGFβ in vivo leads to remodeling of CAF dynamics, greatly reducing the frequency and activity of the myofibroblast subset, while promoting the formation of a fibroblast population characterized by strong response to interferon and heightened immunomodulatory properties. These changes correlate with the development of productive anti-tumor immunity and greater efficacy of PD1 immunotherapy. Along with providing the scientific rationale for the evaluation of TGFβ and PD1 co-blockade in the clinical setting, this study also supports the concept of plasticity of the stromal cell landscape in tumors, laying the foundation for future investigations aimed at defining pathways and molecules to program CAF composition for cancer therapy.
Simple Summary
The extracellular matrix (ECM) has emerged as a critical part of the tumor microenvironment. This glycoprotein- and proteoglycan-rich part of the tumor serves as a niche for the enrichment of cancer stem cells that can drive resistance to therapy and metastasis. Additionally, the ECM can act as a barrier to drug delivery, thereby physically contributing to resistance to therapy. This review summarizes the role of the ECM in enriching for cancer stem cells and how it contributes to therapy resistance in cancer. Finally, it discusses the attempts to develop molecules that can target the ECM as potential therapy options.
Abstract
The extracellular matrix (ECM) has remained an enigmatic component of the tumor microenvironment. It drives metastasis via its interaction with the integrin signaling pathway, contributes to tumor progression and confers therapy resistance by providing a physical barrier around the tumor. The complexity of the ECM lies in its heterogeneous composition and complex glycosylation that can provide a support matrix as well as trigger oncogenic signaling pathways by interacting with the tumor cells. In this review, we attempt to dissect the role of the ECM in enriching for the treatment refractory cancer stem cell population and how it may be involved in regulating their metabolic needs. Additionally, we discuss how the ECM is instrumental in remodeling the tumor immune microenvironment and the potential ways to target this component in order to develop a viable therapy.
Cancer-associated fibroblasts (CAFs) are an essential component in the tumor microenvironment and have been reported to contribute to tumor progression through many mechanisms; however, the detailed mechanism underlying the immune-suppression effect of CAFs is not clearly defined. In this study, human breast cancer-derived CAFs were cultured, and CAF-derived exosomes in a culture medium were isolated. Using a miRNA profiles assay, we identify a significantly higher level of microRNA-92 isolated in CAFs exosomes. After treatment by CAF-derived exosomes, breast cancer cells express higher programmed cell death receptor ligand 1 (PD-L1), accompanied with increased miR-92 expression. Increased PD-L1 expression, which was induced by CAF-derived exosomes, significantly promotes apoptosis and impaired proliferation of T cells. The underlying mechanism of this effect was studied, proliferation and migration of breast cancer cells were increased after the transfection of miR-92, LATS2 was recognized as a target gene of miR-92, and further confirmed by a luciferase assay. Immunoprecipitation showed that LATS2 can interact with YAP1, chromatin immunoprecipitation confirmed that after nuclear translocation YAP1 could bind to the enhancer region of PD-L1 to promotes transcription activity. Furthermore, the animal study confirmed that CAFs significantly promoted tumor progression and impaired the function of tumor-infiltrated immune cells in vivo. Our data revealed a novel mechanism that can induce immune suppression in the tumor microenvironment.
Cancer-associated fibroblasts (CAFs) are indispensable architects of the tumor microenvironment. They perform the essential functions of extracellular matrix deposition, stromal remodeling, tumor vasculature modulation, modification of tumor metabolism, and participation in crosstalk between cancer and immune cells. In this review, we discuss our current understanding of the principal differences between normal fibroblasts and CAFs, the origin of CAFs, their functions, and ultimately, highlight the intimate connection of CAFs to virtually all of the hallmarks of cancer. We address the remarkable degree of functional diversity and phenotypic plasticity displayed by CAFs and strive to stratify CAF biology among different tumor types into practical functional groups. Finally, we summarize the status of recent and ongoing trials of CAF-directed therapies and contend that the paucity of trials resulting in Food and Drug Administration (FDA) approvals thus far is a consequence of the failure to identify targets exclusive of pro-tumorigenic CAF phenotypes that are mechanistically linked to specific CAF functions. We believe that the development of a unified CAF nomenclature, the standardization of functional assays to assess the loss-of-function of CAF properties, and the establishment of rigorous definitions of CAF subpopulations and their mechanistic functions in cancer progression will be crucial to fully realize the promise of CAF-targeted therapies.
Cancer associated fibroblasts (CAF) and the extracellular matrix (ECM) produced by them have been recognized as key players in cancer biology and emerged as important targets for cancer treatment and drug discovery. Apart from their presence in stroma rich tumors, such as biliary, pancreatic and subtypes of hepatocellular cancer (HCC), both CAF and certain ECM components are also present in cancers without an overt intra-tumoral desmoplastic reaction. They support cancer development, growth, metastasis and resistance to chemo- or checkpoint inhibitor therapy by a multitude of mechanisms, including angiogenesis, ECM remodeling and active immunosuppression by secretion of tumor promoting and immune suppressive cytokines, chemokines and growth factors. CAF resemble activated hepatic stellate cells (HSC)/myofibroblasts, expressing α-smooth muscle actin and especially fibroblast activation protein (FAP). Apart from FAP, CAF also upregulate other functional cell surface proteins like platelet-derived growth factor receptor β (PDGFRβ) or the insulin-like growth factor receptor II (IGFRII). Notably, if formulated with adequate size and zeta potential, injected nanoparticles home preferentially to the liver. Several nanoparticular formulations were tested successfully to deliver dugs to activated HSC/myofibroblasts. Thus, surface modified nanocarriers with a cyclic peptide binding to the PDGFRβ or with mannose-6-phosphate binding to the IGFRII, effectively directed drug delivery to activated HSC/CAF in vivo. Even unguided nanohydrogel particles and lipoplexes loaded with siRNA demonstrated a high in vivo uptake and functional siRNA delivery in activated HSC, indicating that liver CAF/HSC are also addressed specifically by well-devised nanocarriers with optimized physicochemical properties. Therefore, CAF have become an attractive target for the development of stroma-based cancer therapies, especially in the liver.
Pancreatic ductal adenocarcinoma (PDAC) remains a lethal cancer. The poor prognosis calls for a more detailed understanding of disease biology in order to pave the way for the development of effective therapies. Typically, the pancreatic tumor is composed of a minority of malignant cells within an excessive tumor microenvironment (TME) consisting of extracellular matrix (ECM), fibroblasts, immune cells, and endothelial cells. Research conducted in recent years has particularly focused on cancer-associated fibroblasts (CAFs) which represent the most prominent cellular component of the desmoplastic stroma. Here, we review the complex crosstalk between CAFs, tumor cells, and other components of the TME, and illustrate how these interactions drive disease progression. We also discuss the emerging field of CAF heterogeneity, their tumor-supportive versus tumor-suppressive capacity, and the consequences for designing stroma-targeted therapies in the future.
Neutrophil extracellular traps (NETs), which consist of chromatin DNA filaments coated with granule proteins, are released by neutrophils to trap microorganisms1,2,3. Recent studies have suggested that the DNA component of NETs (NET-DNA) is associated with cancer metastasis in mouse models4,5,6. However, the functional role and clinical importance of NET-DNA in metastasis in patients with cancer remain unclear. Here we show that NETs are abundant in the liver metastases of patients with breast and colon cancers, and that serum NETs can predict the occurrence of liver metastases in patients with early-stage breast cancer. NET-DNA acts as a chemotactic factor to attract cancer cells, rather than merely acting as a ‘trap’ for them; in several mouse models, NETs in the liver or lungs were found to attract cancer cells to form distant metastases. We identify the transmembrane protein CCDC25 as a NET-DNA receptor on cancer cells that senses extracellular DNA and subsequently activates the ILK–β-parvin pathway to enhance cell motility. NET-mediated metastasis is abrogated in CCDC25-knockout cells. Clinically, we show that the expression of CCDC25 on primary cancer cells is closely associated with a poor prognosis for patients. Overall, we describe a transmembrane DNA receptor that mediates NET-dependent metastasis, and suggest that targeting CCDC25 could be an appealing therapeutic strategy for the prevention of cancer metastasis.
Tumor mass consists of a complex ensemble of malignant cancer cells and a wide variety of resident and infiltrating cells, secreted factors, and extracellular matrix proteins that are referred as tumor microenvironment (TME). Cancer associated fibroblasts (CAFs) are key TME components that support tumor growth, generating a physical barrier against drugs and immune infiltration, and contributing to regulate malignant progression. Thus, it is largely accepted that therapeutic approaches aimed at hampering the interactions between tumor cells and CAFs can enhance the effectiveness of anti-cancer treatments. In this view, nucleic acid therapeutics have emerged as promising molecules. Here, we summarize recent knowledge about their role in the regulation of CAF transformation and tumor-promoting functions, highlighting their therapeutic utility and challenges.
A subset of cancer-associated fibroblasts (FAP+/CAF-S1) mediates immunosuppression in breast cancers, but its heterogeneity and its impact on immunotherapy response remain unknown. Here, we identify 8 CAF-S1 clusters by analyzing more than 19,000 single CAF-S1 fibroblasts from breast cancer. We validate the five most abundant clusters by flow cytometry and in silico analyses in other cancer types, highlighting their relevance. Myofibroblasts from clusters 0 and 3, characterized by extracellular matrix proteins and TGFβ signaling, respectively, are indicative of primary resistance to immunotherapies. Cluster 0/ecm-myCAF upregulates PD-1 and CTLA4 protein levels in regulatory T lymphocytes (Tregs), which, in turn, increases CAF-S1 cluster 3/TGFβ-myCAF cellular content. Thus, our study highlights a positive feedback loop between specific CAF-S1 clusters and Tregs and uncovers their role in immunotherapy resistance.
Significance
Our work provides a significant advance in characterizing and understanding FAP+ CAF in cancer. We reached a high resolution at single-cell level, which enabled us to identify specific clusters associated with immunosuppression and immunotherapy resistance. Identification of cluster-specific signatures paves the way for therapeutic options in combination with immunotherapies.
This article is highlighted in the In This Issue feature, p. 1241
Bispecific antibodies (bsAbs) refer to a large family of molecules that recognize two different epitopes or antigens. Although a series of challenges, especially immunogenicity and chain mispairing issues, once hindered the development of bsAbs, they have been gradually overcome with the help of rapidly developing technologies in the past 5 decades. In the meantime, an increasing number of bsAb platforms have been designed to satisfy different clinical demands. Currently, numerous preclinical and clinical trials are underway, portraying a promising future for bsAb-based cancer treatment. Nevertheless, bsAb drugs still face enormous challenges in their application as cancer therapeutics, including tumor heterogeneity and mutational burden, intractable tumor microenvironment (TME), insufficient costimulatory signals to activate T cells, the necessity for continuous injection, fatal systemic side effects, and off-target toxicities to adjacent normal cells. Therefore, we provide several strategies as solutions to these issues, which comprise generating multispecific bsAbs, discovering neoantigens, combining bsAbs with other anticancer therapies, exploiting natural killer (NK)-cell-based bsAbs and producing bsAbs in situ. In this review, we mainly discuss previous and current challenges in bsAb development and underscore corresponding strategies, with a brief introduction of several typical bsAb formats.
The tumor microenvironment (TME) provides necessary nutrition for tumor growth and recruits immunosuppressive factors including regulatory T cells and myeloid-derived suppressor cells (MDSCs) to inhibit the anti-tumor immune response induced by immunotherapy. As a main TME component, cancer associated fibroblasts (CAFs) can restrain T cell infiltration and activity through extracellular matrix remodeling. Vaccines targeting fibroblast-activating protein α (FAPα), which is mainly expressed on the CAF surface, can eliminate CAFs in tumors and regulate the TME, enhancing the potency of T cell-mediated anti-tumor effects. However, the anti-tumor effects were not fully realized as the tumor induces a large number of peripheral MDSCs during its growth, rendering the body of mice in an immunosuppressive state and preventing the vaccine from inducing effective anti-tumor immune responses. Here, we developed a dual-targeted DNA vaccine OsFS, targeting tumor matrix antigen FAPα and tumor cell antigen survivin simultaneously, exhibited enhanced antineoplastic effects in an established breast cancer model. Moreover, doxorubicin (Dox) pretreatment to remove the peripheral MDSCs induced to regulate the peripheral immune environment could further facilitate the anti-tumor activity of the vaccine. These results indicated that combination treatment of the tumor cells and the TME dual-targeting vaccine plus Dox could effectively realize the anti-tumor activity of the vaccine by decreasing immunosuppressive factors and inducing more tumor-infiltrating lymphocytes, which may offer important guidance for clinical research regarding the combination of the DNA vaccine with low-dose Dox.
Significance
The work provides a conceptual advance in functionally defining the cross talk of tumor epithelia with cancer-associated fibroblastic cells contributing to tumor progression and therapeutic resistance. Independent of protein-based signaling molecules, prostate cancer cells secreted mitochondrial DNA to induce associated fibroblasts to generate anaphylatoxin C3a to support tumor progression in a positive feedback loop. Interestingly, the standard of care chemotherapy, docetaxel, used to treat castrate-resistant prostate cancer was found to further potentiate this paracrine-signaling axis to mediate therapeutic resistance. Blocking anaphylatoxin C3a signaling cooperatively sensitized prostate cancer tumors to docetaxel. We reveal that docetaxel resistance is not a cancer cell-autonomous phenomena and that targeting an immune modulator derived from cancer-associated fibroblasts can limit the expansion of docetaxel-resistant tumors.
The tumour microenvironment comprises a diverse range of cells, including fibroblasts, immune cells and endothelial cells, along with extracellular matrix. In particular, fibroblasts are of significant interest as these cells are reprogrammed during tumourigenesis to become cancer‐associated fibroblasts (CAFs), which in turn support cancer cells growth. MicroRNAs (miRNAs) have been shown to be involved in this intercellular crosstalk in humans. To assess whether miRNAs are also involved in the activation of fibroblasts in dogs, we co‐cultured primary canine skin fibroblasts with the canine mast cell tumour cell line C2 directly or with C2‐derived exosomes, and measured differential abundance of selected miRNAs. Expression of the CAF markers alpha‐smooth muscle actin (ACTA2) and stanniocalcin 1 (STC1) confirmed the activation of our fibroblasts after co‐culture. We show that fibroblasts displayed significant downregulation of miR‐27a and let‐7 family members. These changes correlated with significant upregulation of predicted target mRNAs. Furthermore, RNAi knockdown of miR‐27a revealed that cyclin G1 (CCNG1) exhibited negative correlation at the mRNA and protein level, suggesting that CCNG1 is a target of miR‐27a in canine fibroblasts and involved in their activation. Importantly, miR‐27a knockdown itself resulted in fibroblast activation, as demonstrated by formation of ACTA2 filaments. In addition, interleukin 6 (IL6) was strongly induced in our fibroblasts when co‐cultured, indicating potential reciprocal signalling. Taken together, our findings are consistent with canine fibroblasts being reprogrammed into CAFs to further support cancer development, and that downregulation of miR‐27a may play an important role in the tumour microenvironment crosstalk.
Background:
Ferroptosis is a novel mode of non-apoptotic cell death induced by build-up of toxic lipid peroxides (lipid-ROS) in an iron dependent manner. Cancer-associated fibroblasts (CAFs) support tumor progression and drug resistance by secreting various bioactive substances, including exosomes. Yet, the role of CAFs in regulating lipid metabolism as well as ferroptosis of cancer cells is still unexplored and remains enigmatic.
Methods:
Ferroptosis-related genes in gastric cancer (GC) were screened by using mass spectrum; exosomes were isolated by ultra-centrifugation and CAF secreted miRNAs were determined by RT-qPCR. Erastin was used to induce ferroptosis, and ferroptosis levels were evaluated by measuring lipid-ROS, cell viability and mitochondrial membrane potential.
Results:
Here, we provide clinical evidence to show that arachidonate lipoxygenase 15 (ALOX15) is closely related with lipid-ROS production in gastric cancer, and that exosome-miR-522 serves as a potential inhibitor of ALOX15. By using primary stromal cells and cancer cells, we prove that exosome-miR-522 is mainly derived from CAFs in tumor microenvironment. Moreover, heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) was found to mediate miR-522 packing into exosomes, and ubiquitin-specific protease 7 (USP7) stabilizes hnRNPA1 through de-ubiquitination. Importantly, cisplatin and paclitaxel promote miR-522 secretion from CAFs by activating USP7/hnRNPA1 axis, leading to ALOX15 suppression and decreased lipid-ROS accumulation in cancer cells, and ultimately result in decreased chemo-sensitivity.
Conclusions:
The present study demonstrates that CAFs secrete exosomal miR-522 to inhibit ferroptosis in cancer cells by targeting ALOX15 and blocking lipid-ROS accumulation. The intercellular pathway, comprising USP7, hnRNPA1, exo-miR-522 and ALOX15, reveals new mechanism of acquired chemo-resistance in GC.
Cancer-associated fibroblasts (CAFs) represent a functionally heterogenous population of activated fibroblasts that constitutes a major component of tumor stroma. Although CAFs have been shown to promote tumor growth and mediate resistance to chemotherapy, the mechanisms by which they may contribute to immune suppression within the tumor microenvironment (TME) in lung squamous cell carcinoma (LSCC) remain largely unexplored. Here, we identified a positive correlation between CAF and monocytic myeloid cell abundances in 501 primary LSCCs by mining TCGA datasets. We further validated this finding in an independent cohort using imaging mass cytometry and found a significant spatial interaction between CAFs and monocytic myeloid cells in the TME. To delineate the interplay between CAFs and monocytic myeloid cells, we used chemotaxis assays to show that LSCC patient-derived CAFs promoted recruitment of CCR2+ monocytes via CCL2, which could be reversed by CCR2 inhibition. Using a three-dimensional culture system, we found that CAFs polarized monocytes to adopt a myeloid-derived suppressor cell (MDSC) phenotype, characterized by robust suppression of autologous CD8+ T-cell proliferation and IFNγ production. We further demonstrated that inhibiting IDO1 and NADPH oxidases, NOX2 and NOX4, restored CD8+ T-cell proliferation by reducing reactive oxygen species (ROS) generation in CAF-induced MDSCs. Taken together, our study highlights a pivotal role of CAFs in regulating monocyte recruitment and differentiation and demonstrated that CCR2 inhibition and ROS scavenging abrogate the CAF-MDSC axis, illuminating a potential therapeutic path to reversing the CAF-mediated immunosuppressive microenvironment.
The roles of cancer-associated fibroblasts (CAFs) in the progression of various types of cancers are well established. CAFs promote cancer progression through pleiotropic mechanisms, including the secretion of soluble factors and extracellular matrix, physical interactions with cancer cells, and the regulation of angiogenesis, immunity, and metabolism. Their contribution to therapeutic resistance is also well appreciated. Therefore, CAFs have been considered as a therapeutic target in cancer. However, recent studies in autochthonous pancreatic cancer models suggest that specific subset(s) of CAFs exhibit cancer-restraining roles, indicating that CAFs are functionally and molecularly heterogeneous, which is supported by recent single-cell transcriptome analyses. While cancer-promoting CAFs (pCAFs) have been extensively studied, the nature and specific marker(s) of cancer-restraining CAFs (rCAFs) have remained uncharacterized. Interestingly, a recent study provided insights into the nature of rCAFs and suggested that they may share molecular properties with pancreatic stellate cells (PSCs) and mesenchymal stem/stromal cells (MSCs). Complicating this finding is that PSCs and MSCs have been shown to promote the formation of a tumor-permissive and tumor-promoting environment in xenograft tumor models. However, these cells undergo significant transcriptional and epigenetic changes during ex-vivo culture, which confounds the interpretation of experimental results based on the use of cultured cells. In this short review, we describe recent studies and hypotheses on the identity of rCAFs and discuss their analogy to fibroblasts that suppress fibrosis in fibrotic diseases. Finally, we discuss how these findings can be exploited to develop novel anticancer therapies in the future.
Cancer-associated fibroblasts (CAFs) are the most abundant cell type in the tumor microenvironment and are responsible for producing the desmoplastic reaction that is a poor prognostic factor in ovarian cancer. Long non-coding RNAs (lncRNAs) have been shown to play important roles in cancer. However, very little is known about the role of lncRNAs in the tumor microenvironment. We aimed to identify lncRNAs expressed in ovarian CAFs that were associated with patient survival and used computational approaches to predict their function. Increased expression of 9 lncRNAs and decreased expression of 1 lncRNA in ovarian CAFs were found to be associated with poorer overall survival. A "guilt-by-association" approach was used to predict the function of these lncRNAs. In particular, MIR155HG was predicted to play a role in immune response. Further investigation revealed high MIR155HG expression to be associated with higher infiltrates of immune cell subsets. In conclusion, these data demonstrate expression on several lncRNAs in CAFs are associated with patient survival, and are likely to play an important roles in regulating CAF function.
The tumour microenvironment (TME) determines vital aspects of tumour development, such as tumour growth, metastases and response to therapy. Cancer-associated fibroblasts (CAFs) are abundant and extremely influential in this process and interact with cellular and matrix TME constituents such as endothelial and immune cells and collagens, fibronectin and elastin, respectively. However, CAFs are also the recipients of signals—both chemical and physical—that are generated by the TME, and their phenotype effectively evolves alongside the tumour mass during tumour progression. Amid a rising clinical interest in CAFs as a crucial force for disease progression, this review aims to contextualise the CAF phenotype using the chronological framework of the CAF life cycle within the evolving tumour stroma, ranging from quiescent fibroblasts to highly proliferative and secretory CAFs. The emergence, properties and clinical implications of CAF activation are discussed, as well as research strategies used to characterise CAFs and current clinical efforts to alter CAF function as a therapeutic strategy.
Background:
Although accumulating evidence suggests that the crosstalk between malignant cells and cancer-associated fibroblasts (CAFs) actively contributes to tumour growth and metastatic dissemination, therapeutic strategies targeting tumour stroma are still not common in the clinical practice. Metal-based nanomaterials have been shown to exert excellent cytotoxic and anti-cancerous activities, however, their effects on the reactive stroma have never been investigated in details. Thus, using feasible in vitro and in vivo systems to model tumour microenvironment, we tested whether the presence of gold, silver or gold-core silver-shell nanoparticles exerts anti-tumour and metastasis suppressing activities by influencing the tumour-supporting activity of stromal fibroblasts.
Results:
We found that the presence of gold-core silver-shell hybrid nanomaterials in the tumour microenvironment attenuated the tumour cell-promoting behaviour of CAFs, and this phenomenon led to a prominent attenuation of metastatic dissemination in vivo as well. Mechanistically, transcriptome analysis on tumour-promoting CAFs revealed that silver-based nanomaterials trigger expressional changes in genes related to cancer invasion and tumour metastasis.
Conclusions:
Here we report that metal nanoparticles can influence the cancer-promoting activity of tumour stroma by affecting the gene expressional and secretory profiles of stromal fibroblasts and thereby altering their intrinsic crosstalk with malignant cells. This potential of metal nanomaterials should be exploited in multimodal treatment approaches and translated into improved therapeutic outcomes.
Although fibroblast heterogeneity is recognized in primary tumors, both its characterization in and its impact on metastases remain unknown. Here, combining flow cytometry, immunohistochemistry and RNA-sequencing on breast cancer samples, we identify four Cancer-Associated Fibroblast (CAF) subpopulations in metastatic lymph nodes (LN). Two myofibroblastic subsets, CAF-S1 and CAF-S4, accumulate in LN and correlate with cancer cell invasion. By developing functional assays on primary cultures, we demonstrate that these subsets promote metastasis through distinct functions. While CAF-S1 stimulate cancer cell migration and initiate an epithelial-to-mesenchymal transition through CXCL12 and TGFβ pathways, highly contractile CAF-S4 induce cancer cell invasion in 3-dimensions via NOTCH signaling. Patients with high levels of CAFs, particularly CAF-S4, in LN at diagnosis are prone to develop late distant metastases. Our findings suggest that CAF subset accumulation in LN is a prognostic marker, suggesting that CAF subsets could be examined in axillary LN at diagnosis. Cancer associated fibroblasts are known to promote the progression of cancer. Here, the authors show that two particular subsets of cancer associated fibroblasts induce metastasis but work via distinct mechanisms including, chemokine signalling and Notch signalling.
Regulatory T cells (Treg) are abundant in human and mouse pancreatic cancer. To understand the contribution to the immunosuppressive microenvironment, we depleted Tregs in a mouse model of pancreatic cancer. Contrary to our expectations, Treg depletion failed to relieve immunosuppression and led to accelerated tumor progression. We show that Tregs are a key source of TGFβ ligands and, accordingly, their depletion reprogramed the fibroblast population, with loss of tumor-restraining, smooth muscle actin–expressing fibroblasts. Conversely, we observed an increase in chemokines Ccl3, Ccl6, and Ccl8 leading to increased myeloid cell recruitment, restoration of immune suppression, and promotion of carcinogenesis, an effect that was inhibited by blockade of the common CCL3/6/8 receptor CCR1. Further, Treg depletion unleashed pathologic CD4+ T-cell responses. Our data point to new mechanisms regulating fibroblast differentiation in pancreatic cancer and support the notion that fibroblasts are a heterogeneous population with different and opposing functions in pancreatic carcinogenesis.
Significance
Here, we describe an unexpected cross-talk between Tregs and fibroblasts in pancreatic cancer. Treg depletion resulted in differentiation of inflammatory fibroblast subsets, in turn driving infiltration of myeloid cells through CCR1, thus uncovering a potentially new therapeutic approach to relieve immunosuppression in pancreatic cancer.
See related commentary by Aykut et al., p. 345.
This article is highlighted in the In This Issue feature, p. 327
Background:
Ovarian cancer (OC) is a gynecological malignancy with a high mortality. Cisplatin-based treatment is the typical treatment regimen for OC patients; however, it may cause unfavorable resistance. The current study intends to explore the function of cancer-associated fibroblast (CAF)-derived exosomal microRNA-98-5p (miR-98-5p) in cisplatin resistance in OC, and the participation of CDKN1A.
Methods:
Bioinformatics analysis was employed in order to obtain cisplatin resistance-related differential genes in OC as well as possible upstream regulatory miRs. After gain- and loss-of-function assays in OC cells, RT-qPCR and western blot analysis were employed to measure CDKN1A and miR-98-5p expression. Dual luciferase reporter assay was applied to verify the targeting relationship between miR-98-5p and CDKN1A. CAFs were treated with miR-98-5p inhibitor, and then exosomes were isolated and co-cultured with OC cells. CCK-8, colony formation and flow cytometry assays were conducted to assess cell proliferation, cell colony formation, cell cycle distribution and cell apoptosis, respectively. At last, xenograft tumor in nude mice was carried out to test whether exosomal miR-98-5p could affect cisplatin resistance in OC in vivo.
Results:
CDKN1A was highly expressed in cisplatin-sensitive OC cell lines, and silencing CDKN1A significantly promoted proliferation and cell cycle entry but decreased apoptosis in cisplatin-sensitive OC cells. miR-98-5p targeted CDKN1A to inhibit CDKN1A expression. CAF-derived exosomal miR-98-5p increased OC cell proliferation and cell cycle entry, but suppressed cell apoptosis. Furthermore, exosomal miR-98-5p promoted cisplatin resistance and downregulated CDKN1A in nude mice.
Conclusion:
Collectively, CAF-derived exosomes carrying overexpressed miR-98-5p promote cisplatin resistance in OC by downregulating CDKN1A.
Multiple studies have shown that cancer‐associated fibroblasts (CAFs) play an important role in tumour progression, including carcinogenesis, invasion, metastasis and the chemoresistance of cancer cells. Immune cells, including macrophages, natural killer cells, dendritic cells and T cells, play a dual role in the tumour microenvironment. Although increasing research has focused on studying interactions between distinct cells in the tumour microenvironment, the complex relationships between CAFs and immune cells remain unclear and need further study. Here, we summarize our current understanding of crosstalk between CAFs and immune cells, which may help clarify their diagnostic and therapeutic value in tumour progression.
Cancer-Associated Fibroblasts (CAFs) were shown to orchestrate tumour-promoting inflammation in multiple malignancies, including breast cancer. However, the molecular pathways that govern the inflammatory role of CAFs are poorly characterised. In this study we found that fibroblasts sense damage-associated molecular patterns (DAMPs), and in response activate the NLRP3 inflammasome pathway, resulting in instigation of pro-inflammatory signalling and secretion of IL-1β. This upregulation was evident in CAFs in mouse and in human breast carcinomas. Moreover, CAF-derived inflammasome signalling facilitated tumour growth and metastasis, which was attenuated when NLRP3 or IL-1β were specifically ablated. Functionally, CAF-derived inflammasome promoted tumour progression and metastasis by modulating the tumour microenvironment towards an immune suppressive milieu and by upregulating the expression of adhesion molecules on endothelial cells. Our findings elucidate a mechanism by which CAFs promote breast cancer progression and metastasis, by linking the physiological tissue damage response of fibroblasts with tumour-promoting inflammation.
Purpose:
To characterize expression of neuregulin-1 (NRG1), an HER3 ligand, in HER2-positive breast cancer and its relation with the efficacy of trastuzumab with or without pertuzumab.
Experimental design:
Characterization of NRG1 expression in tumor cell lines, in tumor specimens, and in cancer-associated fibroblasts (CAFs). Patient-derived CAFs were used to investigate NRG1 impact on the activity of trastuzumab with or without pertuzumab in HER2-positive breast cancer cells. The relationship between NRG1 expression and pathologic response to anti-HER2-based neoadjuvant therapy was assessed in a retrospective patient cohort and in the NeoSphere trial.
Results:
NRG1 was expressed in HER2-positive breast cancer-derived fibroblasts at significantly higher levels than in cancer cells. NRG1 and the conditioned media (CM) from CAFs phosphorylated HER3 and AKT in cancer cells and mediated trastuzumab resistance. Stable genetic depletion of NRG1 from CAFs overcame trastuzumab resistance. Pertuzumab effectively suppressed trastuzumab resistance mediated by either NRG1 or CAF's CM. NRG1 engaged an epithelial-to-mesenchymal transition that was prevented by trastuzumab and pertuzumab. In clinical samples, stromal and/or tumor cell expression of NRG1 determined by immunohistochemistry was uncommon (13.2%) yet significantly linked with residual disease following trastuzumab-based neoadjuvant therapy. In the NeoSphere trial, the magnitude of the difference of pathologic complete response rates favoring the pertuzumab arm was higher in the NRG1-high group.
Conclusions:
CAF-derived NRG1 mediates trastuzumab resistance through HER3/AKT, which might be reverted by pertuzumab. In patients with HER2-positive breast cancer, high expression of NRG1 was associated to poor response to trastuzumab, but not in combination with pertuzumab.
Fibroblasts display extensive transcriptional heterogeneity, yet functional annotation and characterization of their heterocellular relationships remains incomplete. Using mass cytometry, we chart the stromal composition of 18 murine tissues and 5 spontaneous tumor models, with an emphasis on mesenchymal phenotypes. This analysis reveals extensive stromal heterogeneity across tissues and tumors, and identifies coordinated relationships between mesenchymal and immune cell subsets in pancreatic ductal adenocarcinoma. Expression of CD105 demarks two stable and functionally distinct pancreatic fibroblast lineages, which are also identified in murine and human healthy tissues and tumors. Whereas CD105-positive pancreatic fibroblasts are permissive for tumor growth in vivo, CD105-negative fibroblasts are highly tumor suppressive. This restrictive effect is entirely dependent on functional adaptive immunity. Collectively, these results reveal two functionally distinct pancreatic fibroblast lineages and highlight the importance of mesenchymal and immune cell interactions in restricting tumor growth.
Drug resistance remains the major obstacle limiting the effectiveness of chemotherapy for esophageal squamous cell carcinoma (ESCC)[1]. However, how stromal cells cooperate with immune cells to contribute to drug resistance is not yet fully understood. In this study, we observed that monocytic myeloid-derived suppressor cells (M-MDSCs) were correlated with cisplatin resistance in patients with ESCC. Furthermore, CAFs promoted differentiation of monocytes into M-MDSCs phenotypically and functionally in vitro. Mechanically, both interleukin (IL)-6 and exosome-packed microRNA-21 (miR-21) secreted by CAFs synergistically promoted the generation of M-MDSCs via activating the signal transducing activator of transcription 3 (STAT3) by IL-6 in an autocrine manner. Combined blocking of IL-6 receptor and inhibition of miR-21 significantly reversed CAF-mediated M-MDSC generation. Notably, the effects of CAFs on M-MDSC induction were abolished by inhibiting STAT3 signaling. Functionally, CAF-induced M-MDSCs promoted drug resistance of tumor cells upon cisplatin treatment. Clinically, ESCC patients with high infiltration of CAFs and CD11b⁺ myeloid cells had unfavorable predicted overall survival both in our cohort and in TCGA data. Taken together, our study reveals a paracrine and autocrine of IL-6 caused by CAFs co-activate STAT3 signaling, promoting the generation of M-MDSCs, and highlights the important role of CAFs in cooperation with M-MDSCs in promoting drug resistance, thus providing potential opportunities for reversing drug resistance through inhibition of STAT3 signaling.
Cancer-associated fibroblasts (CAFs) can promote the development and me-tastasis of prostate cancer partly by mediating tumor-associated inflammation. An increasing amount of studies have focused on the functional interactions between CAFs and immune cells in the tumor microenvironment (TME). We previously reported that G protein-coupled receptor 30 (GPR30) was highly expressed in prostate CAFs and plays a crucial role in prostate stromal cell activation. However, the effect and underlying mechanism of GPR30 expression in prostate CAFs affecting the interaction between CAFs and tumor-associated macrophages (TAMs) need further elucidation. Here, we found that, compared with CAF-shControl, CAF-shGPR30 inhibited macro-phage migration through transwell migration assays, which should be attributed to the decreased expression of C-X-C motif chemokine ligand 12 (CXCL12). In addition, macrophages treated with a culture medium of CAF-shGPR30 exhibited attenuated M2 polarization with downregulated M2-like markers expression. Moreover, macrophages stimulated with a culture medium of CAF-shGPR30 were less efficient in promoting activation of fibroblast cells and invasion of PCa cells. Finally, cocultured CAF-shGPR30 and mac-rophages suppressed PCa cell invasion compared to cocultured CAF
Background & aims:
Carcinoma-associated fibroblasts (CAFs) are key players in multicellular, stromal-dependent alterations leading to HCC pathogenesis. However, the intricate crosstalk between CAFs and other components in the tumor microenvironment (TME) remains unclear. This study aimed to investigate the novel cellular crosstalk among CAFs, tumor cells, and tumor-associated neutrophils (TANs) during different stages of HCC pathogenesis.
Approach & results:
In the HCC-TME, CAF-derived cardiotrophin-like cytokine factor 1 (CLCF1) increased CXCL6 and TGF-β secretion in tumor cells, which subsequently promoted tumor cell stemness in an autocrine manner and TAN infiltration and polarization in a paracrine manner. Moreover, CXCL6 and TGF-β secreted by HCC cells activated ERK1/2 signaling of CAFs to produce more CLCF1, thus forming a positive feedback loop to accelerate HCC progression. Inhibition of ERK1/2 or CLCF1/ciliary neurotrophic factor receptor (CNTFR) signaling efficiently impaired CLCF1-mediated crosstalk among CAFs, tumor cells, and TANs both in vitro and in vivo. In clinical samples, upregulation of the CLCF1-CXCL6/TGF-β axis exhibited a marked correlation with increased cancer stem cells, "N2"-polarized TANs, tumor stage, and poor prognosis.
Conclusions:
This study reveals a novel cytokine-mediated cellular crosstalk and clinical network involving the CLCF1-CXCL6/TGF-β axis, which regulates the positive feedback loop among CAFs, tumor stemness, and TANs, HCC progression, and patient prognosis. These results may support the CLCF1 cascade as a potential prognostic biomarker and suggest that selective blockade of CLCF1/CNTFR or ERK1/2 signaling could provide an effective therapeutic target for HCC patients.
Pancreatic ductal adenocarcinoma (PDAC) has a poor 5-year survival rate and lacks effective therapeutics. Therefore, it is of paramount importance to identify new targets. Using multiplex data from patient tissue, three-dimensional coculturing in vitro assays, and orthotopic murine models, we identified Netrin G1 (NetG1) as a promoter of PDAC tumorigenesis. We found that NetG1+ cancer-associated fibroblasts (CAF) support PDAC survival, through a NetG1-mediated effect on glutamate/glutamine metabolism. Also, NetG1+ CAFs are intrinsically immunosuppressive and inhibit natural killer cell–mediated killing of tumor cells. These protumor functions are controlled by a signaling circuit downstream of NetG1, which is comprised of AKT/4E-BP1, p38/FRA1, vesicular glutamate transporter 1, and glutamine synthetase. Finally, blocking NetG1 with a neutralizing antibody stunts in vivo tumorigenesis, suggesting NetG1 as potential target in PDAC.
Significance
This study demonstrates the feasibility of targeting a fibroblastic protein, NetG1, which can limit PDAC tumorigenesis in vivo by reverting the protumorigenic properties of CAFs. Moreover, inhibition of metabolic proteins in CAFs altered their immunosuppressive capacity, linking metabolism with immunomodulatory function.
See related commentary by Sherman, p. 230.
This article is highlighted in the In This Issue feature, p. 211
Leucine-rich repeat containing 15 (LRRC15) is a member of the leucine-rich repeat superfamily that is overexpressed in various cancers and associated with higher tumor grade and aggression. Despite its known tumorigenicity, its roles within osteosarcoma are unknown, prompting us to evaluate its expression and clinical significance within this rare yet aggressive cancer. Western blots showed a differential expression of LRRC15 in the osteosarcoma cell lines MNNG/HOS, KHOS, 143B, MG63, Saos-2, and U2OS. We additionally validated this positive expression, as well as sublocalization to the cell membrane, with immunofluorescence. A tissue microarray (TMA) constructed from 69 osteosarcoma patient tissues was immunohistochemically stained for LRRC15 expression, stratified, and used for clinicopathological analysis. Publicly available databases on LRRC15 expression, including RNA sequencing (RNA-Seq) data from the Therapeutically Applicable Research to Generate Effective Treatments on Osteosarcoma (TARGET-OS) and the Gene Expression database of Normal and Tumor tissues 2 (GENT2) were also analyzed. We found 63 of the 69 (91.3%) patient tissues exhibited some degree of LRRC15 immunostaining, including no staining (6 of 69, 8.7%), 1+ staining (12 of 69, 17.4%), 2+ staining (25 of 69, 36.2%), and 3+ staining (26 of 69, 37.7%). The patients with osteosarcomas having elevated LRRC15 expression demonstrated comparatively increased metastasis, chemoresistance, and shorter 5-year survival rates. Our analysis of the TARGET-OS and GENT2 databases also showed increased LRRC15 gene expression in osteosarcoma. Taken together, our study supports LRRC15 as a prognostic biomarker and emerging therapeutic target in osteosarcoma. This article is protected by copyright. All rights reserved.
Despite the development of second-generation antiandrogens, acquired resistance to hormone therapy remains a major challenge in treating advanced prostate cancer. We find that cancer-associated fibroblasts (CAFs) can promote antiandrogen resistance in mouse models and in prostate organoid cultures. We identify neuregulin 1 (NRG1) in CAF supernatant, which promotes resistance in tumor cells through activation of HER3. Pharmacological blockade of the NRG1/HER3 axis using clinical-grade blocking antibodies re-sensitizes tumors to hormone deprivation in vitro and in vivo. Furthermore, patients with castration-resistant prostate cancer with increased tumor NRG1 activity have an inferior response to second-generation antiandrogen therapy. This work reveals a paracrine mechanism of antiandrogen resistance in prostate cancer amenable to clinical testing using available targeted therapies.
Various factors in the tumor microenvironment (TME) regulate the expression of PD-L1 in carcinoma cells. The cancer-associated fibroblasts (CAFs) play a crucial role in regulating and rewiring TME to enhance their immune suppressive function and to favor the invasion of the malignant cells. Tumor progression may be retarded by targeting CAFs in the TME. Various studies highlighted the ability of targeting CAF with pirfenidone (PFD), leading to increased efficacy of chemotherapy. However, its potential for the reduction of immune-suppression capacity of CAFs remains to be elusive. Here, we assessed the effect of PFD on the expression of PD-L1 on CAF cells. Besides migration inhibitory effects of PFD on CAFs, the expression level of PD-L1 reduced in CAFs after treatment with PFD. The downstream analysis of released cytokines from CAFs showed that PFD significantly dropped the secretion of CCL17 and TNF-β, where a positive association between PFD-targeted proteins and PD-L1 was observed. These data suggest that the treatment of CAF within TME through the PFD may reduce the acquisition of CAF-mediated invasive and immune-suppressive capacity of breast carcinoma cells.
Background
The unique ability of NK cells to target cancer cells without antigen specificity makes them an attractive prospect for immunotherapy of solid tumors. However, the complexity of the tumor microenvironment (TME), particularly its heterogeneity and associated immunosuppressive properties, enables solid tumor cells to escape NK cell immune-surveillance by impairing their infiltration and cytotoxic functions. As a result, NK cells that have been able to infiltrate solid tumors are dysfunctional, exhausted and metabolically and functionally impaired. Understanding the status of NK cells in solid tumors and the interplay between the tumor-promoting functions of the TME and the immunometabolic reprogramming events that NK cells endure as a result is essential to developing approaches to improve the clinical outcome of NK cell-based immunotherapies against solid tumors.Conclusions
In this review, we address the current knowledge on the presence and immunometabolic roles of NK cells in solid tumors as well as the strategies developed to restore NK cell activities in these conditions, with the ultimate goal of enhancing persistence, trafficking, cytotoxicity and metabolic functions.
Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related mortality in the Western world with limited therapeutic options and dismal long-term survival. The neoplastic epithelium exists within a dense stroma, which is recognized as a critical mediator of disease progression through direct effects on cancer cells and indirect effects on the tumour immune microenvironment. The three dominant entities in the PDAC stroma are extracellular matrix (ECM), vasculature and cancer-associated fibroblasts (CAFs). The ECM can function as a barrier to effective drug delivery to PDAC cancer cells, and a multitude of strategies to target the ECM have been attempted in the past decade. The tumour vasculature is a complex system and, although multiple anti-angiogenesis agents have already failed late-stage clinical trials in PDAC, other vasculature-targeting approaches aimed at vessel normalization and tumour immunosensitization have shown promise in preclinical models. Lastly, PDAC CAFs participate in active cross-talk with cancer cells within the tumour microenvironment. The existence of intratumoural CAF heterogeneity represents a paradigm shift in PDAC CAF biology, with myofibroblastic and inflammatory CAF subtypes that likely make distinct contributions to PDAC progression. In this Review, we discuss our current understanding of the three principal constituents of PDAC stroma, their effect on the prevalent immune landscape and promising therapeutic targets within this compartment.
Currently, clinically-used anti-tumor nanomedicine is usually insufficient to eradicate malignancies, due to the tumor stroma exerting therapeutic resistance and physical barriers for a proper drug delivery. As the most abundant cells in tumor stroma, cancer-associated fibroblasts (CAFs) produce a critical tumor-promoting effect and barriers preventing the physical delivery of nanomedicines through secreting pro-tumorigenic cytokines, increasing solid tumor pressure and interstitial fluid pressure (IFP), and non-specific internalization. Therefore, beyond treatment centered on cancer cells, researchers are focusing on targeting CAFs to fight stromal-rich tumors. In recent years, a series of novel nano delivery systems have been developed based on specific CAF-targeted ligands and advanced biofunctional materials. On the one hand, CAF-targeted nano delivery systems inhibit the pro-tumor signaling pathway between CAFs and cancer cells to reverse tumorigenesis, immunosuppression or drug resistance in the tumor microenvironment, thus improving the sensitivity to anti-tumor treatments. On the other hand, nano-strategies acting on CAFs profoundly contribute on increasing the deep penetration of anti-tumor drugs through the decrease of solid pressure, IFP and dense extracellular matrix generation related to the resistance to intratumoral diffusion. In this review, we firstly introduce the biological mechanisms of CAFs that interfere with nanotherapy. The state-of-the-art passive and active strategies of nano delivery systems targeting CAFs are then summarized, focusing on the therapeutic mechanism involved and rational design of nano delivery systems. Additionally, the challenges of CAF-targeted nanotherapy are discussed from the perspectives of developing efficient nano delivery systems and potential clinical use.
Determining mechanisms of resistance to αPD-1/PD-L1 immune-checkpoint immunotherapy is key to developing new treatment strategies. Cancer-associated fibroblasts (CAF) have many tumor-promoting functions and promote immune evasion through multiple mechanisms, but as yet, no CAF-specific inhibitors are clinically available. Here we generated CAF-rich murine tumor models (TC1, MC38, and 4T1) to investigate how CAFs influence the immune microenvironment and affect response to different immunotherapy modalities [anticancer vaccination, TC1 (HPV E7 DNA vaccine), αPD-1, and MC38] and found that CAFs broadly suppressed response by specifically excluding CD8+ T cells from tumors (not CD4+ T cells or macrophages); CD8+ T-cell exclusion was similarly present in CAF-rich human tumors. RNA sequencing of CD8+ T cells from CAF-rich murine tumors and immunochemistry analysis of human tumors identified significant upregulation of CTLA-4 in the absence of other exhaustion markers; inhibiting CTLA-4 with a nondepleting antibody overcame the CD8+ T-cell exclusion effect without affecting Tregs. We then examined the potential for CAF targeting, focusing on the ROS-producing enzyme NOX4, which is upregulated by CAF in many human cancers, and compared this with TGFβ1 inhibition, a key regulator of the CAF phenotype. siRNA knockdown or pharmacologic inhibition [GKT137831 (Setanaxib)] of NOX4 “normalized” CAF to a quiescent phenotype and promoted intratumoral CD8+ T-cell infiltration, overcoming the exclusion effect; TGFβ1 inhibition could prevent, but not reverse, CAF differentiation. Finally, NOX4 inhibition restored immunotherapy response in CAF-rich tumors. These findings demonstrate that CAF-mediated immunotherapy resistance can be effectively overcome through NOX4 inhibition and could improve outcome in a broad range of cancers.
Significance
NOX4 is critical for maintaining the immune-suppressive CAF phenotype in tumors. Pharmacologic inhibition of NOX4 potentiates immunotherapy by overcoming CAF-mediated CD8+ T-cell exclusion.
With only a fraction of patients responding to cancer immunotherapy, a better understanding of the entire tumor microenvironment is needed. Using single-cell transcriptomics, we chart the fibroblastic landscape during pancreatic ductal adenocarcinoma (PDAC) progression in animal models. We identify a population of carcinoma-associated fibroblasts (CAF) that are programmed by TGFβ and express the leucine-rich repeat containing 15 (LRRC15) protein. These LRRC15+ CAFs surround tumor islets and are absent from normal pancreatic tissue. The presence of LRRC15+ CAFs in human patients was confirmed in >80,000 single cells from 22 patients with PDAC as well as by using IHC on samples from 70 patients. Furthermore, immunotherapy clinical trials comprising more than 600 patients across six cancer types revealed elevated levels of the LRRC15+ CAF signature correlated with poor response to anti–PD-L1 therapy. This work has important implications for targeting nonimmune elements of the tumor microenvironment to boost responses of patients with cancer to immune checkpoint blockade therapy.
Significance
This study describes the single-cell landscape of CAFs in pancreatic cancer during in vivo tumor evolution. A TGFβ-driven, LRRC15+ CAF lineage is associated with poor outcome in immunotherapy trial data comprising multiple solid-tumor entities and represents a target for combinatorial therapy.
This article is highlighted in the In This Issue feature, p. 161