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Summary of the proposed mechanism of action by the drug combination. The combination treatment of BETinhibitors and BH3-mimetics causes a stress response with an increase of ATF4 and subsequent up regulation of pro-apoptotic Noxa, interfering with Mcl-1 function, leading to induction of apoptosis.
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Drug combination therapies remain pivotal for the treatment of heterogeneous malignancies, such as glioblastomas. Here, we show a novel lethal interaction between Bcl-xL and c-myc inhibition accomplished by bromodomain protein inhibitors. Established, patient-derived xenograft and stem cell-like glioma cells were treated with the novel bromodomain...
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Deguelin, a rotenoid extracted from Mundulea sericea (Leguminosae), exhibits antitumor effects on several types of human cancers. Due to the limited studies of deguelin on colorectal cancer (CRC), the present study was designed to investigate the antitumor effect of deguelin and to explore the underlying mechanism in CRC.
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... Although BH3-mimetics have been shown to be effective in certain cancers, there are still considerable variations in the sensitivity of different cancer cells to these drugs 23 . To date, little is known about the relevance of Bcl-2 family members in GSC responsiveness to chemotherapeutic agents 27 . For this reason, in this study, we evaluated the role of Bcl-2 family members in the regulation of cancer stem cell survival in a panel of six GSC-ECLs using in vitro assays. ...
The recurrence of Glioblastoma is partly attributed to the highly resistant subpopulation of glioma stem cells. A novel therapeutic approach focuses on restoring apoptotic programs in these cancer stem cells, as they are often deregulated. BH3-mimetics, targeting anti-apoptotic Bcl-2 family members, are emerging as promising compounds to sensitize cancer cells to antineoplastic treatments. Herein, we determined that the most abundantly expressed anti-apoptotic Bcl-2 family members, Bcl-xL and Mcl-1, are the most relevant in regulating patient-derived glioma stem cell survival. We exposed these cells to routinely used chemotherapeutic drugs and BH3-mimetics (ABT-263, WEHI-539, and S63845). We observed that the combination of BH3-mimetics targeting Bcl-xL with chemotherapeutic agents caused a marked increase in cell death and that this sensitivity to Bcl-xL inhibition correlated with Noxa expression levels. Interestingly, whereas co-targeting Bcl-xL and Mcl-1 led to massive cell death in all tested cell lines, down-regulation of Noxa promoted cell survival only in cell lines expressing higher levels of this BH3-only. Therefore, in glioma stem cells, the efficacy of Bcl-xL inhibition is closely associated with Mcl-1 activity and Noxa expression. Hence, a potentially effective strategy would consist of combining Bcl-xL inhibitors with chemotherapeutic agents capable of inducing Noxa, taking advantage of this pro-apoptotic factor.
... Combination treatment of TMZ or JQ1 with the BCL-XL inhibitor A1331852 potently kills glioblastoma cells Current standard of care treatment for GBM patients includes chemotherapy with the DNA damage-inducing alkylating agent TMZ [30]. Inhibition of BET (bromodomain and extra-terminal) bromodomain proteins with the small molecule inhibitor JQ1 has been reported to regulate the DNA damage response in several cancer cell lines in vitro, and to promote G1 cell cycle arrest and dissipation of the mitochondrial membrane potential [31][32][33]. Of note, inhibition of BET bromodomain proteins was reported to have anti-tumour effects in mouse models of glioma [34]. ...
... Cotreatment of U87MG and GL261 glioma cells with TMZ and the BET inhibitor JQ1 caused substantial DNA damage and tumour cell killing in vitro and slowed tumour expansion in mice [35]. It was previously shown that combined treatment with JQ1 and the BH3 mimetic ABT-263, a potent inhibitor of BCL-2, BCL-XL and BCL-W, caused substantial apoptosis in glioma cells in vitro, and this was accompanied by an increase in the pro-apoptotic BH3-only protein NOXA and activation of caspases [33,36]. ...
Glioblastoma multiforme (GBM) is the most common and aggressive form of brain cancer, with treatment options often constrained due to inherent resistance of malignant cells to conventional therapy. We investigated the impact of triggering programmed cell death (PCD) by using BH3 mimetic drugs in human GBM cell lines. We demonstrate that co-targeting the pro-survival proteins BCL-XL and MCL-1 was more potent at killing six GBM cell lines compared to conventional therapy with Temozolomide or the bromodomain inhibitor JQ1 in vitro. Enhanced cell killing was observed in U251 and SNB-19 cells in response to dual treatment with TMZ or JQ1 combined with a BCL-XL inhibitor, compared to single agent treatment. This was reflected in abundant cleavage/activation of caspase-3 and cleavage of PARP1, markers of apoptosis. U251 and SNB-19 cells were more readily killed by a combination of BH3 mimetics targeting BCL-XL and MCL-1 as opposed to dual treatment with the BCL-2 inhibitor Venetoclax and a BCL-XL inhibitor. The combined loss of BAX and BAK, the essential executioners of intrinsic apoptosis, rendered U251 and SNB-19 cells refractory to any of the drug combinations tested, demonstrating that apoptosis is responsible for their killing. In an orthotopic mouse model of GBM, we demonstrate that the BCL-XL inhibitor A1331852 can penetrate the brain, with A1331852 detected in both tumour and healthy brain regions. We also investigated the impact of combining small molecule inducers of ferroptosis, erastin and RSL3, with BH3 mimetic drugs. We found that a BCL-XL or an MCL-1 inhibitor potently cooperates with inducers of ferroptosis in killing U251 cells. Overall, these findings demonstrate the potential of dual targeting of distinct PCD signalling pathways in GBM and may guide the utility of BCL-XL inhibitors and inducers of ferroptosis with standard of care treatment for improved therapies for GBM.
... Glioma patients with a high expression of Mcl-1 are associated with tumor recurrence and a shorter survival period [34]. Experimental findings have indicated that Noxa activation is a crucial strategy for overriding Mcl-1-mediated apoptosis resistance [35,36]. Therefore, the imbalance between Noxa and Mcl-1 towards the former will guide the apoptotic program in dipyridamole-treated glioma cells. ...
Elevation of intracellular cAMP levels has been implicated in glioma cell proliferation inhibition, differentiation, and apoptosis. Inhibition of phosphodiesterase is a way to elevate intracellular cAMP levels. The present study aimed to investigate the anti-glioma potential of dipyridamole, an inhibitor of phosphodiesterase. Upon treatment with dipyridamole, human U87 glioma cells decreased cell viability, clonogenic colonization, migration, and invasion, along with Noxa upregulation, Endoplasmic Reticulum (ER) stress, impaired autophagic flux, Yes-associated Protein 1 (YAP1) phosphorylation, and YAP1 reduction. Pharmacological and genetic studies revealed the ability of dipyridamole to initiate Noxa-guided apoptosis through ER stress. Additionally, the current study further identified the biochemical role of YAP1 in communicating with ER stress and autophagy under situations of dipyridamole treatment. YAP1 promoted autophagy and protected glioma cells from dipyridamole-induced apoptotic cell death. Dipyridamole impaired autophagic flux and rendered glioma cells more vulnerable to apoptotic cell death through ER stress-inhibitable YAP1/autophagy axis. The overall cellular changes caused by dipyridamole appeared to ensure a successful completion of apoptosis. Dipyridamole also duplicated the biochemical changes and apoptosis in glioma T98G cells. Since dipyridamole has additional biochemical and pharmacological properties, further research centered on the anti-glioma mechanisms of dipyridamole is still needed.
... Several forms of distinct cell death pathways emerged over the last 50 years. In 1972, programmed cell death, called apoptosis, was described and years after different distinctions of this form of cell death have emerged, such as intrinsic and extrinsic apoptosis [21][22][23][24][25][26]. More recently, autophagyassociated cell death, necrosis, ferroptosis, and pyroptosis have been described [27]. ...
Glioblastoma (GBM), a highly malignant primary brain tumor, inevitably leads to death. In the last decade, a variety of novel molecular characteristics of GBMs were unraveled. The identification of the mutation in the IDH1 and less commonly IDH2 gene was surprising and ever since has nurtured research in the field of GBM metabolism. While initially thought that mutated IDH1 were to act as a loss of function mutation it became clear that it conferred the production of an oncometabolite that in turn substantially reprograms GBM metabolism. While mutated IDH1 represents truly the tip of the iceberg, there are numerous other related observations in GBM that are of significant interest to the field, including the notion that oxidative metabolism appears to play a more critical role than believed earlier. Metabolic zoning is another important hallmark of GBM since it was found that the infiltrative margin that drives GBM progression reveals enrichment of fatty acid derivatives. Consistently, fatty acid metabolism appears to be a novel therapeutic target for GBM. How metabolism in GBM intersects is another pivotal issue that appears to be important for its progression and response and resistance to therapies. In this review, we will summarize some of the most relevant findings related to GBM metabolism and cell death and how these observations are influencing the field. We will provide current approaches that are applied in the field to measure metabolomic changes in GBM models, including the detection of unlabeled and labeled metabolites as well as extracellular flux analysis.
... These results suggest a relation between Usp9X and ER stress in the context of MPNST. Additionally, an overexpression of Noxa, a pro-apoptotic factor regulated by ATF3 and ATF4 and preceded the Mcl-1down-regulation [98][99][100]. Noxa hyperactivation facilitates the release of BAK and BIM and triggers BAX/BAK mediated apoptosis. ...
Malignant peripheral nerve sheath tumors (MPNST) are rare but one of the most aggressive types of cancer. Currently, there are no effective chemotherapy strategies for these malignancies. The inactivation of the neurofibromatosis type I (NF1) gene, followed by loss of TP53, is an early stage in MPNST carcinogenesis. NF1 is a negative regulator of the Ras proteins family, which are key factors in regulating cell growth, homeostasis and survival. Cell cycle dysregulation induces a stress phenotype, such as proteotoxic stress, metabolic stress, and oxidative stress, which should result in cell death. However, in the case of neoplastic cells, we observe not only the avoidance of apoptosis, but also the impact of stress factors on the treatment effectiveness. This review focuses on the pathomechanisms underlying MPNST cells physiology, and discusses the possible ways to develop a successful treatment based on the molecular background of the disease.
... The BCL2 inhibitor approved by the regulatory agency is Obatoclax, whose indications are narrow and mainly targeted at patients with recurrent chronic lymphocytic lymphoma/leukemia [17][18][19]. In most common B-cell malignancies, existing BCL2 inhibitors show only moderate clinical activity [20]. Therefore, we need more effective BCL2 targeted drugs. ...
Ideal lead compounds and candidate drugs with inhibitory effect on BCL2 were screened from ZINC database, which laid a foundation for drug development and compound improvement of drug treatment for diffuse large B-cell lymphoma (DLCBL). Identification of potential BCL2 inhibitors by computer-aided virtual screening. Libdock was applied to 17,931 compounds and the top 20 were selected for further analysis. Selected compounds were performed absorption, distribution, metabolism, and excretion (ADME) and toxicity prediction. The binding affinity between the selected ligands and BCL2 was confirmed by Molecular docking. The new natural compounds, ZINC00000255131 and ZINC00013298233, were found to bind closely with BCL2. Furthermore, they all scored lower in ames-induced mutagenicity, rodent carcinogenicity, non-developmental toxicity potential, and cytochrome P4502D6 tolerance. Molecular dynamics simulation shows that the combinations of ZINC00000255131 and ZINC00013298233 with BCL2 in the natural environment are more stable. Two new compounds, ZINC00000255131 and ZINC00013298233, were found to be potential inhibitors of BCL2. These compounds have been proved to be safe, which is of great significance for the development and improvement of DLCBL drugs.
... Treatment with vorinostat (HDAC inhibitor) and tranylcypromine (histone lysine demethylase KDM1A inhibitor) ( Figure 2) decreased GBM stem cell proliferation and led to significant tumor regression in mouse models [166]. Also, the use of bromodomain inhibitors have risen in popularity, due to enhanced tumor lethality [167]. In fact, the BET inhibitor caused downregulation of the lncRNA HOTAIR, which induced cell cycle arrest in GBM cells [168]. ...
Highly aggressive tumors are characterized by a highly invasive phenotype, and they display chemoresistance. Furthermore, some of the tumors lack expression of biomarkers for target therapies. This is the case of small-cell lung cancer, triple-negative breast cancer, pancreatic ductal adenocarcinoma, glioblastoma, metastatic melanoma, and advanced ovarian cancer. Unfortunately, these patients show a low survival rate and most of the available drugs are ineffective. In this context, epigenetic modifications have emerged to provide the causes and potential treatments for such types of tumors. Methylation and hydroxymethylation of DNA, and histone modifications, are the most common targets of epigenetic therapy, to influence gene expression without altering the DNA sequence. These modifications could impact both oncogenes and tumor suppressor factors, which influence several molecular pathways such as epithelial-to-mesenchymal transition, WNT/β–catenin, PI3K–mTOR, MAPK, or mismatch repair machinery. However, epigenetic changes are inducible and reversible events that could be influenced by some environmental conditions, such as UV exposure, smoking habit, or diet. Changes in DNA methylation status and/or histone modification, such as acetylation, methylation or phosphorylation, among others, are the most important targets for epigenetic cancer therapy. Therefore, the present review aims to compile the basic information of epigenetic modifications, pathways and factors, and provide a rationale for the research and treatment of highly aggressive tumors with epigenetic drugs.
... Indeed, a wide range of BETi have now been tested together with various BH3-mimetics, though most studies have focussed on Venetoclax where enhanced responses from combining the drugs have been seen in vitro and in vivo in many haematological malignancies including T cell lymphoma, CLL, T cell acute lymphoblastic leukaemia, and diffuse large B cell lymphoma [289][290][291][292][293][294][295][296][297], and some solid tumours such as small cell lung cancer [298]. The dual BCL-XL/BCL-2 inhibitor Navitoclax was also shown to synergise with BETi in small cell lung cancer, colorectal cancer, glioma and B-cell lymphomas [299][300][301][302], whilst BH3-mimetics targeting MCL-1 enhance BETi activity in AML and melanoma [292,303]. ...
B-Cell Lymphoma 2 (BCL-2), c-MYC and related proteins are arguably amongst the most widely studied in all of biology. Every year there are thousands of papers reporting on different aspects of their biochemistry, cellular and physiological mechanisms and functions. This plethora of literature can be attributed to both proteins playing essential roles in the normal functioning of a cell, and by extension a whole organism, but also due to their central role in disease, most notably, cancer. Many cancers arise due to genetic lesions resulting in deregulation of both proteins, and indeed the development and survival of tumours is often dependent on co-operativity between these protein families. In this review we will discuss the individual roles of both proteins in cancer, describe cancers where co-operativity between them has been well-characterised and finally, some strategies to target these proteins therapeutically.
... The BCL2 inhibitor approved by the regulatory agency is Venetoclax, whose indications are narrow and mainly targeted at patients with recurrent chronic lymphocytic lymphoma/leukemia [17][18][19] . In most common B-cell malignancies, existing BCL2 inhibitors show only moderate clinical activity [20] . Therefore, we need more effective BCL2 targeted drugs. ...
Object: Ideal lead compounds and candidate drugs with inhibitory effect on BCL2 were screened from ZINC database, which laid a foundation for drug development and compound improvement of drug treatment for diffuse large B-cell lymphoma (DLCBL).
Methods: Identification of potential BCL2 inhibitors by computer-aided virtual screening. Libdock was applied to value 17931 compounds and top20 were selected for further analysis. Selected compounds were performed absorption, distribution, metabolism, and excretion (ADME) and toxicity prediction. The binding affinity between the selected ligands and BCL2 was confirmed by Molecular docking.
Results: The new natural compounds ZINC00000255131 and ZINC00013298233 were found to bind closely with BCL2. Furthermore, they all scored lower in ames-induced mutagenicity, rodent carcinogenicity, non-developmental toxicity potential, and cytochrome P4502D6 tolerance. Molecular dynamics simulation shows that the combinations of ZINC00000255131 and ZINC00013298233 with BCL2 in the natural environment are more stable.
Conclusion: Two new compounds ZINC00000255131 and ZINC00013298233 were found to be potential inhibitors of BCL2. These compounds have been proved to be safe, which is of great significance for the development and improvement of DLCBL drugs.
... Given the limited cell death induction by THZ1, we asked whether the killing efficacy of this compound might be enhanced in the presence of BH3-mimetics, such as ABT263. This hypothesis largely emerged from the fact that THZ1 suppressed Mcl-1 protein levels and that drugs that lower Mcl-1 levels have commonly been associated to enhance the efficacy of BH3-mimetics that target either Bcl-2, Bcl-xL, or both [7,9,[42][43][44][45][46]. Consistently, we found that THZ1 and BH3-mimetics synergistically reduced the viability of GBM cells across a broad range of different model systems of human GBM. ...
... A limitation of the current work is that our studies did not include orthotopic in vivo studies, given that the microenvironment and the blood brain barrier might interfere with the efficacy of the treatment. These results are in keeping with earlier drug combinations involving BH3-mimetics [7,9,[42][43][44][45][46]. ...
Apoptotic resistance remains a hallmark of glioblastoma (GBM), the most common primary brain tumor in adults, and a better understanding of this process may result in more efficient treatments. By utilizing chromatin immunoprecipitation with next-generation sequencing (CHIP-seq), we discovered that GBMs harbor a super enhancer around the Mcl-1 locus, a gene that has been known to confer cell death resistance in GBM. We utilized THZ1, a known super-enhancer blocker, and BH3-mimetics, including ABT263, WEHI-539, and ABT199. Combined treatment with BH3-mimetics and THZ1 led to synergistic growth reduction in GBM models. Reduction in cellular viability was accompanied by significant cell death induction with features of apoptosis, including disruption of mitochondrial membrane potential followed by activation of caspases. Mechanistically, THZ1 elicited a profound disruption of the Mcl-1 enhancer region, leading to a sustained suppression of Mcl-1 transcript and protein levels, respectively. Mechanism experiments suggest involvement of Mcl-1 in the cell death elicited by the combination treatment. Finally, the combination treatment of ABT263 and THZ1 resulted in enhanced growth reduction of tumors without induction of detectable toxicity in two patient-derived xenograft models of GBM in vivo. Taken together, these findings suggest that combined epigenetic targeting of Mcl-1 along with Bcl-2/Bcl-xL is potentially therapeutically feasible.
