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(A) Sections prepared from paraffin-embedded bone marrow (iliac crest) of patients with polycythemia vera (PV; patient #06), essential thrombocythemia (ET; patient #34) or primary myelofibrosis (PMF; patient #29) were stained with an anti-phosphorylated signal transducer and activator of transcription-5 (pSTAT5) antibody using immunohistochemistry. Examples of nuclear- and cytoplasmic staining are shown in Figure A1. Scale bar: 30 µm. Patient characteristics are shown in Table A1. (B,C) Bone marrow (BM) mononuclear cells (MNC) of patients with PV (patient #30), ET (patient #08) or PMF (patient #29) were stained with an anti-pSTAT5 Alexa-647 antibody. Intracellular expression levels of pSTAT5 were analyzed by flow cytometry in total MNC (B), or in cell subsets gated for CD34, CD14 or CD15 (C). The isotype-matched control antibody is also shown (open black histogram). Numbers in the small boxes represent the staining index defined as the ratio of the median fluorescence intensity (MFI) obtained with the anti-pSTAT5 antibody and MFI obtained with the isotype-matched control antibody (mIgG1).
Source publication
Janus kinase 2 (JAK2) and signal transducer and activator of transcription-5 (STAT5) play a key role in the pathogenesis of myeloproliferative neoplasms (MPN). In most patients, JAK2 V617F or CALR mutations are found and lead to activation of various downstream signaling cascades and molecules, including STAT5. We examined the presence and distribu...
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Background
The meta-analysis compared the efficacy and safety of momelotinib, ruxolitinib and pacitinib in patients with myeloproliferative neoplasms(MPN), which includes essential thrombocythemia, polycythemia vera and primary myelofibrosis.
Methods
We searched multiple databases and collected relevant studies before Dec. 20,2019. According to pr...
Citations
... Several small-molecule SH2 domain inhibitors have been identi-fied for STAT5. Of these, AC-4-130 was able to decrease STAT5 activation and transcription, as well as proliferation and clonogenic growth in AML cell lines and MPN stem cells [87,88]. Similarly, the compound 17f was also able to inhibit phosphorylation of STAT5 (but not STAT3) and growth in both CML and AML cell lines [89], while ISST5-002 prevented STAT5 phosphorylation and dimerization in response to JAK2 V617F and BCR-ABL1 [90]. ...
Simple Summary
A group of blood diseases called myeloproliferative neoplasms (MPNs) cause a buildup of certain blood cell types in affected individuals. Each MPN category has a distinct clinical presentation and is associated with mutations in specific genes. However, these various categories all chronically switch on the same cellular pathway, involving signal transducer and activator of transcription (STAT) proteins. This perspective provides new insight for understanding and managing these important diseases.
Abstract
Myeloproliferative neoplasms (MPNs) are hematopoietic diseases characterized by the clonal expansion of single or multiple lineages of differentiated myeloid cells that accumulate in the blood and bone marrow. MPNs are grouped into distinct categories based on key clinical presentations and distinctive mutational hallmarks. These include chronic myeloid leukemia (CML), which is strongly associated with the signature BCR::ABL1 gene translocation, polycythemia vera (PV), essential thrombocythemia (ET), and primary (idiopathic) myelofibrosis (PMF), typically accompanied by molecular alterations in the JAK2, MPL, or CALR genes. There are also rarer forms such as chronic neutrophilic leukemia (CNL), which involves mutations in the CSF3R gene. However, rather than focusing on the differences between these alternate disease categories, this review aims to present a unifying molecular etiology in which these overlapping diseases are best understood as disruptions of normal hematopoietic signaling: specifically, the chronic activation of signaling pathways, particularly involving signal transducer and activator of transcription (STAT) transcription factors, most notably STAT5B, leading to the sustained stimulation of myelopoiesis, which underpins the various disease sequalae.
... AC-4-130 significantly suppressed AML cells both in vitro and in vivo, demonstrating the relevance of targeting STAT5 [229]. Several recent studies have further evaluated AC-4-130 in lymphoma and AML, characterizing the role of STAT5 in maintenance of stemness, PDGFRβ-mediated oncogenic signaling, and FLT3 or TET2 mutated leukemias [230][231][232]. For example, Hadzijusufovic et al. determined that CD34+/CD38− myeloproliferative neoplastic (MPN) stem cells express high levels of phosphorylated STAT5 [232]. ...
... Several recent studies have further evaluated AC-4-130 in lymphoma and AML, characterizing the role of STAT5 in maintenance of stemness, PDGFRβ-mediated oncogenic signaling, and FLT3 or TET2 mutated leukemias [230][231][232]. For example, Hadzijusufovic et al. determined that CD34+/CD38− myeloproliferative neoplastic (MPN) stem cells express high levels of phosphorylated STAT5 [232]. Treatment with AC-4-130-attenuated cell growth suggested that STAT5 played a critical role in MPN cell proliferation [232]. ...
... For example, Hadzijusufovic et al. determined that CD34+/CD38− myeloproliferative neoplastic (MPN) stem cells express high levels of phosphorylated STAT5 [232]. Treatment with AC-4-130-attenuated cell growth suggested that STAT5 played a critical role in MPN cell proliferation [232]. Seipel et al. investigated whether STAT5 inhibition could enhance the efficacy of FLT3 inhibitors to treat FLT3-mutated AML [211]. ...
Ovarian cancer (OvCa) is a deadly gynecologic malignancy that presents many clinical challenges due to late-stage diagnoses and the development of acquired resistance to standard-of-care treatment protocols. There is an increasing body of evidence suggesting that STATs may play a critical role in OvCa progression, resistance, and disease recurrence, and thus we sought to compile a comprehensive review to summarize the current state of knowledge on the topic. We have examined peer reviewed literature to delineate the role of STATs in both cancer cells and cells within the tumor microenvironment. In addition to summarizing the current knowledge of STAT biology in OvCa, we have also examined the capacity of small molecule inhibitor development to target specific STATs and progress toward clinical applications. From our research, the best studied and targeted factors are STAT3 and STAT5, which has resulted in the development of several inhibitors that are under current evaluation in clinical trials. There remain gaps in understanding the role of STAT1, STAT2, STAT4, and STAT6, due to limited reports in the current literature; as such, further studies to establish their implications in OvCa are necessitated. Moreover, due to the deficiency in our understanding of these STATs, selective inhibitors also remain elusive, and therefore present opportunities for discovery.
... A number of previous and more recent data suggest that immature myeloid cells in MPN display CD34. [41][42][43][44][45][46][47] However, only a few attempts have been made to confirm functional stemness of these cells in a xenotransplantation model. A related problem is that it is notoriously difficult to engraft MPN cells in NSG mice. ...
... 44 We have recently shown that putative CD34 + /CD38 À MPN stem cells express pSTAT5. 46 However, little is known about phenotypes and target expression profiles of NSC in ET, PV, and PMF. ...
... Phenotyping of CD34 + /CD38 À stem cells and CD34 + /CD38 + progenitor cells in BM and PB samples was performed by multicolor flow cytometry using combinations of fluorochrome-conjugated mAb (Table S1) essentially as described. 34,35,46,50 The gating strategy employed to identify NSC (MPN) or LSC (sAML) is shown in Figure S1. Antibody-staining results were controlled by isotype-matched control mAb and were expressed as staining index (SI) defined as ratio of the median fluorescence intensities (MFI) obtained with CD-specific mAb and isotypematched control mAb (MFI mAb divided by MFI control mAb) as reported. ...
Myeloproliferative neoplasms (MPN) are characterized by uncontrolled expansion of myeloid cells, disease‐related mutations in certain driver‐genes including JAK2, CALR, and MPL, and a substantial risk to progress to secondary acute myeloid leukemia (sAML). Although behaving as stem cell neoplasms, little is known about disease‐initiating stem cells in MPN. We established the phenotype of putative CD34⁺/CD38⁻ stem cells and CD34⁺/CD38⁺ progenitor cells in MPN. A total of 111 patients with MPN suffering from polycythemia vera, essential thrombocythemia, or primary myelofibrosis (PMF) were examined. In almost all patients tested, CD34⁺/CD38⁻ stem cells expressed CD33, CD44, CD47, CD52, CD97, CD99, CD105, CD117, CD123, CD133, CD184, CD243, and CD274 (PD‐L1). In patients with PMF, MPN stem cells often expressed CD25 and sometimes also CD26 in an aberrant manner. MPN stem cells did not exhibit substantial amounts of CD90, CD273 (PD‐L2), CD279 (PD‐1), CD366 (TIM‐3), CD371 (CLL‐1), or IL‐1RAP. The phenotype of CD34⁺/CD38⁻ stem cells did not change profoundly during progression to sAML. The disease‐initiating capacity of putative MPN stem cells was confirmed in NSGS mice. Whereas CD34⁺/CD38⁻ MPN cells engrafted in NSGS mice, no substantial engraftment was produced by CD34⁺/CD38⁺ or CD34⁻ cells. The JAK2‐targeting drug fedratinib and the BRD4 degrader dBET6 induced apoptosis and suppressed proliferation in MPN stem cells. Together, MPN stem cells display a unique phenotype, including cytokine receptors, immune checkpoint molecules, and other clinically relevant target antigens. Phenotypic characterization of neoplastic stem cells in MPN and sAML should facilitate their enrichment and the development of stem cell‐eradicating (curative) therapies.
... This evidence supports our hypothesis that low immunogenicity and chemotherapy resistance may be one of the reasons for the recurrence of CD34 + CD38 − leukemia cells [9]. Others have reported that STAT5 expressed in CD34 + CD38 − stem cells is a potential molecular target for Ph-negative myeloproliferative tumors [22]. Comparing the relative proportions of standard-risk, median-risk, and high-risk patients between the two groups, we found no significant differences. ...
Objective
Acute lymphoblastic leukemia is the most common malignant disease in children. CD34 and CD38 are expressed in both normal and leukemia cells, but studies of their prognostic associations in childhood acute lymphoblastic leukemia are limited. The aim of this study was to investigate the prognostic effect of CD34 + CD38⁻ leukemia cells in this childhood cancer.
Methods
From January 2014 to January 2019, children with newly diagnosed acute lymphoblastic leukemia were included in this study and followed up until July 2020. The participants were divided into CD34⁺ and CD34⁻ groups according to CD34 expression level at diagnosis, and the CD34⁺ group was further divided into CD34 + CD38⁻ and CD34 + CD38⁺ subgroups based on CD38 expression level. We tracked clinical biological features, therapeutic outcomes, and other patient data for comparisons.
Results
The OS and EFS did not differ significantly between the CD34⁺ and CD34⁻ groups (both P > 0.05). CD34⁺CD38⁻ group and CD34⁺CD38⁺ group were further compared. OS differed significantly between these two groups (χ2 = 3.89, P = 0.048), as did the recurrence rate (χ2 = 5.04, P = 0.025), but EFS did not (χ2 = 1.45, P > 0.05). Survival analysis in patients with recurrence showed a significantly higher OS for the CD34 + CD38⁺ group compared with the CD34 + CD38⁻ group (χ2 = 5.08, P = 0.024). The CD34⁺CD38⁻ group and CD34⁺CD38⁺ group were matched for propensity scores. When recurrence was compared in the two groups after matching, the difference was statistically significant (P < 0.001).
Conclusion
CD34⁺ and CD34⁻ expression does not differ by prognosis in children with acute lymphoblastic leukemia, but CD34 + CD38⁻ may indicate a poor prognosis.
... The molecular basis of the increase in cytokine receptor expression remains unknown. Since CD25 is a STAT5-target gene in LSC [46,47] and Phenotypic characterization of leukemia-initiating stem cells in chronic myelomonocytic leukemia STAT5 is a well-known driver in AML [48,49], an attractive hypothesis would be that oncogenic signaling through STAT5 promotes the expression of CD25 in post-CMML sAML LSC. ...
Chronic myelomonocytic leukemia (CMML) is a stem cell-derived neoplasm characterized by dysplasia, uncontrolled expansion of monocytes, and substantial risk to transform to secondary acute myeloid leukemia (sAML). So far, little is known about CMML-initiating cells. We found that leukemic stem cells (LSC) in CMML reside in a CD34⁺/CD38⁻ fraction of the malignant clone. Whereas CD34⁺/CD38⁻ cells engrafted NSGS mice with overt CMML, no CMML was produced by CD34⁺/CD38⁺ progenitors or the bulk of CD34⁻ monocytes. CMML LSC invariably expressed CD33, CD117, CD123 and CD133. In a subset of patients, CMML LSC also displayed CD52, IL-1RAP and/or CLL-1. CMML LSC did not express CD25 or CD26. However, in sAML following CMML, the LSC also expressed CD25 and high levels of CD114, CD123 and IL-1RAP. No correlations between LSC phenotypes, CMML-variant, mutation-profiles, or clinical course were identified. Pre-incubation of CMML LSC with gemtuzumab-ozogamicin or venetoclax resulted in decreased growth and impaired engraftment in NSGS mice. Together, CMML LSC are CD34⁺/CD38⁻ cells that express a distinct profile of surface markers and target-antigens. During progression to sAML, LSC acquire or upregulate certain cytokine receptors, including CD25, CD114 and CD123. Characterization of CMML LSC should facilitate their enrichment and the development of LSC-eradicating therapies.
... Nevertheless, STAT5 was reported to be crucial for leukemia initiation and maintenance in vitro and in vivo. Its increased expression and persistent activation in CSCs was observed in case of CML and solid tumors [17]. Thus, the design of drugs that target STAT5 and/or CSCs might result in significant improvement regarding the therapy and treatment-free remission of CML patients. ...
... The aim of the present study was to evaluate the activation status of the JAK2/STAT5 signaling pathway in bromocriptine-resistant prolactinoma tissues and to assess the potential chemotherapeutic sensitizing effect of pimozide on the bromocriptine-resistant prolactinoma cells. As tumor stem cells serve a vital role in tumor recurrence, metastasis and drug resistance (16,18,19), the effect of pimozide on prolactinoma cell stemness was also assessed.collectively, these experiments provide a rationale for further clinical studies on the use of pimozide as a chemosensitizer in bromocriptine-resistant prolactinomas. ...
As hyperprolactinemia is observed in patients with bromocriptine-resistant prolactinoma, prolactin (PRL) has been implicated in the development of bromocriptine resistance. Since PRL primarily mediates cell survival and drug resistance via the Janus kinase-2 (JAK2)/signal transducer and activator of transcription 5A (STAT5) signaling pathway, the STAT5 inhibitor, pimozide, may inhibit cell proliferation and reverse bromocriptine resistance in prolactinoma cells. In the present study, compared with bromocriptine or pimozide alone, the combination of pimozide and bromocriptine exerted enhanced reduction in cell growth and proliferation, and increased apoptosis and cell cycle arrest in bromocriptine-resistant prolactinoma cells. A reduction in phospho-STAT5, cyclin D1 and B-cell lymphoma extra-large (Bcl-xL) expression levels were observed in cells treated with the combination of drugs. In addition, pimozide suppressed spheroid formation of human pituitary adenoma stem-like cells, and reduced the protein expression of the cancer stem cell markers, CD 133 and nestin. Pimozide did not exert any additional antitumor activity in STAT5-knockdown primary culture cells of human bromocriptine-resistant prolactinomas. Furthermore, Pimozide combined with bromocriptine treatment significantly reduced human prolactinoma xenograft growth. Western blot and immunohistochemical analyses also demonstrated significant inhibition of cell proliferation and stem cell marker proteins in vivo. Collectively, these data indicated that pimozide treatment reduced prolactinoma growth by targeting both proliferating cells and stem cells, at least in part, by inhibiting the STAT5/Bcl-xL and STAT5/cyclin D1 signaling pathways. © This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License.
... Additional studies have explored the role of STATs in hematological malignancies. Phospho-STAT5 was shown to play a key role in CD34+/CD38− myeloproliferative neoplasms with downregulation by pharmacologic inhibition of JAK and STAT [24]. JAK/STAT mutations were also identified in patients with the rare and aggressive T-cell prolymphocytic leukemia (T-PLL), pointing towards a possible mode of transformation [25]. ...
Insights into the mutational landscape of the human cancer genome coding regions defined about 140 distinct cancer driver genes in 2013, which approximately doubled to 300 in 2018 following advances in systems cancer biology studies [...]
The dysregulation of the Janus family tyrosine kinase‐signal transducer and activator of transcription (JAK‐STAT) is closely related to acute lymphoblastic leukaemia (ALL), whereas the clinical value of phosphorylated STAT5 (pSTAT5) remains elusive. Herein we performed a prospective study on clinical significance of flow cytometry‐based pSTAT5 in adult B‐ALL patients. A total of 184 patients were enrolled in the Precision‐Classification‐Directed‐Target‐Total‐Therapy (PDT)‐ALL‐2016 cohort between January 2018 and December 2021, and STAT5 phosphorylation was detected by flow cytometry at diagnosis. Based on flow‐pSTAT5, the population was classified into pSTAT5 low (113/184, 61.1%) and pSTAT5 high (71/184, 38.9%). Overall survival (OS) and event‐free survival (EFS) were inferior in pSTAT5 high patients than in those with pSTAT5 low (OS, 44.8% vs. 65.2%, p = 0.004; EFS, 23.5% vs. 52.1%, p < 0.001), which was further confirmed in an external validation cohort. Furthermore, pSTAT5 plus flow‐based minimal residual disease (MRD) postinduction defines a novel risk classification as being high risk (HR, pSTAT5 high + MRD+), standard risk (SR, pSTAT5 low + MRD−) and others as moderate‐risk group. Three identified patient subgroups are distinguishable with disparate survival curves (3‐year OS rates, 36.5%, 56.7% and 76.3%, p < 0.001), which was confirmed on multivariate analysis (hazard ratio 3.53, p = 0.003). Collectively, our study proposed a novel, simple and flow‐based risk classification by integrating pSTAT5 and MRD in favour of risk‐guided treatment for B‐ALL.
Conventional therapy for myeloproliferative neoplasm (MPN) has modest disease-modifying effect. In this chapter, we discuss the emerging novel agents and approaches that may potentially modify the underlying disease biology in MPN.
