STAT5A

Gene Summary

Gene:STAT5A; signal transducer and activator of transcription 5A
Aliases: MGF, STAT5
Location:17q21.2
Summary:The protein encoded by this gene is a member of the STAT family of transcription factors. In response to cytokines and growth factors, STAT family members are phosphorylated by the receptor associated kinases, and then form homo- or heterodimers that translocate to the cell nucleus where they act as transcription activators. This protein is activated by, and mediates the responses of many cell ligands, such as IL2, IL3, IL7 GM-CSF, erythropoietin, thrombopoietin, and different growth hormones. Activation of this protein in myeloma and lymphoma associated with a TEL/JAK2 gene fusion is independent of cell stimulus and has been shown to be essential for tumorigenesis. The mouse counterpart of this gene is found to induce the expression of BCL2L1/BCL-X(L), which suggests the antiapoptotic function of this gene in cells. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Dec 2013]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:signal transducer and activator of transcription 5A
Source:NCBIAccessed: 11 March, 2017

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Prolactin
  • Trans-Activators
  • Cell Proliferation
  • Gene Expression Profiling
  • Single Nucleotide Polymorphism
  • Cancer Gene Expression Regulation
  • Breast Cancer
  • Chromosome 17
  • siRNA
  • STAT5 Transcription Factor
  • Immunohistochemistry
  • Transcription Factor AP-1
  • STAT3 Transcription Factor
  • Cell Survival
  • Promoter Regions
  • p53 Protein
  • Phosphorylation
  • Mutation
  • RNA Interference
  • Milk Proteins
  • RTPCR
  • Prostate Cancer
  • Transcription
  • Cultured Cells
  • Chronic Myelogenous Leukemia
  • Base Sequence
  • Apoptosis
  • Disease Progression
  • STAT Transcription Factors
  • Biomarkers, Tumor
  • DNA-Binding Proteins
  • Tyrphostins
  • Messenger RNA
  • Molecular Sequence Data
  • Neoplastic Cell Transformation
  • Skin Cancer
  • Signal Transduction
  • Xenograft Models
  • JAK2
  • Western Blotting
Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: STAT5A (cancer-related)

Farhadi E, Zaker F, Safa M, Rezvani MR
miR-101 sensitizes K562 cell line to imatinib through Jak2 downregulation and inhibition of NF-κB target genes.
Tumour Biol. 2016; 37(10):14117-14128 [PubMed] Related Publications
Imatinib mesylate (IM) is a frontline treatment in the early chronic phase of chronic myeloid leukemia (CML). However, intrinsic and acquired resistance against this drug has been defined and this issue has become a problem and a challenge in CML treatment. According to new findings, the inhibition of Janus kinase 2 (Jak2) in Bcr-Abl+ cells can promote apoptosis in IM-resistant cells. microRNAs (miRNAs) regulate the gene expression by targeting the messenger RNA (mRNA) for degradation. Recently, a growing body of evidence has implicated that dysregulation of miRNAs is associated with cancer initiation and development. In this report, we proposed that miRNA-101 targets Jak2 mRNA and regulates its expression and induces K562 leukemia cell apoptosis. Here, we transduced the K562 cell line with a miR-101-overexpressing vector and evaluated the Jak2 mRNA level. Our results showed that miR-101 overexpression in Bcr-Abl+ cells reduced the Jak2 mRNA level. Moreover, imatinib treatment and miR-101 upregulation led to miR-23a overexpression, which has putative binding site(s) on 3'-untranslated regions (3'-UTRs) of STAT5, CCND1, and Bcl-2 genes. Our results also indicated that miR-101 overexpression inhibited cell proliferation indicated by the MTT assay and promoted apoptosis detected via flow cytometry. Importantly, mRNA expression of NF-kappa B-regulated anti-apoptotic (Bcl-2, Bcl-xl, MCL-1, XIAP, and survivin) and proliferative (c-Myc and CCND1) genes was decreased. These findings suggest that miR-101 acts as a tumor suppressor by downregulating Jak2 expression and sensitizing K562 cells to imatinib. Therefore, restoration of miR-101 may be a therapeutic approach for CML treatment.

Robens BK, Gembé E, Fassunke J, et al.
Abundance of LRP12 C-rs9694676 allelic promoter variant in epilepsy-associated gangliogliomas.
Life Sci. 2016; 155:70-5 [PubMed] Related Publications
AIMS: Chronic epilepsy associated gangliogliomas (GGs) represent tumors composed of irregularly distributed, often dysmorphic, neurons and neoplastic astroglia. The pathogenesis of GGs is largely unknown. Low-density lipoprotein receptor-related protein 12 (LRP12) is critical for brain development and involved in tumorigenesis of non-cerebral neoplasms.
MAIN METHODS: Here, we have examined a potential role of LRP12 in the pathogenesis of GGs by a combination of mRNA quantification and molecular-biological in vitro assays.
KEY FINDINGS: We observed a significant increase of the single nucleotide polymorphism (SNP) rs9694676 C-allele, located in the LRP12 promoter, in GGs compared to normal control individuals. C-allele expression is correlated with abundant seizure frequency. Expression of LRP12 was lower in GGs than in control brain. In luciferase assays, the C-allele of rs9694676 decreases both, the basal LRP12 core promoter activity and the stimulatory effect of the transcription factor (TF) STAT5a.
SIGNIFICANCE: Accumulation of functional promoter-associated allelic variants with impact on the transcriptional regulation of LRP12 provides a new pathomechanism for GGs, i.e. highly differentiated epileptogenic brain tumors.

Lim SL, Mustapha NM, Goh YM, et al.
Metastasized lung cancer suppression by Morinda citrifolia (Noni) leaf compared to Erlotinib via anti-inflammatory, endogenous antioxidant responses and apoptotic gene activation.
Mol Cell Biochem. 2016; 416(1-2):85-97 [PubMed] Related Publications
Metastasized lung and liver cancers cause over 2 million deaths annually, and are amongst the top killer cancers worldwide. Morinda citrifolia (Noni) leaves are traditionally consumed as vegetables in the tropics. The macro and micro effects of M. citrifolia (Noni) leaves on metastasized lung cancer development in vitro and in vivo were compared with the FDA-approved anti-cancer drug Erlotinib. The extract inhibited the proliferation and induced apoptosis in A549 cells (IC50 = 23.47 μg/mL) and mouse Lewis (LL2) lung carcinoma cells (IC50 = 5.50 μg/mL) in vitro, arrested cancer cell cycle at G0/G1 phases and significantly increased caspase-3/-8 without changing caspase-9 levels. The extract showed no toxicity on normal MRC5 lung cells. Non-small-cell lung cancer (NSCLC) A549-induced BALB/c mice were fed with 150 and 300 mg/kg M. citrifolia leaf extract and compared with Erlotinib (50 mg/kg body weight) for 21 days. It significantly increased the pro-apoptotic TRP53 genes, downregulated the pro-tumourigenesis genes (BIRC5, JAK2/STAT3/STAT5A) in the mice tumours, significantly increased the anti-inflammatory IL4, IL10 and NR3C1 expression in the metastasized lung and hepatic cancer tissues and enhanced the NFE2L2-dependent antioxidant responses against oxidative injuries. The extract elevated serum neutrophils and reduced the red blood cells, haemoglobin, corpuscular volume and cell haemoglobin concentration in the lung cancer-induced mammal. It suppressed inflammation and oedema, and upregulated the endogenous antioxidant responses and apoptotic genes to suppress the cancer. The 300 mg/kg extract was more effective than the 50 mg/kg Erlotinib for most of the parameters measured.

Yu Y, Luo Y, Zheng Y, et al.
Exploring the mechanism of non-small-cell lung cancer cell lines resistant to epidermal growth factor receptor tyrosine kinase inhibitor.
J Cancer Res Ther. 2016 Jan-Mar; 12(1):121-5 [PubMed] Related Publications
PURPOSE: Here we aimed to explore the possible mechanism and potential regulatory relationships in which the non.small.cell lung cancer. (NSCLC)-resisted epidermal growth factor receptor. (EGFR) tyrosine kinase inhibitor erlotinib.
MATERIALS AND METHODS: GSE38310, the gene expression profiles of NSCLC cell lines treated with dimethylsulfoxide or erlotinib, including HCC827, ER3, and T15-2, were downloaded from Gene Expression Omnibus database and preprocessed by normalization. Basing on the regulatory relationships of transcriptional factors obtained from University of California Santa Cruz. (UCSC) database, the differentially expressed genes. (DEGs) were screened using limma package in R with. |logFC| >1 and P < 0.05, and regulatory networks of these DEGs were built with supervised inference of regulatory networks (SIRENE). Subsequently, differentially regulatory networks were compared basing on Limit Fold Change. (LFC) method.
RESULTS: Totally 24,380 genes were obtained, 1,531 DEGs were identified in HCC827 cell lines, 37 DEGs in ER3 cell lines, 156 DEGs in T15-2 cell lines. After removing the redundancy genes, 1,575 differentially expressed genes were got at last. Basing on three regulatory networks of HCC827 cell lines, ER3 cell lines and T15-2 cell lies, sex-determining region Y (SRY).related high mobility group-box gene 9. (SOX9) and Suppressor of cytokine signaling 3 (STAT3) were identified by comparing with HCC827 and ER3 networks. And suppressor of cytokine signaling 5 B (STAT5B), early growth response-1 (EGR1) and STAT6 were obtained in comparison of HCC827 and T15-2 networks.
CONCLUSIONS: The regulatory edges with remarkable changes between HCC827 and ER3, HCC827 and T15.2 included some transcription factors and genes. (e. g., STAT3 and SOX9). STAT3, SOX9, STAT5B, EGR1, and STAT6 might affect the resistance of NSCLC to erlotinib.

Lu JW, Wang AN, Liao HA, et al.
Cabozantinib is selectively cytotoxic in acute myeloid leukemia cells with FLT3-internal tandem duplication (FLT3-ITD).
Cancer Lett. 2016; 376(2):218-25 [PubMed] Related Publications
Cabozantinib is an oral multikinase inhibitor that exhibits anti-tumor activity in several cancers. We found that cabozantinib was significantly cytotoxic to MV4-11 and Molm-13 cells that harbored FLT3-ITD, resulting in IC50 values of 2.4 nM and 2.0 nM, respectively. However, K562, OCI-AML3 and THP-1 (leukemia cell lines lacking FLT3-ITD) were resistant to cabozantinib, showing IC50 values in the micromolar range. Cabozantinib arrested MV4-11 cell growth at the G0/G1 phase within 24 h, which was associated with decreased phosphorylation of FLT3, STAT5, AKT and ERK. Additionally, cabozantinib induced MV4-11 cell apoptosis in a dose-dependent manner (as indicated by annexin V staining and high levels of cleaved caspase 3 and PARP-1), down-regulated the anti-apoptotic protein survivin and up-regulated the pro-apoptotic protein Bak. Thus, cabozantinib is selectively cytotoxic to leukemia cells with FLT3-ITD, causing cell-cycle arrest and apoptosis. In mouse xenograft model, cabozantinib significantly inhibited MV4-11 and Molm-13 tumor growth at a dosage of 10 mg/kg and showed longer survival rate. Clinical trials evaluating the efficacy of cabozantinib in acute myeloid leukemia (AML) with FLT3-ITD are warranted.

Sontakke P, Koczula KM, Jaques J, et al.
Hypoxia-Like Signatures Induced by BCR-ABL Potentially Alter the Glutamine Uptake for Maintaining Oxidative Phosphorylation.
PLoS One. 2016; 11(4):e0153226 [PubMed] Free Access to Full Article Related Publications
The Warburg effect is probably the most prominent metabolic feature of cancer cells, although little is known about the underlying mechanisms and consequences. Here, we set out to study these features in detail in a number of leukemia backgrounds. The transcriptomes of human CB CD34+ cells transduced with various oncogenes, including BCR-ABL, MLL-AF9, FLT3-ITD, NUP98-HOXA9, STAT5A and KRASG12V were analyzed in detail. Our data indicate that in particular BCR-ABL, KRASG12V and STAT5 could impose hypoxic signaling under normoxic conditions. This coincided with an upregulation of glucose importers SLC2A1/3, hexokinases and HIF1 and 2. NMR-based metabolic profiling was performed in CB CD34+ cells transduced with BCR-ABL versus controls, both cultured under normoxia and hypoxia. Lactate and pyruvate levels were increased in BCR-ABL-expressing cells even under normoxia, coinciding with enhanced glutaminolysis which occurred in an HIF1/2-dependent manner. Expression of the glutamine importer SLC1A5 was increased in BCR-ABL+ cells, coinciding with an increased susceptibility to the glutaminase inhibitor BPTES. Oxygen consumption rates also decreased upon BPTES treatment, indicating a glutamine dependency for oxidative phosphorylation. The current study suggests that BCR-ABL-positive cancer cells make use of enhanced glutamine metabolism to maintain TCA cell cycle activity in glycolytic cells.

Qian X, Zhao FQ
Regulatory roles of Oct proteins in the mammary gland.
Biochim Biophys Acta. 2016; 1859(6):812-9 [PubMed] Related Publications
The expression of Oct-1 and -2 and their binding to the octamer motif in the mammary gland are developmentally and hormonally regulated, consistent with the expression of milk proteins. Both of these transcription factors constitutively bind to the proximal promoter of the milk protein gene β-casein and might be involved in the inhibition or activation of promoter activity via interactions with other transcription factors or cofactors at different developmental stages. In particular, the lactogenic hormone prolactin and glucocorticoids induce Oct-1 and Oct-2 binding and interaction with both the signal transducer and activator of transcription 5 (STAT5) and the glucocorticoid receptor on the β-casein promoter to activate β-casein expression. In addition, increasing evidence has shown the involvement of another Oct factor, Oct-3/4, in mammary tumorigenesis, making Oct-3/4 an emerging prognostic marker of breast cancer and a molecular target for the gene-directed therapeutic intervention, prevention and treatment of breast cancer. This article is part of a Special Issue entitled: The Oct Transcription Factor Family, edited by Dr. Dean Tantin.

Cheng Y, Chikwava K, Wu C, et al.
LNK/SH2B3 regulates IL-7 receptor signaling in normal and malignant B-progenitors.
J Clin Invest. 2016; 126(4):1267-81 [PubMed] Free Access to Full Article Related Publications
Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk ALL commonly associated with alterations that affect the tyrosine kinase pathway, tumor suppressors, and lymphoid transcription factors. Loss-of-function mutations in the gene-encoding adaptor protein LNK (also known as SH2B3) are found in Ph-like ALLs; however, it is not clear how LNK regulates normal B cell development or promotes leukemogenesis. Here, we have shown that combined loss of Lnk and tumor suppressors Tp53 or Ink4a/Arf in mice triggers a highly aggressive and transplantable precursor B-ALL. Tp53-/-Lnk-/- B-ALLs displayed similar gene expression profiles to human Ph-like B-ALLs, supporting use of this model for preclinical and molecular studies. Preleukemic Tp53-/-Lnk-/- pro-B progenitors were hypersensitive to IL-7, exhibited marked self-renewal in vitro and in vivo, and were able to initiate B-ALL in transplant recipients. Mechanistically, we demonstrated that LNK regulates pro-B progenitor homeostasis by attenuating IL-7-stimuated JAK/STAT5 signaling via a direct interaction with phosphorylated JAK3. Moreover, JAK inhibitors were effective in prolonging survival of mice transplanted with Lnk-/-Tp53-/- leukemia. Additionally, synergistic administration of PI3K/mTOR and JAK inhibitors further abrogated leukemia development. Hence, our results suggest that LNK suppresses IL-7R/JAK/STAT signaling to restrict pro-/pre-B progenitor expansion and leukemia development, providing a pathogenic mechanism and a potential therapeutic approach for B-ALLs with LNK mutations.

Chen KH, Walker AM
Prolactin inhibits a major tumor-suppressive function of wild type BRCA1.
Cancer Lett. 2016; 375(2):293-302 [PubMed] Related Publications
Even though mutations in the tumor suppressor, BRCA1, markedly increase the risk of breast and ovarian cancer, most breast and ovarian cancers express wild type BRCA1. An important question is therefore how the tumor-suppressive function of normal BRCA1 is overcome during development of most cancers. Because prolactin promotes these and other cancers, we investigated the hypothesis that prolactin interferes with the ability of BRCA1 to inhibit the cell cycle. Examining six different cancer cell lines with wild type BRCA1, and making use of both prolactin and the growth-inhibiting selective prolactin receptor modulator, S179D PRL, we demonstrate that prolactin activation of Stat5 results in the formation of a complex between phospho-Stat5 and BRCA1. Formation of this complex does not interfere with nuclear translocation or binding of BRCA1 to the p21 promoter, but does interfere with the ability of BRCA1 to transactivate the p21 promoter. Overexpression of a dominant-negative Stat5 in prolactin-stimulated cells resulted in increased p21 expression. We conclude that prolactin inhibits a major tumor-suppressive function of BRCA1 by interfering with BRCA1's upregulation of expression of the cell cycle inhibitor, p21.

Lee H, Hwang SJ, Kim HR, et al.
Neurofibromatosis 2 (NF2) controls the invasiveness of glioblastoma through YAP-dependent expression of CYR61/CCN1 and miR-296-3p.
Biochim Biophys Acta. 2016; 1859(4):599-611 [PubMed] Related Publications
Glioblastoma multiforme (GBM) is the most common and aggressive type of primary brain tumor derived from non-neuronal glial cells. Neurofibromatosis 2 (NF2) protein, also termed as merlin, is a well-known tumor suppressor; however, the molecular mechanism underlying this effect has not yet been fully defined. To investigate the role of NF2 in the invasiveness of GBM, we used two GBM cell lines: NF2-expressing T98G cells and NF2-deficient A172 cells. Knockdown of NF2 increased the invasiveness of T98G cells, whereas NF2-overexpressing A172 cells showed decreased invasive activity. Moreover, re-expression of NF2 reversed the high invasiveness of NF2-silenced T98G cells, indicating that NF2 negatively regulates GBM invasiveness. We further found that the NF2-mediated regulation of invasiveness was dependent on YAP and TEAD2 expression levels. NF2 also controlled the expression of YAP targets, including cysteine-rich angiogenic inducer 61 (CYR61/CCN1), by regulating the nuclear localization of YAP. Silencing of CYR61/CCN1 blocked the increased invasiveness of T98G cells, suggesting that CYR61/CCN1 is required for NF2-mediated invasiveness. Through microRNA microarray analysis, we found that NF2 negatively regulates the expression of miR-296-3p. Overexpression of miR-296-3p suppressed the expression of STAT5A, induced the phosphorylation of STAT3 by downregulating SOCS2, and increased the invasiveness of T98G cells. Taken together, we demonstrate that NF2 negatively controls the invasiveness of GBM through YAP-dependent induction of CYR61/CCN1 and miR-296-3p.

López C, Bergmann AK, Paul U, et al.
Genes encoding members of the JAK-STAT pathway or epigenetic regulators are recurrently mutated in T-cell prolymphocytic leukaemia.
Br J Haematol. 2016; 173(2):265-73 [PubMed] Related Publications
T-cell prolymphocytic leukaemia (T-PLL) is an aggressive leukaemia. The primary genetic alteration in T-PLL are the inv(14)(q11q32)/t(14;14)(q11;q32) leading to TRD/TRA-TCL1A fusion, or the t(X;14)(q28;q11) associated with TRD/TRA-MTCP1 fusion. However, additional cooperating abnormalities are necessary for emergence of the full neoplastic phenotype. Though the pattern of secondary chromosomal aberrations is remarkably conserved, targets of the changes are largely unknown. We analysed a cohort of 43 well-characterized T-PLL for hotspot mutations in the genes JAK3, STAT5B and RHOA. Additionally, we selected a subset of 23 T-PLL cases for mutational screening of 54 genes known to be recurrently mutated in T-cell and other haematological neoplasms. Activating mutations in the investigated regions of the JAK3 and STAT5B genes were detected in 30% (13/43) and 21% (8/39) of the cases, respectively, and were mutually exclusive. Further, we identified mutations in the genes encoding the epigenetic regulators EZH2 in 13% (3/23), TET2 in 17% (4/23) and BCOR in 9% (2/23) of the cases. We confirmed that the JAK-STAT pathway is a major mutational target, and identified epigenetic regulators recurrently mutated in T-PLL. These findings complement the mutational spectrum of secondary aberrations in T-PLL and underscore the potential therapeutical relevance of epigenetic regulators in T-PLL.

Kim C, Baek SH, Um JY, et al.
Resveratrol attenuates constitutive STAT3 and STAT5 activation through induction of PTPε and SHP-2 tyrosine phosphatases and potentiates sorafenib-induced apoptosis in renal cell carcinoma.
BMC Nephrol. 2016; 17:19 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Signal transducers and activators of transcription (STAT) proteins are critical transcription factor that are aberrantly activated in various types of malignancies, including renal cell carcinoma (RCC).
METHODS: We investigated the effect of resveratrol (RES), an edible polyphenol phytoalexin on STAT3 and STAT5 activation cascade in both Caki-1 and 786-O RCC cell lines.
RESULTS: We found that RES suppressed both constitutive STAT3 (tyrosine residue 705 and serine residue 727) and STAT5 (tyrosine residue 694 and 699) activation, which correlated with the suppression of the upstream kinases (JAK1, JAK2, and c-Src) in RCC. Also, RES abrogated DNA binding capacity and nuclear translocation of these two transcription factors. RES-induced an increased expression of PTPε and SHP-2 and the deletion of these two genes by small interfering RNA abolished the ability of RES to inhibit STAT3 activation, suggesting the critical role of both PTPε and SHP-2 in its possible mechanism of action. Moreover, RES induced S phase cell cycle arrest, caused induction of apoptosis, loss of mitochondrial membrane potential, and suppressed colony formation in RCC. We also found that RES downregulated the expression of STAT3/5-regulated antiapoptotic, proliferative, and metastatic gene products; and this correlated with induction of caspase-3 activation and anti-invasive activity. Beside, RES potentiated sorafenib induced inhibitory effect on constitutive STAT3 and STAT5 phosphorylation, apoptotic effects in 786-O cells, and this correlated with down-regulation of various oncogenic gene products.
CONCLUSION: Overall, our results suggest that RES is a blocker of both STAT3 and STAT5 activation and thus may exert potential growth inhibitory effects against RCC cells.

Gotthardt D, Putz EM, Grundschober E, et al.
STAT5 Is a Key Regulator in NK Cells and Acts as a Molecular Switch from Tumor Surveillance to Tumor Promotion.
Cancer Discov. 2016; 6(4):414-29 [PubMed] Related Publications
UNLABELLED: Natural killer (NK) cells are tightly regulated by the JAK-STAT signaling pathway and cannot survive in the absence of STAT5. We now report that STAT5-deficient NK cells can be rescued by overexpression of BCL2. Our experiments define STAT5 as a master regulator of NK-cell proliferation and lytic functions. Although NK cells are generally responsible for killing tumor cells, the rescued STAT5-deficient NK cells promote tumor formation by producing enhanced levels of the angiogenic factor VEGFA. The importance of VEGFA produced by NK cells was verified by experiments with a conditional knockout of VEGFA in NK cells. We show that STAT5 normally represses the transcription of VEGFA in NK cells, in both mice and humans. These findings reveal that STAT5-directed therapies may have negative effects: In addition to impairing NK-cell-mediated tumor surveillance, they may even promote tumor growth by enhancing angiogenesis.
SIGNIFICANCE: The importance of the immune system in effective cancer treatment is widely recognized. We show that the new signal interceptors targeting the JAK-STAT5 pathway may have dangerous side effects that must be taken into account in clinical trials: inhibiting JAK-STAT5 has the potential to promote tumor growth by enhancing NK-cell-mediated angiogenesis.

Kwakkenbos MJ, van Helden PM, Beaumont T, Spits H
Stable long-term cultures of self-renewing B cells and their applications.
Immunol Rev. 2016; 270(1):65-77 [PubMed] Free Access to Full Article Related Publications
Monoclonal antibodies are essential therapeutics and diagnostics in a large number of diseases. Moreover, they are essential tools in all sectors of life sciences. Although the great majority of monoclonal antibodies currently in use are of mouse origin, the use of human B cells to generate monoclonal antibodies is increasing as new techniques to tap the human B cell repertoire are rapidly emerging. Cloned lines of immortalized human B cells are ideal sources of monoclonal antibodies. In this review, we summarize our studies to the regulation of the replicative life span, differentiation, and maturation of B cells that led to the development of a platform that uses immortalization of human B cells by in vitro genetic modification for antibody development. We describe a number of human antibodies that were isolated using this platform and the application of the technique in other species. We also discuss the use of immortalized B cells as antigen-presenting cells for the discovery of tumor neoantigens.

Chougule RA, Kazi JU, Rönnstrand L
FYN expression potentiates FLT3-ITD induced STAT5 signaling in acute myeloid leukemia.
Oncotarget. 2016; 7(9):9964-74 [PubMed] Free Access to Full Article Related Publications
FYN is a non-receptor tyrosine kinase belonging to the SRC family of kinases, which are frequently over-expressed in human cancers, and play key roles in cancer biology. SRC has long been recognized as an important oncogene, but little attention has been given to its other family members. In this report, we have studied the role of FYN in FLT3 signaling in respect to acute myeloid leukemia (AML). We observed that FYN displays a strong association with wild-type FLT3 as well as oncogenic FLT3-ITD and is dependent on the kinase activity of FLT3 and the SH2 domain of FYN. We identified multiple FYN binding sites in FLT3, which partially overlapped with SRC binding sites. To understand the role of FYN in FLT3 signaling, we generated FYN overexpressing cells. We observed that expression of FYN resulted in slightly enhanced phosphorylation of AKT, ERK1/2 and p38 in response to ligand stimulation. Furthermore, FYN expression led to a slight increase in FLT3-ITD-dependent cell proliferation, but potent enhancement of STAT5 phosphorylation as well as colony formation. We also observed that FYN expression is deregulated in AML patient samples and that higher expression of FYN, in combination with FLT3-ITD mutation, resulted in enrichment of the STAT5 signaling pathway and correlated with poor prognosis in AML. Taken together our data suggest that FYN cooperates with oncogenic FLT3-ITD in cellular transformation by selective activation of the STAT5 pathway. Therefore, inhibition of FYN, in combination with FLT3 inhibition, will most likely be beneficial for this group of AML patients.

Wang J, Rouse C, Jasper JS, Pendergast AM
ABL kinases promote breast cancer osteolytic metastasis by modulating tumor-bone interactions through TAZ and STAT5 signaling.
Sci Signal. 2016; 9(413):ra12 [PubMed] Free Access to Full Article Related Publications
Bone metastases occur in up to 70% of advanced breast cancer. For most patients with breast cancer, bone metastases are predominantly osteolytic. Interactions between tumor cells and stromal cells in the bone microenvironment drive osteolytic bone metastasis, a process that requires the activation of osteoclasts, cells that break down bone. We report that ABL kinases promoted metastasis of breast cancer cells to bone by regulating the crosstalk between tumor cells and the bone microenvironment. ABL kinases protected tumor cells from apoptosis induced by TRAIL (TNF-related apoptosis-inducing ligand), activated the transcription factor STAT5, and promoted osteolysis through the STAT5-dependent expression of genes encoding the osteoclast-activating factors interleukin-6 (IL-6) and matrix metalloproteinase 1 (MMP1). Furthermore, in breast cancer cells, ABL kinases increased the abundance of the Hippo pathway mediator TAZ and the expression of TAZ-dependent target genes that promote bone metastasis. Knockdown of ABL kinases or treatment with ABL-specific allosteric inhibitor impaired osteolytic metastasis of breast cancer cells in mice. These findings revealed a role for ABL kinases in regulating tumor-bone interactions and provide a rationale for using ABL-specific inhibitors to limit breast cancer metastasis to bone.

Kanderova V, Kuzilkova D, Stuchly J, et al.
High-resolution Antibody Array Analysis of Childhood Acute Leukemia Cells.
Mol Cell Proteomics. 2016; 15(4):1246-61 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Acute leukemia is a disease pathologically manifested at both genomic and proteomic levels. Molecular genetic technologies are currently widely used in clinical research. In contrast, sensitive and high-throughput proteomic techniques for performing protein analyses in patient samples are still lacking. Here, we used a technology based on size exclusion chromatography followed by immunoprecipitation of target proteins with an antibody bead array (Size Exclusion Chromatography-Microsphere-based Affinity Proteomics, SEC-MAP) to detect hundreds of proteins from a single sample. In addition, we developed semi-automatic bioinformatics tools to adapt this technology for high-content proteomic screening of pediatric acute leukemia patients.To confirm the utility of SEC-MAP in leukemia immunophenotyping, we tested 31 leukemia diagnostic markers in parallel by SEC-MAP and flow cytometry. We identified 28 antibodies suitable for both techniques. Eighteen of them provided excellent quantitative correlation between SEC-MAP and flow cytometry (p< 0.05). Next, SEC-MAP was applied to examine 57 diagnostic samples from patients with acute leukemia. In this assay, we used 632 different antibodies and detected 501 targets. Of those, 47 targets were differentially expressed between at least two of the three acute leukemia subgroups. The CD markers correlated with immunophenotypic categories as expected. From non-CD markers, we found DBN1, PAX5, or PTK2 overexpressed in B-cell precursor acute lymphoblastic leukemias, LAT, SH2D1A, or STAT5A overexpressed in T-cell acute lymphoblastic leukemias, and HCK, GLUD1, or SYK overexpressed in acute myeloid leukemias. In addition, OPAL1 overexpression corresponded to ETV6-RUNX1 chromosomal translocation.In summary, we demonstrated that SEC-MAP technology is a powerful tool for detecting hundreds of proteins in clinical samples obtained from pediatric acute leukemia patients. It provides information about protein size and reveals differences in protein expression between particular leukemia subgroups. Forty-seven of SEC-MAP identified targets were validated by other conventional method in this study.

Turakhia SK, Murugesan G, Cotta CV, Theil KS
Thrombocytosis and STAT5 activation in chronic myelogenous leukaemia are not associated with JAK2 V617F or calreticulin mutations.
J Clin Pathol. 2016; 69(8):713-9 [PubMed] Related Publications
AIMS: Marked thrombocytosis is uncommon in chronic myelogenous leukaemia (CML) but may be associated with mutation of JAK2 V617F, calreticulin (CALR) and/or phospho-STAT5 (p-STAT5) activation in other myeloproliferative neoplasms (MPNs), particularly essential thrombocythaemia (ET). We investigated the JAK2 V617F, CALR and STAT5 activation status in patients with CML and thrombocytosis (CML-T) that mimicked ET, trying to identify a common mechanism for thrombocytosis in MPN.
METHODS: Blood and bone marrow morphological findings were reviewed from seven CML-T, four otherwise typical CML and one CML in blast phase. All cases were analysed for BCR-ABL1, JAK2 V617F and CALR exon 9 mutation and p-STAT5 expression.
RESULTS: Four of seven cases of CML-T had marked thrombocytosis (>1000×10(9)/L). Eleven of 12 cases had megakaryocyte morphology typical for CML. All cases were BCR-ABL1 positive. Eleven of 12 cases were negative for JAK2 V617F, while STAT5 was activated in six of seven CML-T and in four of five CML cases. No case had a detectable CALR exon 9 mutation. One case of CML developed ET-like morphology and had JAK2 V617F detected while in molecular remission for CML.
CONCLUSIONS: Detection of BCR-ABL1 is critical in the distinction of ET from CML. Thrombocytosis and STAT5 activation in CML-T are not consistently associated with CALR exon 9 or JAK2 V617F mutation.

Rani A, Murphy JJ
STAT5 in Cancer and Immunity.
J Interferon Cytokine Res. 2016; 36(4):226-37 [PubMed] Related Publications
Signal transducers and activators of transcription 5 (STAT5a and STAT5b) are highly homologous proteins that are encoded by 2 separate genes and are activated by Janus-activated kinases (JAK) downstream of cytokine receptors. STAT5 proteins are activated by a wide variety of hematopoietic and nonhematopoietic cytokines and growth factors, all of which use the JAK-STAT signalling pathway as their main mode of signal transduction. STAT5 proteins critically regulate vital cellular functions such as proliferation, differentiation, and survival. The physiological importance of STAT5 proteins is underscored by the plethora of primary human tumors that have aberrant constitutive activation of these proteins, which significantly contributes to tumor cell survival and malignant progression of disease. STAT5 plays an important role in the maintenance of normal immune function and homeostasis, both of which are regulated by specific members of IL-2 family of cytokines, which share a common gamma chain (γ(c)) in their receptor complex. STAT5 critically mediates the biological actions of members of the γ(c) family of cytokines in the immune system. Essentially, STAT5 plays a critical role in the function and development of Tregs, and consistently activated STAT5 is associated with a suppression in antitumor immunity and an increase in proliferation, invasion, and survival of tumor cells. Thus, therapeutic targeting of STAT5 is promising in cancer.

Miltiades P, Lamprianidou E, Vassilakopoulos TP, et al.
The Stat3/5 Signaling Biosignature in Hematopoietic Stem/Progenitor Cells Predicts Response and Outcome in Myelodysplastic Syndrome Patients Treated with Azacitidine.
Clin Cancer Res. 2016; 22(8):1958-68 [PubMed] Related Publications
PURPOSE: Azacitidine is the mainstay of high-risk myelodysplastic syndromes (MDS) therapy, but molecular predictors of response and the mechanisms of resistance to azacitidine remain largely unidentified. Deregulation of signaling via Stat3 and Stat5 in acute myeloid leukemia (AML) is associated with aggressive disease. Numerous genes involved in cell signaling are aberrantly methylated in MDS, yet the alterations and the effect of azacitidine treatment on Stat3/5 signaling in high-risk MDS have not been explored.
EXPERIMENTAL DESIGN: We assessed longitudinally constitutive and ligand-induced phospho-Stat3/5 signaling responses by multiparametric flow cytometry in 74 patients with MDS and low blast count AML undergoing azacitidine therapy. Pretreatment Stat3/5 signaling profiles in CD34(+)cells were grouped by unsupervised clustering. The differentiation stage and the molecular properties of the CD34(+)G-CSF-inducible Stat3/5 double-positive subpopulation were performed by flow cytometry and quantitative real-time PCR in isolated MDS progenitors.
RESULTS: The pretreatment Stat3/5 signaling profiles in CD34(+)cells correlated strongly with response and cytogenetics and independently predicted event-free survival. We further identified a CD34(+)G-CSF-inducible Stat3/5 double-positive subpopulation (DP subset) whose pretreatment levels were inversely associated with treatment response and cytogenetics. The kinetics of the DP subset followed the response to azacitidine and the disease course, whereas its molecular characteristics and cellular hierarchy were consistent with a leukemia propagating cell phenotype.
CONCLUSIONS: Our findings provide a novel link among Stat3/5 signaling and MDS pathobiology and suggest that the Stat3/5 signaling biosignature may serve as both a response biomarker and treatment target.

Kang DY, Darvin P, Yoo YB, et al.
Methylsulfonylmethane inhibits HER2 expression through STAT5b in breast cancer cells.
Int J Oncol. 2016; 48(2):836-42 [PubMed] Related Publications
Breast cancer is the most common cancer in women globally. The factors that increase risk include: late age at first birth, alcohol, radiation exposure, family history of breast cancer, and postmenopausal hormone therapy. Numerous drugs are being developed to treat breast cancer. Among them, Herceptin is used for the treatment of human epidermal growth factor receptor 2 (HER2)-positive cases and targets HER2 effectively and efficiently, but it is very expensive. Methylsulfonylmethane (MSM) is an organic sulfur-containing natural compound having no reported toxicity. We examined MSM in breast cancer cell lines and found it inhibited the proliferation of estrogen receptor-positive and HER2-positive breast cancer cells in a dose-dependent manner. It also suppressed the activation of STAT5b and expression of HER2 in breast cancer cells. We determined the STAT5b binding site (GAS element) in the HER2 gene. Detailed analysis showed that MSM decreased the ability of STAT5b to bind the promoter of the HER2 gene and a luciferase assay demonstrated reduced activity. We confirmed that MSM can effectively regulate STAT5b, and thereby decrease HER2 expression. Therefore, we recommend the use of MSM as an inhibitor for the management of HER2-positive breast cancers.

Francis OL, Milford TA, Martinez SR, et al.
A novel xenograft model to study the role of TSLP-induced CRLF2 signals in normal and malignant human B lymphopoiesis.
Haematologica. 2016; 101(4):417-26 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Thymic stromal lymphopoietin (TSLP) stimulates in-vitro proliferation of human fetal B-cell precursors. However, its in-vivo role during normal human B lymphopoiesis is unknown. Genetic alterations that cause overexpression of its receptor component, cytokine receptor-like factor 2 (CRLF2), lead to high-risk B-cell acute lymphoblastic leukemia implicating this signaling pathway in leukemogenesis. We show that mouse thymic stromal lymphopoietin does not stimulate the downstream pathways (JAK/STAT5 and PI3K/AKT/mTOR) activated by the human cytokine in primary high-risk leukemia with overexpression of the receptor component. Thus, the utility of classic patient-derived xenografts for in-vivo studies of this pathway is limited. We engineered xenograft mice to produce human thymic stromal lymphopoietin (+T mice) by injection with stromal cells transduced to express the cytokine. Control (-T) mice were produced using stroma transduced with control vector. Normal levels of human thymic stromal lymphopoietin were achieved in sera of +T mice, but were undetectable in -T mice. Patient-derived xenografts generated from +T as compared to -T mice showed a 3-6-fold increase in normal human B-cell precursors that was maintained through later stages of B-cell development. Gene expression profiles in high-risk B-cell acute lymphoblastic leukemia expanded in +T mice indicate increased mTOR pathway activation and are more similar to the original patient sample than those from -T mice. +T/-T xenografts provide a novel pre-clinical model for understanding this pathway in B lymphopoiesis and identifying treatments for high-risk B-cell acute lymphoblastic leukemia with overexpression of cytokine-like factor receptor 2.

Sadovnik I, Hoelbl-Kovacic A, Herrmann H, et al.
Identification of CD25 as STAT5-Dependent Growth Regulator of Leukemic Stem Cells in Ph+ CML.
Clin Cancer Res. 2016; 22(8):2051-61 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
PURPOSE: In chronic myelogenous leukemia (CML), leukemic stem cells (LSC) represent a critical target of therapy. However, little is known about markers and targets expressed by LSCs. The aim of this project was to identify novel relevant markers of CML LSCs.
EXPERIMENTAL DESIGN: CML LSCs were examined by flow cytometry, qPCR, and various bioassays. In addition, we examined the multipotent CD25(+)CML cell line KU812.
RESULTS: In contrast to normal hematopoietic stem cells, CD34(+)/CD38(-)CML LSCs expressed the IL-2 receptor alpha chain, IL-2RA (CD25). STAT5 was found to induce expression of CD25 in Lin(-)/Sca-1(+)/Kit(+)stem cells in C57Bl/6 mice. Correspondingly, shRNA-induced STAT5 depletion resulted in decreased CD25 expression in KU812 cells. Moreover, the BCR/ABL1 inhibitors nilotinib and ponatinib were found to decrease STAT5 activity and CD25 expression in KU812 cells and primary CML LSCs. A CD25-targeting shRNA was found to augment proliferation of KU812 cellsin vitroand their engraftmentin vivoin NOD/SCID-IL-2Rγ(-/-)mice. In drug-screening experiments, the PI3K/mTOR blocker BEZ235 promoted the expression of STAT5 and CD25 in CML cells. Finally, we found that BEZ235 produces synergistic antineoplastic effects on CML cells when applied in combination with nilotinib or ponatinib.
CONCLUSIONS: CD25 is a novel STAT5-dependent marker of CML LSCs and may be useful for LSC detection and LSC isolation in clinical practice and basic science. Moreover, CD25 serves as a growth regulator of CML LSCs, which may have biologic and clinical implications and may pave the way for the development of new more effective LSC-eradicating treatment strategies in CML.

Demosthenous C, Han JJ, Hu G, et al.
Loss of function mutations in PTPN6 promote STAT3 deregulation via JAK3 kinase in diffuse large B-cell lymphoma.
Oncotarget. 2015; 6(42):44703-13 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
PTPN6 (SHP1) is a tyrosine phosphatase that negatively controls the activity of multiple signaling pathways including STAT signaling, however role of mutated PTPN6 is not much known. Here we investigated whether PTPN6 might also be a potential target for diffuse large B cell lymphoma (DLBCL) and performed Sanger sequencing of the PTPN6 gene. We have identified missense mutations within PTPN6 (N225K and A550V) in 5% (2/38) of DLBCL tumors. Site directed mutagenesis was performed to mutate wild type (WT) PTPN6 and stable cell lines were generated by lentiviral transduction of PTPN6(WT), PTPN6(N225K) and PTPN6(A550V) constructs, and effects of WT or mutated PTPN6 on STAT3 signaling were analyzed. WT PTPN6 dephosphorylated STAT3, but had no effect on STAT1, STAT5 or STAT6 phosphorylation. Both PTPN6 mutants were unable to inhibit constitutive, as well as cytokines induced STAT3 activation. Both PTPN6 mutants also demonstrated reduced tyrosine phosphatase activity and exhibited enhanced STAT3 transactivation activity. Intriguingly, a lack of direct binding between STAT3 and WT or mutated PTPN6 was observed. However, compared to WT PTPN6, cells expressing PTPN6 mutants exhibited increased binding between JAK3 and PTPN6 suggesting a more dynamic interaction of PTPN6 with upstream regulators of STAT3. Consistent with this notion, both the mutants demonstrated increased resistance to JAK3 inhibitor, WHIP-154 relative to WT PTPN6. Overall, this is the first study, which demonstrates that N225K and A550V PTPN6 mutations cause loss-of-function leading to JAK3 mediated deregulation of STAT3 pathway and uncovers a mechanism that tumor cells can use to control PTPN6 substrate specificity.

Sasaki R, Ito S, Asahi M, Ishida Y
YM155 suppresses cell proliferation and induces cell death in human adult T-cell leukemia/lymphoma cells.
Leuk Res. 2015; 39(12):1473-9 [PubMed] Related Publications
Adult T-cell leukemia (ATL) is an aggressive malignancy of peripheral T cells infected with human T-cell leukemia virus type 1 (HTLV-1). The prognosis of patients with aggressive ATL remains poor because ATL cells acquire resistance to conventional cytotoxic agents. Therefore, development of novel agents is urgently needed. We examined the effects of YM155, sepantronium bromide, on cell proliferation and survival of ATL or HTLV-1-infected T-cell lines, S1T, MT-1, and MT-2. We found that YM155 suppressed cell proliferation in these cells and induced cell death in S1T and MT-1 cells. Both real-time quantitative polymerase chain reaction and immunoblot analyses showed suppression of survivin expression in S1T, MT-1, and MT-2 cells. In addition, we observed the cleavage of caspase-3 and poly(ADP-ribose) polymerase in YM155-treated S1T and MT-1 cells, indicating that YM155 induces caspase-dependent apoptosis in these cells. To clarify the mechanism of drug tolerance of MT-2 cells in terms of YM155-induced cell death, we examined intracellular signaling status in these cells. We found that STAT3, STAT5, and AKT were constitutively phosphorylated in MT-2 cells but not in S1T and MT-1 cells. Treatment with YM155 combined with the STAT3 inhibitor S3I-201 significantly suppressed cell proliferation compared to that with either YM155 or S3I-201 in MT-2 cells, indicating that STAT3 may play a role in tolerance of MT-2 cells to YM155 and that STAT3 may therefore be a therapeutic target for YM155-resistant ATL cells. These results suggest that YM155 presents potent antiproliferative and apoptotic effects via suppression of survivin in ATL cells in which STAT3 is not constitutively phosphorylated. YM155 merits further investigation as a potential chemotherapeutic agent for ATL.

Bertoli S, Boutzen H, David L, et al.
CDC25A governs proliferation and differentiation of FLT3-ITD acute myeloid leukemia.
Oncotarget. 2015; 6(35):38061-78 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
We investigated cell cycle regulation in acute myeloid leukemia cells expressing the FLT3-ITD mutated tyrosine kinase receptor, an underexplored field in this disease. Upon FLT3 inhibition, CDC25A mRNA and protein were rapidly down-regulated, while levels of other cell cycle proteins remained unchanged. This regulation was dependent on STAT5, arguing for FLT3-ITD-dependent transcriptional regulation of CDC25A. CDC25 inhibitors triggered proliferation arrest and cell death of FLT3-ITD as well as FLT3-ITD/TKD AC-220 resistant cells, but not of FLT3-wt cells. Consistently, RNA interference-mediated knock-down of CDC25A reduced the proliferation of FLT3-ITD cell lines. Finally, the clonogenic capacity of primary FLT3-ITD AML cells was reduced by the CDC25 inhibitor IRC-083864, while FLT3-wt AML and normal CD34+ myeloid cells were unaffected. In good agreement, in a cohort of 100 samples from AML patients with intermediate-risk cytogenetics, high levels of CDC25A mRNA were predictive of higher clonogenic potential in FLT3-ITD+ samples, not in FLT3-wt ones.Importantly, pharmacological inhibition as well as RNA interference-mediated knock-down of CDC25A also induced monocytic differentiation of FLT3-ITD positive cells, as judged by cell surface markers expression, morphological modifications, and C/EBPα phosphorylation. CDC25 inhibition also re-induced monocytic differentiation in primary AML blasts carrying the FLT3-ITD mutation, but not in blasts expressing wild type FLT3. Altogether, these data identify CDC25A as an early cell cycle transducer of FLT3-ITD oncogenic signaling, and as a promising target to inhibit proliferation and re-induce differentiation of FLT3-ITD AML cells.

Adam K, Lambert M, Lestang E, et al.
Control of Pim2 kinase stability and expression in transformed human haematopoietic cells.
Biosci Rep. 2015; 35(6) [PubMed] Article available free on PMC after 01/04/2017 Related Publications
The oncogenic Pim2 kinase is overexpressed in several haematological malignancies, such as multiple myeloma and acute myeloid leukaemia (AML), and constitutes a strong therapeutic target candidate. Like other Pim kinases, Pim2 is constitutively active and is believed to be essentially regulated through its accumulation. We show that in leukaemic cells, the three Pim2 isoforms have dramatically short half-lives although the longer isoform is significantly more stable than the shorter isoforms. All isoforms present a cytoplasmic localization and their degradation was neither modified by broad-spectrum kinase or phosphatase inhibitors such as staurosporine or okadaic acid nor by specific inhibition of several intracellular signalling pathways including Erk, Akt and mTORC1. Pim2 degradation was inhibited by proteasome inhibitors but Pim2 ubiquitination was not detected even by blocking both proteasome activity and protein de-ubiquitinases (DUBs). Moreover, Pyr41, an ubiquitin-activating enzyme (E1) inhibitor, did not stabilize Pim2, strongly suggesting that Pim2 was degraded by the proteasome without ubiquitination. In agreement, we observed that purified 20S proteasome particles could degrade Pim2 molecule in vitro. Pim2 mRNA accumulation in UT7 cells was controlled by erythropoietin (Epo) through STAT5 transcription factors. In contrast, the translation of Pim2 mRNA was not regulated by mTORC1. Overall, our results suggest that Pim2 is only controlled by its mRNA accumulation level. Catalytically active Pim2 accumulated in proteasome inhibitor-treated myeloma cells. We show that Pim2 inhibitors and proteasome inhibitors, such as bortezomib, have additive effects to inhibit the growth of myeloma cells, suggesting that Pim2 could be an interesting target for the treatment of multiple myeloma.

Čokić VP, Mitrović-Ajtić O, Beleslin-Čokić BB, et al.
Proinflammatory Cytokine IL-6 and JAK-STAT Signaling Pathway in Myeloproliferative Neoplasms.
Mediators Inflamm. 2015; 2015:453020 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
The recent JAK1/2 inhibitor trial in myeloproliferative neoplasms (MPNs) showed that reducing inflammation can be more beneficial than targeting gene mutants. We evaluated the proinflammatory IL-6 cytokine and JAK-STAT signaling pathway related genes in circulating CD34(+) cells of MPNs. Regarding laboratory data, leukocytosis has been observed in polycythemia vera (PV) and JAK2V617F mutation positive versus negative primary myelofibrosis (PMF) patients. Moreover, thrombocytosis was reduced by JAK2V617F allele burden in essential thrombocythemia (ET) and PMF. 261 significantly changed genes have been detected in PV, 82 in ET, and 94 genes in PMF. The following JAK-STAT signaling pathway related genes had augmented expression in CD34(+) cells of MPNs: CCND3 and IL23A regardless of JAK2V617F allele burden; CSF3R, IL6ST, and STAT1/2 in ET and PV with JAK2V617F mutation; and AKT2, IFNGR2, PIM1, PTPN11, and STAT3 only in PV. STAT5A gene expression was generally reduced in MPNs. IL-6 cytokine levels were increased in plasma, as well as IL-6 protein levels in bone marrow stroma of MPNs, dependent on JAK2V617F mutation presence in ET and PMF patients. Therefore, the JAK2V617F mutant allele burden participated in inflammation biomarkers induction and related signaling pathways activation in MPNs.

Lindblad O, Chougule RA, Moharram SA, et al.
The role of HOXB2 and HOXB3 in acute myeloid leukemia.
Biochem Biophys Res Commun. 2015; 467(4):742-7 [PubMed] Related Publications
Acute myeloid leukemia (AML) is a heterogeneous aggressive disease and the most common form of adult leukemia. Mutations in the type III receptor tyrosine kinase FLT3 are found in more than 30% of AML patients. Drugs against FLT3 have been developed for the treatment of AML, but they lack specificity, show poor response and lead to the development of a resistant phenotype upon treatment. Therefore, a deeper understanding of FLT3 signaling will facilitate identification of additional pharmacological targets in FLT3-driven AML. In this report, we identify HOXB2 and HOXB3 as novel regulators of oncogenic FLT3-ITD-driven AML. We show that HOXB2 and HOXB3 expression is upregulated in a group of AML patients carrying FLT3-ITD. Overexpression of HOXB2 or HOXB3 in mouse pro-B cells resulted in decreased FLT3-ITD-dependent cell proliferation as well as colony formation and increased apoptosis. Expression of HOXB2 or HOXB3 resulted in a significant decrease in FLT3-ITD-induced AKT, ERK, p38 and STAT5 phosphorylation. Our data suggest that HOXB2 and HOXB3 act as tumor suppressors in FLT3-ITD driven AML.

Mulero-Navarro S, Sevilla A, Roman AC, et al.
Myeloid Dysregulation in a Human Induced Pluripotent Stem Cell Model of PTPN11-Associated Juvenile Myelomonocytic Leukemia.
Cell Rep. 2015; 13(3):504-15 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Somatic PTPN11 mutations cause juvenile myelomonocytic leukemia (JMML). Germline PTPN11 defects cause Noonan syndrome (NS), and specific inherited mutations cause NS/JMML. Here, we report that hematopoietic cells differentiated from human induced pluripotent stem cells (hiPSCs) harboring NS/JMML-causing PTPN11 mutations recapitulated JMML features. hiPSC-derived NS/JMML myeloid cells exhibited increased signaling through STAT5 and upregulation of miR-223 and miR-15a. Similarly, miR-223 and miR-15a were upregulated in 11/19 JMML bone marrow mononuclear cells harboring PTPN11 mutations, but not those without PTPN11 defects. Reducing miR-223's function in NS/JMML hiPSCs normalized myelogenesis. MicroRNA target gene expression levels were reduced in hiPSC-derived myeloid cells as well as in JMML cells with PTPN11 mutations. Thus, studying an inherited human cancer syndrome with hiPSCs illuminated early oncogenesis prior to the accumulation of secondary genomic alterations, enabling us to discover microRNA dysregulation, establishing a genotype-phenotype association for JMML and providing therapeutic targets.

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