Constitutively active STAT5 recruits p53 to alternative transcriptional targets in myeloid cancers
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ABSTRACT: In several cancer types, STAT (Signal transducer and activator of transcription) transcription factors are constitutively activated. We previously identified a target gene, LPP/miR-28 (LIM domain containing preferred translocation partner in lipoma), induced by constitutive activation of STAT5, but not by transient cytokine-activated STAT5. Here, we demonstrate in transformed hematopoietic cells that binding of both STAT5B and p53 to chromatin is required for transcriptional activity of an alternative LPP/miR-28 promoter. Using a genome-wide approach, we identified 463 genomic positions at promoter regions where STAT5B and p53 are co-localized on the chromatin. At these positions, p53 chromatin binding is dependent on persistent STAT5B activation. The transcriptional activity of selected promoters bound by STAT5B and p53 was significantly changed upon STAT5 or p53 inhibition, and the transcription of these target genes is frequently altered in platelets of myeloproliferative neoplasm patients harboring mutations constitutively activating STAT5. These data suggest that the constitutive STAT5 activation recruits p53 in cancer cells and thereby activates oncogenic transcriptional programs.
Project description:In several cancer types, STAT (Signal transducer and activator of transcription) transcription factors are constitutively activated. We previously identified a target gene, LPP/miR-28 (LIM domain containing preferred translocation partner in lipoma), induced by constitutive activation of STAT5, but not by transient cytokine-activated STAT5. Here, we demonstrate in transformed hematopoietic cells that binding of both STAT5B and p53 to chromatin is required for transcriptional activity of an alternative LPP/miR-28 promoter. Using a genome-wide approach, we identified 463 genomic positions at promoter regions where STAT5B and p53 are co-localized on the chromatin. At these positions, p53 chromatin binding is dependent on persistent STAT5B activation. The transcriptional activity of selected promoters bound by STAT5B and p53 was significantly changed upon STAT5 or p53 inhibition, and the transcription of these target genes is frequently altered in platelets of myeloproliferative neoplasm patients harboring mutations constitutively activating STAT5. These data suggest that the constitutive STAT5 activation recruits p53 in cancer cells and thereby activates oncogenic transcriptional programs. STAT5B and p53 ChIP-chip with or without JAK2 inhibition (ruxolitinib) to inhibit STAT5 phosphorylation and DNA binding.
Project description:STAT5 is critical for differentiation, proliferation and survival of progenitor B cells suggesting a possible role in Acute Lymphoblastic Leukemia (ALL). Herein, we show increased expression of activated STAT5 in ALL patients, which correlates with treatment outcome. Mutations in Ebf1 and Pax5, genes critical for B cell development have also been identified in human ALL. To determine whether mutations in Ebf1 or Pax5 synergize with STAT5 activation to induce ALL we crossed mice expressing a constitutively active form of STAT5 (Stat5b-CA) with mice heterozygous for Ebf1 or Pax5. Haploinsufficiency of either Pax5 or Ebf1 synergized with Stat5b-CA to rapidly induce ALL in 100% of the mice. The leukemic cells displayed reduced expression of both Pax5 and Ebf1 but this had little affect on most EBF1 or PAX5 target genes. However, a subset of these genes was deregulated and included a large percentage of potential tumor suppressor genes and oncogenes. Further, most of these genes appear to be jointly regulated by both EBF1 and PAX5. Our findings suggest a model whereby small perturbations in a self-reinforcing network of transcription factors critical for B cell development, specifically PAX5 and EBF1, cooperate with STAT5 activation to initiate ALL. Gene expression profiling was performed on cells isolated from lymph nodes of Stat5b-CA x Ebf1+/- and Stat5b-CA x Rag2-/- leukemic mice and pre B cells sorted from bone marrow of C57BL/6 mice and Stat5b-CA transgenic mice. 17 Samples.
Project description:PolyA-selected nuclear RNA isolated from livers of adult male mice administered AAV8-STAT5ca was analyzed by RNA-seq to determine the impact of constitutive STAT5 activation on the expression of sex-biased genes in male mouse liver. This is part of a study entitled 'Constitutively active STAT5b feminizes mouse liver gene expression', where delivery of constitutively active STAT5 (STAT5CA) to male mouse liver was shown to induce widespread feminization of the liver, with extensive induction of female-biased genes and repression of male-biased genes, largely mimicking results obtained when male mice are given GH as a continuous infusion. Many of the STAT5CA-responding genes were associated with nearby (< 50 kb) sites of STAT5 binding to liver chromatin, supporting the proposed direct role of persistently active STAT5 in continuous GH-induced liver feminization. The feminizing effects of STAT5CA were dose-dependent; moreover, at higher levels, STAT5CA overexpression resulted in some histopathology, including hepatocyte hyperplasia, and increased karyomegaly and multinuclear hepatocytes. Together, these findings establish that the persistent activation of STAT5 by GH that characterizes female liver is by itself sufficient to account for the sex-dependent expression of a majority of hepatic sex-biased genes.
Project description:PolyA-selected total RNA isolated from livers of adult male mice administered AAV8-STAT5ca was analyzed by RNA-seq to determine the impact of constitutive STAT5 activation on the expression of sex-biased genes in male mouse liver. This is part of a study entitled 'Constitutively active STAT5b feminizes mouse liver gene expression', where delivery of constitutively active STAT5 (STAT5CA) to male mouse liver was shown to induce widespread feminization of the liver, with extensive induction of female-biased genes and repression of male-biased genes, largely mimicking results obtained when male mice are given GH as a continuous infusion. Many of the STAT5CA-responding genes were associated with nearby (< 50 kb) sites of STAT5 binding to liver chromatin, supporting the proposed direct role of persistently active STAT5 in continuous GH-induced liver feminization. The feminizing effects of STAT5CA were dose-dependent; moreover, at higher levels, STAT5CA overexpression resulted in some histopathology, including hepatocyte hyperplasia, and increased karyomegaly and multinuclear hepatocytes. Together, these findings establish that the persistent activation of STAT5 by GH that characterizes female liver is by itself sufficient to account for the sex-dependent expression of a majority of hepatic sex-biased genes.
Project description:Transcription factor Stat5 is constitutively active in human prostate cancer but not in normal prostate epithelium. Stat5 activation is associated with prostate cancer lesions of high histological grades, and is present in the majority of castration-resistant recurrent human prostate cancers. The molecular mechnisms underlying constitutive activation of Stat5 in primary and recurrent human prostate cancer are currently unclear. We used microarrays to detail gene expression regulated by Stat5 in human prostate cancer cells.
Project description:Transcription factor Stat5 is constitutively active in human prostate cancer but not in normal prostate epithelium. Stat5 activation is associated with prostate cancer lesions of high histological grades, and is present in the majority of castration-resistant recurrent human prostate cancers. The molecular mechnisms underlying constitutive activation of Stat5 in primary and recurrent human prostate cancer are currently unclear. We used microarrays to detail gene expression regulated by Stat5 in human prostate cancer cells. DU145 human prostate cancer cells were transfected with Stat5a/b siRNA or scramble siRNA as control. After 48 h, the cells were harvested and total RNA was prepared for Affymetrix microarrays.
Project description:STAT5 is critical for differentiation, proliferation and survival of progenitor B cells suggesting a possible role in Acute Lymphoblastic Leukemia (ALL). Herein, we show increased expression of activated STAT5 in ALL patients, which correlates with treatment outcome. Mutations in Ebf1 and Pax5, genes critical for B cell development have also been identified in human ALL. To determine whether mutations in Ebf1 or Pax5 synergize with STAT5 activation to induce ALL we crossed mice expressing a constitutively active form of STAT5 (Stat5b-CA) with mice heterozygous for Ebf1 or Pax5. Haploinsufficiency of either Pax5 or Ebf1 synergized with Stat5b-CA to rapidly induce ALL in 100% of the mice. The leukemic cells displayed reduced expression of both Pax5 and Ebf1 but this had little affect on most EBF1 or PAX5 target genes. However, a subset of these genes was deregulated and included a large percentage of potential tumor suppressor genes and oncogenes. Further, most of these genes appear to be jointly regulated by both EBF1 and PAX5. Our findings suggest a model whereby small perturbations in a self-reinforcing network of transcription factors critical for B cell development, specifically PAX5 and EBF1, cooperate with STAT5 activation to initiate ALL.
Project description:STAT5A and STAT5B proteins belong to the family of signal transducers and activators of transcription. They are encoded by 2 separate genes with 91% identity in their amino acid sequences. Despite their high degree of conservation, STAT5A and STAT5B exert non-redundant functions, resulting at least in part from differences in target gene activation. To better characterize the differential contribution of STAT5A and STAT5B in gene regulation, we performed single or double knock-down of STAT5A and STAT5B using small interfering RNA. Subsequent gene expression profiling and RT-qPCR analyses of IL-3-stimulated Ba/F3-beta cells led to the identification of putative novel STAT5 target genes. Chromatin immunoprecipitation assays analyzing the corresponding gene loci identified unusual STAT5 binding sites compared to conventional STAT5 responsive elements. Some of the STAT5 targets identified are upregulated in several human cancers, suggesting that they might represent potential oncogenes in STAT5-associated malignancies. Keywords: siRNA-mediated knock-down
Project description:Overexpression of STAT5B_N642H mutant results in the ligand-independent activation of STAT5 signaling and STAT5 transcriptional activity, without affecting MAPK-ERK or PI3K-AKT signalling pathways. Overexpression of wild type (WT) STAT5B did not activate STAT5 signaling . Treatment with prednisolone boosts the expression of STAT5_N642H regulated genes, whereas NR3C1 can bind at gene loci of STAT5 regulated genes. Despite the steroid-enhanced upregulation of anti-apoptotic targets, the mutant cell line remaind sensitive to steroid treatment. We studied potential co-regulation and co-binding of NR3C1 and STAT5B in STAT5B_N642H and STAT5B_WT overexpressing cells, treated and untreated with prednisolone.
Project description:This SuperSeries is composed of the SubSeries listed below. This SuperSeries is part of a study entitled 'Constitutively active STAT5b feminizes mouse liver gene expression', where delivery of constitutively active STAT5 (STAT5CA) to male mouse liver was shown to induce widespread feminization of the liver, with extensive induction of female-biased genes and repression of male-biased genes, largely mimicking results obtained when male mice are given GH as a continuous infusion. Many of the STAT5CA-responding genes were associated with nearby (< 50 kb) sites of STAT5 binding to liver chromatin, supporting the proposed direct role of persistently active STAT5 in continuous GH-induced liver feminization. The feminizing effects of STAT5CA were dose-dependent; moreover, at higher levels, STAT5CA overexpression resulted in some histopathology, including hepatocyte hyperplasia, and increased karyomegaly and multinuclear hepatocytes. Together, these findings establish that the persistent activation of STAT5 by GH that characterizes female liver is by itself sufficient to account for the sex-dependent expression of a majority of hepatic sex-biased genes.