Project description:The signal transducer and activator of transcription 5 (STAT5) is an attractive therapeutic target but successful targeting of STAT5 has proved to be difficult. We report herein the development of AK-2292 as a first, potent and selective small-molecule degrader of both STAT5A and STAT5B isoforms. AK-2292 induces degradation of STAT5A/B proteins with an outstanding selectivity over all other STAT proteins and >6,000 non-STAT proteins, leading to selective inhibition of STAT5 activity in cells. AK-2292 effectively induces STAT5 depletion in normal mouse tissues and human chronic myeloid leukemia (CML) xenograft tissues and achieves tumor regression in two CML xenograft mouse models at well-tolerated dose-schedules. AK-2292 is not only a powerful research tool with which to investigate the biology of STAT5 and therapeutic potential of selective STAT5 protein depletion and inhibition in vitro and in vivo, but also a promising lead compound toward ultimate development of a STAT5-targeted therapy.
Project description:We have developed AK2292 as a first, potent and selective small-molecule degrader of both STAT5A and STAT5B isoforms. To investigate the effect of STAT5A/STAT5B depletion on the transcriptome, we treated KU812 and NCO2 cells with AK2292 at 1 μM for 8 h and performed RNA-seq analysis. As a control, we treated KU812 and NCO2 cells with AK2292Me at 5 μM for 24 h for RNA-seq analysis. RNA-seq analysis revealed that AK2292 downregulates the transcriptome associated with STAT5A and STAT5B.
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:RNA-Seq of immortalized Stat5a-/-, Stat5b-/-, and wildtype BCR/ABLp185+ cell lines was used to identify STAT5A and STAT5B specific target genes.
Project description:Stat5a and Stat5b proteins are highly homologous with greater than 90% amino acid identity and share binding to the palindromic Stat5 consensus sequence, TTCNNNGAA, but individual roles of each transcription factor in breast cancer have not been thoroughly evaluated. To determine the degree of similarity between transcripts modulated by Stat5a and Stat5b proteins in human breast cancer, we utilized genome-wide transcript profiling to identify genes regulated specifically by Stat5a or Stat5b in response to prolactin. Stat5a or Stat5b was transiently overexpressed using adenoviral gene delivery in MCF7 breast cancer cells followed 16 hr serum starvation and a brief 4 hr exposure to 10nM human prolactin to identify immediate-early transcripts modulated by each transcription factor. Basal activation of Stat5a or Stat5b was not present in cells not stimulated with prolactin. mRNA from each condition was harvested and validated using the Agilent bioanalyzer. cDNA was generated and genome-wide transcript profiling was performed in triplicate using the Affymetrix HuGene 1.0 ST array.
Project description:Stat5a and Stat5b proteins are highly homologous with greater than 90% amino acid identity and share binding to the palindromic Stat5 consensus sequence, TTCNNNGAA, but individual roles of each transcription factor in breast cancer have not been thoroughly evaluated. To determine the degree of similarity between transcripts modulated by Stat5a and Stat5b proteins in human breast cancer, we utilized genome-wide transcript profiling to identify genes regulated specifically by Stat5a or Stat5b in response to prolactin.
Project description:Two highly conserved transcription factors STAT5A and STAT5B play an identical role in the intracellular signaling pathway upon cytokine stimulation, while gene deletion experiments have revealed separable and overlapping functions of STAT5. This questions whether the phenotypic differences in the organ development observed in the individual knockout mice result from isoform-specific functions or quantitative differences in the expression levels of each STAT5 isoform among tissues. To elucidate the redundancy and isoform-specificity of STAT5 for development at molecular levels, mice carrying only a single allele of either Stat5a or Stat5b were generated. Both of these mice overcame the lethal anemia observed in Stat5ab-null mice, indicating that development of erythroid cell lineage was totally dependent on the dosage of STAT5. The blocked progression of B cell lineage at the pre-pro B cell stage in Stat5ab-/- mice was rescued in the presence of a single allele of either Stat5a or Stat5b, while the number of total B220+ cells in bone marrow was smaller in Stat5abnull/Stat5b- mice than Stat5abnull/Stat5a- mice. The paucity of alveolar progenitor cells in the Stat5ab-null mammary epithelium was rescued by a single allele of either Stat5a but not Stat5b, suggesting cell-type dependent isoform-specific function. Genome-wide gene expression analyses revealed that different steps of cell lineage progression require different gene sets which expression requires the different isoform of STAT5 in a dose-dependent manner in the mammary epithelium. Taken together, this study demonstrates that dose-dependent isoform specificity of STAT5A and STAT5B controls progression and differentiation of each cell lineage. Six days after observation of a plug, mammary tissues from three of each Stat5a-/- mice, Stat5ab+/null mice, Stat5abnull/Stat5b- and Stat5abnull/Stat5a- mice were collected, frozen in liquid nitrogen, and stored at -70 °C
Project description:Leukemic stem cells (LSCs) can acquire non-mutational resistance following drug treatment leading to therapeutic failure and relapse. However, oncogene-independent mechanisms of drug persistence in LSCs are incompletely understood, which is the primary focus of this study. We integrated proteomics, transcriptomics, and metabolomics to determine the contribution of STAT3 in promoting metabolic changes in tyrosine kinase inhibitor (TKI) persistent chronic myeloid leukemia (CML) cells. Proteomic and transcriptional differences in TKI persistent CML cells revealed BCR-ABL-independent STAT3 activation in these cells. While knockout of STAT3 inhibited the CML cells from developing drug-persistence, inhibition of STAT3 using a small molecule inhibitor sensitized the persistent CML cells to TKI treatment. Interestingly, given the role of phosphorylated STAT3 as a transcription factor, it localized uniquely to genes regulating metabolic pathways in the TKI-persistent CML stem and progenitor cells. Subsequently, we observed that STAT3 dysregulated mitochondrial metabolism forcing the TKI-persistent CML cells to depend on glycolysis, unlike TKI-sensitive CML cells, which are more reliant on oxidative phosphorylation. Finally, targeting pyruvate kinase M2, a rate-limiting glycolytic enzyme, specifically eradicated the TKI-persistent CML cells. By exploring the role of STAT3 in altering metabolism, we provide critical insight into identifying potential therapeutic targets for eliminating TKI-persistent LSCs.
Project description:Leukemic stem cells (LSCs) can acquire non-mutational resistance following drug treatment leading to therapeutic failure and relapse. However, oncogene-independent mechanisms of drug persistence in LSCs are incompletely understood, which is the primary focus of this study. We integrated proteomics, transcriptomics, and metabolomics to determine the contribution of STAT3 in promoting metabolic changes in tyrosine kinase inhibitor (TKI) persistent chronic myeloid leukemia (CML) cells. Proteomic and transcriptional differences in TKI persistent CML cells revealed BCR-ABL-independent STAT3 activation in these cells. While knockout of STAT3 inhibited the CML cells from developing drug-persistence, inhibition of STAT3 using a small molecule inhibitor sensitized the persistent CML cells to TKI treatment. Interestingly, given the role of phosphorylated STAT3 as a transcription factor, it localized uniquely to genes regulating metabolic pathways in the TKI-persistent CML stem and progenitor cells. Subsequently, we observed that STAT3 dysregulated mitochondrial metabolism forcing the TKI-persistent CML cells to depend on glycolysis, unlike TKI-sensitive CML cells, which are more reliant on oxidative phosphorylation. Finally, targeting pyruvate kinase M2, a rate-limiting glycolytic enzyme, specifically eradicated the TKI-persistent CML cells. By exploring the role of STAT3 in altering metabolism, we provide critical insight into identifying potential therapeutic targets for eliminating TKI-persistent LSCs.
Project description:Leukemic stem cells (LSCs) can acquire non-mutational resistance following drug treatment leading to therapeutic failure and relapse. However, oncogene-independent mechanisms of drug persistence in LSCs are incompletely understood, which is the primary focus of this study. We integrated proteomics, transcriptomics, and metabolomics to determine the contribution of STAT3 in promoting metabolic changes in tyrosine kinase inhibitor (TKI) persistent chronic myeloid leukemia (CML) cells. Proteomic and transcriptional differences in TKI persistent CML cells revealed BCR-ABL-independent STAT3 activation in these cells. While knockout of STAT3 inhibited the CML cells from developing drug-persistence, inhibition of STAT3 using a small molecule inhibitor sensitized the persistent CML cells to TKI treatment. Interestingly, given the role of phosphorylated STAT3 as a transcription factor, it localized uniquely to genes regulating metabolic pathways in the TKI-persistent CML stem and progenitor cells. Subsequently, we observed that STAT3 dysregulated mitochondrial metabolism forcing the TKI-persistent CML cells to depend on glycolysis, unlike TKI-sensitive CML cells, which are more reliant on oxidative phosphorylation. Finally, targeting pyruvate kinase M2, a rate-limiting glycolytic enzyme, specifically eradicated the TKI-persistent CML cells. By exploring the role of STAT3 in altering metabolism, we provide critical insight into identifying potential therapeutic targets for eliminating TKI-persistent LSCs.