Project description:Ovarian carcinoma (OC) is the fifth leading cause of death among women in the United States. Persistent activation of signal transducer and activator of transcription (STAT3) is frequently detected in OC. STAT3 is activated by Janus family kinases (JAK) via cytokine receptors, growth factor receptor and non-growth factor receptor tyrosine kinases. Activation of STAT3 mediates tumor cell proliferation, survival, motility, invasion, and angiogenesis, and recent work demonstrates that STAT3 activation suppresses anti-tumor immune responses and supports tumor-promoting inflammation. We hypothesized that therapeutic targeting of the JAK/STAT3 pathway would inhibit tumor growth by direct effects on OC cells and by inhibition of cells in the tumor microenvironment (TME). To test this, we evaluated the effects of a small molecule JAK inhibitor, AZD1480, on cell viability, apoptosis, proliferation, migration and adhesion of OC cells in vitro. We then evaluated the effects of AZD1480 on in vivo tumor growth and progression, gene expression, tumor-associated matrix metalloproteinase (MMP) activity and immune cell populations in a transgenic mouse model of OC. AZD1480-treatment inhibited STAT3 phosphorylation and DNA binding, and migration and adhesion of cultured OC cells and ovarian tumor growth rate, volume and ascites production in mice. In addition, drug treatment led to altered gene expression, decreased tumor-associated MMP activity, and fewer suppressor T cells in the peritoneal tumor microenvironment of tumor-bearing mice than control mice. Taken together, our results show pharmacological inhibition of the JAK2/STAT3 pathway leads to disruption of functions essential for ovarian tumor growth and progression and represents a promising therapeutic strategy. 8 female C57BL/6JTgMISIIR-TAg mice with ovarian tumors of ~500 mm3 were used. 4 vehicle-treated mice (0.5% hypermellose/0.1%Tween 80);4 drug-treated mice (30 mg/kg AZD1480 in 0.5% hypermellose/0.1%Tween 80).
Project description:Ovarian carcinoma (OC) is the fifth leading cause of death among women in the United States. Persistent activation of signal transducer and activator of transcription (STAT3) is frequently detected in OC. STAT3 is activated by Janus family kinases (JAK) via cytokine receptors, growth factor receptor and non-growth factor receptor tyrosine kinases. Activation of STAT3 mediates tumor cell proliferation, survival, motility, invasion, and angiogenesis, and recent work demonstrates that STAT3 activation suppresses anti-tumor immune responses and supports tumor-promoting inflammation. We hypothesized that therapeutic targeting of the JAK/STAT3 pathway would inhibit tumor growth by direct effects on OC cells and by inhibition of cells in the tumor microenvironment (TME). To test this, we evaluated the effects of a small molecule JAK inhibitor, AZD1480, on cell viability, apoptosis, proliferation, migration and adhesion of OC cells in vitro. We then evaluated the effects of AZD1480 on in vivo tumor growth and progression, gene expression, tumor-associated matrix metalloproteinase (MMP) activity and immune cell populations in a transgenic mouse model of OC. AZD1480-treatment inhibited STAT3 phosphorylation and DNA binding, and migration and adhesion of cultured OC cells and ovarian tumor growth rate, volume and ascites production in mice. In addition, drug treatment led to altered gene expression, decreased tumor-associated MMP activity, and fewer suppressor T cells in the peritoneal tumor microenvironment of tumor-bearing mice than control mice. Taken together, our results show pharmacological inhibition of the JAK2/STAT3 pathway leads to disruption of functions essential for ovarian tumor growth and progression and represents a promising therapeutic strategy.
Project description:Tumor-associated macrophages contribute to tumor progression and therapeutic resistance in breast cancer. Within the tumor microenvironment, tumor-derived factors activate pathways that modulate macrophage function. Using in vitro and in vivo models, we find that tumor-derived factors induce activation of the Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) pathway in macrophages. We also demonstrate that loss of STAT3 in myeloid cells leads to enhanced mammary tumorigenesis. Further studies show that macrophages contribute to resistance of mammary tumors to the JAK/STAT inhibitor ruxolitinib in vivo and that ruxolitinib-treated macrophages produce soluble factors that promote resistance of tumor cells to JAK inhibition in vitro. Finally, we demonstrate that STAT3 deletion and JAK/STAT inhibition in macrophages increases expression of the pro-tumorigenic factor cyclooxygenase-2 (COX-2) and that COX-2 inhibition enhances responsiveness of tumors to ruxolitinib. These findings define a novel mechanism through which macrophages promote therapeutic resistance and highlight the importance of understanding the impact of targeted therapies on the tumor microenvironment.
Project description:To identify downstream targets of Jak/Stat3 pathways without being distracted by differentiation signalings from MEK/ERK pathway, we exploited a engineered B6 cells, which stably stably expressing a chimeric receptor (GRgp-Y118F). The chimeric receptor can induce the phosphorylation of Stat3 by GCSF without activating the MEK/ERK pathway. To mimic the effect of GCSF, the chimeric B6 cells were also treated with LIF plus a selective MEK chemical inhibitor, PD0325901, to induce LIF/Jak/Stat3 but MEK/ERK pathways. mESCs starved in serum free growth medium for 6hrs were treated with GCSF or with LIF plus PD0325901 for 1hr, after which total RNA was extracted for analysis.
Project description:Activating mutations of STAT3 were frequently found in patients with natural killer/T-cell lymphoma (NKTL), suggesting that targeted inhibition of STAT3 is a potential therapeutic option for NKTL patients. Here, we have developed a novel and potent STAT3 inhibitor WB737 that directly binds to the STAT3-SH2 domain with high affinity. WB737 selectively inhibits cell growth of NKTL harbored STAT3 mutations through inducing apoptosis and blocking colony formation. Mechanistically, WB737 inhibits both canonical and non-canonical STAT3 signaling via suppression of STAT3 phosphorylation at Tyr705 and Ser727 sites, respectively. Moreover, the activity of WB737 has a more potent inhibition on STAT3 compared to Sttatic, resulting in a significant anti-tumor effect followed by almost complete tumor regression in a NKTL xenograft model harboring STAT3 activating mutation. Collectively, these findings provide a preclinical proof-of-concept for WB737 as a novel therapeutic strategy for the treatment of NKTL patients with STAT3-activating mutations.
Project description:RNA sequencing was carried out to identify the signaling pathways and hallmarks that change following MEK and/or JAK/STAT3 pathway inhibition.
Project description:PAX2 is one of nine PAX genes that regulate tissue development and cellular differentiation in embryos. PAX2 promotes cell proliferation, oncogenic transformation, cell lineage specification, migration, and survival. In our previous study, we found that PAX2 is highly expressed in low-grade ovarian serous carcinoma, but its expression in clear cell, endometrioid, and mucinous cell ovarian carcinomas have not been studied. More importantly, the functional role of PAX2 in ovarian cancer is not known. Downregulation of PAX2 in PAX2-expressing ovarian cancer cells inhibits cell proliferation and migration. This growth inhibition is due to the upregulation of the tumor suppressor gene G0S2 and subsequent induction of apoptosis. The PAX2 pathway thus represents a potential therapeutic target for PAX2-expressing ovarian carcinomas. Knockdown PAX2 expression in these cell lines was achieved by lentiviral shRNAs targeting the PAX2 gene. PAX2 stable knockdown cells were characterized for cell proliferation, migration, apoptosis, and gene expression profiles.
Project description:Inflammatory breast cancer (IBC) is a difficult-to-treat disease with poor clinical outcomes due to high risk of metastasis and resistance to treatment. We previously described a CD44+CD24-pSTAT3+ cancer cell subpopulation with stem cell-like features in breast cancer that is dependent on JAK/STAT3 signaling. Here we report that CD44+CD24- cells are the most frequent cell-type in IBC and are commonly pSTAT3+. Combination of JAK/STAT3 inhibition with paclitaxel decreased IBC xenograft growth more than either agent alone. We developed and characterized IBC cell lines resistant to paclitaxel and doxorubicin to mimic therapeutic resistance in patients. Multi-omic profiling of parental and resistant cells revealed genes associated with lineage identity and inflammation were enriched in chemotherapy resistant derivatives. Integrated pSTAT3 ChIP-seq and RNA-seq analyses showed pSTAT3 regulates genes related to inflammation and epithelial to mesenchymal transition (EMT) in resistant cells, as well as PDE4A, a cAMP-specific phosphodiesterase. Metabolomic characterization identified elevated cAMP signaling and CREB as a candidate therapeutic target in IBC. We also investigated cellular dynamics and heterogeneity at the single cell level during chemotherapy and acquired resistance by CyTOF and single cell RNA-seq. We identified mechanisms of resistance including a shift from luminal to basal/mesenchymal cell states through selection for rare pre-existing subpopulations or an acquired change. Lastly, we showed that combination treatment with paclitaxel and JAK/STAT3 inhibition prevented the emergence of this more mesenchymal chemo-resistant subpopulation. Our results provide mechanistic rational for combination of chemotherapy with inhibition of JAK/STAT3 signaling as a new more effective therapeutic strategy in IBC.
Project description:PAX2 is one of nine PAX genes that regulate tissue development and cellular differentiation in embryos. PAX2 promotes cell proliferation, oncogenic transformation, cell lineage specification, migration, and survival. In our previous study, we found that PAX2 is highly expressed in low-grade ovarian serous carcinoma, but its expression in clear cell, endometrioid, and mucinous cell ovarian carcinomas have not been studied. More importantly, the functional role of PAX2 in ovarian cancer is not known. Downregulation of PAX2 in PAX2-expressing ovarian cancer cells inhibits cell proliferation and migration. This growth inhibition is due to the upregulation of the tumor suppressor gene G0S2 and subsequent induction of apoptosis. The PAX2 pathway thus represents a potential therapeutic target for PAX2-expressing ovarian carcinomas.