128 research outputs found
MiR-17-92 Cluster Regulation in Differentiated T-cells
No full textData from our group and others have demonstrated that tumor-derived factors directly skew T-cell differentiation from an effective tumor fighting Th1 state to a less effective Th2 state, allowing for tumor growth. Why the Th1 response is more effective is largely still unknown. The recently discovered microRNAs (miRNAs) are a large family of small regulatory RNAs that control diverse aspects of cell functions such as cell proliferation, apoptosis, development, differentiation and immune regulation. We thereby sought to examine miRNAs differentially expressed in Th1 and Th2 cells in an effort to better understand the enhanced ability of Th1 cells in tumor immunity. MicroRNA microarray analyses revealed that the miR-17-92 cluster of microRNAs (miR-17-92) is consistently over-expressed in murine Th1 cells compared to Th2 cells. Quantitative RT-PCR confirmed that the miR-17-92 cluster expression was consistently higher in Th1 cells than Th2 cells. Furthermore, disruption of IL-4 signaling through either IL-4 neutralizing antibody or knockout of STAT6 reversed the miR-17-92 cluster suppression in Th2 cells. MiR-17-92 expression correlated with differential proliferation capacity as Th1 cells proliferated at higher levels than Th2 cells, dependent on IL-4 and STAT6. Th1 cells consistently expressed lower levels of anti-proliferative transcription factors E2F1 and E2F2, which are the known targets of miR-17-92. Collectively, our data suggests that the Th2 skewing tumor microenvironment can induce the down-regulation of miR-17-92 expression in CD4+T cells, thereby diminishing the effective proliferation of tumor-specific T cells and tumor destruction. This has significant public health relevance as we propose that therapy targeting miR-17-92 cluster may provide enhanced T-cell function and prevent tumor growth
Novel mechanisms of cytokine signaling on T-cell and MDSC function in glioma development
No full textMalignant gliomas are the most common primary brain tumors with dismal prognosis. A growing line of evidence supports significant roles of immunosurveillance for prevention and regulation of cancer development. For example, tumor infiltrating T-cells are capable of killing tumor cells and are a positive prognostic factor for cancer patients. T-cell immune responses are classified into distinct effector cell types, type-1 or type-2, based on their cytokine-secreting profiles. We have demonstrated that tumor-specific type-1 T-cells, but not type-2 T-cells, can efficiently traffic into CNS tumor sites and mediate effective therapeutic efficacy via a type-1 chemokine CXCL10 and an integrin receptor VLA-4. Despite the importance of the type-1 T cell response, cancers, including GBMs, secrete numerous type-2 cytokines that promote tumor proliferation and immune escape. The hallmark cytokines of type-1 and type-2 immune responses are IFNs and IL-4, respectively. We therefore sought to better understand the role of IL-4 and IFN signaling in gliomas. We herein demonstrate that the miR-17-92 cluster is down-regulated in T-cells in both human and mouse tumors, dependent on IL-4R signaling. Further, ectopic expression of miR-17-92 cluster in T-cells resulted in enhanced IFN-γ and IL-2 production and resistance to activation induced cell death (AICD) (Aim 1). We next examined IL-4Rα on immunosuppressive myeloid derived suppressor cells (MDSCs). Interestingly we found that IL-4Rα was up-regulated on human and mouse glioma infiltrating, but not peripheral, MDSCs. Additionally, IL-4Rα expression promoted arginase activity, T-cell suppressing abilities and glioma growth (Aim 2).
As type I IFNs are important for anti-glioma type-1 immunity, we further examined how type I IFNs impact glioma patient prognosis. As there are multiple type I IFNs, our collaborators assisted us to identify potentially important genes by single nucleotide polymorphism (SNP) analysis. We found that IFN-pathway genes IFN- alpha receptor-1 (IFNAR1) and the IFN-alpha-8 (IFNA8) promoter both had SNPs associated with glioma prognosis. By luciferase assay and electrophoretic mobility shift assay (EMSA) we demonstrated that the A-allele, which is associated with better glioma patient survival, but not the C-allele of rs12553612 in the promoter region of IFNA8 allows for OCT-1 binding and activity of the IFNA8 promoter (Aim 3).
Overall, our data suggests that type-2 promoting has a dual role in suppressing glioma immunity through decreased T-cell functioning and enhanced MDSC function. Type-2 promoted suppression of glioma immunity can thus lead to better glioma patient prognosis, a significant public health achievement
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Statins and PDGFRA Inhibition: A Synergistic Strategy Against Diffuse Midline Glioma
No full textDiffuse midline glioma (DMG) is a fatal pediatric brain tumor with limited treatment options. While PDGFRA inhibitors, like avapritinib, have shown some promise in the clinic, DMGs have been shown to develop resistance to treatment through metabolic adaptations, including increased fatty acid synthesis and oxidative phosphorylation (OXPHOS). This study explores the metabolic basis of DMG treatment resistance to avapritinib and seeks to identify novel drugs that could synergize with avapritinib to provide a durable treatment effect. We demonstrate that atorvastatin synergizes with avapritinib, enhancing cytotoxicity in DMG cells by disrupting lipid metabolism, subsequently leading to increased apoptosis. Furthermore, we reveal that DMG cells treated with long-term avapritinib, called avapritinib-persister cells, exhibit a heightened dependency on OXPHOS and are subsequently more susceptible to statin therapy. Our findings highlight that metabolic reprogramming is a key driver of DMG treatment escape and supports the further consideration of statins as potential metabolic inhibitors when treating DMG with PDGFRA-targeted therapy. Given their established safety and widespread usage, repurposing statins in combination therapy for DMG warrants further preclinical investigation to determine if this approach improves outcomes for DMG patients.Graduate Educatio
ONO-AE3-208 inhibits myeloid derived suppressor cells and glioma growth
No full textMyeloid Derived Suppressor Cells (MDSCs) heavily infiltrate in a variety of solid tumors and suppress anti-tumor T-cell activity. Our recent studies have demonstrated the ability of monocytic, Ly6C+ MDSCs to promote glioma growth through the activation of cyclooxygenase (COX)-2 pathway, which is responsible for prostaglandin-synthesis. ONO-AE3-208 is an antagonist of the prostaglandin E (EP)-4 receptor, which is an important positive feedback regulator of the COX-2 pathway. We thus examined the ability of ONO-AE3-208 to suppress MDSC activity in gliomas. ONO-AE3-208 treatment in mice bearing established GL261-quad glioma in the brain resulted in complete and persistent rejection of the tumors. Flow cytometric analysis revealed that gliomas in the ONO-AE3-208-treated mice were infiltrated by fewer numbers of Ly6C+ MDSCs compared with non-treated animals. We subsequently isolated glioma-infiltrating Ly6C+ MDSCs by flow-sorting to address their functions. RT-PCR analysis revealed that the Ly6C+ MDSCs derived from ONO-AE3-208 treated mice expressed lower levels of the Arg1 and Cox2 expression compared to control animals. Consistently, brain infiltrating leukocytes in ONO-AE3-208 treated tumor-bearing mice demonstrated enhanced IFN-g expression compared with control mice, suggestive of enhanced T-cell activity. Importantly, ONO-AE3-208 inhibited glioma growth and promoted immune activity in 2 additional murine glioma models: the Sleeping Beauty de novo glioma model and the SB28 glioma cell line model. Our data demonstrate that ONO-AE3-208 may be useful in the treatment of glioma patients to suppress Ly6C+ MDSCs and promote anti-tumor immunity
Transgene-derived overexpression of miR-17-92 in CD8+ T-cells confers enhanced cytotoxic activity
No full textMicroRNAs (miRs) play important roles in regulation of a variety of cell functions, including immune responses. We have previously demonstrated that miR-17-92 expression in T-cells enhances Th1 phenotype and provides a long-term protection against glioblastoma when co-expressed as a transgene in T-cells along with a chimeric antigen receptor. To further elucidate the function of miR-17-92 in tumor antigen-specific CD8(+) T-cells, we generated transgenic (Tg) mice in which CD8(+) T-cells overexpress transgene-derived miR-17-92 under the lck promoter as well as T-cell receptor specific for human gp10025-33 (Pmel-1) (miR-17-92/Pmel-Tg). CD8(+) T-cells from miR-17-92/Pmel-Tg mice demonstrated enhanced interferon (IFN)-γ production and cytotoxicity in response to the cognate antigen compared with those from control Pmel-Tg mice without the transgene for miR-17-92. In addition, miR-17-92/Pmel-Tg mouse-derived CD8(+)CD44(+) T-cells demonstrated increased frequencies of cells with memory phenotypes and IFN-γ production. We also found that miR-17-92/Pmel-Tg-derived CD8(+) T-cells expressed decreased levels of transforming growth factor (TGF)-β type II receptor (TGFBR2) on their surface, thereby resisting against suppressive effects of TGF-β1. Our findings suggest that engineering of tumor antigen-specific CD8(+) T-cells to express miR-17-92 may improve the potency of cancer immunotherapy
Transgene-derived overexpression of miR-17-92 in CD8+ T-cells confers enhanced cytotoxic activity
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Abstract 4786: MiR-17-92 expression in differentiated T cells - Implications for cancer immunotherapy
No full textAbstract
As type-1 T cells have been shown to mediate effective anti-tumor immune response, we sought to identify microRNA (miRs) differentially regulated between type-1 and type-2 T cells, and determine how the expression of such miRs are regulated. We performed miR microarray analyses on in vitro differentiated murine T helper type-1 (Th1) and T helper type-2 (Th2) cells to identify differentially expressed miRs. We used RT-PCR to confirm the differential expression levels. WST-1, ELISA, and flow cytometry were used to evaluate the survival, function and phenotype of cells, respectively. Lastly, we employed mice transgenic for the identified miRs to determine the biological impact of the miR expression in T cells. Our miR microarray analyses revealed that the miR-17-92 cluster is one of the most significantly over-expressed miR in murine Th1 cells compared with Th2 cells. RT-PCR confirmed that the miR-17-92 cluster expression was consistently higher in Th1 cells than Th2 cells. Disruption of the IL-4 signaling through either IL-4 neutralizing antibody or knockout of signal transducer and activator of transcription (STAT)6 reversed the miR-17-92 cluster suppression in Th2 cells. Furthermore, T cells from tumor bearing mice and glioma patients had decreased levels of miR-17-92 compared with cells from non-tumor bearing counterparts. CD4+ T cells derived from miR-17-92 transgenic mice demonstrated superior type-1 phenotype with increased IFN-γ production and very late antigen (VLA)-4 expression when compared with counterparts derived from wild type mice. Finally Jurkat T cells ectopically expressing increased levels of miR-17-92 cluster members demonstrated increased IL-2 production and resistance to activation-induced cell death (AICD). Collectively, our data suggest that the type-2-skewing tumor microenvironment can induce the down-regulation of miR-17-92 expression in T cells, thereby diminishing the persistence of tumor-specific T cells and tumor destruction. Genetic engineering of T cells to express miR-17-92 may prove to be a promising approach for cancer immunotherapy.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4786.</jats:p
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