Abstract 1357: miR-16-5p and miR-124-3p block the immunosuppressive phenotype of GBM cells in vitro

Abstract A hallmark of GBM is its highly-immunosuppressive tumor microenvironment (TME). GBM stem-like cells (GSCs) can evade immune surveillance to allow for continued tumor growth and propagation. GSCs regulate the immune TME through recruitment and production of immunosuppressive cells and factors via tumor cell-intrinsic mechanisms. Blocking these cell-intrinsic immunosuppressive mechanisms is widely viewed as a way to enhance the effects of current immune therapies. We recently showed that TGFβ type II receptor (TGFBR2) promotes a mesenchymal transition in GBM cells characterized by high expression levels of immunosuppressive genes NT5E (CD73), ENTPD1 (CD73), LGALS1 (galectin-1), CD274 (PD-L1), PDCD1LG2 (PD-L2), and TGFB1. miRNA network analysis identified miR-16-5p and miR-124-3p as high-confidence candidates to block the expression of these immunosuppressive signaling axis in GBM cells. Transgenic miR-16-5p and miR-124-3p simultaneously reduced expression of CD274, ENTPD1, NT5E, TGFB1, and LGALS1 and increased tumor cell killing of PBMC-derived CD4+ and CD8+ T cells. We also measured an increase in drivers of the CD8+ effector state and a decrease in expression of exhaustion marker PD1 in PBMC-derived CD8+ T cells. In addition to the effects on CD4+ and CD8+ T cell activation and function, miRNA-mediated knock-down of this immunosuppressive gene signature in tumor cells also resulted in a decrease in CD206 expression and reduced release of anti-inflammatory chemokines in THP1 cells. These findings demonstrate that miRNA-based gene inhibition can block cell-intrinsic immunosuppressive pathways to enhance anti-tumor immune cell function in vitro and predicts that delivering these miRNAs using advanced nanocarriers will cooperate with current immunotherapies in vivo. Citation Format: TC Taylor, Amanda Johnson, Harmon Khela, Jack Korleski, Sophie Sall, Bachchu Lal, Karen Smith-Connor, Hernando Lopez-Bertoni. miR-16-5p and miR-124-3p block the immunosuppressive phenotype of GBM cells in vitro. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1357.