Abstract 5009: Inhibition of TGFBR2 signaling re-sensitizes TMZ-resistant glioblastoma cells to therapy

Abstract Glioblastoma (GBM), the most aggressive and lethal form of brain tumors, recurs in 90% of cases and the standard protocol of care—temozolomide (TMZ)—is an ineffective method to combat chemo-resistant GBM. It is therefore imperative that we identify, develop, and design novel therapeutics to effectively combat recurrent GBM (rGBM). Multi-potent stem-like cell subpopulations within GBM (also referred to as glioma stem cells or GSCs) play important roles in tumor propagation, therapeutic resistance, and recurrence following treatment. Understanding the molecular mechanisms that drive resistance in GSCs can lead to novel therapeutic approaches for rGBM. Bioinformatics analyses of transcriptome data sets from rGBM clinical specimens identified transforming growth factor-beta receptor type 2 (TGFBR2) as a putative driver of resistance and recurrence in GBM. We show that TMZ-resistant cells become more stem-like concurrent with higher expression of TGFBR2 protein and mRNA. Importantly, shRNA-mediated inhibition of TGFBR2 decreases proliferation of TMZ-resistant cells and enhances the effects of TMZ. We hypothesize that by developing targeted therapeutics to reduce TGFBR2 expression we will inhibit the growth capacity and/or re-sensitize rGBM cells to ionizing radiation (IR) or TMZ treatment by simultaneously targeting multiple putative oncogenes implicated in the induction of stem-like resistant GBM cell subsets. Future directions include inhibiting TGFBR2 signaling in clinical specimens derived from rGBM patients using two translatable approaches: (1) ITD1, a small molecule TGFBR2 inhibitor predicted to cross the blood-brain-barrier and (2) microRNAs to target multiple TGFBR2 target genes up-regulated in rGBM. Citation Format: Maya K. Johnson, Jack Korleski, Amanda Johnson, Sophie Sall, John Laterra, Hernando Lopez-Bertoni. Inhibition of TGFBR2 signaling re-sensitizes TMZ-resistant glioblastoma cells to therapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5009.