Abstract PR001: Targeting mRNA methyltransferase in RNA-dependent DNA repair in cancer therapy

Abstract

Abstract The treatment of many solid tumors presents significant challenges with chemotherapy, radiation therapy, and the limited effectiveness of immunotherapy. Targeted therapy offers a promising approach, yet the lack of validated targets limits its applicability across the spectrum of solid tumors. Our past studies have revealed that an R-loop and mRNA-dependent DNA repair (RDDR) pathway, induced by damage at the transcribed regions of the genome, contributes to cell survival and drug resistance in cancer cells. This is particularly due to the high levels of transcription and DNA damage in these cells. We identified the RNA methyltransferase TRDMT1 as the primary modifier of mRNA methyl-5-cytosine in the RDDR pathway. Overcoming technical difficulties in monitoring RNA modifications, we developed the first TRDMT1 inhibitor (TRDMT1i) using in-house built cell-based and in vitro assays. We have identified highly potent and specific lead compounds that significantly reduce TRDMT1 activity at nanomolar concentrations. Our current lead TRDMT1 inhibitors meets most of the criteria that are required for optimal lead. Initial assessments involving the screening of normal and cancer cell lines, xenograft models, and patient specimens indicate that TRDMT1i sensitizes tumors with genomic instability when used as monotherapy. We aim to develop TRDMT1i as an investigational new drug (IND) for future clinical trials, initially targeting ovarian cancer as a monotherapy or in combination therapy for first-line maintenance and systematic therapy. Our goal is to pioneer the discovery of the RDDR pathway, leading to the development of innovative platforms and next-generation medications to revolutionize the targeting of mRNA modifications in cancer treatment. Citation Format: Li Lan. Targeting mRNA methyltransferase in RNA-dependent DNA repair in cancer therapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr PR001.