Abstract 6490: Pt1a and sorafenib combination treatment exerts synergistic anti-hepatocellular carcinoma effect through RNA m6A methylation modification

Abstract Hepatocellular carcinoma (HCC) is the most common type of liver cancer and has a poor prognosis. The survival benefits of sorafenib in patients with advanced HCC are modest owing to acquired resistance. Accumulating evidence has demonstrated that cancer stemness is an important cause of drug resistance and the root cause of tumor recurrence. PtII (CNN) (NHC2Bu) PF6 (Pt1a) is a newly developed platinum-based drug containing N-heterocyclic carbene with proven anticancer properties against a range of tumor types. However, its role in targeting cancer stemness and its ability to sensitize cancer cells to overcome molecular-targeted therapy drug resistance in HCC remains elusive. Herein, we demonstrate the synergistic inhibitory effect of sorafenib and Pt1a combination treatment on HCC through RNA m6A methylation modification. In cultured HCC cells and patient-derived organoids, the drug combination synergistically reduced the cell viability and promoted cell apoptosis compared to single-drug treatment. Combination treatment also attenuated self-renewal, as evidenced by a marked decrease in tumor-initiating cancer cell frequency, as measured by limiting dilution spheroid formation assay. These findings were further validated in HCC patient-derived xenograft mouse models and a mouse HCC model induced by hydrodynamic tail vein delivery of NRAS+AKT coactivation plasmids. Notably, the combination treatment with sorafenib and Pt1a, but not a single treatment, led to a significant reduction in tumor burden. The combination treatment was also effective in decreasing tumor-initiating cell frequency, as measured by subjecting the harvested tumor cells for limiting dilution spheroid formation assay ex vivo. Mechanistically, integrative RNA-sequencing and thermal proteome profiling analyses both indicated the enrichment of m6A-related pathways in combination drug treatment. An increased global m6A level upon combination treatment was validated using m6A dot blotting, confirming that the synergistic effect may be mediated by the elevated global m6A level in HCC cells. Collectively, our study demonstrated that Pt1a and sorafenib combination treatment synergistically inhibited the viability and stemness of HCC cells by increasing global RNA m6A level. These findings supported the potential of Pt1a as a therapeutic option for HCC and overcoming sorafenib drug resistance. Ongoing studies are focused on identifying m6A regulators and downstream targets involved in combination treatment. Citation Format: Yinjia Huang, Yalu Cui, Ianto Bosheng Huang, Yanyan Wang, Yang Xuan, Pui Ki Wan, Chun Nam Lok, Chi Ming Che, Stephanie Ma. Pt1a and sorafenib combination treatment exerts synergistic anti-hepatocellular carcinoma effect through RNA m6A methylation modification abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 6490.