Abstract 3221: Targeting ARID1A-mutated gastric cancer cells with synthetic lethal approaches

Abstract AT-rich interaction domain 1A (ARID1A) functions as a tumor suppressor gene, and its loss or inactivation is a common occurrence in various human malignancies, including around 30% of gastric cancers (GC). This study aimed to identify potential therapeutic targets for GC cells with ARID1A deficiency. After robust screening from a chemical library consisting of 551 diverse protein kinase inhibitors, we identified the AKT inhibitor AZD5363 as being the most potent lead compound in inhibiting viability of ARID1A−/− cells. A synthetic lethality between loss of ARID1A expression and AKT inhibition by AZD5363 was validated in both GC cell model system and xenograft model. Mechanistically, AZD5363 treatment induced pyroptotic cell death in ARID1A-deficient GC cells through activation of the caspase-3/GSDME pathway. Furthermore, ARID1A occupied the AKT gene promoter and regulated its transcription negatively, thus the GC cells deficient in ARID1A showed increased expression and phosphorylation of AKT. Our study demonstrates a novel synthetic lethality interaction and unique mechanism between ARID1A loss and AKT inhibition, which may provide a therapeutic and mechanistic rationale for targeted therapy on patients with ARID1A-defective GC who are most likely to be beneficial to AZD5363 treatment. Citation Format: Menghan Fang, Youfen Lin, Chaorong Xue, Kaiqin Sheng, Zegeng Guo, Yuting Han, Hanbin Lin, Yuecheng Wu, Stephen B. Howell, Xu Lin, Xinjian Lin. Targeting ARID1A-mutated gastric cancer cells with synthetic lethal approaches [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(6_Suppl):Abstract nr 3221.