Abstract 7040: Mutations in cytoskeleton genes SPTAN1/SPTBN1 serve as novel predictive markers for immunotherapy against bladder cancer

Abstract

Abstract Cancer progression is often driven by somatic mutations. Despite several well-known driver mutations, more evidence has shown that genetic alterations in cytoskeleton organization enhance tumor aggressiveness and promote cancer progression, suggesting their roles as potential drivers. In this study, pan-cancer genetic analyses by using TCGA cohorts, more frequent mutation events were found in cytoskeleton-related genes as compared to total annotated genes, especially in cancers derived from hollow organs. High-dimensional analysis of molecular alterations in cancer (HD-MAC) suggested gene mutations in SPTAN1 and its partner SPTBN1 as potential prognostic biomarkers for clinical outcomes of patients with bladder cancer. Gene knockdown in either SPTAN1 or SPTBN1, mimicking silencing mutations in cancer tissues, caused cell morphology changes, DNA breaks, and alternations in cytokine profiles via activating cGAS-STING mediated interferon signaling. Xenograft tumor models also indicate accelerated tumor growth in SPTAN1- or SPTBN1-silenced cells, suggesting a more advanced cancer type. Based on immune staining in both human and mouse samples, increased CD8+ T cell infiltration was in tumor lesions with mutations or truncations in SPTAN1/SPTBN1 genes. In addition, several known substitution mutations were found as potent neo-antigens based on MHC II binding prediction, which could be utilized as targets for immune checkpoint therapy. This study provides a novel insight into how the cytoskeleton can contribute to cancer progression and find out predictive biological indicators with therapeutic values. Citation Format: Brian Yu-Ting Kuo. Mutations in cytoskeleton genes SPTAN1/SPTBN1 serve as novel predictive markers for immunotherapy against bladder cancer [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 7040.