Abstract 268: Ryanodine receptor-1 upregulation alters organellar calcium signaling, modulates gene expression and contributes to ovarian cancer development

Abstract Ca2+ signaling plays crucial roles in cancer development through Ca2+-dependent regulation of gene transcription. However, specific changes of Ca2+ signaling in HGSOC are unclear. Analysis of RNAseq data from TCGA and GEO database and our patient samples identified ryanodine receptor 1 (RYR1) over-expression was associated with poor survival of HGSOC patients. RYR1 expression was also markedly higher in several HGSOC cell lines compared to normal human control cells. To examine Ca2+ signaling in HGSOC cells, cytosolic, nucleoplasmic, and mitochondrial [Ca2+] were monitored by confocal imaging of Ca2+ fluorescence dyes and organelle specific Ca2+ biosenors. Resting cytosolic [Ca2+] and [Ca2+]nucleus was significantly elevated. Ca2+ signals triggered by the RYR-agonist 4-chloro-m-cresol (4-cmc) in cytosol, nucleus, and mitochondria were significantly higher in OVCA432 cells compared to the control HOSE cells. The elevated resting [Ca2+] and the 4-cmc-induced Ca2+ signals in various intracellular compartments were reduced to the control level by RYR1-shRNA in OVCA432 cells. Gene Set Enrichment Analysis of RNAseq data revealed that RYR1 silencing suppressed gene sets related to mitochondrial proteins, mitochondrial membrane potential, fatty acid metabolism and oxidoreductase activity, as well as activated gene sets related to histone 4 lysine acetyltransferase, H2A ubiquitination and protein localization to chromatin, suggesting RYR1 in HGSOC cells plays important roles in modulating mitochondrial functions and epigenetic regulation of gene expression. Furthermore, shRNA knockdown or inhibition of RYR1 with the RYR1 blocker dantrolene suppressed HGSOC proliferation and migration, and significant reduced OC tumor evaluated by bioluminescence and tumor weight in OVCA432 cells injected athymic nude mice These observations are the first direct evidence that RYR1 alters cytosolic, nucleoplasmic and mitochondrial Ca2+ signaling in HGSOC cells, and these changes may contribute to the malignant phenotype for HGSOC development. Citation Format: Chi-Lam Au-Yeung, Kay-Pong Yip, Wan-Yee Tang, Samuel C. Mok, James S.K. Sham. Ryanodine receptor-1 upregulation alters organellar calcium signaling, modulates gene expression and contributes to ovarian cancer development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 268.