Ryanodine Receptor-1 Upregulation Alters Cytosolic and Organellar Calcium Signaling, Modulates Gene Expression and Contributes to Ovarian Cancer Cell Phenotypes

Ovarian cancer (OC) is the most lethal gynecologic malignancy worldwide accounting for 22,000 new cases and >16,000 deaths each year in the United States. High grade serous ovarian cancer (HGSOC) is responsive to initial chemotherapy using combination platinum and taxane chemotherapy following debulking surgery. However, 75%–80% of cases recur within 12–24 months, and most patients died of progressive chemotherapy-resistant disease. Hence, identifying new therapeutic targets is crucial for developing treatments for prolonging OC patient survival. Ca 2+ signaling plays crucial roles in cancer development through Ca 2+ -dependent regulation of gene transcription. However, specific changes of Ca 2+ 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 Ca 2+ signaling in HGSOC cells, cytosolic, nucleoplasmic, and mitochondrial [Ca 2+ ] were monitored by confocal imaging of Ca 2+ fluorescence dyes and organelle specific Ca 2+ biosenors. Resting cytosolic [Ca 2+ ] and [Ca 2+ ] nucleus was significantly elevated. Ca 2+ 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 [Ca 2+ ] and the 4-cmc-induced Ca 2+ 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. Further analysis showed that PGC1A and TFAM genes in OVCA432 are epigenetically modified in a RYR1-dependent manner. Moreover, 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 Ca 2+ signaling in HGSOC cells, and these changes may contribute to the malignant phenotype for HGSOC development. This work is supported by DoD grant W81XWH-20-OCRP-IIRA This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.