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Abstract There are two distinct functional isoforms of Exchange proteins directly activated by cAMP (EPACs), EPAC1 and EPAC2, which exhibit fundamental distinctions in structure, expression patterns, signaling specificity, and subcellular localization. This diversity suggests that EPAC1 and EPAC2 can operate independently, synergistically, or antagonistically, contributing to the wide range of reported functions and impacts in different cancers and studies. We compared the function of EPAC1 and EPAC2 in ovarian cancer using in vitro and in vivo models and further explored the underlying mechanism in the regulation of metabolism reprogramming. Selective inhibition of EPAC1 and EPAC2 markedly reduced proliferation in ovarian cancer cell lines, leading to cell death and cycle arrest. RNA-seq analysis indicated different downstream signaling pathways triggered by EPAC1 and EPAC2, with EPAC2 specifically linked to functions in energy metabolism. Treatment with an antagonist or knockdown of EPAC2 resulted in attenuation of both glycolysis and oxidative phosphorylation (OXPHOS), while EPAC1 did not induce such effects. Furthermore, inhibition of EPAC2 induced mitochondrial dysfunction, manifested by reduced ATP production, decreased mitochondrial membrane potential, and increased burden of reactive oxygen species (ROS). Our data also revealed that EPAC2 governs the MAPK pathway and mediates the mitochondrial unfolded protein response (UPRmt) in ovarian cancer cells. By delineating the distinctions between EPAC1 and EPAC2 within ovarian cancer cells, this project revised the prevailing understanding of EPACs and suggests the potential for precise targeting of EPAC isoforms as a viable strategy in cancer therapy. Citation Format: Zhengyin Gao, Wanjun Yuan, Leo T. O. Lee. Different roles of EPAC1 and EPAC2 in ovarian cancer: Implications for precision targeting in cancer therapy 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 3075.
Gao et al. (Fri,) studied this question.