Abstract 2839: The functional role of tumor suppressor WW domain-containing oxidoreductase in maintaining genome integrity

The induction of DNA damage response (DDR) to ensure accurate duplication of genetic information during DNA replication is crucial for maintaining genome integrity. Cellular senescence is a DDR mechanism that prevents the proliferation of cells with deleterious DNA damage to avoid mitotic anomalies and inheritance of the damage over cell generations. A decreased ability of the cells to undergo senescence has been suggested to be associated with cancer development. Using Wwox knockout models, we determined that Wwox knockout mouse embryonic fibroblasts (MEFs) failed to undergo replication stress-induced cellular senescence after multiple passages in culture. Importantly, accelerated cell cycle progression and increased apoptosis were detected in Wwox knockout MEFs at late passages. Increased γH2AX-positive cells and microsatellite instability were examined in late-passage Wwox knockout MEFs, indicating massive accumulation of DNA damages in these cells. We detected significantly reduced expression of p53 and CDK inhibitors p16INK4A and p21cip1/waf1 in late-passage Wwox knockout MEFs. Inhibition of oxidative stress during en vitro passage culture reversed p16INK4A and p21cip1/waf1 downregulation and induced senescence in Wwox knockout MEFs. Importantly, we demonstrated that WWOX protein expression was upregulated in cells during DNA replication. Significantly enhanced phosphorylation of Chk-1 protein was detected in proliferating WWOX-knockdown HEK-293T cells and Wwox knockout MEFs, suggesting that WWOX plays an important role in regulating DDR signaling for maintaining genome stability upon replication stress. Our findings delineate the regulatory role of WWOX in DDR and have great impact on our understanding of molecular pathogenesis of cancer and senescence-related diseases. Citation Format: Li-Jin Hsu. The functional role of tumor suppressor WW domain-containing oxidoreductase in maintaining genome integrity [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 2839.