Loss of fragile WWOX gene leads to senescence escape and genome instability

• Published in: Cellular and molecular life sciences : CMLS 2023-11, Vol.80 (11), p.338-338, Article 338
• Main Authors: Cheng, Hui-Ching, Huang, Po-Hsien, Lai, Feng-Jie, Jan, Ming-Shiou, Chen, Yi-Lin, Chen, Szu-Ying, Chen, Wan-Li, Hsu, Chao-Kai, Huang, Wenya, Hsu, Li-Jin
• Format: Article
• Language: English
• Subjects: Acetylcysteine; Anomalies; Apoptosis; Biochemistry; Biodegradation; Biomedical and Life Sciences; Biomedicine; Cell Biology; Cell culture; Cell cycle; Cell proliferation; Chromosomes; Cyclin-dependent kinase; Cyclin-dependent kinase inhibitor p21; Cyclin-dependent kinase inhibitor p27; Cyclin-dependent kinase inhibitors; Cyclin-dependent kinases; Damage; Deoxyribonucleic acid; DNA; DNA biosynthesis; DNA damage; Embryo fibroblasts; Fibroblasts; Genomes; Genomic instability; GTP-binding protein; INK4a protein; Integrity; Kinases; Life Sciences; Metaphase; Microsatellite instability; Original; Original Article; Oxidative stress; p16 Protein; p53 Protein; Proteins; Radiation effects; Reactive oxygen species; Replication; Senescence; Ultraviolet radiation
• ISSN: 1420-682X; 1420-9071
• DOI: 10.1007/s00018-023-04950-1

Induction of DNA damage response (DDR) to ensure accurate duplication of genetic information is crucial for maintaining genome integrity during DNA replication. Cellular senescence is a DDR mechanism that prevents the proliferation of cells with damaged DNA to avoid mitotic anomalies and inheritance of the damage over cell generations. Human WWOX gene resides within a common fragile site FRA16D that is preferentially prone to form breaks on metaphase chromosome upon replication stress. We report here that primary Wwox knockout ( Wwox −/− ) mouse embryonic fibroblasts (MEFs) and WWOX-knockdown human dermal fibroblasts failed to undergo replication-induced cellular senescence after multiple passages in vitro. Strikingly, by greater than 20 passages, accelerated cell cycle progression and increased apoptosis occurred in these late-passage Wwox −/− MEFs. These cells exhibited γH2AX upregulation and microsatellite instability, indicating massive accumulation of nuclear DNA lesions. Ultraviolet radiation-induced premature senescence was also blocked by WWOX knockdown in human HEK293T cells. Mechanistically, overproduction of cytosolic reactive oxygen species caused p16 Ink4a promoter hypermethylation, aberrant p53/p21 Cip1/Waf1 signaling axis and accelerated p27 Kip1 protein degradation, thereby leading to the failure of senescence induction in Wwox -deficient cells after serial passage in culture. We determined that significantly reduced protein stability or loss-of-function A135P/V213G mutations in the DNA-binding domain of p53 caused defective induction of p21 Cip1/Waf1 in late-passage Wwox −/− MEFs. Treatment of N -acetyl- l -cysteine prevented downregulation of cyclin-dependent kinase inhibitors and induced senescence in Wwox −/− MEFs. Our findings support an important role for fragile WWOX gene in inducing cellular senescence for maintaining genome integrity during DDR through alleviating oxidative stress.