Extremely stringent activation of p16INK4a prevents immortalization of uterine cervical epithelial cells without human papillomavirus oncogene expression.

Extremely stringent activation of p16INK4a prevents immortalization of uterine cervical epithelial cells without human papillomavirus oncogene expression. Oncotarget. 2016 Jun 17; Authors: Hang S, Tiwari AF, Ngan HY, Yip YL, Cheung AL, Tsao SW, Deng W Abstract Cervical epithelial cell immortalization with defined genetic factors without viral oncogenes has never been reported. Here we report that HPV-negative cervical epithelial cells failed to be immortalized by telomerase activation or the combination of p53 knockdown and telomerase activation. Under those conditions, p16INK4a expression was always elevated during the late stage of limited cell lifespan, suggesting that cervical epithelial cells possess an intrinsic property of uniquely stringent activation of p16INK4a, which may offer an explanation for the rarity of HPV-negative cervical cancer. Combining p16INK4a knockdown with telomerase activation resulted in efficient immortalization of HPV-negative cervical epithelial cells under ordinary culture conditions. Compared with the HPV16-E6E7-immortalized cell lines derived from the same primary cell sources, the novel HPV-negative immortalized cell lines had lower degrees of chromosomal instability, maintained more sensitive p53/p21 response to DNA damage, exhibited more stringent G2 checkpoint function, and were more resistant to replication-stress-induced genomic instability. The newly immortalized HPV-negative cervical epithel...
Source: Oncotarget - Category: Cancer & Oncology Tags: Oncotarget Source Type: research