Human ovarian surface epithelial cells immortalized with hTERT maintain functional pRb and p53 expression.

Cell immortalization is considered to be a prerequisite status for carcinogenesis. Normal human ovarian surface epithelial (OSE) cells, which are thought to be the origin of most of human ovarian carcinomas, have a very limited lifespan in culture. Establishment of immortalized OSE cell lines has, in the past, required inactivation of pRb and p53 functions. However, this often leads to increased chromosome instability during prolonged culture. In this study, we have used a retroviral infection method to overexpress human telomerase reverse transcriptase (hTERT) gene, in primary normal OSE cells, under optimized culture conditions. In vitro and in vivo analysis of hTERT-immortalized cell lines confirmed their normal epithelial characteristics. Gene expression profiles and functional analysis of p16(INK4A), p15(INK4B), pRb and p53 confirmed the presence of their intact functions. Our study suggests that inactivation of pRb and p53 is not necessary for OSE immortalization. Furthermore, down-regulation of p15(INK4B) in the immortalized cells may indicate a functional role for this protein in them. These immortal OSE cell lines are likely to be an important tool for studying human OSE biology and carcinogenesis.