Telomerase Prolongs the Lifespan of Normal Human Ovarian Surface Epithelial Cells Without Inducing Neoplastic Phenotype

Abstract

The aim of this study was to determine the effects of exogenous expression of the catalytic subunit of telomerase (hTERT) on the lifespan, growth characteristics, and tumorigenicity of normal human ovarian surface epithelial (OSE) cells. Low-passage primary cultures of normal human OSE cells were transfected with hTERT and the resulting cell lines were characterized. The ectopic expression of hTERT stabilized the telomeres of the OSE cultures above 8 kb. The hTERT-transfected OSE cell lines grew beyond the normal lifespan seen in OSE cells and propagated in culture for more than 40 passages before senescing. Moreover, the hTERT-transfected cells demonstrated extensive proliferative capacity as evidenced by their ability to continuously grow even when seeded at low dilutions. The morphologic features and normal differentiation patterns seen in normal OSE cells were likewise retained by the hTERT-transfected cells. In addition, the cultures remained responsive to physiologic concentrations of epidermal growth factor and transforming growth factor-beta. Changes associated with neoplastic transformation like anchorage-independent growth, tumorigencity and karyotypic instability were not observed. We were able to show that the ectopic expression of hTERT in normal human OSE: 1) resulted in cultures with greater growth potential and longer lifespan and 2) did not induce a transformed phenotype previously seen in viral oncogene-transfected OSE cells. The established cell lines would not only provide sufficient material for comprehensive studies to investigate the normal physiology of OSE cells, but could also help in the understanding of the early steps of ovarian carcinogenesis.