Overexpression of the Telomerase Holoenzyme Induces EMT and Tumorigenesis of HPV-Immortalized Keratinocytes.

Cervical cancer is the most frequent malignancy of the female genital tract and is associated with persistent infection of the uterine cervix with high-risk human papillomaviruses (HPV). The two HPV oncoproteins, E6 and E7, cooperatively immortalize cervical cells and are essential but insufficient for inducing tumorigenicity. During the progression of HPV-associated cervical dysplasia to carcinoma, the cellular TERT gene is activated and the TERC gene amplified. We questioned whether these increases in telomerase components might mediate the acquisition of the tumorigenic phenotype. We therefore transduced the TERT and TERC genes into E6/E7 immortalized keratinocytes that were anchorage-dependent and non-tumorigenic. The resultant cells showed a profound morphological change characteristic of epithelial-mesenchymal transition (EMT) as well as a corresponding increase in expression of vimentin, N-cadherin, ZEB1, SNAIL and MMP2 and decrease in keratin and E-cadherin. More important, the transduced cells were now anchorage-independent and formed tumors in immunodeficient mice. Our findings indicate that overexpression of the telomerase holoenzyme in HPV-immortalized cells is sufficient to induce the complete transformed phenotype. This article is protected by copyright. All rights reserved.