Enhancement of human papillomavirus type 18 gene expression in HeLa cells by 12-O-tetradecanoylphorbol-13-acetate, 3 beta,5 alpha-dihydroxycholestan-6-one, and cholesterol.

Human papillomavirus type 18 (HPV18) is involved in the genesis of cervical cancer through expression of its viral oncoprotein in infected cells. A tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), was found to increase the level of HPV18 transcripts in an HPV18-harboring cervical cancer cell line, HeLa. A similar increase in HPV18 expression was also observed on treatment of the cells with an oxygenated cholesterol, 3 beta,5 alpha-dihydroxycholestan-6-one (yakkasterone). The effects on HPV18 expression elicited by TPA and yakkasterone were repressed by a protein kinase inhibitor, staurosporine. Treatment of the cells with cholesterol under serum-free conditions also resulted in an apparent increase of HPV18 expression.