Immortalization of normal human oral keratinocytes with type 16 human papillomavirus

Abstract

Primary human oral keratinocytes were transformed by transfection with recombinant human papillomavirus type 16 (HPV-16)DNA, and two transformed cell lines named human oral keratinocytes-16A and -16B (HOK-16A and HOK-16B) were established. While normal cells and cells transfected with vector only exhibited a limited Wespan, the HOK-16A and HOK-16B lines demonstrated immortality and altered morphology from their normal counterpart. The HOK-16A and HOK-16B lines contained ˜40 and ˜25 copies of intact HPV-16 DNA as integrated form per cell respectively, and both cell lines exprpssed several viral specific poly(A⁺) RNAs. Notably these cell lines also overexpressed cellular myc proto-oncogene in comparison with the normal counterpart. However, the immortalized cell lines were not able to produce tumors in nude mice, indicating that the cells are partially transformed. The HOK-16A and HOK-16B lines are, therefore, useful for investigating the multistep molecular events of oral carcinogenesis.