Functional dissociation of transforming genes of human papillomavirus type 16

Human papillomavirus (HPV) type 16 is thought to be responsible for development of cervical carcinomas, but the mechanism of its carcinogenic action is unknown. To determine which viral genes are involved in cellular transformation, we constructed recombinant murine retrovirus DNAs containing various subgenomic fragments of the HPV 16 early region and examined their transforming activities. The results show that the E6 and E7 ORFs are the transforming genes of HPV 16; the former governs the tumorigenicity in nude mice and the latter influences cell growth properties such as saturation density and colony formation in soft agar. There may also be a tumor-suppressing gene in the E1-E2 ORF region, because the tumorigenic activity of recombinant DNA containing the E1 ORF and the 5' portion of the E2 ORF in addition to the E6 and E7 ORFs was much lower than that of recombinant DNA containing only the E6 and E7 ORFs.