DEGRADATION OF P53 ONLY IS NOT SUFFICIENT FOR THE GROWTH-STIMULATORY EFFECT OF HUMAN PAPILLOMAVIRUS-16 E6 ONCOPROTEIN IN HUMAN EMBRYONIC FIBROBLASTS

Certain types of human papillomavirus (HPV), such as types 16 and 18, are thought to be responsible for the development of cervical carcinom as. The E6 and E7 genes of these viruses have transforming activities in various cultured cells and their mRNAs and proteins are expressed i n almost all cervical carcinoma cells. Inactivation of the tumor suppr essor p53 protein by the E6 gene is believed to be critical for transf ormation by these oncogenic HPVs. To determine whether degradation of the p53 protein is, in fact, sufficient for cellular transformation by the E6 gene, the E6 gene of HPV16 was introduced into human embryonic fibroblasts (HEF) using recombinant murine retrovirus and examined wh ether reduction of the p53 protein could substitute for the E6 functio n. It was found that HEF cells transfected with the E6 gene showed an increased saturation density and degraded the p53 protein. However, wh en expression of the p53 protein in normal HEF cells was suppressed by the antisense oligonucleotide of the p53 gene, growth stimulation was not observed. These results show that the E6 gene stimulates growth o f HEF cells, but that this activity involves some other E6 gene-mediat ed functions than degradation of the p53 protein. (C) 1994 Wiley-Liss, Inc.