Pleiotropic effects of human papillomavirus type 16 E6 oncogene expression in human epithelial cell lines

Two human papillomavirus (HPV)-negative epithelial cell lines, HaCaT and C33A, were transfected with HPV-16 E6 and analysed for functional consequences which are relevant to invasive tumour progression. After transfection with E6, both cell lines invaded collagen matrices, in contrast to vector-transfected control cells. The E6-expressing cells showed a marked increase in expression of the beta1 integrin subunit, with no or relatively minor alterations in the levels of a range of integrin subunits. In addition, the epithelial cell lines expressing E6 displayed resistance to apoptosis generated by serum starvation. This resistance is comparable to that generated by ras and is not generated by HPV-11 E6 or HPV-16 E7. Both C33A and HaCaT cells have mutations in the p53 loci and hence these functional consequences of E6 are probably independent of wild-type p53 function.