Transacting activities of the E7 genes of several types of human papillomavirus.

In accordance with previous reports by others, the E7 gene of human papillomavirus (HPV) 16, considered to be etiologically associated with cervical cancer, transactivated the E2 promoter of adenovirus. This promoter, however, was equally stimulated by the E7 gene of HPV1, a skin type HPV never associated with human malignancy. A variety of promoters were tested to see the effect of the E7 genes of low-risk and high-risk type HPVs. The result indicated that there was no obvious relationship in the levels of transactivation or transrepression by the E7 gene between low-risk and high-risk types. It has been suggested that the binding of the E7 protein to the product of retinoblastoma susceptibility gene (pRb) is the underlying mechanism by which the E7 protein transactivates the E2 promoter. Therefore, the association of the E7 protein and pRb alone did not seem to fully explain the mechanism by which this protein participates in the activation of transcription and induction of human malignancies.