Oestrogen and progesterone increase the levels of apoptosis induced by the human papillomavirus type 16 E2 and E7 proteins

Authors:
Publisher website
Google Scholar
Abstract
Human papillomavirus (HPV) type 16 infects the genital tract and is generally acknowledged to be a causative agent of cervical cancer. HPV infection alone is not sufficient to induce cervical cancer and other factors such as steroid hormones are thought to play a role in the establishment and/or progression of this disease. The HPV-16 E2 protein is required for virus replication and modulates viral gene expression whereas the HPV-16 E7 protein is required for cell transformation. We and others have shown that both the E2 and E7 proteins can induce apoptotic cell death in HPV-transformed and non-HPV transformed cell lines. Here we show that the steroid hormones oestrogen and progesterone can both increase the levels of E2- and E7-induced apoptosis. The oestrogen metabolite 16α-hydroxyoestrone also increases E2- and E7-induced cell death and the dietary component indole-3-carbinol, which reduces the formation of 16α-hydroxyoestrone from oestrogen, blocks the effects of oestrogen. Thus the metabolism of oestrogen to 16α-hydroxyoestrone appears to be required for the effects of this hormone on E2- and E7-induced cell death. We also show that the oestrogen receptor antagonist 3-hydroxytamoxifen blocks the effects of oestrogen on E2- and E7-induced cell death, whereas the anti-progesterone RU486 blocks the effects of both progesterone and oestrogen. We discuss these results in terms of the origin and progression of cervical cancer.

This publication has 45 references indexed in Scilit: