Infection with the human papillomaviruses (HPV) induces warts and is strongly associated with the development of cervical cancer. Our long-term goal is to elucidate the molecular basis for HPV-induced lesions and to develop therapeutic strategies for the elimination of HPV infection, Apoptosis is a genetically programmed process of cellular destruction that can eliminate virally infected cells or tumors. Viruses such as HPV have evolved specific gene products to modulate apoptosis. Induction of apoptosis is a desirable approach in treating HPV-induced lesions. The HPV E6 gene is essential for viral replication and induces apoptosis. However, the mechanism by which E3 mediates cellular sensitization to apoptosis remains to be determined. To understand the molecular basis for E6-mediated apoptosis, we have established human keratinocytes expressing HPV E6 and found these cells to be susceptible to apoptosis induced by chemotherapeutic agents. To identify genes responsible for E6-mediated apoptosis, a proteomic approach was taken. Significantly, the level and activity of Cdc2, the cyclin-dependent kinase required for cells to enter mitosis and whose aberrant activation has been associated with apoptosis, was increased in E6-expressing cells undergoing apoptosis. An E6 mutant that is unable to activate Cdc2 is defective in sensitizing cells to apoptosis. Moreover, inhibition of Cdc2 activity with specific inhibitor reduced ap6ptosis. We hypothesize that activation of Cdc2 plays an important role in E6-mediated cellular sensitization to apoptosis.
The specific aim of this proposal is designed to test this possibility with the following approaches: (1) to examine the relevance of Cdc2 to E6-mediated cellular sensitization to apoptosis through a genetic approach and (2) to determine the role of Cdc2 in E6-mediated apoptosis by molecular ablation and ectopic expression. These studies will help understand the mechanism of E6-mediated apoptosis and contribute to the development of therapeutic approaches against HPV-induced diseases.
| Liu, Zhi-Guo; Zhao, Li-Na; Liu, Ying-Wang et al. (2007) Activation of Cdc2 contributes to apoptosis in HPV E6 expressing human keratinocytes in response to therapeutic agents. J Mol Biol 374:334-45 |
