Cooperative Roles of Tat & K-Cyclin in Kaposi's Sarcoma

  • Li, Mengtao (PI)
  • Lin, Yi Ling (CoI)

Grants and Contracts Details


Kaposi's sarcoma (KS) is a malignant tumor of endothelial origin and the most frequent cancer in AIDS patients, Sixty percent of AIDS-associated KS initiate in the oral cavity, representing a serious problem in oral health. Despite identification of human herpesvirus 8 (HHV-8) as the etiological agent for all forms of KS, the extraordinarily higher prevalence of KS in HIV-infected patients suggests a cooperative interaction between HIV and HHV-8 in the development of KS. HIV Tat is one of the key regulating factors for viral gene expression and plays many roles in HIVassociated pathogenesis. Tat causes dysfunction and transformation of cultured endothelial cells and induces KS-like lesions in transgenic animals. HHV-8 k-cyclin, a homologue of cellular cyclin D, disrupts cell growth control by aberrantly activating Cdk6 and accelerating the G1/S transition of the cell cycle. The expression of k-cyclin promotes proliferation of endothelial cells. We have found that Tat interacts with k-cyclin in vivo, providing evidence of pathological links between HIV and HHV-8. Here, we propose to study the cooperative roles of Tat and k-cyclin in the development of KS by using immortalized primary endothelial cells. Using this in vitro model, we will dissect steps that are responsible for the HHV-8-infected endothelial cells to progress toward the development of KS malignancy. The specific aims are: (1) define the molecular interaction between Tat and k-cyclin and examine kinase activities associated with these two proteins, (2) determine cooperative effects of Tat and k-cyclin in promoting the proliferation of endothelial cells, (3) demonstrate roles of Tat in enhancing HHV-8 infection and HHV-8-induced cell transformation. These studies will increase our understanding of the pathogenesis of AIDS-associated KS, the cooperative role of Tat and k-cyclin, and suggest a strategy in combating this tumor.
Effective start/end date6/1/055/31/08


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