Kaposi's sarcoma associated herpesvirus G-protein coupled receptor activation of cyclooxygenase-2 in vascular endothelial cells

BACKGROUND: Kaposi's sarcoma associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS), a highly vascularized neoplasm characterized by endothelial-derived spindle-shaped tumor cells. KSHV-infected microvascular endothelial cells demonstrate increased cyclooxygenase-2 (COX-2) expression and KS lesions have high levels of prostaglandin E(2 )(PGE(2)), a short-lived eicosanoid dependent on cyclooxygenase activity that has been linked to pathogenesis of other neoplasias. To determine whether increased COX-2 expression and PGE(2 )production is mediated by the angiogenic and tumorigenic KSHV-encoded G-protein coupled receptor (vGPCR), we developed a recombinant retrovirus to express vGPCR in Human Umbilical Vascular Endothelial Cells (HUVEC). RESULTS: In the present study, we show that vGPCR-expressing HUVEC exhibit a spindle-like morphology that is characteristic of KS endothelial cells and demonstrate selective induction of PGE(2 )and COX-2. By treating vGPCR-expressing HUVEC with selective and non-selective COX inhibitors, we show that vGPCR-induced PGE(2 )production is dependent on the expression of COX-2 but not COX-1. CONCLUSION: Taken together, these results demonstrate that vGPCR induces expression of COX-2 and PGE(2 )that may mediate the paracrine effects of this key viral protein in KS pathogenesis.