beta 1 integrins mediate tubule formation induced by supernatants derived from KSHV-infected cells

Objective: Angiogenesis is defined as the formation of new blood vessels. In a recently concluded study, we identified Kaposi's sarcoma-associated herpesvirus (KSHV)-infected cells derived from primary effusion lymphoma ( PEL) to overexpress vascular endothelial growth factor (VEGF) that had the propensity to mediate tubule formation on a Matrigel, an indicator of angiogenesis. The objective of this study was to determine the receptor molecules that mediate the tubule formation induced by the supernatant derived from KSHV-infected PEL cells. Methods: The identity of receptor(s) that play a role in mediating tubule formation driven by PEL supernatant was determined by the classical in vitro angiogenesis assay conducted on a Matrigel. Results: RGD peptides, antibodies, and siRNA specific to beta 1 integrins significantly lowered the ability of the PEL supernatants to induce tubule formation by endothelial cells. beta 1 Integrins mediated tubule formation to comparable levels in endothelial cells that were incubated with supernatants derived from uninduced or TPA- induced PEL cells. Interestingly, the beta 1 integrins did not seem to have a major role in cellular attachment. Conclusion: We report for the first time a critical role for beta 1 integrins in angiogenesis supported by the supernatant from KSHV-infected PEL cells. Copyright (C) 2007 S. Karger AG, Basel.