Vascular endothelial growth factor (
VEGF) is one of the most important angiogenic
growth factors for
tumor angiogenesis. Here, we sought to explore whether RNA interference (RNAi) targeting
matrix metalloproteinase-2 (MMP-2) could disrupt
VEGF-mediated angiogenesis in
lung cancer. MMP-2
siRNA inhibited
lung cancer cell-induced tube formation of endothelial cells in vitro; addition of recombinant human-MMP-2 restored angiogenesis. MMP-2 transcriptional suppression decreased
VEGF,
phosphatidylinositol 3-kinase (PI3K)
protein levels and AKT phosphorylation in
lung cancer cells. In addition, MMP-2 suppression decreased
hypoxia inducible factor-1alpha (HIF-1alpha), a
transcription factor for
VEGF, as determined by electrophoretic mobility shift assay (EMSA). We also show that MMP-2 suppression disrupted PI3K dependent
VEGF expression; ectopic expression of myr-AKT restored
VEGF inhibition. Further, MMP-2 suppression decreased the interaction of integrin-alphaVbeta3 and MMP-2 as confirmed by immunoprecipitation analyses. Studies with either function blocking integrin-alphaVbeta3 antibody or MMP-2 specific inhibitor (ARP-100) indicate that suppression of MMP-2 decreased integrin-alphaVbeta3-mediated induction of PI3K/AKT leading to decreased
VEGF expression. Moreover, A549 xenograft tissue sections from mice that treated with MMP-2
siRNA showed reduced expression of
VEGF and the angiogenic marker,
factor-VIII. The inhibition of
tumor angiogenesis in MMP-2 suppressed
tumor sections was associated with decreased co-localization of integrin-alphaVbeta3 and MMP-2. In summary, these data provide new insights into the mechanisms underlying MMP-2-mediated
VEGF expression in lung
tumor angiogenesis.