Curcumin suppresses breast tumor angiogenesis by abrogating osteopontin-induced VEGF expression

The development and progression of malignant tumors depends on the formation of new blood vessels inside the tumor. This phenomenon is termed tumor angiogenesis. Angiogenesis is one of the fundamental processes that occur during cancer progression, and depends on the expression and activation of various angiogenic molecules, cytokines, growth factors, kinases and transcription factors. We recently demonstrated that the chemokine-like ECM-associated protein osteopontin (OPN) turns on the angiogenic switch by upregulating expression of vascular endothelial growth factor (VEGF) in a human breast cancer model. Furthermore, we proposed that targeting OPN-induced VEGF expression could be a potential therapeutic approach for the treatment of breast cancer. In this study, we demonstrate that curcumin (diferuloylmethane) abrogates OPN-induced VEGF expression and curbs OPN-induced VEGF-dependent breast tumor angiogenesis in vivo. We also explore the fact that curcumin in combination with anti-VEGF or anti-neuropilin (NRP)-1 antibody exhibits enhanced anti-angiogenic activity compared to curcumin alone. Our results indicate that curcumin suppresses OPN-induced VEGF expression and tumor angiogenesis, and suggest that this study may aid in the development of a curcumin-based OPN-targeted therapeutic approach to the control of breast tumor angiogenesis.