Simvastatin inhibits tumor angiogenesis in HER2-overexpressing human colorectal cancer

Overexpression of the HER2 oncogene contributes to tumor angiogenesis, which is an essential hallmark of cancer. Simvastatin has been reported to exhibit antitumor activities in several cancers; however, its roles and molecular mechanismsin the regulation of colorectal angiogenesis remain to be clarified. Here, we show that colon cancer cells express high levels of VEGF, total HER2 and phosphorylated HER2, and simvastatin apparently decreased their expression in HER2-overexpressing colon cancer cells. Simvastatin pretreatment reduced endothelial tube formation in vitro and microvessel density in vivo. Furthermore, simvastatin markedly inhibited tumor angiogenesis even in the presence of heregulin (HRG)-β1 (a HER2 co-activator) pretreatment in HER2+ tumor cells. Mechanistic investigation showed that simvastatin significantly abrogated HER2-induced tumor angiogenesis by inhibiting VEGF secretion. Together, these results provide a novel mechanism underlying the simvastatin-induced inhibition of tumor angiogenesis through regulating HER2/VEGF axis.