Abstract
Curcumin is a key polyphenolic curcuminoid extracted from the root of turmeric rhizome Curcuma longa Linn, which is a frequently used Chinese herb for the treatment of cancer. The aim of the present study was to investigate the mechanism of the inhibitory effects of curcumin on nude mice with lung cancer A549 cell subsets side population (SP) and non-SP (NSP) cells. BALB/c mice were subcutaneously injected with the tumor cells of A549 SP or NSP subsets consisting of 1×109 cells/l (0.2 ml in total). After 16 days of inoculation with A549, the mice were intraperitoneally injected with curcumin (100 mg/kg, 0.2 ml) once every other day, eight times in total. A series of assays were performed to detect the effects of curcumin on: i) Tumor weight and size; ii) Notch and hypoxia inducible factor 1 (HIF-1) mRNA expression by quantitative polymerase chain reaction; and iii) vascular endothelial growth factor (VEGF) and nuclear factor-κB (NF-κB) by immunohistochemistry. It was determined that curcumin decreased the tumor weight and size, downregulated the expression of Notch and HIF-1 mRNA and suppressed the VEGF and NF-κB expression. These results indicated that curcumin inhibited lung cancer growth through the regulation of angiogenesis mediated by VEGF signaling.