Rhein inhibits invasion and migration of human nasopharyngeal carcinoma cells in vitro by down-regulation of matrix metalloproteinases-9 and vascular endothelial growth factor

Abstract

Progression of cancer invasion is believed to be dependent on the remodeling of extracellular matrix induced by tumor cells. Rhein has been shown to inhibit the growth and proliferation of human nasopharyngeal carcinoma (NPC) cells. However, the molecular mechanism underlying rhein-induced inhibition of cancer invasion has not been explored. Herein, we show that rhein could inhibit the invasion and migration of NPC cells in vitro. Rhein inhibits invasion by reducing the expression of matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF). Moreover, we demonstrate that the pathway involved in rhein-inhibited invasion is presumably through the growth factor receptor bound protein 2/son of sevenless-Ras-mitogen-activated protein kinase (GRB2/SOS-Ras-MAPK) pathway, as shown by an decrease in the expression levels of GRB2, SOS-1 and Ras as well as led to suppression of the phosphorylation of extracellular signal-regulated kinase (ERK) and p38 MAPK. Further study has shown that rhein also inhibited activation of transcription factor nuclear factor kappaB (NF-kappaB), which is known to implicate the regulation of MMP-9 and VEGF gene expression in cancer invasion. Our findings suggest that rhein inhibits the invasion of NPC cells may be mediated in part through the suppression of MMP-9 and VEGF expression via the modulation of NF-kappaB signaling pathway.