Knockdown of RAGE expression inhibits colorectal cancer cell invasion and suppresses angiogenesis in vitro and in vivo.

The receptor for advanced glycation end-products (RAGE) is a transmembrane receptor in cells, and the interaction of RAGE with ligands results in pro-inflammatory gene activation. Aberrant RAGE activation was reported to promote the pathogenesis of colorectal cancer. This study aimed to investigate the effects of RAGE on the regulation of cell viability, invasion, and angiogenesis, as well as the underlying molecular mechanisms regulating these interactions in colorectal cancer cells. The RAGE mRNA and protein were evaluated in five colorectal cancer cell lines and in 45 cases of colorectal cancer tissue specimens (using immuohistochemistry). RAGE expression was then knockdown using RAGE shRNA for assessing cell viability and invasion assays as well as for tube formation and CAM assays in human umbilical vein endothelial cells and chick embryos, respectively. RAGE was highly expressed in colorectal cancer tissues, and was associated with increased microvessel density. Two of the four RAGE shRNA constructs were able to significantly knockdown RAGE expression in SW480 cells. RAGE knockdown inhibited invasion capacity of SW480 cells, but did not significantly affect cell viability. Furthermore, the conditioned growth medium from stable RAGE shRNA-transfected cells suppressed tube formation of human umbilical vein endothelial cells and angiogenesis of chicken embryos. Knockdown of RAGE inhibited expression of VEGF and SP1 protein in colorectal cancer cells. In summary, these data suggest that silence of RAGE expression could effectively inhibit colorectal cancer angiogenesis in vitro and in vivo.