MiR-182-5p inhibits colon cancer tumorigenesis, angiogenesis, and lymphangiogenesis by directly downregulating VEGF-C.

MicroRNAs (miRNAs) are gene modulators essential for biological processes. However, the precise functions of miRNAs in growth and development of colon cancer are still elusive. To clarify their role, here we analyzed a miRNA microarray of colon cancer. MiR-182-5p was found markedly downregulated in colon cancer tissues and cells, and strongly correlated with pathological stage, differentiation, and lymphatic metastasis. In vitro, miR-182-5p overexpression repressed colon cancer cell proliferation, colony formation, migration, and invasion, and triggered G1 arrest and apoptosis. MiR-182-5p overexpression also downregulated vascular endothelial growth factor (VEGF)-C and inhibited the activity of a luciferase reporter containing the VEGF-C 3'-untranslated region. Moreover, miR-182-5p overexpression in colon cancer cells and human umbilical vein endothelial cells (HUVECs) downregulated VEGF-A as well as VEGF receptor (VEGFR)-2 and VEGFR-3, thereby inhibiting the phosphorylation of ERK and AKT. In vivo, miR-182-5p overexpression strikingly suppressed oncogenicity of SW620 cells as well as angiogenesis and lymphangiogenesis of xenograft tumors in nude mice. These data indicate that miR-182-5p regulates colon cancer tumorigenesis partially through modulating angiogenesis and lymphangiogenesis by targeting VEGF-C, and inhibiting ERK and AKT signaling pathways.