The role of miR-18a in gastric cancer angiogenesis.

BACKGROUND/AIMS: To investigate the effect of miR-18a on angiogenesis in gastric cancer.

METHODOLOGY: We generated stable cell lines overexpressing miR-18a in SGC-7901 cells. Cell proliferation was assessed by the MTT assay. The effects of miR-18a overexpression on tumor growth and angiogenesis were assessed. Because of the key role of mammalian target of rapamycin (mTOR) signaling in gastric cancer progression, we also tested whether miR-18a overexpression affected the mTOR pathway.

RESULTS: Ectopic expression of miR-18a significantly diminished cell proliferation in SGC-7901 cells (p<0.01). miR-18a overexpression significantly retarded SGC-7901 xenograft growth by 71.8% in vivo, and caused a marked reduction in tumor angiogenesis assessed by CD31-stained microvessel count. Western blot analysis of the xenografts showed that miR-18a overexpression substantially reduced the phosphorylation of two mTOR substrates, S6K1 and 4E-BPl, indicative of art inactivation of the mTOR pathway. Accompanying with the mTOR inactivation, the angiogenic factors, hypoxia-inducible factor 1 alpha and vascular endothelial growth factor, were significantly downregulated.

CONCLUSIONS: These data highlighted an important role for miR-18a in controlling gastric cancer growth and angiogenesis, therefore offering a possible therapeutic strategy against this malignancy.