Overexpression of ARHI suppresses tumor angiogenesis in hepatocellular carcinoma / 中华肝胆外科杂志

ABSTRACT

Objective To investigate the effect of the Ras-related tumor suppressor gene aplasia Ras homolog member Ⅰ (ARHI) on angiogenesis in hepatocellular carcinoma (HCC).Methods We generated stable cell lines overexpressing ARHI in Hep3B cells,which lack endogenous ARHI.Cell proliferation was assessed by the MTT assay.The effects of ARHI overexpression on tumor growth and angiogenesis were assessed.Because of the key role of mammalian target of rapamycin (mTOR)signaling in HCC progression,we also tested whether ARHI overexpression affected the mTOR pathway.Results Ectopic expression of ARHI significantly diminished cell proliferation in Hep3B cells (P＜0.01).ARHI overexpression significantly retarded Hep3B xenograft growth by 76.4 ％ in vivo,and caused a marked reduction in tumor angiogenesis assessed by CD31-stained microvessel count.Western blot analysis of the xenografts showed that ARHI overexpression substantially reduced the phosphorylation of two mTOR substrates,S6K1 and 4E-BP1,indicative of an 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.Conclusion These data highlighted an important role for ARHI in controlling HCC growth and angiogenesis,therefore offering a possible therapeutic strategy against this malignancy.