Haixia Yang, EnxiaoLi

Department of MedicalOncology, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China

Objective:RHOC, as a member of the Ras superfamilyof GTP-binding proteins, has been demonstrated to be involved in metastasis ofmany human malignancies; however, its role in human cholangiocellular carcinoma(CCC) is still largely unknown. The aim of this study was to investigate RHOCexpression in CCC and its prognostic significance. The effect of RHOC on humancholangiocellular carcinoma cell (CCC) invasion and possibly molecularmechanism were also investigated. Method: 86 surgery patients of CCCwere enrolled from March 2008 to December 2013 after signing the informedconsent. Matched tumor tissues and adjacent tumor free tissues were obtained.Patients' clinicopathological data including gender, age, TNM stages andpathological grades were retrieved from medical records. The median follow-upperiod was 15.4 months at an interval of every 3months after the surgery. Thecorrelation of RHOC expression with clinicopathological features includingsurvival was analyzed. To investigate the effect and possibly molecularmechanism of RHOC on CCC cell invasion, we constructed lentivirus shRNA RHOCvector and transfected into human cholangiocellular carcinoma cell RBE. Cellinvasion capacity was determined by transwell assays. The protein expression ofRHOC, MMP2, MMP3, MMP9, MMP14, Vimentin, Snail, Slug and E-cadherin wereevaluated by western blot in transfected and non-transfected RBE cells. Result:Immunohistochemical staining results revealed that RHOC expression wassignificantly up regulated in 86 CCC tissues relative to their adjacentnon-cancerous tissues (P<0.01). Moreover, RHOC expression wassignificantly higher in CCC with lymph node metastasis compared with thatwithout lymph node metastasis (P<0.05). Patients with high expressionlevel of RHOC showed favorable 5 year overall survival (P<0.05). Amultivariate analysis showed that RHOC expression was an independent prognosticfactor of OS in patients with CCC. Knockdown of RHOC inhibited CCC cellinvasion and decreased the expression of MMP2, MMP9, Vimentin, Snail and Slug;while no significant change was observed in the expression of MMP3 and MMP14;on the contrary, down regulated RHOC significantly increased the expression ofadhesion factor E-cadherin. Conclusion: Our data suggest that RHOC playsa vital role in CCC progression and may act as a novel prognostic marker in CCCpatients. The molecular mechanism of RHOC on CCC cell invasion possiblyinvolved in MMPs and EMT associated genes, suggesting that RHOC is a potentialmolecular target for CCC treatment.

KeyWords: human  cholangiocellular carcinoma (CCC)  RHOC invasion