Clinical Significance And Biological Function Of Co-stimulation Molecule B7-H6 Expression In Human Hepatocellular Carcinoma

Objectives:To investigate the clinical significance and biological function of co-stimulatory molecule B7-H6 in human hepatocellular cancer.Methods:The immunohistochemistry assay and the tissue micro-array were used to examine the B7-H6 expression in hepatocellular cancer tissues.The correlation between the expression level of B7-H6 and patients' clinic pathological parameters was evaluated by using chi-square test.Down-regulation of B7-H6 was performed by using RNAi method to investigate the role of B7-H6 in regulation of biological behaviors in human hepatocellular cancer cell lines HepG2 and SMMC-7721.The CCK-8,wound healing,and transwell were used to examine the cellular function after B7-H6 knockdown of these cells.Results:The B7-H6 expression level in hepatocellular cancer tissues was significantly correlated with patients' age(P=0.015)and tumor size(P=0.034).There were no significant correlations between B7-H6 expression and patients' gender,pathological grading,pathological type and T stage.Next,to investigate the functions of B7-H6 in HCC,we successfully constructed B7-H6 knockdown expression human hepatocellular cell lines using the RNA interference technology.CCK-8 assay showed that decreased B7-H6 expression in human hepatocellular cancer lines HepG2 and SMMC-7721 significantly attenuated cell proliferation(HepG2,48h:P<0.05,72h:P<0.01:SMMC-7721,48h:P<0.05,72h:P<0.05).The wound healing assay showed that decreased B7-H6 expression in human hepatocellular cancer lines HepG2 and SMMC-7721 significantly attenuated cell migration(HepG2,24h:P<0.05,36h:P<0.01;SMMC-7721,36h:P<0.01).The Transwell assay showed that decreased B7-H6 expression in human hepatocellular cancer lines HepG2 and SMMC-7721 significantly attenuated cell invasion(HepG2,24h:P<0.01,36h:P<0.001;SMMC-7721,24h:<0.001,36h:P<0.001).Conclusions:Our results showed that the co-stimulatory molecule B7-H6 was expressed abnormally in HCC tissues,which was greatly related to patients' age and tumor size.Also,our studies showed that reduced expression of B7-H6 in HepG2 and SMMC-7721 cells significantly attenuated cell proliferation as well as cell migration and invasion.