Expression Of CBX8 In Hepatocellular Carcinoma And Its Effects On Proliferation,Invasion And Cell Cycle Of Hepatocellular Carcinoma Cell Line SMMC-7721

Objective To preliminarily investigate the role and significance of CBX8 in the tumorigenesis and development of hepatocellular carcinoma,by detecting the expression of CBX8 mRNA and protein in hepatocellular carcinoma tissues and the effects of CBX8 on proliferation,invasion and cell cycle in hepatocellular carcinoma cell line SMMC-7721.Methods Quantitative real-time polymerase chain reaction(qRT-PCR)and western blot were used to respectively explore the mRNA and protein of CBX8 in 15 pairs of fresh tissue including hepatocellular carcinoma surgical samples and the corresponding adjacent normal tissues.Tissue microarray with immunohistochemistry was performed to examine the expression of CBX8 protain in 120 cases of hepatocellular carcinoma and the corresponding adjacent normal tissue specimens and then analyzed the relation between the expression of CBX8 in hepatocellular carcinoma and tumorigenesis and clinicopathologic characteristics.Transiently transfected the small interfering RNA and overexpression plasmid respectively in SMMC-7721 cells and measured the ability of proliferation and invasion in SMMC-7721 cell lines by MTT,plate clone formation assay and transwell assay.The effect of CBX8 on cell cycle of SMMC-7721 cells was detected by cell synchronization and flow cytometry.Results The up-regulated expression of CBX8 mRNA was detected in 13(13/15)cases of HCC by qRT-PCR,and the difference in 15 pairs of fresh tissue was significant(t=2.742,P<0.05).Increased expression of CBX8 protein was detected by western blot in 11(11/15)cases of HCC,and the difference in 15 pairs of fresh tissue was also significant(t=2.686,P<0.05).The expression was observed in 100 cases(83.33%)of hepatocellular carcinoma surgical specimen,46 cases(38.33%)of the corresponding adjacent normal tissue specimens.The result of tissue microarray with immunohistochemistry showed that expression level of CBX8 in hepatocellular carcinoma and corresponding adjacent normal tissue specimens were different,and the difference was significant(Z=-8.072,P(27)0.05).What's more,the expression of CBX8 in hepatocellular carcinoma was associated with hepatitis B virus surface antigen(HBsAg),diameter of tumor,capsular invasion and TNM stage(c2=10.900?4.043?46.570?8.374,P(27)0.05).The proliferation,clonal formation rate,migration and invasion ability of SMMC-7721 cells were decreased after the knockdown of CBX8,and the difference was statistically significant(F=9.395?24.300?71.180?8.745?63.700?9.044,P <0.05).The result was opposite after CBX8 was overexpressed,and the difference was statistically significant(F=7.177?36.100?24.680?9.045?7.037?6.525,P <0.05).By detecting the cell cycle,we found that the percentage of G1 phase cells in the experimental group was significantly increased after the knockdown of CBX8 and the proportion of S phase cells decreased,the differences were statistically significant(t=3.170?3.269,P <0.05).What's more,the proportion of G1 phase cells in the experimental group was significantly decreased after CBX8 overexpression and the percentage of S phase cells increased,the differences were statistically significant(t=2.884?4.443,P <0.05).Conclusion CBX8 is significantly overexpressed in hepatocellular carcinoma and plays an important role in the tumorigenesis and progression of hepatocellular carcinoma.CBX8 can promote the proliferation,migration and invasion of SMMC-7721 cells and may affect the cell cycle of SMMC-7721 by regulating G1/S transformation.CBX8 act as oncogene in the occurrence and development of hepatocellular carcinoma.