Expression And Significance Of EZH2 Gene In Hepatocellular Carcinoma

Background and object: Hepatocellular carcinoma (HCC) is one of the highest malignant tumors in china. Many genetic mutations are the major factors of which induced the HCC. Enhancer of zeste homologue 2(EZH2) is homeotic gene,a member of PcG protein family. Polyeomb group (PcG) proteins,with the counteracting Trithorax group(TrxG)proteins,establish a form of cellular memory by regulating gene expression in a heritable fashion. Dysregulation of the transcriptional memory maintenance system can lead to disastrous consequences , ranging from developmental defects to cancer. Recently, accumulating evidence indicates that EZH2 overexpresses in the aggressive human cancers. Therefore, the present research investigates the role of EZH2 in the HCC.Materials and Methods: We had collected 42 cases of HCC tissues which had been diagnosised by Dr of the Department of Pathology of the GuangXi Medical University from 2005,12-2006,9, 9 cases of adjacent liver tissues from hemangiomas of liver(as control group).We detected the expression of mRNA of the EZH2 by reverse transcription polymerase chain reaction(RT-PCR) and the expression of protein of the EZH2 by immunohistochemical method.The results were used to analyze the relationship between the expression of EZH2 in HCC and informations of pathology and clinic (including hepatitis B virus, pathological stage, the level of serum alpha-fetoprotein (AFP), the diameter of tumor, the intravenous tumor thrombus and the presence of metastasis).Result: 1.RT-PCR was used to detect the expression of EZH2 in 42 cases. The positive rates of EZH2 mRNA in HCC were 61.9% (26/42), and 28.6% (12/42) in their adjacent liver tissues and 22.2% (2/9) in the control group, respectively(P<0.01).The positive rate of EZH2 mRNA in HCC compared with the HCC surrounding tissue and the normal tissue of liver, the differences are remarkable(P<0.05). The difference between the HCC surrounding tissue and the normal tissue of liver is not remarkable(P>0.05).The positive rate of EZH2 mRNA in HCC was significantly correlated with the pathological stage(P<0.05), but not correlated with the hepatitis B virus, the intravenous tumor thrombus ,the presence of metastasis, the level of serum AFP and diameter of tumor(P>0.05).2. Immunohistochemistry revealed that, among 42 cases,the positive rates of EZH2 protein were 59.5%(25/42) in HCC, 21.4%(9/42) in their adjacent liver tissues, and 22.2%(2/9) in the control group,respectively(P<0.01). The positive rate of EZH2 mRNA in HCC compared with the HCC surrounding tissue and the normal tissue of liver, the differences are remarkable(P<0.05). The difference between the HCC surrounding tissue and the normal tissue of liver is not remarkable(P>0.05). The positive rate of EZH2 protein in HCC is not correlated with the hepatitis B virus, the pathological stage, the intravenous thrombus ,the presence of metastasis, the level of serum AFP and diameter of tumor(P>0.05).Conclusion: The level of expression of EZH2 in HCC is fairly high. The positive rate of EZH2 mRNA in HCC was significantly correlated with the pathological stage, and might be used as markers of prognosis of HCC in the degree of malignancy.