The Expression Of EpCAM In Hepatocellular Carcinoma And Its Role In Metastasis

Objectives(1)To investigate the expression of EpCAM in hepatocellular carcinoma and the relationship of expression intensity with the clinicopathologic characteristics of hepatocellular carcinoma, especially the relationship with metastasis.(2)To examine the expression of EpCAM in hepatocellular carcinoma cells, and to choose the suitabale cell lines for further analysis of metastatic mechanisms of hepatocellular carcinoma.Methods(1)The subcellular location and expression of EpCAM in hepatocellular carcinoma, including metastatic and non-metastatic cases were determined by immunohistochemistry analysis.(2)Semiquantitative RT-PCR and Western blot were applied to detect the EpCAM mRNA and protein level in hepatocellular carcinoma cell lines.Results1. EpCAM was over-expressed in hepatocellular carcinoma tissues and cell lines, especially in metastatic hepatocellular carcinoma. Immunohistochemistry carried out on 106 paraffin-embedded hepatocellular carcinoma sections showed that EpCAM was predominantly expressed in the membrane of liver cells and occasionally diffused into cytoplasm. In hepatocellular carcinoma tissues,45.3% (48of 106 cases) was overexpressed. Recurrences were found in 54 patients during 3 years follow-up, Positive expression rate 70.4% (38/54) of EpCAM in hepatocellular carcinoma with recurrence or metastasis is higher than those without metastasis hepatocellular, expression of EpCAM positive rate of 19.2%(10/52). Liver metastasis EpCAM immunohistochemistry score was 7.11±1.32, also significantly higher than those without metastasis of liver cancer immunohistochemical staining score 4.63±2.72 (P <0.05.) Further analysis of EpCAM expression and clinicopathological features of the patients revealed a negative association of its expression with sex, age, HBsAg, AFP, liver cirrhosis,Edmonson stage,tumor vascular invasion, preoperative Child-Pugh classification P>0.05). However,significant difference was found in tumor size, shape of tumor and Tumor capsule formation (present/absent) among the two groups(P<0.05). Kaplan-Meier analysis demonstrated HBsAg,HCV,AFP,liver cirrhosis, tumor diameter, shape of tumor, Edmonson classification, Tumor capsule formation (present/absent), tumor vascular invasion and EpCAM expression were significant factors influencing the disease-free survival of HCC patients(P<0.05). COX regrssion showed HBsAg, HCV, AFP, liver cirrhosis, tumor diameter, tumor vascular invasion and EpCAM expression were significant risk factors influencing the disease-free survival of HCC patients(P<0.05). Logistic regression indicated that HBsAg, HCV, AFP, liver cirrhosis, tumor diameter, tumor vascular invasion and EpCAM experssion were risk factors of tumor metastasis and recurrence (P<0.05).2,Semi-quantitative RT-PCR and Western blot analysis on hepatocellular carcinoma cell lines, MHCC 97L,SMMC-7721,QGY-7703,Hep3B and HepG2 revealed that EpCAM was highly-expressed in both of mRNA and protein levels in Hep3B and HepG2 cell lines.ConclusionsEpCAM is highly expressed in some hepatocellular carcinoma tissues, which is an independent risk factor in predicting the metastasis and recurrence of HCC. The present work gives the convincing evidence of EpCAM as the oncogene in HCC and paves the way for EpCAM as a novel candidate of diagnosis and treatment of HCC metastasis.