OBJECTIVETo investigate the effect of the COX-2 gene on the oncogenesis and development of the hepatocellular carcinoma and the influence of COX-2 gene on the expression of P-gp protein.

METHODFifty-two pieces of the hepatocellular carcinoma samples and 20 cases of normal liver samples were collected from the patients operated from October 2003 to June 2005. RT-PCR and immunohistochemistry staining were employed to detect the COX-2 mRNA as well as P-gp protein in the normal liver tissues and the carcinoma tissues. Meanwhile, the expression of the mdr 1 mRNA in the carcinoma tissues was also determined and the correlation between the expressions of the COX-2 and P-gp was investigated.

RESULTSNo expression of the COX-2 in the normal liver tissue was detected. The positive expression of COX-2 in the low and middle differentiated carcinoma was elevated significantly as compared with that in the high differentiated carcinoma tissue (x2 = 6.80, P less than 0.01). The positive expression of the COX-2 in the HBSAg (+) carcinoma tissue was significantly higher as compared with that in the HBSAg (-) carcinoma (x2 = 4.70, P less than 0.05), and the carcinoma in combination with cirrhosis also showed significantly higher in expression of COX-2 than the carcinoma without cirrhosis (x2 = 7.51, P less than 0.01). The mdr1 mRNA was found both expressed in the normal and carcinoma tissues. The expression of COX-2 mRNA was found in the carcinoma, but not found in the normal tissues. The COX-2 mRNA and mdr1 mRNA was found both expressed in the normal and carcinoma tissues. The correlation coefficient between COX-2 and mdr1 mRNA was 0.563 ( P less than 0.01).

CONCLUSIONThe results indicated that Cox-2 gene might involved in the multidrug resistance of the hepatocellular carcinoma mediated by P-gp.