[The expression of hepatitis B virus X protein and cyclooxygenase-2 in hepatitis B virus-related hepatocellular carcinoma: correlation with microangiogenesis and metastasis, and what is the possible mechanism].

OBJECTIVE: To investigate the expression of HBx and COX-2 in hepatitis B virus-related hepatocellular carcinoma, and Its correlation with microangiogenesis and metastasis, and possible mechanism.

METHODS: Immunohistochemistry was used to detect the expression of hepatitis B virus X, cyclooxygenase-2 and CD34 in hepatitis B virus related hepatic carcinoma and 22 non-HBV related hepatic carcinoma tissues. The expression of hepatitis B virus x protein and cyclooxygenase-2 in hepatitis B virus-related hepatocellular carcinoma correlated with microangiogenesis and metastasis was tested by Spearman correlation analysis. The expression of COX-2 in HepG2-X was detected by Western blot and RT-PCR. PGE2 was detected by ELISA in clear supernatant liquid of HepG2-X. Trypan blue exclusion was performed to examine the inhibitory effects of COX-2 selective inhibitor (celecoxib).

RESULTS: In Hepatitis B carcinoma tissue, HBx and COX-2 were expressed at high level. The positive rate of COX-2 expression was 88.87% (55/62) in HBx positive expression group, which was significantly higher than that of the positive expression 31.82% (7/22, x2=27.188, P<0.01) in HBx negative expression group and 40.91% (9/22, x2=20.453, P<0.01) in non-HBV related hepatic carcinoma tissues, but it had no statistical difference (x2=0.393, P=0.531) between the HBx negative expression group and non-HBV related hepatic carcinoma tissue group. The expressions of HBx and COX-2 in metastasis group were higher than that in non-metastasis group (P<0.01), MVD in HBx or COX-2 positive expression group was significantly higher than that in negative expression group and non-HBV related hepatic carcinoma tissues (P is less than 0.01). MVD with metastasis was higher than that without metastasis (P<0.01) and MVD with portal vein invasion was higher than that without invasion (P<0.05). Spearman correlation analysis showed that the expression of COX-2 was significantly correlated with the expression of HBx (Rs=0.568, P<0.01). Celecoxib suppressed the growth of both cells in a dose-dependent manner. HepG2-X was significantly susceptible to celecoxib as compared to the HepG2-PC cells. COX-2 protein and mRNA were upregulated in HepG2-X cells than in HepG2-PC. Moreover, PGE2 was upregulated in clear supernatant liquid of HepG2-X than in HepG2-PC.

CONCLUSION: The expressions of HBx and COX-2 were higher in HBV-related hepatocellular carcinoma. COX-2 was significantly correlated with HBx in HCC and it could be a key factor involved in HBx contributed hepatocellular carcinoma's microangiogenesis and metastasis. The possible mechanism of the dual effects might be through HBx, COX-2 and PGE2 pathways in infiltration involved metastasis and microangiogenesis involved metastasis.