Expression of gap junction protein connexin32 in chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma

Background. The gap junction (GJ) plays important roles in the maintenance of tissue homeostasis, the control of cell growth and differentiation, and the prevention of experimental hepatocarcinogenesis. In this study, we examined the relationship between the expression of the GJ protein connexin (Cx) 32 in 24 human hepatocellular carcinomas (HCCs) and 29 non-carcinomatous liver specimens (NCLs) of 31 patients. Methods. An immunohistochemical study of Cx32 was done in 24 HCCs and 29 NCLs from 31 patients who had undergone hepatic resection. Results. The Cx32 expression decreased gradually as the disease progressed to cirrhosis and HCC. In all Cx32 positive HCCs, the expression was mostly recognized in cytoplasm, not only on the cell membrane. This internalization of Cx32 was also recognized in liver specimens showing hepatitis and cirrhosis, although it was less frequent than in the HCCs. Conclusions. These findings suggest the possibility that changes in both the amount and the distribution of Cx32 may be implicated in human hepatocarcinogenesis.