Role of sex steroid receptors in pathobiology of hepatocellular carcinoma

The striking gender disparity observed in the incidence of hepatocellular carcinoma (HCC) suggests an important role of sex hormones in HCC pathogenesis. Though the studies began as early as in 1980s,the precise role of sex hormones and the significance of their receptors in HCC still remain poorly understood and perhaps contribute to current controversies about the potential use of hormonal therapy in HCC. A comprehensive review of the existing literature revealed several shortcomings associated with the studies on estrogen receptor (ER) and androgen receptor (AR) in normal liver and HCC. These shortcomings include the use of less sensitive receptor ligand binding assays and immunohistochemistry studies for ERα alone until 1996 when ERβ isoform was identified. The animal models of HCC utilized for studies were primarily based on chemical-induced hepatocarcinogenesis with less similarity to virus-induced HCC pathogenesis. However,recent in vitro studies in hepatoma cells provide newer insights for hormonal regulation of key cellular processes including interaction of ER and AR with viral proteins. In light of the above facts,there is an urgent need for a detailed investigation of sex hormones and their receptors in normal liver and HCC. In this review,we systematically present the information currently available on androgens,estrogens and their receptors in normal liver and HCC obtained from in vitro,in vivo experimental models and clinical studies. This information will direct future basic and clinical research to bridge the gap in knowledge to explore the therapeutic potential of hormonal therapy in HCC.

Estrogen receptor expression in chronic hepatitis C and hepatocellular carcinoma pathogenesis

AIM To investigate gender-specific liver estrogen receptor(ER) expression in normal subjects and patients with hepatitis C virus(HCV)-related cirrhosis and hepatocellular carcinoma(HCC).METHODS Liver tissues from normal donors and patients diagnosed with HCV-related cirrhosis and HCV-related HCC were obtained from the NIH Liver Tissue and Cell Distribution System. The expression of ER subtypes, ERα and ERβ, were evaluated by Western blotting and real-time RT-PCR. The subcellular distribution of ERα and ERβ was further determined in nuclear and cytoplasmic tissue lysates along with the expression ofinflammatory [activated NF-κB and IκB-kinase(IKK)] and oncogenic(cyclin D1) markers by Western blotting and immunohistochemistry. The expression of ERα and ERβ was correlated with the expression of activated NF-κB, activated IKK and cyclin D1 by Spearman's correlation. RESULTS Both ER subtypes were expressed in normal livers but male livers showed significantly higher expression of ERα than females(P < 0.05). We observed significantly higher m RNA expression of ERα in HCV-related HCC liver tissues as compared to normals(P < 0.05) and ERβ in livers of HCV-related cirrhosis and HCV-related HCC subjects(P < 0.05). At the protein level, there was a significantly higher expression of nuclear ERα in livers of HCV-related HCC patients and nuclear ERβ in HCV-related cirrhosis patients as compared to normals(P < 0.05). Furthermore, we observed a significantly higher expression of phosphorylated NF-κB and cyclin D1 in diseased livers(P < 0.05). There was a positive correlation between the expression of nuclear ER subtypes and nuclear cyclin D1 and a negative correlation between cytoplasmic ER subtypes and cytoplasmic phosphorylated IKK in HCV-related HCC livers. These findings suggest that dysregulated expression of ER subtypes following chronic HCVinfection may contribute to the progression of HCVrelated cirrhosis to HCV-related HCC.CONCLUSION Gender differences were observed in ERα expression in normal livers. Alterations in ER subtype expression observed in diseased livers may influence genderrelated disparity in HCV-related pathogenesis.