miR-22 Promotes HBV-Related Hepatocellular Carcinoma Development in Males

Purpose: Previous reports have shown that IL-1 alpha-MyD88-IL- 6 signaling is essential in promoting hepatocellular carcinoma (HCC) development in a diethylnitrosamine (DEN)- induced mouse model. We aimed to determine whether interleukin (IL)-1 alpha regulates HCC development in humans. Methods: HBV-associated HCC tissue, corresponding adjacent tissue, and normal tissue samples were obtained from 80 male and 36 female patients. IL-1 alpha, ER alpha, IL-6, and MyD88 were quantified by using real-time PCR and Western blot. Stem-loop PCR was used to quantify miR-22 expression. Luciferase reporter assays were used to study transcriptional regulation. Results: IL-1 alpha was highly expressed in male tumor adjacent tissue compared with normal tissue (P = 0.025); however, this was not the case for female subjects. A linear relationship was observed between increased IL-1 alpha and decreased ER alpha expression in male tumor adjacent tissue (r = - 0.616, P = 0.004). Our results also indicated that estrogen (E2) was suppressed upon IL-1 alpha secretion in ER alpha-overexpressed HCC cells. We detected high expression of miR-22 in male tumor adjacent tissue compared with controls (P = 0.027); furthermore, we showed that miR-22 downregulates ER alpha transcription by targeting the 3'- untranslated region. In the DEN-induced model, IL-1 alpha was highly expressed in sprouting tumors and gradually decreased in conjunction with HCC development. Conclusion: Overexpression of miR-22 in male tumor adjacent tissue was associated with down-regulated ER alpha expression, potentially by attenuating the protective effect of estrogen and causing increased IL-1 alpha expression. These results may explain the high incidence of HBV-associated HCC in the male population. Clin Cancer Res; 17(17); 5593-603. (C)2011 AACR.