Role of Hbx and Androgen Receptor in Regulating Senp1/Stemess-Related Properties in Hbv-Related Hcc and Its Clinical Impact

Hepatocellular carcinoma (HCC) is the fifth most common cancer in men and the ninth in women worldwide. Given the shortage of effective targeted therapy for this cancer, HCC ranked the second leading cause of cancer mortality throughout the world in 2012. Sex disparity of HBV infection has long been observed in the patients with chronic HBV infection and has been delineated in HBV transgenic animal models. The impact of gender disparity is of particular importance for hepatitis B (HBV)-induced hepatocarcinogenesis. The regulatory effect of androgen on HBV gene expression was proved to be mediated by AR as AR gene knockdown diminished HBV surface (HBsAg) protein production in transgenic male mice. The clinical observations regarding sex disparity of HBV infection was attributed by direct cis-regulation of AR on HBV transcription as binding of AR to the two androgen responsive elements (ARE) located in HBV enhancer I resulted in the enhanced expression of overall HBV transcripts. Since elevated serum HBV DNA level is a strong independent risk factor for HCC development, this positive cis-regulation of AR on HBV transcription may partially explain the gender specific difference in the incidence of HCC. In addition to the indirect effect of AR on accelerating HBV transcription, AR can also cooperate with the downstream target gene protein HBx with a positive feedback manner to promote hepatocarcinogenesis. However, the role of HBx and AR in re-expression of cancer stemness-related properties in cancer tissues still remains largely unknown. Our previous report revealed that the expression of pluripotent transcription factor OCT4 occurred preferentially in HBV-HCC (2015 Clin Cancer Res); furthermore, we also demonstrated that SENP1 -controlled sumoylation regulates the OCT4 protein stability and chemotherapeutic sensitivity of human testicular germ cell tumors (2012 Cancer Res). Additionally, our preliminary clinical results showed the concurrent high expressions of AR, SENP1, and OCT4 occur particularly in HBV-HCC, and HCC patients with both higher levels of AR and SENP1 showed significant poor prognosis and early tumor recurrence. Together with these results, we then hypothesize that the hepatocarcinogenesis effect of HBx and AR is regulated by SENP1-mediated stemness properties expression. Our proposal aims to unravel the hypothesized role of HBx/AR in SENP1-mediated expressions of stemness-related properties (such as OCT4 expression) in HBV-HCC. Three specific aims will be addressed as listed: Aim 1: To examine the role HBx in expressions of phospho-AR/AR, SENP 1, and stemness-related properties in HBV-HCC using a HBx-GFP overexpression system in Huh7/HepG2 cells (comparing with GFP-Huh7/HepG2 control cell model) Aim 2: To examine the role of AR activation in HBx-induced expressions of SENP1 and stemness-related properties in HBx-GFP Huh7/HepG2 cells in vitro and vivo Aim 3: To verify the clinical association of tissue SENP1, AR, nuclear phospho-AR, OCT4 expression levels, and serum testosterone with early recurrence of HCC patients Key words: Pluripotent transcription factor OCT4、SENP1、Hepatitis B virus (HBV) X protein、 Androgen receptor、Early recurrence, Hepatocellular carcinoma