Possible involvement of androgen receptor alterations in hepatocarcinogenesis

Influence of Sex in the Development of Liver Diseases

The liver is a sexually dimorphic organ. Sex differences in prevalence, progression, prognosis, and treatment prevail in most liver diseases, and the mechanism of how liver diseases act differently among male versus female patients has not been fully elucidated. Biological sex differences in normal physiology and disease arise principally from sex hormones and/or sex chromosomes. Sex hormones contribute to the development and progression of most liver diseases, with estrogen- and androgen-mediated signaling pathways mechanistically involved. In addition, genetic factors in sex chromosomes have recently been found to contribute to the sex disparity of many liver diseases, which might explain, to some extent, the difference in gene expression pattern, immune response, and xenobiotic metabolism between men and women. Although increasing evidence suggests that sex is one of the most important modulators of disease prevalence and outcomes, at present, basic and clinical studies have long been sex unbalanced, with female subjects underestimated. As such, this review focuses on sex disparities of liver diseases and summarizes the current understanding of sex-specific mechanisms, including sex hormones, sex chromosomes, etc. We anticipate that understanding sex-specific pathogenesis will aid in promoting personalized therapies for liver disease among male versus female patients.

Premenopausal Syndrome and NAFLD: A New Approach Based on Gender Medicine

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial condition that affects 25% of the world's population. There is a clear difference in both geographical distribution and sex in childbearing age. These differences are reduced when women become older and senescence begins. The factors that affect the likelihood of developing NAFLD in a premenopausal woman are an imbalance of sex hormones (especially in estradiol and androgen), microbiome dysregulation, insulin resistance, early menarche, the length of time that the woman breastfeeds for and polycystic ovarian syndrome (PCOS). The aim of this review is to identify various physical ailments that may not appear to be serious to young women but that then affect the onset of NAFLD in perimenopause and can degenerate into NASH. These conditions should also be considered in future clinical management, as well as in research opportunities, in order to customize the monitoring and treatment of NAFLD, considering gender medicine for those women who had early metabolic symptoms that were not considered to be significant at the time.

Toward improving androgen receptor-targeted therapies in male-dominant hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the predominant form of liver cancer and a leading cause of cancer deaths worldwide. HCC is a male-dominant cancer with a male:female ratio of up to 7:1. The androgen receptor (AR) is the male hormone receptor known as a major oncogenic driver of prostate cancer. Although AR has been linked to the sexual dimorphism of HCC, clinical trials with AR-targeted agents failed to generate survival benefits. Recent studies provide new insights into the role of AR in liver tumorigenesis and therapeutic responses. Herein, we review current understanding of AR signaling in HCC and feedback mechanisms that limit response to AR blockade. New AR-targeting strategies that might improve outcomes in HCC therapies are also discussed.

Transcriptionally Active Androgen Receptor Splice Variants Promote Hepatocellular Carcinoma Progression

Owing to the marked sexual dimorphism of hepatocellular carcinoma (HCC), sex hormone receptor signaling has been implicated in numerous aspects of liver cancer pathogenesis. We sought to reconcile the clear contribution of androgen receptor (AR) activity that has been established in preclinical models of HCC with the clinical failure of AR antagonists in patients with advanced HCC by evaluating potential resistance mechanisms to AR-targeted therapy. The AR locus was interrogated for resistance-causing genomic modifications using publicly available primary HCC datasets (1,019 samples). Analysis of HCC tumor and cell line RNA-seq data revealed enriched expression of constitutively active, treatment-refractory AR splice variants (AR-SV). HCC cell lines expressed C-terminal-truncated AR-SV; 28 primary HCC samples abundantly expressed AR-SV. Low molecular weight AR species were nuclear localized and constitutively active. Furthermore, AR/AR-SV signaling promoted AR-mediated HCC cell progression and conferred resistance to AR antagonists. Ligand-dependent and -independent AR signaling mediated HCC epithelial-to-mesenchymal transition by regulating the transcription factor SLUG. These data suggest that AR-SV expression in HCC drives HCC progression and resistance to traditional AR antagonists. Novel therapeutic approaches that successfully target AR-SVs may be therapeutically beneficial for HCC. SIGNIFICANCE: Treatment-refractory, constitutively active androgen receptor splice variants promote hepatocellular carcinoma progression by regulating the epithelial-to-mesenchymal transition pathway.

Recent advances in the molecular mechanism of sex disparity in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is more frequently observed and aggressive in men compared with women. Increasing evidence demonstrates that the sex disparity appears to be mediated by the stimulatory effects of androgens and the protective effects of estrogen in the development and progression of HCC. In the past few decades, studies on the sex difference of HCC mainly focused on the effect of sex hormones on the transactivation of hepatitis B virus X protein and the release of inflammatory cytokines, and these studies have further intensified in recent years. Sex hormones are also involved in genetic alterations and DNA damage repair in hepatocytes through binding to their specific cellular receptors and affecting the corresponding signaling pathways. Furthermore, the theory of sex chromosomes participating in HCC has been considered. The present review discussed the recent advances in the molecular mechanisms of sex disparity in HCC, with the aim of improving the understanding of the underlying critical factors and exploring more effective methods for the prevention and treatment of HCC.

Bcl-2 expression is a poor predictor for hepatocellular carcinoma prognosis of andropause-age patients

OBJECTIVE

The expression of B-cell lymphoma 2 (Bcl-2) seems to be influenced by the endocrine environment. Numerous reports demonstrate the diverse expression of Bcl-2 family members under sex steroid regulation. With the exception of estrogen-related tumors, androgen-related tumors have shown their characteristics in Bcl-2 expression. In this study, the status of Bcl-2 expression in male hepatocellular carcinoma (HCC) patients was examined to verify the high incidence of HCC in males.

METHODS

Tumor tissue microarray was used to examine Bcl-2 expression levels in 374 HCC cases including 306 males and 68 females. Kaplan-Meier method, log-rank test, and Cox proportional hazards model were applied to investigate the predictive value of Bcl-2 in HCC patients.

RESULTS

Immunohistochemistry analysis showed that male patients with higher Bcl-2 levels had significantly longer median survival time and recurrence time than those with lower levels. However, no significant differences in outcomes were found between different Bcl-2 levels in female patients. When the male patients were stratified into several age points, the level of Bcl-2 expression showed poorer predictive efficiency in the 45-49 and 55-60 age groups in andropause-age patients compared with other age groups. Bcl-2 was an independent prognostic factor for both overall survival (P < 0.0001) and recurrence time (P = 0.0001) in male patients. After excluding male patients in the 45-60 age group, the predictive efficiency was enhanced (n = 147, OS, P = 0.0002, TTR, P < 0.0001).

CONCLUSIONS

Bcl-2 expression is an independent predictor of survival and recurrence in male HCC. Bcl-2 levels may also be regulated by androgens or androgen receptors in male HCC patients. Bcl-2 levels change and exhibit poor predictive efficiency when androgen levels vary dramatically (andropause age).

Androgen receptor in hepatocarcinogenesis: Recent developments and perspectives

Previous studies have indicated that males are at a higher risk of developing hepatocellular carcinoma (HCC) compared with females. Identifying the factors that cause this gender-specific difference in the incidence of HCC has long been considered important for revealing the molecular mechanisms involved in hepatocarcinogenesis. Given the unprecedented tools that are now available for molecular research, genetic studies have established that the androgen receptor (AR) may be partly responsible for gender disparity in HCC. AR has a dual role, promoting HCC initiation and development, as well as suppressing HCC metastasis. The present review provides an overview of the involvement of AR signaling in HCC. The review highlighted important studies, examples of the direct AR transcriptional target genes involved in HCC and novel theories concerning the conventional concept, suggesting that targeting the AR, rather than the androgen, may provide an improved therapeutic approach for the treatment of HCC.

Hepatic androgen receptor suppresses hepatocellular carcinoma metastasis through modulation of cell migration and anoikis

Early reports suggested androgen/androgen receptor (AR) signals promote hepatocarcinogenesis. However, all antiandrogen clinical trials failed in advanced hepatocellular carcinoma (HCC) without reasonable explanations. We examined AR functions in HCC cancer metastasis in this study. We examined hepatic AR roles in HCC metastasis by comparing liver hepatocyte AR knockout and wildtype in a carcinogen-induced HCC mouse model. We examined tumor histology, cancer metastatic risks, and cancer survival in vivo, as well as cell anoikis and migration using primary hepatic tumor culture in vitro. We also examined therapeutic potentials of AR expression combined with the molecular targeting agent sorafenib in an HCC metastasis mouse model. We found a novel cancer phenotype in which mice lacking hepatic AR developed more undifferentiated tumors and larger tumor size at the metastatic stage. These mice also died earlier with increased lung metastasis, suggesting that hepatic AR may play dual yet opposite roles to promote HCC initiation but suppress HCC metastasis. Mechanistic dissection found that hepatic AR could enhance anoikis and suppress migration of HCC cells by way of suppression of p38 phosphorylation/activation and the nuclear factor kappa B (NF-κB)/matrix metallopeptidase 9 (MMP9) pathway, respectively. In addition, the in vivo preclinical trials concluded that a combination therapy of increased AR expression and reduced multiple-kinase inhibitor (sorafenib) exhibited better therapeutic efficacy.

CONCLUSION

Our study demonstrates that AR could orchestrate intrahepatic signaling hierarchies and cellular behaviors, consequently affect HCC progression. Results from combination therapy shed light on developing new therapeutic paradigms for battling HCC at later metastatic stages.

From chronic liver disorders to hepatocellular carcinoma: Molecular and genetic pathways

Hepatocarcinogenesis is a process attributed to progressive genomic changes that alter the hepatocellular phenotype producing cellular intermediates that evolve into hepatocellular carcinoma (HCC). During the preneoplastic phase, the liver is often the site of chronic hepatitis and/or cirrhosis, and these conditions induce liver regeneration with accelerated hepatocyte cycling in an organ that is otherwise proliferatively at rest. Hepatocyte regeneration is accelerated by upregulation of mitogenic pathways involving molecular and genetic mechanisms. Hepatic growth factors, inhibitors and triggers may also play a role. This process leads to the production of monoclonal populations of aberrant and dysplastic hepatocytes that have telomerase re-expression, microsatellite instability, and occasionally structural aberrations in genes and chromosomes. Development of dysplastic hepatocytes in foci and nodules and the emergence of HCC are associated with the accumulation of irreversible structural alterations in genes and chromosomes even if the genomic basis of the malignant phenotype is largely heterogeneous. Therefore, a malignant hepatocyte phenotype may be produced by changes in genes acting through different regulatory pathways, thus producing several molecular variants of HCC. On these bases, a key point for future research will be to determine whether the deletions are specific, due to particular loci in the minimally deleted regions of affected chromosome arms, or whether they are non-specific with loss of large portions of chromosomes or entire chromosome arms leading to passive deletion of loci. The final aim is the possibility of identifying a step where carcinogenetic processes could be terminated.