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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The molecular mechanism of striking higher prevalence of hepatocellular carcinoma (HCC) in male subjects has not yet been fully elucidated. Here, we report that androgen receptor (AR) is differentially expressed in different HCC cell lines. AR agonist dihydrotestosterone (DHT) enhances HCC cell growth and apoptotic resistance. Antagonist flutamide (FLU) blocks the effects of DHT on the HCC cell lines. Paternally expressed gene 10 (PEG10) is expressed in HCC cell lines at substantial high level. Using small interfering RNAs against AR and PEG10 in AR- and PEG10-expressing BEL-7404 hepatoma cells and HuH7 hepatoma cells (HuH7) cells, and AR-transfection technique in AR-lacking and PEG10-expressing HepG2 cells, we have confirmed that through upregulation and activation of PEG10, DHT enhances HCC cell growth and apoptotic resistance. We have further demonstrated that DHT upregulates expression of human telomerase reverse transcriptase (hTERT) in HCC cell lines in a PEG10-dependent manner. Moreover, AR directly interacts in vivo with androgen-responsive elements in the regions of promoter and exon 2 of PEG10 gene in HCC cell lines. DHT promotes the hepatoma formation in vivo nude mice through PEG10 activation. AR antagonists (FLU and valproate) inhibit the hepatoma formation. These findings suggest that PEG10 plays an essential role in hepatocarcinogenesis. The PEG10 inhibition can be a novel approach for therapy of HCC.
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PMID:Androgen activates PEG10 to promote carcinogenesis in hepatic cancer cells. 2167 54

Hepatocellular carcinoma (HCC) is a male-predominant cancer associated with chronic hepatitis. Like human viral hepatitis, murine Helicobacter hepaticus infection produces inflammation and HCC with a masculine bias. We used this model to identify potential mechanisms of male HCC predisposition. Male weanling A/JCr mice (n = 67) were gavaged with H. hepaticus or vehicle. At 1 year, mice were distributed into four groups: surgical castration, chemical castration, castration followed by dihydrotestosterone supplementation, or sexually intact controls. Responses to infection were compared with IFN-gamma challenge alone. At 21 months, there was no significant difference in hepatitis between groups. Neither castration nor androgen receptor agonism altered tumor incidence. Infected mice with severe, but not mild, disease exhibited a mosaic of alterations to sexually dimorphic genes and microsomal long-chain fatty acids. By microarray, tumorigenic hepatitis was strongly associated with liver-gender disruption, defined as the loss of a gender-identifying hepatic molecular signature. IFN-gamma alone produced similar changes, demonstrating a role for proinflammatory cytokines in this process. In conclusion, hepatocarcinogenesis in male mice with chronic hepatitis is maturationally imprinted and androgen-independent. Proinflammatory cytokines may promote HCC in a male-predominant fashion due to high sensitivity of the masculinized liver to loss of sex-specific transcriptional balance. Liver-gender disruption has pleiotropic implications for hepatic enzyme activity, lipid processing, nuclear receptor activation, apoptosis, and proliferation. We propose a multistep model linking chronic hepatitis to liver cancer through cytokine-mediated derangement of gender-specific cellular metabolism. This model introduces a novel mechanism of inflammation-associated carcinogenesis consistent with male-predominant HCC risk.
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PMID:Hepatocellular carcinoma associated with liver-gender disruption in male mice. 1808 82

Hepatitis B virus (HBV), the leading cause of human hepatocellular carcinoma, is especially virulent in males infected at an early age. Likewise, the murine liver carcinogen Helicobacter hepaticus is most pathogenic in male mice infected before puberty. We used this model to investigate the influence of male sex hormone signaling on infectious hepatitis. Male A/JCr mice were infected with H. hepaticus or vehicle at 4 weeks and randomized into surgical and pharmacologic treatment groups. Interruption of androgen pathways was confirmed by hormone measurements, histopathology, and liver gene and Cyp4a protein expression. Castrated males and those receiving the competitive androgen receptor antagonist flutamide had significantly less severe hepatitis as determined by histologic activity index than intact controls at 4 months. Importantly, the powerful androgen receptor agonist dihydrotestosterone did not promote hepatitis. No effect on hepatitis was evident in males treated with the 5alpha-reductase inhibitor dutasteride, the peroxisome proliferator-activated receptor-alpha agonist bezafibrate, or the nonsteroidal anti-inflammatory drug flufenamic acid. Consistent with previous observations of hepatitis-associated liver-gender disruption, transcriptional alterations involved both feminine (cytochrome P450 4a14) and masculine (cytochrome P450 4a12 and trefoil factor 3) genes, as well gender-neutral (H19 fetal liver mRNA, lipocalin 2, and ubiquitin D) genes. Hepatitis was associated with increased unsaturated C(18) long-chain fatty acids (oleic acid and linoleic acid) relative to saturated stearic acid. Our results indicate that certain forms of androgen interruption can inhibit H. hepaticus-induced hepatitis in young male mice, whereas androgen receptor agonism does not worsen disease. This raises the possibility of targeted hormonal therapy in young male patients with childhood-acquired HBV.
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PMID:Sex hormone influence on hepatitis in young male A/JCr mice infected with Helicobacter hepaticus. 1855 27

Hepatitis C virus (HCV) infection is frequently associated with the development of hepatocellular carcinoma (HCC), which is one of the male-dominant diseases. Androgen signaling in liver may be related to carcinogenesis. In this study, we investigated whether HCV proteins cross talk with the androgen receptor (AR) signaling pathway for promotion of carcinogenesis. We have demonstrated that HCV core protein alone or in context with other HCV proteins enhances AR-mediated transcriptional activity and further augments in the presence of androgen. Subsequent study suggested that HCV core protein activates STAT3, which in turn enhances AR-mediated transcription. This activity was blocked by a pharmacological inhibitor of the Jak/Stat signaling pathway, AG490. Vascular endothelial growth factor (VEGF) is a target gene of AR in liver and plays an important role in angiogenesis. Therefore, we examined whether HCV infection modulates VEGF expression in hepatocytes. Our results demonstrated that HCV enhances VEGF expression and facilitates tube formation in human coronary microvascular endothelial cells in the presence of AR. Together, our results suggest that HCV core protein acts as a positive regulator in AR signaling, providing further insight into oncogenic potential in the development of HCC in HCV-infected individuals.
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PMID:Hepatitis C virus core protein augments androgen receptor-mediated signaling. 1876 69

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 ERalpha alone until 1996 when ERbeta 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.
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PMID:Role of sex steroid receptors in pathobiology of hepatocellular carcinoma. 1893 72

Thyroid hormone (T3) regulates growth, development and differentiation. These activities are mediated by nuclear thyroid hormone receptors (TRs), which belong to the steroid/thyroid hormone receptor superfamily of ligand-dependent transcription factors. In an effort to study the mechanism of target genes regulation and their physiological significance after T3 treatment in a TR alpha-overexpressing hepatoma cell line (HepG2-TR alpha), c-DNA microarrays were performed. The data demonstrated that approximately 149 genes represented were positively regulated by T3, including fibrinogen, transferrin, fibronectin (FN), androgen receptor (AR)-associated protein (ARA70), and dehydroepiandrosterone sulfotransferase family 1A member 2 (SULT2A1). To further confirm the microarray results, a quantitative-reverse transcription polymerase chain reaction (Q-RT-PCR) was applied. The protein synthesis inhibitor, cycloheximide was used to determine whether the regulation was direct or indirect. A promoter assay further showed that T3 regulation was largely at the level of transcription. Although those genes were isolated from a human tumor cell line, they are regulated similarly in rats and humans. These results indicate that T3 might play an important role in the process of blood coagulation, inflammation, metabolism and cell proliferation. This may help to explain the association between thyroid diseases and the mis-regulation of the inflammatory and clotting profiles evident in the circulatory systems of these patients.
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PMID:Thyroid hormone dependent regulation of target genes and their physiological significance. 1893 90

Poly(ADP-ribosyl)ation of transcription factors and coregulators, mediated by the poly(ADP-ribose) polymerase PARP-1, has been emerging as an important epigenetic mechanism that controls transcriptional dynamics in response to diverse intra- and extracellular signals. PARP-1 activity is also implicated in the regulation of mammalian lifespan. Herein we show that transcriptional down-regulation of androgen receptor (AR) in the aging rat liver and in oxidatively stressed hepatoma cells involves exchange of a PARP-1-associated, p/CAF-containing coactivator assembly for a p53-interacting, Groucho/TLE1-, and mSin3A-included corepressor complex at an age- and oxidant-responsive DNA element (age-dependent factor (ADF) element) in the AR promoter. The coregulator switch is mediated by B-Myb and c-Myb, which bind to the ADF element and physically associate with PARP-1 and the tumor suppressor p53. Heterogeneous nuclear ribonucleoprotein K, residing at the ADF element in association with PARP-1, may serve a platform role in stabilizing the activating complex. PARP-1 coactivated B-Myb- and c-Myb-mediated transactivation of the AR promoter, and p53 antagonized the B-Myb/c-Myb-induced AR promoter activation. PARP-1, heterogeneous nuclear ribonucleoprotein K, B-Myb, and c-Myb each serves as a positive regulator of cellular AR content, whereas p53 negatively regulates AR expression. Our results identify a shared, PARP-1-regulated sensing mechanism that coordinates transcriptional repression of AR during aging and in response to oxidative stress. This study may provide insights as to how advancing age and intracellular redox balance might influence androgen-regulated physiology.
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PMID:Loss of androgen receptor in aging and oxidative stress through Myb protooncoprotein-regulated reciprocal chromatin dynamics of p53 and poly(ADP-ribose) polymerase PARP-1. 1894 70

Cirrhosis is a premalignant condition leading to hepatocellular carcinoma. Cirrhotic nodules are surrounded by a rim of CK 7/CK19-positive biliary cells termed ductular reaction. Half of all regenerative cirrhotic nodules are thought to be monoclonal by studying the pattern of inactivation of the X-linked human androgen receptor gene (HUMARA). Using a new technique for lineage tracing in human liver based on the identification in the mitochondrial DNA of mutations in the cytochrome c oxidase (CCO) gene, the authors discovered that 20% of regenerative nodules were monoclonal; in addition they showed that hepatic progenitor cells within abutting CCO-deficient cells of the ductular reaction had the same mutations as the adjacent regenerative nodule, indicating a common cell origin. It is the first direct evidence that regenerative nodules in cirrhosis can be derived from hepatic progenitor cells.
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PMID:Human cirrhosis: monoclonal regenerative nodules derived from hepatic progenitor cells abutting ductular reaction. 2043 May 57

Hepatitis B virus (HBV)-induced hepatitis and carcinogen-induced hepatocellular carcinoma (HCC) are associated with serum androgen concentration. However, how androgen or the androgen receptor (AR) contributes to HBV-induced hepatocarcinogenesis remains unclear. We found that hepatic AR promotes HBV-induced hepatocarcinogenesis in HBV transgenic mice that lack AR only in the liver hepatocytes (HBV-L-AR(-/y)). HBV-L-AR(-/y) mice that received a low dose of the carcinogen N'-N'-diethylnitrosamine (DEN) have a lower incidence of HCC and present with smaller tumor sizes, fewer foci formations, and less alpha-fetoprotein HCC marker than do their wild-type HBV-AR(+/y) littermates. We found that hepatic AR increases the HBV viral titer by enhancing HBV RNA transcription through direct binding to the androgen response element near the viral core promoter. This activity forms a positive feedback mechanism with cooperation with its downstream target gene HBx protein to promote hepatocarcinogenesis. Administration of a chemical compound that selectively degrades AR, ASC-J9, was able to suppress HCC tumor size in DEN-HBV-AR(+/y) mice. These results demonstrate that targeting the AR, rather than the androgen, could be developed as a new therapy to battle HBV-induced HCC.
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PMID:Androgen receptor promotes hepatitis B virus-induced hepatocarcinogenesis through modulation of hepatitis B virus RNA transcription. 2048 30

Men have a higher incidence of hepatocellular carcinoma (HCC) than women. Epidemiologic and animal studies have suggested that it might be due to the stimulatory effects of androgen and the protective effects of estrogen. Recently, increasing molecular mechanisms underlying the carcinogenic effect of both sex hormones were reported. Knockout of androgen receptor (AR) expression in hepatocytes delayed the development of N',N'-diethylnitrosamine (DEN)-induced HCC, suggesting the active AR pathway in augmenting the HCC risk. Moreover, an intriguing interaction between the viral protein of hepatitis B virus X protein (HBx) and the androgen pathway was established. HBx can enhance the transcriptional activity of AR in a ligand concentration-dependent manner, mainly through its effects on the c-Src and GSK-3beta kinase pathways. The studies from the DEN-induced HCC mouse model further provided a mechanism for the protective role of estrogen in female HCC. Estrogen can protect hepatocytes from malignant transformation via downregulation of IL-6 release from Kupffer cells, a critical process in this mouse model. Intriguingly, suppression of the ERalpha protein by overexpression of miR-18a, which occurs preferentially in female HCC, was identified as a novel mechanism to block the tumor-protective function of estrogen in female HCC. In conclusion, the current studies demonstrated that the gender disparity of HCC is attributed by both androgen and estrogen sex hormone pathways, with distinct roles in each gender. Therefore, the ligand and the receptor factors of both sex hormones need to be included for assessing the relative risk of HCC patients of each gender.
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PMID:Gender disparity of hepatocellular carcinoma: the roles of sex hormones. 2061 1


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