Early Stages Of Hepatocarcinogenesis Research Articles

Abstract PR02: PMEPA1 has an oncogenic role in the context of TGF-β signaling in hepatocellular carcinoma

Abstract Background: Transforming growth factor β (TGFβ) has a dual role in cancer, including hepatocellular carcinoma (HCC). It acts as a tumor suppressor in early stages of hepatocarcinogenesis, but promotes epithelial-to-mesenchymal transition, angiogenesis and immunosuppression in advanced stages. PMEPA1 (prostate transmembrane protein androgen induced 1) negatively regulates TGFβ signaling by interacting with SMAD proteins, and has been shown to promote TGFβ oncogenic effects in other cancers. Thus, we aimed to explore the role of PMEPA1 in HCC pathogenesis. Methods: We analyzed transcriptomic, genomic, epigenomic and clinicopathological data of a discovery cohort comprising 228 HCCs and a validation cohort of 361 HCCs. PMEPA1 levels were quantified by qPCR in the discovery cohort. PMEPA1 overexpression was validated in 6 independent publicly available cohorts (n = 916) with either microarray or RNAseq data. We also evaluated PMEPA1 expression at the single-cell level using a publicly available single-cell RNA sequencing (scRNAseq) dataset comprising 22 HCC samples. Genetically engineered mouse models were generated by performing hydrodynamic tail-vein injection of equal amounts of plasmids overexpressing MYC and MYC+PMEPA1. Molecular and histopathological analyses of the murine tumors are currently ongoing. Results: PMEPA1 was overexpressed in 18% of human HCCs [FC > 2; n = 203/1144], a feature associated with TGFβ signaling (p < 0.05). Overexpression of PMEPA1 was associated with gene body hypermethylation (p < 0.0001). HCCs displaying both TGFβ signaling and high PMEPA1 levels (11% of cases) were significantly enriched in signatures of immune exhaustion, late TGFβ activation, tumor microenvironment (TME) response to TGFβ and active stroma (p < 0.05) when compared with HCCs with TGFβ signalling alone (8% of cases) or PMEPA1 overexpression alone (11% of cases). Analyses of PMEPA1 expression at the single-cell level revealed that this gene is not only expressed by tumoral cells but also by the TME cell populations, including endothelial cells, pericytes, fibroblasts, and dendritic cells. In vivo, overexpression of MYC+PMEPA1 led to HCC development in 9/16 mice and was associated with a significantly reduced survival when compared to mice overexpressing MYC alone (p = 0.014), which did not develop tumors. Compared to healthy liver controls, MYC+PMEPA1 tumors presented upregulation of AKT. Conclusion: PMEPA1 upregulation is linked to TGF-β activation and an aggressive phenotype in human HCC. Overexpression of PMEPA1 in combination with MYC in vivo led to HCC development, showing for the first time the oncogenic role of PMEPA1 in this cancer type. Citation Format: Marta Piqué-Gili, Carmen Andreu-Oller, Roser Pinyol, Roger Esteban, Marina Bárcena-Varela, Judit Peix, Jordi Abril-Fornaguera, Katherine E. Lindblad, Miguel Torres-Martin, Júlia Huguet-Pradell, Daniela Sia, Amaia Lujambio, Josep M Llovet. PMEPA1 has an oncogenic role in the context of TGF-β signaling in hepatocellular carcinoma [abstract]. In: Proceedings of the AACR Special Conference: Advances in the Pathogenesis and Molecular Therapies of Liver Cancer; 2022 May 5-8; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(17_Suppl):Abstract nr PR02.

Abstract 840: PMEPA1 is an oncogene linked to TGF-β signaling in hepatocellular carcinoma

Abstract Background: Transforming growth factor β (TGFβ) has a dual role in cancer, including hepatocellular carcinoma (HCC). It acts as a tumor suppressor in early stages of hepatocarcinogenesis, but promotes epithelial-to-mesenchymal transition, angiogenesis and immunosuppression in advanced stages. PMEPA1 (prostate transmembrane protein androgen induced 1), a direct target gene of the TGFβ pathway that negatively regulates TGFβ signaling by interacting with SMAD proteins, has been shown to promote TGFβ oncogenic effects in other cancers and we decided to explore its role in HCC pathogenesis. Methods: We analyzed transcriptomic, genomic, epigenomic and clinicopathological data of a discovery cohort of 228 HCCs and a validation cohort of 361 HCCs. PMEPA1 levels were quantified by qPCR in the discovery cohort. PMEPA1 overexpression was validated in 6 independent cohorts (n = 916) using microarray and RNAseq data. Genetically engineered mouse models were generated through hydrodynamic tail-vein injection. Equal amounts of plasmids overexpressing PMEPA1, TGFB1 and MYC were injected in mice to evaluate survival. Molecular and histopathological analyses of the murine tumors are currently ongoing. Results: PMEPA1 was overexpressed in 18% of human HCCs [FC > 2; n = 203/1144], a feature associated with TGFβ signaling (p < 0.05). Overexpression of PMEPA1 was associated with gene body hypermethylation (p < 0.0001). HCCs displaying both TGFβ signaling and high PMEPA1 levels (11% of cases) were significantly enriched in signatures of immune exhaustion, late TGFβ activation, TME response to TGFβ and active stroma (p < 0.05) compared to HCCs with TGFβ signalling alone (8% of cases) or PMEPA1 high levels alone (11% of cases). In vivo, overexpression of MYC+PMEPA1 led to HCC development in 9/16 mice and showed a lower survival when compared to the control arm, overexpression of MYC alone (p = 0.014). On the contrary, only 1/12 mice in the MYC+PMEPA1+TGFβ1 condition developed HCC and none of the MYC+TGFβ1 mice. Conclusion: PMEPA1 upregulation is linked to TGF-β activation and an aggressive phenotype in human HCC. Overexpression PMEPA1 in combination with MYC in vivo led to HCC development, showing for the first time the oncogenic role of PMEPA1 in this cancer. Citation Format: Marta Piqué-Gili, Carmen Andreu-Oller, Roser Pinyol, Marina Bárcena-Varela, Roger Esteban-Fabró, Judit Peix, Jordi Abril-Fornaguera, Katherine E. Lindblad, Miguel Torres-Martin, Daniela Sia, Amaia Lujambio, Josep M. Llovet. PMEPA1 is an oncogene linked to TGF-β signaling in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 840.

The Mutational and Transcriptional Landscapes of Hepatocarcinogenesis in a Rat Model.

SummaryHepatocellular carcinoma (HCC) initiation is characterized by stepwise accumulation of molecular alterations, during which the early events are largely unknown. Here, we presented a comprehensive genomic and transcriptomic landscape at stages of hepatitis, cirrhosis, and HCC by using a diethylnitrosamine-induced rat HCC model. We observed the early occurrence of gene instability and aberrant cancer associated signaling pathways in liver hepatitis. We further characterized the progressive molecular changes during hepatocarcinogenesis, wherein the intense rivalry between tumor-suppressive and oncogenic strengths occurred in cirrhosis stage. Despite the significant pathological difference, mutation signatures and expression landscape are highly similar between hepatitis and cirrhosis stages. Furthermore, we identified PI3K-Akt signaling pathway as a key pathway in the process of hepatocarcinogenesis through integrative analysis, and PIK3CD is a potential biomarker indicating HCC recurrence. The dynamic immune response during hepatocarcinogenesis, such as continuous decline of monocytes, suggests an immunological intervention strategy beyond chemoprevention for liver cancer.

Protective Effects of Dietary Capsaicin on the Initiation Step of a Two-Stage Hepatocarcinogenesis Rat Model

Capsaicin (CPS), an ingredient of Capsicum plants, has anti-inflammatory, antioxidant and antitumoral properties. The mechanisms of CPS on hepatocarcinogenesis preclinical bioassays are not described. Thus, the protective effects CPS were evaluated in the early stages of chemically-induced hepatocarcinogenesis. Male Wistar rats received diet containing 0.01% or 0.02% CPS for 3 weeks. Afterwards, animals received a dose of hepatocarcinogen diethylnitrosamine (DEN, 100 mg/kg body weight). From weeks 4–12, groups had their diet replaced by a 0.05% phenobarbital supplemented one to promote DEN-induced preneoplastic lesions. Animals were euthanized 24 h after DEN administration (n = 5/group) or at week 12 (n = 9/group). The estimated CPS intake in rats resembled human consumption. At the end of week 3, dietary 0.02% CPS attenuated DEN-induced oxidative damage and, consequently, hepatocyte necrosis by reducing serum alanine aminotransferase levels, liver CD68-positive macrophages, lipid peroxidation, while increasing antioxidant glutathione system. Additionally, 0.02% CPS upregulated vanilloid Trpv1 receptor and anti-inflammatory epoxygenase Cyp2j4 genes in the liver. Ultimately, previous 0.02% CPS intake decreased the number of GST-P-positive preneoplastic lesions at week 12. Thus, CPS attenuated preneoplastic lesion development, primarily by diminishing DEN-induced oxidative liver injury. Findings indicate that CPS is a promising chemopreventive agent when administered after and during the early stages of hepatocarcinogenesis.

Gadoxetic acid-enhanced MR imaging for hepatocellular carcinoma: molecular and genetic background.

Gadoxetic acid-enhanced magnetic resonance imaging (MRI) plays important roles in diagnosis of hepatic lesions because of its superiority in the detectability of small lesions, its differentiation ability, and its utility for the early diagnosis of hepatocellular carcinoma (HCC). In HCC, expression of organic anion transporting polypeptide (OATP) 1B3 correlates with the enhancement ratio in the hepatobiliary phase. Gadoxetic acid-enhanced MRI, an indirect molecular imaging method, reflects OATP1B3 expression in HCC. OATP1B3 expression gradually decreases from the dysplastic nodule stage to advanced HCC. Decreased expression is a sensitive marker of multistep hepatocarcinogenesis, especially in the early stages. Hypervascular HCCs commonly show hypointensity in the hepatobiliary phase corresponding to a decrease in OATP1B3; however, approximately 10% of HCCs show hyperintensity due to OATP1B3 overexpression. This hyperintense HCC shows less aggressive biological features and has a better prognosis than hypointense HCC. Hyperintense HCC can be classified into a genetic subtype of HCC with a mature hepatocyte-like molecular expression. OATP1B3 expression and the less aggressive nature of hyperintense HCC are regulated by the molecular interaction of β-catenin signaling and hepatocyte nuclear factor 4α, a tumor suppressor factor. Gadoxetic acid-enhanced MR imaging has the potential to be an imaging biomarker for HCC. KEY POINTS: • The hepatobiliary phase is a sensitive indirect indicator of organic anion transporting polypeptide1B3 (OATP1B3) expression in hepatocellular carcinoma (HCC). • The OATP1B3 expression, namely, enhancement in the hepatobiliary phase, decreases from the very early stage of hepatocarcinogenesis, contributing to early diagnosis of HCC. • HCC showing hyperintensity on the hepatobiliary phase is a peculiar genetic subtype of HCC with OATP1B3 overexpression, a less aggressive nature, and mature hepatocyte-like molecular/genetic features.

A Discovery of Clinically Approved Formula FBRP for Repositioning to Treat HCC by Inhibiting PI3K/AKT/NF-κB Activation

Drug repositioning offers new clinical applications for existing drugs with shorter approval processes and lower costs and risks than de novo experimental drug development. The Fufang-Biejia-Ruangan pill (FBRP) is the first clinically approved anti-fibrosis herbal formula in China. Whether FBRP could be used to treat hepatocellular carcinoma (HCC) remains unclear. Herein, a total of 161 FBRP candidate targets against HCC were identified according to the topological importance in the “hepatic fibrosis-cirrhosis-cancer axis-related gene-FBRP putative target” network, and mostly enriched in phosphatidylinositol 3-kinase (PI3K)/AKT/nuclear factor κB (NF-κB) signaling. Experimentally, FBRP inhibited liver fibrosis and prevented the development of neoplastic lesions at the early stages of hepatocarcinogenesis in a diethylnitrosamine-induced rat HCC model. FBRP inhibited tumor cell proliferation, induced tumor-specific cell death, and suppressed tumor progression in HCC rats while preventing the activation of PI3K, AKT and IKΚB proteins, reducing the nuclear accumulation of NFΚB1 protein, and decreasing the downstream expression of proteins. Consistently, FBRP suppressed HCC cell proliferation and induced cell cycle arrest in vitro. Co-treatment of FBRP with PI3K inhibitor exhibited an additive inhibitory effect on PI3K/AKT/NF-κB activation. Collectively, our data showed the potentials of FBRP in hepatic fibrosis microenvironment regulation and tumor prevention, suggesting that FBRP may be a promising candidate drug for reduction of fibrogenesis and prevention of HCC.

Protective Effects of Defatted Sticky Rice Bran Extracts on the Early Stages of Hepatocarcinogenesis in Rats.

Use of natural products is one strategy to lessen cancer incidence. Rice bran, especially from colored rice, contains high antioxidant activity. Cancer chemopreventive effects of hydrophilic purple rice bran extract (PRBE) and white rice bran extract (WRBE) on carcinogen-induced preneoplastic lesion formation in livers of rats were investigated. A 15-week administration of PRBE and WRBE did not induce hepatic glutathione S-transferase placental form (GST-P) positive foci formation as the biomarker of rat hepatocarcinogenesis. PRBE and WRBE at 500 mg/kg body weight significantly decreased number and size of GST-P positive foci in diethylnitrosamine (DEN)-initiated rats. The number of proliferating nuclear antigen positive hepatocytes were also reduced in preneoplastic lesions in both PRBE and WRBE fed DEN-treated rats. Notably, the inhibitory effect on GST-P positive foci formation induced by DEN during the initiation stage was found only in rats treated by PRBE for five weeks. Furthermore, PRBE attenuated the expression of proinflammatory cytokines involving genes including TNF-α, iNOS, and NF-κB. PBRE contained a higher number of anthocyanins and other phenolic compounds and vitamin E. PRBE might protect DEN-induced hepatocarcinogenesis in rats via attenuation of cellular inflammation and cell proliferation. Anthocyanins and other phenolic compounds, as well as vitamin E, might play a role in cancer chemopreventive activity in rice bran extract.

Potential effect of Nigella sativa against Diethylnitrosamine-induced hepatocarcinogenesis in rats

Objective of the investigation was the study of potential protective effects of the watery extract of Nigella sativa against diethylnitrosamine induced hepatocarcinogenesis in rats. N. sativa was administered to rats for protection against diethylnitrosamine-induced hepatocarcinogenesis. It was administered prior to, simultaneously with or after injection of diethylnitrosamine. Five groups of Wister rats were used. Group A was administered diethylnitrosamine and N. sativa simultaneously, group B was administered only diethylnitrosamine and group C received only N. sativa. These three groups were maintained for up to eight weeks. Group D received N. sativa six weeks after administration ofdiethylnitrosamine,while group E (“protective group”) received N. sativa on day 1 and diethylnitrosamine six weeks later. These two groups were maintained for up to 12 weeks. All rats were subjected to partial hepatectomy to enhance carcinogenesis. P-isoform of glutathione s transferase (GST-P) was detected in the cytoplasm and nuclei of hepatocytes. The number of GST-P positive foci was significantly smaller in test groups (A, D, E), particularly in groups A and E, when compared with to those in group B, indicating that N. sativa has protective effects against diethylnitrosamine induced liver cancer in rats, even in the very early stages of hepatocarcinogenesis.

Abstract 5245: Peretinoin prevents the accumulation of somatic gene mutations and reverts neoplastic lesions to normal liver-like in platelet-derived growth factor-c transgenic mice

Abstract Hepatocellular carcinoma (HCC) develops with progressive accumulation of multiple genetic changes. An acyclic retinoid peretinoin is reported to suppress the development of HCC, but the molecular mechanism in detail remains to be obscure. Here we evaluated the effect of peretinoin on preneoplastic nodules and HCC developed in platelet derived growth factor-c (PDGF-C) transgenic mice liver by gadolinium ethoxybenzyl diethylenetriamide pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and whole exome sequence analysis. We confirmed the progressive accumulation of somatic mutations in hypervascular liver cancer tissues compared with hypovascular precancerous tissues and non-cancerous background liver tissues in PDGF-C transgenic mice. Surprisingly, peretinoin treatment in HCC as well as preneoplastic nodules resulted in the accumulation of less gene mutations compared with vehicle. Gd-EOB-DTPA uptake capacity and its transporter OATP1 was confirmed to be re-activated in peretinoin treated nodules in mice. Gene and protein expression analysis indicated the inactivation of cell cycle with low Ki-67 labeling indexes in peretinoin treated nodules. The reversion of Gd-EOB-DTPA uptake capacity was confirmed in preneoplastic nodules and a subset of classical hypervascular HCCs. Notably, peretinoin supplementation induced the expression of OATP1B3 in mature hepatocyte-like HCC cell lines in vitro, whereas supplementation of tretinoin (all-trans retinoic acid) had no such effects and rather suppressed OATP1B3. Taken together, our data suggested the utility of peretinoin to revert the malignant transformation processes of hepatocytes by preventing accumulation of gene mutations especially in early stages of hepatocarcinogenesis. Peretinoin but not tretinoin can induce the expression of a mature hepatocyte marker OATP1B3, suggesting that peretinoin may exert its anti-tumor effect with hepatocytic differentiation capacity independently of the activation of retinoic acid signaling. Note: This abstract was not presented at the meeting. Citation Format: Taro Yamashita, Hikari Okada, Masao Honda, Shuichi Kaneko. Peretinoin prevents the accumulation of somatic gene mutations and reverts neoplastic lesions to normal liver-like in platelet-derived growth factor-c transgenic mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5245. doi:10.1158/1538-7445.AM2017-5245

Nonalcoholic steatohepatitis-related hepatocellular carcinoma: is there a role for the androgen receptor pathway?

The epidemic of insulin resistance, obesity, and metabolic syndrome has led to the emergence of nonalcoholic steatohepatitis (NASH) as the most common cause of liver disease in the US. Patients with NASH are at an increased risk for hepatic disease-related morbidity and death, and chronic inflammation in NASH patients can lead to hepatocellular carcinoma (HCC). The prevalence of HCC is higher in males than in females, and genetic studies have identified androgen and androgen receptors (ARs) as partially responsible for the gender disparity in the development of liver disease and HCC. Although many factors are known to play important roles in the progression of inflammation in NASH patients, the role of androgen and AR in the progression of NASH to HCC has been understudied. This review summarizes the evidence for a potential role of androgen and the AR pathway in the development of NASH-related HCC and in the treatment of HCC. It has been proposed that AR plays a role in the progression of HCC: inhibitory roles in early stages of hepatocarcinogenesis and tumor-promoting roles in advanced stages. AR can be activated by several pathways, even in the absence of androgen. While AR has been explored as a potential therapeutic target in HCC, several clinical trials have failed to demonstrate a clinical benefit of antiandrogen drugs in HCC. This review discusses the potential reason for these observations and discuss the potential future trials design in this important setting.

Apocynin and enzymatically modified isoquercitrin suppress the expression of a NADPH oxidase subunit p22phox in steatosis-related preneoplastic liver foci of rats

We determined effects of the NADPH oxidase (NOX) inhibitor apocynin (APO) or the antioxidant enzymatically modified isoquercitrin (EMIQ) on an early stage of hepatocarcinogenesis in the liver with steatosis. Male rats were given a single intraperitoneal injection of N-diethylnitrosamine (DEN) and fed a high-fat diet (HFD) to subject to a two-stage hepatocarcinogenesis model. Two weeks later, rats were fed a HFD containing the lipogenic substance malachite green (MG), which were co-administered with EMIQ or APO in drinking water for 6 weeks. Three after DEN initiation, rats were subjected to a two-third partial hepatectomy to enhance cell proliferation. The HFD increased total cholesterol and alkaline phosphatase levels, which were reduced by EMIQ co-administration. APO co-administration reduced MG-increased preneoplastic liver lesions, glutathione S-transferase placental form (GST-P)-positive, adipophilin-negative liver foci, and tended to decrease MG-increased Ki-67-positive or active caspase-3-positive cells in the liver foci. EMIQ or APO co-administration reduced the expression of a NOX subunit p22phox in the liver foci, but did not alter the numbers of LC3a-positive cells, an autophagy marker. We identified no treatment-related effects on p47phox and NOX4 expression in the liver foci. The results indicated that APO or EMIQ had the potential to suppress hyperlipidaemia and steatosis-preneoplastic liver lesions, through suppression of NOX subunit expression in rats.

Abstract 1009: Metabolic reprogramming discriminates aggressive vs. slowly growing preneoplastic lesions at early stages of HCC development

Abstract Introduction and aim: Among the several changes underlying metabolic reprogramming of cancer cells, increased glucose utilization and its uncoupling from oxygen availability is a well-established phenomenon and has been recognized as a hallmark of cancer. To what extent these metabolic changes are important for the progression of slow growing tumors and whether a metabolic rewiring occurs in the very early stages of neoplastic progression represent key questions on the significance of these metabolic alterations in cancer. Here, we compared the metabolic features of preneoplastic hepatic lesions with those of advanced hepatocellular carcinomas (HCCs) and of proliferating liver, following partial hepatectomy (PH). Materials and Methods: Expression levels, activity and modulation of several enzymes with key roles in glycolysis, pentose phosphate pathway (PPP) and oxidative phosphorylation (OXPHOS) were assessed in preneoplastic hepatic lesions and HCC, induced in rats exposed to the Resistant-Hepatocyte (R-H) model. In vitro experiments were performed on HCC cells obtained by perfusion of HCC-bearing rats. Expression of metabolic genes was also investigated in two different cohorts of human patients carrying HCC. Results and discussion: A switch from OXPHOS to PPP was observed in very early preneoplastic lesions generated 10 weeks after the treatment with DENA. Notably, this metabolic reprogramming was observed only in the most aggressive preneoplastic lesions, characterized by positivity for cytokeratin 19 (CK-19+). PPP induction, shown by a strong increase in the expression and activity of glucose 6-phosphate dehydrogenase (G6PD) was supported both by inhibition of pyruvate kinase activity and by TP53-inducible glycolysis and apoptosis regulator (TIGAR) induction. Importantly, such metabolic rewiring was not observed in normal hepatocytes, undergoing proliferation following 2/3 partial hepatectomy (PH). Activation of the NRF2/KEAP1 pathway and down-regulation of miR-1 accompanied the metabolic reprogramming in CK-19+ preneoplastic lesions. Accordingly, NRF2 silencing decreased G6PD and increased miR-1 expression, consequently inhibiting PPP, while forced expression of miR-1 downregulated G6PD expression in HCC cells. Finally, an inverse correlation between miR-1 and its target gene G6PD was found in human HCC patients. Conclusion: These results demonstrate that metabolic reprogramming takes place at early stages of hepatocarcinogenesis and is likely the consequence of the concomitant activation of the NRF2-KEAP1 pathway. Citation Format: Marta A. Kowalik, Giulia Guzzo, Andrea Morandi, Andrea Perra, Silvia Menegon, Ionica Masgras, Elena Trevisan, Maria M. Angioni, Francesca Fornari, Luca Quagliata, Giovanna M. Ledda-Columbano, Laura Gramantieri, Luigi Terracciano, Silvia Giordano, Paola Chiarugi, Andrea Rasola, Amedeo Columbano. Metabolic reprogramming discriminates aggressive vs. slowly growing preneoplastic lesions at early stages of HCC development. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1009.

Gene silencing of Nox4 by CpG island methylation during hepatocarcinogenesis in rats.

ABSTRACTThe association between the downregulation of genes and DNA methylation in their CpG islands has been extensively studied as a mechanism that favors carcinogenesis. The objective of this study was to analyze the methylation of a set of genes selected based on their microarray expression profiles during the process of hepatocarcinogenesis. Rats were euthanized at: 24 h, 7, 11, 16 and 30 days and 5, 9, 12 and 18 months post-treatment. We evaluated the methylation status in the CpG islands of four deregulated genes (Casp3, Cldn1, Pex11a and Nox4) using methylation-sensitive high-resolution melting technology for the samples obtained from different stages of hepatocarcinogenesis. We did not observe methylation in Casp3, Cldn1 or Pex11a. However, Nox4 exhibited altered methylation patterns, reaching a maximum of 10%, even during the early stages of hepatocarcinogenesis. We observed downregulation of mRNA and protein of Nox4 (97.5% and 40%, respectively) after the first carcinogenic stimulus relative to the untreated samples. Our results suggest that Nox4 downregulation is associated with DNA methylation of the CpG island in its promoter. We propose that methylation is a mechanism that can silence the expression of Nox4, which could contribute to the acquisition of neoplastic characteristics during hepatocarcinogenesis in rats.

Anti-cancer and anti-hepatitis C virus NS5B polymerase activity of etodolac 1,2,4-triazoles

Arachidonic acid is an unsaturated fatty acid liberated from phospholipids of cell membranes. NSAIDs are known as targets of cyclooxygenase enzyme (COX-1, COX-2 and COX-3) in arachidonic acid metabolism. This mechanism of COX-2 in carcinogenesis causes cancer. In addition, COX-2 plays a role in the early stages of hepatocarcinogenesis. Hepatitis C virus (HCV) infection is cause of liver cirrhosis and hepatocellular carcinoma (HCC). The aim of our study was to improve effective agents against HCV. A novel series of new etodolac 1,2,4-triazoles derivatives (4a–h) have been synthesized and investigated for their activity against HCV NS5B polymerase. Compound 4a was found to be the most active with IC50 value of 14.8 µM. In accordance with these results, compound 4a was screened for anti-cancer activity on liver cancer cell lines (Huh7, Mahlavu, HepG2, FOCUS). Compound 4a showed anti-cancer activity against Huh7 human hepatoma cell line with IC50 value of 4.29 µM. Therefore, compound 4a could be considered as a new anti-cancer and anti-HCV lead compound.

Comprehensive analysis of DNA methylation and gene expression of rat liver in a 2-stage hepatocarcinogenesis model

Recent studies have shown that epigenetic alterations correlate with carcinogenesis in various tissues. Identification of these alterations might help characterize the early stages of carcinogenesis. We comprehensively analyzed DNA methylation and gene expression in livers obtained from rats exposed to nitrosodiethylamine (DEN) followed by a promoter of hepatic carcinogenesis, phenobarbital (PB). The combination of DEN and PB induced marked increases in number and area of glutathione S-transferase-placental form (GST-P)-positive foci in the liver. In the liver of rats that received 30 mg/kg of DEN, pathway analysis revealed alterations of common genes in terms of gene expression and DNA methylation, and that these alterations were related to immune responses. Hierarchical clustering analysis of the expression of common genes from public data obtained through the Toxicogenomics Project-Genomics Assisted Toxicity Evaluation system (TG-GATEs) showed that carcinogenic compounds clustered together. MBD-seq and GeneChip analysis indicated that major histocompatibility complex class Ib gene RT1-CE5, which has an important role in antigen presentation, was hypomethylated around the promoter region and specifically induced in the livers of DEN-treated rats. Further, immunohistochemical analysis indicated that the co-localization of GST-P and protein homologous to RT1-CE5 was present at the foci of some regions. These results suggest that common genes were altered in terms of both DNA methylation and expression in livers, with preneoplastic foci indicating carcinogenic potential, and that immune responses are involved in early carcinogenesis. In conclusion, the present study identified a specific profile of DNA methylation and gene expression in livers with preneoplastic foci. Early epigenetic perturbations of immune responses might correlate with the early stages of hepatocarcinogenesis.

MicroRNA/gene profiling unveils early molecular changes and nuclear factor erythroid related factor 2 (NRF2) activation in a rat model recapitulating human hepatocellular carcinoma (HCC)

Studies on gene and/or microRNA (miRNA) dysregulation in the early stages of hepatocarcinogenesis are hampered by the difficulty of diagnosing early lesions in humans. Experimental models recapitulating human hepatocellular carcinoma (HCC) are then used to perform this analysis. We performed miRNA and gene expression profiling to characterize the molecular events involved in the multistep process of hepatocarcinogenesis in the resistant-hepatocyte rat model. A high percentage of dysregulated miRNAs/genes in HCC were similarly altered in early preneoplastic lesions positive for the stem/progenitor cell marker cytokeratin-19, indicating that several HCC-associated alterations occur from the very beginning of the carcinogenic process. Our analysis also identified miRNA/gene-target networks aberrantly activated at the initial stage of hepatocarcinogenesis. Activation of the nuclear factor erythroid related factor 2 (NRF2) pathway and up-regulation of the miR-200 family were among the most prominent changes. The relevance of these alterations in the development of HCC was confirmed by the observation that NRF2 silencing impaired while miR-200a overexpression promoted HCC cell proliferation in vitro. Moreover, T3-induced in vivo inhibition of the NRF2 pathway accompanied the regression of cytokeratin-19-positive nodules, suggesting that activation of this transcription factor contributes to the onset and progression of preneoplastic lesions towards malignancy. The finding that 78% of genes and 57% of dysregulated miRNAs in rat HCC have been previously associated with human HCC as well underlines the translational value of our results. This study indicates that most of the molecular changes found in HCC occur in the very early stages of hepatocarcinogenesis. Among these, the NRF2 pathway plays a relevant role and may represent a new therapeutic target.

Reactive Oxygen Species Induce Epigenetic Instability through the Formation of 8-Hydroxydeoxyguanosine in Human Hepatocarcinogenesis

Chronic hepatitis C (CHC) triggers oxidative stress and contributes to the emergence of hepatocellular carcinoma (HCC). We previously reported that tumor suppressor gene (TSG) methylation is a critical factor during the early stages of hepatocarcinogenesis. In this study, we clarify the association between oxidative stress and epigenetic alterations during hepatocarcinogenesis. We examined DNA oxidation and methylation profiles in 128 liver biopsy samples from CHC patients. The DNA oxidation and methylated TSG numbers were quantified using immunohistochemical analysis of 8-hydroxydeoxyguanosine (8-OHdG) and quantitative PCR for 11 TSGs, respectively. The quantitative chromatin immunoprecipitation-PCR (ChIP-qPCR) assay in HepG2 and fetal liver Hc cells treated with H₂O₂ was used to quantify trimethyl-H3K4, acetylated-H4K16 (an active chromatin marker), trimethyl-H3K27 (a repressive chromatin marker) and 8-OHdG. We analyzed 30 promoters of 25 different TSGs by qPCR. The high levels of 8-OHdG was the only variable that was significantly associated with the increased number of methylated TSGs in CHC (p < 0.0001). The ChIP-qPCR revealed that after H₂O₂ treatment of the cell lines, the 8-OHdG-bound promoters showed a modification from an active chromatin (trimethyl-H3K4 and acetylated-H4K16 dominant) to a repressive chromatin (trimethyl-H3K27 dominant) status. We conclude that oxidative stress alters the chromatin status, which leads to abnormal methylation of TSGs, and contributes to hepatocarcinogenesis in CHC patients.

Liver-Specific Expressions of HBx and src in the p53 Mutant Trigger Hepatocarcinogenesis in Zebrafish

Hepatocarcinogenesis is a multistep process that starts from fatty liver and transitions to fibrosis and, finally, into cancer. Many etiological factors, including hepatitis B virus X antigen (HBx) and p53 mutations, have been implicated in hepatocarcinogenesis. However, potential synergistic effects between these two factors and the underlying mechanisms by which they promote hepatocarcinogenesis are still unclear. In this report, we show that the synergistic action of HBx and p53 mutation triggers progressive hepatocellular carcinoma (HCC) formation via src activation in zebrafish. Liver-specific expression of HBx in wild-type zebrafish caused steatosis, fibrosis and glycogen accumulation. However, the induction of tumorigenesis by HBx was only observed in p53 mutant fish and occurred in association with the up-regulation and activation of the src tyrosine kinase pathway. Furthermore, the overexpression of src in p53 mutant zebrafish also caused hyperplasia, HCC, and sarcomatoid HCC, which were accompanied by increased levels of the signaling proteins p-erk, p-akt, myc, jnk1 and vegf. Increased expression levels of lipogenic factors and the genes involved in lipid metabolism and glycogen storage were detected during the early stages of hepatocarcinogenesis in the HBx and src transgenic zebrafish. The up-regulation of genes involved in cell cycle regulation, tumor progression and other molecular hallmarks of human liver cancer were found at later stages in both HBx and src transgenic, p53 mutant zebrafish. Together, our study demonstrates that HBx and src overexpression induced hepatocarcinogenesis in p53 mutant zebrafish. This phenomenon mimics human HCC formation and provides potential in vivo platforms for drug screening for therapies for human liver cancer.

Elevated expression of coactivator-associated arginine methyltransferase 1 is associated with early hepatocarcinogenesis

Aberrant expression of regulators for epigenetics is involved in tumorigenesis. There is an urgent need to identify and characterize regulators concerned with epigenetics in the early stages of hepatocarcinogenesis. In the present study, we found that the expression of coactivator-associated arginine methyltransferase 1 (CARM1), a histone methyltransferase that functions as a cofactor for nuclear hormone receptors and several transcription factors, was elevated in adenomas and aberrant in carcinomas during hepatocellular carcinogenesis. In addition to RNA expression, immunohistochemical staining of liver sections revealed that CARM1 was highly expressed in the nucleus of tumor marker glutathione S-transferase placental form (GST-P)-positive foci. Neoplastic transformation of GST-P-positive foci guides the formation of hepatocellular carcinomas. CARM1 expression was not elevated in GST-P-negative regions. Furthermore, a luciferase reporter analysis revealed that CARM1 activated the Gst-p promoter in H4IIE, a hepatocellular carcinoma cell line. This activation was mediated by the enhancer element responsible for the carcinogenic-specific expression of Gst-p and nuclear factor E2-related factor2. Knockdown of Carm1 by shRNA in H4IIE cells inhibited cell proliferation. These findings suggest that aberrantly expressed CARM1 in tumor marker-positive cells promotes tumorigenesis in the early stages of hepatocarcinogenesis.

Expression patterns of cell cycle proteins in the livers of rats treated with hepatocarcinogens for 28 days

Some hepatocarcinogens induce cytomegaly, which reflects aberrant cell cycling and increased ploidy, from the early stages of administration to animals. To clarify the regulatory molecular mechanisms behind cell cycle aberrations related to the early stages of hepatocarcinogenesis, we performed gene expression analysis using microarrays and real-time reverse transcription polymerase chain reaction followed by immunohistochemical analysis in the livers of rats treated with the cytomegaly inducing hepatocarcinogens thioacetamide (TAA), fenbendazole, and methyleugenol, the cytomegaly non-inducing hepatocarcinogen piperonyl butoxide (PBO), or the non-carcinogenic hepatotoxicants acetaminophen and α-naphthyl isothiocyanate, for 28 days. Gene expression profiling showed that cell cycle-related genes, especially those of G(2)/M phase, were mostly upregulated after TAA treatment. Immunohistochemical analysis was performed on cell cycle proteins that were upregulated by TAA treatment and on related proteins. All hepatocarcinogens, irrespective of their cytomegaly inducing potential, increased liver cells immunoreactive for p21(Cip1), which acts on cells arrested in G(1) phase, and for Aurora B or Incenp, which is suggestive of an increase in a cell population with chromosomal instability caused by overexpression. PBO did not induce cell proliferation after 28-day treatment. Hepatocarcinogens that induced cell proliferation after 28-day treatment also caused an increase in p53(+) cells in parallel with increased apoptotic cells, as well as increased population of cells expressing M phase-related proteins nuclear Cdc2, phospho-Histone H3, and HP1α. These results suggest that hepatocarcinogens may increase cellular populations arrested in G1 phase or showing chromosomal instability after 28-day treatment. Hepatocarcinogens that induce cell cycle facilitation may cause M phase arrest accompanied by apoptosis.