Alterations of RB1, p53 and Wnt pathways in hepatocellular carcinomas associated with hepatitis C, hepatitis B and alcoholic liver cirrhosis

Nuclear to cytoplasmic transport is a druggable dependency in MYC-driven hepatocellular carcinoma

The MYC oncogene is often dysregulated in human cancer, including hepatocellular carcinoma (HCC). MYC is considered undruggable to date. Here, we comprehensively identify genes essential for survival of MYChigh but not MYClow cells by a CRISPR/Cas9 genome-wide screen in a MYC-conditional HCC model. Our screen uncovers novel MYC synthetic lethal (MYC-SL) interactions and identifies most MYC-SL genes described previously. In particular, the screen reveals nucleocytoplasmic transport to be a MYC-SL interaction. We show that the majority of MYC-SL nucleocytoplasmic transport genes are upregulated in MYChigh murine HCC and are associated with poor survival in HCC patients. Inhibiting Exportin-1 (XPO1) in vivo induces marked tumor regression in an autochthonous MYC-transgenic HCC model and inhibits tumor growth in HCC patient-derived xenografts. XPO1 expression is associated with poor prognosis only in HCC patients with high MYC activity. We infer that MYC may generally regulate and require altered expression of nucleocytoplasmic transport genes for tumorigenesis.

Molecular insights on intracellular Wnt/β-catenin signaling in alcoholic liver disease

Alcoholic liver disease (ALD) is one of the most common health problems worldwide, especially in developing countries caused by chronic consumption of alcohol on a daily basis. The ALD spectrum is initiated with the early stages of alcoholic fatty liver (steatosis), progressing to alcoholic steatohepatitis, followed by the later stages of fibrosis and in some cases, cirrhosis and hepatocellular carcinoma (HCC). The Wnt/β-catenin signaling required for healthy liver development, function, and regeneration is found to be aberrated in ALD, attributed to its progression. This review is to elucidate the association of Wnt/β-catenin signaling with various stages of ALD progression. Alcohol causes downregulation of Wnt/β-catenin signaling components and thereby suppressing the pathway. Reports have been published that aberrated Wnt/β-catenin signaling, especially the absence of β-catenin, results in decreased alcohol metabolism, causing steatosis followed by steatohepatitis via lipid accumulation, lipid peroxidation, liver injury, increased oxidative stress and apoptosis of hepatocytes, contributing to the advancement of ALD. Contrastingly, the progression of later stages of ALD like fibrosis and HCC depends on the increased activation of Wnt/β-catenin signaling and its components. Existing studies reveal the varied expression of Wnt/β-catenin signaling in ALD. However, the dual role of the Wnt/β-catenin pathway in earlier and later stages of ALD is not clear. Therefore, studies on the Wnt/β-catenin pathway and its components in various manifestations of ALD might provide insight in targeting the Wnt/β-catenin pathway in ALD treatment.

Moringa oleifera and Autophagy: Evidence from In Vitro Studies on Chaperone-Mediated Autophagy in HepG2 Cancer Cells

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer in Sub-Saharan African countries, including South Africa (SA). Given the limitations in current HCC therapeutics, there is an increasing need for alternative adjuvant therapeutic options. As such, several cell survival mechanisms, such as autophagy, have been identified as potential adjuvant therapeutic targets in HCC treatment. Of the three most established autophagic pathways, the upregulation of chaperone-mediated autophagy (CMA) has been extensively described in various cancer cells, including HCC cells. CMA promotes tumor growth and chemotherapeutic drug resistance, thus contributing to HCC tumorigenesis. Therefore, the modulation of CMA serves as a promising adjuvant target for current HCC therapeutic strategies. Phytochemical extracts found in the medicinal plant, Moringa oleifera (MO), have been shown to induce apoptosis in numerous cancer cells, including HCC. MO leaves have the greatest abundance of phytochemicals displaying anticancer potential. However, the potential interaction between the pro-apoptotic effects of MO aqueous leaf extract and the survival-promoting role of CMA in an in vitro model of HCC remains unclear. This review aims to summarize the latest findings on the role of CMA, and MO in the progression of HCC.

Oxidative Stress in Liver Pathophysiology and Disease

The liver is an organ that is particularly exposed to reactive oxygen species (ROS), which not only arise during metabolic functions but also during the biotransformation of xenobiotics. The disruption of redox balance causes oxidative stress, which affects liver function, modulates inflammatory pathways and contributes to disease. Thus, oxidative stress is implicated in acute liver injury and in the pathogenesis of prevalent infectious or metabolic chronic liver diseases such as viral hepatitis B or C, alcoholic fatty liver disease, non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). Moreover, oxidative stress plays a crucial role in liver disease progression to liver fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Herein, we provide an overview on the effects of oxidative stress on liver pathophysiology and the mechanisms by which oxidative stress promotes liver disease.

Alternatively-spliced lncRNA-PNUTS promotes HCC cell EMT via regulating ZEB1 expression

BACKGROUND

Long non-coding RNAs have been implicated in various cancers as they regulate critical cellular processes such as proliferation, migration, invasion, and apoptosis in tumorous tissues. lncRNA-PNUTS is newly reported as an alternatively-spliced lncRNA from PNUTS pre-mRNA that promotes oncogenesis in breast cancer. However, whether LncRNA-PNUTS plays a role in other forms of cancers, such as liver cancer, remains unknown.

METHOD

In the current study, we investigated the potential role of lncRNA-PNUTS in hepatocellular carcinoma (HCC). The levels of lncRNA-PNUTS in tumorous tissues obtained from HCC patients were measured. The potential impacts of lncPNUTS on metastasis and invasion were investigated through gain- or loss- of function experiments in cell models of liver cancers, as well as other cellular assays such as trans-well assays and wound-healing assays.

RESULTS

Here, we report that lncPNUTS was upregulated in human HCC tissues. Loss- and gain-of-function experiments indicated lncPNUTS promoted metastasis and invasion. In addition, ZEB1, which is involved in the activation of epithelial-mesenchymal-transition (EMT), was identified as a downstream target of lncPNUTS.

CONCLUSION

Our findings indicated lncPNUTS promotes HCC cancer cell metastasis and invasion via targeting ZEB1 to activate the EMT pathway, suggesting that lncPNUTS is a potential prognostic marker and therapeutic target for HCC patients.

Altered gut microbiota in hepatocellular carcinoma: Insights into the pathogenic mechanism and preclinical to clinical findings

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death worldwide. It is usually the result of pre-existing liver damage caused by hepatitis B and/or C virus infection, alcohol consumption, nonalcoholic steatohepatitis (NASH), aflatoxin exposure, liver cirrhosis, obesity, and diabetes. A growing body of evidence suggests that gut microbes have a role in cancer genesis. More research into the microbiome gut-liver axis has recently contributed to understanding how the gut microbiome facilitates liver disease or even HCC progression. This review focuses on the preclinical results of gut-related hepatocarcinogenesis and probiotics, prebiotics, and antibiotics as therapeutic interventions to maintain gut microbial flora and minimize HCC-associated symptoms. Understanding the mechanistic link between the gut microbiota, host, and cancer progression could aid us in elucidating the cancer-related pathways and drive us toward preventing HCC-associated gut microbiota dysbiosis.

Integrated Analysis of the Altered lncRNA, microRNA, and mRNA Expression in HBV-Positive Hepatocellular Carcinoma

Hepatitis B virus (HBV) infection is the most prominent risk factor for developing hepatocellular carcinoma (HCC), which can increase the incidence of HCC by more than 100 times. Accumulated evidence has revealed that non-coding RNAs (ncRNAs) play a regulatory role in various tumors through the long non-coding RNA (lncRNA)–microRNA (miRNA)–mRNA regulation axis. However, the involvement of the ncRNA regulatory network in the progression of HBV infection-induced HCC remains elusive. In the current work, five tumor samples from patients with hepatitis B surface antigen (HBsAg)-positive HCC and three tumor samples from patients with HBsAg-negative HCC were collected for whole-transcriptome sequencing. Between the two groups, 841 lncRNAs, 54 miRNAs, and 1118 mRNAs were identified to be differentially expressed (DE). The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that DE genes were mainly involved in cancer-related pathways, including Wnt and MAPK signaling pathways. The Gene Expression Omnibus (GEO) analysis further validated the selected DE mRNAs. The DE lncRNA–miRNA–mRNA network was built to explore the effect of HBV infection on the regulation of ncRNAs in HCC. These findings provide novel insights into the role of HBV infection in the progression of HCC.

HIV-1-Mediated Acceleration of Oncovirus-Related Non-AIDS-Defining Cancers

With the advent of combination antiretroviral therapy (cART), overall survival has been improved, and the incidence of acquired immunodeficiency syndrome (AIDS)-defining cancers has also been remarkably reduced. However, non-AIDS-defining cancers among human immunodeficiency virus-1 (HIV-1)-associated malignancies have increased significantly so that cancer is the leading cause of death in people living with HIV in certain highly developed countries, such as France. However, it is currently unknown how HIV-1 infection raises oncogenic virus-mediated cancer risks in the HIV-1 and oncogenic virus co-infected patients, and thus elucidation of the molecular mechanisms for how HIV-1 expedites the oncogenic viruses-triggered tumorigenesis in the co-infected hosts is imperative for developing therapeutics to cure or impede the carcinogenesis. Hence, this review is focused on HIV-1 and oncogenic virus co-infection-mediated molecular processes in the acceleration of non-AIDS-defining cancers.

Cohort study of familial viral hepatitis and risks of paediatric cancers

BACKGROUND

Although viral hepatitis causes paediatric hepatocellular carcinoma and hepatic and extrahepatic cancers in adults, there are few epidemiologic studies on paediatric-cancer risks from parental viral hepatitis. In a nationwide study in a viral hepatitis endemic region and with confirmation in another population-based sample, we examined associations between parental hepatitis B (HBV) and C (HCV) infections and risks of cancers in offspring.

METHODS

We included all children born in Taiwan in 2004-2014 (N = 2 079 037) with 2160 cancer cases ascertained from the Cancer Registry. We estimated risks for paediatric cancers using Cox proportional-hazard regressions. We checked these associations in a nationwide case-control study in Denmark (6422 cases, 160 522 controls).

RESULTS

In Taiwan, paternal HBV was related to child's hepatoblastoma [hazard ratio (HR) = 1.77, 95% confidence interval (CI) = 1.05, 2.97] when identified at any time in the medical record, and when analyses were limited to hepatitis diagnoses occurring before the child's birth, risks increased (HR = 2.08, 95% CI = 1.13-3.80). Paternal HCV was related to child's non-Hodgkin lymphoma (HR = 2.06, 95% CI = 1.13-3.74). Maternal HCV was weakly related to increased risks of all childhood cancers [all types combined; HR = 1.45, 95% CI = 0.95-2.22]. The population-attributable fraction of hepatoblastoma for maternal, paternal and child HBV was 2.6%, 6.8% and 2.8%, respectively.

CONCLUSIONS

Parental HBV and HCV may be risk factors for hepatic and non-hepatic cancers in children. If associations are causal, then parental screening and treatment with antivirals may prevent some paediatric cancers.

Hepatitis B x antigen (HBx) is an important therapeutic target in the pathogenesis of hepatocellular carcinoma

Hepatitis B virus (HBV) is a human pathogen that has infected an estimated two billion people worldwide. Despite the availability of highly efficacious vaccines, universal screening of the blood supply for virus, and potent direct acting anti-viral drugs, there are more than 250 million carriers of HBV who are at risk for the sequential development of hepatitis, fibrosis, cirrhosis and hepatocellular carcinoma (HCC). More than 800,000 deaths per year are attributed to chronic hepatitis B. Many different therapeutic approaches have been developed to block virus replication, and although effective, none are curative. These treatments have little or no impact upon the portions of integrated HBV DNA, which often encode the virus regulatory protein, HBx. Although given little attention, HBx is an important therapeutic target because it contributes importantly to (a) HBV replication, (b) in protecting infected cells from immune mediated destruction during chronic infection, and (c) in the development of HCC. Thus, the development of therapies targeting HBx, combined with other established therapies, will provide a functional cure that will target virus replication and further reduce or eliminate both the morbidity and mortality associated with chronic liver disease and HCC. Simultaneous targeting of all these characteristics underscores the importance of developing therapies against HBx.

In Vivo and In Vitro Models of Hepatocellular Carcinoma: Current Strategies for Translational Modeling

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and the third leading cause of cancer-related death globally. HCC is a complex multistep disease and usually emerges in the setting of chronic liver diseases. The molecular pathogenesis of HCC varies according to the etiology, mainly caused by chronic hepatitis B and C virus infections, chronic alcohol consumption, aflatoxin-contaminated food, and non-alcoholic fatty liver disease associated with metabolic syndrome or diabetes mellitus. The establishment of HCC models has become essential for both basic and translational research to improve our understanding of the pathophysiology and unravel new molecular drivers of this disease. The ideal model should recapitulate key events observed during hepatocarcinogenesis and HCC progression in view of establishing effective diagnostic and therapeutic strategies to be translated into clinical practice. Despite considerable efforts currently devoted to liver cancer research, only a few anti-HCC drugs are available, and patient prognosis and survival are still poor. The present paper provides a state-of-the-art overview of in vivo and in vitro models used for translational modeling of HCC with a specific focus on their key molecular hallmarks.

The phosphorylated retinoid X receptor-α promotes diethylnitrosamine-induced hepatocarcinogenesis in mice through the activation of β-catenin signaling pathway

Previous studies have shown that phosphorylation of the retinoid X receptor-α (RXRα) is associated with the development of hepatocellular carcinoma (HCC). However, these findings were revealed using HCC cell lines that express phosphorylated-RXRα (p-RXRα) proteins; therefore, it remains unclear whether p-RXRα affects hepatocarcinogenesis in vivo. Therefore, to investigate the biological function of p-RXRα in vivo, we developed a doxycycline-inducible ES cell line and transgenic mouse, both of which overexpress the phosphomimetic mutant form of RXRα, T82D/S260D, in a doxycycline-dependent manner. We found that the development of liver tumors, especially high-grade adenoma and HCC, was enhanced in diethylnitrosamine (DEN)-induced T82D/S260D-inducible mice. Moreover, the increased incidence of liver tumors in the transgenic mice was attributable to the promotion of cell cycle progression. Interestingly, the expression of β-catenin protein and its target gene cyclin D1 was elevated in the liver tumors of DEN-treated T82D/S260D-inducible mice, concurrent with increased cytoplasmic and nuclear β-catenin protein expression, indicating its stabilization and transcriptional activation. These results indicate that p-RXRα promotes DEN-induced hepatocarcinogenesis in mice through the activation of the β-catenin signaling pathway, suggesting that p-RXRα may serve as a possible therapeutic target for HCC.

Mechanisms of DNA Methylation in Virus-Host Interaction in Hepatitis B Infection: Pathogenesis and Oncogenetic Properties

Hepatitis B virus (HBV), the well-studied oncovirus that contributes to the majority of hepatocellular carcinomas (HCC) worldwide, can cause a severe inflammatory microenvironment leading to genetic and epigenetic changes in hepatocyte clones. HBV replication contributes to the regulation of DNA methyltransferase gene expression, particularly by X protein (HBx), and subsequent methylation changes may lead to abnormal transcription activation of adjacent genes and genomic instability. Undoubtedly, the altered expression of these genes has been known to cause diverse aspects of infected hepatocytes, including apoptosis, proliferation, reactive oxygen species (ROS) accumulation, and immune responses. Additionally, pollutant-induced DNA methylation changes and aberrant methylation of imprinted genes in hepatocytes also complicate the process of tumorigenesis. Meanwhile, hepatocytes also contribute to epigenetic modification of the viral genome to affect HBV replication or viral protein production. Meanwhile, methylation levels of HBV integrants and surrounding host regions also play crucial roles in their ability to produce viral proteins in affected hepatocytes. Both host and viral changes can provide novel insights into tumorigenesis, individualized responses to therapeutic intervention, disease progress, and early diagnosis. As such, DNA methylation-mediated epigenetic silencing of cancer-related genes and viral replication is a compelling therapeutic goal to reduce morbidity and mortality from liver cancer caused by chronic HBV infection. In this review, we summarize the most recent research on aberrant DNA methylation associated with HBV infection, which is involved in HCC development, and provide an outlook on the future direction of the research.

Biological Hallmarks and New Therapeutic Approaches for the Treatment of PDAC

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the deadliest solid tumors and is estimated to become a leading cause of cancer-related death in coming years. Despite advances in surgical approaches and the emergence of new chemotherapy options, its poor prognosis has not improved in the last decades. The current treatment for PDAC is the combination of cytotoxic chemotherapy agents. However, PDAC shows resistance to many antineoplastic therapies with rapid progression. Although PDAC represents a heterogeneous disease, there are common alterations including oncogenic mutations of KRAS, and the frequent inactivation of different cell cycle regulators including the CDKN2A tumor suppressor gene. An emerging field of investigation focuses on inhibiting the function of proteins that suppress the immune checkpoint PD-1/PD-L1, with activation of the endogenous immune response. To date, all conventional immunotherapies have been less successful in patients with PDAC compared to other tumors. The need for new targets, associated with an extended molecular analysis of tumor samples could give new pharmacological options for the treatment of PDAC. It is, therefore, important to push for a broader molecular approach in PDAC research. Here, we provide a selected summary of emerging strategy options for targeting PDAC using CDK4/6 inhibitors, RAS inhibitors, and new drug combinations with immune checkpoint agents.

Epigenetic Mechanisms Involved in HCV-Induced Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC), is the third leading cause of cancer-related deaths, which is largely caused by virus infection. About 80% of the virus-infected people develop a chronic infection that eventually leads to liver cirrhosis and hepatocellular carcinoma (HCC). With approximately 71 million HCV chronic infected patients worldwide, they still have a high risk of HCC in the near future. However, the mechanisms of carcinogenesis in chronic HCV infection have not been still fully understood, which involve a complex epigenetic regulation and cellular signaling pathways. Here, we summarize 18 specific gene targets and different signaling pathways involved in recent findings. With these epigenetic alterations requiring histone modifications and DNA hyper or hypo-methylation of these specific genes, the dysregulation of gene expression is also associated with different signaling pathways for the HCV life cycle and HCC. These findings provide a novel insight into a correlation between HCV infection and HCC tumorigenesis, as well as potentially preventable approaches. Hepatitis C virus (HCV) infection largely causes hepatocellular carcinoma (HCC) worldwide with 3 to 4 million newly infected cases diagnosed each year. It is urgent to explore its underlying molecular mechanisms for therapeutic treatment and biomarker discovery. However, the mechanisms of carcinogenesis in chronic HCV infection have not been still fully understood, which involve a complex epigenetic regulation and cellular signaling pathways. Here, we summarize 18 specific gene targets and different signaling pathways involved in recent findings. With these epigenetic alterations requiring histone modifications and DNA hyper or hypo-methylation of these specific genes, the dysregulation of gene expression is also associated with different signaling pathways for the HCV life cycle and HCC. These findings provide a novel insight into a correlation between HCV infection and HCC tumorigenesis, as well as potentially preventable approaches.

Identification and validation of three core genes in p53 signaling pathway in hepatitis B virus-related hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a common cancer and the leading cause is persistent hepatitis B virus (HBV) infection. We aimed to identify some core genes and pathways for HBV-related HCC.

METHODS

Gene expression profiles of GSE62232, GSE121248, and GSE94660 were available from Gene Expression Omnibus (GEO). The GSE62232 and GSE121248 profiles were the analysis datasets and GSE94660 was the validation dataset. The GEO2R online tool and Venn diagram software were applied to analyze commonly differentially expressed genes between HBV-related HCC tissues and normal tissues. Then, functional enrichment analysis using Gene Ontology (GO) and the Kyoto Encyclopedia of Gene and Genome (KEGG) as well as the protein-protein interaction (PPI) network was conducted. The overall survival rates and the expression levels were detected by Kaplan-Meier plotter and Gene Expression Profiling Interactive Analysis (GEPIA). Next, gene set enrichment analysis (GSEA) was performed to verify the KEGG pathway analysis. Furthermore, quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was performed to validate the levels of these three core genes in tumor tissues and adjacent non-tumor liver tissues from 12 HBV related HCC patients, HBV-associated liver cancer cell lines and normal liver cell lines, and HepG2 with p53 knockdown or deletion, respectively.

RESULTS

Fifteen highly expressed genes associated with significantly worse prognoses were selected and CCNB1, CDK1, and RRM2 in the p53 signaling pathway were identified as core genes. GSEA results showed that samples highly expressing three core genes were all enriched in the p53 signaling pathway in a validation dataset (P < 0.0001). The expression of these three core genes in tumor tissue samples was higher than that in relevant adjacent non-tumor liver tissues (P < 0.0001). Furthermore, we also found that the above genes were highly expressed in liver cancer cell lines compared with normal liver cells. In addition, we found that the expression of these three core genes in p53 knockdown or knockout HCC cell lines was lower than that in negative control HCC cell lines (P < 0.05).

CONCLUSIONS

CCNB1, CDK1, and RRM2 were enriched in the p53 signaling pathway and could be potential biomarkers and therapeutic targets for HBV-related HCC.

Risk Factors, Pathogenesis, and Strategies for Hepatocellular Carcinoma Prevention: Emphasis on Secondary Prevention and Its Translational Challenges

Hepatocellular carcinoma (HCC) is a leading cause of cancer-associated mortality globally. Given the limited therapeutic efficacy in advanced HCC, prevention of HCC carcinogenesis could serve as an effective strategy. Patients with chronic fibrosis due to viral or metabolic etiologies are at a high risk of developing HCC. Primary prevention seeks to eliminate cancer predisposing risk factors while tertiary prevention aims to prevent HCC recurrence. Secondary prevention targets patients with baseline chronic liver disease. Various epidemiological and experimental studies have identified candidates for secondary prevention-both etiology-specific and generic prevention strategies-including statins, aspirin, and anti-diabetic drugs. The introduction of multi-cell based omics analysis along with better characterization of the hepatic microenvironment will further facilitate the identification of targets for prevention. In this review, we will summarize HCC risk factors, pathogenesis, and discuss strategies of HCC prevention. We will focus on secondary prevention and also discuss current challenges in translating experimental work into clinical practice.

Investigation of CTNNB1 gene mutations and expression in hepatocellular carcinoma and cirrhosis in association with hepatitis B virus infection

Hepatitis B virus (HBV), along with Hepatitis C virus chronic infection, represents a major risk factor for hepatocellular carcinoma (HCC) development. However, molecular mechanisms involved in the development of HCC are not yet completely understood. Recent studies have indicated that mutations in CTNNB1 gene encoding for β-catenin protein lead to aberrant activation of the Wnt/ β-catenin pathway. The mutations in turn activate several downstream genes, including c-Myc, promoting the neoplastic process. The present study evaluated the mutational profile of the CTNNB1 gene and expression levels of CTNNB1 and c-Myc genes in HBV-related HCC, as well as in cirrhotic and control tissues. Mutational analysis of the β-catenin gene and HBV genotyping were conducted by direct sequencing. Expression of β-catenin and c-Myc genes was assessed using real-time PCR. Among the HCC cases, 18.1% showed missense point mutation in exon 3 of CTNNB1, more frequently in codons 32, 33, 38 and 45. The frequency of mutation in the hotspots of exon 3 was significantly higher in non-viral HCCs (29.4%) rather than HBV-related cases (12.7%, P = 0.021). The expression of β-catenin and c-Myc genes was found upregulated in cirrhotic tissues in association with HBV infection. Mutations at both phosphorylation and neighboring sites were associated with increased activity of the Wnt pathway. The results demonstrated that mutated β-catenin caused activation of the Wnt pathway, but the rate of CTNNB1 gene mutations was not related to HBV infection. HBV factors may deregulate the Wnt pathway by causing epigenetic alterations in the HBV-related HCC.

Lipid Metabolism in Development and Progression of Hepatocellular Carcinoma

: Metabolic reprogramming is critically involved in the development and progression of cancer. In particular, lipid metabolism has been investigated as a source of energy, micro-environmental adaptation, and cell signalling in neoplastic cells. However, the specific role of lipid metabolism dysregulation in hepatocellular carcinoma (HCC) has not been widely described yet. Alterations in fatty acid synthesis, β-oxidation, and cellular lipidic composition contribute to initiation and progression of HCC. The aim of this review is to elucidate the mechanisms by which lipid metabolism is involved in hepatocarcinogenesis and tumour adaptation to different conditions, focusing on the transcriptional aberrations with new insights in lipidomics and lipid zonation. This will help detect new putative therapeutic approaches in the second most frequent cause of cancer-related death.

Correlations between chromobox homolog 8 and key factors of epithelial-mesenchymal transition in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, especially in China, with high metastasis and poor prognosis. Recently, as the core component of the polycomb repressive complexes 1 (PRC1), chromobox protein homolog 8 (CBX8) is considered as an oncogene and prognostic marker in HCC.

Methods

A tissue microarray of 166 paired HCC and adjacent non-tumor samples were collected to identify the relationship between CBX8 and epithelial mesenchymal transition (EMT) associated proteins by Spearman correlation analysis. Knock-down of CBX8 in HCC cells was conducted to detect the biologic functions of CBX8 in HCC metastasis.

Results

We found out that CBX8 was over-expressed in HCC and its expression was closely related to the metastasis of HCC patients. In addition, knock-down of CBX8 was found to inhibit the invasion and migration ability of HCC cells. Moreover, there was a significant relationship between expression of CBX8 and EMT associated proteins both in HCC cells and tumor tissues.

Conclusions

Our results indicate that CBX8 promotes metastasis of HCC by inducing EMT process.

The Regulatory Role of MicroRNA in Hepatitis-B Virus-Associated Hepatocellular Carcinoma (HBV-HCC) Pathogenesis

The incidence and mortality of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HBV-HCC) is an intractable public health problem in developing countries that is compounded by limited early detection and therapeutic options. Despite the early promise of utilizing the regulatory role of miRNA in liver cancer, this field remains largely in the work-in-progress phase. This exploratory review paper adopts a broad focus in order to collate evidence of the regulatory role of miRNA in each stage of the HBV-HCC continuum. This includes the regulatory role of miRNA in early HBV infection, chronic inflammation, fibrosis/cirrhosis, and the onset of HCC. The paper specifically investigates HBV dysregulated miRNA that influence the expression of the host/HBV genome in HBV-HCC pathogenesis and fully acknowledges that this does not cover the full spectrum of dysregulated miRNA. The sheer number of dysregulated miRNA in each phase support a hypothesis that future therapeutic interventions will need to consider incorporating multiple miRNA panels.

A comprehensive genome-wide profiling comparison between HBV and HCV infected hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, especially in East Asia. Even with the progress in therapy, 5-year survival rates remain unsatisfied. Chronic infection with the hepatitis B virus (HBV) or hepatitis C virus (HCV) has been epidemiologically associated with HCC and is the major etiology in the East Asian population. The detailed mechanism, especially the changes of DNA methylation and gene expression between the two types of virus-related HCC, and their contributions to the HCC development, metastasis, and recurrence remain largely unknown.

METHODS

In this integrated analysis, we characterized genome-scale profiles of HBV and HCV infected HCC by comparing their gene expression pattern, methylation profiles, and copy number variations from the publicly accessible data of The Cancer Genome Atlas Program (TCGA).

RESULTS

The HLA-A, STAT1, and OAS2 genes were highly enriched and up-regulated discovered in the HCV-infected HCC. Hypomethylation but not copy number variations might be the major factor for the up-regulation of these immune-related genes in HCV-infected HCC.

CONCLUSIONS

The results indicated the different epigenetic changes of HBV/HCV related hepatocarcinogenesis. The top up-regulated genes in HCV group were significantly clustered in the immune-related and defense response pathways. These findings will help us to understand the pathogenesis of HBV/HCV associated hepatocellular carcinoma.

Transcriptome analysis identifies metallothionein as biomarkers to predict recurrence in hepatocellular cacinoma

BACKGROUND

Liver cancer is the fifth most common cancer, and hepatocellular carcinoma (HCC) is the major liver tumor type seen in adults. HCC is usually caused by chronic liver disease such as hepatitis B virus or hepatitis C virus infection. One of the promising treatments for HCC is liver transplantation, in which a diseased liver is replaced with a healthy liver from another person. However, recurrence of HCC after surgery is a significant problem. Therefore, it is important to discover reliable cellular biomarkers that can predict recurrence in HCC.

METHODS

We analyzed previously published HCC RNA-Seq data that includes 21 paired tumor and normal samples, in which nine tumors were recurrent after orthotopic liver transplantation and 12 were nonrecurrent tumors with their paired normal samples. We used both the reference genome and de novo transcriptome assembly based analyses to identify differentially expressed genes (DEG) and used RandomForest to discover biomarkers.

RESULTS

We obtained 398 DEG using the Reference approach and 412 DEG using de novo assembly approach. Among these DEG, 258 genes were identified by both approaches. We further identified 30 biomarkers that could predict the recurrence. We used another independent HCC study that includes 50 patients normal and tumor samples. By using these 30 biomarkers, the prediction accuracy was 100% for normal condition and 98% for tumor condition. A group of Metallothionein was specifically discovered as biomarkers in both reference and de novo assembly approaches.

CONCLUSION

We identified a group of Metallothionein genes as biomarkers to predict recurrence. The metallothionein genes were all down-regulated in tumor samples, suggesting that low metallothionein expression may be a promoter of tumor growth. In addition, using de novo assembly identified some unique biomarkers, further confirmed the necessity of conducting a de novo assembly in human cancer study.

Diet Supplementation with Soy Protein Isolate, but Not the Isoflavone Genistein, Protects Against Alcohol-Induced Tumor Progression in DEN-Treated Male Mice

Diethylnitrosamine-treated male mice were assigned to 4 groups: a casein-based 35% high fat ethanol liquid diet (EtOH), an EtOH diet made with soy protein isolate protein (EtOH/SOY), an EtOH liquid diet supplemented with genistein (EtOH/GEN) and a chow group. EtOH feeding, final concentration 5% (v/v), continued for 16 wks. EtOH increased incidence and multiplicity of basophilic lesions and adenomas compared to the chow group, (p < 0.05). The EtOH/SOY group had reduced adenoma progression when compared to the EtOH and EtOH/GEN group, (p < 0.05). Genistein supplementation had no protective effect. Soy feeding significantly reduced serum ALT concentrations (p < 0.05), decreased hepatic TNFα and CD-14 expression and decreased nuclear accumulation of NFκB protein in EtOH/SOY-treated mice compared to the EtOH group (p < 0.05). With respect to ceramides, high resolution MALDI-FTICR Imaging mass spectrometry revealed changes in the accumulation of long acyl chain ceramide species, in particular C18, in the EtOH group when compared to the EtOH/SOY group. Additionally, expression of acid ceramidase and sphingosine kinase 1 which degrade ceramide into sphingosine and convert sphingosine to sphingosine-1-phosphate (S1P) respectively and expression of S1P receptors S1PR2 and S1PR3 were all upregulated by EtOH and suppressed in the EtOH/SOY group, p < 0.05. EtOH feeding also increased hepatocyte proliferation and mRNA expression of β-catenin targets, including cyclin D1, MMP7 and glutamine synthase, which were reduced in the EtOH/SOY group, p < 0.05. These findings suggest that soy prevents tumorigenesis by reducing inflammation and by reducing hepatocyte proliferation through inhibition of EtOH-mediated β-catenin signaling. These mechanisms may involve blockade of sphingolipid signaling.

NCKAP1 improves patient outcome and inhibits cell growth by enhancing Rb1/p53 activation in hepatocellular carcinoma

In our previous report, we identified miR-34c-3p as an independent factor contributing to the carcinogenesis of hepatocellular carcinoma (HCC) by targeting NCK Associated Protein 1 (NCKAP1). NCKAP1 has been known to promote the malignancy of cancer cells by disrupting the structural stability of WAS protein family member 1 (WASF1) and is correlated with poor prognosis of patients in several cancer types. Our results, however, show that NCKAP1 is correlated with a favorable outcome in HCC patients. The underlying mechanism of this contradictory phenomenon is unknown. The current study was designed to explore the mechanism of NCKAP1 in HCC. As a result, clinicopathological correlations and results from in vivo and in vitro models indicated that NCKAP1 was a tumor suppressor gene. Cell cycle analysis suggested that NCKAP1 inhibit cells from entering G2/M phase. Western blot analysis showed that WASF1 was barely expressed in HCC cell lines compared to that of breast cancer cell lines, which serve as positive controls. Furthermore, Rb1 and p53 expression was upregulated in cell lines overexpressing NCKAP1. Expression of several cell cycle regulating proteins also varied in the HCC cell lines. In conclusion, although previous studies have identified NCKAP1 as a cell invasion promoter by binding to WASF1, we found that NCKAP1 is a tumor suppress gene that modulates the cell cycle of HCC cell lines by targeting Rb1/p53 regulation.

Heterogeneity and coexistence of oncogenic mechanisms involved in HCV-associated B-cell lymphomas

The association of HCV-infection with B-lymphomas is supported by the regression of most indolent/low-grade lymphomas following anti-viral therapy. Studies on direct and indirect oncogenic mechanisms have elucidated the pathogenesis of HCV-associated B-lymphoma subtypes. These include B-lymphocyte proliferation and sustained clonal expansion by HCV-envelope protein stimulation of B-cell receptors, and prolonged HCV-infected B-cell growth by overexpression of an anti-apoptotic BCL-2 oncogene caused by the increased frequency of t(14;18) chromosomal translocations in follicular lymphomas. HCV has been implicated in lymphomagenesis by a "hit-and-run" mechanism, inducing enhanced mutation rate in immunoglobulins and anti-oncogenes favoring immune escape, due to permanent genetic damage by double-strand DNA-breaks. More direct oncogenic mechanisms have been identified in cytokines and chemokines in relation to NS3 and Core expression, particularly in diffuse large B-cell lymphoma. By reviewing genetic alterations and disrupted signaling pathways, we intend to highlight how mutually non-contrasting mechanisms cooperate with environmental factors toward progression of HCV-lymphoma.

The clinical significance of microRNA-122 in predicting the prognosis of patients with hepatocellular carcinoma: A meta-analysis validated by the Cancer Genome Atlas dataset

BACKGROUND

Although the prognostic value of microRNA-122 (miR-122) for hepatocellular carcinoma (HCC) patients have been evaluated by numerous studies, the results of them were not completely consistent. The present study aims to comprehensively evaluate the predicting value of miR-122 on the prognosis of patients with HCC based on all eligible literatures.

METHODS

Numerous electronic databases (MEDLINE, Embase, Pubmed, Google Scholar, and China Biology Medicine disc) were applied to retrieve relevant studies. Overall survival (OS) and progression-free survival (PFS) were used as primary endpoints. All statistical analyses were performed by RevMan software version 5.3.5 and STATA software version 14.1. In addition, the results of this meta-analysis were validated by an independent dataset from the Cancer Genome Atlas (TCGA).

RESULTS

A total of 11 studies containing 1124 patients were included in this meta-analysis. The pooled results showed that low miR-122 expression in HCC tissues significantly associated with unfavorable OS (hazard ratio [HR] = 1.48, 95% confidence interval [CI] 1.22-1.80, P < .001) and PFS (HR = 1.54, 95% CI 1.28-1.85, P < .001) in patients with HCC. However, the expression level of miR-122 in blood did not have the ability in predicting OS (HR = 0.75, 95% CI 0.44-1.28, P = .29) and PFS (HR = 0.84, 95% CI 0.58-1.20, P = .33) of HCC. Subgroup analysis further indicated that low expression of miR-122 in tumor tissues predicted poor OS in HCC patients who received curative liver resection (HR = 2.00, 95% CI 1.08-3.70, P = .03). Analysis using TCGA dataset suggested that low miR-122 expression in HCC tissues was significantly associated with OS (HR = 1.61, 95% CI 1.13-2.27, P = .008) other than PFS (HR = 1.30, 95% CI 0.96-1.75, P = .09).

CONCLUSION

Low miR-122 expression in HCC tissues was a reliable indicator for predicting the OS of HCC patients who underwent curative resection. Owing to the disagreement between this meta-analysis and the TCGA dataset, the predictive value of miR-122 in tissues for PFS needs to be verified by future well-designed studies with large sample size.

CDKN2A promoter methylation and hepatocellular carcinoma risk: A meta-analysis

AIM

Lots of studies have explored cyclin-dependent kinase inhibitor 2A (CDKN2A) promoter methylation in hepatocellular carcinoma (HCC), but the established results were controversial. Hence, we conducted the meta-analysis to comprehensively investigate the association between CDKN2A promoter methylation and HCC risk.

METHODS

A comprehensive search was implemented through searching PubMed, Web of Science and Embase. Associations of CDKN2A promoter methylation with HCC risk, clinicopathological features, and CDKN2A expression were assessed by the pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs). Subgroup analyses and meta-regression were served for exploring the potential sources of heterogeneity.

RESULTS

A total of 59 articles including 3067 cases and 2951 controls were incorporated in this meta-analysis. Overall, we observed a high CDKN2A promoter methylation rate (58.18%) in HCC and a significant association between the methylation and HCC risk (OR, 7.07; 95% CI, 5.67-8.80). Furthermore, CDKN2A promoter methylation was robustly associated with decreased mRNA (OR, 13.89; 95% CI, 5.44-35.45) and protein (OR, 48.19; 95% CI, 5.56-417.29). In addition, we found the methylation was related with HBV infection (OR, 3.31; 95% CI, 1.47-7.47), HCV infection (OR, 2.76; 95% CI, 1.80-4.23), cirrhosis status (OR, 1.57; 95% CI, 1.01-2.44) and older age (OR, 1.83; 95% CI, 1.14-2.94).

CONCLUSIONS

Our results indicated that CDKN2A promoter methylation was associated with an enhancive HCC risk and played a crucial role in the process of HCC with a potential value to being a triage marker for HCC.

MicroRNA Profile in Peripheral Blood Mononuclear Cells from Hepatitis B Virus Infected Patients

INTRODUCTION AND AIM

The pathogenesis of hepatitis B virus (HBV)-related liver diseases remains not fully understood. Here, we aim to explore the potential roles of dysregulated miRNAs in chronic hepatitis B (CHB) and HBV-related acute-on-chronic liver failure (ACLF).

MATERIAL AND METHODS

MiRNA microarray was conducted in peripheral blood mononuclear cells (PBMCs) obtained from healthy donors or patients with CHB or ACLF. Altered expression of miRNAs was further confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) analysis. Finally, the differentially expressed miRNAs and their target genes were subjected to bioinformatics analysis.

RESULTS

The miRNA microarray identified 45 up-regulated and 62 down-regulated miRNAs with a fold change ≥ 1.5. Expression of eight miRNAs was validated using qRT-PCR analysis, which was consistent with miRNA microarray analysis. Bioinformatics analysis indicated that multiple biological processes and signaling pathways were affected by these miRNAs and a miRNA-gene regulatory network was generated with Cytoscape.

CONCLUSION

The current study provided a global view of miRNA expression in PBMCs from CHB and ACLF patients. Functional analysis showed that multiple biological processes and signaling pathways were modulated by these miRNAs. These data provide intriguing insights into the molecular pathogenesis of HBVrelated liver diseases, which deserve further investigation.

Aflatoxin B1 residues in human livers and their relationship with markers of hepatic carcinogenesis in São Paulo, Brazil

In this study, hepatic biopsies from autopsy cases in São Paulo, Brazil, showing hepatocellular carcinoma (HCC, n = 8), cirrhosis associated with viral hepatitis (VC, n = 20), cirrhosis associated with alcoholism (AC, n = 20), and normal livers (NL or controls, n = 10) were subjected to determination of aflatoxin B1 (AFB1) and its main metabolites, and of markers of hepatic carcinogenesis Only non-metabolized AFB1 was detected in 13 samples (27.1%, N = 48) of liver disorders (HCC, VC and AC), at levels between 10.0 and 418.0 pg/g (mean: 76.6 ± 107.7 pg/g). Immuno-labeling of p53, cyclin D1, p21, β-catenin, and Prohibitin (PB) increased mainly in HCC patients, in relation to the controls. AFB1+ samples of HCC presented higher expressions of p53, cyclin D1, p21, and β-catenin compared with AFB1-livers. In contrast, p27, p16, and Rb immuno-labeling decreased in HCC, VC, and AC samples, compared with NL, with lowest values in AFB1+ samples for all liver disorders. Compared with NL, gene expression of cyclin D1 and PB in AFB1+ samples of HCC and AC were also higher, along with higher gene expression of p21 in VC and AC AFB1+ livers. Results indicated that patients with liver disorders were exposed to dietary aflatoxins, and that residual AFB1 in liver negatively affected the p53 and protein Rb pathways in HCC. Moreover, the presence of AFB1 in cirrhotic livers warrants concern about the potential contribution of dietary aflatoxin to disease progression during VC and AC.

MDM2-p53 Interactions in Human Hepatocellular Carcinoma: What Is the Role of Nutlins and New Therapeutic Options?

Human hepatocellular carcinoma (HCC) is the fifth most common cancer and is associated with poor prognosis worldwide. The molecular mechanisms underlying the pathogenesis of HCC have been an area of continuing interest, and recent studies using next generation sequencing (NGS) have revealed much regarding previously unsettled issues. Molecular studies using HCC samples have been mainly targeted with the aim to identify the fundamental mechanisms contributing to HCC and identify more effective treatments. In response to cellular stresses (e.g., DNA damage or oncogenes), activated p53 elicits appropriate responses that aim at DNA repair, genetic stability, cell cycle arrest, and the deletion of DNA-damaged cells. On the other hand, the murine double minute 2 (MDM2) oncogene protein is an important cellular antagonist of p53. MDM2 negatively regulates p53 activity through the induction of p53 protein degradation. However, current research has shown that the mechanisms underlying MDM2-p53 interactions are more complex than previously thought. Microarray data have added new insight into the transcription changes in HCC. Recently, Nutlin-3 has shown potency against p53-MDM2 binding and the enhancement of p53 stabilization as well as an increment of p53 cellular accumulation with potential therapeutic effects. This review outlines the molecular mechanisms involved in the p53-MDM2 pathways, the biological factors influencing these pathways, and their roles in the pathogenesis of HCC. It also discusses the action of Nutlin-3 treatment in inducing growth arrest in HCC and elaborates on future directions in research in this area. More research on the biology of p53-MDM2 interactions may offer a better understanding of these mechanisms and discover new biomarkers, sensitive prognostic indicators as well as new therapeutic interventions in HCC.

Downregulation of miR-200a-3p induced by hepatitis B Virus X (HBx) Protein promotes cell proliferation and invasion in HBV-infection-associated hepatocarcinoma

BACKGROUND

Hepatitis B Virus X (HBx) Protein encoded by HBV is believed to be the major player in the process of HBV-induced oncogenesis. Ectopic expression of miR-200a-3p was reported to be associated with diverse tumorigenesis. This study aimed to better understand the role of miR-200a-3p and its correlation with HBx in HBV-induced hepatocellular carcinoma (HCC).

METHODS

In this report, we examined the gene expression using quantitative RT-PCR and protein expression using Western blotting analysis. Cells were transfected with miR-200a-3p mimics or empty vector, and HBx-carrying vector or empty vector. Cell viability was tested using CCK-8 assay. Wound healing assay was performed to assess cell migration while Transwell assay was performed to evaluate cell invasion.

RESULTS

miR-200a-3p was downregulated in HBV-positive tissue samples compared with HBV-negative tissue samples. This result was further confirmed with HBV-positive and - negative cell lines. HBx protein was overexpressed in HBV-positive cells where expression of miR-200a-3p was significantly suppressed. Increased cell viability, altered cell cycle progression, increased cell migration and invasion occurred in HBx-overexpressed cells compared to its controls. In forced expressed miR-200a-3p cells, cell viability, cell migration and invasion were significantly decreased, and cell cycle status was altered compared to its controls.

CONCLUSIONS

Taken together, pathogenetic function of HBx is negatively correlated with miR-200a-3p in HBV-cased HCC through regulating cell viability, cell cycle arrest, cell migration and cell invasion.

p16 Methylation was associated with the development, age, hepatic viruses infection of hepatocellular carcinoma, and p16 expression had a poor survival: A systematic meta-analysis (PRISMA)

BACKGROUND

Loss of tumor suppressor gene p16 expression via promoter methylation has been reported in hepatocellular carcinoma (HCC). This meta-analysis was conducted to evaluate the correlation between p16 methylation and HCC. Additionally, we also analyzed the potential prognostic role of p16 methylation, expression or alteration-associated HCC.

METHODS

Online databases based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline were performed to analyze the role of p16 gene in HCC. The combined odds ratios (ORs) or hazard ratios (HRs) and their 95% confidence intervals (95% CIs) were summarized.

RESULTS

Final 3105 HCCs and 808 non-tumor controls (chronic hepatitis and liver cirrhosis) were performed in this meta-analysis. p16 promoter methylation in HCC was significantly higher than in chronic hepatitis and chronic hepatitis in tissue and blood samples. In addition, p16 promoter methylation was notably higher in patients >50 years' old than in patients aged <50 years, and it was higher in hepatitis B virus (HBV) or hepatitis C virus (HCV)-positive HCC than in hepatic viruses-negative HCC. However, p16 promoter methylation was not correlated with sex, cirrhosis, tumor differentiation, clinical stage. No association was found between p16 methylation or alteration and the prognosis of patients with HCC in overall survival (OS) and disease-free survival (DFS). Although p16 expression was significantly correlated with a poor prognosis in OS and DFS (P < .05) CONCLUSIONS:: Our results indicate that p16 methylation was linked to the development, age, HBV, and HCV infection of HCC. p16 methylation or alteration was not associated with the prognosis, but p16 expression was linked to a poor survival.

Bioinformatics analysis of key genes and pathways for hepatocellular carcinoma transformed from cirrhosis

OBJECTIVE

We aimed to identify some pivotal genes and pathways for hepatocellular carcinoma (HCC) transformation from cirrhosis and explore potential targets for treatment of the disease.

METHODS

The GSE17548 microarray data were downloaded from Gene Expression Omnibus database, and 37 samples (20 cirrhosis and 17 HCC samples) were used for analysis. The differentially expressed genes (DEGs) in HCC tissues were compared with those in cirrhosis tissues and analyzed using the limma package. Gene ontology-biological process and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analyses were performed using ClueGO and CluePedia tool kits, and the key KEGG pathway was analyzed using the R package pathview. The regulatory factor miRNA of DEGs was extracted from 3 verified miRNAs-target databases using the multiMiR R package. Moreover, a protein-protein interaction (PPI) network was constructed using the Cytoscape software.

RESULTS

DEGs including cyclin-dependent Kinase 1 (CDK1), PDZ-binding kinase (PBK), ribonucleotide reductase M2 (RRM2), and abnormal spindle homolog, and microcephaly-associated drosophila (ASPM) were the hub proteins with higher degrees in the PPI network. The cell cycle pathway (CDK1 enriched) and p53 signaling pathway (CDK1 and RRM2 enriched) were significantly enriched by DEGs.

CONCLUSION

CDK1, PBK, RRM2, and ASPM may be key genes for HCC transformation from cirrhosis. Furthermore, cell cycle and p53 signaling pathways may play vital mediatory roles; CDK1 may play crucial roles in HCC transformed from cirrhosis via cell cycle and p53 signaling pathways, and RRM2 might be involved in HCC transformed from cirrhosis via the p53 signaling pathway.

Pre-clinical and clinical investigations of metabolic zonation in liver diseases: The potential of microphysiology systems

The establishment of metabolic zonation within a hepatic lobule ascribes specific functions to hepatocytes based on unique, location-dependent gene expression patterns. Recently, there have been significant developments in the field of metabolic liver zonation. A little over a decade ago, the role of β-catenin signaling was identified as a key regulator of gene expression and function in pericentral hepatocytes. Since then, additional molecules have been identified that regulate the pattern of Wnt/β-catenin signaling within a lobule and determine gene expression and function in other hepatic zones. Currently, the molecular basis of metabolic zonation in the liver appears to be a 'push and pull' between signaling pathways. Such compartmentalization not only provides an efficient assembly line for hepatocyte functions but also can account for restricting the initial hepatic damage and pathology from some hepatotoxic drugs to specific zones, possibly enabling effective regeneration and restitution responses from unaffected cells. Careful analysis and experimentation have also revealed that many pathological conditions in the liver lobule are spatially heterogeneous. We will review current research efforts that have focused on examination of the role and regulation of such mechanisms of hepatocyte adaptation and repair. We will discuss how the pathological organ-specific microenvironment affects cell signaling and metabolic liver zonation, especially in steatosis, viral hepatitis, and hepatocellular carcinoma. We will discuss how the use of new human microphysiological platforms will lead to a better understanding of liver disease progression, diagnosis, and therapies. In conclusion, we aim to provide insights into the role and regulation of metabolic zonation and function using traditional and innovative approaches. Impact statement Liver zonation of oxygen tension along the liver sinusoids has been identified as a critical liver microenvironment that impacts specific liver functions such as intermediary metabolism of amino acids, lipids, and carbohydrates, detoxification of xenobiotics and as sites for initiation of liver diseases. To date, most information on the role of zonation in liver disease including, non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma (HCC) have been obtained from animal models. It is now possible to complement animal studies with human liver, microphysiology systems (MPS) containing induced pluripotent stem cells engineered to create disease models where it is also possible to control the in vitro liver oxygen microenvironment to define the role of zonation on the mechanism(s) of disease progression. The field now has the tools to investigate human liver disease progression, diagnosis, and therapeutic development.

Hepatitis B virus X protein-mediated non-coding RNA aberrations in the development of human hepatocellular carcinoma

Hepatitis B virus (HBV) has an important role in the development of human hepatocellular carcinoma (HCC). Accumulated evidence has shown that HBV-encoded X protein (HBx) can induce both genetic alterations in tumor suppressor genes and oncogenes, as well as epigenetic aberrations in HCC pathogens. Non-coding RNAs (ncRNAs) mainly include microRNAs and long non-coding RNAs (lncRNAs). Although ncRNAs cannot code proteins, growing evidence has shown that they have various important biological functions in cell proliferation, cell cycle control, anti-apoptosis, epithelial–mesenchymal transition, tumor invasion and metastasis. This review summarizes the current knowledge regarding the mechanisms and emerging roles of ncRNAs in the pathogenesis of HBV-related HCC. Accumulated data have shown that ncRNAs regulated by HBx have a crucial role in HBV-associated hepatocarcinogenesis. The findings of these studies will contribute to more clinical applications of HBV-related ncRNAs as potential diagnostic markers or as molecular therapeutic targets to prevent and treat HBV-related HCC.

Soy protein isolate inhibits hepatic tumor promotion in mice fed a high-fat liquid diet

Alcoholic and nonalcoholic fatty liver diseases are risk factors for development of hepatocellular carcinoma, but the underlying mechanisms are poorly understood. On the other hand, ingestion of soy-containing diets may oppose the development of certain cancers. We previously reported that replacing casein with a soy protein isolate reduced tumor promotion in the livers of mice with alcoholic liver disease after feeding a high fat ethanol liquid diet following initiation with diethylnitrosamine. Feeding soy protein isolate inhibited processes that may contribute to tumor promotion including inflammation, sphingolipid signaling, and Wnt/β-catenin signaling. We have extended these studies to characterize liver tumor promotion in a model of nonalcoholic fatty liver disease produced by chronic feeding of high-fat liquid diets in the absence of ethanol. Mice treated with diethylnitrosamine on postnatal day 14 were fed a high-fat liquid diet made with casein or SPI as the sole protein source for 16 weeks in adulthood. Relative to mice fed normal chow, a high fat/casein diet led to increased tumor promotion, hepatocyte proliferation, steatosis, and inflammation. Replacing casein with soy protein isolate counteracted these effects. The high fat diets also resulted in a general increase in transcripts for Wnt/β-catenin pathway components, which may be an important mechanism, whereby hepatic tumorigenesis is promoted. However, soy protein isolate did not block Wnt signaling in this nonalcoholic fatty liver disease model. We conclude that replacing casein with soy protein isolate blocks development of steatosis, inflammation, and tumor promotion in diethylnitrosamine-treated mice fed high fat diets. Impact statement The impact of dietary components on cancer is a topic of great interest for both the general public and the scientific community. Liver cancer is currently the second leading form of cancer deaths worldwide. Our study has addressed the effect of the protein source on hepatic tumor promotion in a mouse model reflecting aspects of non-alcoholic fatty liver disease (NAFLD). A high-fat liquid diet with casein as the protein source promotes hepatic injury and tumor promotion in diethylnitrosamine-treated mice. Replacing casein with a soy protein isolate led to a pronounced diminishment of tumor promotion and associated hepatic injury and inflammation. The study thus demonstrates that a dietary protein source can have beneficial, preventative effects on hepatic tumor promotion.

Action and function of Wnt/β-catenin signaling in the progression from chronic hepatitis C to hepatocellular carcinoma

Hepatitis C virus (HCV) infection is one of the leading causes of hepatocellular carcinoma (HCC) worldwide but the mechanistic basis as to how chronic HCV infection furthers the HCC process remains only poorly understood. Accumulating evidence indicates that HCV core and nonstructural proteins provoke activation of the Wnt/β-catenin signaling pathway, and the evidence supporting a role of Wnt/β-catenin signaling in the onset and progression of HCC is compelling. Convincing molecular explanations as to how expression of viral effectors translates into increased activity of the Wnt/β-catenin signaling machinery are still largely lacking, hampering the design of rational strategies aimed at preventing HCC. Furthermore, how such increased signaling is especially associated with HCC oncogenesis in the context of HCV infection remains obscure as well. Here we review the body of contemporary biomedical knowledge on the role of the Wnt/β-catenin pathway in the progression from chronic hepatitis C to cirrhosis and HCC and explore potential hypotheses as to the mechanisms involved.

Hepatoepigenetic Alterations in Viral and Nonviral-Induced Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a major public health concern and one of the leading causes of tumour-related deaths worldwide. Extensive evidence endorses that HCC is a multifactorial disease characterised by hepatic cirrhosis mostly associated with chronic inflammation and hepatitis B/C viral infections. Interaction of viral products with the host cell machinery may lead to increased frequency of genetic and epigenetic aberrations that cause harmful alterations in gene transcription. This may provide a progressive selective advantage for neoplastic transformation of hepatocytes associated with phenotypic heterogeneity of intratumour HCC cells, thus posing even more challenges in HCC treatment development. Epigenetic aberrations involving DNA methylation, histone modifications, and noncoding miRNA dysregulation have been shown to be intimately linked with and play a critical role in tumour initiation, progression, and metastases. The current review focuses on the aberrant hepatoepigenetics events that play important roles in hepatocarcinogenesis and their utilities in the development of HCC therapy.

Accumulation of Deleterious Passenger Mutations Is Associated with the Progression of Hepatocellular Carcinoma

In hepatocellular carcinoma (HCC), somatic genome-wide DNA mutations are numerous, universal and heterogeneous. Some of these somatic mutations are drivers of the malignant process but the vast majority are passenger mutations. These passenger mutations can be deleterious to individual protein function but are tolerated by the cell or are offset by a survival advantage conferred by driver mutations. It is unknown if these somatic deleterious passenger mutations (DPMs) develop in the precancerous state of cirrhosis or if it is confined to HCC. Therefore, we studied four whole-exome sequencing datasets, including patients with non-cirrhotic liver (n = 12), cirrhosis without HCC (n = 6) and paired HCC with surrounding non-HCC liver (n = 74 paired samples), to identify DPMs. After filtering out putative germline mutations, we identified 187±22 DPMs per non-diseased tissue. DPMs number was associated with liver disease progressing to HCC, independent of the number of exonic mutations. Tumours contained significantly more DPMs compared to paired non-tumour tissue (258-293 per HCC exome). Cirrhosis- and HCC-associated DPMs do not occur predominantly in specific genes, chromosomes or biological pathways and the effect on tumour biology is presently unknown. Importantly, for the first time we have shown a significant increase in DPMs with HCC.

The Wnt pathway: a key network in cell signalling dysregulated by viruses

Viruses are obligate parasites dependent on host cells for survival. Viral infection of a cell activates a panel of pattern recognition receptors that mediate antiviral host responses to inhibit viral replication and dissemination. Viruses have evolved mechanisms to evade and subvert this antiviral host response, including encoding proteins that hijack, mimic and/or manipulate cellular processes such as the cell cycle, DNA damage repair, cellular metabolism and the host immune response. Currently, there is an increasing interest whether viral modulation of these cellular processes, including the cell cycle, contributes to cancer development. One cellular pathway related to cell cycle signalling is the Wnt pathway. This review focuses on the modulation of this pathway by human viruses, known to cause (or associated with) cancer development. The main mechanisms where viruses interact with the Wnt pathway appear to be through (i) epigenetic modification of Wnt genes; (ii) cellular or viral miRNAs targeting Wnt genes; (iii) altering specific Wnt pathway members, often leading to (iv) nuclear translocation of β-catenin and activation of Wnt signalling. Given that diverse viruses affect this signalling pathway, modulating Wnt signalling could be a generalised critical process for the initiation or maintenance of viral pathogenesis, with resultant dysregulation contributing to virus-induced cancers. Further study of this virus-host interaction may identify options for targeted therapy against Wnt signalling molecules as a means to reduce virus-induced pathogenesis and the downstream consequences of infection. Copyright © 2016 John Wiley & Sons, Ltd.

Selective Retention of an Inactive Allele of the DKK2 Tumor Suppressor Gene in Hepatocellular Carcinoma

In an effort to identify the functional alleles associated with hepatocellular carcinoma (HCC), we investigated 152 genes found in the 4q21-25 region that exhibited loss of heterozygosity (LOH). A total of 2,293 pairs of primers were designed for 1,449 exonic and upstream promoter regions to amplify and sequence 76.8–114 Mb on human chromosome 4. Based on the results from analyzing 12 HCC patients and 12 healthy human controls, we discovered 1,574 sequence variations. Among the 99 variants associated with HCC (p < 0.05), four are from the Dickkopf 2 (DKK2) gene: three in the promoter region (g.-967A>T, g.-923C>A, and g.-441T>G) and one in the 5’UTR (c.550T>C). To verify the results, we expanded the subject cohort to 47 HCC cases and 88 healthy controls for conducting haplotype analysis. Eight haplotypes were detected in the non-tumor liver tissue samples, but one major haplotype (TAGC) was found in the tumor tissue samples. Using a reporter assay, this HCC-associated allele registered the lowest level of promoter activity among all the tested haplotype sequences. Retention of this allele in LOH was associated with reduced DKK2 transcription in the HCC tumor tissues. In HuH-7 cells, DKK2 functioned in the Wnt/β-catenin signaling pathway, as an antagonist of Wnt3a, in a dose-dependent manner that inhibited Wnt3a-induced cell proliferation. Taken together, the genotyping and functional findings are consistent with the hypothesis that DKK2 is a tumor suppressor; by selectively retaining a transcriptionally inactive DKK2 allele, the reduction of DKK2 function results in unchecked Wnt/β-catenin signaling, contributing to HCC oncogenesis. Thus our study reveals a new mechanism through which a tumor suppressor gene in a LOH region loses its function by allelic selection.

Liver cancer is one of the most lethal human cancers. Identifying functional alleles associated with liver cancer can provide new insights into the disease’s pathogenesis and help to advance the development of new therapeutic approaches. We conducted re-sequencing of the 4q21-25 region that frequently showed loss of heterozygosity (LOH) in liver cancer. Among the 99 variants associated with liver cancer, four are found within the Dickkopf 2 (DKK2) gene. We conducted haplotype analysis of the DKK2 promoter sequence and found that a transcriptionally inactive DKK2 allele was selectively retained in the tumor tissues. Additionally, by sequencing individual molecular clones, we detected 7-mer CCTCCCT sites within the DKK2 promoter region that are involved in PRDM9 binding, pinpointing hotspots for recombination and genome instability. Furthermore, we demonstrated that DKK2 functioned as an antagonist within the Wnt/β-catenin signaling pathway. Our findings have led to the discovery of a new mechanism whereby a tumor suppressor gene in a LOH region loses its function by allelic selection.

Genome-wide DNA methylation analysis in hepatocellular carcinoma

Epigenetic changes as well as genetic changes are mechanisms of tumorigenesis. We aimed to identify novel genes that are silenced by DNA hypermethylation in hepatocellular carcinoma (HCC). We screened for genes with promoter DNA hypermethylation using a genome-wide methylation microarray analysis in primary HCC (the discovery set). The microarray analysis revealed that there were 2,670 CpG sites that significantly differed in regards to the methylation level between the tumor and non-tumor liver tissues; 875 were significantly hypermethylated and 1,795 were significantly hypomethylated in the HCC tumors compared to the non‑tumor tissues. Further analyses using methylation-specific PCR, combined with expression analysis, in the validation set of primary HCC showed that, in addition to three known tumor-suppressor genes (APC, CDKN2A, and GSTP1), eight genes (AKR1B1, GRASP, MAP9, NXPE3, RSPH9, SPINT2, STEAP4, and ZNF154) were significantly hypermethylated and downregulated in the HCC tumors compared to the non-tumor liver tissues. Our results suggest that epigenetic silencing of these genes may be associated with HCC.

Soy Protein Isolate Protects Against Ethanol-Mediated Tumor Progression in Diethylnitrosamine-Treated Male Mice

In this study, diethylnitrosamine-treated male mice were assigned to three groups: (i) a 35% high fat ethanol liquid diet (EtOH) with casein as the protein source, (ii) the same EtOH liquid diet with soy protein isolate as the sole protein source (EtOH/SPI), (iii) and a chow group. EtOH feeding continued for 16 weeks. As expected, EtOH increased the incidence and multiplicity of basophilic lesions and adenomas compared with the chow group, P < 0.05. Soy protein replacement of casein in the EtOH diet significantly reduced adenoma progression when compared with the EtOH and EtOH/SPI group (P < 0.05). Tumor reduction in the EtOH/SPI group corresponded to reduced liver injury associated with decreased hepatic Tnfα and Cd14 antigen (Cd14) expression and decreased nuclear accumulation of NF-κB1 protein compared with the EtOH group (P < 0.05). Detection of sphingolipids using high-resolution matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance (MALDI-FTICR) imaging mass spectrometry revealed increased accumulation of long acyl chain ceramide species, and sphingosine-1-phosphate (S1P) in the EtOH group that were significantly reduced in the EtOH/SPI group. Chronic EtOH feeding also increased mRNA expression of β-catenin transcriptional targets, including cyclin D1 (Ccnd1), matrix metallopeptidase 7 (Mmp7), and glutamine synthetase (Glns), which were reduced in the EtOH/SPI group (P < 0.05). We conclude that soy prevents tumorigenesis by reducing proinflammatory and oxidative environment resulting from EtOH-induced hepatic injury, and by reducing hepatocyte proliferation through inhibition of β-catenin signaling. These mechanisms may involve changes in sphingolipid signaling. Cancer Prev Res; 9(6); 466-75. ©2016 AACR.

E-cadherin can limit the transforming properties of activating β-catenin mutations

Wnt pathway deregulation is a common characteristic of many cancers. Only colorectal cancer predominantly harbours mutations in APC, whereas other cancer types (hepatocellular carcinoma, solid pseudopapillary tumours of the pancreas) have activating mutations in β-catenin (CTNNB1). We have compared the dynamics and the potency of β-catenin mutations in vivo. Within the murine small intestine (SI), an activating mutation of β-catenin took much longer to achieve Wnt deregulation and acquire a crypt-progenitor cell (CPC) phenotype than Apc or Gsk3 loss. Within the colon, a single activating mutation of β-catenin was unable to drive Wnt deregulation or induce the CPC phenotype. This ability of β-catenin mutation to differentially transform the SI versus the colon correlated with higher expression of E-cadherin and a higher number of E-cadherin:β-catenin complexes at the membrane. Reduction in E-cadherin synergised with an activating mutation of β-catenin resulting in a rapid CPC phenotype within the SI and colon. Thus, there is a threshold of β-catenin that is required to drive transformation, and E-cadherin can act as a buffer to sequester mutated β-catenin.

Downregulation of N-myc downstream regulated gene 1 caused by the methylation of CpG islands of NDRG1 promoter promotes proliferation and invasion of prostate cancer cells

Current studies tend to consider N-myc downstream regulated gene 1 (NDRG1) as a tumor suppressor gene, inhibiting cell proliferation and invasion. NDRG1 expression in cancer cells is generally low, but the molecular mechanism is unclear. Aberrant methylation of CpG islands (CGIs) in gene promoter was able to inactivate tumor suppressor genes and activate oncogenes, disordering cell proliferation and apoptosis, playing a promotion role in tumor occurrence and progression. The present study was performed to investigate the effect of epigenetic modification of NDRG1 on prostate cancer (PCa) cells. The protein expression in human specimens was measured by immunohistochemical staining. The expression level of NDRG1 was changed by plasmid vectors in PCa cells. These cells were used to study proliferation and invasiveness. NDRG1 expression in normal prostate cells was higher than that in PCa cells. Downregulation of NDRG1 expression enhanced cell proliferation and invasiveness. In contrast, its upregulation could reduce cell proliferation and invasiveness. In PCa cells, the methylation rate of CGIs in the promoter region of NDRG1 was higher than that in normal prostate cells. 5-Aza-CdR, a methylation inhibitor, was able to effectively reverse the aberrant methylation of NDRG1, enhancing its expression, inhibiting cell growth. NDRG1 can inhibit the cell proliferation and invasion of PCa, but its expression level is low. The aberrant methylation of NDRG1 promoter is an important mechanism for gene silencing, playing an important role in tumor occurrence and progression. Therefore, reversing the aberrant methylation of NDRG1 may be used for PCa treatment.

Conceptual models for the initiation of hepatitis B virus-associated hepatocellular carcinoma

Although chronic hepatitis B virus (HBV) infection is a known risk factor for the development of hepatocellular carcinoma (HCC), the steps involved in the progression from normal liver to HCC are poorly understood. In this review, we apply five conceptual models, previously proposed by Vineis et al. to explain carcinogenesis in general, to explore the possible steps involved in the initiation and evolution of HBV-associated HCC. Available data suggest that the most suitable and inclusive model is based on evolution of hepatocyte subpopulations. In this evolutionary model, HCC-associated changes are driven by selection and subsequent clonal expansion of phenotypically altered hepatocyte subpopulations in the microenvironment of the HBV-infected liver. This model can incorporate the wide range of mechanisms proposed to play a role in the initiation of HCC including oncogenic HBV proteins, integration of HBV DNA and chronic inflammation of the liver. The model may assist in the early prevention, detection and treatment of HCC and may guide future studies of the initiation of HBV-associated HCC.