DNA methylation in hepatocellular carcinoma

Mallory-Denk bodies and hepatocellular senescence: a causal relationship?

Mallory-Denk bodies (MDBs) are hepatocellular cytoplasmic inclusions, which occur in certain chronic liver diseases, such as alcohol-related (ASH) and metabolic dysfunction-associated (MASH) steatohepatitis, copper toxicosis, some drug-induced liver disorders, chronic cholangiopathies, and liver tumors. Our study focused on the expression of the senescence markers p21WAF1/cip1 and p16INK4a in hepatocytes containing MDBs in steatohepatitis, chronic cholangiopathies with fibrosis or cirrhosis, Wilson's disease, and hepatocellular carcinomas. Cytoplasm and nuclei of MDB-containing hepatocytes as well as MDB inclusions, except those associated with carcinoma cells, were strongly p16-positive, p21-positive, as well as p21-negative nuclei in MDB-containing hepatocytes which were observed whereas MDBs were p21-negative. Expression of the senescence marker p16 suggests that MDB formation reflects an adaptive response to chronic stress resembling senescence with its consequences, i.e., expression of inflammation- and fibrosis-prone secretome. Thus, senescence can be regarded as "double-edged sword" since, on the one hand, it may be an attempt of cellular defense, but, on the other, also causes further and sustained damage by inducing inflammation and fibrosis related to the senescence-associated secretory phenotype and thus progression of chronic liver disease.

HCV and HCC Tango-Deciphering the Intricate Dance of Disease: A Review Article

Hepatitis C virus (HCV) is a major cause of hepatocellular carcinoma (HCC) accounting for around one-third of all HCC cases. Prolonged inflammation in chronic hepatitis C (CHC), maintained through a variety of pro- and anti-inflammatory mediators, is one of the aspects of carcinogenesis, followed by mitochondrial dysfunction and oxidative stress. Immune response dysfunction including the innate and adaptive immunity also plays a role in the development, as well as in the recurrence of HCC after treatment. Some of the tumor suppressor genes inhibited by the HCV proteins are p53, p73, and retinoblastoma 1. Mutations in the telomerase reverse transcriptase promoter and the oncogene catenin beta 1 are two more important carcinogenic signaling pathways in HCC associated with HCV. Furthermore, in HCV-related HCC, numerous tumor suppressor and seven oncogenic genes are dysregulated by epigenetic changes. Epigenetic regulation of gene expression is considered as a lasting "epigenetic memory", suggesting that HCV-induced changes persist and are associated with liver carcinogenesis even after cure. Epigenetic changes and immune response dysfunction are recognized targets for potential therapy of HCC.

DNA methylation markers in the detection of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and has a poor prognosis. Epigenetic modification has been shown to be deregulated during HCC development by dramatically impacting the differentiation, proliferation, and function of cells. One important epigenetic modification is DNA methylation during which methyl groups are added to cytosines without changing the DNA sequence itself. Studies found that methylated DNA markers can be specific for detection of HCC. On the basis of these findings, the utility of methylated DNA markers as novel biomarkers for early-stage HCC has been measured in blood, and indeed superior sensitivity and specificity have been found in several studies when compared to current surveillance methods. However, a variety of factors currently limit the immediate application of these exciting biomarkers. In this review, we provide a detailed rationalisation of the approach and basis for the use of methylation biomarkers for HCC detection and summarise recent studies on methylated DNA markers in HCC focusing on the importance of the aetiological cause of liver disease in the mechanisms leading to cancer.

Roles of NOLC1 in cancers and viral infection

BACKGROUND

The nucleolus is considered the center of metabolic control and an important organelle for the biogenesis of ribosomal RNA (rRNA). Nucleolar and coiled-body phosphoprotein 1(NOLC1), which was originally identified as a nuclear localization signal-binding protein is a nucleolar protein responsible for nucleolus construction and rRNA synthesis, as well as chaperone shuttling between the nucleolus and cytoplasm. NOLC1 plays an important role in a variety of cellular life activities, including ribosome biosynthesis, DNA replication, transcription regulation, RNA processing, cell cycle regulation, apoptosis, and cell regeneration.

PURPOSE

In this review, we introduce the structure and function of NOLC1. Then we elaborate its upstream post-translational modification and downstream regulation. Meanwhile, we describe its role in cancer development and viral infection which provide a direction for future clinical applications.

METHODS

The relevant literatures from PubMed have been reviewed for this article.

CONCLUSION

NOLC1 plays an important role in the progression of multiple cancers and viral infection. In-depth study of NOLC1 provides a new perspective for accurate diagnosis of patients and selection of therapeutic targets.

Hazardous impacts of glyphosate on human and environment health: Occurrence and detection in food

With the ever-increasing human population, farming lands are decreasing every year, therefore, for effective crop management; agricultural scientists are continually developing new strategies. However, small plants and herbs always impart a much loss in the yields of the crop and farmers are using tons of herbicides to eradicate that problem. Across the world, several herbicides are available in the market for effective crop management, however, scientists observed various environmental and health effects of the herbicides. Over the past 40 years, the herbicide glyphosate has been used extensively with the assumption of negligible effects on the environment and human health. However, in recent years, concerns have increased globally about the potential direct and indirect effects on human health due to the excessive use of glyphosate. As well, the toxicity on ecosystems and the possible effects on all living creatures have long been at the center of a complex discrepancy about the authorization for its use. The World Health Organization also further classified glyphosate as a carcinogenic toxic component and it was banned in 2017 due to numerous life-threatening side effects on human health. In the present era, the residues of banned glyphosate are more prevalent in agricultural and environmental samples which are directly affecting human health. Various reports revealed the detailed extraction process of glyphosate from different categories of the food matrix. Therefore, in the present review, to reveal the importance of glyphosate monitoring in the food matrix, we discussed the environmental and health effects of glyphosate with acute toxicity levels. Also, the effect of glyphosate on aquatic life is discussed in detail and various detection methods such as fluorescence, chromatography, and colorimetric techniques from different food samples with a limit of detection values are revealed. Overall, this review will give an in-depth insight into the various toxicological aspects and detection of glyphosate from food matrix using various advanced analytical techniques.

Identification of Prognostic Biomarkers for Suppressing Tumorigenesis and Metastasis of Hepatocellular Carcinoma through Transcriptome Analysis

Cancer is one of the deadliest diseases developed through tumorigenesis and could be fatal if it reaches the metastatic phase. The novelty of the present investigation is to explore the prognostic biomarkers in hepatocellular carcinoma (HCC) that could develop glioblastoma multiforme (GBM) due to metastasis. The analysis was conducted using RNA-seq datasets for both HCC (PRJNA494560 and PRJNA347513) and GBM (PRJNA494560 and PRJNA414787) from Gene Expression Omnibus (GEO). This study identified 13 hub genes found to be overexpressed in both GBM and HCC. A promoter methylation study showed these genes to be hypomethylated. Validation through genetic alteration and missense mutations resulted in chromosomal instability, leading to improper chromosome segregation, causing aneuploidy. A 13-gene predictive model was obtained and validated using a KM plot. These hub genes could be prognostic biomarkers and potential therapeutic targets, inhibition of which could suppress tumorigenesis and metastasis.

Prognostic value of long non-coding RNA MALAT1 in hepatocellular carcinoma: A study based on multi-omics analysis and RT-PCR validation

Background: This study aimed to explore the relationship between MALAT1 and the prognosis of patients with hepatocellular carcinoma (HCC). Methods: We constructed a MALAT1 protein-protein interaction network using the STRING database and a network of competing endogenous RNAs (ceRNAs) using the StarBase database. Using data from the GEPIA2 database, we studied the association between genes in these networks and survival of patients with HCC. The potential mechanisms underlying the relationship between MALAT1 and HCC prognosis were studied using combined data from RNA sequencing, DNA methylation, and somatic mutation data from The Cancer Genome Atlas (TCGA) liver cancer cohort. Tumor tissues and 19 paired adjacent non-tumor tissues (PANTs) from HCC patients who underwent radical resection were analyzed for MALAT1 mRNA levels using real-time PCR, and associations of MALAT1 expression with clinicopathological features or prognosis of patients were analyzed using log-rank test and Gehan-Breslow-Wilcoxon test. Results: Five interacting proteins and five target genes of MALAT1 in the ceRNA network significantly correlated with poor survival of patients with HCC (p < 0.05). High MALAT1 expression was associated with mutations in two genes leading to poor prognosis and may upregulate some prognostic risk genes through methylation. MALAT1 was significantly co-expressed with various signatures of genes involved in HCC progression, including the cell cycle, DNA damage repair, mismatch repair, homologous recombination, molecular cancer m6A, exosome, ferroptosis, infiltration of lymphocyte (p < 0.05). The expression of MALAT1 was markedly upregulated in HCC tissues compared with PANTs. In Kaplan-Meier analysis, patients with high MALAT1 expression had significantly shorter progression-free survival (PFS) (p = 0.033) and overall survival (OS) (p = 0.023) than those with low MALAT1 expression. Median PFS was 19.2 months for patients with high MALAT1 expression and 52.8 months for patients with low expression, while the corresponding median OS was 40.5 and 78.3 months. In subgroup analysis of patients with vascular invasion, cirrhosis, and HBsAg positive or AFP positive, MALAT1 overexpression was significantly associated with shorter PFS and OS. Models for predicting PFS and OS constructed based on MALAT1 expression and clinicopathological features had moderate predictive power, with areas under the receiver operating characteristic curves of 0.661-0.731. Additionally, MALAT1 expression level was significantly associated with liver cirrhosis, vascular invasion, and tumor capsular infiltration (p < 0.05 for all). Conclusion: MALAT1 is overexpressed in HCC, and higher expression is associated with worse prognosis. MALAT1 mRNA level may serve as a prognostic marker for patients with HCC after hepatectomy.

Anticarcinogenic Effects of Isothiocyanates on Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, accounting for about 90% of cases. Sorafenib, lenvatinib, and the combination of atezolizumab and bevacizumab are considered first-line treatments for advanced HCC. However, clinical application of these drugs has also caused some adverse reactions such as hypertension, elevated aspartate aminotransferases, and proteinuria. At present, natural products and their derivatives have drawn more and more attention due to less side effects as cancer treatments. Isothiocyanates (ITCs) are one type of hydrolysis products from glucosinolates (GLSs), secondary plant metabolites found exclusively in cruciferous vegetables. Accumulating evidence from encouraging in vitro and in vivo animal models has demonstrated that ITCs have multiple biological activities, especially their potentially health-promoting activities (antibacterial, antioxidant, and anticarcinogenic effects). In this review, we aim to comprehensively summarize the chemopreventive, anticancer, and chemosensitizative effects of ITCs on HCC, and explain the underlying molecular mechanisms.

Chemokine clouding and liver cancer heterogeneity: Does it impact clinical outcomes?

Tumor heterogeneity is a predominant feature of hepatocellular carcinoma (HCC) that plays a crucial role in chemoresistance and limits the efficacy of available chemo/immunotherapy regimens. Thus, a better understanding regarding the molecular determinants of tumor heterogeneity will help in developing newer strategies for effective HCC management. Chemokines, a sub-family of cytokines are one of the key molecular determinants of tumor heterogeneity in HCC and are involved in cell survival, growth, migration, and angiogenesis. Herein, we provide a panoramic insight into the role of chemokines in HCC heterogeneity at genetic, epigenetic, metabolic, immune cell composition, and tumor microenvironment levels and its impact on clinical outcomes. Interestingly, our in-silico analysis data showed that expression of chemokine receptors impacts infiltration of various immune cell populations into the liver tumor and leads to heterogeneity. Thus, it is evident that aberrant chemokines clouding impacts HCC tumor heterogeneity and understanding this phenomenon in depth could be harnessed for the development of personalized medicine strategies in future.

Prevalence of Primary Liver Cancer is Affected by Place of Birth in Hispanic People Residing in the United States: All of Us Research Program Report

BACKGROUND

Hispanic individuals have a disproportionately higher incidence and mortality for stomach, cervix, and liver cancers compared to Non-Hispanic White people. Since disparities in cancer incidence are influenced by multiple factors including immigration, elucidating the effect of birthplace and exposure to risk factors on the prevalence of these cancers is crucial for identifying high-risk populations and target risk reduction interventions.

METHODS

The National Institutes of Health All of Us Research Program is a prospective, multidimensional biomedical data resource of underrepresented, minoritized people. The Registered Tier Dataset v5 was utilized to evaluate the prevalence and risk of stomach, cervix, and liver cancers among United States (US) born and non-US born Hispanic participants.

RESULTS

Of over 434 000 current participants, 60 540 are Hispanic; 30 803 (50.9%) reported being US born and 29 294 (48.4%) non-US born. Non-US born Hispanic participants had significantly higher prevalence (.39% vs .21%, P < .001) and associated risk (OR 1.84, 95% CI 1.29-2.64, P < .001) of liver cancer, and trend towards higher prevalence of stomach (.14% vs .09%, P = .076) and cervix cancers (.27% vs .20%, P = .083) compared to US born counterparts. US born Hispanic patients with these 3 cancers were significantly younger than non-US born cohort (mean age 56.8 vs 61.7 years, P < .001).

DISCUSSION

This is the first report using All of Us data to show that non-US born Hispanic participants have a higher risk of liver cancer compared to US born participants. Further analyses, including genomic studies, are necessary to understand these differences and identify targets for risk reduction interventions.

Relation of the methylation state of RUNX3 and p16 gene promoters with hepatocellular carcinoma in Egyptian patients

Background

Hepatocellular carcinoma (HCC) is the most common primary hepatic malignancy of adults. RUNX3 and p16 are tumor suppressor genes that may be inactivated by hypermethylation which is a key epigenetic mechanism that contributes to the initiation and progression of various types of human carcinomas including HCC. The aim of this study was to assess the association of hypermethylation of RUNX3 and p16 gene promoters with the incidence of HCC in Egyptian patients. The study included 120 subjects: 30 HCC patients, 30 patients with hepatitis C virus (HCV) without cirrhosis, 30 cirrhotic patients, and 30 healthy volunteers. Methylation-specific polymerase chain reaction (PCR) was done for detection of hypermethylated p16 and RUNX3. Serum levels of liver enzymes and albumin were detected spectrophotometrically and alpha fetoprotein (AFP) was measured in serum by ELISA.

Results

Methylation of RUNX3 and p16 was detected in 25/30 (83.3%) and 26/30 (86.7%) of HCC patients, respectively. The methylation state of both RUNX3 and p16 genes was significantly higher in HCC patients compared to the control subjects (P = 0.016, OR = 4.38) and (P = 0.014, OR = 4.97), respectively. The methylation of both promoters was associated with higher AFP levels in the serum of all patients.

Conclusions

Hypermethylation of RUNX3 and p16 is significantly associated with the development of HCC and may be implicated in its pathogenesis.

Epigenetic Changes Affecting the Development of Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma is a life-threatening disease. Despite many efforts to understand the exact pathogenesis and the signaling pathways involved in its formation, treatment remains unsatisfactory. Currently, an important function in the development of neoplastic diseases and treatment effects is attributed to changes taking place at the epigenetic level. Epigenetic studies revealed modified methylation patterns in HCC, dysfunction of enzymes engaged in the DNA methylation process, the aberrant function of non-coding RNAs, and a set of histone modifications that influence gene expression. The aim of this review is to summarize the current knowledge on the role of epigenetics in the formation of hepatocellular carcinoma.

Abstract

Hepatocellular carcinoma (HCC) remains a serious oncologic issue with still a dismal prognosis. So far, no key molecular mechanism that underlies its pathogenesis has been identified. Recently, by specific molecular approaches, many genetic and epigenetic changes arising during HCC pathogenesis were detected. Epigenetic studies revealed modified methylation patterns in HCC tumors, dysfunction of enzymes engaged in the DNA methylation process, and a set of histone modifications that influence gene expression. HCC cells are also influenced by the disrupted function of non-coding RNAs, such as micro RNAs and long non-coding RNAs. Moreover, a role of liver cancer stem cells in HCC development is becoming evident. The reversibility of epigenetic changes offers the possibility of influencing them and regulating their undesirable effects. All these data can be used not only to identify new therapeutic targets but also to predict treatment response. This review focuses on epigenetic changes in hepatocellular carcinoma and their possible implications in HCC therapy.

Screening the genome for HCC-specific CpG methylation signatures as biomarkers for diagnosis and prognosis evaluation

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common and invasive malignant tumors in the world. The change in DNA methylation is a key event in HCC.

METHODS

Methylation datasets for HCC and 17 other types of cancer were downloaded from The Cancer Genome Atlas (TCGA). The CpG sites with large differences in methylation between tumor tissues and paracancerous tissues were identified. We used the HCC methylation dataset downloaded from the TCGA as the training set and removed the overlapping sites among all cancer datasets to ensure that only CpG sites specific to HCC remained. Logistic regression analysis was performed to select specific biomarkers that can be used to diagnose HCC, and two datasets-GSE157341 and GSE54503-downloaded from GEO as validation sets were used to validate our model. We also used a Cox regression model to select CpG sites related to patient prognosis.

RESULTS

We identified 6 HCC-specific methylated CpG sites as biomarkers for HCC diagnosis. In the training set, the area under the receiver operating characteristic (ROC) curve (AUC) for the model containing all these sites was 0.971. The AUCs were 0.8802 and 0.9711 for the two validation sets from the GEO database. In addition, 3 other CpG sites were analyzed and used to create a risk scoring model for patient prognosis and survival prediction.

CONCLUSIONS

Through the analysis of HCC methylation datasets from the TCGA and Gene Expression Omnibus (GEO) databases, potential biomarkers for HCC diagnosis and prognosis evaluation were ascertained.

DNA methylation in oral squamous cell carcinoma: from its role in carcinogenesis to potential inhibitor drugs

DNA methylation is one of epigenetic changes most frequently studied nowadays, together with its relationship with oral carcinogenesis. A group of enzymes is responsible for methylation process, known as DNA methyltransferases (DNMT). Although essential during embryogenesis, DNA methylation pattern alterations, including global hypomethylation or gene promoter hypermethylation, can be respectively associated with chromosomal instability and tumor suppressor gene silencing. Higher expression of DNA methyltransferases is a common finding in oral cancer and may contribute to inactivation of important tumor suppressor genes, influencing development, progression, metastasis, and prognosis of the tumor. To control these alterations, inhibitor drugs have been developed as a way to regulate DNMT overexpression, and they are intended to be associated with ongoing chemo- and radiotherapy in oral cancer treatments. In this article, we aimed to highlight the current knowledge about DNA methylation in oral cancer, including main hyper/hypomethylated genes, DNMT expression and its inhibitor treatments.

Using Integrated Bioinformatics Analysis to Identify Abnormally Methylated Differentially Expressed Genes in Hepatocellular Carcinoma

Objective

For the identification of abnormally methylated differentially expressed genes (MDEGs) in hepatocellular carcinoma (HCC), this study integrated four microarray datasets to investigate the fundamental mechanisms of tumorigenesis.

Methods

We obtained the expression (GSE76427, GSE57957) and methylation (GSE89852, GSE54503) profiles from Gene Expression Omnibus (GEO). The abnormally MDEGs were identified by using R software. We used the clusterProfiler package for the functional and pathway enrichment analysis. The String database was used to build the protein–protein interaction (PPI) network and visualize it in Cytoscape. MCODE was employed in the module analysis. Additionally, Gene Expression Profiling Interactive Analysis (GEPIA) and The Cancer Genome Atlas (TCGA) were employed to validate results. Lastly, we used cBioPortal software to examine the hub genetic alterations.

Results

We identified 162 hypermethylated, down-regulated genes and 190 hypomethylated, up-regulated genes. Up-regulated genes with low methylation were enriched in biological processes, such as keratinocyte proliferation, and calcium homeostasis. Pathway analysis was enriched in the AMPK and PI3K-Akt signaling pathways. The PPI network identified PTK2, VWF, and ITGA2 as hypomethylated, high-expressing hub genes. Down-regulated genes with high methylation were related to responses to peptide hormones and estradiol, multi-multicellular organism process. Pathway analysis indicated enrichment in camp, oxytocin signaling pathways. The PPI network identified CFTR, ESR1, and CXCL12 as hypermethylated, low-expressing hub genes. Upon verification in TCGA databases, we found that the expression and methylation statuses of the hub genes changed significantly, and it was consistent with our results.

Conclusion

The novel abnormally MDEGs and pathways in HCC were identified. These results helped us further understand the molecular mechanisms underlying HCC invasion, metastasis, and development. Hub genes can serve as biomarkers for an accurate diagnosis and treatment of HCC, and PTK2, VWF, ITGA2, CFTR, ESR1, and CXCL12 are included.

Epigenetic identification of mitogen-activated protein kinase 10 as a functional tumor suppressor and clinical significance for hepatocellular carcinoma

Background

Mitogen-activated protein kinase 10 (Mapk10) is a member of the c-jun N-terminal kinases (jnk) subgroup in the MAPK superfamily, and was proposed as a tumor suppressor inactivated epigenetically. Its role in hepatocellular carcinoma (HCC) has not yet been illustrated. We aimed to investigate the expression and epigenetic regulation of mapk10 as well as its clinical significance in HCC.

Results

Mapk10 was expressed in almost all the normal tissues including liver, while we found that the protein expression of MAPK10 was significantly downregulated in clinical samples of HCC patients compared with these levels in adjacent normal tissues (29/46, P < 0.0001). Clinical significance of MAPK10 expression was then assessed in a cohort of 59 HCC cases, which indicated its negative expression was significantly correlated with advanced tumor stage (P = 0.001), more microsatellite nodules (P = 0.025), higher serum AFP (P = 0.001) and shorter overall survival time of HCC patients. Methylation was further detected in 58% of the HCC cell lines we tested and in 66% of primary HCC tissues by methylation-specific PCR (MSP), which was proved to be correlated with the silenced or downregulated expression of mapk10. To get the mechanisms more clear, the transcriptional silencing of mapk10 was reversed by pharmacological demethylation, and ectopic expression of mapk10 in silenced HCC cell lines significantly inhibited the colony formation ability, induced apoptosis, or enhanced the chemosensitivity of HCC cells to 5-fluorouracil.

Conclusion

Mapk10 appears to be a functional tumor suppressor gene frequently methylated in HCC, which could be a valuable biomarker or a new diagnosis and therapy target in a clinical setting.

Exploring DNA Methylation Profiles Altered in Cryptogenic Hepatocellular Carcinomas by High-Throughput Targeted DNA Methylation Sequencing: A Preliminary Study for Cryptogenic Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) includes cryptogenic hepatocellular carcinomas (CR-HCC) that lack a defined cause. Specific DNA methylation patterns and comparisons of the aberrant alterations in DNA methylation between CR-HCC and adjacent peritumor tissues (APTs) have not yet been reported.

Methods

The SureSelectXT Methyl-Seq Target Enrichment System was used to sequence targeted DNA methylation in three paired CR-HCC tissues and APTs. Gene Ontology (GO) enrichment and KEGG pathway analysis were performed to investigate the DNA methylation mechanism of CR-HCC. The mRNA expression levels of HOXB-AS3, HOXB6, HOXB3, USP18, MAP3K6, TIRAP, TNNI2, SHC3, CTTN, and TFAP2A, selected from the identified signaling pathways, were evaluated by quantitative real-time PCR (qPCR).

Results

A total of 1728 differentially methylated regions (DMRs) were identified in tumor tissues compared with non-tumor tissues, of which 868 DMRs were hypermethylated and 860 were hypomethylated. The DMRs were mapped within 2091 DMR-associated genes (DMGs). The mRNA expression of HOXB-AS3, HOXB3, and MAP3K6 was downregulated in CR-HCC tissues compared to the APTs. However, the mRNA expression of TIRAP, SHC3, and CTTN was upregulated in the CR-HCC tissues. Differences between the mRNA expression of HOXB6, USP18, TNNI2, and TFAP2A in the CR-HCC and APTS tissues were not statistically significant. GO analysis showed that the molecular functions of “binding”, “protein binding”, and “cytoskeletal protein binding” were the main categories for the hypermethylated DMGs. The hypomethylated DMGs were mostly enriched in the molecular functions “binding”, “protein binding”, “calcium ion binding”, among others. KEGG pathway analysis showed that the hypermethylated DMGs were enriched in several pathways such as “estrogen signaling pathway”, while hypomethylated DMGs were enriched in several pathways such as “proteoglycans in cancer”, suggesting that epigenetic modifications play important roles in the cryptogenic hepatocarcinogenesis.

Conclusion

These results provide useful information for future work to characterize the functions of epigenetic mechanisms on CR-HCC.

Transcriptome-Wide 5-Methylcytosine Functional Profiling of Long Non-Coding RNA in Hepatocellular Carcinoma

Background

Growing evidence indicates that methylation status is associated with the pathogenesis of numerous types of cancers. Among these, hepatocellular carcinoma (HCC) is a deadly disease threatening global human health. Although 5-methylcytosine (m5C) has been identified as an important regulatory modification, its distribution in solid tumors, including HCC, remains unclear. The present study aimed to explore the distribution of m5C in HCC.

Materials and Methods

Six pairs of human HCC tissues and adjacent non-tumor tissues were collected to analyze the transcriptome-wide m5C methylation of long non-coding RNA (lncRNA). RNA MeRIP-seq was performed to identify m5C peaks on lncRNA and differences in m5C distribution between HCC and adjacent tissues. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment pathway analyses were explored to predict the possible roles of m5C.

Results

Using m5C peak sequencing, we observed that a sequence motif was necessary for m5C methylation in HCC lncRNA. Unsupervised hierarchical cluster analysis confirmed that lncRNA m5C methylation occurred more frequently in HCC than adjacent non-tumor tissues. RNA sequencing data demonstrated that more genes were up-regulated by methylation in HCC, while methylation down-regulated more genes in adjacent non-tumor tissues. GO and KEGG pathway analyses revealed that genes having a significant correlation with m5C sites in lncRNA were involved in HCC signaling pathways.

Conclusion

Our results revealed the substantially different amounts and distributions of m5C in HCC compared to adjacent non-tumor tissue. We further predicted the cellular functions in HCC that m5C may participate in to provide evidence implicating m5C lncRNA epigenetic regulation in the tumorigenesis and progression in HCC.

Investigation of the Effect of 5-Aza-2'-Deoxycytidine on p15INK4, p16INK4, p18INK4, and p19INK4 Genes Expression, Cell Growth Inhibition, and Apoptosis Induction in Hepatocellular Carcinoma PLC/PRF/5 Cell Line

Background

Cyclin-dependent kinases (CDKs) are the key regulators of cell-cycle transitions and characterized by needing a separate subunit, a cyclin, which provides domains essential for enzymatic activity. The activities of cyclin-CDK complexes are controlled by a group of molecules that inhibit CDK activity and CDK inhibitors (CKIs). Cancer often exhibits an aberrant CpG methylation of promoter regions of tumor suppressor genes such as CKIs. Treatment with the DNA demethylating agents, such as 5-aza-2'-deoxycytidine (5-Aza-CdR), can restore and upregulate CKIs. Previously, we reported the effect of 5-Aza-CdR and genistein on DNA methyltransferase (DNMTs) in hepatocellular carcinoma (HCC). The aim of the present study was to evaluate the effect of 5-Aza-CdR on p15INK4, p16INK4, p18INK4, and p19INK4 genes expression, cell growth inhibition, and apoptosis induction in HCC PLC/PRF/5 cell line.

Materials and Methods

The effect of 5-Aza-CdR on the cell growth of PLC/PRF/5 cells, genes expression, and apoptosis induction were assessed by 3-[4, 5-dimethyl-2-thiazolyl]-2, 5-diphenyl-2H-tetrazolium bromide assay, real-time quantitative reverse transcription-polymerase chain reaction analysis, and flow cytometry, respectively.

Results

5-Aza-CdR (0, 1, 5, 10, 25, and 50 μM) inhibited PLC/PRF/5 cell growth at different periods significantly. This compound induced apoptosis and reactivated p15INK4, p16INK4, p18INK4, and p19INK4 genes expression at a concentration of 5 μM significantly.

Conclusion

5-Aza-CdR can inhibit cell viability and induce apoptosis by epigenetic reactivation of p15INK4, p16INK4, p18INK4, and p19INK4 genes in HCC PLC/PRF/5.

Association of RASSF1A hypermethylation with risk of HBV/HCV-induced hepatocellular carcinoma: A meta-analysis

BACKGROUND

Researchers have discovered a large number of DNA methylation patterns in human cancer. These cancer-specific methylation patterns can provide information for the diagnosis, treatment, and prognosis of cancer. Methylation studies can find new biomarkers based on epigenetic analysis and apply these biomarkers to clinical oncology. Many studies on the association between RAASF1A methylation status and susceptibility to hepatitis B virus (HBV)/hepatitis C virus (HCV)-induced hepatocellular carcinoma (HCC) have reached controversial conclusions. Hence, the current review comprehensively assessed the correlation between Ras association domain family 1A (RASSF1A) methylation and the risk of the HCV/HBV-induced HCC.

METHODS

The appropriated publications were extracted in EMBASE, PubMed, Web of Science, Cochrane Library, and China National Knowledge Infrastructure databases using STATA 5.0 software. The odds ratios (ORs) with 95 % confidence interval (95 % CI) of RASSF1A methylation were computed.

RESULTS

A total of 1015 HBV/HCV-related HCC samples, 124 non-HBV/HCV-related HCC (NBNC-HCC) samples, and 1225 nontumorous controls were extracted and examined in this research. The frequency of the methylated RASSF1A in the HBV/HCV-related tumor cases displayed a significantly increased OR compared with the overall nontumor samples (OR = 19.372, 95 % CI = 11.060-33.931, P = 0.000). The frequency of the methylated RASSF1A in HBV/HCV-related neoplasm cases displayed a significantly increased OR compared with the non-HBV/HCV-related neoplasm (NBNC-neoplasm) samples (OR = 2.150, 95 % CI = 1.398-3.308, P = 0.000). Compared with normal, chronic hepatitis B or C, cirrhosis, and paracancerous samples, the pooled OR of the RASSF1A promoter methylation in the HBV/HCV-induced HCC samples was 62.785(95 % CI = 35.224-111.909), 25.07 (95 % CI = 13.85-45.36), 6.89 (95 % CI = 3.33-14.264) and 9.02 (95 % CI = 0.91-89.80), respectively. The rate of RASSF1A hypermethylation was robustly correlated with tumor size and vascular invasion, and the pooled OR was 0.346 (95 % CI = 0.210 - 0.569) and 0.081 (95 % CI = 0.022 - 0.303), respectively.

CONCLUSION

Results showed robust associations between RASSF1A gene methylation in promoter region and enhanced HBV/HCV-related HCC susceptibility, thereby revealing that RASSF1A methylation status may serve as an important indicator for HCC oncogenesis.

Differential hypermethylation of the VTRNA2-1 promoter in hepatocellular carcinoma as a prognostic factor: Tumor marker prognostic study

BACKGROUND

Vault RNA 2-1 (VTRNA2-1, also called nc886) is a 108-nucleotide noncoding transcript that is epigenetically controlled via 18 CpG dinucleotide modifications of its promoter, and can exert either tumor suppressor or oncogenic functions depending on cell types of cancers. In hepatocellular carcinoma (HCC), the role of VTRNA2-1 in prognosis of patients remains unexplored. Here, we analysed the methylation status of the VTRNA2-1 promoter and its correlation with clinical parameters in patients with HCC.

PATIENTS AND METHODS

A total of 92 patients with HCC were enrolled, genomic DNA of tumor versus normal tissues were extracted and bisulfite modified. VTRNA2-1 promoter regions chr5: 135416381 (cg06536614), 135416388, 135416394 (cg26328633), and 135416398 (cg25340688) were PCR amplified and pyrosequenced. The methylation status of VTRNA2-1 in patients was further analysed with other clinical parameters via univariate and multivariate analysis.

RESULTS

The differential hypermethylation status (tumor- normal) of the VTRNA2-1 promoter in HCC correlated well with the presence of large tumor size (p = 0.001), pathological vascular invasion (p = 0.036), tumor recurrence (p = 0.007) and more advanced tumor stage (stage III AJCC) in patients (p = 0.03). In addition, the methylation of the VTRNA2-1 promoter increased in stage III HCC tumor compared with stage I & II tumor (64.7% versus 36.0%, p = 0.030). Furthermore, the differential hypermethylation status of the VTRNA2-1 promoter was an independent factor for patient outcome after partial hepatectomy using multivariate Cox regression analysis (p = 0.011, HR = 2.305). Using another public dataset (GSE89852), we found that the differential hypermethylation of the VTRNA2-1 promoter was also significantly associated with tumor recurrence.

CONCLUSIONS

Patients had unfavourable outcomes when the VTRNA2-1 promoter was differentially hypermethylated in tumor tissues compared to its adjacent normal tissues. These findings suggest that such patients should receive intensive follow-up care or possible adjuvant therapy after liver resection.

Integrative analysis of DNA methylation and gene expression reveals distinct hepatocellular carcinoma subtypes with therapeutic implications

We aimed to develop an HCC classification model based on the integrated gene expression and methylation data of methylation-driven genes. Genome, methylome, transcriptome, proteomics and clinical data of 369 HCC patients from The Cancer Genome Atlas Network were retrieved and analyzed. Consensus clustering of the integrated gene expression and methylation data from methylation-driven genes identified 4 HCC subclasses with significant prognosis difference. HS1 was well differentiated with a favorable prognosis. HS2 had high serum α-fetoprotein level that was correlated with its poor outcome. High percentage of CTNNB1 mutations corresponded with its activation in WNT signaling pathway. HS3 was well differentiated with low serum α-fetoprotein level and enriched in metabolism signatures, but was barely involved in immune signatures. HS3 also had high percentage of CTNNB1 mutations and therefore enriched in WNT activation signature. HS4 was poorly differentiated with the worst prognosis and enriched in immune-related signatures, but was barely involved in metabolism signatures. Subsequently, a prediction model was developed. The prediction model had high sensitivity and specificity in distributing potential HCC samples into groups identical with the training cohort. In conclusion, this work sheds light on HCC patient prognostication and prediction of response to targeted therapy.

Classification or non-classification of substances with positive tumor findings in animal studies: Guidance by the German MAK commission

One of the important tasks of the German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (known as the MAK Commission) is in the evaluation of a potential for carcinogenicity of hazardous substances at the workplace. Often, this evaluation is critically based on data on carcinogenic responses seen in animal studies and, if positive tumor responses have been observed, this will mostly lead to a classification of the substance under investigation into one of the classes for carcinogens. However, there are cases where it can be demonstrated with a very high degree of confidence that the tumor findings in the experimental animals are not relevant for humans at the workplace and, therefore, the MAK Commission will not classify the respective substance into one of the classes for carcinogens. This paper will summarize the general criteria used by the MAK Commission for the categorization into "carcinogen" and "non-carcinogen" and compare this procedure with those used by other national and international organizations.

Diagnostic value of NKG2D promoter methylation in hepatitis B virus-associated hepatocellular carcinoma

Aim: Natural killer cell receptor group 2D (NKG2D) plays an important role in the immune regulation of tumors. We speculate that DNA methylation are involved in the regulation of NKG2D gene. Methods: We investigated the methylation status of the NKG2D promoter in peripheral blood mononuclear cells of hepatocellular carcinoma (HCC) patients, chronic hepatitis B patients and healthy controls by methylation-specific PCR and the mRNA expression level was examined by real-time quantitative PCR. Results: The methylation frequency of NKG2D promoter in HCC patients was higher than that of chronic hepatitis B patients and healthy controls. NKG2D promoter methylation has a good predictive value for HCC diagnosis. Conclusion: NKG2D promoter methylation can be used as a noninvasive marker for detecting HCC.

Dysregulation of Nrf2 in Hepatocellular Carcinoma: Role in Cancer Progression and Chemoresistance

The liver executes versatile functions and is the chief organ for metabolism of toxicants/xenobiotics. Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and the third foremost cause of cancer death worldwide. Oxidative stress is a key factor related with the development and progression of HCC. Nuclear factor erythroid 2 [NF-E2]-related factor 2 (Nrf2) is a cytosolic transcription factor, which regulates redox homeostasis by activating the expression of an array of antioxidant response element-dependent genes. Nrf2 displays conflicting roles in normal, healthy liver and HCC; in the former, Nrf2 offers beneficial effects, whereas in the latter it causes detrimental effects favouring the proliferation and survival of HCC. Sustained Nrf2 activation has been observed in HCC and facilitates its progression and aggressiveness. This review summarizes the role and mechanism(s) of action of Nrf2 dysregulation in HCC and therapeutic options that can be employed to modulate this transcription factor.

Studying the frequency of aberrant DNA methylation of APC, P14, and E-cadherin genes in HCV-related hepatocarcinogenesis

BACKGROUND

Data about the molecular pathogenesis of hepatitis C-related hepatocellular carcinoma (HCC) are still challenging.

OBJECTIVES

Therefore, we tried to investigate the epigenetic study of three nominated genes (APC, P14, and E-cadherin) in the pathogenesis of HCV-related HCC in Egyptian.

METHODS

Between March 2016 and March 2017, the DNA methylation, and quantification using (epigenetic ELISA kit) for E-cadherin, APC, and P14 genes were studied in three groups of patients: HCV related liver cirrhosis without HCC group (LC-group; n= 20), HCC on top of HCV-related cirrhosis (HCC-group; n= 20), and a third apparently healthy control group (control-group; n= 10).

RESULTS

E-cad methylation showed non-significant differences between groups. P14 methylation was occurred only in HCC-group (45%). APC methylation was the highest in HCC group (70%). Methylation level was high in HCC group in comparison to both LC and control groups (P< 0.001). DNA methylation at a cutoff point > 2.9 ng/ml predicts HCC in LC-group with 90% sensitivity and 80% specificity and at level > 2.3 ng/ml had 95% sensitivity and 90% specificity in control-group. The pooled sensitivity, specificity, positive and negative predictive values and accuracy were 90%, 60%, 69.2, 85.7 and 75% respectively.

CONCLUSION

Aberrant DNA methylation of multiple genes is associated with disease progression in HCV related cirrhosis. Moreover, early detection of promotor methylation of these may sever as good biomarker for early detection and therapeutic targets in high risk patients.

Liver-enriched Genes are Associated with the Prognosis of Patients with Hepatocellular Carcinoma

Tissue-enriched genes are highly expressed in one particular tissue type and represent distinct physiological processes. The dynamic profile of tissue-enriched genes during tumorigenesis and progression remains largely unstudied. Here, we identified tissue-enriched genes from 12 tissue types based on RNA sequencing data from the Cancer Genome Atlas (TCGA), and found that the liver had the largest number of such genes among the 12 tissue types. The characteristics of liver-enriched genes were further investigated. Most liver-enriched genes were downregulated and metabolism-related genes, which were associated with pathological stage and dedifferentiation in patients with hepatocellular carcinoma (HCC). Hypermethylation might be a mechanism underlying the downregulation of liver-enriched genes. We constructed a liver-enriched gene set and demonstrated that it is associated with the prognosis of the patients with HCC both in the TCGA cohort and the Gene Expression Omnibus (GEO) datasets. Moreover, we discovered that the degree of the dissimilarity between tumors and normal tissues was correlated with the prognosis of patients with HCC and the biological behaviours of the tumors. These results will help identify prognostic biomarkers of patients with HCC, and enhance our understanding of the molecular mechanisms of hepatocarcinogenesis and progression.

Hypermethylation of NF-κB-Activating Protein-Like (NKAPL) Promoter in Hepatocellular Carcinoma Suppresses Its Expression and Predicts a Poor Prognosis

BACKGROUND AND AIM

Hepatocellular carcinoma (HCC) is a complicated disease with low survival rate partially due to frequent recurrence and no efficient therapy. Promoter hypermethylation of tumor suppressor genes has been demonstrated as one of the molecular mechanisms contributing to tumorigenesis and progression in HCC. This study aims to investigate regulation of NKAPL expression by promoter methylation and its clinical relevance as a biomarker for HCC.

METHODS

We measured mRNA expression of NKAPL in 5 HCC cell lines and a cohort of 62 pairs of primary HCC tumor and their adjacent non-cancer liver tissues. NKAPL protein expression on HCC cell lines and clinical samples was assessed by Western blot and immunohistochemistry, respectively. Association analyses between NKAPL expression and clinicopathologic characteristics in the cohort were conducted. Methylation statuses of NKAPL promoter in 18 pairs of tumor and adjacent non-tumor HCC samples were studied using methylation-specific PCR. Biological functions of NKAPL in HCC were investigated by ectopic expression of NKAPL in HCC cells, and cell viability and cell cycle analyses were performed.

RESULTS

Our present study showed suppressed expression and promoter hypermethylation are common events in HCC. Demethylation experiment in HCC cells demonstrated that the NKAPL expression was regulated by promoter methylation. In addition, high methylation level of NKAPL and its low expression predict poor outcome. Furthermore, ectopic expression of NKAPL in the HCC cells inhibited cell growth.

CONCLUSIONS

Our findings suggest that methylation of NKAPL is a frequent event and is a potential prognosis biomarker in HCC.

Di-N-octylphthalate acts as a proliferative agent in murine cell hepatocytes by regulating the levels of TGF-β and pro-apoptotic proteins

Di-n-octylphthalate (DNOP) is a phthalate used in the manufacturing of a wide variety of polyvinyl chloride-containing medical and consumer products. A study on chronic exposure to DNOP in rodents showed the development of pre-neoplastic hepatic lesions following exposure to a tumor initiator. The objective of this study was to identify the mechanisms by which DNOP leads to pre-neoplastic hepatic lesions. Mouse hepatocyte AML-12 and FL83B cells were treated with DNOP. The rate of cell proliferation was increased in treated cells in a concentration-dependent manner. DNOP increased the expression of transforming growth factor-β (tgf-β) in both cell lines, and primary culture mouse hepatocytes. The TGF-β receptor inhibitor LY2109761 impaired the effect of DNOP. The presence of pro-apoptotic proteins decreased in the presence of DNOP. Our observation indicates that DNOP, through an increase in the expression of tgf-β and a decrease in the levels of pro-apoptotic proteins, acts as a proliferative agent in normal mouse hepatocytes. We also studied the morphological and functional changes of the mouse liver upon a short-term treatment of DNOP. Mice exposed to DNOP displayed an epithelial-to-mesenchymal transition and cholestasis, which was reflected in an increase in hepatic bile acids and glutathione levels.

The biology of Hepatocellular carcinoma: implications for genomic and immune therapies

Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, is a leading cause of cancer-related death worldwide. It is highly refractory to most systemic therapies. Recently, significant progress has been made in uncovering genomic alterations in HCC, including potentially targetable aberrations. The most common molecular anomalies in this malignancy are mutations in the TERT promoter, TP53, CTNNB1, AXIN1, ARID1A, CDKN2A and CCND1 genes. PTEN loss at the protein level is also frequent. Genomic portfolios stratify by risk factors as follows: (i) CTNNB1 with alcoholic cirrhosis; and (ii) TP53 with hepatitis B virus-induced cirrhosis. Activating mutations in CTNNB1 and inactivating mutations in AXIN1 both activate WNT signaling. Alterations in this pathway, as well as in TP53 and the cell cycle machinery, and in the PI3K/Akt/mTor axis (the latter activated in the presence of PTEN loss), as well as aberrant angiogenesis and epigenetic anomalies, appear to be major events in HCC. Many of these abnormalities may be pharmacologically tractable. Immunotherapy with checkpoint inhibitors is also emerging as an important treatment option. Indeed, 82% of patients express PD-L1 (immunohistochemistry) and response rates to anti-PD-1 treatment are about 19%, and include about 5% complete remissions as well as durable benefit in some patients. Biomarker-matched trials are still limited in this disease, and many of the genomic alterations in HCC remain challenging to target. Future studies may require combination regimens that include both immunotherapies and molecularly matched targeted treatments.

Diagnostic Value of the Methylation of Multiple Gene Promoters in Serum in Hepatitis B Virus-Related Hepatocellular Carcinoma

This study sought to evaluate the diagnostic value of the methylation of multiple gene promoters in serum in hepatitis B virus- (HBV-) related hepatocellular carcinoma (HCC). A total of 343 participants were enrolled, including 98 patients with HCC, 75 patients with liver cirrhosis (LC), 90 patients with chronic hepatitis B (CHB), and 80 healthy individuals. RASSF1A, APC, BVES, TIMP3, GSTP1, and HOXA9 were selected as the candidate genes. The MethyLight method was used to assay promoter methylation statuses. The diagnostic performances of markers were assessed by constructing receiver operating characteristic (ROC) curves. The prevalences of methylation for RASSF1A, APC, BVES, HOXA9, GSTP1, and TIMP3 were 52.04%, 36.73%, 29.59%, 20.41%, 17.35%, and 11.22%, respectively. APC methylation completely overlapped with RASSF1A methylation. The area under the curve (AUC) for RASSF1A methylation (0.718) was better than the corresponding AUC for AFP (0.609) in distinguishing HCC from CHB. When RASSF1A, BVES, HOXA9, and AFP were combined, the AUC was 0.852 (95% CI = 0.796–0.908, P = 0.028), and the sensitivity and specificity were 83.7% and 78.9%, respectively. In conclusion, an assay that combines methylation of the RASSF1A, BVES, and HOXA9 gene promoters in serum and AFP could significantly improve HBV-related HCC diagnoses.

Comprehensive circular RNA profiling reveals the regulatory role of the circRNA-100338/miR-141-3p pathway in hepatitis B-related hepatocellular carcinoma

Circular RNAs (circRNAs) represent a class of endogenous noncoding RNAs that have recently been recognized as important regulators of gene expression and pathological networks. However, their transcriptional activities and functional mechanisms in cancer remain largely unknown. Here, we present results from a global circRNA expression and functional analysis of patients with hepatocellular carcinoma (HCC). Using a circRNA microarray, we identified 226 differentially expressed circRNAs, of which 189 were significantly upregulated and 37 were downregulated. High expression of circRNA_100338, one of the upregulated circRNAs in HCC, is closely correlated with a low cumulative survival rate and metastatic progression in HCC patients with hepatitis B. Furthermore, our in silico and experimental analyses identified miR-141-3p as a direct target of circRNA_100338. Thus, circRNA_100338 functions as an endogenous sponge for miR-141-3p in HCC. In addition, we identified the crucial antagonistic roles of circRNA_100338 and miR-141-3p in the regulation of invasive potential in liver cancer cells. Overall, the differential expression of multiple circRNAs in HCC tissues and their clinical significance in hepatitis B-related HCC patients as revealed by our study suggests that circRNA_100338 is a potentially valuable biomarker for HCC diagnosis and target for HCC therapeutics.

Virus-host interplay in hepatitis B virus infection and epigenetic treatment strategies

Worldwide, chronic hepatitis B virus (HBV) infection is a major health problem and no cure exists. Importantly, hepatocyte intrusion by HBV particles results in a complex deregulation of both viral and host cellular genetic and epigenetic processes. Among the attempts to develop novel therapeutic approaches against HBV infection, several options targeting the epigenomic regulation of HBV replication are gaining attention. These include the experimental treatment with 'epidrugs'. Moreover, as a targeted approach, the principle of 'epigenetic editing' recently is being exploited to control viral replication. Silencing of HBV by specific rewriting of epigenetic marks might diminish viral replication, viremia, and infectivity, eventually controlling the disease and its complications. Additionally, epigenetic editing can be used as an experimental tool to increase our limited understanding regarding the role of epigenetic modifications in viral infections. Aiming for permanent epigenetic reprogramming of the viral genome without unspecific side effects, this breakthrough may pave the roads for an ambitious technological pursuit: to start designing a curative approach utilizing manipulative molecular therapies for viral infections in vivo.

A New Approach to Evaluating Aberrant DNA Methylation Profiles in Hepatocellular Carcinoma as Potential Biomarkers

Hypermethylation of CpG islands in the promoter region of tumor suppressor genes (TSGs) and their subsequent silencing is thought to be one of the main mechanisms of carcinogenesis. MBD2b enrichment coupled with a NimbleGen array was applied to examine the genome-wide CpG island methylation profile of hepatocellular carcinoma (HCC). Hypermethylated DNA of 58 pairs of HCC and adjacent tissue samples was enriched and hybridized in the same array. Aberrant hypermethylated peaks of HCC and adjacent tissues were screened and annotated after data processing using NimbleScan2.5 and our newly developed Weighting and Scoring (WAS) method, respectively. Validation using bisulfite sequencing of randomly selected ANKRD45, APC, CDX1, HOXD3, PTGER and TUBB6 genes demonstrated significant hypermethylation modification in HCC samples, consistent with the array data.

Animal models as a tool in hepatocellular carcinoma research: A Review

Cancer is the first cause of death in developed countries and the second in developing countries. Concerning the most frequent worldwide-diagnosed cancer, primary liver cancer represents approximately 4% of all new cancer cases diagnosed globally. However, among primary liver cancer, hepatocellular carcinoma is by far the most common histological subtype. Notwithstanding the health promotion and disease prevention campaigns, more than half a million new hepatocellular carcinoma cases are reported yearly, being estimated to growth continuously until 2020. Taking this scenario under consideration and the fact that some aspects concerning hepatocellular carcinoma evolution and metastasize process are still unknown, animal models assume a crucial role to understand this disease. The animal models have also provided the opportunity to screen new therapeutic strategies. The present review was supported on research and review papers aiming the complexity and often neglected chemically induced animal models in hepatocarcinogenesis research. Despite the ongoing debate, chemically induced animal models, namely, mice and rat, can provide unique valuable information on the biotransformation mechanisms against xenobiotics and apprehend the deleterious effects on DNA and cell proteins leading to carcinogenic development. In addition, taking under consideration that no model achieves all hepatocellular carcinoma research purposes, criteria to define the " ideal" animal model, depending on the researchers' approach, are also discussed in this review.

Meta-analysis of possible role of cadherin gene methylation in evolution and prognosis of hepatocellular carcinoma with a PRISMA guideline

BACKGROUND

Cadherins (CDHs) have been reported to be associated with cancer. However, the clinical significance of CDH gene methylation in hepatocellular carcinoma (HCC) remains unclear.

METHODS

Based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement criteria, available studies were identified from online electronic database. The overall odds ratio (OR) and the corresponding 95% confidence interval (95% CI) were calculated and analyzed.

RESULTS

A total of 29 eligible studies with 2562 HCC samples and 1685 controls were included. E-cadherin (CDH1) hypermethylation was observed to be significantly higher in HCC than in benign, adjacent, or normal samples. Moreover, CDH1 hypermethylation was not associated with gender, tumor grade, clinical stage, hepatitis B virus (HBV), or hepatitis C virus (HCV) infection in HCC patients. H-cadherin (CDH13), protocadherin-10 (PCDH10), P-cadherin (CDH3), and M-cadherin (CDH15) methylation may have an increased risk of HCC in fewer than 4 studies, and methylated cadherin 8, type 2 (CDH8) and OB-cadherin (CDH11) had a similar OR in HCC and adjacent samples. When HCC samples were compared with normal samples, the analysis of sample type revealed a significantly higher OR in normal blood samples than in normal tissues for hypermethylated CDH1 (50.82 vs 4.44).

CONCLUSION

CDH1 hypermethylation may play a key role in the carcinogenesis of HCC. However, CDH1 hypermethylation was not correlated with clinicopathological features. Methylated CDH13, PCDH10, CDH3, and CDH15, but not methylated CDH8 or CDH11, may lead to an increased risk of HCC. Hypermethylated CDH1 may become a noninvasive blood biomarker. Further studies with more data are necessary.

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.

RYBP Expression Is Regulated by KLF4 and Sp1 and Is Related to Hepatocellular Carcinoma Prognosis

The expression of Ring1- and YY1-binding protein (RYBP) is reduced in several human cancers, but the molecular mechanism(s) have remained elusive. In this study, we used human hepatocellular carcinoma (HCC) cell lines and tissue specimens to study the mechanism and herein report several new findings. First, we cloned and characterized the basal promoter region of the human RYBP gene. We found that the decreased RYBP expression in HCC tissues was not due to promoter sequence variation/polymorphisms or CpG dinucleotide methylation. We identified two transcription factors, KLF4 and Sp1, which directly bind the promoter region of RYBP to induce and suppress RYBP transcription, respectively. We mapped the binding sites of KLF4 and Sp1 on the RYBP promoter. Studies in vitro showed that KLF4 suppresses whereas Sp1 promotes HCC cell growth through modulating RYBP expression. Deregulated KLF4 and Sp1 contributed to decreased expression of RYBP in HCC tumor tissues. Our studies of human HCC tissues indicated that a diminished RYBP level in the tumor (in association with altered KLF4 and Sp1 expression) was statistically associated with a larger tumor size, poorer differentiation, and an increased susceptibility to distant metastasis. These findings help to clarify why RYBP is decreased in HCC and indicate that deregulated KLF4, Sp1, and RYBP may lead to a poorer prognosis. Our findings support the idea that RYBP may represent a target for cancer therapy and suggest that it may be useful as a prognostic biomarker for HCC, either alone or in combination with KLF4 and Sp1.

Molecular alterations in the carcinogenesis and progression of hepatocellular carcinoma: Tumor factors and background liver factors

Although hepatocellular carcinoma (HCC) is associated with poor prognosis worldwide, the molecular mechanisms underlying the carcinogenesis and progression of this disease remain unclear. Several tumor characteristics have previously been demonstrated to be prognostic factors of survival following hepatic resection, or the recurrence of HCC or other types of cancer. Comparisons of normal tissues and HCC tumor tissues have revealed the presence of numerous molecular alterations in HCC, including genetic and epigenetic mechanisms, particularly mutations in certain genes and DNA methylation in the promoter regions of tumor-suppressor genes. A number of studies have previously used array analysis to detect variations in the expression levels of cancer-associated genes and microRNAs, and in DNA methylation. However, an investigation of HCC tumor tissues may not determine the effect of noncancerous liver tissues (background liver) in patients with HCC. As HCC may recur multicentrically following resection, a damaged or chronically diseased HCC background liver may be considered as a pre-cancerous organ. Therefore, the influence of the background liver on HCC requires further study. Detailed studies regarding the background liver may be essential for the improved understanding of the carcinogenesis and progression of this malignancy; however only a few studies have investigated the microenvironment of the HCC background liver. The present review discusses prior molecular studies of hepatocarcinogenesis that focus on HCC and background liver tissues.

Genistein potentiates the effect of 17-beta estradiol on human hepatocellular carcinoma cell line

Background:

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. This cancer may be due to a multistep process with an accumulation of epigenetic alterations in tumor suppressor genes (TSGs), leading to hypermethylation of the genes. Hypermethylation of TSGs is associated with silencing and inactivation of them. It is well-known that DNA hypomethylation is the initial epigenetic abnormality recognized in human tumors. Estrogen receptor alpha (ERα) is one of the TSGs which modulates gene transcription and its hypermethylation is because of overactivity of DNA methyltransferases. Fortunately, epigenetic changes especially hypermethylation can be reversed by pharmacological compounds such as genistein (GE) and 17-beta estradiol (E2) which involve in preventing the development of certain cancers by maintaining a protective DNA methylation. The aim of the present study was to analyze the effects of GE on ERα and DNMT1 genes expression and also apoptotic and antiproliferative effects of GE and E2 on HCC.

Materials and Methods:

Cells were treated with various concentrations of GE and E2 and the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay was used. Furthermore, cells were treated with single dose of GE and E2 (25 μM) and flow cytometry assay was performed. The expression level of the genes was determined by quantitative real-time reverse transcription polymerase chain reaction.

Results:

GE increased ERα and decreased DNMT1 genes expression, GE and E2 inhibited cell viability and induced apoptosis significantly.

Conclusion:

GE can epigenetically increase ERα expression by inhibition of DNMT1 expression which in turn increases apoptotic effect of E2. Furthermore, a combination of GE and E2 can induce apoptosis more significantly.

Ras-association domain family 10 acts as a novel tumor suppressor through modulating MMP2 in hepatocarcinoma

Ras-Association Domain Family 10 (RASSF10) is the last identified member of the RASSF family. The functional characteristics of this new gene in human cancers remain largely unclear. Here, we examined RASSF10 for the biological functions and related molecular mechanisms in hepatocellular carcinoma (HCC). We found that RASSF10 is expressed in normal human liver tissue, but is silenced or down-regulated in 62.5% (5/8) of HCC cell lines. The mean expression level of RASSF10 was significantly lower in primary HCCs compared with their adjacent normal tissues (P<0.005, n=52). The promoter methylation contributes to the inactivation of RASSF10 as demonstrated by bisulfite genomic sequencing and demethylation treatment analyses. Transgenic expression of RASSF10 in silenced HCC cell lines suppressed cell viability, colony formation and inhibited tumor growth in nude mice (QGY7703, P<0.01; HepG2, P<0.05). Furthermore, RASSF10 was shown to induce the cell accumulation in G1 phase with the increase of p27, as well as the decrease of cyclinD1 and CDK2/CDK4. Over-expression of RASSF10 also inhibited HCC cells migration (P<0.01) or invasion (P<0.05). Adhesion genes array revealed that Matrix Metalloproteinase 2 (MMP2) was a downstream effector of RASSF10. RASSF10 acting as a tumor suppressor to inhibit HCC invasion partially mediated by Focal Adhesion Kinase or p38 MAPK to decrease the accumulation of MMP2. Our study suggests that RASSF10 acts as a tumor suppressor for HCC.

NEpiC: a network-assisted algorithm for epigenetic studies using mean and variance combined signals

DNA methylation plays an important role in many biological processes. Existing epigenome-wide association studies (EWAS) have successfully identified aberrantly methylated genes in many diseases and disorders with most studies focusing on analysing methylation sites one at a time. Incorporating prior biological information such as biological networks has been proven to be powerful in identifying disease-associated genes in both gene expression studies and genome-wide association studies (GWAS) but has been under studied in EWAS. Although recent studies have noticed that there are differences in methylation variation in different groups, only a few existing methods consider variance signals in DNA methylation studies. Here, we present a network-assisted algorithm, NEpiC, that combines both mean and variance signals in searching for differentially methylated sub-networks using the protein–protein interaction (PPI) network. In simulation studies, we demonstrate the power gain from using both the prior biological information and variance signals compared to using either of the two or neither information. Applications to several DNA methylation datasets from the Cancer Genome Atlas (TCGA) project and DNA methylation data on hepatocellular carcinoma (HCC) from the Columbia University Medical Center (CUMC) suggest that the proposed NEpiC algorithm identifies more cancer-related genes and generates better replication results.

Molecular pathogenesis of hepatocellular carcinoma and impact of therapeutic advances

Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality and has an increasing incidence worldwide. HCC can be induced by multiple etiologies, is influenced by many risk factors, and has a complex pathogenesis. Furthermore, HCCs exhibit substantial heterogeneity, which compounds the difficulties in developing effective therapies against this highly lethal cancer. With advances in cancer biology and molecular and genetic profiling, a number of different mechanisms involved in the development and progression of HCC have been identified. Despite the advances in this area, the molecular pathogenesis of hepatocellular carcinoma is still not completely understood. This review aims to elaborate our current understanding of the most relevant genetic alterations and molecular pathways involved in the development and progression of HCC, and anticipate the potential impact of future advances on therapeutic drug development.

The effect of acute dichlorodiphenyltrichloroethane exposure on hypermethylation status and down-regulation of p53 and p16INK4a genes in rat liver

The aim of the study was to investigate the early effect of acute dichlorodiphenyltrichloroethane (DDT) exposure on the methylation status of the promoter region of two tumor suppressor genes: p53 and p16(INK4a) (p16) in rat liver. We analyzed their transcript and protein expression profiles concurrently with the examination of transcriptional and protein expression levels of DNA (cytosine-5)-methyltransferase 1 (Dnmt1). Male Wistar rats were treated with a single dose of DDT (57 mg kg(-1) of body weight) and the methylation status of p53 and p16 genes was examined after 24 h using methylation-sensitive restriction analysis-MSRA. The obtained results indicate that DDT induced alternations in methylation of the promoter region in both p53 and p16 genes. In all the tested samples, the promoter CpG islands of p53 (-261, -179, and -450) were methylated within 100% as compared to control samples (0%). The methylation status of the p16 promoter (-11 and +77) was also altered due to exposure to DDT. Methylated cytosines were detectable in 75% of the tested DNA samples. The Real-time PCR and western blot analyses showed a decrease in mRNA and protein levels of p53, respectively, which was related to the increase in DNA synthesis. These relationships were also observed for mRNA and protein expressions of p16, although to a slighter extent. We also showed that hypermethylation in the promoter region of both tumor suppressor genes was consistent with an increased Dnmt1 mRNA level, and this relationship was further confirmed at the protein level of DNMT1. Concluding, our data suggests that epigenetically mediated changes in gene expression may play an important role in the mechanism of DDT toxicity, including carcinogenic action.

RASSF1A and DOK1 Promoter Methylation Levels in Hepatocellular Carcinoma, Cirrhotic and Non-Cirrhotic Liver, and Correlation with Liver Cancer in Brazilian Patients

Hepatocellular carcinoma (HCC) is the second most common cause of cancer mortality worldwide. Most cases of HCC are associated with cirrhosis related to chronic hepatitis B virus or hepatitis C virus infections. Hypermethylation of promoter regions is the main epigenetic mechanism of gene silencing and has been involved in HCC development. The aim of this study was to determine whether aberrant methylation of RASSF1A and DOK1 gene promoters is associated with the progression of liver disease in Brazilian patients. Methylation levels were measured by pyrosequencing in 41 (20 HCC, 9 cirrhotic, and 12 non-cirrhotic) liver tissue samples. Mean rates of methylation in RASSF1A and DOK1 were 16.2% and 12.0% in non-cirrhotic, 26.1% and 19.6% in cirrhotic, and 59.1% and 56.0% in HCC tissues, respectively, showing a gradual increase according to the progression of the disease, with significantly higher levels in tumor tissues. In addition, hypermethylation of RASSF1A and DOK1 was found in the vast majority (88%) of the HCC cases. Interestingly, DOK1 methylation levels in HCC samples were significantly higher in the group of younger (<40 years) patients, and higher in moderately differentiated than in poorly differentiated tumors (p < 0.05). Our results reinforce the hypothesis that hypermethylation of RASSF1A and DOK1 contributes to hepatocarcinogenesis and is associated to clinicopathological characteristics. RASSF1A and DOK1 promoter hypermethylation may be a valuable biomarker for early diagnosis of HCC and a potential molecular target for epigenetic-based therapy.

Methylation of tissue factor pathway inhibitor 2 as a prognostic biomarker for hepatocellular carcinoma after hepatectomy

BACKGROUND AND AIM

Methylation of tissue factor pathway inhibitor 2 (TFPI2) gene has been detected in hepatocellular carcinoma (HCC). However, the clinicopathologcial significance and prognostic value of TFPI2 methylation in HCC remains largely unknown. This study aimed to investigate the prognostic value of TFPI2 methylation in HCC after hepatectomy.

METHODS

Methylation status of TFPI2 gene was examined in 178 surgical specimens of HCC and 20 normal liver samples using methylation-specific polymerase chain reaction.

RESULTS

Methylation of TFPI2 gene was detected in 44.9% (80 of 178) of primary HCC samples, 10.7% (19 of 178) of the corresponding non-tumorous liver samples, and 5.0% (1/20) of the normal liver samples. The mRNA concentrations of TFPI2 in primary HCC tissues were significantly lower than those in corresponding non-tumorous liver tissues and those in normal liver tissues. TFPI2 methylation was significantly associated with higher TNM stage. Patients with TFPI2 methylation demonstrated a significantly poorer prognosis than those without TFPI2 methylation for both overall survival and disease-free survival (P < 0.001, respectively). Multivariate analyses confirmed that TFPI2 methylation was an independent prognostic factor for both overall survival (P = 0.002) and disease-free survival (P = 0.000) in HCC after hepatectomy. Moreover, TFPI2 methylation was found to be the only independent predictor for early tumor recurrence of HCC after resection based on multivariate analysis (P = 0.002).

CONCLUSIONS

Methylation of TFPI2 predicts high risk of advanced tumor stage, early tumor recurrence, and poor prognosis, and it could be a potential prognostic biomarker in patients with HCC after hepatectomy.