Mutations in TP53, CTNNB1 and PIK3CA genes in hepatocellular carcinoma associated with hepatitis B and hepatitis C virus infections

Molecular alterations in hepatocellular carcinoma associated with hepatitis B and hepatitis C infections

Chronic infections with hepatitis B (HBV) and hepatitis C viruses (HCV) are the leading cause of cirrhosis and hepatocellular carcinoma (HCC) worldwide. Both viruses encode multifunctional regulatory proteins activating several oncogenic pathways, which induce accumulation of multiple genetic alterations in the infected hepatocytes. Gene mutations in HBV- and HCV-induced HCCs frequently impair the TP53, Wnt/b-catenin, RAS/RAF/MAPK kinase and AKT/mTOR pathways, which represent important anti-cancer targets. In this review, we highlight the molecular mechanisms underlying the pathogenesis of primary liver cancer, with particular emphasis on the host genetic variations identified by high-throughput technologies. In addition, we discuss the importance of genetic alterations, such as mutations in the telomerase reverse transcriptase (TERT) promoter, for the diagnosis, prognosis, and tumor stratification for development of more effective treatment approaches.

Genomic Characterization and Comparison of Multi-Regional and Pooled Tumor Biopsy Specimens

A single tumor biopsy specimen is typically used in cancer genome studies. However, it may represent incompletely the underlying mutational and transcriptional profiles of tumor biology. Multi-regional biopsies have the advantage of increased sensitivity for genomic profiling, but they are not cost-effective. The concept of an alternative method such as the pooling of multiple biopsies is a challenge. In order to determine if the pooling of distinct regions is representative at the genomic and transcriptome level, we performed sequencing of four regional samples and pooled samples for four cancer types including colon, stomach, kidney and liver cancer. Subsequently, a comparative analysis was conducted to explore differences in mutations and gene expression profiles between multiple regional biopsies and pooled biopsy for each tumor. Our analysis revealed a marginal level of regional difference in detected variants, but in those with low allele frequency, considerable discrepancies were observed. In conclusion, sequencing pooled samples has the benefit of detecting many variants with moderate allele frequency that occur in partial regions, but it is not applicable for detecting low-frequency mutations that require deep sequencing.

Significance of hepatitis virus infection in the oncogenic initiation of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Chronic infection of hepatitis B virus (HBV) and/or hepatitis C virus (HCV) is a major risk factor in the development of the HCC, independently from excessive alcohol abuse and metabolic disease. Since the biology of HBV and HCV is different, their oncogenic effect may go through different mechanisms, direct and/or indirect. Viral hepatitis infection is associated with cellular inflammation, oxidative stress, and DNA damage, that may lead to subsequent hepatic injuries such as chronic hepatitis, fibrosis, cirrhosis, and finally HCC. Direct oncogenic properties of these viruses are related with their genotypic characteristics and the ability of viral proteins to interact with host proteins, thus altering the molecular pathways balance of the cells. In addition, the integration of HBV DNA, especially the gene S and X, in a particular site of the host genome can disrupt chromosomal stability and may activate various oncogenic mechanisms, including those in hematopoietic cells. Recently, several studies also had demonstrated that viral hepatitis could trigger the population of hepatic cancer stem cells. This review summarize available pre-clinical and clinical data in literature regarding oncogenic properties of HBV and HCV in the early initiation of HCC.

Glucose-regulated protein 94 mediates metastasis by CCT8 and the JNK pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death worldwide. Cancer metastasis is a major obstacle in clinical cancer therapy. The mechanisms underlying the metastasis of HCC remain unclear. Glucose-regulated protein 94 (GRP94) is a key protein involved in mediating cancer progression, and it is highly expressed in HCC specimens. However, the role of GRP94 in cancer metastasis is unclear. A specific short hairpin RNA (shRNA) was employed to knock down GRP94 gene expression in HCC cell lines. Wound-healing migration, transwell migration, and invasion assays were performed to determine the migration and invasive ability of HCC cells. We demonstrated that silencing GRP94 inhibited HCC cell wound healing, migration, and invasion. Furthermore, our findings indicated that GRP94 knockdown might attenuate HCC cell metastasis by inhibiting CCT8/c-Jun/EMT signaling. Our study indicated that silencing GRP94 significantly reduced the migration and invasion abilities of HCC cells. Moreover, depleting GRP94 inhibited cell migration and invasion by downregulating CCT8/c-Jun signaling. Thus, our data suggest that the GRP94/CCT8/c-Jun/EMT signaling cascade might be a new therapeutic target for HCC.

Cancer prevention in HIV-infected populations

People living with human immunodeficiency virus (HIV) are living longer since the advent of effective combined antiretroviral therapy (cART). While cART substantially decreases the risk of developing some cancers, HIV-infected individuals remain at high risk for Kaposi sarcoma, lymphoma, and several solid tumors. Currently HIV-infected patients represent an aging group, and malignancies have become a leading cause of morbidity and mortality. Tailored cancer-prevention strategies are needed for this population. In this review we describe the etiologic agents and pathogenesis of common malignancies in the setting of HIV, as well as current evidence for cancer prevention strategies and screening programs.

ARID2, p110α, p53, and β-catenin protein expression in hepatocellular carcinoma and clinicopathologic implications

ARID2 (ARID2), CTNNB1 (β catenin), tumor protein 53 (p53), and PIK3CA (p110α) mutations are implicated in hepatocellular carcinoma (HCC); and previous work has contributed to thorough molecular characterization of these events. However, studies that assess the impact of these mutations on downstream protein expression, especially those that evaluate all 4 cancer markers simultaneously, are relatively lacking. Hence, the present study uses immunohistochemistry to assess protein expression patterns of ARID2, β-catenin, p53, and p110α in HCCs and adjacent nonneoplastic cirrhotic tissues from 58 explanted livers. Notably, this study is the first to our knowledge to investigate ARID2 protein expression in the liver. The frequency of ARID2 mutations detected using our immunohistochemistry method was similar to that reported in previous molecular studies. Furthermore, we found that loss of ARID2 protein expression may be associated with recurrence, although further studies must be done to validate these findings in a larger population. We found that expression patterns of the 4 cancer markers were independent of each other, suggesting separate pathways of hepatocarcinogenesis. We also did not observe an association between viral etiology and protein expression. Consistent with previous studies, overexpression of p53 correlated with poor differentiation. Lastly, 17.5% of HCCs paradoxically had diffuse loss of the oncoprotein p110α compared with strong expression in background cirrhotic liver. The exact mechanism is unclear, but enigmatic loss of oncoprotein function has been described in other carcinomas and could potentially have significant implications for the use of mechanistic target of rapamycin (mTOR) drug therapies.

Genome-wide mutational spectra analysis reveals significant cancer-specific heterogeneity

Cancer is widely recognized as a genetic disease in which somatic mutations are sequentially accumulated to drive tumor progression. Although genomic landscape studies are informative for individual cancer types, a comprehensive comparative study of tumorigenic mutations across cancer types based on integrative data sources is still a pressing need. We systematically analyzed ~10(6) non-synonymous mutations extracted from COSMIC, involving ~8000 genome-wide screened samples across 23 major human cancers at both the amino acid and gene levels. Our analysis identified cancer-specific heterogeneity that traditional nucleotide variation analysis alone usually overlooked. Particularly, the amino acid arginine (R) turns out to be the most favorable target of amino acid alteration in most cancer types studied (P < 10(-9), binomial test), reflecting its important role in cellular physiology. The tumor suppressor gene TP53 is mutated exclusively with the HYDIN, KRAS, and PTEN genes in large intestine, lung, and endometrial cancers respectively, indicating that TP53 takes part in different signaling pathways in different cancers. While some of our analyses corroborated previous observations, others indicated relevant candidates with high priority for further experimental validation. Our findings have many ramifications in understanding the etiology of cancer and the underlying molecular mechanisms in particular cancers.

A genetic screen reveals Foxa3 and TNFR1 as key regulators of liver repopulation

Wangensteen et al. employed a parallel screen to test the impact of 43 selected genes on liver repopulation in the Fah^−/− mouse model of hereditary tyrosinemia. The transcription factor Foxa3 was a strong promoter of liver regeneration, while tumor necrosis factor receptor 1 (TNFR1) was the most significant suppressor of repopulation among all of the genes tested.

The fundamental question of which genes are most important in controlling liver regeneration remains unanswered. We employed a parallel screen to test the impact of 43 selected genes on liver repopulation in the Fah^−/− mouse model of hereditary tyrosinemia. We discovered that the transcription factor Foxa3 was a strong promoter of liver regeneration, while tumor necrosis factor receptor 1 (TNFR1) was the most significant suppressor of repopulation among all of the genes tested. Our approach enabled the identification of these factors as important regulators of liver repopulation and potential drug targets for the promotion of liver repopulation.

Hepatitis C virus prevalence and genotyping among hepatocellular carcinoma patients in Baghdad

Hepatocellular carcinoma (HCC) is the third most common cause for cancer death in the world, now being especially linked to chronic hepatitis C virus (HCV) infection. This case-control study consisting of 65 HCC patients and 82 patients with other malignant tumours as controls was conducted to determine the association of HCV markers with HCC. Serum of each participant was obtained for detection of HCV Ab and RNA by DNA enzyme immunoassay (DEIA). Twenty six per cent (26.0%) of HCC patients had positive anti-HCV which was significantly greater than the control group (p=0.001). HCC patients significantly have a risk of exposure to HCV infection almost 3 times than the control group (OR=2.87, 95% C.I=1.1-7). Anti-HCV seropositive rate was significantly (p=0.03) higher among old age HCC patients and increases with age. Males with HCC significantly showed to have more than 9 times risk of exposure to HCV infection (OR=9.375, 95 % CI=1.299-67.647) than females. HCV-RNA seropositive rate was (70.8%) significantly higher among HCC patients compared to (22.2%) the control group (p=0.019). The most prevalent genotype (as a single or mixed pattern of infection) was HCV- 1b. This study detected a significantly higher HCV seropositive rate of antibodies and RNA in HCC patients.

Integrative analysis of aberrant Wnt signaling in hepatitis B virus-related hepatocellular carcinoma

AIM: To comprehensively understand the underlying molecular events accounting for aberrant Wnt signaling activation in hepatocellular carcinoma (HCC).

METHODS: This study was retrospective. The HCC tissue specimens used in this research were obtained from patients who underwent liver surgery. The Catalogue of Somatic Mutations in Cancer (COSMIC) database was searched for the mutation statuses of CTNNB1, TP53, and protein degradation regulator genes of CTNNB1. Dual-luciferase reporter assay was performed with TOP/FOP reporters to detect whether TP53 gain-of-function (GOF) mutations could enhance the transcriptional activity of Wnt signaling. Methylation sensitive restriction enzyme-quantitative PCR was used to explore the methylation status of CpG islands located in the promoters of APC, SFRP1, and SFRP5 in HCCs with different risk factors. Finally, nested-reverse transcription PCR was performed to examine the integration of HBx in front of LINE1 element and the existence of HBx-LINE1 chimeric transcript in Hepatitis B virus-related HCC. All results in this article were analyzed with the software SPSS version 19.0 for Windows, and different groups were compared by χ² test as appropriate.

RESULTS: Based on the data from COSMIC database, compared with other solid tumors, mutation frequency of CTNNB1 was significantly higher in HCC (P < 0.01). The rate of CTNNB1 mutation was significantly less frequent in Hepatitis B virus-related HCC than in other etiologies (P < 0.01). Dual-luciferase reporter system and TOP/FOP reporter assays confirmed that TP53 GOF mutants were able to enhance the transcriptional ability of Wnt signaling. An exclusive relationship between the status of TP53 and CTNNB1 mutations was observed. However, according to the COSMIC database, TP53 GOF mutation is rare in HCC, which indicates that TP53 GOF mutation is not a reason for the aberrant activation of Wnt signaling in HCC. APC and AXIN1 were mutated in HCC. By using methylation sensitive restriction enzyme-quantitative PCR, hypermethylation of APC was detected in HCC with different risk factors, whereas SFRP1 and SFRP5 were not hypermethylated in any of the HCC etiologies, which indicates that the mutation of APC and AXIN1, together with the methylation of APC could take part in the overactivation of Wnt signaling. Nested-reverse transcription PCR failed to detect the integration of HBx before the LINE1 element, or the existence of an HBx-LINE1 chimeric transcript, suggesting that integration could not play a role in the aberrant activation of Wnt signaling in HCC.

CONCLUSION: In HCC, genetic/epigenetic aberration of CTNNB1 and its protein degradation regulators are the major cause of Wnt signaling overactivation.

Molecular targeted therapy in hepatocellular carcinoma: from biology to clinical practice and future

OPINION STATEMENT

Hepatocellular carcinoma (HCC) is one of the most lethal cancers globally, particularly in certain regions of the world. Although the major risk factors for HCC have been identified, the specific mechanisms driving hepatocarcinogenesis remain unclear. Sorafenib is the only systemic therapy that has demonstrated an overall survival benefit in patients with advanced HCC and does so primarily through antiangiogenic activity. However, that actual benefit is still relatively small. Extensive research has focused on targeting dysfunctional molecular pathways in HCC. Despite promising preclinical and early-phase studies, other agents have failed to expand upon the efficacy of sorafenib in large-scale randomized trials. As the development of treatment options in the post-sorafenib setting is ongoing, more efforts are being focused on (1) evaluation of molecular agents targeting pathogenic, HCC-specific pathways; (2) the combination of targeted and cytotoxic therapies in selected subgroups; and (3) the combination of systemic and locoregional therapies in various settings. This article provides a review of recently completed and ongoing studies of molecular targeted agents in HCC, including a brief description of the biologic rationale behind these agents.

Decreased expression of ARID1A associates with poor prognosis and promotes metastases of hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is a common malignancy worldwide, which is especially prevalent in Asia. Elucidating the molecular basis of HCC is crucial to develop targeted diagnostic tools and novel therapies. Recent studies have identified AT-rich interactive domain-containing protein 1A (ARID1A) as a broad-spectrum tumor suppressor. We evaluated the clinical implications of decreased ARID1A expression in HCC, and investigated the mechanisms of ARID1A-mediated tumor suppression.

Methods

Quantitative PCR, western blotting, immunohistochemical analysis of ARID1A mRNA and protein expression was conducted in 64 paired HCC and adjacent non-tumorous tissues. ARID1A function was evaluated in vitro in MHCC-97H and Huh7 HCC cell lines, and in vivo in a xenografted HCC tumor model.

Results

ARID1A mRNA and protein expression were significantly decreased in HCC tissues, and decreased expression was significantly associated with overall metastasis, including local lymph node and distant metastasis, and poor prognosis. ARID1A knockdown promoted HCC cell migration and invasion in vitro, whereas overexpression of ARID1A inhibited migration and invasion. E-cadherin levels were closely correlated with ARID1A expression, suggesting a role in migration and invasion. In addition, ARID1A and E-cadherin (CDH1) expression were found to be regulated in a coordinated fashion in HCC samples. Furthermore, ARID1A knockdown significantly increased HCC tumor growth and lung metastasis in vivo.

Conclusions

ARID1A served as an important tumor suppressor. Decreased expression of ARID1A was associated with tumor progression, metastasis, and reduced overall survival in mice and humans. ARID1A could represent a promising candidate therapeutic target for HCC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0164-3) contains supplementary material, which is available to authorized users.

Targeting Wnts at the source--new mechanisms, new biomarkers, new drugs

Wnt signaling is dysregulated in many cancers and is therefore an attractive therapeutic target. The focus of drug development has recently shifted away from downstream inhibitors of β-catenin. Active inhibitors of Wnt secretion and Wnt/receptor interactions have been developed that are now entering clinical trials. Such agents include inhibitors of Wnt secretion, as well as recombinant proteins that minimize Wnt-Frizzled interactions. These new therapies arrive together with the recent insight that cancer-specific upregulation of Wnt receptors at the cell surface regulates cellular sensitivity to Wnts. Loss-of-function mutations in RNF43 or ZNRF3 and gain-of-function chromosome translocations involving RSPO2 and RSPO3 are surprisingly common and markedly increase Wnt/β-catenin signaling in response to secreted Wnts. These mutations may be predictive biomarkers to select patients responsive to newly developed upstream Wnt inhibitors.

Chemopreventive potential of green tea catechins in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), which is a common malignancy worldwide, usually develops in a cirrhotic liver due to hepatitis virus infection. Metabolic syndrome, which is frequently complicated by obesity and diabetes mellitus, is also a critical risk factor for liver carcinogenesis. Green tea catechins (GTCs) may possess potent anticancer and chemopreventive properties for a number of different malignancies, including liver cancer. Antioxidant and anti-inflammatory activities are key mechanisms through which GTCs prevent the development of neoplasms, and they also exert cancer chemopreventive effects by modulating several signaling transduction and metabolic pathways. Furthermore, GTCs are considered to be useful for the prevention of obesity- and metabolic syndrome-related carcinogenesis by improving metabolic disorders. Several interventional trials in humans have shown that GTCs may ameliorate metabolic abnormalities and prevent the development of precancerous lesions. The purpose of this article is to review the key mechanisms by which GTCs exert chemopreventive effects in liver carcinogenesis, focusing especially on their ability to inhibit receptor tyrosine kinases and improve metabolic abnormalities. We also review the evidence for GTCs acting to prevent metabolic syndrome-associated liver carcinogenesis.

AT-rich interactive domain 2, p110α, p53, and β-catenin protein expression in hepatocellular carcinoma and clinicopathologic implications

AT-rich interactive domain 2 (ARID2), catenin (cadherin-associated protein), beta 1, 88kDa (β-catenin), tumor protein 53 (p53), and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (p110α) mutations are implicated in hepatocellular carcinoma (HCC); and previous work has contributed to thorough molecular characterization of these events. However, studies that assess the impact of these mutations on downstream protein expression, especially those that evaluate all 4 cancer markers simultaneously, are relatively lacking. Hence, the present study uses immunohistochemistry to assess protein expression patterns of ARID2, β-catenin, p53, and p110α in HCCs and adjacent nonneoplastic cirrhotic tissues from 58 explanted livers. Notably, this study is the first to our knowledge to investigate ARID2 protein expression in the liver. The frequency of ARID2 mutations detected using our immunohistochemistry method was similar to that reported in previous molecular studies. Furthermore, we found that loss of ARID2 protein expression may be associated with recurrence, although further studies must be done to validate these findings in a larger population. We found that expression patterns of the 4 cancer markers were independent of each other, suggesting separate pathways of hepatocarcinogenesis. We also did not observe an association between viral etiology and protein expression. Consistent with previous studies, overexpression of p53 correlated with poor differentiation. Lastly, 17.5% of HCCs paradoxically had diffuse loss of the oncoprotein p110α compared with strong expression in background cirrhotic liver. The exact mechanism is unclear, but enigmatic loss of oncoprotein function has been described in other carcinomas and could potentially have significant implications for the use of targeted mechanistic target of rapamycin (serine/threonine kinase) drug therapies.

An overview of new biomolecular pathways in pathogen-related cancers

Cancer molecular pathways are combinations of metabolic processes deregulated in neoplastic cells. Besides pathways specific to tissues from which cancers originate, common neoplastic traits are present among most tumors. Hanahan and Weinberg have described the most critical 'hallmarks' shared by many cancer types. In recent years, cancer stem cell specific properties and pathways have also been identified. Other altered pathways are peculiar of cancer type and cancer stage, even in different cancer stem cell types. In pathogen-related tumors, the alteration of inflammatory and immunologic response along with impairment of cell cycle control represents key molecular events of tumor progression. This article summarizes the recent discoveries of new altered pathways in cancer and their importance in cancer diagnosis and tailored therapies.

Wnt/beta-catenin signaling pathway in hepatocellular carcinomas cases from Colombia

BACKGROUND AND AIM

Hepatocellular carcinoma (HCC) is the most common primary liver cancer diagnosed worldwide. Deregulation of Wnt/beta-catenin pathway has been associated with the development of HCC in a substantial number of cases in Europe and far less in Asia. Nothing is known about this pathway in HCC cases from South America. This study aimed to investigate the frequency of mutations in beta-catenin gene (CTNNB1) and the subcellular localization of beta-catenin in HCC cases from Colombia.

MATERIAL AND METHODS

We determine by direct sequencing the frequency of mutations in exon 3 of CTNNB1 gene and by immunohistochemistry the subcellular localization of beta-catenin in 54 samples of HCC obtained from three pathology units in Bogota and Medellin cities.

RESULTS

Only three HCC cases (5.6%) were found mutated at residues (G34E, S45P, P44S, T41I) important for phosphorylation and ubiquitination of beta-catenin protein. Strikingly, nuclear or cytoplasmic accumulation of beta-catenin, hallmark of Wnt pathway activation, was found in 42.6% HCC cases (23/54). Interestingly, beta-catenin accumulation was significantly more frequent in young patients and hepatitis B virus-related HCC.

CONCLUSIONS

Although, CTNNB1 exon 3 mutations are not frequent in HCC from Colombian patients, our findings indicate that Wnt/beta-catenin signaling is activated in 42.6% of HCC samples. Furthermore, Wnt signaling was demonstrated in HCC cases associated of HBV infection, one of the most important HCC risk factors in Colombia.

Alcohol and HCV: implications for liver cancer

Liver cancers are one of the deadliest known malignancies which are increasingly becoming a major public health problem in both developed and developing countries. Overwhelming evidence suggests a strong role of infection with hepatitis B and C virus (HBV and HCV), alcohol abuse, as well as metabolic diseases such as obesity and diabetes either individually or synergistically to cause or exacerbate the development of liver cancers. Although numerous etiologic mechanisms for liver cancer development have been advanced and well characterized, the lack of definite curative treatments means that gaps in knowledge still exist in identifying key molecular mechanisms and pathways in the pathophysiology of liver cancers. Given the limited success with current therapies and preventive strategies against liver cancer, there is an urgent need to identify new therapeutic options for patients. Targeting HCV and or alcohol-induced signal transduction, or virus-host protein interactions may offer novel therapies for liver cancer. This review summarizes current knowledge on the mechanistic development of liver cancer associated with HCV infection and alcohol abuse as well as highlights potential novel therapeutic strategies.

Infección por el virus de la hepatitis C en individuos transfundidos antes de 1994 en Antioquia, Colombia

Introducción: la infección por el virus de la hepatitis C es un problema de salud pública. Según datos de la Organización Mundial de la Salud, se estiman 184 millones de casos de infección por VHC en el mundo. El principal factor de riesgo en países en desarrollo corresponde a la transfusión de componentes sanguíneos. En Colombia, en 1993, se reglamentó el tamizaje serológico en los bancos de sangre para diferentes agentes infecciosos, incluido el VHC; sin embargo, los datos de infección por VHC en la población transfundida antes de esta fecha es limitada. Objetivo: describir la frecuencia de infección por el VHC en una población de individuos transfundidos antes de 1994 en Antioquia. Materiales y Métodos: un total de 166 individuos transfundidos antes de 1994 aceptaron participar en el estudio. A partir de las muestras de suero se realizó la detección de anticuerpos totales contra el VHC (anti-VHC) mediante prueba de ELISA y en las muestras positivas se determinó la presencia del genoma viral por RT-PCR de la región no codificante 5’. Resultados y conclusiones: en el población de estudio se encontró una frecuencia de anticuerpos anti-VHC de 6,6% (11/166) y presencia del genoma del VHC en 7/11 de las muestras; el genotipo 1 se identificó en 4 de las muestras. No se encontró asociación de otros factores de riesgo diferentes a transfusión en los individuos con marcadores de infección por el VHC. Este estudio aporta datos a la epidemiología de la infección por el VHC en Colombia.

A small-molecule modulator of the tumor-suppressor miR34a inhibits the growth of hepatocellular carcinoma

Small molecules that restore the expression of growth-inhibitory microRNAs (miRNA) downregulated in tumors may have potential as anticancer agents. miR34a functions as a tumor suppressor and is downregulated or silenced commonly in a variety of human cancers, including hepatocellular carcinoma (HCC). In this study, we used an HCC cell-based miR34a luciferase reporter system to screen for miR34a modulators that could exert anticancer activity. One compound identified as a lead candidate, termed Rubone, was identified through its ability to specifically upregulate miR34a in HCC cells. Rubone activated miR34a expression in HCC cells with wild-type or mutated p53 but not in cells with p53 deletions. Notably, Rubone lacked growth-inhibitory effects on nontumorigenic human hepatocytes. In a mouse xenograft model of HCC, Rubone dramatically inhibited tumor growth, exhibiting stronger anti-HCC activity than sorafenib both in vitro and in vivo. Mechanistic investigations showed that Rubone decreased expression of cyclin D1, Bcl-2, and other miR34a target genes and that it enhanced the occupancy of p53 on the miR34a promoter. Taken together, our results offer a preclinical proof of concept for Rubone as a lead candidate for further investigation as a new class of HCC therapeutic based on restoration of miR34a tumor-suppressor function.

Analysis of protein interaction networks for the detection of candidate hepatitis B and C biomarkers

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infection are the major causes of chronic liver disease, cirrhosis and hepatocellular carcinoma (HCC). The resolution or chronicity of acute infection is dependent on a complex interplay between virus and innate/adaptive immunity. The mechanisms that lead a significant proportion of patients to more severe liver disease are not clearly defined and involve virus induced host gene/protein alterations. The utilization of protein interaction networks (PINs) is expected to identify novel aspects of the disease concerning the patients' immune response to virus as well as the main pathways that are involved in the development of fibrosis and HCC. In this study, we designed several PINs for HBV and HCV and employed topological, modular, and functional analysis techniques in order to determine significant network nodes that correspond to prominent candidate biomarkers. The networks were built using data from various interaction databases. When the overall PINs of HBV and HCV were compared, 48 nodes were found in common. The implementation of a statistical ranking procedure indicated that three of them are of higher importance.

Next generation sequencing reveals microRNA isoforms in liver cirrhosis and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents the major histological subtype of liver cancer. Tumorigenic changes in hepatic cells potentially result from aberrant expression of microRNAs (miRNAs). Individual microRNA gene may give rise to miRNAs of different length, named isomiRNAs that proved to be functionally relevant. Since microRNA length heterogeneity in hepatic tissue has not been described before, we employed next-generation sequencing to comprehensively analyze microRNA transcriptome in HCC tumors (n=24) and unaffected tissue adjacent to tumors (n=24), including samples with (n=15) and without cirrhosis (n=9). We detected 374 microRNAs expressed in liver, including miR-122-5p that constituted over 39% of the hepatic miRnome. Among the liver expressed miRs, the levels of 64 significantly differed between tumor and control samples (FDR<0.05, fold change>2). Top deregulated miRNAs included miR-1269a (T/N=22.95), miR-3144-3p (T/N=5.24), miR-183-5p (T/N=4.63), miR-10b-5p (T/N=3.87), miR-490-3p (T/N=0.13), miR-199a-5p (T/N=0.17), miR-199a-3p/miR-199b-3p (T/N=0.19), miR-214-5p (T/N=0.20) and miR-214-3p (T/N=0.21). Almost all miRNA genes produced several mature molecules differing in length (isomiRNAs). The reference sequence was not the most prevalent in 38.6% and completely absent in 10.5% of isomiRNAs. Over 26.1% of miRNAs produced isoforms carrying≥2 alternative seed regions, of which 35.5% constituted novel, previously unknown seeds. This fact sheds new light on the percentage of the human genome regulated by microRNAs and their variants. Among the most deregulated miRNAs, miR-199a-3p/miR-199b-3p (T/N fold change=0.18, FDR=0.005) was expressed in 9 isoforms with 3 different seeds, concertedly leading to upregulation of TGF-beta signaling pathway (OR=1.99; p=0.004). In conclusion, the study reveals the comprehensive miRNome of hepatic tissue and provides new tools for investigation of microRNA-dependent pathways in cirrhotic liver and hepatocellular carcinoma. This article is part of a Directed Issue entitled: Rare Cancers.

Obesity-associated mechanisms of hepatocarcinogenesis

Obesity has been recognized as a key component of the metabolic syndrome, a cluster of risk factors associated with diabetes and cardiovascular morbidity. In addition, obesity has been linked to higher frequency of cancers in a variety of tissues including the liver. Liver cancer most often occurs as hepatocellular carcinoma (HCC) complicating cirrhosis due to chronic viral infection or toxic injury and remains the third leading cause of cancer death in the world. However, HCC is increasingly diagnosed among individuals with obesity and related disorders. As these metabolic conditions have become globally prevalent, they coexist with well-established risk factors of HCC and create a unique challenge for the liver as a chronically diseased organ. Obesity-associated HCC has recently been attributed to molecular mechanisms such as chronic inflammation due to adipose tissue remodeling and pro-inflammatory adipokine secretion, ectopic lipid accumulation and lipotoxicity, altered gut microbiota, and disrupted senescence in stellate cells, as well as insulin resistance leading to increased levels of insulin and insulin-like growth factors. These mechanisms synergize with those occurring in chronic liver disease resulting from other etiologies and accelerate the development of HCC before or after the onset of cirrhosis. Increasingly common interactions between oncogenic pathways linked to obesity and chronic liver disease may explain why HCC is one of the few malignancies with rising incidence in developed countries. Better understanding of this complex process will improve our strategies of cancer prevention, prediction, and surveillance.

Multiple interactive factors in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is the fifth most prevalent cancer and the third most frequent cause of cancer mortality globally. Each year there are approximately 630,000 new cases of HCC in the world and more than half of the new cases occur in China. Major risk factors of HCC include HBV or HCV infection, alcoholic liver disease, and nonalcoholic fatty liver disease. Most of these risk factors lead to chronic hepatitis and cirrhosis, which is present in 80-90% of HCC patients. Hepatocarcinogenesis has been regarded as a multi-stage process involving multiple genetic or environmental factors. Interaction and cross-regulation of distinct factors synergistically contributes to HCC occurrence. A comprehensive knowledge on the multiple factors and their interaction in hepatocarcinogenesis is necessary to improve the effectiveness of HCC intervention. In this review, we will focus on the recent progress made in understanding the mechanisms of hepatocarcinogenesis and discuss some potential issues or challenges in this area.

Genomic insights into WNT/β-catenin signaling

The canonical WNT pathway regulates the stability of the proto-oncogene β-catenin and is aberrantly activated in many cancer types. Studies in a wide range of experimental models confirm that β-catenin activity is required for tumor initiation in cancers where this pathway is deregulated. However, to date this pathway has proven to be challenging to target therapeutically. Moreover, several lines of evidence suggest that other components and regulators of β-catenin exist. Here we will describe recent structural and functional studies describing genomic alterations and new regulators of β-catenin that lead to aberrant activation of the WNT/β-catenin pathway. These findings provide new insights into the biology of WNT/β-catenin signaling and suggest potential therapeutic opportunities.

Pharmaceutical and nutraceutical approaches for preventing liver carcinogenesis: chemoprevention of hepatocellular carcinoma using acyclic retinoid and branched-chain amino acids

The poor prognosis for patients with hepatocellular carcinoma (HCC) is associated with its high rate of recurrence in the cirrhotic liver. Therefore, more effective strategies need to be urgently developed for the chemoprevention of this malignancy. The malfunction of retinoid X receptor α, a retinoid receptor, due to phosphorylation by Ras/mitogen-activated protein kinase is closely associated with liver carcinogenesis and may be a promising target for HCC chemoprevention. Acyclic retinoid (ACR), a synthetic retinoid, can prevent HCC development by inhibiting retinoid X receptor α phosphorylation and improve the prognosis for this malignancy. Supplementation with branched-chain amino acids (BCAA), which are used to improve protein malnutrition in patients with liver cirrhosis, can also reduce the risk of HCC in obese cirrhotic patients. In experimental studies, both ACR and BCAA exert suppressive effects on HCC development and the growth of HCC cells. In particular, combined treatment with ACR and BCAA cooperatively inhibits the growth of HCC cells. Furthermore, ACR and BCAA inhibit liver tumorigenesis associated with obesity and diabetes, both of which are critical risk factors for HCC development. These findings suggest that pharmaceutical and nutraceutical approaches using ACR and BCAA may be promising strategies for preventing HCC and improving the prognosis of this malignancy.