Frequent k- ras -2 mutations and p16(INK4A)methylation in hepatocellular carcinomas in workers exposed to vinyl chloride

Exploring non-coding RNA mechanisms in hepatocellular carcinoma: implications for therapy and prognosis

Hepatocellular carcinoma (HCC) is a significant contributor to cancer-related deaths in the world. The development and progression of HCC are closely correlated with the abnormal regulation of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Important biological pathways in cancer biology, such as cell proliferation, death, and metastasis, are impacted by these ncRNAs, which modulate gene expression. The abnormal expression of non-coding RNAs in HCC raises the possibility that they could be applied as new biomarkers for diagnosis, prognosis, and treatment targets. Furthermore, by controlling the expression of cancer-related genes, miRNAs can function as either tumor suppressors or oncogenes. On the other hand, lncRNAs play a role in the advancement of cancer by interacting with other molecules within the cell, which, in turn, affects processes such as chromatin remodeling, transcription, and post-transcriptional processes. The importance of ncRNA-driven regulatory systems in HCC is being highlighted by current research, which sheds light on tumor behavior and therapy response. This research highlights the great potential of ncRNAs to improve patient outcomes in this difficult disease landscape by augmenting the present methods of HCC care through the use of precision medicine approaches.

Novel deoxyribonucleic acid methylation perturbations in workers exposed to vinyl chloride

To explore the epigenetic mechanism of deoxyribonucleic acid (DNA) damage induced by vinyl chloride (VC), we studied the micronuclei of peripheral blood lymphocytes in 193 subjects (92 in a VC exposure group employed in a chlorine-alkali plant; 101 in a control group employed in a power plant) and selected three pairs from the subjects (exposed and control) for whole-genome bisulfite sequencing (WGBS). The results showed that the rate of micronucleus formation in the VC exposure group was higher than that of control group (6.05 ± 3.28‰ vs. 2.01 ± 1.79‰). A total of 9534 differentially methylated regions (DMRs) were identified by WGBS, of which 4816 were hypomethylated and 4718 were hypermethylated. The Kyoto encyclopedia of genes and genomes (KEGG) pathway and gene ontology (GO) analyses showed the top three KEGG pathways were cancer , neuroactive ligand-receptor interaction, and axon guidance, and the top three GO-BP pathways enriched were multicellular organismal process, developmental process, and anatomical structure development. In the most enriched DMR pathway (pathways in cancer), we found that BCL2, TJP2, TAOK1, PFKFB3, LIPI, and LIPH were hypermethylated, and the methylation levels of BNIP1 and GRPEL2 were decreased. The methylation of differentially methylated genes (DMGs) mentioned above were verified by methylation-specific PCR (MSP) and agarose gel electrophoresis (AGE) in 50 pairs of subjects, where the coincidence rate was 60-100%. In conclusion, the epigenetic perturbations of specific DMGs (BCL2, TJP2, TAOK1, PFKFB3, LIPI, LIPH, BNIP1, and GRPEL2) may be associated with DNA damage from vinyl chloride exposure.

Chemical Risk Factors of Primary Liver Cancer: An Update

Primary liver cancer has the sixth highest incidence and fourth highest cancer mortality worldwide. Hepatitis B is the leading cause of liver cancer, though its incidence is decreasing with vaccination. Alcohol is the leading cause of liver transplant, cirrhosis, and cancer in the developed world, and is projected to surpass hepatitis B as the leading hepatic cancer etiology worldwide. Tobacco smoking has shown a positive association with liver cancer in a majority of studies, though not all. Aflatoxin, a mycotoxin produced by Aspergillus, is estimated to account for 3–20% of global liver cancer cases, 40% of which occur in sub-Saharan Africa. These statistics are confounded by the prevalence of hepatitis B, which may have a synergistic effect on hepatic carcinogenesis. Aflatoxin is ingested and likely inhaled from agricultural products, placing farmers, food processors, and textile workers in developing nations at risk. Vinyl-chloride is used in the production of PVC plastics and causes rare liver angiosarcoma, hepatocellular carcinoma, and other neoplasms. Arsenic and cadmium are naturally-occurring, hepatocarcinogenic metals with high occupational exposure in industries involving coal, metals, plastics, and batteries. Millions of laborers in waste-disposal and manufacturing are exposed to organic solvents and N-nitrosamines, which vary from carcinogenic (group 1) to possibly carcinogenic (group 2B) in their IARC designation. Insecticide DDT is possibly hepatocarcinogenic (group 2B), though continues to be used for malaria control in the developing world. While suggested by case reports, anabolic steroids and oral contraceptives have not been shown to increase liver cancer risk in large studies.

Overview of biological mechanisms of human carcinogens

This review summarizes the carcinogenic mechanisms for 109 Group 1 human carcinogens identified as causes of human cancer through Volume 106 of the IARC Monographs. The International Agency for Research on Cancer (IARC) evaluates human, experimental and mechanistic evidence on agents suspected of inducing cancer in humans, using a well-established weight of evidence approach. The monographs provide detailed mechanistic information about all carcinogens. Carcinogens with closely similar mechanisms of action (e.g. agents emitting alpha particles) were combined into groups for the review. A narrative synopsis of the mechanistic profiles for the 86 carcinogens or carcinogen groups is presented, based primarily on information in the IARC monographs, supplemented with a non-systematic review. Most carcinogens included a genotoxic mechanism.

Association between methylation of DNA damage response-related genes and DNA damage in hepatocytes of rats following subchronic exposure to vinyl chloride

In the present study, we investigated the association between methylation of DNA damage response-related genes such as cyclin-dependent kinase inhibitor (CDKN)2A, Ras association (RalGDS/AF-6) domain family member (RASSF)1A, O6-methylguanine DNA methyltransferase (MGMT), Kirsten rat sarcoma viral oncogene homolog (KRAS), and spleen-associated tyrosine kinase (SYK) and DNA damage in hepatocytes of rats following subchronic exposure to vinyl chloride (VC). Sixty-four healthy rats were randomly divided into three VC exposure groups (5, 25, and 125 mg/kg) and an untreated negative control group (n = 16 each). VC was administered by intraperitoneal injection every other day for a total of three times a week. Eight randomly selected rats from each group were sacrificed at the end of 6 and 12 weeks, and liver tissue was harvested for the comet assay and for assessment of DNA methylation level and mRNA expression of related genes by PCR. Overall methylation levels in the genome of hepatocytes in VC-exposed rats were higher than those in the control group at 6 and 12 weeks (P < 0.05), although no differences were observed with regarding to dose (P > 0.05). After 12 weeks of exposure, differences in the methylation of RASSF1A and MGMT promoter regions were observed between the high-dose group and other groups (P < 0.05), whereas no differences were observed for the KRAS, SYK, and CDKN2A promoters (P > 0.05). These results suggest that DNA damage and increased genome-wide methylation are biomarkers for VC exposure and that RASSF1A and MGMT promoter methylation is related to the carcinogenic mechanism of VC.

Molecular and epigenetic markers as promising tools to quantify the effect of occupational exposures and the risk of developing non-communicable diseases

Non-communicable diseases (NCDs) are chronic diseases that are by far the leading cause of death in the world. Many occupational hazards, together with social, economic and demographic factors, have been associated to NCDs development. Genetic susceptibility or environmental exposures alone are not usually sufficient to explain the pathogenesis of NCDs, but can be integrated in a more complex scenario that can result in pathological phenotypes. Epigenetics is a crucial component of this scenario, as its changes are related to specific exposures, therefore potentially able to display the effects of environment on the genome, filling the gap between genetic asset and environment in explaining disease development. To date, the most promising biomarkers have been assessed in occupational cohorts as well as in case/control studies and include DNA methylation, histone modifications, microRNA expression, extracellular vesicles, telomere length, and mitochondrial alterations.

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

BACKGROUND

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

METHODS

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

RESULTS

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

Hepatocellular carcinoma and the risk of occupational exposure

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. The main risk factors for HCC are alcoholism, hepatitis B virus, hepatitis C virus, nonalcoholic steatohepatitis, obesity, type 2 diabetes, cirrhosis, aflatoxin, hemochromatosis, Wilson's disease and hemophilia. Occupational exposure to chemicals is another risk factor for HCC. Often the relationship between occupational risk and HCC is unclear and the reports are fragmented and inconsistent. This review aims to summarize the current knowledge regarding the association of infective and non-infective occupational risk exposure and HCC in order to encourage further research and draw attention to this global occupational public health problem.

Epigenetic alterations induced by genotoxic occupational and environmental human chemical carcinogens: A systematic literature review

Accumulating evidence suggests that epigenetic alterations play an important role in chemically-induced carcinogenesis. Although the epigenome and genome may be equally important in carcinogenicity, the genotoxicity of chemical agents and exposure-related transcriptomic responses have been more thoroughly studied and characterized. To better understand the evidence for epigenetic alterations of human carcinogens, and the potential association with genotoxic endpoints, we conducted a systematic review of published studies of genotoxic carcinogens that reported epigenetic endpoints. Specifically, we searched for publications reporting epigenetic effects for the 28 agents and occupations included in Monograph Volume 100F of the International Agency for the Research on Cancer (IARC) that were classified as "carcinogenic to humans" (Group 1) with strong evidence of genotoxic mechanisms of carcinogenesis. We identified a total of 158 studies that evaluated epigenetic alterations for 12 of these 28 carcinogenic agents and occupations (1,3-butadiene, 4-aminobiphenyl, aflatoxins, benzene, benzidine, benzo[a]pyrene, coke production, formaldehyde, occupational exposure as a painter, sulfur mustard, and vinyl chloride). Aberrant DNA methylation was most commonly studied, followed by altered expression of non-coding RNAs and histone changes (totaling 85, 59 and 25 studies, respectively). For 3 carcinogens (aflatoxins, benzene and benzo[a]pyrene), 10 or more studies reported epigenetic effects. However, epigenetic studies were sparse for the remaining 9 carcinogens; for 4 agents, only 1 or 2 published reports were identified. While further research is needed to better identify carcinogenesis-associated epigenetic perturbations for many potential carcinogens, published reports on specific epigenetic endpoints can be systematically identified and increasingly incorporated in cancer hazard assessments.

Prevalence of K-Ras mutations in hepatocellular carcinoma: A Turkish Oncology Group pilot study

Hepatocellular carcinoma (HCC) is the fifth most common male-predominant type of cancer worldwide. There is no effective treatment regimen available for advanced-stage disease and chemotherapy is generally ineffective in these patients. The number of studies on the prevalence of K-Ras mutations in HCC patients is currently limited. A total of 58 patients from 6 comprehensive cancer centers in 4 metropolitan cities of Turkey were enrolled in this study. Each center committed to enroll approximately 10 random patients whose formalin-fixed paraffin-embedded tumor tissues were available for K-Ras, exon 2 genotyping. Two methods were applied based on the availability of adequate amounts of tumor DNA. In the first method, the samples were processed using TheraScreen. The genomic DNA was further used to detect the 7 most frequent somatic mutations (35G>A; 35G>C; 35G>T; 34G>A; 34G>C; 34G>T and 38G>A) in codons 12 and 13 in exon 2 of the K-Ras oncogene by quantitative polymerase chain reaction (PCR). In the second method, the genomic DNA was amplified by PCR using primers specific for K-Ras exon 2 with the GML SeqFinder Sequencing System's KRAS kit. The identified DNA sequence alterations were confirmed by sequencing both DNA strands in two independent experiments with forward and reverse primers. A total of 40 samples had adequate tumor tissue for the mutation analysis. A total of 33 (82.5%) of the investigated samples harbored no mutations in exon 2. All the mutations were identified via a direct sequencing technique, whereas none were identified by TheraScreen. In conclusion, in our patients, HCC exhibited a remarkably low (<20%) K-Ras mutation rate. Patients harboring K-Ras wild-type tumors may be good candidates for treatment with epidermal growth factor inhibitors, such as cetuximab.

The Ras/MAPK pathway and hepatocarcinoma: pathogenesis and therapeutic implications

BACKGROUND

Hepatocellular carcinoma (HCC) is still a major health problem, often diagnosed at an advanced stage. The multikinase inhibitor sorafenib is to date the sole approved systemic therapy. Several signalling pathways are implicated in tumour development and progression. Among these pathways, the Ras/MAPK pathway is activated in 50-100% of human HCCs and is correlated with a poor prognosis. The aim of this work was to review the main intracellular mechanisms leading to aberrant Ras pathway activation in HCC and the potential therapeutic implications.

MATERIALS AND METHODS

This review is based on the material found on PubMed up to December 2014. 'Ras signaling, Ras dysregulation, Ras inhibition, MAPK pathway, cancer, hepatocarcinoma and liver cancer' alone or in combination were the main terms used for online research.

RESULTS

Multiple mechanisms lead to the deregulation of the Ras pathway in liver cancer. Ras and Raf gene mutations are rare events in human hepatocarcinogenesis in contrast to experimental models in rodents. Downregulation of several Ras/MAPK pathway inhibitors such as GAPs, RASSF proteins, DUSP1, Sprouty and Spred proteins is largely implicated in the aberrant activation of this pathway in the context of wild-type Ras and Raf genes. Epigenetic or post-transcriptional mechanisms lead to the downregulation of these tumour suppressor genes.

CONCLUSION

Ras/MAPK pathway effectors may be considered as potential therapeutic targets in the field of HCC. In particular after the arrival of sorafenib, more Ras/MAPK inhibitors have emerged and are still in preclinical or clinical investigation for HCC therapy.

Mutation analysis of key genes in RAS/RAF and PI3K/PTEN pathways in Chinese patients with hepatocellular carcinoma

The RAS/RAF and PI3K/PTEN signaling pathways play central roles in hepatocarcinogenesis. KRAS, NRAS, HRAS, BRAF, PIK3CA, PIK3R1 and PTEN are key cancer-related genes in the RAS/RAF and PI3K/PTEN signaling pathways. Genetic alterations in these genes often lead to the dysregulation of the two cascades. Little is known regarding the frequency of hotspot mutations in these critical components among Chinese patients with hepatocellular carcinoma (HCC). In the current study, 57 somatic hotspot mutations in 36 HCCs samples collected from Chinese patients using direct DNA sequencing method were examined. Two cases of KRAS somatic mutations (KRAS codon 61; Gln to His) were identified among 36 HCCs (5.6%). However, no mutations were found in the NRAS, HRAS, BRAF, PIK3CA, PIK3R1 and PTEN genes. These findings indicated that point mutations in the KRAS gene, but not mutations in NRAS, HRAS, BRAF, PIK3CA, PIK3R1 and PTEN genes, at a somatic level contribute to the abnormal activation of the RAS/RAF and PI3K/PTEN pathways in HCC.

Primary hepatic angiosarcoma and potential treatment options

Angiosarcomas account for a mere 2-3% of adult soft tissue sarcomas, with an overall poor outcome. Depending on the primary site, angiosarcomas have distinct prognosis. Primary hepatic angiosarcomas (PHAs) are much rare tumors, with worse prognosis compared with other angiosarcomas. PHA is reported to be associated with vinyl chloride, but the majority of patients were still with unknown etiology. As PHA lacks specific symptoms, signs, or images, pathological diagnosis is necessary. The review summarizes 25 articles published from January 2000 to December 2012, including 64 cases of PHA with detailed information. Survival curves are estimated using the Kaplan-Meier method by SPSS 21.0. We find that the median survival time is 5 months; local excision alone or combination with adjuvant therapy is the optimal choice, with median survival time of 17 months. In addition, liver transplant is abandoned for high recurrence rate; emergent transcatheter arterial embolization is thought to be an efficient method for controlling intra-abdominal bleeding; and transcatheter arterial chemoembolization and chemotherapy may be helpful in improving survival.

Aberrant p16INK4A methylation: Relation to viral related chronic liver disease and hepatocellular carcinoma

Background:

Hepatocellular carcinoma (HCC) is currently the fifth most common solid tumor worldwide and the third leading cause of cancer related deaths. Several studies have shown that the tumor suppressor gene p16INK4A is frequently downregulated by aberrant methylation of the 5’-cytosine-phosphoguanine island within the promoter region.

Aim:

To find out the frequency of methylated p16INK4A in the peripheral blood of HCC and cirrhotic patients and to evaluate its role in hepatocarcinogenesis.

Patients and Methods:

This study was performed on 58 subjects: 30 HCC patients, 20 cirrhotic patients, and eight healthy volunteers. Methylation of p16INK4A was examined using methylation specific polymerase chain reaction (PCR) (MSP). Comparison of quantitative variables between the study groups was done using Mann-Whitney U test for independent samples when not normally distributed. For comparing categorical data, Chi-square (χ²) test was performed. Exact test was used instead when the expected frequency was less than 5.

Results:

Methylation of p16INK4A was found in 6.7% of HCC patients, 5% of liver cirrhosis (LC) patients, and none of the healthy volunteers; 66.67% of the p16INK4A-methylated cases (2/3) were positive for anti-hepatitis C virus (HCV) antibodies (one of them had HCC). All HCC cases with aberrant p16INK4A methylation show very high serum alpha fetoprotein (AFP) level (9,080; 30,000 μg/mL). There were no significant associations between the status of p16INK4A methylation and tumor size.

Conclusion:

Hypermethylation of p16INK4A was found to be infrequent among Egyptian patients with HCC.

Inhibition of type 1 17β-hydroxysteroid dehydrogenase impairs the synthesis of 17β-estradiol in endometriosis lesions

CONTEXT

Endometriosis affects 10% of the women before menopause and has important personal, professional, and societal economic burdens. Because current medical treatments are aimed at reducing the symptoms only, novel therapeutic targets should be identified. Endometriosis is estrogen dependent and in some patients the endometriosis tissue is able to produce estrogens in an autocrine/paracrine manner. In a number of patients, this is the consequence of the high local activity of the 17β-hydroxysteroid-dehydrogenases (17β-HSDs), enzymes able to generate active estrogens from precursors with low activity.

OBJECTIVE

The objective of the study was to identify the 17β-HSD(s) responsible for the high local generation of estrogens in endometriosis and test the possibility to inhibit these enzymes for therapeutic purposes.

DESIGN

The expression of different 17β-HSDs involved in the estrogen metabolism was assessed by real-time PCR in eutopic and ectopic tissue from endometriosis patients (n=14). These biopsies had previously confirmed unbalanced local 17β-HSD activity, which caused high estrogen generation. The possibility to block the synthesis of estrogens by one inhibitor specific for type 1 17β-HSD was assessed by HPLC in tissue lysates from endometriosis tissues (n=27).

RESULTS

In all but one of the patients, a high type 1 17β-HSD level is associated with the unbalanced metabolism of estrogens, leading to higher estrogen synthesis in endometriosis than in the endometrium inside the uterus. Inhibition of type 1 17β-HSD restores to various extents, depending on the patient, the correct metabolism. In 19 of 27 patients analyzed (70%), the 17β-HSD type 1 inhibitor decreased the generation of 17β-estradiol by greater than 85%.

CONCLUSIONS

Inhibition of 17β-HSD type 1 can be a potential future treatment option aimed at restoring the correct metabolic balance of estrogens in endometriosis patients with increased local 17β-HSD type 1 enzyme activity.

Deregulation of signalling pathways in prognostic subtypes of hepatocellular carcinoma: novel insights from interspecies comparison

Hepatocellular carcinoma is a frequent and fatal disease. Recent researches on rodent models and human hepatocarcinogenesis contributed to unravel the molecular mechanisms of hepatocellular carcinoma dedifferentiation and progression, and allowed the discovery of several alterations underlying the deregulation of cell cycle and signalling pathways. This review provides an interpretive analysis of the results of these studies. Mounting evidence emphasises the role of up-regulation of RAS/ERK, P13K/AKT, IKK/NF-kB, WNT, TGF-ß, NOTCH, Hedgehog, and Hippo signalling pathways as well as of aberrant proteasomal activity in hepatocarcinogenesis. Signalling deregulation often occurs in preneoplastic stages of rodent and human hepatocarcinogenesis and progressively increases in carcinomas, being most pronounced in more aggressive tumours. Numerous changes in signalling cascades are involved in the deregulation of carbohydrate, lipid, and methionine metabolism, which play a role in the maintenance of the transformed phenotype. Recent studies on the role of microRNAs in signalling deregulation, and on the interplay between signalling pathways led to crucial achievements in the knowledge of the network of signalling cascades, essential for the development of adjuvant therapies of liver cancer. Furthermore, the analysis of the mechanisms involved in signalling deregulation allowed the identification of numerous putative prognostic markers and novel therapeutic targets of specific hepatocellular carcinoma subtypes associated with different biologic and clinical features. This is of prime importance for the selection of patient subgroups that are most likely to obtain clinical benefit and, hence, for successful development of targeted therapies for liver cancer.

Integrated analysis of somatic mutations and focal copy-number changes identifies key genes and pathways in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy. Here, we performed high-resolution copy-number analysis on 125 HCC tumors and whole-exome sequencing on 24 of these tumors. We identified 135 homozygous deletions and 994 somatic mutations of genes with predicted functional consequences. We found new recurrent alterations in four genes (ARID1A, RPS6KA3, NFE2L2 and IRF2) not previously described in HCC. Functional analyses showed tumor suppressor properties for IRF2, whose inactivation, exclusively found in hepatitis B virus (HBV)-related tumors, led to impaired TP53 function. In contrast, inactivation of chromatin remodelers was frequent and predominant in alcohol-related tumors. Moreover, association of mutations in specific genes (RPS6KA3-AXIN1 and NFE2L2-CTNNB1) suggested that Wnt/β-catenin signaling might cooperate in liver carcinogenesis with both oxidative stress metabolism and Ras/mitogen-activated protein kinase (MAPK) pathways. This study provides insight into the somatic mutational landscape in HCC and identifies interactions between mutations in oncogene and tumor suppressor gene mutations related to specific risk factors.

Kras(G12D) and p53 mutation cause primary intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (IHCC) is a primary cancer of the liver with an increasing incidence and poor prognosis. Preclinical studies of the etiology and treatment of this disease are hampered by the relatively small number of available IHCC cell lines or genetically faithful animal models. Here we report the development of a genetically engineered mouse model of IHCC that incorporates two of the most common mutations in human IHCC, activating mutations of Kras (Kras(G12D)) and deletion of p53. Tissue-specific activation of Kras(G12D) alone resulted in the development of invasive IHCC with low penetrance and long latency. Latency was shortened by combining Kras(G12D) activation with heterozygous or homozygous deletion of p53 (mean survival of 56 weeks vs. 19 weeks, respectively), which also resulted in widespread local and distant metastasis. Serial analysis showed that the murine models closely recapitulated the multistage histopathologic progression of the human disease, including the development of stroma-rich tumors and the premalignant biliary lesions, intraductal papillary biliary neoplasms (IPBN), and Von Meyenburg complexes (VMC; also known as biliary hamartomas). These findings establish a new genetically and histopathologically faithful model of IHCC and lend experimental support to the hypothesis that IPBN and VMC are precursors to invasive cancers.

Multivariate analysis of several molecular markers and clinicopathological features in postoperative prognosis of hepatocellular carcinoma

This study was designed to assess the impact of several molecular markers and clinicopathological characteristics on postoperative survival of patients with hepatocellular carcinoma (HCC). Postoperative clinical data of 64 patients with HCC were retrospectively analyzed. K-ras, PIK3CA, and BRAF gene mutations in surgically resected specimens of the 64 patients with HCC were detected by pyrosequencing. H-ras and XB130 protein expression was examined by immunohistochemistry. A Cox proportional hazards regression model was used for univariate and multivariate survival analyses of the clinical and pathological parameters. The mutation rates of K-ras, PIK3CA, and BRAF genes in HCC were found to be 4.69%, 1.56%, and 0%, respectively. Positive expression rate of XB130 and H-ras in HCC was 75.0% and 93.8%, respectively. Univariate analysis revealed that clinicopathological factors impacting postoperative prognosis of patients with HCC include clinical stage, tumor diameter, and postoperative transcatheter arterial embolization therapy for HCC. Meanwhile, multivariate analysis showed that clinical stage (relative risk [RR]: 6.420, P = 0.013) and tumor diameter (RR: 1.498, P = 0.014) were independent factors impacting postoperative survival of patients with HCC. These findings indicate that the clinical stage and tumor diameter are independent risk factors impacting postoperative survival of patients with HCC. Gene mutations of K-ras and PIK3CA and protein expression of XB130 and H-ras are not associated with the postoperative prognosis of patients with HCC.

Signaling networks in human hepatocarcinogenesis--novel aspects and therapeutic options

Hepatocellular carcinoma (HCC) represents one of the most common human malignancies with poor prognosis. Because therapeutic strategies are insufficient for most HCC patients, there is a great need to determine the central molecular mechanisms and pathways in order to derive novel targets for systemic therapy. There is vast evidence that not only the dysregulation of distinct signaling cascades, but also their interactions at different levels, affect tumor cell function. Through these interactions, the effects of pathways can be increased, and even new tumor-supporting qualities acquired that further facilitate HCC progression. Although several approaches for the modulation of these relevant pathways are under development, future therapeutic strategies should take into account that oncogenic stimuli cannot be understood in a monodimensional manner. In order to avoid escape mechanisms during therapy, strategies based on comprehensive knowledge of the interactive regulatory network in hepatocarcinogenesis are necessary.

Strategies for hepatocellular carcinoma therapy and diagnostics: lessons learned from high throughput and profiling approaches

Over the last decade, numerous small and high-dimensional profiling analyses have been performed in human hepatocellular carcinoma (HCC), which address different levels of regulation and modulation. Because comprehensive analyses are lacking, the following review summarizes some of the general results and compares them with insights from other tumor entities. Particular attention is given to the impact of these results on future diagnostic and therapeutic approaches.

Molecular classification of hepatocellular carcinoma anno 2011

Hepatocellular carcinoma has an increasing incidence and high mortality. Treatment options are limited if the disease is not diagnosed in its early stage. The natural course of the disease is aggressive but not always predictable. Molecular profiling is a promising tool for classification in order to optimize prognosis prediction and treatment for an individual patient. In the last decade a large amount of studies has been conducted to better classify hepatocellular carcinomas. The focus of this review is on implications of molecular classification for prognosis and therapeutic decision making in HCC patients. Most studies used microarray technique for genome wide profiling, but other methods to detect genomic changes and microRNA are gaining interest. The whole genome profiling studies identified differences in affected signalling and tried to relate this to prognosis. Some common subgroups were identified, such as the proliferation cluster and the beta-catenin cluster. However, there is still little overlap between most studies. Better study design and bio-informatical analysis might help in this context.

Hepatocellular carcinoma with persistent hepatitis B virus infection shows unusual downregulation of Ras expression and differential response to Ras mediated signaling

BACKGROUND AND AIM

Persistent infection with hepatitis B virus (HBV) is a major etiological risk factor for hepatocellular carcinoma (HCC). The host cellular components involved in the progression of the carcinoma are still unclear. In the present study we aimed to evaluate Ras mediated signaling in hepatocellular carcinoma with persistent HBV infection.

METHODS

To gain insight into the role of Ras mediated signaling in HBV mediated carcinogenesis we evaluated Ras functionality by mutation analysis, reverse transcription-polymerase chain reaction, immunohistochemistry (IHC), Ras-guanosine triphosphate bound functionality assay and Ras-mediated downstream signaling in a cohort of primary HCC tissues positive for HBV-DNA.

RESULTS

Mutation in codon 12 of K-ras appeared to be an uncommon event in the pathogenesis of HCC. We found unusually low levels of Ras expression in HCC compared with those with normal liver and chronic liver disease (cirrhosis and chronic hepatitis). Considerable heterogeneity was found with respect to Ras-mediated signaling events (pRaf, pMAPK and pAKT). The hepatoma cell line (Hep3B) with integrated HBV showed upregulation in expression and activation of Ras and its downstream signaling in comparison to HBV a negative cell line (HepG2). The contrasting result between the cell lines and primary tumors is worthy of note.

CONCLUSIONS

The unusual finding on downregulation of Ras expression in primary HCC tumors in the present study together with tumor heterogeneity with respect to Ras-mediated signaling events prompts a new role of the wild type K-Ras as a possible growth suppressor and a stochastic model for progression of hepatic cancer.

H-ras consensus sequence and mutations in primary hepatocellular carcinomas of lemurs and lorises

The authors have determined a consensus sequence for exons 1 and 2 of H-ras from captive lemurs and lorises and evaluated samples of nonneoplastic liver and hepatocellular carcinomas (HCC) from affected animals for mutations in these exons. Frozen liver samples were collected from 20 animals representing 9 different species with a sex distribution of 10 males and 10 females. A total of 26 liver samples, including 11 normal livers, 9 HCC, and 6 samples from nonneoplastic regions of liver from animals with HCC, were evaluated. This is the first report of the consensus sequence for exons 1 and 2 of H-ras in prosimians, and the authors have determined that it is identical to that of human H-ras and differs only slightly from the chimpanzee sequence. Point mutations were identified in 6 of the 9 HCC samples examined with codons 7, 22, 32, 56, 61, 84, and 96 affected. Two carcinomas had double mutations, and one tumor had triple mutations. One HCC had a mutation in codon 61, which is identical to a recognized affected codon for an H-ras "hot spot" in rodent neoplasia that has also been reported in human tumors. Although not statistically different, metastasis occurred in 5 of 6 HCC with H-ras mutation and only 1 of 3 HCC without mutations. There were 4 silent mutations that did not contain changes in the encoded amino acids, 2 of which were found in nonneoplastic regions of tumor-bearing liver.

Molecular classification of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most frequent tumour derived from the malignant transformation of hepatocytes. It is well established that cancer is a disease of the genome and, as in other types of solid tumours, a large number of genetic and epigenetic alterations are accumulated during the hepatocarcinogenesis process. Recent developments using comprehensive genomic tools have enabled the identification of the molecular diversity in human HCC. Consequently, several molecular classifications have been described using different approaches and important progress has been made particularly with the transcriptomic, genetic, chromosomal, miRNA and methylation profiling. On the whole, all these molecular classifications are related and one of the major determinants of the identified subgroups of tumours are gene mutations found in oncogenes and tumour suppressors. However, the full understanding of the HCC molecular classification requires additional comprehensive studies using both genomic and pathway analyses. Finally, a refinement of the molecular classification of HCC, taking into account the geographical and genetic diversity of the patients, will be essential for an efficient design of the forthcoming personalized clinical treatments.

Interactions of chemical carcinogens and genetic variation in hepatocellular carcinoma

In the etiology of hepatocellular carcinoma (HCC), in addition to hepatitis B virus and hepatitis C virus infections, chemical carcinogens also play important roles. For example, aflatoxin B(1) (AFB(1)) epoxide reacts with guanine in DNA and can lead to genetic changes. In HCC, the tumor suppressor gene p53 codon 249 mutation is associated with AFB(1) exposure and mutations in the K-ras oncogene are related to vinyl chloride exposure. Numerous genetic alterations accumulate during the process of hepatocarcinogenesis. Chemical carcinogen DNA-adduct formation is the basis for these genetic changes and also a molecular marker which reflects exposure level and biological effects. Metabolism of chemical carcinogens, including their activation and detoxification, also plays a key role in chemical hepatocarcinogenesis. Cytochrome p450 enzymes, N-acetyltransferases and glutathione S-transferases are involved in activating and detoxifying chemical carcinogens. These enzymes are polymorphic and genetic variation influences biological response to chemical carcinogens. This genetic variation has been postulated to influence the variability in risk for HCC observed both within and across populations. Ongoing studies seek to fully understand the mechanisms by which genetic variation in response to chemical carcinogens impacts on HCC risk.

MicroRNA involvement in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third cause of cancer-related death worldwide. Curative options for HCC are limited and exclusively available for patients carrying an early stage HCC. In advanced stages, traditional chemotherapy proved to be only marginally effective or even toxic. Thus, the identification of new treatment options is needed. New targets for non-conventional treatment will necessarily take advantage of progresses on the molecular pathogenesis of HCC. MicroRNAs (miRNAs) are a group of tiny RNAs with a fundamental role in the regulation of gene expression. Aberrant expression of several miRNAs was found to be involved in human hepatocarcinogenesis. miRNA expression signatures were correlated with bio-pathological and clinical features of HCC. In some cases, aberrantly expressed miRNAs could be linked to cancer-associated pathways, indicating a direct role in liver tumourigenesis. For example, up-regulation of mir-221 and mir-21 could promote cell cycle progression, reduce cell death and favour angiogenesis and invasion. These findings suggest that miRNAs could become novel molecular targets for HCC treatment. The demonstration of in vivo efficacy and safety of anti-miRNA compounds has opened the way to their use in clinical trials.

A phase II study of lapatinib in patients with advanced biliary tree and hepatocellular cancer

PURPOSE

To evaluate the response to lapatinib, an inhibitor of epidermal growth factor receptors 1 and 2, in patients with advanced bilary tree cancer (BTC) and hepatocellular cancer (HCC).

METHODS

Lapatinib was dosed at 1,500 mg/day orally continuously.

RESULTS

Fifty-seven patients were accrued (BTC 17, HCC 40). Therapy was well tolerated. The response in BTC was 0% and in HCC was 5%. The progression free survival (PFS) for BTC and HCC patients was 1.8 (95% CI: 1.7-5.2) months and 2.3 (95% CI: 1.7-5.6) months. The median survival for BTC and HCC patients was 5.2 (95% CI 3.3-infinity) months and 6.2 (95% CI: 5.1-infinity) months. EGFR genotyping indicated HCC patients with <20 repeats have the lowest PFS. The occurrence of any skin rash significantly prolonged PFS and survival.

CONCLUSIONS

Lapatinib was well-tolerated. There was evidence of activity in HCC, but therapy with lapatinib did not meet the predefined efficacy rate.

Vinyl Chloride—A Classical Industrial Toxicant of New Interest

The carcinogenicity of vinyl chloride in humans was recognized in 1974 based on observations of hepatic angiosarcomas in highly exposed workers. A multiplicity of endpoints has been demonstrated. The primary target organ, the liver, displays differential susceptibilities of hepatocytes and sinusoidal cells, which are modified by factors of age and dose. There is consistency in organotropism between experimental animals and humans. Vinyl chloride is a pluripotent carcinogen, predominantly directed toward hepatic endothelial (sinusoidal) cells, and second toward the parenchymal cells of the liver. The similarity of results between experimental animals and humans is a solid basis of an amalgamation of experimental and epidemiological risk estimates. Vinyl chloride requires metabolic activation for carcinogenicity and mutagenicity, and toxicokinetics are a key to interpret the dose response. Practically the entire initial metabolism of vinyl chloride is oxidative. At higher exposure concentrations this is nonlinear, and metabolic saturation of metabolism in rats is reached at about 250 ppm. This is consistent with the plateau of hepatic angiosarcoma incidence in rat bioassays. Physiologically based pharmacokinetic/toxicokinetic (PBPK) models have been developed and successfully applied within the frame of human cancer risk assessments. The major DNA adduct induced by vinyl chloride (approximately 98% of total adducts in rats), 7-(2-oxoethyl)guanine, is almost devoid of promutagenic activity. The clearly promutagenic "etheno" adducts N2,3-ethenoguanine and 3,N4-ethenocytosine each represent approximately 1% of the vinyl chloride DNA adducts in rats, and 1,N6-ethenoadenine is found at even lower concentrations. Etheno adducts appear to have a long persistence and are repaired by glycosylases. Vinyl chloride represents a human carcinogen for which a series of mechanistic events connects exposure with the carcinogenic outcome. These include (1) metabolic activation (to form chloroethylene oxide), (2) DNA binding of the reactive metabolite (to exocyclic etheno adducts), (3) promutagenicity of these adducts, and (4) effects of such mutations on protooncogenes/tumor suppressor genes at the gene and gene product levels. In rat hepatocytes, a further event is a biomarker response. Cancer prestages (enzyme-altered foci), as quantitative biomarkers, provide a tool to study dose response even within low dose ranges where a carcinogenic risk cannot be seen in cancer bioassays directly. Such biomarker responses support a linear nonthreshold extrapolation for low-dose assessment of carcinogenic risks due to vinyl chloride. Published risk estimates based on different sets of data (animal experiments, epidemiological studies) appear basically consistent, and on this basis an angiosarcoma risk of approximately 3 x 10(-4) has been deduced by extrapolation, for exposure to 1 ppm vinyl chloride over an entire human working lifetime. An important point that should be considered in regulatory standard settings is the presence of a physiological background of those etheno DNA adducts, which are also produced by vinyl chloride. Likely reasons for this background are oxidative stress and lipid peroxidation. In essence, fundamentals of the hepatocarcinogenicity of vinyl chloride appear now well established, providing a solid scientific basis for regulatory activities.

Molecular mechanism underlying the functional loss of cyclindependent kinase inhibitors p16 and p27 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common human cancers, and its incidence is still increasing in many countries. The prognosis of HCC patients remains poor, and identification of useful molecular prognostic markers is required. Many recent studies have shown that functional alterations of cell-cycle regulators can be observed in HCC. Among the various types of cell-cycle regulators, p16 and p27 are frequently inactivated in HCC and are considered to be potent tumor suppressors. p16, a G1-specific cell-cycle inhibitor that prevents the association of cyclindependent kinase (CDK) 4 and CDK6 with cyclin D1, is frequently inactivated in HCC via CpG methylation of its promoter region. p16 may be involved in the early steps of hepatocarcinogenesis, since p16 gene methylation has been detected in subsets of pre-neoplastic liver cirrhosis patients. p27, a negative regulator of the G1-S phase transition through inhibition of the kinase activities of Cdk2/cyclin A and Cdk2/cyclin E complexes, is now considered to be an adverse prognostic factor in HCC. In some cases of HCC with increased cell proliferation, p27 is overexpressed but inactivated by sequestration into cyclin D1-CDK4-containing complexes. Since loss of p16 is closely related to functional inactivation of p27 in HCC, investigating both p16 and p27 may be useful for precise prognostic predictions in individuals with HCC.

Loss of heterozygosity at D8S298 is a predictor for long-term survival of patients with tumor-node-metastasis stage I of hepatocellular carcinoma

PURPOSE

Our previous studies have shown that chromosome 8p deletion correlates with metastasis of hepatocellular carcinoma (HCC). This study was to determine whether 8p deletion could be used in predicting the prognosis of patients with HCC, particularly in those with early stage of HCC.

EXPERIMENTAL DESIGN

A total of 131 patients with tumor-node-metastasis (TNM) stage I of HCC who underwent curative liver resection were enrolled. Loss of heterozygosity (LOH) was examined using 10 microsatellite markers at chromosome 8p, as well as 14 microsatellites at chromosome 1p, 17p, 4q, 13q, and 16q, and their association with 5-year overall survival (OS) and disease-free survival (DFS) of patients was analyzed.

RESULTS

In the entire cohort of patients, the mean LOH frequency at these 24 loci was 43.2%; LOH frequencies at D8S298 and D1S199 were 31.5% and 33.7%, respectively. LOH at D8S298 was associated with a worse 5-year OS (P = 0.008) and DFS (P = 0.038) in patients with TNM stage I of HCC. Likewise, the patients with LOH at D1S199 had a worse 5-year OS (P < 0.001) and DFS (P = 0.014) compared with those without LOH at D1S199. In multivariate analyses, LOH at D8S298 was an independent predictor of decreased DFS (hazard ratio, 0.372; 95% 95% confidence interval, 0.146-0.948; P = 0.038), whereas LOH at D1S199 was an independent predictor of decreased OS (hazard ratio, 0.281; 95% confidence interval, 0.123-0.643; P = 0.003).

CONCLUSIONS

LOH at D8S298 and D1S199 is independently associated with a worse survival in patients with TNM stage I of HCC after curative resection and could serve as novel prognostic predictors for this subgroup of patients.

Genetic diversity of hepatocellular carcinomas and its potential impact on targeted therapies

Hepatocellular carcinoma (HCC) is one of the most frequent solid tumors worldwide and represents the third cause of mortality among deaths from cancer. It has been extensively studied in terms of genetic alteration in the last 10 years and our knowledge has dramatically increased in this field, leading to the definition of different altered pathways in hepatocarcinogenesis. Recently, a comprehensive study of genetic and transcriptomic alterations in a large series of HCC tumors enabled the identification of a six-group molecular-based classification of HCC, defined by a simple 16-gene signature. This classification is closely related to specific alteration of WNT and AKT oncogenic pathways. Together with the analysis of defined oncogenic proteins, such global classifications could be useful in the prediction of future-targeted therapy efficiency.

Genetics of hepatocellular carcinoma

The completely assembled human genome has made it possible for modern medicine to step into an era rich in genetic information and high-throughput genomic analysis. These novel and readily available genetic resources and analytical tools may be the key to unravel the molecular basis of hepatocellular carcinoma (HCC). Moreover, since an efficient treatment for this disease is lacking, further understanding of the genetic background of HCC will be crucial in order to develop new therapies aimed at selected targets. We report on the current status and recent developments in HCC genetics. Special emphasis is given to the genetics and regulation of major signalling pathways involved in HCC such as p53, Wnt-signalling, TGFβ, Ras, and Rb pathways. Furthermore, we describe the influence of chromosomal aberrations as well as of DNA methylation. Finally, we report on the rapidly developing field of genomic expression profiling in HCC, mainly by microarray analysis.

Genetics of hepatocellular tumors

Numerous genetic alterations are accumulated during the process of hepatocarcinogenesis. These genetic alterations can be divided into two groups. The first set of genetic alterations is specific of hepatocellular tumor risk factors. It includes integration of hepatitis B virus (HBV) DNA, R249S TP53 (tumor protein p53) mutation in aflatoxin B1-exposed patients, KRAS mutations related to vinyl chloride exposure, hepatocyte nuclear factor 1alpha (HNF1alpha) mutations associated to hepatocellular adenomas and adenomatosis polyposis coli (APC) germline mutations predisposing to hepatoblastomas. The second set of genetic alterations are etiological nonspecific, it includes recurrent gains and losses of chromosomes, alteration of TP53 gene, activation of WNT/beta-catenin pathway through CTNNB1/beta-catenin and AXIN (axis inhibition protein) mutations, inactivation of retinoblastoma and IGF2R (insulin-like growth factor 2 receptor) pathways through inactivation of RB1 (retinoblastoma 1), P16 and IGF2R. Comprehensive analyses of these genetic alterations have defined two pathways of hepatocarcinogenesis according to the presence or the absence of chromosomal instability. Hepatitis B virus and poorly differentiated tumors are related to chromosome instable tumors associated with frequent TP53 mutations, whereas non-HBV and well-differentiated tumors are related to chromosomal stable samples that are frequently beta-catenin activated. These classifications have clinical relevance as genetic alterations may also be related to prognosis.

Dysregulation of growth factor signaling in human hepatocellular carcinoma

Dysregulation of pleiotropic growth factors, receptors and their downstream signaling pathway components represent a central protumorigenic principle in human hepatocarcinogenesis. Especially the Insulin-like Growth Factor/IGF-1 receptor (IGF/IGF-1R), Hepatocyte Growth Factor (HGF/MET), Wingless (Wnt/beta-catenin/FZD), Transforming Growth Factor alpha/Epidermal Growth Factor receptor (TGFalpha/EGFR) and Transforming Growth Factor beta (TGFbeta/TbetaR) pathways contribute to proliferation, antiapoptosis and invasive behavior of tumor cells. This review focuses on the relevant alterations in these pathways identified in human human hepatocellular carcinomas (HCCs). Resultant functional effects are modulated by multiple cross-talks between the different signaling pathways and additional tumor-relevant factors, such as cyclooxygenase-2 and p53. Several specific strategies are currently under development such as receptor kinase inhibitors, neutralizing antibodies and antagonistic proteins, which may improve the systemic treatment of human HCCs.

Molecular control of liver development

Recent studies using animal models have elucidated a growing number of evolutionarily conserved genes and pathways that control liver development from the embryonic endoderm. It is increasingly clear that the genetic programs active in embryogenesis are often deregulated or reactivated in disease, cancer, and tissue repair. Understanding the molecular control of liver development should impact diagnosis and treatment of pediatric and adult liver diseases and aid in efforts to differentiate liver tissue in vitro for stem cell-based therapies.

Opportunities for targeted therapies in hepatocellular carcinoma

Hepatocellular cancer (HCC) is the fifth most common solid tumor worldwide, accounting for 500,000 new cases annually. Although less common in the United States, HCC is expected to increase in incidence over the next two decades largely because of the prevalence of hepatitis C virus infection. A majority of patients present with advanced disease and are not candidates for liver transplantation, surgical resection, or regional therapy. In 60% to 80% of patients with HCC, treatment is complicated by underlying liver cirrhosis and hepatic dysfunction. Systemic treatments are minimally effective, can have significant toxicity, and have not been shown to improve patient survival. New approaches targeting molecular abnormalities specific to HCC are needed to improve patient outcome. This review summarizes the state of knowledge of those key aspects of the molecular pathogenesis of HCC that may represent rational therapeutic targets in this disease. Relevant preclinical and clinical information on novel compounds directed toward abnormalities in HCC is reviewed.

Alteration of p53 and p21 during hepatocarcinogenesis in tree shrews

AIM: To investigate p53 mutation and p21 expression in hepatocarcinogenesis induced by hepatitis B virus (HBV) and aflatoxin B₁ (AFB₁) in tree shrews, and to reveal the role of these genes in hepatocarcinogenesis.

METHODS: Tree shrews were divided into four groups: group A, those infected with HBV and fed with AFB₁ (n = 39); group B, those infected with HBV alone (n = 28); group C, those fed with AFB₁ alone (n = 29); and group D, normal controls (n = 20). The tree shrews underwent liver biopsies once every 15 wk. Expression of p53 and p21 proteins and genes in the biopsies and tumor tissues of the experimental tree shrews was detected, respectively, by immunohistochemistry, and by Southern blotting and reverse transcription-polymerase chain reaction and sequencing.

RESULTS: The incidence of hepatocellular carcinomas (HCC) was higher in group A (66.7%) than that in group B (3.57%) and C (30%). The time of HCC occurrence was also earlier in group A than that in group C (120.0 ± 16.6 wk vs 153.3 ± 5.8 wk, respectively, P < 0.01). p53 protein was not detected by immunohistochemistry in all groups before the 75^th wk of the experiment. At the 105^th wk, the positive rates fo p53 were 78.6%, 60% and 71.4% in groups A, B and C, respectively, which were significantly higher than that in group D (10%) (all P < 0.05). An abnormal band of p53 gene was observed in groups A and C. The mutation points of p53 gene in tree shrews with HCC were at codons 275, 78 and 13. The nucleotide sequence and amino acid sequence of tree shrew’s wild-type p53 showed 91.7% and 93.4% homologies with those of human p53, respectively. The immunopositivity for p21 was found before HCC development. The incidence of HCC was significantly higher in tree shrews that were positive for p21 than those negative for p21 (80.0% vs 11.0%, P < 0.001). The incidence of HCC in p21 positive animals in group A was significantly higher than those positive for p21 in group C (P < 0.05).

CONCLUSION: A remarkable synergistic effect on HCC development exists between HBV and AFB₁. p53 mutation promotes the development of HCC. HBV and AFB₁ may synergistically induce p53 gene mutation, and stimulate ras gene expression. ras gene is activated at the earlier stage during hepatocarcinogenesis. p21 protein may be an early marker, and the alterations of p53 may be a late event in the development of HCC.

p16INK4A Hypermethylation Is Associated with Hepatitis Virus Infection, Age, and Gender in Hepatocellular Carcinoma

Purpose: The tumor suppressor gene p16INK4A is mainly inactivated by an epigenetic change involving promoter hypermethylation in hepatocarcinogenesis. The possible clinical impact of p16INK4A methylation and the potential risk factors for this epigenetic alteration have not been thoroughly investigated.

Experimental Design: We studied the methylation status and mRNA and protein expression of p16INK4A in 50 hepatocellular carcinomas and corresponding nonneoplastic liver lesions using methylation-specific PCR, reverse transcription-PCR, and immunohistochemical techniques.

Results: p16INK4A hypermethylation was observed in 58% (29 of 50) of the hepatocellular carcinomas and 16% (6 of 38) of the corresponding chronic hepatitis and cirrhosis tissue samples. p16INK4A methylation was significantly associated with mRNA and protein expression (P &lt; 0.001 and P = 0.003, respectively). All of the p16INK4A-methylated tumors were positive for hepatitis B virus or hepatitis C virus markers, but none of the virus-negative tumors exhibited p16INK4A methylation (P = 0.006). The frequency of p16INK4A hypermethylation tended to be higher in hepatitis C virus-related tumors (23 of 32, 72%) than in hepatitis B virus-related tumors (6 of 13, 46%; P = 0.1). Aberrant methylation of p16INK4A was also related significantly to increasing age, female gender, and normal levels of serum PIVKA-II (P = 0.02, 0.04, and 0.04, respectively). No statistically significant difference in survival was observed between patients with p16INK4A hypermethylation and those without.

Conclusions: Our observations suggest that p16INK4A hypermethylation may contribute to hepatocarcinogenesis from an early stage and that multiple risk factors, such as viral infections, age, and gender, may be associated with p16INK4A hypermethylation in hepatocarcinogenesis.

TP53, p14ARF, p16INK4a and H-ras gene molecular analysis in intestinal-type adenocarcinoma of the nasal cavity and paranasal sinuses

Intestinal-type adenocarcinoma (ITAC) of the nasal cavity and paranasal sinuses is an uncommon tumor associated with occupational exposure to dusts of different origin. Few investigations addressed molecular alterations in ITAC mainly focused on TP53, K-ras and H-ras gene mutations. The occurrence of TP53, p14(ARF) and p16(INK4a) deregulation and H-ras mutations was investigated in 21 consecutive and untreated ITACs cases, 17 with known professional exposure. No H-ras mutations were found. In patients with known exposure, cumulative evidence of TP53 or p14(ARF) alterations accounted for 88% and the evidence of p16(INK4a) alterations for 65%, respectively. TP53 mutations were present in 44% of the ITACs, consisted of G:C-->A:T transitions in 86%, and involved the CpG dinucleotides in 50% of the cases. LOH at the locus 17p13 and an uncommon high rate of p53 stabilization were detected in 58% and 59% of the cases, respectively. p14(ARF)and p16(INK4a) promoter methylation accounted for 80% and 67% respectively, and LOH at the locus 9p21 occurred in 45% of the cases. Interestingly, all dust-exposed tumors with p16(INK4a) alterations shared TP53 or p14(ARF) deregulation. The present results show a close association of this occupational tumor with TP53, p14(ARF) and p16(INK4a) gene deregulation. Given the important role that these genes play in cell growth control and apoptosis, the knowledge of ITAC genetic profile may be helpful in selecting more tailored treatments.