Genetic heterogeneity of hepatocellular carcinoma

Genetic Variants in p53 Pathway Genes Affect Survival of Patients with HBV-Related Hepatocellular Carcinoma

Purpose

P53 is a suppressor gene closely related to carcinogenesis. However, the associations between genetic variants in the p53 signaling pathway and prognosis in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) remain unknown. The current study aims to analyze associations between the single nucleotide polymorphisms (SNPs) in p53 pathway-related genes and survival of patients with HBV-HCC.

Methods

We evaluated the associations between 4698 SNPs in 70 genes of the p53 pathway and overall survival (OS) of 866 patients in additive genetic models by using Cox proportional hazards regression analysis. Stepwise multivariable Cox regression analysis was conducted to determine the independent effects of identified SNPs in single-locus analyses. The expression of quantitative trait loci (eQTL) was also analyzed using data from GTEx and 1000 Genomes Project, and functional prediction of SNPs was performed by using RegulomeDB v2.2, 3DSNP v2.0, HaploReg v4.2 and VannoPortal.

Results

We found that two novel SNPs of CD82 rs7925603 A > G and PMAIP1 rs4396625 A > T, were significantly and independently associated with OS [adjusted hazards ratios (HRs) and 95% confidence intervals (CI) were 1.27 (1.10-1.48) and 0.77 (0.66-0.91), respectively; P = 0.001 and = 0.002, respectively] and that the combined risk genotypes of these SNPs showed a significant association with OS in patients with HBV-HCC (P trend < 0.001). Further eQTL analysis in the GTEx dataset showed that the rs7925603 G allele was associated with lower CD82 mRNA expression levels, while the rs4396625 T allele was associated with higher PMAIP1 mRNA expression levels in whole blood cells.

Conclusion

We identified two observed survival-associated SNPs in CD82 and PMAIP1 in the p53 pathway, which influenced HBV-HCC survival possibly through a mechanism of altering mRNA expression. Large studies are warranted to validate our findings.

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

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

Molecular pathogenesis: Connections between viral hepatitis-induced and non-alcoholic steatohepatitis-induced hepatocellular carcinoma

Hepatocellular carcinoma(HCC) is the sixth most common cancer in the world and is usually caused by viral hepatitis (HBV and HCV), alcoholic, and non-alcoholic fatty liver disease(NAFLD). Viral hepatitis accounts for 80% of HCC cases worldwide. In addition, With the increasing incidence of metabolic diseases, NAFLD is now the most common liver disease and a major risk factor for HCC in most developed countries. This review mainly described the specificity and similarity between the pathogenesis of viral hepatitis(HBV and HCV)-induced HCC and NAFLD-induced HCC. In general, viral hepatitis promotes HCC development mainly through specific encoded viral proteins. HBV can also exert its tumor-promoting mechanism by integrating into the host chromosome, while HCV cannot. Viral hepatitis-related HCC and NASH-related HCC differ in terms of genetic factors, and epigenetic modifications (DNA methylation, histone modifications, and microRNA effects). In addition, both of them can lead to HCC progression through abnormal lipid metabolism, persistent inflammatory response, immune and intestinal microbiome dysregulation.

Correlation of molecular alterations with pathological features in hepatocellular carcinoma: Literature review and experience of an Italian center

Hepatocellular carcinoma (HCC) represents the primary carcinoma of the liver and the fourth leading cause of cancer-related deaths. The World Health Organization estimates an increase in cases in the coming years. The risk factors of HCC are multiple, and the incidence in different countries is closely related to the different risk factors to which the population is exposed. The molecular mechanisms that drive HCC tumorigenesis are extremely complex, but understanding this multistep process is essential for the identification of diagnostic, prognostic, and therapeutic markers. The development of multigenic next-generation sequencing panels through the parallel analysis of multiple markers can provide a landscape of the genomic status of the tumor. Considering the literature and our preliminary data based on 36 HCCs, the most frequently altered genes in HCCs are TERT, CTNNB1, and TP53. Over the years, many groups have attempted to classify HCCs on a molecular basis, but a univocal classification has never been achieved. Nevertheless, statistically significant correlations have been found in HCCs between the molecular signature and morphologic features, and this leads us to think that it would be desirable to integrate the approach between anatomic pathology and molecular laboratories.

Authorship Patterns in Cancer Genomics Publications Across Africa

PURPOSE

Authorship is a proxy indicator of research capacity. Understanding the research capacity is imperative for developing population-specific cancer control strategies. This is particularly apropos for African nations, where mortality from cancer is projected to surpass that from infectious disease and the populations are critically under-represented in cancer and genomics studies. Here, we present an analysis and discussion of the patterns of authorship in Africa as they pertain to cancer genomics research across African countries.

METHODS

PubMed metadata of relevant cancer genomics peer-reviewed publications on African populations, published between January 1, 1990, and December 31, 2019, were retrieved and analyzed for patterns of authorship affiliation using R packages, RISmed, and Pubmed.mineR.

RESULTS

The data showed that only 0.016% (n = 375) of cancer publications globally were on cancer genomics of African people. More than 50% of the first and last authors of these publications originated from the North African countries of Tunisia, Morocco, Egypt, and Algeria. South Africa (13.6% and 12.7%) and Nigeria (2.2% and 1.9%) were the Sub-Saharan African countries most represented by first and last authorship positions, respectively. The United States contributed 12.6% of first and last authored papers, and nearly 50% of all African countries had no contributing author for the publications we reviewed.

CONCLUSION

This study highlights and brings awareness to the paucity of cancer genomics research on African populations and by African authors and identifies a need for concerted efforts to encourage and enable more research in Africa, needed for achieving global equity in cancer outcomes.

Synthesis and biological evaluation of novel isoxazole-piperazine hybrids as potential anti-cancer agents with inhibitory effect on liver cancer stem cells

In our effort for the development of novel anticancer therapeutics, a series of isoxazole-piperazine analogues were prepared, and primarily screened for their antiproliferative potential against hepatocellular carcinoma (HCC; Huh7/Mahlavu) and breast (MCF-7) cancer cells. All compounds demonstrated potent to moderate cytotoxicity on all cell lines with IC₅₀ values in the range of 0.09-11.7 μM. Further biological studies with 6a and 13d in HCC cells have shown that both compounds induced G1 or G2/M arrests resulting in apoptotic cell death. Subsequent analysis of proteins involved in cell cycle progression as well as proliferation of HCC cells revealed that 6a and 13d may affect cellular survival pathways differently depending on the mutation profiles of cells (p53 and PTEN), epidermal/mesenchymal characteristics, and activation of cell mechanisms through p53 dependent/independent pathways. Lastly, we have demonstrated the potential anti-stemness properties of these compounds in which the proportion of liver CSCs in Huh7 cells (CD133+/EpCAM+) were significantly reduced by 6a and 13d. Furthermore, both compounds caused a significant reduction in expression of stemness markers, NANOG or OCT4 proteins, in Mahlavu and Huh7 cells, as well as resulted in a decreased sphere formation capacity in Huh7 cells. Together, these novel isoxazole-piperazine derivatives may possess potential as leads for development of effective anti-cancer drugs against HCC cells with stem cell-like properties.

Occult hepatitis B infection and hepatocellular carcinoma: Epidemiology, virology, hepatocarcinogenesis and clinical significance

Occult hepatitis B infection (OBI) refers to a condition where replication-competent HBV DNA is present in the liver, with or without HBV DNA in the blood, in individuals with serum HBsAg negativity assessed by currently available assays. The episomal covalently closed circular DNA (cccDNA) in OBI is in a low replicative state. Viral gene expression is mediated by epigenetic control of HBV transcription, including the HBV CpG island methylation pathway and post-translational modification of cccDNA-bound histone, with a different pattern from patients with chronic HBV infection. The prevalence of OBI varies tremendously across patient populations owing to numerous factors, such as geographic location, assay characteristics, host immune response, coinfection with other viruses, and vaccination status. Apart from the risk of viral reactivation upon immunosuppression and the risk of transmission of HBV, OBI has been implicated in hepatocellular carcinoma (HCC) development in patients with chronic HCV infection, those with cryptogenic or known liver disease, and in patients with HBsAg seroclearance after chronic HBV infection. An increasing number of prospective studies and meta-analyses have reported a higher incidence of HCC in patients with HCV and OBI, as well as more advanced tumour histological grades and earlier age of HCC diagnosis, compared with patients without OBI. The proposed pathogenetic mechanisms of OBI-related HCC include the influence of HBV DNA integration on the hepatocyte cell cycle, the production of pro-oncogenic proteins (HBx protein and mutated surface proteins), and persistent low-grade necroinflammation (contributing to the development of fibrosis and cirrhosis). There remain uncertainties about exactly how, and in what order, these mechanisms drive the development of tumours in patients with OBI.

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

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

DNMT3b/OCT4 expression confers sorafenib resistance and poor prognosis of hepatocellular carcinoma through IL-6/STAT3 regulation

BACKGROUND

The inflammatory cytokine interleukin-6 (IL-6) is critical for the expression of octamer-binding transcription factor 4 (OCT4), which is highly associated with early tumor recurrence and poor prognosis of hepatocellular carcinomas (HCC). DNA methyltransferase (DNMT) family is closely linked with OCT4 expression and drug resistance. However, the underlying mechanism regarding the interplay between DNMTs and IL-6-induced OCT4 expression and the sorafenib resistance of HCC remains largely unclear.

METHODS

HCC tissue samples were used to examine the association between DNMTs/OCT4 expression levels and clinical prognosis. Serum levels of IL-6 were detected using ELISA assays (n = 144). Gain- and loss-of-function experiments were performed in cell lines and mouse xenograft models to determine the underlying mechanism in vitro and in vivo.

RESULTS

We demonstrate that levels of DNA methyltransferase 3 beta (DNMT3b) are significantly correlated with the OCT4 levels in HCC tissues (n = 144), and the OCT4 expression levels are positively associated with the serum IL-6 levels. Higher levels of IL-6, DNMT3b, or OCT4 predicted early HCC recurrence and poor prognosis. We show that IL-6/STAT3 activation increases DNMT3b/1 and OCT4 in HCC. Activated phospho-STAT3 (STAT-Y640F) significantly increased DNMT3b/OCT4, while dominant negative phospho-STAT3 (STAT-Y705F) was suppressive. Inhibiting DNMT3b with RNA interference or nanaomycin A (a selective DNMT3b inhibitor) effectively suppressed the IL-6 or STAT-Y640F-induced increase of DNMT3b-OCT4 and ALDH activity in vitro and in vivo. The fact that OCT4 regulates the DNMT1 expressions were further demonstrated either by OCT4 forced expression or DNMT1 silence. Additionally, the DNMT3b silencing reduced the OCT4 expression in sorafenib-resistant Hep3B cells with or without IL-6 treatment. Notably, targeting DNMT3b with nanaomycin A significantly increased the cell sensitivity to sorafenib, with a synergistic combination index (CI) in sorafenib-resistant Hep3B cells.

CONCLUSIONS

The DNMT3b plays a critical role in the IL-6-mediated OCT4 expression and the drug sensitivity of sorafenib-resistant HCC. The p-STAT3 activation increases the DNMT3b/OCT4 which confers the tumor early recurrence and poor prognosis of HCC patients. Findings from this study highlight the significance of IL-6-DNMT3b-mediated OCT4 expressions in future therapeutic target for patients expressing cancer stemness-related properties or sorafenib resistance in HCC.

Synthesis and cellular bioactivities of novel isoxazole derivatives incorporating an arylpiperazine moiety as anticancer agents

In our endeavour towards the development of effective anticancer therapeutics, a novel series of isoxazole-piperazine hybrids were synthesized and evaluated for their cytotoxic activities against human liver (Huh7 and Mahlavu) and breast (MCF-7) cancer cell lines. Within series, compounds 5l-o showed the most potent cytotoxicity on all cell lines with IC₅₀ values in the range of 0.3–3.7 μM. To explore the mechanistic aspects fundamental to the observed activity, further biological studies with 5m and 5o in liver cancer cells were carried out. We have demonstrated that 5m and 5o induce oxidative stress in PTEN adequate Huh7 and PTEN deficient Mahlavu human liver cancer cells leading to apoptosis and cell cycle arrest at different phases. Further analysis of the proteins involved in apoptosis and cell cycle revealed that 5m and 5o caused an inhibition of cell survival pathway through Akt hyperphosphorylation and apoptosis and cell cycle arrest through p53 protein activation.

Molecular Targets in Hepatocarcinogenesis and Implications for Therapy

Hepatocarcinogenesis comprises of multiple, complex steps that occur after liver injury and usually involve several pathways, including telomere dysfunction, cell cycle, WNT/β-catenin signaling, oxidative stress and mitochondria dysfunction, autophagy, apoptosis, and AKT/mTOR signaling. Following liver injury, gene mutations, accumulation of oxidative stress, and local inflammation lead to cell proliferation, differentiation, apoptosis, and necrosis. The persistence of this vicious cycle in turn leads to further gene mutation and dysregulation of pro- and anti-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, IL-10, IL-12, IL-13, IL-18, and transforming growth factor (TGF)-β, resulting in immune escape by means of the NF-κB and inflammasome signaling pathways. In this review, we summarize studies focusing on the roles of hepatocarcinogenesis and the immune system in liver cancer. In addition, we furnish an overview of recent basic and clinical studies to provide a strong foundation to develop novel anti-carcinogenesis targets for further treatment interventions.

A Glance at Aflatoxin Research in Mozambique

In Mozambique, aflatoxin research started in the 1960's and has been carried through apparently unrelated efforts according to opportunities. However, they can be grouped in two sets: early epidemiological studies and recent agricultural research. Early investigators found a strong correlation between aflatoxin contamination and primary liver cancer. Since then, there have been efforts to examine the extent of contamination, especially in groundnuts and maize. More recent investigations and interventions aimed mostly to reduce the level of contamination, enough to allow such commodities to gain acceptance in the international market. The current status of knowledge is still marginal but the increasing involvement of local authorities, academia, and international organizations seems promising.

Droplet digital PCR detects high rate of TP53 R249S mutants in cell-free DNA of middle African patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is still a major killing malignancy in sub-Saharan Africa. Lifelong intoxication with aflatoxin B1 is considered as one of the primary causes of this situation. The role of aflatoxin in HCC from a given population is commonly estimated through the prevalence of R249S mutation of TP53, a hallmark for previous exposure to the mycotoxin. However, the role of AFB1 is barely known in large part of Africa. We conducted a survey on circulating cell-free DNA from 149 patients with HCC and 213 control subjects with and without liver diseases from Cameroon and Central African Republic using droplet digital PCR technique. We observed a mutation prevalence of 24.8% (n = 37/149) in patients with tumor and 5.6% (n = 12/213) in controls (P = 2.2E-07). Patients with mutations usually displayed significantly increased circulating alpha-fetoprotein (AFP) values, high hepatitis B virus (HBV) DNA loads as well as worsened values of blood cells count. Interestingly, the fraction of droplets positive for R249S was significantly larger in patients with liver cancer (15.3 ± 3.7%) than in controls (0.5 ± 0.3%, P = 7.1E-04). Our survey indicates that AFB1 is instrumental for HCC development in Middle Africa and that droplet digital PCR might be used in the region both to diagnose HCC and to conduct public health surveys on populations at risk of chronic aflatoxin intoxication.

Neuraminidase 1 (NEU1) promotes proliferation and migration as a diagnostic and prognostic biomarker of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the most malignant cancers worldwide, lacking biomarkers for subtyping and the reliable prognostication. Herein, we report a novel biomarker, NEU1 (neuraminidase 1), is up-regulated in most samples of HCC. The diagnostic value of NEU1 was evaluated by ROC, and the AUC (area under curve) reached 0.87 and 0.96 in two independent datasets, respectively. The survival differences of HCC patients with high or low expression of NEU1 were statistically significant, and a significant correlation between NEU1 expression and clinical information including stage, differentiation, AFP and embolus were observed. NEU1 expression, at both the mRNA and protein levels, were also higher in the portal vein tumor thrombus than tumor tissues. We also measured the proliferation and migration ability of two HCC cell lines following NEU1 interference and over-expression. Migration and proliferation rate were increased in NEU1 high expression groups. Moreover, gene expression studies identified pathways significantly associated with NEU1 expression. Among them, all the genes involved in spliceosomepathway were up regulated in NEU1-high group. In summary, our work identified NEU1 as a novel biomarker for both diagnosis and prognosis in HCC, and one of the most altered pathway of NEU1 is spliceosome.

Upregulation of UBE2Q1 via gene copy number gain in hepatocellular carcinoma promotes cancer progression through β-catenin-EGFR-PI3K-Akt-mTOR signaling pathway

Hepatocellular carcinoma (HCC) is the most common type of liver cancer and represents a highly malignant tumor with a poor prognosis. Therapeutic modalities for HCC are limited and generally ineffective. UBE2Q1 is a putative E2 ubiquitin conjugating enzyme, and has been shown to be overexpressed in various types of cancers including HCC. How UBE2Q1 contributes to hepatocarcinogenesis remains unknown. Here, we show that UBE2Q1 is up-regulated in HCC cell lines and in a subset of human HCC tissues. Up-regulation of UBE2Q1 in primary HCC tumors was significantly correlated with shorter overall survival and disease-free survival. Mechanistically, we showed that the frequent up-regulation of UBE2Q1 in HCCs was attributed to the recurrent UBE2Q1 gene copy gain at chromosome 1q21. Functionally, we showed that knockdown of UBE2Q1 reduced HCC cell proliferation, promoted apoptosis via induction of GADD45α, and suppressed orthotopic tumorigenicity both in vitro and in vivo. Inactivation of UBE2Q1 also impeded HCC cell migration and invasion in vitro through regulating EMT process, and suppressed HCC metastasis in vivo. Interestingly, our data revealed a role of UBE2Q1 in the regulation of β-catenin-EGFR-PI3K-Akt-mTOR signaling pathway. Our findings indicate that UBE2Q1 is a candidate oncogene involved in HCC development and progression and therefore a potential therapeutic target in applicable HCC patients.

Frequency and geographic distribution of TERT promoter mutations in primary hepatocellular carcinoma

Primary hepatocellular carcinoma (HCC) mainly develops in subjects chronically infected with hepatitis B (HBV) and C (HCV) viruses through a multistep process characterized by the accumulation of genetic alterations in the human genome. Nucleotide changes in coding regions (i.e. TP53, CTNNB1, ARID1A and ARID2) as well as in non-coding regions (i.e. TERT promoter) are considered cancer drivers for HCC development with variable frequencies in different geographic regions depending on the etiology and environmental factors. Recurrent hot spot mutations in TERT promoter (G > A at-124 bp; G > A at -146 bp), have shown to be common events in many tumor types including HCC and to up regulate the expression of telomerases. We performed a comprehensive review of the literature evaluating the differential distribution of TERT promoter mutations in 1939 primary HCC from four continents. Mutation rates were found higher in Europe (56.6%) and Africa (53.3%) than America (40%) and Asia (42.5%). In addition, HCV-related HCC were more frequently mutated (44.8% in US and 69.7% in Asia) than HBV-related HCC (21.4% in US and 45.5% in Africa). HCC cases associated to factors other than hepatitis viruses are also frequently mutated in TERT promoter (43.6%, 52.6% and 57.7% in USA, Asia and Europe, respectively). These results support a major role for telomere elongation in HCV-related and non-viral related hepatic carcinogenesis and suggest that TERT promoter mutations could represent a candidate biomarker for the early detection of liver cancer in subjects with HCV infection or with metabolic liver diseases.

Impact of country of birth on age at the time of diagnosis of hepatocellular carcinoma in the United States

BACKGROUND

There is global variation in the onset of hepatocellular carcinoma (HCC). The objective of the current study was to investigate the impact of country of birth on age at the time of HCC diagnosis in the United States.

METHODS

Incident HCC cases diagnosed between 2000 and 2012 in the Surveillance, Epidemiology, and End Results program 18 registry were included. Factors associated with very early onset (age at diagnosis < 40 years) and early onset (age at diagnosis < 50 years) were identified by logistic regression.

RESULTS

A total of 59,907 patients were included. The median age at the time of diagnosis of HCC was 62 years and 76% of the patients were male. Of the 75% of patients for whom information regarding birth country was available, 29% were foreign born. In multivariate logistic regression, birth in West Africa (adjusted odds ratio [AOR], 16.3; 95% confidence interval [95% CI], 9.2-27.9 [P<.01]), Central/South/other Africa (AOR, 11.0; 95% CI, 4.5-23.7 [P<.01]), Oceania (AOR, 4.9; 95% CI, 2.9-8.0 [P<.01]), and East Africa (AOR, 3.5; 95% CI, 1.5-6.8 [P<.01]) was found to have the strongest association with very early-onset HCC after adjusting for sex and race/ethnicity. Birth in West Africa, Central/South/other Africa, Oceania, or East Africa also was found to be strongly associated with early-onset HCC.

CONCLUSIONS

Birth country was found to be independently associated with age at the time of HCC diagnosis in the United States. Birth in Africa (except for North Africa) and Oceania was strongly associated with very early-onset HCC. These findings have implications for the design of comprehensive HCC surveillance programs in the United States. Cancer 2016. © 2016 American Cancer Society. Cancer 2017;81-89. © 2016 American Cancer Society.

A novel mutant 10Ala/Arg together with mutant 144Ser/Arg of hepatitis B virus X protein involved in hepatitis B virus-related hepatocarcinogenesis in HepG2 cell lines

Hepatitis B virus (HBV) infection-related hepatocellular carcinoma (HCC) represents a major health problem worldwide. HBV X (HBx) protein is the most common open reading frame that may undergo mutations, resulting in the development of HCC. This study aimed to determine specific HBx mutations that differentiate the central- and para-tumor tissues, and identify their association with HCC development. HBx gene from HCC tumor and para-tumor tissues of 47 HCC patients was amplified, sequenced and statistically analyzed. A novel combination of 2 mutations at residues 10 and 144 was identified which might play a significant role in HCC development. Expression vectors carrying HBx with the specific mutations were constructed and transfected into HepG2 and p53-null HepG2 cells. Compared to wild type (WT) and single mutation of HBx at residue 10 or 144, the 10/144 double mutations strongly up-regulated p21 expression and prolonged G1/S transition in WT- and p53-null HepG2 cells. Apoptosis was also inhibited by HBx harboring 10/44 double-mutation. Binding of 10/144 double-mutant HBx to p53 was lower than WT HBx. Conclusively, the 10/144 double mutation of HBx might play a crucial role in HCC formation.

Common telomerase reverse transcriptase promoter mutations in hepatocellular carcinomas from different geographical locations

AIM: To determine the mutation status of human telomerase reverse transcriptase gene (TERT) promoter region in hepatocellular carcinoma (HCC) from different geographical regions.

METHODS: We analyzed the genomic DNA sequences of 59 HCC samples comprising 15 cell lines and 44 primary tumors, collected from patients living in Asia, Europe and Africa. We amplified a 474 bp DNA fragment of the promoter region of TERT gene including the 1295228 and 1295250 sequence of chromosome 5 by using PCR. Amplicons were then sequenced by Sanger technique and the sequence data were analyzed with by using DNADynamo software in comparison with wild type TERT gene sequence as a reference.

RESULTS: The TERT mutations were found highly frequent in HCC. Eight of the fifteen tested cell lines displayed C228T mutation, and one had C250T mutation with a mutation frequency up to 60%. All of the mutations were heterozygous and mutually exclusive. Ten out of forty-four tumors displayed C228T mutation, and additional five tumors had C250T mutation providing evidence for mutation frequency of 34% in primary tumors. Considering the geographic origins of HCC tumors tested, TERT promoter mutation frequencies were higher in African (53%), when compared to non-African (24%) tumors (P = 0.056). There was also a weak inverse correlation between TERT promoter mutations and murine double minute 2 single nucleotide polymorphism 309 TG polymorphism (P = 0.058). Mutation frequency was nearly two times higher in established HCC cell lines (60%) compared to the primary tumors (34%).

CONCLUSION: TERT promoter is one of most frequent mutational targets in liver cancer, and hepatocellular carcinogenesis is highly associated with the loss of telomere-dependent cellular senescence control.

Hepatitis B virus X protein-induced aberrant epigenetic modifications contributing to human hepatocellular carcinoma pathogenesis

Hepatocellular carcinoma (HCC) remains one of the most prevalent malignant diseases worldwide, and the majority of cases are related to hepatitis B virus (HBV) infection. Interactions between the HBV-encoded X (HBx) protein and host factors are known to play major roles in the onset and progression of HBV-related HCC. These dynamic molecular mechanisms are extremely complex and lead to prominent changes in the host genetic and epigenetic architecture. This review summarizes the current knowledge about HBx-induced epigenetic changes, including aberrations in DNA methylation, histone modifications, and microRNA expression, and their roles in HBV-infected liver cells and HBV-related HCC. Moreover, the HBx-mediated epigenetic control of HBV covalently closed circular DNA (cccDNA) is also discussed. Although this field of study is relatively new, the accumulated evidence has indicated that the epigenetic events induced by HBx play important roles in the development of HBV-related HCC. Ongoing research will help to identify practical applications of the HBV-related epigenetic signatures as biomarkers for early HCC detection or as potential targets to prevent and treat HBV-related HCC.

Transmembrane receptor CXCR7 increases the risk of extrahepatic metastasis of relatively well-differentiated hepatocellular carcinoma through upregulation of osteopontin

Recurrence and metastasis are the main obstacles to improving the survival of patients with post-resective hepato-cellular carcinoma (HCC). Our previous study suggests a critical role of CXCR7 in the metastasis of HCC. In the present study, the effect of CXCR7 as a risk factor for metastasis of HCC was evaluated. Immunohistochemical assay was performed on tissue microarrays based on HCC with extrahepatic metastases after hepatectomy. Two categories based on staining scores were used to evaluate the risk effect of CXCR7, respectively. The effect of CXCR7 on osteopontin (OPN) was explored by RNA interference. Based on the results, in both categories, highly expressed CXCR7 was a dependent risk factor for extrahepatic metastasis because of the potential association with relatively good cell differentiation. Stratification analyses indicated that CXCR7 was a strong independent risk factor (OR, 3.40; 95% CI, 1.07-18.84; P=0.038 in category 1 and OR, 6.40; 95% CI, 1.64-24.92; P=0.007 in category 2, respectively) in patients with Edmondson grade 1/2. Furthermore, CXCR7 correlated well and positively with expression of OPN (P=0.019 and P<0.001 in two categories, respectively) in HCC cases with Edmondson grade 1/2. Immunocytochemistry and RT-PCR demonstrated downregulation of OPN in a highly metastatic HCC cell line following knockdown of CXCR7. Taken together, these findings suggest that high expression of CXCR7 increases the risk of metastasis in post-resective HCC patients with relatively good differentiated tumors, potentially through upregulation of OPN. This group of patients may acquire a survival benefit from early detection and treatment of recurrence and metastasis.

Clinical significance and gene expression study of human hepatic stellate cells in HBV related-hepatocellular carcinoma

BACKGROUND

Peritumoral activated hepatic stellate cells (HSCs) are versatile myofibroblast-like cells closely related with hepatocellular carcinoma (HCC) progression. So far, comprehensive comparison of gene expression of human HSCs during hepatocarcinogenesis is scanty. Therefore, we identified the phenotypic and genomic characteristics of peritumoral HSCs to explore the valuable information on the prognosis and therapeutic targets of HBV related HCC.

METHODS

A tissue microarray containing 224 HBV related HCC patients was used to evaluate the expression of phenotype markers of HSCs including α-SMA, glial fibrillary acidic protein (GFAP), desmin, vinculin and vimentin. HSCs and cancer associated myofibroblasts (CAMFs) were isolated from normal, peritumoral human livers and cancer tissues, respectively. Flow cytometry and gene microarray analysis were performed to evaluate the phenotypic changes and gene expression in HCC, respectively.

RESULTS

Peritumoral α-SMA positive HSCs showed the prognostic value in time to recurrence (TTR) and overall survival (OS) of HCC patients, especially in early recurrence and AFP-normal HCC patients. Expression of GFAP positive HSCs cell lines LX-2 was significantly decreased after stimulation with tumor conditioned medium. Compared with quiescent HSCs, peritumoral HSCs and intratumoral CAMFs expressed considerable up- and down-regulated genes associated with biological process, cellular component, molecular function and signaling pathways involved in fibrogenesis, inflammation and progress of cancer.

CONCLUSIONS

Peritumoral activated HSCs displayed prognostic value in HBV related-HCC, and their genomic characteristics could present rational biomarkers for HCC risk and promising therapeutic targets.

Heterogeneous kinetics of AKT signaling in individual cells are accounted for by variable protein concentration

In most solid cancers, cells harboring oncogenic mutations represent only a sub-fraction of the entire population. Within this sub-fraction the expression level of mutated proteins can vary significantly due to cellular variability limiting the efficiency of targeted therapy. To address the causes of the heterogeneity, we performed a systematic analysis of one of the most frequently mutated pathways in cancer cells, the phosphatidylinositol 3 kinase (PI3K) signaling pathway. Among others PI3K signaling is activated by the hepatocyte growth factor (HGF) that regulates proliferation of hepatocytes during liver regeneration but also fosters tumor cell proliferation. HGF-mediated responses of PI3K signaling were monitored both at the single cell and cell population level in primary mouse hepatocytes and in the hepatoma cell line Hepa1_6. Interestingly, we observed that the HGF-mediated AKT responses at the level of individual cells is rather heterogeneous. However, the overall average behavior of the single cells strongly resembled the dynamics of AKT activation determined at the cell population level. To gain insights into the molecular cause for the observed heterogeneous behavior of individual cells, we employed dynamic mathematical modeling in a stochastic framework. Our analysis demonstrated that intrinsic noise was not sufficient to explain the observed kinetic behavior, but rather the importance of extrinsic noise has to be considered. Thus, distinct from gene expression in the examined signaling pathway fluctuations of the reaction rates has only a minor impact whereas variability in the concentration of the various signaling components even in a clonal cell population is a key determinant for the kinetic behavior.

Modulation of apoptotic signaling by the hepatitis B virus X protein

Worldwide, an estimated 350 million people are chronically infected with the Hepatitis B Virus (HBV); chronic infection with HBV is associated with the development of severe liver diseases including hepatitis and cirrhosis. Individuals who are chronically infected with HBV also have a significantly higher risk of developing hepatocellular carcinoma (HCC) than uninfected individuals. The HBV X protein (HBx) is a key regulatory HBV protein that is important for HBV replication, and likely plays a cofactor role in the development of HCC in chronically HBV-infected individuals. Although some of the functions of HBx that may contribute to the development of HCC have been characterized, many HBx activities, and their putative roles during the development of HBV-associated HCC, remain incompletely understood. HBx is a multifunctional protein that localizes to the cytoplasm, nucleus, and mitochondria of HBV‑infected hepatocytes. HBx regulates numerous cellular signal transduction pathways and transcription factors as well as cell cycle progression and apoptosis. In this review, we will summarize reports in which the impact of HBx expression on cellular apoptotic pathways has been analyzed. Although various effects of HBx on apoptotic pathways have been observed in different model systems, studies of HBx activities in biologically relevant hepatocyte systems have begun to clarify apoptotic effects of HBx and suggest mechanisms that could link HBx modulation of apoptotic pathways to the development of HBV-associated HCC.

Gene signatures derived from a c-MET-driven liver cancer mouse model predict survival of patients with hepatocellular carcinoma

Biomarkers derived from gene expression profiling data may have a high false-positive rate and must be rigorously validated using independent clinical data sets, which are not always available. Although animal model systems could provide alternative data sets to formulate hypotheses and limit the number of signatures to be tested in clinical samples, the predictive power of such an approach is not yet proven. The present study aims to analyze the molecular signatures of liver cancer in a c-MET-transgenic mouse model and investigate its prognostic relevance to human hepatocellular carcinoma (HCC). Tissue samples were obtained from tumor (TU), adjacent non-tumor (AN) and distant normal (DN) liver in Tet-operator regulated (TRE) human c-MET transgenic mice (n = 21) as well as from a Chinese cohort of 272 HBV- and 9 HCV-associated HCC patients. Whole genome microarray expression profiling was conducted in Affymetrix gene expression chips, and prognostic significances of gene expression signatures were evaluated across the two species. Our data revealed parallels between mouse and human liver tumors, including down-regulation of metabolic pathways and up-regulation of cell cycle processes. The mouse tumors were most similar to a subset of patient samples characterized by activation of the Wnt pathway, but distinctive in the p53 pathway signals. Of potential clinical utility, we identified a set of genes that were down regulated in both mouse tumors and human HCC having significant predictive power on overall and disease-free survival, which were highly enriched for metabolic functions. In conclusions, this study provides evidence that a disease model can serve as a possible platform for generating hypotheses to be tested in human tissues and highlights an efficient method for generating biomarker signatures before extensive clinical trials have been initiated.

Chromosome 1q21 amplification and oncogenes in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the most lethal of human malignancies. During human multistep hepatocarcinogenesis, genomic gain represents an important mechanism in the activation of proto-oncogenes. In many circumstances, activated oncogenes hold clinical implications both as prognostic markers and targets for cancer therapeutics. Gain of chromosome 1q copy is one of the most frequently detected alterations in HCC and 1q21 is the most frequent minimal amplifying region (MAR). A better understanding of the physiological and pathophysiological roles of target genes within 1q21 amplicon will significantly improve our knowledge in HCC pathogenesis, and may lead to a much more effective management of HCC bearing amplification of 1q21. Such knowledge has long term implications for the development of new therapeutic strategies for HCC treatment. Our research group and others, focused on the identification and characterization of 1q21 target genes such as JTB, CKS1B, and CHD1L in HCC progression. In this review, we will summarize the current scientific knowledge of known target genes within 1q21 amplicon and the precise oncogenic mechanisms of CHD1L will be discussed in detail.

Mdm2 Snp309 G allele displays high frequency and inverse correlation with somatic P53 mutations in hepatocellular carcinoma

Loss of function of the p53 protein, which may occur through a range of molecular events, is critical in hepatocellular carcinoma (HCC) evolution. MDM2, an oncogene, acts as a major regulator of the p53 protein. A polymorphism in the MDM2 promoter, SNP309 (T/G), has been shown to alter protein expression and may thus play a role in carcinogenesis. MDM2 SNP309 is also associated with HCC. However, the role of SNP309 in hepatocarcinogenesis with respect to TP53 mutations is unknown. In this study, we investigated the distribution of the MDM2 SNP309 genotype and somatic TP53 (the p53 tumor suppressor gene) mutations in 99 human HCC samples from Africa, Europe, China and Japan. Samples exhibited striking geographical differences in their distribution of SNP309 genotypes. The frequency and spectrum of p53 mutations also varied geographically; TP53 mutations were frequent in Africa, where the SNP309 T/T genotype predominated but were rare in Europe and Japan, where the SNP309 G allele was present more frequently. TP53 mutations were detected in 18% (4/22) of SNP309 T/G and G/G and 82% (18/22) of SNP309 T/T genotype holders; this difference was statistically highly significant (P-value=0.0006). Our results indicated that the presence of the SNP309 G allele is inversely associated with the presence of somatic TP53 mutations because they only coincided in 4% of HCC cases. This finding suggests that the SNP309 G allele may functionally replace p53 mutations, and in addition to known etiological factors, may be partly responsible for differential HCC prevalence.

Impact of hepatitis B virus X protein on the DNA damage response during hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is one of the most prevalent and lethal cancers worldwide. The main HCC-associated diseases are chronic infections with hepatitis B virus (HBV) and hepatitis C virus (HCV), and HBV-associated HCC is still prevalent in Asia. Many studies have suggested that HBV X protein (HBX), which is the most common ORF integrated into the host genome, plays a crucial role in hepatocarcinogenesis. However, the accumulated evidence regarding HBX-mediated signaling pathways is not concordant, and it is difficult to understand the mechanistic nature of HBX-associated hepatocarcinogenesis. For example, HBX was reported to inactivate the early responses to DNA damage via p53-dependent and -independent pathways by interacting with several DNA damage-binding proteins and was also reported to sensitize cells to p53-mediated apoptosis via ataxia-telangiectasia and Rad3-related (ATR)-dependent signaling. HBX also interferes with the centrosome replication process, resulting in rearrangement of chromosomes with micronuclei. Moreover, HBX was found to sensitize protein kinases such as Ras/Raf/mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), stress-activated protein kinase/NH2-terminal-Jun kinase (SAPK/JNK), protein kinase B (PKB/Akt), and Janus kinase/STAT (JAK/STAT), indicating that a variety of signaling pathways may be activated by HBX. In this review, we focus on the roles of HBX in DNA damage repair during HCC development, with a view to achieving a better understanding of the significance of HBX in the early steps of hepatocarcinogenesis.

Tumor suppressor protein p53 induces degradation of the oncogenic protein HBx

The progression of hepatocellular carcinoma (HCC) is known to be strongly related to overexpression of hepatitis Bx (HBx) protein and dysfunction of p53. While the inhibition of p53 by HBx is well known, the effect of p53 on HBx function has not been well studied. In this report, we found that p53 affects the stability of HBx protein. Overexpression of p53 protein reduced the level of HBx protein and downregulation of p53 protein by siRNA increased the level of HBx protein in HCC cell lines. This HBx degradation resulted in reduced HBx-mediated oncogenic signaling, such as activation of NF-kappaB and upregulation of cyclin D1. On the other hand, this p53-mediated HBx protein downregulation is impaired by the ablation of p53 nuclear function, which is accomplished by introducing a common feature of HCC, such as the mutation of p53 and endoplasmic reticulum (ER) stress. In addition, this ablation of p53 function increases HBx-mediated oncogenic signaling with a simultaneous increase in the HBx protein level. Our data suggest that p53 dysfunction in HCC can cause an upregulation of the HBx protein level through the stabilizing of HBx protein in HCC. This upregulation may induce the further progression of HCC.

Up-regulation of the expression of costimulatory molecule CD40 in hepatocytes by hepatitis B virus X antigen

Hepatitis B virus (HBV) is a major causative agent of hepatocellular carcinoma (HCC) but the pathogenesis remains poorly understood. To provide novel insights into the pathogenesis of HBV, we examined the expression profile of HBV-positive HepG2.2.15 and -negative HepG2 cells. Genes that were markedly up- or down-regulated in the presence of HBV are involved in signal transduction, apoptosis, transcriptional regulation, protein degradation and oncogenesis. Among the analyzed co-signaling molecules CD40, CD80, CD86, B7-H1, B7-DC, OX40, and B7RP-1, CD40 was the only one up-regulated. Following establishment of stable HepG2 cell lines transfected with HBV genes, we found that HBxAg up-regulated the expression of CD40. We also found that CD40 activation by CD40L could promote the expression of negative co-signaling molecule B7-H1, rather than induce the apoptosis of HepG2HBx cell as expected. These results suggest that CD40 up-regulation by HBxAg may play a facilitating role in the pathogenesis causing HCC.

A novel regulatory event-based gene set analysis method for exploring global functional changes in heterogeneous genomic data sets

BACKGROUND

Analyzing gene expression data by assessing the significance of pre-defined gene sets, rather than individual genes, has become a main approach in microarray data analysis and this has promisingly derive new biological interpretations of microarray data. However, the detection power of conventional gene list or gene set-based approaches is limited on highly heterogeneous samples, such as tumors.

RESULTS

We developed a novel method, the regulatory event-based Gene Set Analysis (eGSA), which considers not only the consistently changed genes but also every gene regulation (event) of each sample to overcome the detection limit. In comparison with conventional methods, eGSA can detect functional changes in heterogeneous samples more precisely and robustly. Furthermore, by utilizing eGSA, we successfully revealed novel functional characteristics and potential mechanisms of very early hepatocellular carcinoma (HCC).

CONCLUSION

Our study creates a novel scheme to directly target the major cellular functional changes in heterogeneous samples. All potential regulatory routines of a functional change can be further analyzed by the regulatory event frequency. We also provide a case study on early HCCs and reveal a novel insight at the initial stage of hepatocarcinogenesis. eGSA therefore accelerates and refines the interpretation of heterogeneous genomic data sets in the absence of gene-phenotype correlations.

The Molecular Diagnosis of Hepatitis B Virus-Associated Hepatocellular Carcinoma

Hepatitis B virus (HBV) infection is the major cause of hepatocellular carcinoma (HCC) worldwide. The pathogenesis of HBV-associated HCC has been studied extensively, and molecular changes during malignant transformation have been identified. It has been proposed that the insertion of HBV DNA into the human genome results in chromosomal instability and inactivation of tumor suppressor genes. Transactivation of oncogenes, inactivation of tumor suppressor genes, and alteration of the cell cycle by HBV proteins are also involved in the progression of hepatocellular carcinogenesis. Traditional clinical examinations of HCC, such as biopsy, computer tomography, ultrasonic imaging, and detection of such biomarkers as a-fetoprotein, are currently the "gold standard" in diagnosis. These tests diagnose HCC only in the late stages of disease. This limitation has greatly reduced the chance of survival of HCC patients. To resolve this problem, new biomarkers that can diagnose HCC in earlier stages are necessary. Based on recent molecular studies of the effects of HBV on cellular transformation, differentially expressed biomarkers of HBV infection have been elucidated. With the analyses of the HBV replication profile, the viral load (HBV DNA levels) of patients, and the viral protein expression, the severity of hepatitis in the preneoplastic stages can be assessed. In the future, with the molecular profiles identified by genomic and proteomic approaches, stage-specific biomarkers should be identified to monitor the progression and prognosis of HCC.

Chromosome instability in human hepatocellular carcinoma depends on p53 status and aflatoxin exposure

Hepatocellular carcinoma (HCC) is a heterogeneous disease triggered by various risk factors and frequently characterized by chromosome instability. This instability is considered to be caused primarily by Hepatitis B virus (HBV), although aflatoxin B1 (AFB1), a potent fungal mutagen is also suspected to influence chromosomal repair. We studied 90 HCCs from Italy, the country with the highest incidence of hepatocellular carcinoma in Europe, 81 samples from France and 52 specimens from Shanghai, in a region where intake of AFB1 via the diet is known to be high. All 223 tumours were characterized for 15 different genomic targets, including allelic loss at 13 chromosome arms and mutations of beta-catenin and p53 genes. Despite disparity in risk-factor distribution, Italian and French cases did not significantly differ for 14 of the 15 targets tested. beta-Catenin and p53 displayed moderate and similar mutation rates (18-29% of cases) in European series. By contrast, tumours from Shanghai were significantly different, with a lower mutation rate for beta-catenin (4% vs. 26%, p<0.0003) and a higher mutation rate for p53 (48% vs. 22%, p<0.0001) when compared with tumours of European origin. The Arg249Ser mutation, hallmark of exposure to AFB1, represented half of the changes in p53 in Shanghai. Furthermore, when stratified for the presence of HBV or p53 mutations, chromosome instability was always higher in Chinese than in European patients. This difference was particularly strong in p53-wildtype tumours (fractional allelic loss, 29.4% vs. 16.7%, p<0.0001). We suggest that AFB1-associated mutagenesis represents a plausible cause for the higher chromosome instability observed in Chinese HCCs, when compared with European primary liver carcinomas.

Different levels of p53 induced either apoptosis or cell cycle arrest in a doxycycline-regulated hepatocellular carcinoma cell line in vitro

Induction of p53 gene expression in cancer cells can lead to both cell cycle arrest and apoptosis. To clarify whether the level of p53 expression determines the apoptotic response of hepatocellular carcinoma (HCC) cells, we assessed the effect of various levels of expression of p53 gene on a p53-deficient HCC cell line, Hep3B, utilizing a doxycycline (Dox)-regulated inducible p53 expression system. Our results showed that apoptosis was induced in HCC cells with high levels of p53 expression. However, lower level of p53 expression induced only cell cycle arrest but not apoptosis. Bax expression was up-regulated following high levels of p53 expression, while bcl-2 expression was not altered by the level of p53 expression. Moreover, p21 expression was observed in both high and low expression of p53. These results suggest the level of p53 expression could determine if the HCC cells would go into cell cycle arrest or apoptosis. Bax may participate, at least in part, in inducing p53-dependent apoptosis and the induction of p21 alone was able to cause cell cycle arrest but not apoptosis.

TP53 mutations and hepatocellular carcinoma: insights into the etiology and pathogenesis of liver cancer

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and the major risk factors include chronic infections with the hepatitis B (HBV) or C (HCV) virus, and exposure to dietary aflatoxin B(1) (AFB(1)) or alcohol consumption. Multiple genetic and epigenetic changes are involved in the molecular pathogenesis of HCC, for example, somatic mutations in the p53 tumor suppressor gene (TP53) and the activation of the WNT signal transduction pathway. AFB(1) frequently induces G:C to T:A transversions at the third base in codon 249 of TP53 and cooperates with HBV in causing p53 mutations in HCC. The detection of TP53 mutant DNA in plasma is a biomarker of both AFB(1) exposure and HCC risk. Chronic infection with HBV and HCV viruses, and oxyradical disorders including hemochromatosis, also generate reactive oxygen/nitrogen species that can both damage DNA and mutate cancer-related genes such as TP53. Certain mutant p53 proteins may exhibit a 'gain of oncogenic function'. The p53 biological network is a key responder to this oxidative and nitrosative stress. Depending on the extent of the DNA damage, p53 regulates the transcription of protective antioxidant genes and with extensive DNA damage, transactivates pro-oxidant genes that contribute to apoptosis. The X gene of HBV (HBx) is the most common open reading frame integrated into the host genome in HCC and the integrated HBx is frequently mutated. Mutant HBx proteins still retain their ability to bind to p53, and attenuate DNA repair and p53-mediated apoptosis. In summary, both viruses and chemicals are implicated in the etiology of TP53 mutations during the molecular pathogenesis of HCC.

Hepatocellular cancer: a guide for the internist

Hepatocellular cancer is the third leading cause of cancer-related deaths worldwide. Its incidence has increased dramatically in the United States because of the spread of hepatitis C virus infection and is expected to increase for the next 2 decades. Hepatitis B virus, hepatitis C virus, and chronic heavy alcohol use leading to cirrhosis of the liver remain the most important causes. The diagnosis of hepatocellular cancer rests on a combination of radiologic, serologic, and histopathologic criteria. Liver transplantation is the only definitive treatment. Resection of the tumor and other percutaneous therapies are more commonly used in practice, because most hepatocellular cancers are detected at an advanced stage. Patients who are at high risk for the development of hepatocellular cancer should be screened with an ultrasound of the liver every 6 months. The prognosis is dependent on both the underlying liver function and the stage at which the tumor is diagnosed. The aim of this review is to familiarize internists in screening, diagnosis, and referral of patients with hepatocellular cancer in an appropriate and timely fashion.

An intracellular antibody can suppress tumorigenicity in hepatitis B virus X-expressing cells

Although the hepatitis B virus X protein (HBx) is thought to play a causative role in the development of hepatocellular carcinoma, it is not yet known whether interfering with HBx function may affect the cellular transformation of HBx-expressing tumor cells. To address this question, we adopted an intracellular antibody fragment expression approach to block the function of HBx. Expression of a single-chain variable fragment (scFv) specific to HBx (designated as H7scFv) inhibited HBx-dependent cellular transactivation. Furthermore, H7scFv suppressed the growth of HBx-expressing tumor cells in both soft agar and nude mice. The suppressive effect of H7scFv on tumorigenicity appeared not to be mediated by inhibition of HBx-induced growth stimulation since the growth rate of these cells was not affected significantly by H7scFv expression. In conclusion, these data suggest that the HBx-dependent transformed phenotype is reversible and that HBx may be a good molecular target for the treatment of HBV-related tumors.

Genetic alterations in cancer knowledge system: analysis of gene mutations in mouse and human liver and lung tumors

Mutational incidence and spectra for genes examined in both human and mouse lung and liver tumors were analyzed using the National Institute of Environmental Health Sciences (NIEHS) Genetic Alterations in Cancer (GAC) knowledge system. GAC is a publicly available, web-based system for evaluating data obtained from peer-reviewed studies of genetic changes in tumors associated with exposure to chemical, physical, or biological agents, as well as spontaneous tumors. In mice, mutations in Kras2 and Hras-1 were the most common events reported for lung and liver tumors, respectively, whether chemically induced or spontaneous. There was a significant difference in Kras2 mutation incidence for spontaneous versus induced mouse lung tumors and in Hras-1 mutation incidence and spectrum for spontaneous versus induced mouse liver tumors. The major gene changes reported for human lung and liver tumors were in KRAS2 (lung only) and TP53. The KRAS2 mutation incidence was similar for spontaneous and asbestos-induced human lung tumors, while the TP53 mutation incidence differed significantly. Aflatoxin B1, hepatitis B virus, hepatitis C virus, and vinyl chloride all caused TP53 mutations in human liver tumors, but the mutation spectrum for each agent differed. The incidence of KRAS2 mutations in human compared to mouse lung tumors differed significantly, as did the incidence of Hras and p53 gene mutations in human compared to mouse liver tumors. Differences observed in the mutation spectra for agent-induced compared to spontaneous tumors and similarities in spectra for structurally similar agents support the concept that mutation spectra can serve as a "fingerprint" of exposure based on chemical structure.

P53 mutations in hepatocellular carcinoma patients in Egypt

The p53 gene plays a major role in hepatocellular carcinoma (HCC). Acquired mutations may provide clues to etiology, as some carcinogenic agents are associated with specific genetic changes in p53. Our aim was to analyze the spectrum of p53 mutations in tumor tissues from subjects with HCC in Egypt, where there is a rising incidence of HCC due to hepatitis C virus (HCV). We collected tumor tissues from 41 subjects with HCC diagnosed at the National Cancer Institute of Cairo University during 2000-2003. Sequence mutations were analyzed by the Affymetrix GeneChip technique. HCV RNA was detected in the sera of 37 subjects (90%). Only one patient had a current HBV infection. A total of 17 of the 41 subjects (41%) had p53 mutations. Thirteen of these were in exon 7, of which 10 were in codon 249, but only 8 of the 10 were the R249S mutation, previously reported to be associated with aflatoxin exposure. The other three exon 7 mutations were found in codons 232, 242 and 248. A total of three mutations were detected in exon 5 codons 133, 144 and 176. One mutation was detected in exon 8 codon 275. Unlike previous studies, this population is characterized by a high prevalence of chronic HCV infection. The presence of the R249S mutation in exon 7 may indicate that these subjects with HCC have been exposed to aflatoxin (AFB1), and further investigation is in progress to measure AFB1-albumin adducts in the sera of these subjects.

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.

Identification of hepatitis B virus X gene mutation in Hong Kong patients with hepatocellular carcinoma

BACKGROUND

Chronic infection by hepatitis B virus (HBV) is the leading cause of hepatocellular carcinoma (HCC) in man. The viral transactivator HBV X (HBx) gene plays a critical role in the molecular pathogenesis of HBV-related HCC.

OBJECTIVES

The aim of this study was to investigate whether there were particular HBx mutations associated with the Chinese Hong Kong patients with HCC.

STUDY DESIGN

We have examined HBx in 113 tumor tissue samples from patients with HCC and 48 serum samples from the same group. In addition, we also examined the expression of HBx protein and the index of apoptotic cell death in tumor tissues of HCC. The entire coding region of HBx gene from the sample was sequenced and aligned with the published HBx gene sequence.

RESULTS AND CONCLUSIONS

We have identified total 54 different types of mutations in HBx gene. HBx mutations occurred in a very high percentage of samples tested. Mutation of HBx was found in 95.2% and 95.3% of the tumor tissue and serum samples, respectively. Most of samples contained more than one type of the mutation. Relative risk analysis indicated that the mutations in 12 sites of tissue HBx and nine sites of serum HBx were highly associated with HCC, suggesting a potential role of these mutants in carcinogenesis. An insert mutation at position 204: Insert 204AGGCCC, was always found to co-exist with point mutations at 260 (G-->A) and 264 (G/C/T-->A). Furthermore, this particular pattern of HBx mutation was most frequently detected. Immunochemical staining of HBx protein revealed that the nuclear localization of HBx protein in hepatocytes of tumor tissues was highly associated with this particular pattern of HBx mutation. In conclusion, HBx mutation occurs frequently in HCC samples tested and a sample usually has multiple types of mutations. A special pattern of insert at 204 and point mutations at 260 and 264 was identified, and it appears to be associated with the nuclear localization of HBx protein. The development of multiple types of mutations in a given sample may contribute to the process of multiple steps in hepatocarcinogenesis.

Integration of hepatitis B virus DNA into chromosomal DNA during acute hepatitis B

AIM: To examine the serum from black African patients with acute hepatitis B to ascertain if integrants of viral DNA can be detected in fragments of cellular DNA leaking from damaged hepatocytes into the circulation.

METHODS: DNA was extracted from the sera of five patients with uncomplicated acute hepatitis B and one with fulminant disease. Two subgenomic PCRs designed to amplify the complete genome of HBV were used and the resulting amplicons were cloned and sequenced.

RESULTS: HBV and chromosomal DNA were amplified from the sera of all the patients. In one patient with uncomplicated disease, HBV DNA was integrated into host chromosome 7 q11.23 in the WBSCR1 gene. The viral DNA comprised 200 nucleotides covering the S and X genes in opposite orientation, with a 1 169 nucleotide deletion. The right virus/host junction was situated at nucleotide 1 774 in the cohesive overlap region of the viral genome, at a preferred topoisomerase I cleavage motif. The chromosomal DNA was not rearranged. The patient made a full recovery and seroconverted to anti-HBs- and anti-HBe-positivity. Neither HBV nor chromosomal DNA could be amplified from his serum at that time.

CONCLUSION: Integration of viral DNA into chromosomal DNA may occur rarely during acute hepatitis B and, with clonal propagation of the integrant, might play a role in hepatocarcinogenesis.

Molecular pathways in hepatocellular carcinoma

Research over the past decade has unraveled important molecular pathways involved in hepatocellular carcinoma (HCC), and several chromosomal and genetic aberrations have been identified to be responsible for initiation of the carcinogenic process. HBx protein and HCV core protein appear to play a pivotal role in hepatocarcinogenesis related to hepatitis B virus and hepatitis C virus, respectively. These viral oncoproteins allow cells to bypass some of the multi-steps in hepatocarcinogenesis, accounting for the etiological role of the two viruses in HCC. Understanding of the molecular pathways of HCC facilitates the development of novel molecular strategies for chemoprevention and therapy of HCC.

Molecular mechanisms in hepatocellular carcinoma development

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world. It usually develops in patients with chronic viral hepatitis, aflatoxin exposure, or excessive alcohol use. Most patients with HCC present with advanced disease and have a poor prognosis. The implementation of antiviral drugs and the availability of a vaccine for hepatitis B should help reduce the incidence of HCC. Considerable effort has now focused on unraveling the molecular pathogenesis of HCC in order to design better treatments, or to prevent the disease altogether. However, so far, the pathogenesis of HCC appears to be quite heterogeneous among patients. In particular, several mechanisms of tumorigenesis seem to be involved, including loss of tumor suppressor gene function, oncogene activation, direct viral effects, DNA methylation, and angiogenesis. It is not clear which events are critical in tumor initiation versus tumor progression. RNA expression arrays and proteomics hold promise to provide further clues about this common and complex cancer.

Mitochondria as Functional Targets of Proteins Coded by Human Tumor Viruses

Molecular analyses of tumor virus-host cell interactions have provided key insights into the genes and pathways involved in neoplastic transformation. Recent studies have revealed that the human tumor viruses Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus (KSHV), human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), and human T-cell leukemia virus type 1 (HTLV-1) express proteins that are targeted to mitochondria. The list of these viral proteins includes BCL-2 homologues (BHRF1 of EBV; KSBCL-2 of KSHV), an inhibitor of apoptosis (IAP) resembling Survivin (KSHV K7), proteins that alter mitochondrial ion permeability and/or membrane potential (HBV HBx, HPV E[wedge]14, HCV p7, and HTLV-1 p13(II)), and K15 of KSHV, a protein with undefined function. Consistent with the central role of mitochondria in energy production, cell death, calcium homeostasis, and redox balance, experimental evidence indicates that these proteins have profound effects on host cell physiology. In particular, the viral BCL-2 homologues BHRF1 and KSBCL-2 inhibit apoptosis triggered by a variety of stimuli. HBx, p7, E1[wedge]4, and p13(II) exert powerful effects on mitochondria either directly due to their channel-forming activity or indirectly through interactions with endogenous channels. Further investigation of these proteins and their interactions with mitochondria will provide important insights into the mechanisms of viral replication and tumorigenesis and could aid in the discovery of new targets for anti-tumor therapy.

Hepatitis C virus infection is a risk factor for tumor recurrence after resection of small hepatocellular carcinomas

Hepatocellular carcinoma (HCC) is closely associated with chronic hepatitis B or C virus (HBV, HCV) infection. Tumor recurrence frequently occurs after surgical resection and may adversely affect the outcome. This study aimed to investigate the effect of viral hepatitis in association with HCC recurrence after resection. A total of 248 patients [HBV in 165, HCV in 44, dual HBV+HCV in 15, and non-B non-C (NBNC) in 24] who underwent curative resection for HCC were included. The cumulative recurrence rate was compared according to the etiology of the underlying hepatitis and was stratified by tumor size and other clinicopathologic parameters. Altogether, 116 patients (47%) had a tumor recurrence within 17 +/- 11 months after resection. No significant difference in recurrence was noted among the four groups of patients (HBV, HCV, HBV+HCV, NBNC) ( p = 0.248). Persistent hepatitis was more common in the HCV group ( p < 0.001) after resection. Among the 157 patients with a small (= 5 cm) tumor, the recurrence rate was significantly higher in the HCV group than in the HBV, HBV+HCV, and NBNC groups ( p = 0.036). Cox multivariate analysis showed that HCV infection [relative risk (RR) 4.4, 95% confidence interval (CI) 1.3-14.8, p = 0.018] and vascular invasion (RR 3.2, 95% CI 1.2-8.9, p = 0.044) were independent predictors of tumor recurrence. Stratified analysis in other parameters did not show significant differences in terms of tumor recurrence among the four virologic groups ( p > 0.1 for all parameters). In conclusion, patients with small HCCs and concurrent HCV infection are at a high risk of tumor recurrence after resection.

Molecular features of non-B, non-C hepatocellular carcinoma: a PCR-array gene expression profiling study

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC) usually develops following chronic liver inflammation caused by hepatitis C or B virus. Through expression profiling in a rare type of HCC, for which the causes are unknown, we sought to find key genes responsible for each step of hepatocarcinogenesis in the absence of viral influence.

METHODS

We used 68 non-B, non-C liver tissues (20 HCC, 17 non-tumor, 31 normal liver) for expression profiling with PCR-array carrying 3072 genes known to be expressed in liver tissues. To select the differentially expressed genes, we performed random permutation testing. A weighted voting classification algorithm was used to confirm the reliability of gene selection. We then compared these genes with the results of previous expression profiling studies.

RESULTS

A total of 220 differentially expressed genes were selected by random permutation tests. The classification accuracies using these genes were 91.8, 92.0 and 100.0% by a leave-one-out cross-validation, an additional PCR-array dataset and a Stanford DNA microarray dataset, respectively. By comparing our results with previous reports on virus-infected HCC, four genes (ALB, A2M, ECHS1 and IGFBP3) were commonly selected in some studies.

CONCLUSIONS

The 220 differentially expressed genes selected by PCR-array are potentially responsible for hepatocarcinogenesis in the absence of viral influence.

Hepatocellular carcinoma: are we making progress?

Hepatocellular carcinoma is a very prevalent malignancy worldwide, with increasing incidence in the United States. Despite many available treatment options, the prognosis remains poor. Surgical resection or liver transplantation still represents the only potentially curative treatments for HCC. Until more effective systemic therapies are available, different localized treatment approaches will continue to be applied in the management of this disease. Although systemic chemotherapy has been disappointing, increased understanding of the tumor biology in HCC coupled with new drug development may lead to newer agents with novel mechanisms of action that are more efficacious. The poor treatment outcome and dismal prognosis make prevention of HCC an important strategy in controlling this aggressive type of malignancy. Vaccine programs for HBV are ongoing. Efforts are underway to develop a vaccine for HCV. Interferon therapy appears to decrease the risk of developing HCC in patients with hepatitis, especially those with HCV. A number of other approaches for decreasing risk in these patients as well as in those with alcoholic-related cirrhosis are currently being evaluated.

Detection of mutant p53 in hepatocellular cancer from Turkey and its correlation with clinicopathologic parameters

The samples of hepatocellular carcinoma from Turkey, a country with a high prevalence of hepatitis B virus and hepatitis C virus, but low dietary exposure to aflatoxin B1, were examined in order to detect the frequency of mutant p53 and its association with clinical and pathological data. Fifty-two samples of hepatocellular cancer from the patients who were diagnosed in our clinic were included in this study. The mutant p53 protein was searched for by specific enzyme-linked immunosorbent assay. Of 52 patients with hepatocellular carcinoma, 26 (50%) had the mutant p53. The incidence of p53 mutation in hepatocellular cancer patients with chronic liver disease due to hepatitis B virus infection was significantly higher than in those with chronic liver disease due to alcohol, indicating that not alcohol but hepatitis B virus, in fact induces the mutations in p53 gene. In addition, it has been shown that the p53 mutation was significantly associated with the diameter of tumor nodule and the degree of cellular differentiation in hepatocellular cancer. The p53 mutation rate found in our study is concordant for a geography where hepatitis B virus and hepatitis C virus are common. Hepatitis B virus and possibly hepatitis C virus, but not alcohol, should be responsible, to a degree, for the mutational change in p53 protein in hepatocellular cancer patients with chronic liver disease. The p53 mutation is a late event in hepatocarcinogenesis because it is related with cellular differentiation and tumor diameter. The specific ELISA can be a useful screening test in future studies to select the patients for gene therapy using wild-type p53.