Hepatic oxidative DNA damage is associated with increased risk for hepatocellular carcinoma in chronic hepatitis C

Role of the diet as a link between oxidative stress and liver diseases

Oxidative stress is caused by an imbalance between the production of reactive oxygen (free radicals) and the body's ability (antioxidant capacity) to readily detoxify the reactive intermediates or easily repair the resulting damage. An adequate diet, characterized by daily intake of foods associated with improvements in the total antioxidant capacity of individuals and reduced incidence of diseases related to oxidation, can modulate the degree of oxidative stress. In fact, diet-derived micronutrients may be direct antioxidants, or are components of antioxidant enzymes, leading to improvement of some indicators of hepatic function. However, although their increased dietary intake might be beneficial, literature data are still controversial. This review summarizes what is known about the effects of diet nutrients on oxidative stress, inflammation and liver function. Moreover, we have analyzed: (1) the main nutritional components involved in the production and/or removal of free radicals; and (2) the role of free radicals in the pathogenesis of several hepatic diseases and related comorbidities.

Oxidative stress and its significant roles in neurodegenerative diseases and cancer

Reactive oxygen and nitrogen species have been implicated in diverse pathophysiological conditions, including inflammation, neurodegenerative diseases and cancer. Accumulating evidence indicates that oxidative damage to biomolecules including lipids, proteins and DNA, contributes to these diseases. Previous studies suggest roles of lipid peroxidation and oxysterols in the development of neurodegenerative diseases and inflammation-related cancer. Our recent studies identifying and characterizing carbonylated proteins reveal oxidative damage to heat shock proteins in neurodegenerative disease models and inflammation-related cancer, suggesting dysfunction in their antioxidative properties. In neurodegenerative diseases, DNA damage may not only play a role in the induction of apoptosis, but also may inhibit cellular division via telomere shortening. Immunohistochemical analyses showed co-localization of oxidative/nitrative DNA lesions and stemness markers in the cells of inflammation-related cancers. Here, we review oxidative stress and its significant roles in neurodegenerative diseases and cancer.

Hepatic oxidative stress in ovariectomized transgenic mice expressing the hepatitis C virus polyprotein is augmented through suppression of adenosine monophosphate-activated protein kinase/proliferator-activated receptor gamma co-activator 1 alpha signaling

AIM

Oxidative stress plays an important role in hepatocarcinogenesis of hepatitis C virus (HCV)-related chronic liver diseases. Despite the evidence of an increased proportion of females among elderly patients with HCV-related hepatocellular carcinoma (HCC), it remains unknown whether HCV augments hepatic oxidative stress in postmenopausal women. The aim of this study was to determine whether oxidative stress was augmented in ovariectomized (OVX) transgenic mice expressing the HCV polyprotein and to investigate its underlying mechanisms.

METHODS

OVX and sham-operated female transgenic mice expressing the HCV polyprotein and non-transgenic littermates were assessed for the production of reactive oxygen species (ROS), expression of inflammatory cytokines and antioxidant potential in the liver.

RESULTS

Compared with OVX non-transgenic mice, OVX transgenic mice showed marked hepatic steatosis and ROS production without increased induction of inflammatory cytokines, but there was no increase in ROS-detoxifying enzymes such as superoxide dismutase 2 and glutathione peroxidase 1. In accordance with these results, OVX transgenic mice showed less activation of peroxisome proliferator-activated receptor-γ co-activator-1α (PGC-1α), which is required for the induction of ROS-detoxifying enzymes, and no activation of adenosine monophosphate-activated protein kinase-α (AMPKα), which regulates the activity of PGC-1α.

CONCLUSION

Our study demonstrated that hepatic oxidative stress was augmented in OVX transgenic mice expressing the HCV polyprotein by attenuation of antioxidant potential through inhibition of AMPK/PGC-1α signaling. These results may account in part for the mechanisms by which HCV-infected women are at high risk for HCC development when some period has passed after menopause.

The role of inflammation and liver cancer

Persistent inflammation is known to promote and exacerbate malignancy. Primary liver cancer, mostly hepatocellular carcinoma (HCC), is a clear example of inflammation-related cancer as more than 90 % of HCCs arise in the context of hepatic injury and inflammation. HCC represents the fifth most common malignancy and the third leading cause of cancer-related death worldwide with about one million new cases diagnosed every year with almost an equal number of deaths. Chronic unresolved inflammation is associated with persistent hepatic injury and concurrent regeneration, leading to sequential development of fibrosis, cirrhosis, and eventually HCC. Irrespective of the intrinsic differences among various etiological factors, a common denominator at the origin of HCC is the perpetuation of a wound-healing response activated by parenchymal cell death and the resulting inflammatory cascade. Hence, the identification of fundamental inflammatory signaling pathways causing transition from chronic liver injury to dysplasia and HCC could depict new predictive biomarkers and targets to identify and treat patients with chronic liver inflammation. This chapter critically discusses the roles of several major cytokines, chemokines, growth factors, transcription factors, and enzymes as well as a distinct network of inflammatory signaling pathways in the development and progression of HCC. It also highlights and analyzes preclinical animal studies showing innovative approaches of targeting inflammatory mediators and signaling by a variety of natural compounds and synthetic agents to achieve effective therapy as well as prevention of hepatic malignancy. Additionally, current limitations and potential challenges associated with the inhibition of inflammatory signaling as well as future directions of research to accelerate clinical development of anti-inflammatory agents to prevent and treat liver cancer are presented.

Hepatic inflammation and progressive liver fibrosis in chronic liver disease

Chronic liver inflammation drives hepatic fibrosis, and current immunosuppressive, anti-inflammatory, and anti-viral therapies can weaken this driver. Hepatic fibrosis is reversed, stabilized, or prevented in 57%-79% of patients by conventional treatment regimens, mainly by their anti-inflammatory actions. Responses, however, are commonly incomplete and inconsistently achieved. The fibrotic mechanisms associated with liver inflammation have been clarified, and anti-fibrotic agents promise to improve outcomes as adjunctive therapies. Hepatitis C virus and immune-mediated responses can activate hepatic stellate cells by increasing oxidative stress within hepatocytes. Angiotensin can be synthesized by activated hepatic stellate cells and promote the production of reactive oxygen species. Anti-oxidants (N-acetylcysteine, S-adenosyl-L-methionine, and vitamin E) and angiotensin inhibitors (losartin) have had anti-fibrotic actions in preliminary human studies, and they may emerge as supplemental therapies. Anti-fibrotic agents presage a new era of supplemental treatment for chronic liver disease.

Iron metabolic disorder in chronic hepatitis C: mechanisms and relevance to hepatocarcinogenesis

The liver is the major iron storage organ in the body, and therefore, iron metabolic disorder is sometimes involved in chronic liver diseases. Chronic hepatitis C is one of the liver diseases that show hepatic iron accumulation, even though its level should be recognized to be basically mild to moderate and sometimes within the normal range. The mechanisms underlying hepatic iron accumulation in chronic hepatitis C have not been fully elucidated. Reduction of the hepcidin transcription activity by hepatitis C virus (HCV)-induced reactive oxygen species may in part account for it, but the regulation of hepcidin is very complex and may depend on many variables, including the particular stage of the systemic and/or hepatic inflammatory conditions and the circulating transferrin-bound iron and intracellular iron stores. This might explain the variations in hepatic iron concentrations reported among patients with HCV-related chronic liver disease. However, even mild-to-moderate iron overload in the liver contributes to disease progression and hepatocarcinogenesis in chronic hepatitis C probably by reinforcing the HCV-induced oxidative stress through Fenton reaction. The present review highlights the current concept of hepatic iron overload status in chronic hepatitis C and discusses how iron metabolic disorder develops in this disease and the impact of hepatic iron overload on disease progression and its relevance to hepatocarcinogenesis.

CD34 expression in noncancerous liver tissue predicts multicentric recurrence of hepatocellular carcinoma

BACKGROUND

Metachronous multicentric recurrence of hepatocellular carcinoma (HCC) is a common cause of morbidity and mortality following curative surgical resection. Clinical and laboratory predictors of these processes can markedly aid in managing these patients. Capillarization of hepatic sinusoids is also a well-known phenomenon in many liver diseases, especially in neoplastic liver diseases. Here, we investigated the clinical features, fibrosis scores and distribution of CD34 in noncancerous hepatic tissues of postresection patients with and without multicentric recurrence.

METHODS

Eighteen patients with multicentric recurrence of HCC diagnosed by histological examination of repeated hepatectomy specimens and 72 HCC patients with more than 5-year disease-free survival postresection participated in the study. We compared the clinicopathological features of these two groups. We examined noncancerous hepatic tissues for iron deposition by Prussian blue staining and computed the CD34-labeling index (LI) through immunohistochemistry using anti-CD34 antibody.

RESULTS

CD34-LI was significantly higher in the multicentric recurrence group (p < 0.001) and staging scores of fibrosis were also significantly higher in the recurrence group (p = 0.035). A high histological activity grade (p = 0.057) and a high alanine aminotransferase level (p = 0.060) were also associated with recurrence. There were no significant differences between the two groups in age, sex, hepatitis B virus surface antigen and anti-hepatitis C virus antibody levels, or grade of iron deposition. On multivariate analysis, high CD34-LI was the only independent risk factor (p = 0.001) for metachronous multicentric recurrence.

CONCLUSION

CD34 expression in the capillaries and sinusoids of noncancerous hepatic tissue is a risk factor for multicentric recurrence of HCC. Histologic assessment of hepatic tissue with CD34 immunohistochemistry might be useful for the prognostic evaluation of HCC patients after surgery.

Serum oxidative-anti-oxidative stress balance is dysregulated in patients with hepatitis C virus-related hepatocellular carcinoma

AIM

Oxidative stress is associated with progression of chronic liver disease (CLD). This association is best established in chronic hepatitis C. However, the anti-oxidative state is not well characterized. The objective of the present study was to investigate the balance of oxidative and anti-oxidative stress in CLD patients.

METHODS

We recruited a study population of 208 patients, including healthy volunteers (HV; n = 15), patients with hepatitis B virus (HBV)-related CLD without or with hepatocellular carcinoma (HBV-non-HCC, n = 25, and HBV-HCC, n = 50, respectively), and patients with hepatitis C virus (HCV)-related CLD without or with HCC (HCV-non-HCC, n = 49, and HCV-HCC, n = 69, respectively). Serum levels of reactive oxygen metabolites (ROM) and anti-oxidative markers (OXY-adsorbent test; OXY) were determined, and the balance of these values was used as the oxidative index. Correlations among ROM, OXY, oxidative index and clinical characteristics were investigated.

RESULTS

Patients with CLD exhibited elevated ROM and oxidative index compared to HV. Among patients with CLD, HCV positive status correlated with increased ROM. In CLD, HCV-HCC patients exhibited the highest ROM levels. Among HCV-related CLD patients, lower OXY correlated with HCC positive status, but was recovered by eradication of HCC. In HCV-HCC, lower OXY correlated with high PT-INR.

CONCLUSION

HCV positive CLD patients displayed higher oxidative stress and HCV-HCC patients displayed lower anti-oxidative state. Anti-oxidative state depression was associated with liver reservoir-related data in HCV-HCC and could be reversed with HCC eradication.

Burden of disease attributable to the Hebei Spirit oil spill in Taean, Korea

OBJECTIVES

We aimed to assess the burden of disease (BOD) of the residents living in contaminated coastal area with oil spill and also analysed the BOD attributable to the oil spill by disease, age, sex and subregion.

DESIGN

Health impact assessment by measuring years lived with disability (YLD) due to an oil spill.

SETTING

A whole population of a community affected by an anthropogenic environmental disaster and secondary health outcome data.

PARTICIPANTS

Based on the health outcome survey including 10 171 individuals (male 4354; female 5817), BOD of 66 473 populations (male 33 441; female 33 032) was measured.

INTERVENTIONS

None. Observational study on the effect of a specific environmental health hazard.

PRIMARY AND SECONDARY OUTCOME MEASURES

Using disability adjusted life year (DALY) method, BOD including physical and mental diseases was measured. For the BOD measurement, excess incidences of illnesses related to oil spill were estimated from the comparison of prevalence of the health outcomes between contaminated areas and reference area without contamination.

RESULTS

YLD attributable to the oil spill were estimated to be 14 724 DALYs (male 7425 DALYs; female 7299 DALYs) for the year 2008. The YLD of mental diseases including post-traumatic stress disorder (PTSD) and depression for men were higher than that for women. The YLD for women was higher in asthma and allergies (rhinitis, dermatitis, conjunctivitis) than that for men. The effects of asthma and allergies were the greatest for people in their 40s, with the burden of mental illness being the greatest for those in their 20s. Proximity to the spill site was associated with increased BOD.

CONCLUSIONS

An oil spill near a coastline can cause substantial adverse health effects. As the health effects of hazardous pollutants from oil spills are long-lasting, close follow-up studies are required to identify chronic health effects.

Branched-chain amino acid supplementation reduces oxidative stress and prolongs survival in rats with advanced liver cirrhosis

Long-term supplementation with branched-chain amino acids (BCAA) is associated with prolonged survival and decreased frequency of development of hepatocellular carcinoma (HCC) in patients with liver cirrhosis. However, the pharmaceutical mechanism underlying this association is still unclear. We investigated whether continuous BCAA supplementation increases survival rate of rats exposed to a fibrogenic agent and influences the iron accumulation, oxidative stress, fibrosis, and gluconeogenesis in the liver. Further, the effects of BCAA on gluconeogenesis in cultured cells were also investigated. A significant improvement in cumulative survival was observed in BCAA-supplemented rats with advanced cirrhosis compared to untreated rats with cirrhosis (P<0.05). The prolonged survival due to BCAA supplementation was associated with reduction of iron contents, reactive oxygen species production and attenuated fibrosis in the liver. In addition, BCAA ameliorated glucose metabolism by forkhead box protein O1 pathway in the liver. BCAA prolongs survival in cirrhotic rats and this was likely the consequences of reduced iron accumulation, oxidative stress and fibrosis and improved glucose metabolism in the liver.

DNA damage sensor γ -H2AX is increased in preneoplastic lesions of hepatocellular carcinoma

Background. Phosphorylated histone H2AX (γ-H2AX) is a potential regulator of DNA repair and is a useful tool for detecting DNA damage. To evaluate the clinical usefulness of γ-H2AX in hepatocellular carcinoma (HCC), we measured the level of γ-H2AX in HCC, dysplastic nodule, and nontumorous liver diseases. Methods. The level of γ-H2AX was measured by immunohistochemistry in fifty-eight HCC, 18 chronic hepatitis, 22 liver cirrhosis, and 19 dysplastic nodules. Appropriate cases were also examined by fluorescence analysis and western blotting. Results. All cases with chronic liver disease showed increased levels of γ-H2AX expression. In 40 (69.9%) of 58 cases with HCC, the labeling index (LI) of γ-H2AX was above 50% and was inversely correlated with the histological grade. Mean γ-H2AX LI was the highest in dysplastic nodule (74.1 ± 22.1%), which was significantly higher than HCC (P < 0.005). Moreover, γ-H2AX was significantly increased in nontumorous tissues of HCC as compared with liver cirrhosis without HCC (62.5 ± 24.7%, from 5.1 to 96.0%, P < 0.005). Conclusions. γ-H2AX was increased in the preneoplastic lesions of HCC and might be a useful biomarker for predicting the risk of HCC.

Alterations in the redox state and liver damage: hints from the EASL Basic School of Hepatology

The importance of a correct balance between oxidative and reductive events has been shown to have a paramount effect on cell function for quite a long time. However, in spite of this body of rapidly growing evidence, the implication of the alteration of the redox state in human disease has been so far much less appreciated. Liver diseases make no exception. Although not fully comprehensive, this article reports what discussed during an EASL Basic School held in 2012 in Trieste, Italy, where the effect of the alteration of the redox state was addressed in different experimental and human models. This translational approach resulted in further stressing the concept that this topic should be expanded in the future not only to better understand how oxidative stress may be linked to a liver damage but also, perhaps more important, how this may be the target for better, more focused treatments. In parallel, understanding how alteration of the redox balance may be associated with liver damage may help define sensitive and ideally early biomarkers of the disorder.

Genetic polymorphism in hOGG1 is associated with triple-negative breast cancer risk in Chinese Han women

8-hydroxy-2'-deoxyguanine (8-OHdG), a typical product of oxidative stress-induced DNA damage, can cause a G-T transversion during DNA replication if it is not removed. Human 8-oxoguanine glycosylase 1 (hOGG1), a key DNA repair gene, recognizes and excises 8-OHdG from damaged DNA accurately; however, a c.977C>G (Ser326Cys) polymorphism in hOGG1 can inhibit the gene's ability to remove 8-OHdG. The aim of present study was to investigate the association between the c.977C>G polymorphism in hOGG1 and the risk of breast cancer in Chinese Han women. We used high-resolution melting and sequencing to analyze the genotypes of 630 patients with sporadic breast cancer patients and 777 healthy controls. We also performed risk-stratified subgroup analyses to determine the association between the c.977C>G polymorphism and other characteristics of breast cancer subgroups. Breast cancer patients and healthy controls did not have significantly different of c.977C/G genotypes (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 0.82-1.49, p = 0.57) and c.977G/G genotypes (OR = 1.34, 95% CI = 0.97-1.84, p = 0.09). However, the c.977G/G genotype was especially prevalent in breast cancer patients who were younger than 55 years (OR = 1.58, 95% CI = 1.05-2.39, p = 0.04), were premenopausal status (OR = 1.87, 95% CI = 1.14-3.06, p = 0.02), had triple-negative disease (OR = 2.14, 95% CI = 1.06-4.29, p = 0.04), or p53-positive disease (OR = 1.56, 95% CI = 1.14-2.12, p = 0.005). These findings suggest that the c.977C>G polymorphism in hOGG1 is associated with an increased risk of breast cancer in Chinese Han women who are younger than 55 years, premenopausal, triple-negative, or p53-positive subgroups.

HCV and oxidative stress in the liver

Hepatitis C virus (HCV) is the etiological agent accounting for chronic liver disease in approximately 2-3% of the population worldwide. HCV infection often leads to liver fibrosis and cirrhosis, various metabolic alterations including steatosis, insulin and interferon resistance or iron overload, and development of hepatocellular carcinoma or non-Hodgkin lymphoma. Multiple molecular mechanisms that trigger the emergence and development of each of these pathogenic processes have been identified so far. One of these involves marked induction of a reactive oxygen species (ROS) in infected cells leading to oxidative stress. To date, markers of oxidative stress were observed both in chronic hepatitis C patients and in various in vitro systems, including replicons or stable cell lines expressing viral proteins. The search for ROS sources in HCV-infected cells revealed several mechanisms of ROS production and thus a number of cellular proteins have become targets for future studies. Furthermore, during last several years it has been shown that HCV modifies antioxidant defense mechanisms. The aim of this review is to summarize the present state of art in the field and to try to predict directions for future studies.

Oxidative damage markers as possible discriminatory biomarkers in breast carcinoma

The study was designed to evaluate the markers of oxidative damage and to establish their diagnostic utility in breast carcinoma patients. Levels of 8-hydroxy-2-deoxyguanosine (8-OH-dG), protein carbonyl (PC), and malondialdehyde (MDA) along with total antioxidant status (TAS) were measured in breast carcinoma patients and controls. Receiver operating characteristic (ROC) analysis was done to study the diagnostic potential of the oxidative damage markers. Significant increases in oxidative damage markers were observed in breast carcinoma patients compared with the normal controls, which were accompanied by significant decrease in TAS. The logistic regression analysis revealed higher levels of oxidative stress marker and reduced level of TAS were significantly associated with breast cancer. ROC curves analysis demonstrates that 8-OHdG and PC are better indicators for distinguishing cancer patients from controls, followed by MDA and TAS. Our results indicate increased oxidative damage is associated with malignancy in breast cancer patients. High accuracy of oxidative stress markers in indicating cancer presence can be used as discriminatory makers for efficient diagnosis.

Evaluation of a novel non-invasive (13) C-glucose breath test for the identification of diabetes mellitus in cirrhotic patients

AIM

  Diabetes mellitus (DM) has been reported to worsen the long-term prognosis of cirrhotic patients, and many studies have reported that DM is an independent risk factor for hepatocellular carcinoma. However, an accurate diagnosis of DM is sometimes difficult in cirrhotic patients. Recently, a novel non-invasive (13) C-glucose breath test has been reported to be useful for diagnosing insulin resistance in non-cirrhotic patients. The aim of this study was to evaluate the efficacy of this tool for the identification of DM in cirrhotic patients.

METHODS

  Thirty eight cirrhotic patients with normal fasting serum glucose and hemoglobin A1c levels underwent the (13) C-glucose breath test and the oral glucose tolerance test. Blood and breath samples were collected at baseline and at 30, 60 and 120 min after ingestion of 100 mg (13) C-labeled glucose and 75 g glucose.

RESULTS

  There was a strong correlation between the change in the concentrations at 2 h for the measured (13) C-glucose breath test (2h-BT) and the 2 h plasma glucose level (r = -0.60, P < 0.0001). In a receiver-operator curve analysis using the 2h-BT, the area under the curve was determined to be 0.88, with a sensitivity and specificity (cut-off value of 3.5‰) of 82% and 85%, respectively, for the detection of DM. Multivariate analysis showed the 2h-BT to be an independent parameter to identify DM.

CONCLUSION

  The (13) C-glucose breath test is a useful tool and has the potential to become a routine outpatient examination for the screening of DM in cirrhotic patients.

Cellular and molecular mechanisms of hepatocellular carcinoma: an update

Hepatocellular carcinoma (HCC) is the most common primary malignant tumor that accounts for ~80 % of all liver cancer cases worldwide. It is a multifactorial disease caused by a variety of risk factors and often develops in the background of underlying cirrhosis. A number of cellular phenomena, such as tumor microenvironment, inflammation, oxidative stress, and hypoxia act in concert with various molecular events to facilitate tumor initiation, progression, and metastasis. The emergence of microRNAs and molecular-targeted therapies adds a new dimension in our efforts to combat this deadly disease. Intense research in this multitude of areas has led to significant progress in our understanding of cellular processes and molecular mechanisms that occur during multistage events that lead to hepatocarcinogenesis. In this review, we discuss the current knowledge of HCC, focusing mainly on advances that have occurred during the past 5 years and on the development of novel therapeutics for liver cancer.

Iron metabolic disorder in chronic hepatitis C: insights from recent evidence

The liver is the major iron storage organ in the body, and therefore iron metabolic disorder is sometimes involved in chronic liver diseases. Chronic hepatitis C is one of the liver diseases that show hepatic iron accumulation. The present review highlights the current concept of hepatic iron overload status in chronic hepatitis C and discusses how iron metabolic disorder develops in this disease, and the impact of hepatic iron overload on disease progression and its relevance to hepatocarcinogenesis. The level of hepatic iron accumulation in chronic hepatitis C should be recognized to be basically mild to moderate and sometimes within the normal range. However, even mild to moderate iron overload in the liver contributes to disease progression and hepatocarcinogenesis in chronic hepatitis C, probably by reinforcing the oxidative stress induced by hepatitis C virus (HCV) protein. The mechanisms by which hepatic iron overload develops in chronic hepatitis C have not been fully elucidated. Reduction of the transcription activity of hepcidin by HCV-induced reactive oxygen species may in part account for it, but the regulation of hepcidin is very complex and may depend on many variables, including the particular stage of the systemic and/or hepatic inflammatory conditions and the circulating transferrin-bound iron and intracellular iron stores. This might explain the variations in hepatic iron concentrations reported among patients with HCV-related chronic liver disease.

Simultaneous progression of oxidative stress, angiogenesis, and cell proliferation in prostate carcinoma

OBJECTIVES

To understand the association between markers of oxidative stress, levels of vascular endothelial growth factor (VEGF), and cell proliferation index in relation to disease progression, clinical stage, and cytologic grade in pathophysiology of prostate carcinoma.

PATIENTS AND METHODS

Case control study comprised of 40 prostate carcinoma patients along with 40 age- and sex-matched healthy subjects as controls. Levels of 8-hydroxy-2-deoxy guanosine, protein carbonyl, and malondialdehyde along with total antioxidant status were measured to study the oxidative stress status in the study subjects. Angiogenesis was evaluated by studying the VEGF level and cell proliferation index.

RESULTS

The levels of markers of oxidative stress along with VEGF and cell proliferation index were found to be significantly higher with significantly decreased levels of antioxidant activity in the study subjects in comparison with healthy controls. The results indicate oxidative stress, angiogenesis, and cell proliferation activity increase progressively with the increase in staging and progression of disease.

CONCLUSIONS

Oxidative stress parameters, angiogenesis, and cell proliferation activity point clearly that with the progression of oxidative stress there is a simultaneous progression of angiogenesis, regulation and control of endothelial cell proliferation in relation to disease progression, clinical stage, and cytologic grade in the pathophysiology of prostate carcinoma.

The FA pathway counteracts oxidative stress through selective protection of antioxidant defense gene promoters

Oxidative stress has been implicated in the pathogenesis of many human diseases including Fanconi anemia (FA), a genetic disorder associated with BM failure and cancer. Here we show that major antioxidant defense genes are down-regulated in FA patients, and that gene down-regulation is selectively associated with increased oxidative DNA damage in the promoters of the antioxidant defense genes. Assessment of promoter activity and DNA damage repair kinetics shows that increased initial damage, rather than a reduced repair rate, contributes to the augmented oxidative DNA damage. Mechanistically, FA proteins act in concert with the chromatin-remodeling factor BRG1 to protect the promoters of antioxidant defense genes from oxidative damage. Specifically, BRG1 binds to the promoters of the antioxidant defense genes at steady state. On challenge with oxidative stress, FA proteins are recruited to promoter DNA, which correlates with significant increase in the binding of BRG1 within promoter regions. In addition, oxidative stress-induced FANCD2 ubiquitination is required for the formation of a FA-BRG1-promoter complex. Taken together, these data identify a role for the FA pathway in cellular antioxidant defense.

Role of nitrative and oxidative DNA damage in inflammation-related carcinogenesis

Chronic inflammation induced by biological, chemical, and physical factors has been found to be associated with the increased risk of cancer in various organs. We revealed that infectious agents including liver fluke, Helicobacter pylori, and human papilloma virus and noninfectious agents such as asbestos fiber induced iNOS-dependent formation of 8-nitroguanine and 8-oxo-7, 8-dihydro-2′-deoxyguanosine (8-oxodG) in cancer tissues and precancerous regions. Our results with the colocalization of phosphorylated ATM and γ-H2AX with 8-oxodG and 8-nitroguanine in inflammation-related cancer tissues suggest that DNA base damage leads to double-stranded breaks. It is interesting from the aspect of genetic instability. We also demonstrated IL-6-modulated iNOS expression via STAT3 and EGFR in Epstein-Barr-virus-associated nasopharyngeal carcinoma and found promoter hypermethylation in several tumor suppressor genes. Such epigenetic alteration may occur by controlling the DNA methylation through IL-6-mediated JAK/STAT3 pathways. Collectively, 8-nitroguanine would be a useful biomarker for predicting the risk of inflammation-related cancers.

Oxidative damage in various tissues of rats exposed to radon

Oxidative damage can be induced by many environmental stressors. 8-Hydroxydeoxyguanosine (8-OHdG) has been used as a biomarker of oxidative DNA damage in both in vitro and in vivo studies. In the present study, Wistar rats were exposed to radon gas at a concentration of 100,000Bq/m(3) for 12 h/d for 30, 60, and 120 d, equivalent to cumulative doses of 60, 120, and 240 working level months (WLM), respectively. Changes in levels of 8-OHdG, reactive oxygen species (ROS), and total antioxidant (T-AOC), as well as expressions of some DNA repair enzymes such as 8-oxoguanine DNA glycosylase (OGG1) and MutT homolog 1 (oxidized purine nucleoside triphosphatase, MTH1), were determined in rat urine, peripheral blood lymphocytes, and lung after exposure to radon. The results revealed an increase in 8-OHdG and ROS levels, a decrease in T-AOC levels, and reduced OGG1 and MTH1 expression levels. The elevated amount of 8-OHdG in urine or lymphocytes was positively correlated with the cumulative exposure dose, whereas OGG1 and MHT1 expression levels in lung were inversely correlated with cumulative exposure dose. These findings indicate that oxidative damage induced by radon may be involved in radon-induced carcinogenesis.

Iron overload in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a major causative agent of chronic liver disease worldwide, but the actual mechanisms responsible for liver injury remain unclear. NAFLD includes a spectrum of clinical entities ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) with possible evolution to cirrhosis and hepatocellular carcinoma. Iron is considered a putative element that interacts with oxygen radicals in inducing liver damage/fibrosis and insulin resistance. The role of hepatic iron in the progression of NASH remains controversial, but in some patients, iron may have a role in the pathogenesis of NASH. Though genetic factors, insulin resistance, dysregulation of iron-regulatory molecules, erythrophagocytosis by Kupffer cells may be responsible for hepatic iron accumulation in NASH, exact mechanisms involved in iron overload remain to be clarified. Iron reduction therapy such as phlebotomy or iron-restricted diet may be promising in patients with NAFLD/NASH to reduce hepatic injury as well as insulin resistance. Larger controlled trials of longer duration are warranted to assess the long-term clinical benefit of phlebotomy and/or iron-restricted diet in NAFLD/NASH.

8-Hydroxy-2'-deoxyguanosine expression predicts hepatocellular carcinoma outcome

Hepatocellular carcinoma (HCC) is characterized by increased oxidative stress and the production of 8-hydroxy-2'-deoxyguanosine (8-OHdG), which is one of the main mutagenic modifications of DNA by oxidative stress. We analyzed the association of 8-OHdG with post-operative survival and revealed that low levels of 8-OHdG are associated with significantly shorter survival time. Moreover, levels of 8-OHdG were associated with HCC characteristics, including tumor size, tumor quantity, clinical staging, Child classification, portal vein thrombosis and ascites. These results suggest that oxidative damage is a useful prognostic marker in HCC when other clinical characteristics are present with 8-OHdG.

Post-challenge hyperglycemia is a significant risk factor for the development of hepatocellular carcinoma in patients with chronic hepatitis C

BACKGROUND

Several epidemiological studies have reported that diabetes mellitus is a risk factor for hepatocellular carcinoma (HCC) in hepatitis C virus (HCV)-positive patients. However, it is unclear whether or not post-challenge hyperglycemia is a risk factor. The purpose of this study was to determine the association between post-challenge hyperglycemia and hepatocarcinogenesis in HCV-positive patients.

METHODS

A total of 203 HCV-RNA-positive subjects (108 males, mean age 54.3 ± 10.8 years; 95 females, mean age 56.6 ± 10.3 years; genotype 1b/2a/2b/3a: 152/38/12/1) who underwent liver biopsy and a 75-g oral glucose tolerance test, and who were treated with interferon (IFN) were enrolled in this study. None of the subjects had been treated with antidiabetic drugs. The subjects underwent ultrasonography and/or computed tomography every 6 months after the end of the IFN therapy.

RESULTS

Thirteen patients, including one patient who achieved a sustained viral response (SVR) with IFN, developed HCC. On multivariate analysis, male sex, age >65 years, excessive alcohol consumption, non-SVR, liver steatosis area >5% in liver specimens, and 120-min post-challenge hyperglycemia were risk factors for the development of HCC. After matching subjects for sex, age, alcohol intake, and response to the IFN therapy, advanced fibrosis stages [hazard ratio (HR) 2.8], liver steatosis (HR 5.4), and 120-min post-challenge hyperglycemia (HR 4.9) were significant risk factors for the development of HCC. Furthermore, after matching for the fibrosis stage, liver steatosis (HR 5.7) and 120-min post-challenge hyperglycemia (HR 6.9) remained as significant factors for HCC development.

CONCLUSION

Post-challenge hyperglycemia is an independent risk factor for HCC in HCV-positive patients.

Body mass index is associated with age-at-onset of HCV-infected hepatocellular carcinoma patients

AIM

To identify factors associated with the age at onset of hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC).

METHODS

Five hundred and fifty-six consecutive patients positive for HCV antibody and treatment-naïve HCC diagnosed between 1995 and 2004 were analyzed. Patients were classified into three groups according to age at HCC onset: < 60 years (n = 79), 60-79 years (n = 439), or ≥ 80 years (n = 38). Differences among groups in terms of sex, body mass index (BMI), lifestyle characteristics, and liver function were assessed. Factors associated with HCC onset in patients < 60 or ≥ 80 years were analyzed by logistic regression analysis.

RESULTS

Significant differences emerged for sex, BMI, degree of smoking and alcohol consumption, mean bilirubin, alanine aminotransferase (ALT), and γ-glutamyl transpeptidase (GGT) levels, prothrombin activity, and platelet counts. The mean BMI values of male patients > 60 years old were lower and mean BMI values of female patients < 60 years old were higher than those of the general Japanese population. BMI > 25 kg/m² [hazard ratio (HR), 1.8, P = 0.045], excessive alcohol consumption (HR, 2.5, P = 0.024), male sex (HR, 3.6, P = 0.002), and GGT levels > 50 IU/L (HR, 2.4, P = 0.014) were independently associated with HCC onset in patients < 60 years. Low ALT level was the only factor associated with HCC onset in patients aged ≥ 80 years.

CONCLUSION

Increased BMI is associated with increased risk for early HCC development in HCV-infected patients. Achieving recommended BMI and reducing alcohol intake could help prevent hepatic carcinogenesis.

Oxidative stress and oxidative damage in chemical carcinogenesis

Reactive oxygen species (ROS) are induced through a variety of endogenous and exogenous sources. Overwhelming of antioxidant and DNA repair mechanisms in the cell by ROS may result in oxidative stress and oxidative damage to the cell. This resulting oxidative stress can damage critical cellular macromolecules and/or modulate gene expression pathways. Cancer induction by chemical and physical agents involves a multi-step process. This process includes multiple molecular and cellular events to transform a normal cell to a malignant neoplastic cell. Oxidative damage resulting from ROS generation can participate in all stages of the cancer process. An association of ROS generation and human cancer induction has been shown. It appears that oxidative stress may both cause as well as modify the cancer process. Recently association between polymorphisms in oxidative DNA repair genes and antioxidant genes (single nucleotide polymorphisms) and human cancer susceptibility has been shown.

Pathological aspects of lipid peroxidation

Lipid peroxidation (LPO) product accumulation in human tissues is a major cause of tissular and cellular dysfunction that plays a major role in ageing and most age-related and oxidative stress-related diseases. The current evidence for the implication of LPO in pathological processes is discussed in this review. New data and literature review are provided evaluating the role of LPO in the pathophysiology of ageing and classically oxidative stress-linked diseases, such as neurodegenerative diseases, diabetes and atherosclerosis (the main cause of cardiovascular complications). Striking evidences implicating LPO in foetal vascular dysfunction occurring in pre-eclampsia, in renal and liver diseases, as well as their role as cause and consequence to cancer development are addressed.

Characteristic expression pattern of oxidative stress in livers with cryptogenic hepatocellular carcinoma

The mechanism responsible for the development of hepatocellular carcinoma (HCC) in the setting of oxidative stress has yet to be clearly defined. We studied the role of oxidative stress in hepatocarcinogenesis in subjects without underlying chronic viral hepatitis. The subjects were 24 patients negative for serum hepatitis B surface antigen and hepatitis C antibody tests, who underwent hepatic resection for HCC (Group N). Subjects were excluded if diagnosed with liver disease predisposing to HCC. Immunohistochemical staining for oxidative stress-related markers was performed on non-cancerous liver regions. Resected liver tissues adjacent to HCC from 24 patients with chronic hepatitis B (Group B) and 21 patients with chronic hepatitis C (Group C) were also examined. The percentage of 8-hydroxydeoxyguanosine-positive hepatocytes in Group N was significantly lower than that in Group B and that in the combined population of Groups B and C. The percentage of the area positive for 4-hydroxynonenal in Group N was significantly higher than that in Groups B or C. Meanwhile, the percentage of the area positive for manganese superoxide dismutase in Group N was not different from that in Groups B and C. In conclusion, the mechanism of hepatocarcinogenesis through oxidative stress for patients without known liver disease predisposing to HCC may differ from that for patients with chronic viral hepatitis.

Impact of amino acid substitutions in the hepatitis C virus genotype 1b core region on liver steatosis and hepatic oxidative stress in patients with chronic hepatitis C

BACKGROUND

Liver steatosis and hepatic oxidative stress are the histopathological features of chronic hepatitis C. Hepatitis C virus (HCV) genotype 1 core protein induces hepatic steatosis and reactive oxygen species production in transgenic mice. The amino acid substitutions in the HCV core region appear to be related to hepatocarcinogenesis.

AIMS

The aim of this study was to clarify the impact of mutations in the HCV core region on oxidative stress and lipid metabolism in patients with chronic hepatitis C.

METHODS

Sixty-seven patients (35 men, 32 women; mean age, 58.4 +/- 10.2 years) with chronic hepatitis C with high titres (>5 log IU/ml) were enrolled. Substitutions in amino acids 70, 75 and 91 of the HCV genotype 1b core region, the percentage of hepatic steatosis, and hepatic 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were investigated in all patients. Urinary 8-OHdG levels were measured in 35 patients.

RESULTS

Body mass index, alanine aminotransferase, gamma-glutamyl transferase, and triglyceride levels and substitutions of amino acid 70/Q (glutamine) were significantly associated with the presence of steatosis on univariate analysis. Multivariate analysis showed that substitution of amino acid 70 of glutamine and triglyceride levels were the independent factors related to liver steatosis. Hepatic and urinary 8-OHdG levels were significantly higher in patients with methionine at amino acid 91 of the HCV core region than in those with leucine.

CONCLUSION

Substitutions in the amino acids of the HCV genotype1b core region are associated with hepatic steatosis and oxidative stress in patients with chronic hepatitis C.

Current status of oxidative stress in pediatric liver transplantation

Generation of free radicals in children after liver transplantation is multifactorial from ischemia-reperfusion injury, immunosuppression and post-transplant complications. Thus, this group is at higher risk of oxidative imbalance with molecular and clinical consequences. We discuss pathogenesis and ways of action against oxidative stress in liver transplant recipients.

The role of iron in the pathophysiology and treatment of chronic hepatitis C

Increased hepatic iron content may be observed in patients with chronic hepatitis C infection, and may contribute to disease severity. The presence of hemochromatosis gene mutations is associated with increased hepatic iron accumulation and may lead to accelerated disease progression. Hepatic iron depletion has been postulated to decrease the risk of hepatocellular carcinoma in patients with cirrhosis due to chronic hepatitis C. It is possible that iron depletion stabilizes or improves liver histology and slows disease progression in these individuals. The present article reviews the prevalence and risk factors for hepatic iron overload in chronic hepatitis C, with emphasis on the available data regarding the efficacy of iron depletion in the treatment of this common liver disease.

The role of iron in the pathophysiology and treatment of chronic hepatitis C

Increased hepatic iron content may be observed in patients with chronic hepatitis C infection, and may contribute to disease severity. The presence of hemochromatosis gene mutations is associated with increased hepatic iron accumulation and may lead to accelerated disease progression. Hepatic iron depletion has been postulated to decrease the risk of hepatocellular carcinoma in patients with cirrhosis due to chronic hepatitis C. It is possible that iron depletion stabilizes or improves liver histology and slows disease progression in these individuals. The present article reviews the prevalence and risk factors for hepatic iron overload in chronic hepatitis C, with emphasis on the available data regarding the efficacy of iron depletion in the treatment of this common liver disease.

Oxidative stress and oxidative damage in carcinogenesis

Carcinogenesis is a multistep process involving mutation and the subsequent selective clonal expansion of the mutated cell. Chemical and physical agents including those that induce reative oxygen species can induce and/or modulate this multistep process. Several modes of action by which carcinogens induce cancer have been identified, including through production of reactive oxygen species (ROS). Oxidative damage to cellular macromolecules can arise through overproduction of ROS and faulty antioxidant and/or DNA repair mechanisms. In addition, ROS can stimulate signal transduction pathways and lead to activation of key transcription factors such as Nrf2 and NF-kappaB. The resultant altered gene expression patterns evoked by ROS contribute to the carcinogenesis process. Recent evidence demonstrates an association between a number of single nucleotide polymorphisms (SNPs) in oxidative DNA repair genes and antioxidant genes with human cancer susceptibility. These aspects of ROS biology will be discussed in the context of their relationship to carcinogenesis.

Large cell change of hepatocytes in chronic viral hepatitis represents a senescent-related lesion

Large cell change involves the clustering of hepatocytes with hyperchromatism and cellular enlargement without an increase in the nuclear/cytoplasmic ratio. This study investigated whether large cell change in chronic viral hepatitis reflects cellular senescence because of morphological similarities between the 2 conditions. The expression of markers of senescence such as senescence-associated beta-galactosidase, senescence-associated heterochromatic foci, and p21, as well as markers of cell kinetics such as Ki-67, was examined in 26 frozen and 82 formalin-fixed liver specimens. Large cell change was frequently detected in chronic hepatitis B cases with advanced histologic staging, particularly those with hepatocellular carcinoma. Senescence-associated beta-galactosidase activity, senescence-associated heterochromatic foci, and p21 were frequently detected in areas of large cell change. Hepatocytes with large cell change showed no proliferative or apoptotic activity. The frequent expression of senescent features and the absence of proliferative or apoptotic activity suggest that large cell change represents senescence. The parallel increase in large cell change and hepatocellular carcinoma in chronic hepatitis B raises the possibility that cellular senescence develops as a safeguard against malignant transformation rather than as a precursor of hepatocellular carcinoma.

Diabetes pattern on the 75 g oral glucose tolerance test is a risk factor for hepatocellular carcinoma in patients with hepatitis C virus

BACKGROUND

Patients with hepatitis C virus (HCV) frequently show glucose intolerance. Diabetes mellitus (DM) has been proposed to be a risk factor for hepatocellular carcinoma (HCC).

AIMS

The aim of this study is to clarify the influence of glucose intolerance as evaluated by the 75 g oral glucose tolerance test (OGTT) on hepatocarcinogenesis in patients with HCV.

METHODS

This study was carried out in a cohort of 197 patients with HCV who had not been previously diagnosed as having DM. All patients underwent the 75 g OGTT at entry. They were also screened for HCC and, thereafter, the rate of hepatocarcinogenesis was compared between the patients with and without glucose intolerance.

RESULTS

Based on the results of the 75 g OGTT, 125 (63%) had normal glucose tolerance (NGT), 49 (25%) had impaired glucose tolerance (IGT) and 23 (12%) had the DM pattern. HCC occurred more frequently in patients with the DM pattern than in patients with either NGT or IGT. Even in patients without advanced liver fibrosis, HCC was more frequently observed in patients with DM than in patients with NGT. A multiple logistic regression analysis showed advanced liver fibrosis, the DM pattern on the 75 g OGTT, an older age and gamma-glutamyltransferase to all be independent risk factors related to hepatocarcinogenesis.

CONCLUSIONS

A DM pattern on the 75 g OGTT was thus found to be associated with hepatocarcinogenesis and the 75 g OGTT is considered to be useful for identifying this risk factor for HCC in patients with HCV.

Proteomic analysis of differentially expressed proteins in hepatitis B virus-related hepatocellular carcinoma tissues

BACKGROUND

Hepatocellular carcinoma (HCC), a major cause of cancer death in China, is preceded by chronic hepatitis and liver cirrhosis (LC). Although hepatitis B virus (HBV) has been regarded as a clear etiology of human hepatocarcinogenesis, the mechanism is still needs to be further clarified. In this study, we used a proteomic approach to identify the differential expression protein profiles between HCC and the adjacent non-tumorous liver tissues.

METHODS

Eighteen cases of HBV-related HCC including 12 cases of LC-developed HCC and 6 cases of chronic hepatitis B (CHB)-developed HCC were analyzed by two-dimensional electrophoresis (2-DE) combined with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), and the results were compared to those of paired adjacent non-tumorous liver tissues.

RESULTS

A total of 17 differentially expressed proteins with diverse biological functions were identified. Among these, 10 proteins were up-regulated, whereas the other 7 proteins were down-regulated in cancerous tissues. Two proteins, c-Jun N-terminal kinase 2 and ADP/ATP carrier protein were found to be up-regulated only in CHB-developed HCC tissues. Insulin-like growth factor binding protein 2 and Rho-GTPase-activating protein 4 were down-regulated in LC-developed and CHB-developed HCC tissues, respectively. Although 11 out of these 17 proteins have been already described by previous studies, or are already known to be involved in hepatocarcinogenesis, this study revealed 6 new proteins differentially expressed in HBV-related HCC.

CONCLUSION

These findings elucidate that there are common features between CHB-developed HCC and LC-developed HCC. The identified proteins are valuable for studying the hepatocarcinogenesis, and may be potential diagnostic markers or therapeutic targets for HBV-related HCC.

Elevated hepatic iron: a confounding factor in chronic hepatitis C

Historically, iron overload in the liver has been associated with the genetic disorders hereditary hemochromatosis and thalassemia and with unusual dietary habits. More recently, elevated hepatic iron levels also have been observed in chronic hepatitis C virus (HCV) infection. Iron overload in the liver causes many changes including induction of oxidative stress, damage to lysosomes and mitochondria, altered oxidant defense systems and stimulation of hepatocyte proliferation. Chronic HCV infection causes numerous pathogenic changes in the liver including induction of endoplasmic reticulum stress, the unfolded protein response, oxidative stress, mitochondrial dysfunction and altered growth control. Understanding the molecular and cellular changes that could occur in a liver which has elevated hepatic iron levels and in which HCV replication and gene expression are ongoing has clinical relevance and represents an area of research in need of further investigation.