8-hydroxy-2--deoxyguanosine and Hepatitis

Hepatocyte apoptosis is a key feature of chronic liver disease including viral hepatitis and steatohepatitis. A previous study demonstrated that absence of the Bcl-2 family protein Mcl-1 led to increased hepatocyte apoptosis and development of liver tumors in mice. Since Mcl-1 not only inhibits the mitochondrial pathway of apoptosis but can also inhibit cell cycle progression and promote DNA repair, it remains to be proven whether the tumor suppressive effects of Mcl-1 are mediated by prevention of apoptosis.. We examined liver tumor development, fibrogenesis, and oxidative stress in livers of hepatocyte-specific knockout (KO) of Mcl-1 or Bcl-xL, another key antagonist of apoptosis in hepatocytes. We also examined the impact of additional KO of Bak, a downstream molecule of Mcl-1 towards apoptosis but not the cell cycle or DNA damage pathway, on tumor development, hepatocyte apoptosis, and inflammation.. Bcl-xL KO led to a high incidence of liver tumors in 1.5-year-old mice, similar to Mcl-1 KO. Bcl-xL- or Mcl-1-deficient livers showed higher levels of TNF-α production and oxidative stress than wild-type livers at as early as 6 weeks of age and oxidative DNA damage at 1.5 years. Deletion of Bak significantly inhibited hepatocyte apoptosis in Mcl-1 KO mice and reduced the incidence of liver cancer, coinciding with reduction of TNF-α production, oxidative stress, and oxidative DNA damage in non-cancerous livers.. Our findings strongly suggest that chronically increased apoptosis in hepatocytes is carcinogenic and offer genetic evidence that inhibition of apoptosis may suppress liver carcinogenesis in chronic liver disease.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aging; Animals; Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; bcl-X Protein; Carcinoma, Hepatocellular; Deoxyguanosine; Gene Expression Regulation, Neoplastic; Genotype; Hepatitis; Hepatocytes; Humans; Liver Neoplasms; Mice; Mice, Knockout; Myeloid Cell Leukemia Sequence 1 Protein; Oxidative Stress; Proto-Oncogene Proteins c-bcl-2; Tumor Necrosis Factor-alpha

Topical application of lipopolysaccharide and proteases to the gingival sulcus induced not only periodontal inflammation but also detectable liver changes in rats fed a normal diet. However, these changes in the liver were not sufficient to induce pathological consequences. The purpose of the present study was to investigate whether gingival inflammation-induced liver change would have more dramatic pathological consequences in rats fed a high-cholesterol diet compared with the effect of the high-cholesterol diet alone.. Twenty-four male Wistar rats were divided into four groups. During an 8 week experimental period, two groups were fed a normal diet and the other two were fed a high-cholesterol diet containing 1% cholesterol (w/w) and 0.5% cholic acid (w/w). Four weeks prior to the end of the experimental period, one of each of the dietary groups received daily topical application of lipopolysaccharide and proteases to the gingival sulcus, while the other was treated with pyrogen-free water.. In the rats without application of lipopolysaccharide and proteases, the serum level of hexanoyl-lysine, scores of steatosis and inflammation, and concentration of 8-hydroxydeoxyguanosine in liver of rats fed a high-cholesterol diet were higher than in those fed a normal diet. In rats fed a high-cholesterol diet, the scores of steatosis and inflammation and the concentration of 8-hydroxydeoxyguanosine in the liver of rats with application of lipopolysaccharide and proteases were higher than in those without.. In a rat model, application of lipopolysaccharide and proteases to the gingival sulcus augmented the effect of a high-cholesterol diet on steatosis, inflammation and oxidative damage in the liver.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Administration, Topical; Alanine Transaminase; Animals; Aspartate Aminotransferases; Bacterial Proteins; C-Reactive Protein; Cholesterol, Dietary; Cholic Acid; Deoxyguanosine; Escherichia coli; Fatty Liver; Gingiva; Hepatitis; Lipid Peroxides; Lipopolysaccharides; Liver; Liver Diseases; Lysine; Male; Mitochondria, Liver; Peptide Hydrolases; Periodontitis; Random Allocation; Rats; Rats, Wistar; Reactive Oxygen Species; Streptomyces griseus

To assess the effect of lactoferrin on oxidative liver damage and its mechanism, we used Long-Evans Cinnamon (LEC) rats that spontaneously develop fulminant-like hepatitis and lethal hepatic failure.. Four-week-old female LEC rats were divided into the untreated and treated groups. The latter was fed bovine lactoferrin at 2% mixed with conventional diet.. The cumulative survival rates were 75.0% vs. 100% at 14 weeks, 37.5% vs. 91.7% at 15 weeks, and 12.5% vs. 91.7% at 16 weeks, respectively, for untreated and treated rats (P=0.0008). The 8-OHdG levels in liver mitochondrial DNA and malondialdehyde in plasma and liver tissues were significantly lower in treated than untreated rats (P<0.001, =0.017 and 0.034, respectively). Mitochondrial DNA mutations were more common in untreated rats. OGG1 mRNA and protein expression levels were significantly lower in untreated than treated rats (P=0.003 and 0.007, respectively). Hypermethylation of the second CpG island located upstream of OGG1 gene was observed in untreated rats.. Our findings indicated that lactoferrin inhibits oxidative liver damage in LEC rats. Lactoferrin could be potentially useful for the treatment of oxidative stress-induced liver diseases.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Caspase 3; Cattle; CpG Islands; Deoxyguanosine; Disease Models, Animal; DNA Damage; DNA Glycosylases; DNA Methylation; DNA Repair; DNA, Mitochondrial; Down-Regulation; Female; Hepatitis; Lactoferrin; Liver; Liver Failure, Acute; Malondialdehyde; Mitochondria, Liver; Rats; Rats, Inbred LEC

8-Hydroxydeoxyguanosine (8-OHdG) is a promutagenic DNA lesion produced by oxygen radicals and is recognized as a useful marker in estimating DNA damage induced by oxidative stress.. Hepatic expression of 8-OHdG was immunohistochemically investigated in control and diseased human livers.. While no positive immunolabeling for 8-OHdG was observed in control livers, 8-OHdG was widely evident in diseased livers. Nuclear expression of 8-OHdG in the hepatocytes and bile duct cells were found in various forms of chronic hepatitis. 8-OHdG-positive hepatocytes were especially abundant in the periportal area with piecemeal necrosis and prominent cell infiltration. The number of positive hepatocytes significantly increased with the progression of severity of chronic hepatitis activity (r(s)=0.68, P<0.05). In alcoholic liver disease, nuclear expression of 8-OHdG was detected in the hepatocytes in the area of alcoholic hepatitis. Regarding primary biliary cirrhosis, 8-OHdG was preferentially detected in the nuclei of injured bile ducts (11 of 12 cases, 91.7%) and occasionally (2 of 12 cases, 16.7%) in the nuclei of hepatocytes around the bile duct lesions.. These results indicate that oxidative DNA damage is common in various forms of chronic liver disease suggesting a possible link between chronic inflammation and hepatocarcinogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Bile Duct Diseases; Biomarkers; Deoxyguanosine; DNA Damage; Hepatitis; Hepatitis B, Chronic; Hepatitis C, Chronic; Humans; Immunohistochemistry; Liver; Liver Cirrhosis, Biliary; Liver Diseases; Liver Diseases, Alcoholic; Middle Aged; Mitotic Index; Necrosis; Oxidation-Reduction

The Long-Evans Cinnamon (LEC) rat is a mutant strain characterized by abnormal copper metabolism and a high incidence of hepatitis and hepatoma. Using a yeast-based assay which scores mutants in p53 gene transcripts as red colonies, we detected frequent mutations in the liver of LEC rats. The majority (50-60%) of these were frameshift mutations caused by the insertion of an extra adenine (A) in the regions containing six consecutive adenines. The rate of A insertion was calculated to be 6.9-9.0% of the total p53 cDNA. Insertions of an extra adenine were found almost exclusively in the mRNA (cDNA), especially in the (A)(6) tract located at the most 5'-side (exon 4) among the three (A)(6) tracts (exons 4, 7, and 8), but rarely in the corresponding sites of genomic DNA. Wild-type p53 cDNA was transcribed in vitro into mRNA with the use of SP6 RNA polymerase and tested by the yeast functional assay. Subsequent sequencing detected A insertions at an overall rate of 1.6% in exons 7 and 8 but none in exon 4. This indicates that the A insertion in the exon 4 (A)(6) tract was an in vivo phenomenon rather than an artifact in reverse transcription or polymerase chain reaction. The percentage of red colonies increased sharply to about 20% of the liver samples in the acute hepatitis stage, and returned to control level of those in the chronic hepatitis stage, and increased again slightly to those in the neoplastic stage. The percentage of red colonies correlated with the serum GOT level (r=0.96, p<0.001) but not with the contents of copper and 8-hydroxydeoxyguanosine in the liver of LEC rats. Ethanol treatment of hepatic cell lines also increased the rate of transcriptional slippage at the (A)(6) tract. These findings indicate that cellular damage is responsible for the increase in the rate of mutation at the transcriptional level, and suggest that cellular damage degrades transcriptional fidelity, thereby further impairing cellular functions.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenine; Aging; Animals; Aspartate Aminotransferases; Copper; Deoxyguanosine; DNA, Complementary; Ethanol; Genes, p53; Hepatitis; Liver; Mutagenesis, Insertional; Mutation; Rats; Rats, Inbred LEC; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Saccharomyces cerevisiae; Transcription, Genetic; Transfection

Acute hepatitis spontaneously develops in the Long-Evans Cinnamon rat at the age of 4 mo, and eventually hepatocellular carcinoma develops after the chronic hepatitis that persists for over a year. Previously, abnormal copper accumulation was found in the livers of Long-Evans Cinnamon rats from birth, and it was reported that short-term administration of D-penicillamine, a copper-chelating agent, prevented acute hepatitis in Long-Evans Cinnamon rats. In this study we investigated whether long-term administration of D-penicillamine could also prevent chronic hepatitis and subsequent hepatocellular carcinoma in Long-Evans Cinnamon rats. During long-term observation, which was continued from 11 to 70 wk after birth, no elevation of serum transaminase levels was observed in the Long-Evans Cinnamon rats treated with D-penicillamine. Moreover, no histological changes characteristic of the chronic hepatitis were observed in D-penicillamine-treated Long-Evans Cinnamon rats, which were killed at 70 wk of age. Furthermore, placental glutathione S-transferase-positive foci, described as a marker for preneoplastic lesions in the liver, were not detected, and thus hepatocarcinogenesis was completely prevented in D-penicillamine-treated Long-Evans Cinnamon rats. We also found that the amount of 8-hydroxy-deoxyguanosine, one of oxidative DNA damage products in the liver, was decreased in the Long-Evans Cinnamon rats treated with D-penicillamine. These findings suggest that a process of the prolonged liver-cell injury and regeneration was essential for spontaneous development of hepatocellular carcinoma in Long-Evans Cinnamon rats with abnormal copper metabolism.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Alanine Transaminase; Animals; Anticarcinogenic Agents; Aspartate Aminotransferases; Carcinoma, Hepatocellular; Copper; Deoxyguanosine; DNA; Female; Hepatitis; Liver; Liver Neoplasms; Male; Penicillamine; Rats; Rats, Inbred Strains; Time Factors