title: Oxidative stress is insignificant in N1S1-transplanted hepatoma despite markedly declined activities of the antioxidant enzymes.
abstract: It has been proposed that persistent oxidative stress accounts for the increased levels of DNA damage in cancer tissues. We have examined the profile of anti-oxidant enzymes in a transplanted hepatic tumor model by injecting N1S1 rat hepatoma cells into the liver of Sprague-Dawley rats. The transplanted N1S1 tumors displayed characteristics resembling human hepatocellular carcinoma. The immunoreactivities of catalase (CAT), manganese-superoxide dismutase (Mn SOD), copper/zinc-SOD (Cu/Zn SOD), and glutathione peroxidase (GPx) were found to decrease significantly. The enzyme activity in tumors decreased 26.2-, 4.2-, 4.5-, and 5.4-fold for CAT, Mn SOD, Cu/Zn SOD, and GPx, respectively, relative to those in normal liver tissue from the same animals. In contrast, the mRNA levels of CAT and GPx in tumors decreased only 5- and 2-fold, respectively, and the mRNA levels of Cu/Zn SOD and Mn SOD showed either no change or an increase as compared to those of normal liver tissue. The contents of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) and thiobarbituric acid-reactive substances (TBARS) were comparable to those of normal controls. Furthermore, mitochondrial production of superoxide in tumors was 4 times lower than that in normal tissues. In conclusion, the data indicate that the reduced activities of anti-oxidant enzymes in the N1S1 tumor did not cause significant oxidative stress.
authors.affiliation: Institute of Anatomy and Cell Biology, National Yang-Ming University, Taipei 112, Taiwan, R.O.C.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Sung
authors.forename: C C
authors.initials: CC
authors.lastname: Juan
authors.forename: H C
authors.initials: HC
authors.lastname: Lee
authors.forename: P H
authors.initials: PH
authors.lastname: Yin
authors.forename: C W
authors.initials: CW
authors.lastname: Chi
authors.forename: H H
authors.initials: HH
authors.lastname: Ku
authors.forename: A F
authors.initials: AF
authors.lastname: Li
authors.forename: Y H
authors.initials: YH
authors.lastname: Wei
authors.forename: H J
authors.initials: HJ
authors.lastname: Tsay
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D002374:Catalase / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D008114:Liver Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology; D016031:Liver Transplantation; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase