The levels of quinone reductases, superoxide dismutase and glutathione-related enzymatic activities in diethylstilbestrol-induced carcinogenesis in the kidney of male Syrian golden hamsters

Abstract

The level of quinone oxidoreductases (microsomal and cytosolic DT-diaphorase, NADPH-cytochrome P450 reductase and NADH-cytochrome b5 reductase), superoxide dismutase and glutathione-related enzymatic activities in diethylstilbestrol (DES)-induced carcinogenesis in kidney from Syrian golden hamsters are presented. Animals that exhibited two different stages of DES-induced carcinogenesis in kidney--pre- and neoplastic lesions and tumorous lesions (after 6 and 8 months of continuous exposure to DES respectively)--were studied in comparison to kidneys from control animals. A dramatic decrease in microsomal and cytosolic DT-diaphorase activities (13.6 and 37.8% of controls), as well as in glutathione disulphide reductase (39.5%), and less marked in superoxide dismutase (45.6%), NADH cytochrome b5 reductase (61.9%) glutathione transferase (GST) towards 1-chloro-2,4-dinitrobenzene (CDNB) (66.2%) and glutathione peroxidase (GSH-Px) (80%) activities, were observed in kidneys with pre- and neoplastic lesions. NADPH-cytochrome P450 reductase and GST activity towards 4-hydroxy-2,3-trans-nonenal (4-HNE) showed no statistically significant variation at this stage of carcinogenesis. In kidney from animals with tumorous lesions, all the enzymatic activities mentioned above decreased, except for superoxide dismutase, which was increased to 186% of the control activity. GST activity towards 4-HNE again showed no statistically significant variation. These results suggest that if one-electron reduction of diethylstilbestrol-4',4''-quinone (DESQ) occurs, it may play a very important role in the development of DES carcinogenesis (pre- and neoplastic lesions), since at this stage of carcinogenesis the primary defense mechanisms against the oxygen free radicals generated in this way, i.e. SOD activity, is reduced to less than a half of control values. Both cytosolic and microsomal DT-diaphorase activities are unable at this stage of carcinogenesis to promote effectively the two-electron reduction of DESQ, which would avoid the initial formation of superoxide anion. The consequences of these decreases may be an increased steady-state concentration of superoxide anion and hydrogen peroxide, which in the presence of iron might lead to lipid peroxidation. GST activity towards 4-HNE could be responsible for the possible higher steady-state concentration of this lipid peroxidation product during DES treatment. The induction of DT-diaphorase and its protective role in the prevention of the development of pre- and neoplastic lesions in kidney from Syrian golden hamster during DES treatment is also discussed.

Development and validation of a spectrophotometric assay for measuring the activity of NADH: cytochrome b5 reductase in human tumour cells

“…Methods reported in the literature do not appear to have been validated, i.e. the non-dicoumarol-inhibitable reduction of cytochrome c (Segura-Aguilar et al, 1990) or the NADHdependent reduction of cytochrome c (Plumb et al, 1994), and assume that cytochrome b5 reductase is the only enzyme responsible for the NADH-dependent reduction of cytochrome c. Our data indicate that this assumption is not valid. From Figure 4 it is evident that cytochrome b5 reductase activity does not account for all of the NADH-dependent reduction of cytochrome c in any cell line, as assessed using pHMB as a selective inhibitor.…”

“…The method of Segura-Aguilar et al (1990) also assumes that dicoumarol is a selective inhibitor of DT-diaphorase. We found that dicoumarol did not inhibit the NADH-dependent reduction of cytochrome c catalysed by mouse liver microsomes (data not shown).…”

“…To date, it has been assumed that either the non-dicoumarol-inhibitable reduction of cytochrome c (i.e. the residual activity observed in the presence of dicoumarol) (Segura-Aguilar et al, 1990) or the NADH-dependent reduction of cytochrome c (i.e. in the absence of menadione) (Plumb et al, 1994) are equivalent to cytochrome b5 reductase activity.…”

Antioxidant enzymes in liver of dab Limanda limanda from the North Sea

“…Whereas SOD, catalase and GPX respond to a number of pro-oxidant conditions, including changing oxygen tension, induction of DT-diaphorase is mainly related to exposure to xenobiotics. Increases in mRNA, protein and/or catalytic activity of the former enzymes have been demonstrated in bacteria following exposure to the redox cycling xenobiotics menadione and paraquat (SOD) and H202 (catalase) (Storz et al 1990 (SOD and catalase: Videla et al 1990), and carcinogenesis (variously, SOD, catalase and/or GPX: Vo et al 1988, Segura-Aguilar et al 1990, Reiners et al 1991. Mammalian DT-diaphorase is part of the gene battery that includes cytochrome P4501A1 and is induced both by xenobiotics that bind to the Ah receptor and certain pro-oxidant xenobiotics that affect gene regulation via other mechanisms (Nebert et al 1990).…”

Diet/toxin interactions

“…The hydroxy radicals thus formed modify the DNA bases into thymine glycol, 8-OH-dG and others. One example of oxygen radical mediated carcinogenesis is presented in figure 2 (Segura-Aguilar et al 1990). Diethylstilboestrol (DES), a renal carcinogen, is enzymically reduced by NADPH-cytochrome P-450 reductase , and an equilibrium between quinone and semiquinone gives rise to reactive oxygen radicals such as Superoxide anion and hydroxy radical.…”