THE REDUCTIVE METABOLISM OF DIAZIQUONE (AZQ) IN THE S9 FRACTION OF MCF-7 CELLS - FREE-RADICAL FORMATION AND NAD(P)H - QUINONE-ACCEPTOR OXIDOREDUCTASE (DT-DIAPHORASE) ACTIVITY

被引：32

作者：

FISHER, GR ^{[1
]}

GUTIERREZ, PL ^{[1
]}

机构：

[1] UNIV MARYLAND,CTR CANC,DIV DEV THERAPEUT,655 W BALTIMORE ST,BALTIMORE,MD 21201

来源：

FREE RADICAL BIOLOGY AND MEDICINE | 1991年 / 10卷 / 06期

关键词：

DIAZIQUONE; FREE RADICALS; BIOREDUCTION; REDOX CYCLING; DT-DIAPHORASE; QUINONES; ANTICANCER AGENTS; BIOACTIVATION;

D O I：

10.1016/0891-5849(91)90044-4

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

The S9 fraction of MCF-7 human breast carcinoma cells has NAD(P)H (quinone-acceptor) oxidoreductase activity as measured by the reduction of dichlorophenol-indophenol (DCPIP). This reduction is dependent on the activators Tween-20 and bovine serum albumin and it is inhibitable by dicoumarol. The S9 fraction also has cytochrome c reductase activity which is approximately 29 times less than the two-electron reduction activity of NAD(P)H (quinone-acceptor) oxidoreductase. Diaziquone (AZQ) is a substrate for this NAD(P)H oxidoreductase active S9 fraction as judged by its enzymatic reduction detected spectrophotometrically and by electron spin resonance spectroscopy. Two-electron mediated enzymatic reduction of AZQ was evidenced by the formation of the colorless dihydroquinone (AZQH2) which could be followed at 340 nm. The production of the dihydroquinone was inhibitable by dicoumarol implicating NAD(P)H oxidoreductase in its formation. Under aerobic conditions, electron spin resonance spectroscopy showed evidence for the production of AZQ semiquinone (AZQH) and oxygen radicals. Under anaerobic conditions no oxygen radicals were observed, but the semiquinone was stable for hours. These results are also inhibitable by dicoumarol and suggest a two-step one-electron oxidation process of the dihydroquinone. The production of semiquinone and oxygen radicals as detected by electron spin resonance spectroscopy was more sensitive to dicoumarol when NADPH was used as cofactor (68% inhibition of OH and 65% inhibition of AZQH) than when NADH was used (28% inhibition of OH and 5% inhibition of AZQH). This suggests that NADH flavin reductases play a more important role in the one-electron reduction pathway of AZQ in MCF-7 S9 fraction than NADPH reductases. The reduction of AZQ by NAD(P)H (quinone-acceptor) oxidoreductase may play an important role in the bioreductive alkylating properties of AZQ.

引用

页码：359 / 370

页数：12

共 43 条

[1]

Schold, Friedman, Bjornsson, Falleta, Treatment of patients with recurrent primary brain tumors with AZQ, Neurology, 34, pp. 615-619, (1984)

[2]

Lee, Van Echo, Egorin, Nayar, Shulman, Schiffer, Diaziquone given as a continuous infusion is an active agent for relapsed adult acute nonlymphocyticleukemia, Blood, 67, pp. 182-187, (1986)

[3]

Schulman, Davis, Lee, Ellerton, Staszweski, Phase II study of continuous-infusion diaziquone in relapsed/refractory acute nonlymphocytic leukemia, Cancer Treat. Rep., 71, pp. 755-757, (1987)

[4]

Mossoba, Alizadeh, Gutierrez, mechanism for the reductive activation of diaziquone, J. Pharm. Sci., 74, pp. 1249-1254, (1985)

[5]

Szmigiero, Kohn, Mechanisms of DNA strand breakage and interstrand cross-linking by diaziridinylbenzoquinone (Diaziquone) in isolated nuclei from human cells, Cancer Res., 44, pp. 4453-4457, (1984)

[6]

Gutierrez, Mechanism(s) of bioreductive activation. The example of diaziquone (AZQ), Free Radic. Biol. Med., 6, pp. 405-445, (1989)

[7]

Sinha, Katki, Batist, Cowan, Myers, Differential formation of hydroxyl radicals by Adriamycin in sensitive and resistant MCF-7 human breast tumor cells: implications for the mechanism of action, Biochemistry, 26, pp. 3776-3781, (1987)

[8]

Ernster, DT diaphorase: a historical review, Chemica Scripta, 27 A, pp. 1-13, (1987)

[9]

Buffinton, Ollinger, Brunmark, Cadenas, DT-diaphorase-catalysed reduction of 1,4-naphthoquinone derivatives and glutathionyl-quinone conjugates, Biochem. J., 257, pp. 561-571, (1989)

[10]

Ernster, DT diaphorase, Methods in enzymology, pp. 309-317, (1967)

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