title: Aryl hydrocarbon hydroxylase activity in chemically induced and toremifene-treated mammary tumors in rats.
abstract: Aryl hydrocarbon hydroxylase (AHH) and NADPH-cytochrome P450 reductase (NCR) activity of microsomes from liver, lungs, uterus and mammary tumors in dimethylbenzanthracene-induced and toremifene-treated female Sprague-Dawley rats were studied. AHH and NCR activity in tumors and uteri was low compared with that in livers and lungs. The distribution of AHH in tumors was wide and skewed. It varied in different tumors of the same animal as widely as between different animals. The enzyme activity in tumors did not correlate with that in the liver, lungs or uterus of the same animal. Toremifene had no effect on AHH or NCR in tumor or liver, but it decreased them in lungs. Tumor AHH activity correlated with its overall growth rate and development stage. The results suggest that malignant transformation leading to the defect in growth regulation also confuses the complex regulatory system of AHH activity.
authors.affiliation: Department of Pharmacology, University of Turku, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Pyykkö
authors.forename: S
authors.initials: S
authors.lastname: Ala-Uotila
authors.forename: U M
authors.initials: UM
authors.lastname: Jaakkola
authors.forename: M
authors.initials: M
authors.lastname: Lähde
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000187:drug effects / Q000378:metabolism*; D004354:Drug Screening Assays, Antitumor; D005260:Female; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008168:Lung / Q000187:drug effects / Q000201:enzymology; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000201:enzymology; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000188:drug therapy / Q000201:enzymology*; D009251:NADPH-Ferrihemoprotein Reductase / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017312:Toremifene / Q000627:therapeutic use*; D014599:Uterus / Q000187:drug effects / Q000201:enzymology
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene; D017312:Toremifene; D001189:Aryl Hydrocarbon Hydroxylases; D009251:NADPH-Ferrihemoprotein Reductase