Induction of CYP1A1 and CYP1B1 by benzo( k)fluoranthene and benzo( a)pyrene in T-47D human breast cancer cells: Roles of PAH interactions and PAH metabolites

• Published in: Toxicology and applied pharmacology Vol. 226; no. 3; pp. 213 - 224
• Main Authors: Spink, David C., Wu, Susan J., Spink, Barbara C., Hussain, Mirza M., Vakharia, Dilip D., Pentecost, Brian T., Kaminsky, Laurence S.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01-02-2008; Elsevier
• Subjects: 60 APPLIED LIFE SCIENCES; ANTHRACENE; Aryl Hydrocarbon Hydroxylases; Aryl hydrocarbon receptor; Benzo( a)pyrene; Benzo( k)fluoranthene; Benzo(a)pyrene - metabolism; Benzo(a)pyrene - toxicity; Biological and medical sciences; Biotransformation - drug effects; Breast Neoplasms - drug therapy; Breast Neoplasms - enzymology; Cell Line, Tumor; Chromatography, High Pressure Liquid; CYP1 induction; Cytochrome P-450 CYP1A1 - biosynthesis; Cytochrome P-450 CYP1B1; Cytochrome P-450 Enzyme System - biosynthesis; CYTOCHROMES; DIOXIN; DMSO; Dose-Response Relationship, Drug; Drug Combinations; Enzyme Induction - drug effects; ESTRADIOL; Female; Fluorenes - metabolism; Fluorenes - toxicity; GAS CHROMATOGRAPHY; Gas Chromatography-Mass Spectrometry; GLYCOLS; Gynecology. Andrology. Obstetrics; HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY; Humans; LUCIFERASE; Mammary gland diseases; MAMMARY GLANDS; MASS SPECTROSCOPY; Medical sciences; METABOLISM; METABOLITES; Microsomes, Liver - drug effects; Microsomes, Liver - enzymology; NEOPLASMS; PAH metabolism; POLYCYCLIC AROMATIC HYDROCARBONS; PYRENE; RECEPTORS; Toxicology; Tumors; BKF-2,3-diol; BAA-3,4-diol; 2- and 4-MeOE 2, 2- and 4-methoxyestradiol; Benzo( k)fluoranthene; BAA; EROD; DMSO; PAH metabolism; TCDD; AhR; DBAHA-5,6-diol; BKF-8,9-diol; BAP; Aryl hydrocarbon receptor; Benzo( a)pyrene; E 2; PAH; CYP or P450; TMS; CYP1 induction; BKF; 3-, 8-, and 9-OHBKF, 3-, 8; GC/MS; HPLC; Human; Enzyme; Induction; Metabolite; Cytochrome P450; Breast cancer; Benzo(a)pyrene; Malignant tumor; Polycyclic aromatic compound; Metabolism; Mammary gland diseases; Ah receptor; Cytochrome P450 1B1; Benzo(k)fluoranthene; Tumor cell; Cancer; Fluoranthene
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2007.08.024

The interactions of polycyclic aromatic hydrocarbons (PAH) and cytochromes P450 (CYP) are complex; PAHs are enzyme inducers, substrates, and inhibitors. In T-47D breast cancer cells, exposure to 0.1 to 1 μM benzo(
k)fluoranthene (BKF) induced CYP1A1/1B1-catalyzed 17β-estradiol (E
2) metabolism, whereas BKF levels greater than 1 μM inhibited E
2 metabolism. Time course studies showed that induction of CYP1-catalyzed E
2 metabolism persisted after the disappearance of BKF or co-exposed benzo(
a)pyrene, suggesting that BKF metabolites retaining Ah receptor agonist activity were responsible for prolonged CYP1 induction. BKF metabolites were shown, through the use of ethoxyresorufin
O-deethylase and CYP1A1-promoter-luciferase reporter assays to induce CYP1A1/1B1 in T-47D cells. Metabolites formed by oxidation at the C-2/C-3 region of BKF had potencies for CYP1 induction exceeding those of BKF, whereas C-8/C-9 oxidative metabolites were somewhat less potent than BKF. The activities of expressed human CYP1A1 and 1B1 with BKF as substrate were investigated by use of HPLC with fluorescence detection, and by GC/MS. The results showed that both enzymes efficiently catalyzed the formation of 3-, 8-, and 9-OHBKF from BKF. These studies indicate that the inductive effects of PAH metabolites as potent CYP1 inducers are likely to be additional important factors in PAH-CYP interactions that affect metabolism and bioactivation of other PAHs, ultimately modulating PAH toxicity and carcinogenicity.