title: Aryl hydrocarbon receptor mediates sensitivity of MCF-7 breast cancer cells to antitumor agent 2-(4-amino-3-methylphenyl) benzothiazole.
abstract: 2-(4-Amino-3-methylphenyl) benzothiazole (NSC 674495; DF 203) demonstrates drug uptake and metabolism by tumor cells sensitive to the antiproliferative activity of the drug [J Med Chem 1999;42:4172-4184]. In insensitive cells, little metabolism occurs. Because CYP1A1 can metabolize DF 203, the aryl hydrocarbon receptor (AhR) may mediate drug action. We demonstrate here that DF 203 increases CYP1A1 and CYP1B1 transcription in sensitive MCF-7 cells, accompanied by AhR translocation to the nucleus, increase in xenobiotic-responsive element (XRE)-driven luciferase activity, and induction of protein/DNA complexes on the XRE sequence of the CYP1A1 promoter. MDA-MB-435 and PC3 cells, resistant to DF 203, did not show drug-induced CYP1A1 and CYP1B1 gene expression. AhR was observed to be constitutively localized in the nucleus, with no induction of XRE-driven luciferase activity in transiently transfected cells and weak or no induction of protein/DNA complexes on the XRE sequence of CYP1A1. Taken together, these data elucidate a novel basis for antitumor drug action: induction in sensitive cells of a metabolizing system for the drug itself. These results suggest that clarification of the basis for differential engagement of AhR-related signaling in different tumor cell types may aid in further preclinical development and perhaps early clinical studies.
authors.affiliation: Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA. loaizaa@pop.nci.nih.gov
authors.forename: Andrea I
authors.initials: AI
authors.lastname: Loaiza-Pérez
authors.forename: Valentina
authors.initials: V
authors.lastname: Trapani
authors.forename: Curtis
authors.initials: C
authors.lastname: Hose
authors.forename: Sheo S
authors.initials: SS
authors.lastname: Singh
authors.forename: Jane B
authors.initials: JB
authors.lastname: Trepel
authors.forename: Malcolm F G
authors.initials: MF
authors.lastname: Stevens
authors.forename: Tracey D
authors.initials: TD
authors.lastname: Bradshaw
authors.forename: Edward A
authors.initials: EA
authors.lastname: Sausville
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000814:Aniline Compounds / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001189:Aryl Hydrocarbon Hydroxylases; D052160:Benzothiazoles; D001692:Biological Transport / Q000187:drug effects; D001943:Breast Neoplasms; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis / Q000235:genetics; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics; D004354:Drug Screening Assays, Antitumor; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D006801:Humans; D011401:Promoter Regions, Genetic / Q000187:drug effects; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*; D013844:Thiazoles / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D000814:Aniline Compounds; D000970:Antineoplastic Agents; D052160:Benzothiazoles; C122062:NSC 674495; D018336:Receptors, Aryl Hydrocarbon; D013844:Thiazoles; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1