title: DNA damage and cell cycle arrest induced by 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203, NSC 703786) is attenuated in aryl hydrocarbon receptor deficient MCF-7 cells.
abstract: The fluorinated benzothiazole analogue 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203, NSC 703786) is a novel agent with potent and selective antitumour properties and, in the form of its L-lysylamide prodrug Phortress (NSC 710305), is a current candidate for early phase clinical studies. Previous findings have indicated that cytochrome P450 1A1 (CYP1A1) may play a role in the antitumour activity of molecules in the benzothiazole series including the nonfluorinated parent compound 2-(4-amino-3-methylphenyl)benzothiazole (DF 203, NSC 674495) (Kashiyama et al, 1999; Chua et al, 2000; Loaiza-Pérez et al, 2002). In this study, we assessed and verified that a fully functional aryl hydrocarbon receptor (AhR) signalling pathway is a necessary requisite for the induction of efficient cytotoxicity by 5F 203 in MCF-7 wild-type sensitive cells. Drug exposure caused MCF-7 sensitive cells to arrest in G(1) and S phase, and induced DNA adduct formation, in contrast to AhR-deficient AH(R100) variant MCF-7 cells. In sensitive MCF-7 cells, induction of CYP1A1 and CYP1B1 transcription (measured by luciferase reporter assay and real-time reverse transcriptase-polymerase chain reaction (RT-PCR)), and 7-ethoxyresorufin-O-deethylase (EROD) activity was demonstrated, following treatment with 5F 203. In contrast, in resistant AH(R100) cells, drug treatment did not affect CYP1A1 and CYP1B1 transcription and EROD activity. Furthermore, AH(R100) cells failed to produce either protein/DNA complexes on the xenobiotic responsive element (XRE) sequence of CYP1A1 promoter (measured by electrophoretic mobility shift assay) or DNA adducts. The data confirm that activation of the AhR signalling pathway is an important feature of the antitumour activity of 5F 203.
authors.affiliation: School of Pharmaceutical Sciences, University of Nottingham, UK.
authors.forename: V
authors.initials: V
authors.lastname: Trapani
authors.forename: V
authors.initials: V
authors.lastname: Patel
authors.forename: C-O
authors.initials: CO
authors.lastname: Leong
authors.forename: H P
authors.initials: HP
authors.lastname: Ciolino
authors.forename: G C
authors.initials: GC
authors.lastname: Yeh
authors.forename: C
authors.initials: C
authors.lastname: Hose
authors.forename: J B
authors.initials: JB
authors.lastname: Trepel
authors.forename: M F G
authors.initials: MF
authors.lastname: Stevens
authors.forename: E A
authors.initials: EA
authors.lastname: Sausville
authors.forename: A I
authors.initials: AI
authors.lastname: Loaiza-Pérez
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D002851:Chromatography, High Pressure Liquid; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics / Q000378:metabolism; D065633:Cytochrome P-450 CYP1B1; D018736:DNA Adducts / Q000032:analysis / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects*; D004790:Enzyme Induction / Q000187:drug effects; D006801:Humans; D018336:Receptors, Aryl Hydrocarbon / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013844:Thiazoles / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: C425784:2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole; D018736:DNA Adducts; D018336:Receptors, Aryl Hydrocarbon; D013844:Thiazoles; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1