title: Fluorinated 2-(4-amino-3-methylphenyl)benzothiazoles induce CYP1A1 expression, become metabolized, and bind to macromolecules in sensitive human cancer cells.
abstract: Fluorinated 2-(4-amino-3-methylphenyl)benzothiazoles possess potent antiproliferative activity against certain cancer cells, similar to the unfluorinated 2-(4-amino-3-methylphenyl)benzothiazole (DF 203, NSC 674495). In "sensitive" cancer cells, DF 203 is metabolized by, can induce expression of, and binds covalently to CYP1A1. Metabolism appears to be essential for its antiproliferative activity through DNA adduct formation. However, a biphasic dose-response relationship compromises its straightforward development as a chemotherapeutic agent. We investigated whether fluorinated benzothiazoles inhibit cancer cell growth without the biphasic dose-response, and whether the fluorinated benzothiazoles are also metabolized into reactive species, with binding to macromolecules in sensitive cancer cells. One fluorinated benzothiazole, 2-(4-amino-methylphenyl)-5-fluorobenzothiazole (5F 203, NSC 703786) did exhibit potent, antiproliferative activity without a biphasic dose-response. The fluorinated benzothiazoles were also metabolized only in cells, which subsequently showed evidence of cell death. We used microsomes from genetically engineered human B-lymphoblastoid cells expressing cytochromes P450 (CYP1A1, CYP1A2, or CYP1B1) to clarify the basis for fluorinated benzothiazole metabolism. 5F 203 induced CYP1A1 and CYP1B1 mRNA expression in sensitive breast and renal cancer cells, whereas 5F 203 induced CYP1A1 mRNA but not CYP1B1 mRNA expression in sensitive ovarian cancer cells. 5F 203 did not induce CYP1A1 or CYP1B1 mRNA expression in any "resistant" cancer cells. The fluorinated benzothiazoles induced CYP1A1 protein expression exclusively in sensitive cells. [14C]5F 203 bound substantially to subcellular fractions in sensitive cells but only minimally in resistant cells. These data are concordant with the antiproliferative activity of fluorinated benzothiazoles deriving from their ability to become metabolized and bind to macromolecules within sensitive cells.
authors.affiliation: Biological Testing Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD 21701, USA.
authors.forename: Eileen
authors.initials: E
authors.lastname: Brantley
authors.forename: Valentina
authors.initials: V
authors.lastname: Trapani
authors.forename: Michael C
authors.initials: MC
authors.lastname: Alley
authors.forename: Curtis D
authors.initials: CD
authors.lastname: Hose
authors.forename: Tracey D
authors.initials: TD
authors.lastname: Bradshaw
authors.forename: Malcolm F G
authors.initials: MF
authors.lastname: Stevens
authors.forename: Edward A
authors.initials: EA
authors.lastname: Sausville
authors.forename: Sherman F
authors.initials: SF
authors.lastname: Stinson
mesh_terms: D000970:Antineoplastic Agents / Q000493:pharmacokinetics* / Q000494:pharmacology*; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D015153:Blotting, Western; D045744:Cell Line, Tumor; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis* / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism; D065633:Cytochrome P-450 CYP1B1; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D006801:Humans; D007202:Indicators and Reagents; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D009369:Neoplasms / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012235:Rhodamines; D013778:Tetrazolium Salts; D013844:Thiazoles / Q000493:pharmacokinetics* / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D007202:Indicators and Reagents; D012333:RNA, Messenger; D012235:Rhodamines; D013778:Tetrazolium Salts; D013844:Thiazoles; C022027:lissamine rhodamine B; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2; D065633:Cytochrome P-450 CYP1B1; C022616:thiazolyl blue