title: Nonenzymatic reductive activation of 7-N-((2-([2-(gamma-L-glutamylamino)ethyl]dithio)ethyl))mitomycin C by thiol molecules: a novel mitomycin C derivative effective on mitomycin C-resistant tumor cells.
abstract: 7-N-((2-([2-(gamma-L-Glutamylamino)ethyl]dithio)ethyl))mitomycin C (KW-2149) is an analogue of mitomycin C (MMC) and has prominent activities against various tumors. We studied the antitumor effects of KW-2149 in MMC-resistant variants of human colon carcinoma HT-29 (HT-29/MMC) and mouse hepatoma Hepa-I (C4, B13NBii1) cells, which are deficient in DT-diaphorase and cytochrome P450 reductase, respectively. These enzymes mediate the reductive activation of MMC in the cells. Although HT-29/MMC and C4, B13NBii1 cells showed significant resistance to MMC, they showed sensitivity tl KW-2149 comparable to their parental tumors, indicating that DT-diaphorase and cytochrome P450 reductase could not be involved in the activation of KW-2149. In studying the activation mechanism of KW-2149, we found that glutathione (GSH) and cysteine significantly enhanced the cytotoxicity of KW-2149 in HT-29 cells. The DNA adduct of KW-2149 was increased when HT-29 cells or the isolated nuclei of the cells were incubated with KW-2149 in the presence of physiological concentrations of GSH and cysteine. KW-2149 alkylated calf thymus DNA in the presence of GSH and cysteine in vitro. These results indicate that activation of KW-2149 by thiol molecules, unlike MMC, could be an important activation mechanism of KW-2149 to form DNA adduct and to exert its cytotoxicity. This is the reason why KW-2149 is effective against MMC-resistant tumors with deficiencies in the MMC activation enzymes.
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: M
authors.initials: M
authors.lastname: Naito
authors.forename: T
authors.initials: T
authors.lastname: Tsuruo
mesh_terms: D019328:Buthionine Sulfoximine; D003110:Colonic Neoplasms / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004273:DNA, Neoplasm / Q000378:metabolism; D004347:Drug Interactions; D004351:Drug Resistance; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000378:metabolism; D016685:Mitomycin / Q000378:metabolism; D008937:Mitomycins; D010084:Oxidation-Reduction; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
chemical_list: D004273:DNA, Neoplasm; D008937:Mitomycins; D013438:Sulfhydryl Compounds; C057625:KW 2149; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D016685:Mitomycin; D003577:Cytochrome P-450 Enzyme System; D005978:Glutathione; D003545:Cysteine