Mitomycin C is a clinically significant antineoplastic antibiotic used widely in combination chemotherapy for the treatment of patients with advanced breast cancer and cervical ovarian cancers. The mechanism of mitomycin C action in vivo remains an enigma. First, research has shown that mitomycin C acts principally as an electrophilic trapping agent that prevents efficient bonding to the target DNA. Second, recent studies have raised questions whether in vitro mitomycin C-DNA bonding investigations accurately reflect in vivo processes. We propose a multidisciplinary program to provide information concerning mitomycin C-DNA transformations. First, we will determine the key interactions that precede the initial bonding of the activated drug to DNA and examine if bonding is catalyzed by DNA. UV-visible, viscometric, and high-filed NMR studies will give information on the mechanism of drug-DNA binding and bonding and provide a solution structure of the precovalent complex. Information concerning the structural elements necessary for the drug-DNA recognition process will be obtained with specifically modified mitomycins and genomic DNAs, using the UVRABC assay. Second, we will determine if in vivo drug-DNA bonding is efficient and sequence selective, if these processes follow the same bonding rules found for in vitro transformation, and if chromatin structure and DNA-mediated processes affect mitomycin bonding. These fundamental questions are still unanswered because of the lack of suitable monitoring techniques. We advance the combined use of the UVRABC assay and the ligation-mediated polymerase chain reaction to follow mitomycin-DNA processes in cultured mammalian cells. Third, we will determine the activation and bonding pathways for two new classes of mitomycin agents to learn if novel routes exist for the efficient and selective bonding of mitomycins to DNA. Members of both classes of compounds are undergoing clinical trials. Knowledge from these studies will contribute to our understanding of the mitomycins and serve as the basis for the design of new DNA site-specific anticancer drugs.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Special Emphasis Panel (ZRG3-BNP (02))
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Beisler, John A
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University of Houston
Schools of Arts and Sciences
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Lee, Sang Hyup; Kohn, Harold (2009) Nucleophilic activation of a tetra-substituted mitomycin cyclic bis-disulfide. Chem Pharm Bull (Tokyo) 57:149-57
Lee, Sang Hyup; Kohn, Harold (2005) 7-N,7'-N'-(1"",2""-Dithianyl-3"",6""-dimethylenyl)bismitomycin C: synthesis and nucleophilic activation of a dimeric mitomycin. Org Biomol Chem 3:471-82
Lee, Sang Hyup; Kohn, Harold (2004) Cyclic disulfide C8 iminoporfiromycin: nucleophilic activation of a porfiromycin. J Am Chem Soc 126:4281-92
Na, Younghwa; Wang, Shuang; Kohn, Harold (2002) 7-N-(mercaptoalkyl)mitomycins: implications of cyclization for drug function. J Am Chem Soc 124:4666-77
Lee, Sang Hyup; Kohn, Harold (2002) Efficient synthesis of medium-sized cyclic ether diamines. J Org Chem 67:1692-5
Zewail-Foote, M; Li, V S; Kohn, H et al. (2001) The inefficiency of incisions of ecteinascidin 743-DNA adducts by the UvrABC nuclease and the unique structural feature of the DNA adducts can be used to explain the repair-dependent toxicities of this antitumor agent. Chem Biol 8:1033-49
Li, V S; Tang, M S; Kohn, H (2001) The effect of C(5) cytosine methylation at CpG sequences on mitomycin-DNA bonding profiles. Bioorg Med Chem 9:863-73
Na, Y; Li, V S; Nakanishi, Y et al. (2001) Synthesis, DNA cross-linking activity, and cytotoxicity of dimeric mitomycins. J Med Chem 44:3453-62
Li, V S; Reed, M; Zheng, Y et al. (2000) C5 cytosine methylation at CpG sites enhances sequence selectivity of mitomycin C-DNA bonding. Biochemistry 39:2612-8
Wang, S; Kohn, H (1999) Studies on the mode of action of mitomycin C(7) aminoethylene disulfides (BMS-181174 and KW-2149): reactivity of 7-N-(mercaptoethyl)mitomycin C. J Med Chem 42:788-90

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