title: Topoisomerase II-mediated DNA cleavage activity and irreversibility of cleavable complex formation induced by DNA intercalator with alkylating capability.
abstract: A group of chrysophanol and emodin derivatives with DNA-intercalating capability and with or without alkylating potential have been synthesized and shown to have antitumor activity in vitro. The topoisomerase II (Topo II)-mediated DNA cleavage activities induced by representative compounds 3-(2-chloroethylamino) methyl-1,8-dihydroxy-9,10-anthraquinone (SK-31690), 3-bis [(2-chloroethyl)amino]methyl-1,8-dihydroxy-9,10-anthraquinone (SK-31662), and 3-(2-hydroxyethylamino)methy-1,8-dihydroxy-9,10-anthraquinon e (SK-31694), and their cytotoxicities, have been investigated. All three compounds inhibited the kinetoplast DNA decatenation catalyzed by DNA Topo II. These compounds inhibited leukemia cell growth and stimulated, in a dose-dependent manner from 0.5 to 60 microM, the formation of Topo II-DNA cleavable complexes, when 3'-32P-labeled DNA was used. The mapping of Topo II-mediated DNA cleavage sites using HindIII-digested 3'-32P-labeled DNA showed that, at 10 microM, these compounds induced protein-linked DNA breaks that correlated with cytotoxicity, with respect to their maximal efficacy or the reciprocal concentration for the half-maximal effect. The reversibility study showed that the amounts of protein-linked DNA cleavage induced by 4'-(9-acridinylamino)methanesulfon-m-anisidide and VP-16 as well as SK-31694, which lacks alkylating potential, were markedly decreased during 30-sec exposure to 65 degrees or 0.5 M NaCl. In contrast, protein-linked DNA cleavages induced by SK-31662, which has two alkylating functionalities, and by SK-31690, which has one alkylating functionality in its structure, cannot be reversed during the 15-min exposure to 65 degrees or 0.5 M NaCl. These data suggest that Topo II is a major cellular target for cytotoxicity of these compounds. Furthermore, DNA intercalators with alkylating potential interact with Topo II-DNA cleavable complexes in an irreversible manner, with enhanced toxicity.
authors.affiliation: Laboratory of Biochemical Pharmacology, Memorial Sloan-Kettering Cancer Center, Cornell University Graduate School of Medical Sciences, New York, New York 10021.
authors.forename: X B
authors.initials: XB
authors.lastname: Kong
authors.forename: L
authors.initials: L
authors.lastname: Rubin
authors.forename: L I
authors.initials: LI
authors.lastname: Chen
authors.forename: G
authors.initials: G
authors.lastname: Ciszewska
authors.forename: K A
authors.initials: KA
authors.lastname: Watanabe
authors.forename: W P
authors.initials: WP
authors.lastname: Tong
authors.forename: F M
authors.initials: FM
authors.lastname: Sirotnak
authors.forename: T C
authors.initials: TC
authors.lastname: Chou
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology*; D000880:Anthraquinones / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D004264:DNA Topoisomerases, Type I / Q000187:drug effects; D004250:DNA Topoisomerases, Type II / Q000187:drug effects / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007364:Intercalating Agents / Q000494:pharmacology*; D007942:Leukemia, Experimental / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D007951:Leukemia, Myeloid / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D009690:Nucleic Acid Conformation / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D000477:Alkylating Agents; D000880:Anthraquinones; D004273:DNA, Neoplasm; D007364:Intercalating Agents; C073120:3-bis((2-chloroethyl)amino)methyl-1,8-dihydroxy-9,10-anthraquinone; C073121:3-(2-hydroxyethylamino)methyl-1,8-dihydroxy-9,10-anthraquinone; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II