title: Cellular resistance to the antitumor DNA topoisomerase II inhibitor S16020-2: importance of the N-[2(Dimethylamino)ethyl]carbamoyl side chain.
abstract: The new olivacine derivative S16020-2 (NSC-659687) is a DNA topoisomerase II inhibitor endowed with a remarkable antitumor activity against various experimental tumors. In vitro physicochemical properties of this compound, in particular its interaction with DNA and DNA topoisomerase II, were very similar to those of ellipticine derivatives, except for a strictly ATP-dependent mechanism of cleavable complex induction. From the Chinese hamster lung fibroblast cell line DC-3F, a subline resistant to S16020-2, named DC-3F/S16, was selected by adding stepwise increasing concentrations of the drug to the cell growth medium. Whereas DC-3F/9-OH-E cells, a DC-3F subline resistant to 9-hydroxy-ellipticine, are cross-resistant to S16020-2, DC-3F/S16 cells are only very weakly cross-resistant to ellipticine derivatives, indicating that, despite their structural similarity, these compounds may differ in their mechanisms of action. Uptake and efflux rates of S16020-2 were identical in the resistant and the sensitive cells. Topoisomerase IIalpha was expressed at the same level in both sensitive and resistant cells, whereas expression of the beta-enzyme was approximately 50% lower in the resistant cells. Sequencing of both alpha- and beta-isoform cDNAs revealed a point mutation that converts Arg(486) to a Gly in the alpha cDNA, whereas the beta cDNA was not modified. This amino acid substitution in a highly conserved sequence of the enzyme appears to be responsible for the resistance to S16020-2. Comparative analysis of the properties of the ellipticine and S16020-2-resistant cells suggests that S16020-2, which is a DNA intercalator, might also interact with this enzyme amino acid sequence through its side chain.
authors.affiliation: Centre National de la Recherche Scientifique UMR 8532, Physico-chimie et Pharmacologie des Macromolécules Biologiques, Institut Gustave Roussy, Villejuif, France.
authors.forename: S
authors.initials: S
authors.lastname: Le Mée
authors.forename: F
authors.initials: F
authors.lastname: Chaminade
authors.forename: C
authors.initials: C
authors.lastname: Delaporte
authors.forename: J
authors.initials: J
authors.lastname: Markovits
authors.forename: J M
authors.initials: JM
authors.lastname: Saucier
authors.forename: A
authors.initials: A
authors.lastname: Jacquemin-Sablon
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D015197:Carcinogenicity Tests; D003001:Cloning, Molecular; D006224:Cricetinae; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000032:analysis / Q000378:metabolism; D018432:Drug Resistance, Multiple / Q000502:physiology; D019008:Drug Resistance, Neoplasm; D004611:Ellipticines / Q000378:metabolism / Q000494:pharmacology*; D017422:Sequence Analysis, DNA; D059005:Topoisomerase II Inhibitors; D014407:Tumor Cells, Cultured
chemical_list: D000964:Antimetabolites, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D004611:Ellipticines; C101591:S 16020-2; D059005:Topoisomerase II Inhibitors; D004247:DNA; C008009:9-hydroxyellipticine; D004250:DNA Topoisomerases, Type II