title: Effects of quinolone derivatives on eukaryotic topoisomerase II. A novel mechanism for enhancement of enzyme-mediated DNA cleavage.
abstract: The effects of two novel quinolone derivatives, CP-67,804 and CP-115,953 (the 1-ethyl and 1-cyclopropyl derivatives of 6,8-difluoro-7-(4-hydroxyphenyl)-4-quinolone-3-carboxylic acid, respectively), on the enzymatic activities of Drosophila melanogaster topoisomerase II were examined. Both drugs enhanced the enzyme's pre- and post-strand passage DNA cleavage activities. CP-67,804 was nearly as potent an enhancer as etoposide, while CP-115,953 was approximately 2 times more potent than this topoisomerase II-targeted antineoplastic drug. In contrast to etoposide, which stabilizes enzyme-DNA cleavage complexes primarily by inhibiting topoisomerase II-mediated DNA religation, neither quinolone impaired the enzyme's ability to religate cleaved DNA. To further assess the characteristics of these unusual quinolone derivatives, the cytotoxic effects of CP-67,804 and CP-115,953 toward wild-type Chinese hamster ovary cells and VpmR-5 cells (an epipodophyllotoxin-resistant Chinese hamster ovary line) were examined. Both quinolones were cytotoxic to the wild-type cells. CP-115,953 was the more potent agent and displayed a level of cytotoxicity similar to that of etoposide. Finally, the VpmR-5 line showed cross-resistance to CP-67,804 (approximately 3.7-fold) and CP-115,953 (approximately 1.3-fold). Although quinolone cross-resistance was less pronounced than observed for etoposide (approximately 12-fold), it indicates that topoisomerase II is a physiological target for CP-67,804 and CP-115,953 in mammalian cells. These findings strongly suggest that these quinolone derivatives represent a novel class of topoisomerase II-targeted drugs which have potential as antineoplastic agents.
authors.affiliation: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146.
authors.forename: M J
authors.initials: MJ
authors.lastname: Robinson
authors.forename: B A
authors.initials: BA
authors.lastname: Martin
authors.forename: T D
authors.initials: TD
authors.lastname: Gootz
authors.forename: P R
authors.initials: PR
authors.lastname: McGuirk
authors.forename: M
authors.initials: M
authors.lastname: Moynihan
authors.forename: J A
authors.initials: JA
authors.lastname: Sutcliffe
authors.forename: N
authors.initials: N
authors.lastname: Osheroff
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology* / Q000633:toxicity; D002384:Catalysis; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000187:drug effects / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000187:drug effects / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000201:enzymology; D004587:Electrophoresis, Agar Gel; D005047:Etoposide / Q000494:pharmacology; D024841:Fluoroquinolones; D006868:Hydrolysis; D015394:Molecular Structure; D015363:Quinolones / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D015363:Quinolones; C070115:CP 67804; C070116:CP 115953; D005047:Etoposide; D004247:DNA; D004250:DNA Topoisomerases, Type II