title: A bifunctional platinum(II) complex capable of intercalation and hydrogen-bonding interactions with DNA: binding studies and cytotoxicity.
abstract: The interactions of [Pt(CNN)(4-dpt)]PF(6), (1; 4-dpt=2,4-diamino-6-(4-pyridyl)-1,3,5-triazine, HCNN=6-phenyl-2,2'-bipyridine) with double-stranded DNA, poly(dA-dT)(2), and poly(dG-dC)(2) were examined by spectroscopic, electrophoretic, and hydrodynamic methods. The spectroscopic data were analyzed with McGhee, van't Hoff, and Gibbs-Helmholtz equations. In a comparative study, [Pt(CNN)(py)]PF(6) (2; py=pyridine) was prepared and the nature of its binding towards DNA was investigated [preliminary results: ChemBioChem 2003, 4, 62-68]. For reactions with calf thymus DNA at 20 degrees C, the intrinsic binding constants for 1 and 2 are (4.6+/-0.2)x10(5) and (2.3+/-0.3)x10(4) mol(-1) dm(3), respectively. Results of DNA-binding reactions revealed that 1 and 2 preferentially bind to the AT sequence of duplex DNA. Intercalation is the preferred binding mode for 2, whereas both intercalation and minor-groove binding are observed for 1. Complex 1 is cytotoxic against a number of carcinoma cell lines, including KB-3-1, CNE-3, and HepG2, and remains potent against multidrug- or cisplatin-resistant KB-V-1 and CNE1 cell lines, for which the resistance ratios are 1.6 and 1.5, respectively. Importantly, 1 is almost an order of magnitude less toxic to the normal cell line CCD-19Lu (IC(50)=176+/-1.7 microM) and it selectively induced apoptosis leading to cancer cell death with less than 5 % detectable necrosis.
authors.affiliation: Department of Chemistry and Open Laboratory of Chemical Biology, of the Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
authors.forename: Dik-Lung
authors.initials: DL
authors.lastname: Ma
authors.forename: Chi-Ming
authors.initials: CM
authors.lastname: Che
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D004247:DNA / Q000737:chemistry / Q000187:drug effects*; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D006860:Hydrogen Bonding; D007364:Intercalating Agents / Q000737:chemistry / Q000494:pharmacology*; D009336:Necrosis; D009944:Organoplatinum Compounds / Q000737:chemistry / Q000494:pharmacology*; D011067:Poly dA-dT / Q000737:chemistry; D011089:Polydeoxyribonucleotides / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D014227:Triazines / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D007364:Intercalating Agents; D009944:Organoplatinum Compounds; D011089:Polydeoxyribonucleotides; D011725:Pyridines; D014227:Triazines; C478898:platinum(II) 6-phenyl-2,2'-bipyridine; D011067:Poly dA-dT; C019530:poly(dC-dG); D004247:DNA; D002945:Cisplatin