Using electrophoresis and replication mapping, we show that the presence of DNA adducts of bifunctional antitumor cisplatin or monodentate [PtCl(dien)]Cl (dien = diethylenetriamine) in the substrate DNA inhibits eukaryotic topoisomerase 1 (top1) action, the adducts of cisplatin being more effective. The presence of camptothecin in the samples of platinated DNA markedly enhances effects of Pt-DNA adducts on top1 activity. Interestingly, the effects of Pt-DNA adducts on the catalytic activity of top1 in the presence of camptothecin differ depending on the sequence context. A multiple metallation of the short nucleotide sequences on the scissile strand, immediately downstream of the cleavage site impedes the cleavage by top1. On the other hand, DNA cleavage by top1 at some cleavage sites which were not platinated in their close proximity is notably enhanced as a consequence of global platination of DNA. We suggest that this enhancement of DNA cleavage by top1 may consist in its inability to bind to other cleavage sites platinated in their close neighborhood; thus, more molecules of top1 may become available for cleavage at the sites where top1 normally cleaves and where platination does not interfere.

• MeSH
• adukty DNA chemie   farmakologie   MeSH
• cisplatina analogy a deriváty   chemie   farmakologie   MeSH
• DNA-topoisomerasy I metabolismus   MeSH
• DNA chemie   metabolismus   MeSH
• inhibitory enzymů chemie   farmakologie   MeSH
• inhibitory topoisomerasy I * MeSH
• protinádorové látky chemie   farmakologie   MeSH
• štěpení DNA MeSH
• superhelikální DNA metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adukty DNA MeSH
• chlorodiethylenetriamine platinum MeSH Prohlížeč
• cisplatin-DNA adduct MeSH Prohlížeč
• cisplatina MeSH
• DNA-topoisomerasy I MeSH
• DNA MeSH
• inhibitory enzymů MeSH
• inhibitory topoisomerasy I * MeSH
• protinádorové látky MeSH
• superhelikální DNA MeSH

The global modification of mammalian and plasmid DNAs by the novel platinum compounds cis-[PtCl(2)(isopropylamine)(1-methylimidazole)] and trans-[PtCl(2)(isopropylamine)(1-methylimidazole)] and the reactivity of these compounds with reduced glutathione (GSH) were investigated in cell-free media using various biochemical and biophysical methods. Earlier cytotoxicity studies had revealed that the replacement of the NH(3) groups in cisplatin by the azole and isopropylamine ligands lowers the activity of cisplatin in both sensitive and resistant cell lines. The results of the present work show that this replacement does not considerably affect the DNA modifications by this drug, recognition of these modifications by HMGB1 protein, their repair, and reactivity of the platinum complex with GSH. These results were interpreted to mean that the reduced activity of this analog of cisplatin in tumor cell lines is due to factors that do not operate at the level of the target DNA. In contrast, earlier studies had shown that the replacement of the NH(3) groups in the clinically ineffective trans isomer (transplatin) by the azole and isopropylamine ligands results in a radical enhancement of its activity in tumor cell lines. Importantly, this replacement also markedly alters the DNA binding mode of transplatin, which is distinctly different from that of cisplatin, but does not affect reactivity with GSH. Hence, the results of the present work are consistent with the view and support the hypothesis systematically tested by us and others that platinum drugs that bind to DNA in a fundamentally different manner from that of conventional cisplatin may have altered pharmacological properties.

• MeSH
• bezbuněčný systém MeSH
• cirkulární dichroismus MeSH
• DNA chemie   účinky léků   MeSH
• glutathion chemie   účinky léků   MeSH
• kultivační média chemie   MeSH
• lidé MeSH
• organoplatinové sloučeniny chemie   farmakologie   MeSH
• protinádorové látky chemie   farmakologie   MeSH
• spektrofotometrie ultrafialová MeSH
• stereoizomerie MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dichloro(isopropylamine)(1-methylimidazole)diplatinum(II) MeSH Prohlížeč
• DNA MeSH
• glutathion MeSH
• kultivační média MeSH
• organoplatinové sloučeniny MeSH
• protinádorové látky MeSH