Human DNA‐topoisomerase I activity is affected by bis‐netropsin's binding to DNA minor groove

Abstract

SUMMARYBis-netropsins (bis-Nts) are known to be efficient inhibitors of human DNA topoisomerase (topo) I with a higher antitumor activity than netropsin. New sequence-specific derivatives of bis-Nts were used for modulation of topo I-mediated DNA cleavage with and without camptothecin (CPT). Relation between the bis-Nts binding sites and topo I cleavage sites has been analyzed with the plasmid DNA constructs generated by insertion of synthetic oligonucleotides containing various topo I-cleavage and bis-Nt-binding sites. These constructs offer an opportunity to study minor groove binders effects on the topo I reaction on DNA. Three major effects: (i) bis-Nt -mediated disappearance of some of the topo I cleavage sites; (ii) enhancement of some other sites, and, (iii) generation of new cleavage sites, have been found and analyzed. These effects demonstrate that bis-Nts drastically change the topo Imediated DNA cleavage.

Raman and surface-enhanced Raman scattering spectroscopy of bis-netropsins and their DNA complexes

“…The differences in the molecular mechanism of DNA binding by bis‐Nts may account for their capacity to inhibit the catalytic activities of different DNA‐binding enzymes. Indeed, our experiments on the influence of these bis‐Nts on the activity of human DNA topoisomerase I showed that ligands with different orientations of Nt fragments modulate the enzyme activity in different ways 14…”

“…Recent studies demonstrated that certain bis‐Nts possess a several‐fold higher antitumor and antiviral activity than Nt that is due to modulation or inhibition of the different DNA‐binding enzymes 13–15. We previously synthesized a series of high sequence‐specific bis‐Nts16 and analyzed their ability to bind DNA and inhibit a number of DNA‐directed enzymes 9, 11.…”

“…We previously synthesized a series of high sequence‐specific bis‐Nts16 and analyzed their ability to bind DNA and inhibit a number of DNA‐directed enzymes 9, 11. Very recently we described a few effects of several new bis‐Nts on the human DNA topoisomerase I, an important clinical target of antitumor drugs: the disappearance of some of the topoisomerase I specific DNA cleavage sites; enhancement of some other sites; and, moreover, induction of the new DNA cleavage sites by the bis‐Nts 14. All these effects that determine the potential of bis‐Nts for inhibition of human topoisomerase I and, consequently, their antitumor activity, require detailed analysis of the structural features induced by these ligands on the DNA level.…”

DNA Sequence-Specific Ligands: XII. Synthesis and Cytological Studies of Dimeric Hoechst 33258 Molecules

“…This structure enables the orientation and fixing these Ä · í -recognizing pyrrolecarboxamide blocks in the complex with DNA [5,6]. The study of physicochemical [4,6] and biochemical [1,[6][7][8][9][10] properties of these DNA complexes with dimeric ligands showed that the netropsine fragments are specifically bound by two Ä · í base pair clusters. Later, this approach was DNA Sequence-Specific Ligands: XII.…”

Molecular Determinants of Site-specific Inhibition of Human DNA Topoisomerase I by Fagaronine and Ethoxidine

“…DNA Plasmid Constructs-Preparation of the top I DNA substrates in the form of plasmid constructs containing top I-specific and CPT-dependent cleavage sites was described (23). The constructs were purified from the cells and analyzed by DNA sequencing method of Sanger (24).…”