When antitumor platinum drugs react with DNA they form various types of intrastrand and interstrand cross-links (CLs). One class of new antitumor platinum compounds comprises bifunctional Pt(II) compounds based on the dinuclear or trinuclear geometry of leaving ligands. It has been shown that the DNA-binding modes of dinuclear or trinuclear bifunctional Pt(II) agents are distinct from those of mononuclear cisplatin, forming markedly more intramolecular interstrand CLs. However, at least two types of DNA interstrand cross-linking by bifunctional Pt(II) complexes can be envisaged, depending on whether the platinum complex coordinates to the bases in one DNA molecule (intramolecular interstrand CLs) or in two different DNA duplexes (interduplex CLs). We hypothesized that at least some antitumor bifunctional poly(di/tri)nuclear complexes could fulfill the requirements placed on interduplex DNA cross-linkers. To test this hypothesis we studied the interduplex cross-linking capability of a representative of antitumor polynuclear agents, namely, dinuclear Pt(II) complex [{trans-PtCl(NH(3))(2)}(2)-μ-{trans-(H(2)N(CH(2))(6)NH(2)(CH(2))(2)NH(2)(CH(2))(6)NH(2))}](4+) (BBR3535). The investigations were conducted under molecular crowding conditions mimicking environmental conditions in the cellular nucleus, namely, in medium containing ethanol, which is a commonly used crowding agent. We found with the aid of native agarose gel electrophoresis that the DNA interduplex cross-linking efficiency of BBR3535 under molecular crowding conditions was remarkable: the frequency of these CLs was 54%. In contrast, the interduplex cross-linking efficiency of mononuclear cisplatin or transplatin was markedly lower (approximately 40-fold or 18-fold, respectively). We suggest that the production of interduplex CLs in addition to other DNA intramolecular adducts may provide polynuclear Pt(II) compounds with a wider spectrum of cytotoxicity.

• MeSH
• adukty DNA chemie   metabolismus   MeSH
• DNA chemie   metabolismus   MeSH
• interkalátory chemie   farmakologie   MeSH
• lidé MeSH
• nádory farmakoterapie   MeSH
• organoplatinové sloučeniny chemie   farmakologie   MeSH
• protinádorové látky chemie   farmakologie   MeSH
• reagencia zkříženě vázaná chemie   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adukty DNA MeSH
• DNA MeSH
• interkalátory MeSH
• organoplatinové sloučeniny MeSH
• protinádorové látky MeSH
• reagencia zkříženě vázaná MeSH

A combination of biophysical, biochemical, and computational techniques was used to delineate mechanistic differences between the platinum-acridine hybrid agent [PtCl(en)(L)](NO(3))(2) (complex 1, en = ethane-1,2-diamine, L = 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea) and a considerably more potent second-generation analogue containing L' = N-[2-(acridin-9-ylamino)ethyl]-N-methylpropionamidine (complex 2). Calculations at the density functional theory level provide a rationale for the binding preference of both complexes for guanine-N7 and the relatively high level of adenine adducts observed for compound 1. A significant rate enhancement is observed for binding of the amidine-based complex 2 with DNA compared with the thiourea-based prototype 1. Studies conducted with chemical probes and on the bending and unwinding of model duplex DNA suggest that adducts of complex 2 perturb B-form DNA more severely than complex 1, however, without denaturing the double strand and significantly less than cisplatin. Circular and linear dichroism spectroscopies and viscosity measurements suggest that subtle differences exist between the intercalation modes and adduct geometries of the two complexes. The adducts formed by complex 2 most efficiently inhibit transcription of the damaged DNA by RNA polymerase II. Not only do complexes 1 and 2 cause less distortion to DNA than cisplatin, they also do not compromise the thermodynamic stability of the modified duplex. This leads to a decreased or negligible affinity of HMG domain proteins for the adducts formed by either Pt-acridine complex. In a DNA repair synthesis assay the lesions formed by complex 2 were repaired less efficiently than those formed by complex 1. These significant differences in DNA adduct formation, structure, and recognition between the two acridine complexes and cisplatin help to elucidate why compound 2 is highly active in cisplatin-resistant, repair proficient cancer cell lines.

• MeSH
• adukty DNA chemie   MeSH
• akridiny chemie   metabolismus   farmakologie   MeSH
• amidiny chemie   metabolismus   farmakologie   MeSH
• B-DNA chemie   metabolismus   MeSH
• cisplatina analogy a deriváty   chemie   metabolismus   farmakologie   MeSH
• DNA chemie   metabolismus   MeSH
• genetická transkripce účinky léků   MeSH
• HeLa buňky MeSH
• interkalátory chemie   metabolismus   farmakologie   MeSH
• kinetika MeSH
• konformace nukleové kyseliny účinky léků   MeSH
• lidé MeSH
• oprava DNA účinky léků   MeSH
• organoplatinové sloučeniny chemie   metabolismus   farmakologie   MeSH
• protein - isoformy metabolismus   MeSH
• protein HMGB1 metabolismus   MeSH
• protinádorové látky chemie   metabolismus   farmakologie   MeSH
• racionální návrh léčiv MeSH
• thiomočovina chemie   metabolismus   farmakologie   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• srovnávací studie MeSH
• Názvy látek
• adukty DNA MeSH
• akridiny MeSH
• amidiny MeSH
• B-DNA MeSH
• cisplatina MeSH
• DNA MeSH
• interkalátory MeSH
• organoplatinové sloučeniny MeSH
• protein - isoformy MeSH
• protein HMGB1 MeSH
• protinádorové látky MeSH
• thiomočovina MeSH