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

Downstream processes that discriminate between DNA adducts of a third generation platinum antitumor drug oxaliplatin and conventional cisplatin are believed to be responsible for the differences in their biological effects. These different biological effects are explained by the ability of oxaliplatin to form DNA adducts more efficient in their biological effects. In this work conformation, recognition by HMG domain protein and DNA polymerization across the major 1,2-GG intrastrand cross-link formed by cisplatin and oxaliplatin in three sequence contexts were compared with the aid of biophysical and biochemical methods. The following major differences in the properties of the cross-links of oxaliplatin and cisplatin were found: i), the formation of the cross-link by oxaliplatin is more deleterious energetically in all three sequence contexts; ii), the cross-link of oxaliplatin bends DNA slightly but systematically less in all sequence contexts tested; iii), the affinity of HMG domain protein to the cross-link of oxaliplatin is considerably lower independent of the sequence context; and iv), the Klenow fragment of DNA polymerase I pauses considerably more at the cross-link of oxaliplatin in all sequence contexts tested. We have also demonstrated that the chirality at the carrier ligand of oxaliplatin can affect its biological effects.

• MeSH
• adukty DNA chemie   ultrastruktura   MeSH
• guanin chemie   MeSH
• konformace nukleové kyseliny MeSH
• organoplatinové sloučeniny chemie   MeSH
• oxaliplatin MeSH
• párování bází MeSH
• protinádorové látky chemie   MeSH
• reagencia zkříženě vázaná MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adukty DNA MeSH
• guanin MeSH
• organoplatinové sloučeniny MeSH
• oxaliplatin MeSH
• protinádorové látky MeSH
• reagencia zkříženě vázaná MeSH

1,2-GG intrastrand cross-links formed in DNA by the enantiomeric complexes [PtCl(2)(R,R-2,3-diaminobutane (DAB))] and [PtCl(2)(S,S-DAB)] were studied by biophysical methods. Molecular modeling revealed that structure of the cross-links formed at the TGGT sequence was affected by repulsion between the 5'-directed methyl group of the DAB ligand and the methyl group of the 5'-thymine of the TGGT fragment. Molecular dynamics simulations of the solvated platinated duplexes and our recent structural data indicated that the adduct of [PtCl(2)(R,R-DAB)] alleviated this repulsion by unwinding the TpG step, whereas the adduct of [PtCl(2)(S,S-DAB)] avoided the unfavorable methyl-methyl interaction by decreasing the kink angle. Electrophoretic retardation measurements on DNA duplexes containing 1,2-GG intrastrand cross-links of Pt(R,R-DAB)(2+) or Pt(S,S-DAB)(2+) at a CGGA site showed that in this sequence both enantiomers distorted the double helix to the identical extent similar to that found previously for the same sequence containing the cross-links of the parent antitumor cis-Pt(NH(3))(2)(2+) (cisplatin). In addition, the adducts showed similar affinities toward the high-mobility-group box 1 proteins. Hence, whereas the structural perturbation induced in DNA by 1,2-GG intrastrand cross-links of cisplatin does not depend largely on the bases flanking the cross-links, the perturbation related to GG cross-linking by bulkier platinum diamine derivatives does.

• MeSH
• adukty DNA chemie   genetika   MeSH
• biofyzika MeSH
• biofyzikální jevy MeSH
• cisplatina analogy a deriváty   chemie   MeSH
• konformace nukleové kyseliny MeSH
• ligandy MeSH
• molekulární modely MeSH
• protein HMGB1 chemie   MeSH
• reagencia zkříženě vázaná MeSH
• retardační test MeSH
• sekvence nukleotidů MeSH
• stereoizomerie MeSH
• techniky in vitro MeSH
• termodynamika MeSH
• vodíková vazba MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adukty DNA MeSH
• cisplatin-DNA adduct MeSH Prohlížeč
• cisplatina MeSH
• ligandy MeSH
• protein HMGB1 MeSH
• reagencia zkříženě vázaná MeSH