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

Replacement of one ammine in clinically ineffective trans-[PtCl2(NH3)2] (transplatin) by a planar N-heterocycle, thiazole, results in significantly enhanced cytotoxicity. Unlike 'classical' cisplatin {cis-[PtCl2(NH3)2]} or transplatin, modification of DNA by this prototypical cytotoxic transplatinum complex trans-[PtCl2(NH3)(thiazole)] (trans-PtTz) leads to monofunctional and bifunctional intra or interstrand adducts in roughly equal proportions. DNA fragments containing site-specific bifunctional DNA adducts of trans-PtTz were prepared. The structural distortions induced in DNA by these adducts and their consequences for high-mobility group protein recognition, DNA polymerization and nucleotide excision repair were assessed in cell-free media by biochemical methods. Whereas monofunctional adducts of trans-PtTz behave similar to the major intrastrand adduct of cisplatin [J. Kasparkova, O. Novakova, N. Farrell and V. Brabec (2003) Biochemistry, 42, 792-800], bifunctional cross-links behave distinctly differently. The results suggest that the multiple DNA lesions available to trans-planaramine complexes may all contribute substantially to their cytotoxicity so that the overall drug cytotoxicity could be the sum of the contributions of each of these adducts. However, acquisition of drug resistance could be a relatively rare event, since it would have to entail resistance to or tolerance of multiple, structurally dissimilar DNA lesions.

• MeSH
• adukty DNA chemie   metabolismus   MeSH
• cisplatina chemie   toxicita   MeSH
• DNA biosyntéza   MeSH
• konformace nukleové kyseliny MeSH
• oprava DNA MeSH
• organoplatinové sloučeniny chemie   toxicita   MeSH
• proteiny s vysokou pohyblivostí metabolismus   MeSH
• protinádorové látky chemie   toxicita   MeSH
• reagencia zkříženě vázaná chemie   toxicita   MeSH
• thiazoly chemie   toxicita   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• adukty DNA MeSH
• cisplatina MeSH
• DNA MeSH
• organoplatinové sloučeniny MeSH
• proteiny s vysokou pohyblivostí MeSH
• protinádorové látky MeSH
• reagencia zkříženě vázaná MeSH
• thiazoly MeSH
• trans-(PtCl2(NH3)(thiazole)) MeSH Prohlížeč
• transplatin MeSH Prohlížeč

Bifunctional polynuclear platinum compounds represent a novel class of metal-based antitumor drugs which are currently undergoing preclinical development. A typical agent is [(trans-PtCl(NH(3))(2))(2)H(2)N(CH(2))(4)NH(2)]Cl(2) (1,1/t,t), which coordinates to bases in DNA and forms various types of covalent crosslinks. It also forms a 1,2-d(GpG) intrastrand adduct, the equivalent of the major DNA lesion of 'classical' cisplatin. In the present study differential scanning calorimetry and spectroscopic techniques were employed to characterize the influence of this crosslink on the thermal stability and energetics of 20 bp DNA duplexes site-specifically modified by 1,1/t,t. Thermal denaturation data revealed that the crosslink of 1,1/t,t reduced thermal and thermodynamical stability of the duplex noticeably more than that of 'classical' cisplatin. The energetic consequences of the intrastrand crosslink at the d(GG) site are discussed in relation to the structural distortions induced by this adduct in DNA and to its recognition and binding by HMG domain proteins. It has been suggested that the results of the present work are consistent with different DNA binding modes of cisplatin and polynuclear bifunctional DNA-binding drugs, which might be relevant to their distinct biological effectiveness.

• MeSH
• adukty DNA chemie   genetika   metabolismus   MeSH
• cirkulární dichroismus MeSH
• cisplatina metabolismus   MeSH
• denaturace nukleových kyselin MeSH
• diferenciální skenovací kalorimetrie MeSH
• DNA vazebné proteiny chemie   metabolismus   MeSH
• entropie MeSH
• guanin metabolismus   MeSH
• mutageneze cílená * MeSH
• oligodeoxyribonukleotidy chemie   genetika   metabolismus   MeSH
• platina chemie   metabolismus   MeSH
• proteiny s vysokou pohyblivostí chemie   metabolismus   MeSH
• protinádorové látky chemie   metabolismus   MeSH
• reagencia zkříženě vázaná chemie   metabolismus   MeSH
• sekvence nukleotidů MeSH
• spektrofotometrie ultrafialová MeSH
• teplota MeSH
• terciární struktura proteinů MeSH
• termodynamika MeSH
• vazebná místa MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adukty DNA MeSH
• cisplatina MeSH
• DNA vazebné proteiny MeSH
• guanin MeSH
• oligodeoxyribonukleotidy MeSH
• platina MeSH
• proteiny s vysokou pohyblivostí MeSH
• protinádorové látky MeSH
• reagencia zkříženě vázaná MeSH