The trinuclear BBR3464 ([{trans-PtCl(NH(3))(2)}(2)µ-(trans-Pt(NH(3))(2)(H(2)N(CH(2))(6)NH(2))(2))](4+)) belongs to the polynuclear class of platinum-based anticancer agents. DNA adducts of this complex differ significantly in structure and type from those of clinically used mononuclear platinum complexes, especially, long-range (Pt, Pt) intrastrand and interstrand cross-links are formed in both 5'-5' and 3'-3' orientations. We show employing short oligonucleotide duplexes containing single, site-specific cross-links of BBR3464 and gel electrophoresis that in contrast to major DNA adducts of clinically used platinum complexes, under physiological conditions the coordination bonds between platinum and N7 of G residues involved in the cross-links of BBR3464 can be cleaved. This cleavage may lead to the linkage isomerization reactions between this metallodrug and double-helical DNA. Differential scanning calorimetry of duplexes containing single, site-specific cross-links of BBR3464 reveals that one of the driving forces that leads to the lability of DNA cross-links of this metallodrug is a difference between the thermodynamic destabilization induced by the cross-link and by the adduct into which it could isomerize. The rearrangements may proceed in the way that cross-links originally formed in one strand of DNA can spontaneously translocate from one DNA strand to its complementary counterpart, which may evoke walking of the platinum complex on DNA molecule.

• MeSH
• adukty DNA chemie   MeSH
• diferenciální skenovací kalorimetrie MeSH
• DNA chemie   MeSH
• organoplatinové sloučeniny chemie   MeSH
• protinádorové látky chemie   MeSH
• reagencia zkříženě vázaná chemie   MeSH
• termodynamika MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adukty DNA MeSH
• BBR 3464 MeSH Prohlížeč
• DNA MeSH
• organoplatinové sloučeniny MeSH
• protinádorové látky MeSH
• reagencia zkříženě vázaná MeSH

We studied the effect of antitumor cisplatin and inefficient transplatin on the structure and stability of G quadruplexes formed by the model human telomere sequence 5'-GGG(TTAGGG)(3)-3' using circular dichroism, UV-monitored thermal denaturation, and gel electrophoresis. In addition, to investigate whether there is a connection between the ability of cisplatin or transplatin to affect telomerase activity and stability of G quadruplexes, we also used a modified telomere repeat amplification protocol assay that uses an oligonucleotide substrate for telomerase elongation susceptible to forming a G quadruplex. The results indicate that cisplatin is more efficient than transplatin in disturbing the quadruplex structure, thereby precluding telomeric sequences from forming quadruplexes. On the other hand, the results of this work also demonstrate that in absence of free platinum complex, DNA adducts of antitumor cisplatin inhibit telomerase catalysis, so the mechanism underlying this inhibition does not involve formation of the G quadruplexes which are not elongated by telomerase.

• MeSH
• adukty DNA účinky léků   genetika   metabolismus   MeSH
• biokatalýza MeSH
• cirkulární dichroismus MeSH
• cisplatina chemie   farmakologie   MeSH
• denaturace nukleových kyselin MeSH
• elektroforéza v polyakrylamidovém gelu MeSH
• G-kvadruplexy účinky léků   MeSH
• lidé MeSH
• protinádorové látky chemie   farmakologie   MeSH
• sekvence nukleotidů MeSH
• spektrofotometrie ultrafialová MeSH
• techniky amplifikace nukleových kyselin MeSH
• telomerasa antagonisté a inhibitory   metabolismus   MeSH
• telomery chemie   genetika   MeSH
• tranzitní teplota MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adukty DNA MeSH
• cisplatina MeSH
• protinádorové látky MeSH
• telomerasa MeSH
• transplatin MeSH Prohlížeč