title: Role of intercalation and redox potential in DNA photosensitization by ruthenium(II) polypyridyl complexes: assessment using DNA repair protein tests.
abstract: Here we report that the photoreactivity of ruthenium(II) complexes with nucleobases may not only be modulated by their photoredox properties but also by their DNA binding mode. The damage resulting from photolysis of synthetic oligonucleotides and plasmid DNA by [Ru(bpz)3](2+), [Ru(bipy)3](2+) and the two DNA intercalating agents [Ru(bpz)2dppz](2+) and [Ru(bipy)2dppz](2+) has been monitored by polyacrylamide gel electrophoresis and by tests using proteins involved in DNA repair processes (DNA-PKCs, Ku80, Ku70, and PARP-1). The data show that intercalation controls the nature of the DNA damage photo-induced by ruthenium(II) complexes reacting with DNA via an electron transfer process. The intercalating agent [Ru(bpz)2dppz](2+) is a powerful DNA breaker inducing the formation of both single and double (DSBs) strand breaks which are recognized by the PARP-1 and DNA-PKCs proteins respectively. [Ru(bpz)2dppz](2+) is the first ruthenium(II) complex described in the literature that is able to induce DSBs by an electron transfer process. In contrast, its non-intercalating parent compound, [Ru(bpz)3](2+), is mostly an efficient DNA alkylating agent. Photoadducts are recognized by the proteins Ku70 and Ku80 as with cisplatin adducts. This result suggests that photoaddition of [Ru(bpz)2dppz](2+) is strongly affected by its DNA intercalation whereas its photonuclease activity is exalted. The data clearly show that DNA intercalation decreases drastically the photonuclease activity of ruthenium(II) complexes oxidizing guanine via the production of singlet oxygen. Interestingly, the DNA sequencing data revealed that the ligand dipyridophenazine exhibits on single-stranded oligonucleotides a preference for the 5'-TGCGT-3' sequence. Moreover the use of proteins involved in DNA repair processes to detect DNA damage was a powerful tool to examine the photoreactivity of ruthenium(II) complexes with nucleic acids.
authors.affiliation: Université de Toulouse, Laboratoire des IMRCP, UMR 5623 CNRS, 118 Route de Narbonne, F-31062 Toulouse Cedex 9, France.
authors.forename: Etienne
authors.initials: E
authors.lastname: Gicquel
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Souchard
authors.forename: Fay
authors.initials: F
authors.lastname: Magnusson
authors.forename: Jad
authors.initials: J
authors.lastname: Chemaly
authors.forename: Patrick
authors.initials: P
authors.lastname: Calsou
authors.forename: Patricia
authors.initials: P
authors.lastname: Vicendo
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear / Q000378:metabolism; D010584:Bacteriophage phi X 174 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002417:Cattle; D056831:Coordination Complexes / Q000737:chemistry / Q000494:pharmacology*; D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007364:Intercalating Agents / Q000737:chemistry / Q000494:pharmacology*; D000072200:Ku Autoantigen; D010084:Oxidation-Reduction; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011485:Protein Binding; D011725:Pyridines / Q000737:chemistry / Q000494:pharmacology*; D012428:Ruthenium / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D034961:Antigens, Nuclear; D056831:Coordination Complexes; D004268:DNA-Binding Proteins; D007364:Intercalating Agents; D017319:Photosensitizing Agents; D011725:Pyridines; D012428:Ruthenium; D004247:DNA; C427203:calf thymus DNA; D011065:Poly(ADP-ribose) Polymerases; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen