title: Studies on the mechanism of action of antitumor bis(aminophenolate) ruthenium(III) complexes.
abstract: Two recently published Ru(III) complexes bearing (N2O2) tetradentate bis(aminophenolate) ligands, formulated as [Ru(III)(salan)(PPh3)Cl] (salan is the tetradentate ligand 6,6'-(1S,2S)-cyclohexane-1,2-diylbis(azanediyl)bis(methylene)bis(3-methoxyphenol) in complex 1, or 2,2'-(1S,2S)-cyclohexane-1,2-diylbis(azanediyl)bis(methylene)bis(4-methoxyphenol) in complex 2; PPh3is triphenylphosphane) and found very active against ovarian and breast adenocarcinoma human cells were studied to outline their antitumor mode of action. The human cisplatin-sensitive ovarian adenocarcinoma line A2780 was used herein as the cell model. At a 24h challenge (similarly as found before for 72h) both complexes are active, their cytotoxicity being comparable to that of cisplatin in the same conditions. As a possible target in the cell for their action, the interaction of 1 and 2 with DNA was assessed through displacement of well-established DNA fluorescent probes (ethidium bromide, EB, and 4',6-diamidino-2-phenylindole, DAPI) through steady-state and time-resolved fluorescence spectroscopy. The whole emission spectra were analyzed globally for the binary DNA-probe and ternary DNA-probe-Ru(III) complex systems. Both Ru(III) complexes can displace EB and bind to DNA with similar and moderate strong affinity with conditional stability constants of logK'=(5.05±0.01) for 1 and logK'=(4.79±0.01) for 2. The analysis of time-domain fluorescence intensity decays confirmed both qualitatively and quantitatively the model used to describe the binding and competition processes. Cell studies indicated that apoptosis is the major mechanism of cell death for both complexes, with 2 (the more active complex) promoting that process more efficiently than 1. Transmission electron micrographs revealed clear alterations on intracellular organization consistent with the induction of programmed cell death processes.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary; MTA-SZTE Bioinorganic Chemistry Research Group, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Dömötör
authors.affiliation: Centro de Química e Bioquímica (CQB), Faculdade de Ciências, ULisboa, Campo Grande, Lisbon, Portugal.
authors.forename: Rodrigo F M
authors.initials: RF
authors.lastname: de Almeida
authors.affiliation: Centro de Química Estrutural (CQE), Faculdade de Ciências, ULisboa, Campo Grande, Lisbon, Portugal.
authors.forename: Leonor
authors.initials: L
authors.lastname: Côrte-Real
authors.affiliation: Centro de Química Estrutural (CQE), Faculdade de Ciências, ULisboa, Campo Grande, Lisbon, Portugal; Centro de Química Estrutural (CQE), Instituto Superior Técnico, ULisboa, Av. Rovisco Pais, 1, Lisbon, Portugal.
authors.forename: Cristina P
authors.initials: CP
authors.lastname: Matos
authors.affiliation: Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, ULisboa, Estrada Nacional 10, Bobadela, Loures, Portugal.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Marques
authors.affiliation: Centro de Investigação Interdisciplinar Egas Moniz (CiiEM), Quinta da Granja, Monte da Caparica, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Matos
authors.affiliation: Centro de Química e Bioquímica (CQB), Faculdade de Ciências, ULisboa, Campo Grande, Lisbon, Portugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Real
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary; MTA-SZTE Bioinorganic Chemistry Research Group, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Kiss
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
authors.forename: Éva Anna
authors.initials: ÉA
authors.lastname: Enyedy
authors.affiliation: Centro de Química Estrutural (CQE), Faculdade de Ciências, ULisboa, Campo Grande, Lisbon, Portugal.
authors.forename: M
authors.initials: M
authors.lastname: Helena Garcia
authors.affiliation: Centro de Química Estrutural (CQE), Faculdade de Ciências, ULisboa, Campo Grande, Lisbon, Portugal. Electronic address: isabel.tomaz@ciencias.ulisboa.pt.
authors.forename: Ana Isabel
authors.initials: AI
authors.lastname: Tomaz
mesh_terms: D000627:Aminophenols / Q000737:chemistry* / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D004247:DNA / Q000737:chemistry; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D012428:Ruthenium / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000627:Aminophenols; D000970:Antineoplastic Agents; D056831:Coordination Complexes; D012428:Ruthenium; D004247:DNA
keywords: Antitumor; Apoptosis; Cell cycle arrest; Cell morphology; DNA binding constants; Ru(III)-bis(aminophenolate) complexes; Ru(III)-salan complexes