title: Synthesis, biological characterization and evaluation of molecular mechanisms of novel copper complexes as anticancer agents.
abstract: To overcome the hurdles of cisplatin, majorly its toxicity and resistance, there has been extensive search for alternative anti-cancer metal-based compounds. Here, three Cu(II)-complexes, Cu(Sal-Gly)(phen), Cu(Sal-Gly)(pheamine), Cu(Sal-Gly)(phepoxy) are characterized for their interaction with DNA, cytotoxicity and mechanism of action.
  
  
  
  The binding ability of the complexes to Calf-Thymus DNA was evaluated by competition fluorescence studies with thiazole-orange, UV-Vis and circular dichroism spectroscopic titrations. Cytotoxicity was evaluated by MTT analysis. The DNA damage was analyzed through cleavage of supercoiled DNA via agarose gel-electrophoresis, and 8-oxo-guanidine and ɣH2AX staining in cells. Apoptosis was detected via DNA condensation/fragmentation, mitochondrial membrane potential, Annexin V staining and caspase 3/7 activity. Formation of reactive oxygen species was determined by DCFDA- and GSSG/GSH-analysis.
  
  
  
  Binding constants to DNA were evaluated as 1.7×106(Cu(Sal-Gly)(phen)), 2.5×106(Cu(Sal-Gly)(pheamine)) and 3.2×105(Cu(Sal-Gly)(phepoxy)). All compounds induced DNA damage. Apoptosis was the main form of cell death. There was an increase in ROS, which is most likely responsible for the observed DNA-damage. Although the compounds were cytotoxic to all tested cancer cell lines, only Cu(Sal-Gly)(pheamine) displayed significantly lower toxicity towards non-cancer cells, its associated phenotypes differing from the other two Cu-complexes. Thus, Cu(Sal-Gly)(pheamine) was further assayed for molecular changes in response to drug treatment using a custom designed RT-qPCR array. Results showed that Harakiri was significantly upregulated. Presence of p53 was not required for apoptosis in response to Cu-complexes.
  
  
  
  These Cu-complexes, namely Cu(Sal-Gly)(pheamine), may be considered promising anticancer agents with activity in cancer cells even with deficient p53 status.
authors: TUBITAK, Marmara Research Center, Genetic Engineering and Biotechnology Institute, Gebze, Kocaeli, Turkey. Electronic address: ceyda.acilan@tubitak.gov.tr.
authors: Ceyda
authors: C
authors: Acilan
authors: Uludag University, Faculty of Arts and Sciences, Department of Biology, Bursa, Turkey.
authors: Buse
authors: B
authors: Cevatemre
authors: TUBITAK, Marmara Research Center, Genetic Engineering and Biotechnology Institute, Gebze, Kocaeli, Turkey.
authors: Zelal
authors: Z
authors: Adiguzel
authors: Uludag University, Faculty of Arts and Sciences, Department of Biology, Bursa, Turkey.
authors: Didem
authors: D
authors: Karakas
authors: Uludag University, Medical School, Department of Medical Biochemistry, Bursa, Turkey.
authors: Engin
authors: E
authors: Ulukaya
authors: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal.
authors: Nádia
authors: N
authors: Ribeiro
authors: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal. Electronic address: icorreia@tecnico.ulisboa.pt.
authors: Isabel
authors: I
authors: Correia
authors: Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal.
authors: João Costa
authors: JC
authors: Pessoa
mesh_terms: D000072283:A549 Cells; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002417:Cattle; D045744:Cell Line, Tumor; D003300:Copper / Q000737:chemistry*; D004247:DNA / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D045325:HCT116 Cells; D006367:HeLa Cells; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D017304:Annexin A5; D000970:Antineoplastic Agents; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D003300:Copper; D004247:DNA; C427203:calf thymus DNA; D053148:Caspase 3; D053179:Caspase 7
keywords: Anti-cancer drugs; Copper complexes; Interactions with DNA; Mechanism of cytotoxicity of Cu-compounds; Phenanthroline; Schiff base compounds