Characterization of the antiproliferative potential and biological targets of a trans ketoimine platinum complex Joana Silva a , António Sebastião Rodrigues b , Paula A. Videira c , Jamal Lasri d , Adília Januário Charmier d,e , Armando J.L. Pombeiro d , Alexandra R. Fernandes a,d,⇑ a Departamento Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal b Human Molecular Genetics Research Centre (CIGMH), Department of Genetics, Faculty of Medical Sciences, Universidade Nova de Lisboa, Lisbon, Portugal c CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal d Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal e Faculdade de Engenharia, Universidade Lusófona de Humanidades e Tecnologias, Lisbon, Portugal article info Article history: Received 30 April 2014 Received in revised form 29 July 2014 Accepted 30 July 2014 Available online 13 August 2014 SI: Antitumor Active Organotin Compounds Keywords: Cancer Cisplatin Cytotoxicity DNA Selectivity trans-Pt abstract The characterization of the antiproliferative potential of the ketoimine platinum complex trans- [PtCl 2 {RC(@O)N@CN–(H)C(Me) 2 –CH 2 CH 2 } 2 ] (R = CH 2 CO 2 Me) is reported. It showed a higher cytotoxicity against HCT116 and HepG2 cancer cells (IC 50 values of 22.74 ± 0.04 lM and 22.08 ± 0.08 lM, respec- tively) compared to fibroblasts and a non-tumorigenic cell line. It was also observed a moderate ability of the complex to induce apoptosis in HCT116 cells, as observed by fluorescence microscopy and flow cytometry. The observed antiproliferative activities of the complex are mostly due to delay in the cell cycle progression. In vitro DNA interaction studies revealed a DNA affinity constant of 6.67  10 5 M 1 , suggesting a high affinity to DNA, by comparison to the value obtained for doxorubicin. A decrease in the electrophoretic mobility of the supercoiled plasmid DNA (pDNA) suggested the formation of com- plex-DNA adducts. However, the complex did not exhibit relevant genotoxicity in V79 cells. Proteomic assays demonstrated that the ketoimine Pt(II) complex promotes an overexpression of two negative cell cycle regulators, PA2G4 and 14-3-3r, and PHB, and a decrease in expression of VDAC1 and HSP90B, prob- ably associated with the antiproliferative potential. The ketoimine Pt(II) complex is able to trigger an overexpression of cytoskeleton-associated proteins in agreement with its ability to maintain cell struc- ture, and an overexpression of oxidative stress enzymes, coping with the induction of ROS formation, observed by in vitro EMSA assays. In conclusion, the ketoimine Pt(II) complex is an antiproliferative agent with potential to be used against cancer cells. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction The chemotherapeutic agents applied today in the clinic present two major drawbacks: the development of high toxicity towards healthy tissues and the emergence of intrinsic and acquired drug resistance. These problems trigger the search for novel compounds with greater cytotoxicity against tumor cells and reduced side effects. N-platinum complexes containing heterocyclic groups are widely used in medicine due to their biological activities. The three approved platinum based complexes, cisplatin, oxaliplatin, and carboplatin, play a major role in cancer chemotherapy [1–3]. The first complex of the class, cis-[PtCl 2 (NH 3 )] 2 (cisplatin), exerts its antitumor activity by interacting with DNA [4,5]. Cisplatin directly binds to the DNA molecule of tumor cells, forming a cross-link that leads to the arrest of DNA synthesis and replication and also its transcription [6,7]. Bi-functional adducts between two adjacent bases in the same DNA strand are the main type of adducts induced by cisplatin, accounting for more than 90% of all adducts [6,8,9]. In rapidly dividing cells, i.e. cancer cells, cisplatin can also induce DNA damage, which ultimately leads to irreversible cellular injury and death by apoptosis [6,7]. Apoptosis can be induced by the acti- vation of various signal transduction pathways that includes cal- cium signaling, death receptor signaling, and the activation of mitochondrial pathways [10]. However, despite its broader appli- cation there are several drawbacks of cisplatin such as undesirable side effects, mutagenic effects, and the occurrence of drug resistance [1,6,11–14]. These problems triggered the development of a high number of cisplatin’s analogues, in order to find new http://dx.doi.org/10.1016/j.ica.2014.07.067 0020-1693/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author at: Departamento Ciências da Vida, Faculdade Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal. Tel./fax: +351 21 294 85 30. E-mail address: ma.fernandes@fct.unl.pt (A.R. Fernandes). Inorganica Chimica Acta 423 (2014) 156–167 Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica