Contents lists available at ScienceDirect Journal of Inorganic Biochemistry journal homepage: www.elsevier.com/locate/jinorgbio Impact of the Cu(II) ions on the chemical and biological properties of goserelin – coordination pattern, DNA degradation, oxidative reactivity and in vitro cytotoxicity Paulina K. Walencik a , Kamila Stokowa-Sołtys a , Robert Wieczorek a , Urszula K. Komarnicka a , Agnieszka Kyzioł b , Małgorzata Jeżowska-Bojczuk a,⁎ a Faculty of Chemistry, University of Wroclaw, ul. F. Joliot-Curie 14, 50-383 Wroclaw, Poland b Faculty of Chemistry, Jagiellonian University, ul. R. Ingardena 3, 30-060 Kraków, Poland ARTICLE INFO Keywords: Goserelin Gonadotropin-releasing hormone Copper(II) complexes ABSTRACT Goserelin acetate (Gos) as a synthetic analog of the mammalian gonadotropin-releasing hormone (GnRH) is widely used in the treatment of sex hormone-related conditions. In this paper we present the chemical and biological aspects of its interaction with Cu(II) ions. The mode of Cu(II) binding and the thermodynamic stability of the obtained complexes were characterized by potentiometry, UV–Vis and CD spectroscopic methods. The DFT calculations were applied in order to investigate and confirm the molecular structure of the studied systems. The experimental and theoretical results clearly indicated the involvement of three nitrogens from the peptide and two oxygens from the acetate moieties in the Cu(II) coordination under physiological conditions. The in- vestigated metallopeptide caused single- and/or double cleavage of the sugar-phosphate backbone of the plasmid DNA in the reaction accompanied by endogenous substances such as hydrogen peroxide or ascorbic acid. The degradation of the DNA molecule occurred via the free radical mechanism. Calculations based on measured spectra allowed determining the kinetic parameters of % OH formation. The cytotoxic effects of Gos and its metallo-derivative were tested in vitro towards two cancer cell lines (A549 – human lung adenocarcinoma, CT26 – mouse colon carcinoma). 1. Introduction Despite their beneficial functions, estrogens, androgens and proges- terone also play a key role in the progression of the hormone-dependent forms of carcinoma [1,2]. Numerous studies have indicated the impact of the steroid hormones in the pathogenesis of certain types of diseases, in- cluding: prostate, breast, ovarian, endometrial and colon cancers, as well as endometrial hyperplasia [3,4]. For instance, about 70%–80% of breast cancers and approximately 70% of ovarian cancers are estrogen receptor-α and/or progesterone receptor positive. Similarly, the presence of androgen receptor is a defining feature of the prostate carcinoma [5–8]. Production of the gonadal hormones is controlled by the pulsatile secretion of GnRH (gonadotropin-releasing hormone), the primary regulator of the hy- pothalamus-pituitary-gonadal axis (HPG) [9,10]. The mammalian GnRH is a decapeptide with β-II-turn-type conformation. Its folded shape is pro- vided by the bend around the flexible Gly 6 residue and is essential for binding to the pituitary receptors (GnRHRs) [11]. The GnRH episodic secretion and activation of the endogenous GnRHRs are crucial for the normal reproductive function [12]. Apart from the nervous system, the receptors are highly expressed in human reproductive (breast, en- dometrium, ovary and prostate) and non-reproductive tissues (heart, adrenal, bladder, colon and lung), both in physiological and pathological conditions. Therefore, a novel modulatory role of GnRH in the context of tumors growth promotion, metastasis and angiogenesis has been reported [13–15]. Treatment of the hormone-dependent tumors is connected with the desensitization of the pituitary which suppress the secretion of GnRH and sex steroids, leading to pharmacological castration [15,16]. Comprehensive studies have indicated that metal ions may affect http://dx.doi.org/10.1016/j.jinorgbio.2017.07.016 Received 28 April 2017; Received in revised form 12 July 2017; Accepted 16 July 2017 ⁎ Corresponding author. E-mail address: malgorzata.jezowska-bojczuk@chem.uni.wroc.pl (M. Jeżowska-Bojczuk). Abbreviations: A549, human lung adenocarcinoma cell line; cAMP, cyclic adenosine monophosphate; CT26, mouse colon carcinoma cell line; DFT, Density Functional Theory; DMEM, Dulbecco's Modified Eagle Medium; FBS, fetal bovine serum; FDA, fluorescein diacetate; Gos, goserelin acetate; Glp, pyroglutamic acid; GnRH, gonadotropin-releasing hormone; GnRHR, gonadotrophin-releasing hormone receptor; HAc, acetic acid; HAsc, ascorbic acid; HPG, hypothalamus-pituitary-gonadal axis; ID, propidium iodide; IP3, inositol trisphosphate; MTT, 3- (4,5-dimethylthiazol-yl)-2,5-diphenyltetrazolium bromide; NDMA, N,N-dimethyl-4-nitrosoaniline; PBS, phosphate-buffered saline; ROS, reactive oxygen species; TRF, thyrotropin re- leasing hormone Journal of Inorganic Biochemistry 175 (2017) 167–178 Available online 21 July 2017 0162-0134/ © 2017 Elsevier Inc. All rights reserved. MARK