Cytotoxic efficacy of a novel dinuclear platinum(II) complex in human breast cancer cells

doi:10.1016/j.ejphar.2010.06.022

European Journal of Pharmacology

Volume 643, Issue 1, 15 September 2010, Pages 34-41

https://doi.org/10.1016/j.ejphar.2010.06.022 Get rights and content

Abstract

Evaluation of the cytotoxicity of a novel dinuclear platinum(II) complex of formula Pt₂(2-picoline)₄(berenil)₂ employing a MTT assay and inhibition of [³H]thymidine incorporation into DNA in both MDA-MB-231 and MCF-7 breast cancer cells demonstrated that the complex was more of a potent antiproliferative agent than cisplatin. The DNA-binding ability of Pt₂(2-picoline)₄(berenil)₂ estimated by an ethidium displacement assay indicated that the complex showed strong specificity for AT base pairs in the minor groove of DNA. Our study showed that Pt₂(2-picoline)₄(berenil)₂ was a potent catalytic inhibitor of topoisomerase II in opposition to cisplatin. Pt₂(2-picoline)₄(berenil)₂ was found to be a more active inhibitor of collagen biosynthesis than cisplatin. The up regulation of β₁-integrin and insulin-like growth factor I (IGF-I) receptor expression by the complex was shown to be accompanied by an increase in the expression of mitogen activated protein kinases in breast cell lines. The phenomenon was related to the increased expression of nuclear factor-kappaB (ΝF-κΒ) by Pt₂(2-picoline)₄(berenil)₂ as shown by the Western immunoblot analysis. Flow cytometric analysis and a fluorescent microscopy assay demonstrated that cell death appeared to result from apoptosis, with the possibility of secondary necrosis. The data presented suggested that Pt₂(2-picoline)₄(berenil)₂ impaired growth and metabolism of breast cancer cells more efficiently than cisplatin. These results indicated also the different properties of Pt₂(2-picoline)₄(berenil)₂ and cisplatin.

Introduction

Continuous efforts are being made to broaden the spectrum of activity and to improve the therapeutic properties of platinum-based agents. Many researchers have turned to multi-nuclear platinum complexes in an effort to overcome both natural and acquired resistance to cisplatin in human cancer cell lines (Wheate & Collins, 2005, Kasparkova et al., 2000, Farrell, 2004). The adducts formed by multi-nuclear platinum complexes are vastly different from the adducts formed by cisplatin. It has been suggested that the distortions induced by these complexes are only weakly recognized by DNA repair proteins (Wheate and Collins, 2005). The present study was undertaken to extend our recent findings related to the antineoplastic activity of novel dinuclear platinum(II) complexes with berenil and amine ligands (Bielawski et al., 2008). Berenil (1,3-bis(4′-amidinophenyl)triazene) can exhibit minor groove binding when it binds to both DNA and RNA duplexes, while also showing a preference for DNA duplexes with unobstructed minor grooves (Barcelo et al., 2001, Nguyen et al., 2004). In this study, Pt₂(2-picoline)₄(berenil)₂ (Fig. 1) was expected to be localized in the vicinity of the DNA, and the combined effect resulting from platination and minor groove binding might confer the cytotoxic activity of Pt₂(2-picoline)₄(berenil)₂. The antiproliferative activity of Pt₂(2-picoline)₄(berenil)₂ (Fig. 1) was examined in both MDA-MB-231 and MCF-7 human breast cancer cells. The mechanism of action of Pt₂(2-picoline)₄(berenil)₂ was studied by means of the relaxation assay of topoisomerase II, and ethidium displacement assay using calf thymus DNA, T4 coliphage DNA, poly(dA-dT)₂ and poly(dG-dC)₂.

One of the characteristic features of breast cancer cells is a deregulation of their interaction with extracellular matrix proteins (Mamoto and Ingber, 2009). Therefore, changes in the quantity, structure and distribution of collagens caused by anticancer agents may affect the metabolism and function of human breast cancer cells (Ioachim et al., 2002). Collagen biosynthesis and cell growth are stimulated by the insulin-like growth factor I (IGF-I). IGF-I, acting predominantly through the IGF-I receptor, has been demonstrated to stimulate proliferation, promote survival, enhance the metastatic potential of breast cancer cells (Gross and Yee, 2003) and prevent apoptosis (Kim et al., 2009). The effects of Pt₂(2-picoline)₄(berenil)₂ on collagen biosynthesis, β₁-integrin receptor, IGF-I receptor and the expression of several proteins in the signal generated through the receptors like: phosphorylated MAP-kinases (ERK1/2 and p38), phospho Akt, and ΝF-κΒ and the presence of apoptosis in human breast cancer cells were compared to those caused by cisplatin.

Section snippets

Materials

Dimethylformamide, K₂PtCl₄, KI, acetone, 2-picoline, diethyl ether, methanol, ethidium bromide, cisplatin, calf thymus DNA, T4 coliphage DNA, homopolymers poly(dA-dT)·poly(dA-dT), and poly(dG-dC)·poly(dG-dC), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and controlled process serum replacement I (CPSR1) were purchased from Sigma Chemical Co. (USA). Topoisomerase II, supercoiled pRYG DNA, and etoposide were purchased from TopoGEN (USA). Stock cultures of breast cancer

Results

The cell viability of breast cancer cells was measured by the method of Carmichael et al. (1987), using tetrazolinum salt in order to compare cytotoxicity of Pt₂(2-picoline)₄(berenil)₂ and cisplatin (Table 1). Pt₂(2-picoline)₄(berenil)₂ was found to decrease the number of viable cells in both estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) breast cancer cells. Although the cytotoxicity was concentration-dependent in both cell lines, it was more pronounced in

Discussion

The widespread clinical use of platinum compounds in cancer chemotherapy has prompted a search for new platinum agents (Wheate & Collins, 2005, Farrell, 2004). Promising platinum compounds still under development include the orally active satraplatin (JM-216), the sterically hindered AMD-473, and BBR3464, a polynuclear platinum with unusual DNA-binding characteristics (Choy, 2006, Beale et al., 2003, Kasparkova et al., 2002). The present study was undertaken to find out about the antineoplastic

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Molecular and Cellular PharmacologyCytotoxic efficacy of a novel dinuclear platinum(II) complex in human breast cancer cells

Abstract

Introduction

Section snippets

Materials

Results

Discussion

Biochim. Biophys. Acta

Farmaco

Drug Resist. Updat.

Trends Cell Biol.

Prog. Nucleic Res. Mol. Biol.

J. Inorg. Biochem.

Eur. J. Cancer

J. Biol. Chem.

Biochem. Biophys. Res. Commun.

Eur. J. Pharmacol.

Biophys. J.

Arch. Biochem. Biophys.

Biochem. Biophys. Res. Commun.

FEBS Lett.

J. Biol. Chem.

J. Immunol. Meth.

J. Biol. Chem.

A phase I clinical and pharmacological study of cis-diamminedichloro(2-methylpyridine) platinum II (AMD473)

Br. J. Cancer

DNA damage-processing pathways involved in the eukaryotic cellular response to anticancer DNA cross-linking drugs

Mol. Pharmacol.

Synthesis, DNA-binding affinity and cytotoxicity of the dinuclear platinum(II) complexes with berenil and amines ligands

Acta Pol. Pharm. Drug Res.

Molecular and Cellular Pharmacology
Cytotoxic efficacy of a novel dinuclear platinum(II) complex in human breast cancer cells