DNA damage and induction of apoptosis in pancreatic cancer cells by a new dinuclear bis(triazacyclonane) copper complex

The dinuclear copper(II) complex [Cu-2{bcmp(-H)}(mu-OH)](NO3)(2)center dot H2O (1, bcmp = 2,6-bis(1,4,7-triazacyclonon-1-ylmethyl)-4-methylphenol) has been synthesized and characterized by electrospray ionization mass spectrometry, potentiometric titration and cyclovoltammetry. The X-ray structure of the analogous perchlorate salt [Cu-2{bcmp(-H)}(mu-OH)](ClO4)(2)center dot 2.5H(2)O (2) was determined. Cytotoxicity studies showed very promising activity of 1 against various pancreatic tumor cell lines with IC50 values comparable or even lower than those of cisplatin. The Cu complex displayed low toxicity against a human non-tumor cell line (HEM 293) demonstrating selectivity for cancer cells. 1 converts supercoiled pUC19 plasmid DNA into the nicked form at micromolar concentrations in the absence of added reductants. A detailed kinetic study on the hydrolysis of the DNA model bis(2,4-dinitrophenyl) phosphate (BDNPP) has been performed. 1 hydrolyses BDNPP with a second order rate constant of 0.047 M s(-1) at pH 8 and 40 degrees C. Finally, single cell electrophoresis (comet assay) and fluorescence microscopy analysis showed that 1 interacts with cellular DNA and induces apoptotic cell death of Capan-1 pancreatic cancer cells. Western blotting analysis indicated that the Cu complex activates the p53 dependent pathway of apoptosis. (C) 2015 Elsevier Inc. All rights reserved.Financial supports from the European Commission and Science Foundation Ireland (Marie Curie FP7-IEF to D.M., Stokes Lectureship to A.E., grant no. 07/SK/B1225b) and from the University of Padova (Progetto di Ateneo CPDA121973/12) are gratefully acknowledged.peer-reviewe