Study on the interactions between cisplatin and cadherin

Cisplatin is an important platinum drug in the chemotherapy of many malignant tumors in clinical application. It is well accepted that its main target is DNA molecule. However, recent studies have shown that platinum drugs may also act on some important functional proteins in the human body and have complicate effects on their efficacy. E-cadherin is newly discovered glycoproteins which have been regarded as the important signs of the occurrence and development of some tumors. In this study, the interactions between cisplatin and E-cadherin were explored by fluorescence spectroscopy and atomic force microscopy (AFM). The fluorescence spectroscopy results indicated that cisplatin can efficiently quench the fluorescence of E-cadherin, and the calculated binding constant Kb was 3.20x106 (25{degrees}C), 1.36 x106(31{degrees}C) and 8.22x105 L mol-1 (37{degrees}C). The thermodynamic parameters {Delta}H <0, {Delta}S <0, {Delta}G <0, reveal that the fluorescence quenching effect of cisplatin on E-cadherin is static quenching, which is dominated by hydrogen bond and van der Waals interaction. The AFM results revealed that there was a staggered interaction between the intermolecular domains of E-cadherin to form a long spherical chain structure. The addition of cisplatin could significantly affect the staggered effect of the E-cadherin molecules. All these results confirmed that there are strong interactions between cisplatin and cadherin.