Study of nucleic acids interactions with platinum basedcytostatics using biosensor

Introduction. Although platinum based cytostatic drugs have been successfully used in the chemotherapy of cancer for more than 30 years, its biochemical mechanism of action is still unclear. The current accepted opinion about cisplatin mechanism of action is that the drug induces its cytotoxic properties through binding to the nuclear DNA and subsequent interference with normal transcription, and/or DNA replication mechanisms. Objective. The aim of this paper was to study of binding of platinum cytostatic to DNA structure using of platinum biosensor. Materials and methods. Preparation of DNA adduct with cisplatin. dsDNA was modified in the presence NaClO4 by cisplatin for in the dark of a thermostatic box. Purification of DNA adduct. The obtained DNA adduct was purified by ultrafiltration. Preparation of biosensor. Metallothionein modified surface of hanging mercury drop electrode was used as a platinum biosensor. The platinum and Pt-DNA adduct were detected by adsorptive transfer stripping (AdTS) differential pulse voltammetry (DPV). AdTS DPV parameters: time of accumulation 240 s, time of interaction 400 s. Results. Here we studied a binding of different platinum based cytostatics (cisplatin, carboplatin and oxaliplatin) to genome DNA. The influence of concentration of DNA, temperature and ionic strength on yield of adducts has been described. Consequently, we used the suggested heavy metal biosensor to detection of platinum modified DNA. We found out that the highest yield of Pt-DNA adducts has been obtained, if we used 100 mg/ml DNA at temperature 37 C for 24 h, because the yield of the modification was very low up to 10 h. In addition, increasing ionic strength negatively influenced yield of the modification. We were able to analyse tens of nanograms of Pt-DNA adduct per millilitre using the biosensor. Conclusions. The suggested approach shows the possible way for simple, sensitive, and rapid detection and determination of cisplatin and Pt-DNA adducts. In addition, the biosensor could be applied to study of binding of platinum to DNA structure.