Study of interrelations between resistance to cisplatin and composition of low molecular weight thiols in murine leukemia L1210 cell lines

Abstract

Cis-dichlorodiammineplatinum (II), commonly known as cisplatin, is a widely used anticancer drug. However, the therapeutic efficacy of the drug is limited due to various dose-limiting side effects and development of acquired resistance. The resistance of malignant cells to cisplatin may be connected to elevated concentration of cellular thiols. To verify this hypotheses, we compared the concentrations of low weight cellular thiols, metallothionein (MT) and glutathione (reduced, GSH and oxidized, GSSG) and also the metal-binding properties of MT in the two cell lines, known to be resistant (L1210R) or sensitive (L1210S) to cisplatin. It was established that R-cells were characterised by higher concentrations of MTs and GSH, higher ratio of copper in the composition of MTs in comparison to zinc than S-cells. The treatment by cisplatin provoked the decrease of the GSSG concentration only in the S-cells without the changes in GSH concentration. Hence, R-cells insensitivity to cisplatin can be related to higher levels of MTs and GSH. Reported for the first time peculiar metal composition of MTs in R-cells can also give an advance to these cells by particular oxidizing properties of copper-MT. These specific characteristics of thiols in malignant cells could be useful for the indication of cisplatin resistance.