Cisplatin up-regulates the in vivo biosynthesis and degradation of renal polyamines and c-Myc expression.

Time-dependent changes in polyamine metabolism and c-Myc expression are reported in kidney of mice treated with cisplatin, a widely used anticancer drug. We show that cisplatin significantly induces the expression of two enzymes critical to proper homeostasis of cellular polyamines, ornithine decarboxylase (ODC) and spermidine/spermine N1-acetyltransferase (SSAT). We also document the cross-talk between signalling pathway(s) induced by cisplatin injury to renal tubules and the testosterone/androgen receptor pathway. Their interaction results in a decrease in testosterone-induced ODC activity and ODC mRNA level, and in differential modulation of SSAT expression. Moreover, cisplatin and antifolate CB 3717, another nephrotoxic drug examined, severalfold up-regulate expression of c-Myc mRNA, albeit with different kinetics. However, cisplatin, contrary to CB 3717, does not induce renal hepatocyte growth factor (HGF)/c-Met expression being without effect on HGF mRNA level and significantly down-regulating c-Met transmembrane receptor message. In conclusion, these in vivo studies document significant cisplatin-induced modulation of polyamine biosynthesis/degradation and up-regulation of c-Myc expression, and suggest that c-Myc transcription factor is involved in the induction of ODC in kidney injured with antifolate, but not with cisplatin.