Assessment of cisplatin-induced nephrotoxicity by microarray technology

Microarrays are a new technology used to study global gene expression and t o decipher biological pathways. In the current study, microarrays were used to examine gene expression patterns associated with cisplatin-mediated nep hrotoxicity. Sprague-Dawley rats received either single or seven daily ip d oses of cisplatin (0.5 or 1 mg/kg/day) or the inactive isomer transplatin ( 1 or 3 mg/kg/day). Histopathological evaluation revealed renal proximal tub ular necrosis in animals that received cisplatin for 7 days, but no hepatot oxic findings. Microarray analyses were performed using rat specific arrays containing 250 toxicity-related genes. Prominent gene expression changes w ere observed only in the kidneys of rats that received cisplatin for 7 days . Mechanistically, the gene expression pattern elicited by cisplatin (e.g., Bax up arrow and SMP-30 down arrow) suggested the occurrence of apoptosis and the perturbation of intracellular calcium homeostasis. The induction of multidrug resistance genes (MDR1 up arrow, P-gp up arrow) and tissue remod eling proteins (clusterin up arrow, IGFBP-1 up arrow, and TIMP-1 up arrow) indicated the development of cisplatin resistance and tissue regeneration. Select gene expression changes were further confirmed by TaqMan (R) analyse s. Gene expression changes were not observed in the liver following cisplat in administration. In contrast to these in vivofindings, studies using NRK- 52E kidney epithelial cells and clone-9 liver cells suggested that liver ce lls were more sensitive to cisplatin treatment. The discrepancies between t hein vivoandin vitroresults suggest that caution should be taken when extra polating data fromin vivotoin vitrosystems. Nonetheless, the current study elucidates the biochemical pathways involved in cisplatin toxicity and demo nstrates the utility of microarrays in toxicological studies.