In vitro gene expression analysis of nephrotoxic drugs in rat primary renal cortical tubular cells.

Rat primary renal cortical tubular cells were exposed to seven test substances, some with, and some without, known direct renal tubular cell toxicity. Cells were exposed to the substances at either one-third or one-tenth of the TC50 for cytotoxicity for 6 h or 24 h, so as not to induce cytotoxicity but to cause some transcriptional changes. Transcriptional profiles were investigated by using the Affymetrix Rat Toxicology U34 arrays, containing probes for more than 850 genes and ESTs. Four direct toxicants, cisplatin (CDDP), its less nephrotoxic analogue carboplatin (CBDCA), cephaloridine and gentamicin, were grouped together in a hierarchical clustering. In addition, the four direct toxicants affected more than 32 transcripts at their subcytotoxic concentrations at either 6 h or 24 h exposure. On the other hand, diclofenac, cyclosporine A and zinc, which are not considered to be directly toxic to tubules, affected less than 12 transcripts. Decreased Map3k12 and increased Hmox1 were commonly observed among the four direct toxicants, which appeared to be responses to cellular damage. Two platinum complexes, CDDP and CBDCA, induced similar changes, regardless of exposure duration or concentration. The types of transcriptional changes observed in this study were consistent with previously reported in vivo data, although there were some differences. These observations suggest that an in vitro gene expression analysis approach using GeneChip is feasible for screening for direct tubular toxicity of drugs and may help to clarify the underlying mechanisms of tubular toxicity.