The use of the effective antineoplastic agent cisplatin is limited by its serious side effects , such as oto-and nephrotoxicity. Ototoxicity is a problem of special importance in children , because deafness hampers their language and psychosocial development. Recently , organic cation transporters (OCTs) were identified in vitro as cellular uptake mechanisms for cisplatin. In the present study , we investigated in an in vivo model the role of OCTs in the development of cisplatin oto-and nephrotoxicity. The functional effects of cisplatin treatment on kidney (24 hours excretion of glucose , water , and protein) and hearing (auditory brainstem response) were studied in wildtype and OCT1/2 double-knockout (KO) mice. No sign of ototoxicity and only mild nephrotoxicity were observed after cisplatin treatment of knockout mice. Comedication of wild-type mice with cisplatin and the organic cation cimetidine protected from ototoxicity and partly from nephrotoxicity. For the first time we showed that OCT2 is expressed in hair cells of the cochlea. Furthermore , cisplatin-sensitive cell lines from pediatric tumors showed no expression of mRNA for OCTs , indicating the feasibility of therapeutic approaches aimed to reduce cisplatin toxicities by competing OCT2-mediated cisplatin uptake in renal proximal tubular and cochlear hair cells. These findings are very important to establish chemotherapeutical protocols aimed to maximize the antineoplastic effect of cisplatin while reducing the risk of toxicities.

Cis-platin is an effective anti-neoplastic agent, but it is also highly nephrotoxic. Here, we clearly identify the human organic cation transporter 2 (hOCT2) as the critical transporter for cis-platin nephrotoxicity in isolated human proximal tubules and offer a potential mechanism for reducing nephrotoxicity in clinical practice. Interaction of cis-platin with hOCT2 in kidney or hOCT1 in liver was investigated with the fluorescent cation 4-[4-(dimethyl-amino)styril]-methylpyridinium in stably transfected HEK293 cells and for the first time in tissues physiologically expressing these transporters, human proximal tubules, and human hepatocyte couplets. Cis-platin (100 micromol/L) inhibited transport via hOCT2-HEK293 but not hOCT1-HEK293. In human proximal tubules cis-platin competed with basolateral organic cation transport, whereas it had no effect in tubules from a diabetic kidney or in hepatocytes. In hOCT2-HEK293 cells treated for 15 hours, incubation with cis-platin induced apoptosis, which was completely suppressed by contemporaneous incubation with the hOCT2 substrate cimetidine (100 micromol/L). These findings demonstrate that uptake of cis-platin is mediated by hOCT2 in renal proximal tubules, explaining its organ-specific toxicity. A combination of cis-platin with other substrates that compete for hOCT2 offers an effective option to decrease nephrotoxicity in the clinical setting.

Drug ototoxicity limits the quality of life of patients after treatment, having serious consequences, especially for psychosocial development of children. Although the ototoxicity of many drugs resolves after treatment discontinuation, the use of platinum derivatives and aminoglycosides is associated with permanent hearing loss. In this review, we have listed ototoxic drugs and the mechanisms by which they damage the ears. Moreover, possible protective strategies and important methods for early detection of ototoxic effects are discussed.