Expression of organic anion transporter 1 or 3 in human kidney proximal tubule cells reduces cisplatin sensitivity

Abstract

Cisplatin is a cytostatic drug used for treatment of solid organ tumors. The main adverse effect is organic cation transporter 2 (OCT2)-mediated nephrotoxicity, observed in 30% of patients. The contribution of other renal drug transporters is elusive. Here, cisplatin-induced toxicity was evaluated in human-derived proximal tubule epithelial cells (ciPTEC) expressing renal drug transporters, including OCT2 and organic anion transporter 1 (OAT1) or 3 (OAT3). Parent ciPTEC demonstrated OCT2-dependent cisplatin toxicity (TC50 34±1 μM after 24 h exposure), as determined by cell viability. Over-expression of OAT1 and OAT3 resulted in reduced sensitivity to cisplatin (TC50 45±6 μM and 64±11 μM after 24 h exposure, respectively). This effect was independent of OAT-mediated transport, as the OAT-substrates probenecid and diclofenac did not influence cytotoxicity. Decreased cisplatin sensitivity in OAT-expressing cells associated directly with a trend towards reduced intracellular cisplatin accumulation, explained by reduced OCT2 gene expression and activity. This was evaluated by Vmax of the OCT2-model substrate ASP+ (23.5±0.1 min-1, 13.1±0.3 min-1 and 21.6±0.6 min-1 in ciPTEC-parent, ciPTEC-OAT1 and ciPTEC-OAT3, respectively). While gene expression of cisplatin efflux transporter multidrug and toxin extrusion 1 (MATE1) was 16.2±0.3 fold upregulated in ciPTEC-OAT1 and 6.1±0.7 fold in ciPTEC-OAT3, toxicity was unaffected by the MATE substrate pyrimethamine, suggesting that MATE1 does not play a role in the current experimental set-up. In conclusion, OAT expression results in reduced cisplatin sensitivity in renal proximal tubule cells, explained by reduced OCT2-mediated uptake capacity. In vitro drug-induced toxicity studies should consider models that express both OCT and OAT drug transporters.