The Copper Transporter CTR1 Regulates Cisplatin Uptake in Saccharomyces cerevisiae

Publisher Website
Google Scholar
Abstract
Resistance to cisplatin (DDP) is often accompanied by impaired accumulation in mammalian cells. The mechanism of impaired DDP accumulation is unknown, but copper uptake is diminished as well. We investigated the ability of the copper transporter CTR1to control the accumulation of DDP in Saccharomycescerevisiae. Parallel studies of copper and DDP cellular pharmacokinetics were carried out using an isogenic pair of wild-typeCTR1 and ctr1 knockout S. cerevisiae strains. Both copper and platinum accumulation increased linearly as a function of time and drug concentration in the parental cells. Deletion of CTR1 resulted in a 16-fold reduction in the uptake of copper and an 8-fold reduction in the uptake of DDP measured at 1 h. The CTR1-deficient cells accumulated 2.3-fold (p < 0.05) less platinum in their DNA and were 1.9-fold more resistant to the cytotoxic effect of DDP than the CTR1-replete cells. The kinetics of cellular copper accumulation were similar to those of DDP. Based on measurements of accumulation at 1 h, the Km for copper influx was 128.8 μM, and the Vmax was 169.5 ng/mg of protein/min; for DDP, the Km was 140.2 μM and the Vmax was 76.9 ng/mg of protein/min. DDP blocked the uptake of copper into the parental cells but notctr1-deficient cells. CTR1-deficient cells also demonstrated impaired accumulation of the DDP analogs carboplatin, oxaliplatin, and ZD0473 [cis-amminedichloro(2-methylpyridine) platinum (II)]. These results indicate that CTR1 function markedly influences the uptake of all of the clinically used platinum-containing drugs and suggest that this copper transporter may also transport DDP.