Role of human copper transporter Ctr1 in the transport of platinum-based antitumor agents in cisplatin-sensitive and cisplatin-resistant cells.
Recent studies have shown that the mammalian high-affinity copper transporter encoded by Ctr1 is involved in the uptake of cisplatin. However, the roles of hCtr1 in cisplatin-sensitive and cisplatin-resistant mammalian cells have not been investigated. Here, we show that, of five cisplatin-resistant cell lines, only one (SR2) exhibited substantial reduction in hCtr1 expression as compared with that in its sensitive line small cell lung cancers (SCLC), whereas copper efflux transporters ATP7A and ATP7B were not significantly altered. SR2 exhibited cross-resistance to carboplatin but not to oxaliplatin. Transfection of expression hemagglutinin-tagged hCtr1 cDNA into SCLC and SR2 cells enhanced the uptake of copper, cisplatin, carboplatin, and oxaliplatin, suggesting that hCtr1 transporter can transport these platinum-based drugs. Whereas increased sensitivities to all these platinum drugs were observed in hCtr1-transfected SCLC cells, increased sensitivities to cisplatin and carboplatin but not to oxaliplatin were observed in hCtr1-transfected SR2 cells. These results suggest that SR2 acquired an additional unique intracellular resistance mechanism to oxaliplatin. Finally, using hCtr1 deletion mutants, we showed that the NH2-terminal domain of hCtr1 was involved in transporting all these platinum-based antitumor agents. These results collectively show the importance of hCtr1 in the transport of platinum-based antitumor agents in cisplatin-sensitive and cisplatin-resistant variants.
Song
Im-Sook
IS
Department of Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
Savaraj
Niramol
N
Siddik
Zahid H
ZH
Liu
Peiman
P
Wei
Yingjie
Y
Wu
Chun Jing
CJ
Kuo
Macus Tien
MT
D000970:Antineoplastic Agents / Q000378:metabolism*; D001692:Biological Transport; D016190:Carboplatin / Q000378:metabolism; D018288:Carcinoma, Small Cell / Q000378:metabolism* / Q000473:pathology; D027682:Cation Transport Proteins / Q000502:physiology*; D002945:Cisplatin / Q000378:metabolism*; D003300:Copper / Q000378:metabolism*; D000079923:Copper Transporter 1; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology; D009944:Organoplatinum Compounds / Q000378:metabolism; D000077150:Oxaliplatin; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D027682:Cation Transport Proteins; D000079923:Copper Transporter 1; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D003300:Copper; D016190:Carboplatin; D002945:Cisplatin