Ouabain-resistant non-small-cell lung-cancer cell line shows collateral sensitivity to cis-diamminedichloroplatinum(II) (CDDP).
We have reported that the cellular uptake of cis-diamminedichloroplatinum(II) (CDDP) was inhibited by an Na+,K(+)-adenosine triphosphatase (ATPase) inhibitor, ouabain, in a human non-small-cell lung-cancer cell line, PC-14, but not in its CDDP-resistant cell line, PC-14/CDDP. [3H]Ouabain binding of PC-14/CDDP was about 50% lower than that of PC-14. Accordingly, we speculated that a decrease in Na+,K(+)-ATPase activity in PC-14/CDDP might contribute to the decrease in cellular CDDP accumulation. To clarify the relationship between the activity or expression of Na+,K(+)-ATPase and cellular CDDP accumulation, we established an ouabain-resistant non-small-cell lung-cancer cell line (PC-14/OB300), which showed 1.9-fold resistance to the cytotoxicity of ouabain. Interestingly, this cell line was 4.2-fold more sensitive to CDDP than PC-14. The accumulation of CDDP in PC-14/OB300 was increased to 2.7-fold that in PC-14. This elevation of CDDP accumulation was not considered to be caused by increased passive diffusion, because the accumulation of CDDP in PC-14/OB300 was also inhibited by ouabain compared to PC-14. As one of the indices of Na+,K(+)-ATPase activity, we determined cellular 86Rb+ influx rates. The 86Rb+ influx rate was 1.5-fold higher in PC-14/OB300 and fell to 0.7-fold in PC-14/CDDP compared with PC-14. The mRNA expression of Na+,K(+)-ATPase was increased in PC-14/OB300 and decreased in PC-14/CDDP. There was no difference in cellular [3H]ouabain binding between PC-14/OB300 and PC-14. It is possible that Na+,K(+)-ATPase of PC-14/OB300 has a different affinity for ouabain from that of PC-14. Our results suggest that the enzyme activity or the level of expression of Na+,K(+)-ATPase may contribute to the cellular uptake of CDDP and determine the sensitivity to CDDP.
Ohmori
T
T
Pharmacology Division of National Cancer Center Research Institute, Tokyo, Japan.
Nishio
K
K
Ohta
S
S
Kubota
N
N
Adachi
M
M
Komiya
K
K
Saijo
N
N
D000230:Adenocarcinoma / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism; D015152:Blotting, Northern; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D002945:Cisplatin / Q000493:pharmacokinetics / Q000494:pharmacology*; D004351:Drug Resistance; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism; D010042:Ouabain / Q000378:metabolism / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D012413:Rubidium / Q000493:pharmacokinetics; D012414:Rubidium Radioisotopes; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D012414:Rubidium Radioisotopes; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D002945:Cisplatin