Decreased cisplatin uptake by resistant L1210 leukemia cells.

Cisplatin resistance remains poorly understood compared to other forms of anti-neoplastic drug resistance. In this report radiolabeled cisplatin and rapid separation techniques were used to compare drug uptake by L1210 leukemia cells that are sensitive (K25) or resistant (ZCR9) to cisplatin. Uptake of cisplatin by both cell lines was linear without saturation kinetics up to 100 microM. The resistant ZCR9 cells had 36-60% reduced drug uptake as compared to its sensitive parent line, K25. In contrast, there was no difference in the rate of efflux. We conclude that a decreased rate of uptake is one possible mechanism of cellular cisplatin resistance.