Objective The purpose of this study was to determine the effect of transient exposure to chemotherapeutic drugs on multidrug resistance of Tca8113 cells.Methods The MDR1 and MRP gene expressions in Tca8113 and K562/ADM cells lines were analyzed using reverse transcription polymerase chain reaction (RT-PCR), after the cells were treated with different cytotoxic drugs. The function and expressions of P-glycoprotein 170 and multidrug resistant associated protein were studied using fluorescence photometric assays.Results The inhibitive rate ofTca8113 cells was higher than that of K562/ADM, after exposure to chemothera- peutic drugs. The transient exposure to cytotoxic drugs weakly induced MDR1 and multidrug resistant associated protein expression in Tca8113 cells. The intracellular drug concentration in K562/ADMwas lower than that in Tca8113 cells.Conclusion Induction of MDR1 and multidrug resistant associated protein gene expression response to cytotoxic drugs may be related with the increased multi- drug resistance in drug-treated human tumor cells.
