Objective: To study the relationship between the expression of multidrug resistance-associated protein (MRP) and P-glycoprotein (P-gp) and alteration of cell cycle during the process of drug resistance in lung cancer.
Methods: Lung adenocarcinoma cell line GLC-82 was treated with low concentration of adriamycin. At 0, 24, 48, 72 and 96 hr following adriamycin treatment, the expression of MRP and P-gp, and cell cycle were examined by bi-parameter flow cytometry.
Results: Treatment of GLC-82 cells with adriamycin at a final concentration of 0.05 microgram/ml resulted in progressive decrease in cells in G1 phase and increase in cells in S phase of the cell cycle. The expression level of P-gp was very low and showed little change with time. In contrast, MRP expression was significantly increased in a time-dependent manner, and was positively correlated with changes in S phase of the cell cycle.
Conclusion: MRP expression may play a major role in the development of resistance to adriamycin.