Abstract: Objective To investigate the effect of chloroquine in reversing multidrug resistance (MDR) of HNE1/DDP cell line
and explore the mechanism. Methods MTT assay was used to detect the cell viability of HNE1 and HNE1/DDP after
exposure to different concentrations of DDP (2, 4, 8, 16 and 32 μmol/L) and different concentrations of chloroquine (5, 10, 20,
40, and 80 μmol/L). q-PCR was used to assess the expression of MDR1 mRNA and Western blotting was employed to detect
P-glycoprotein (P-gp) expression in HNE1 and HNE1/DDP cells exposed to 5 and 10 μmol/L chloroquine. The cell apoptosis
rate of HNE1 and HNE1/DDP cells exposed to 10 and 20 μmol/L chloroquine was determined by PI assay. Results
Chloroquine exposure caused dose-dependent suppression of the proliferation in both HNE1 and HNE1/DDP cells, and
significantly reversed multidrug resistance in HNE1/DDP cells. The expressions of MDR1 mRNA and P-gp protein were
significantly lowered in the cells treated with chloroquine. Conclusion Chloroquine can reverse multidrug resistance in HNE1/
DDP cells possibly through down-regulation of MDR1 and inhibition of P-gp protein.