Chloroquine potentiates cisplatin cytotoxicity against A549cisR lung cancer cells in an LMP-mediated manner.

<p><b>(A)</b> A549cisR cells treated overnight with cisplatin and chloroquine. Next day, cytosolic (cy), total protein (T) and lysosomal (ly) fractions were separated by ultracentrifugation and lysates were loaded on SDS/PAGE gels. Upon transfer, membranes were probed with specific antibodies against cathepsin D (cath D), LAMP-1 (lysosomes) and α-tubulin (cytosolic marker). <b>(B)</b> A549cisR cells were treated with 1ûS, chloroquine 100 μM, cisplatin 100 μM, or combination with or without pretreatment with E64 (10 μM). Cell viability was measured with CellTiter-Blue^®. X-axis, represent the % cell viability at 48 hours (T48/T1) normalized to the negative control 1ûS. *p<0.05 treatment condition versus 1ûS. <b>(C)</b> A549cisR cells were treated with different concentrations of cisplatin (cisPt) and CQ and pre-treated or not with E64 (10 μM) for 2 hours. Combination index (CI) was calculated as the ratio of the actual cell viability to the expected cell viability. Graph bars show the Mean±SEM from three independent experiments. *p<0.05 cells pre-exposed to E64 versus cells not pre-exposed to E64 and treated with the same concentration of cisplatin and chloroquine.