Fig. 2

Chloroquine and bortezomib restore doxorubicin accumulation, cell death and C/EBP-β LIP induction in Pgp-positive cells. Cells were cultured in the absence (ctrl) or presence of the lysosome inhibitor chloroquine (CQ; 1 μM), the proteasome inhibitor bortezomib (B; 1 μM), or their combination, for 24 h (panels a-c) or 72 h (panel b). Doxorubicin (dox; 5 μM) was added for additional 24 h (panels a-c) or in the last 48 h (panel b). a. Doxorubicin accumulation was measured in triplicates by a fluorimetric assay. Data are presented as means±SD (n = 3). *p < 0.01: treated cells vs ctrl cells; °p < 0.001: CQ + B-treated cells vs CQ/B-treated cells. b. Cell viability was measured in quadruplicates by a chemiluminescence-based assay. Data are presented as means±SD (n = 3). *p < 0.02: treated cells vs “- dox ctrl” cells; °p < 0.02: treated cells vs “+ dox ctrl” cells; ^#p < 0.005: CQ + B-treated cells vs CQ/B-treated cells. c. Whole cell lysates were probed with the indicated antibodies. The expression of β-tubulin was used as control of equal protein loading. The figure is representative of 1 out of 3 experiments