FIGURE 5.

Enforced MCL1 expression restores miR-26a-reversed multidrug resistance (MDR) in osteosarcoma MDR cells. (A,B) MDR KHOS cells stably infected with lentivirus-expressing vector or MCL1 were transfected with miR-26a mimics or NC mimics for 48 h. O/E, overexpression. (A) MCL1 expression was determined by Western blotting analysis. β-Actin was used as a loading control. Three independent experiments were conducted, and the representative images are shown. (B) Cells were then treated with doxorubicin, methotrexate, or cisplatin for another 48 h. The 50% cytotoxic concentration (IC₅₀) was evaluated by MTT assay. Each column represents the mean value from five replicates. Data were analyzed using Student’s t-test. **P < 0.01. (C,D) MDR U2OS cells were treated as in (A). MCL1 expression (C) and IC₅₀ value (D) were evaluated and analyzed as in (A,B).