LAUSR

Overcoming multidrug resistance (MDR) is a final goal of various recent studies, in which combination of different compounds and conventional chemotherapeutics results in circumventing MDR and hence cancer progression. Therefore, we aimed to investigate the effects of peroxisome proliferator‐activated receptors (PPARs)‐γ on MDR in doxorubicin‐resistant human myelogenous leukemia cells. The effect of doxorubicin on cell viability following treatment with ciglitazone was measured using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) assay. The activity of P‐glycoprotein (P‐gp), as one of the membrane transporters, was determined by the rhodamine 123 (Rho 123) assay. Quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) and Western blot were used for the measurement of P‐gp, and tensin homolog deleted on chromosome ten (PTEN) expression at mRNA and protein, respectively. For evaluation of doxorubicin (DOX)‐induced apoptosis by annexin V/PI staining was used. Ciglitazone significantly increases the cytotoxic effects of DOX. In addition, ciglitazone considerably decreased the expression levels and activity of P‐gp in DOX‐resistant K562 cells. Furthermore, upon the ciglitazone treatment, PTEN expression could be increased in K562/DOX cells in a PPARγ–dependent manner. Moreover, ciglitazone significantly enhanced DOX‐induced apoptosis in K562/DOX cells. The combination treatment of K562/DOX leukemia cancer cells with doxorubicin and ciglitazone might be an effective strategy in inducing apoptosis and reversing developed MDR, and more importantly decreasing the adverse side effects of these agents.