Targeting P-Glycoprotein: Nelfinavir Reverses Adriamycin Resistance in K562/ADR Cells

BACKGROUND/AIMS: The emergence of multidrug resistance (MDR) caused by P-glycoprotein (P-gp) overexpression is a serious obstacle to the treatment of chronic myelocytic leukemia. In recent years, some clinical trials have shown that nelfinavir (NFV), a traditional anti-HIV drug, has anti-cancer effects. Some researchers have also shown NFV might be a potential P-gp inhibitor. This study is aimed at investigating whether nelfinavir can act as an MDR-reversal drug and to clarify its molecular mechanism as well. METHODS: K562 and K562/ADR cell lines were applied in the study. Cytotoxicity was detected by CCK-8 reagents. Cell apoptosis was detected by flow cytometry and inverted fluorescence microscopy to detect the binding of apoptotic dyes to cells. Western blot was used to detect the expression of proteins. Drug-protein molecular docking simulation by using Sybyl-x 2.0 software. RESULTS: Non-toxic concentrations of NFV (1.25-5 μM) could reverse Adriamycin (ADR), colchicine, paclitaxel, and imatinib resistance of K562/ADR cells, with reversal indexes of up to 10.8, 7.4, 57, and 9.3, respectively. NFV inhibited P-gp efflux function, as evidenced by the significant increase in the intracellular accumulation of ADR and Rho-123, without affecting P-gp protein and mRNA expression levels. Further ATP content detection and molecular docking simulations showed that NFV could decrease intracellular ATP content and has a high affinity with the active functional regions of P-gp, respectively. When co-administered with ADR, NFV increased intracellular reactive oxygen species as well as blocked the ERK/Akt signaling pathway, leading to cell apoptosis. CONCLUSION: NFV inhibited P-gp function, decreased intracellular ATP content, and promoted cell apoptosis in K562/ADR cells, thereby reversing MDR. These findings encourage further animal and clinical MDR studies with a combination therapy consisting of NFV and chemotherapeutic drugs.