Cysteines Introduced into Extracellular Loops 1 and 4 of Human P-Glycoprotein That Are Close Only in the Open Conformation Spontaneously Form a Disulfide Bond That Inhibits Drug Efflux and ATPase Activity

Multidrug resistance (MDR) is a complicated ever-changing problem in cancer treatment, and P-glycoprotein (P-gp), a drug efflux pump, is regarded as the major cause. In the way of developing P-gp inhibitors, natural products such as phenolic acids have gotten a lot of attention recently. The aim of the present study was to investigate the modulating effects and mechanisms of caffeic acid on human P-gp, as well as the attenuating ability on cancer MDR. Calcein-AM, rhodamine123, and doxorubicin were used to analyze the interaction between caffeic acid and P-gp, and the ATPase activity of P-gp was evaluated as well. Resistance reversing effects were revealed by SRB and cell cycle assay. The results indicated that caffeic acid uncompetitively inhibited rhodamine123 efflux and competitively inhibited doxorubicin efflux. In terms of P-gp ATPase activity, caffeic acid exhibited stimulation in both basal and verapamil-stimulated activity. The combination of chemo drugs and caffeic acid resulted in decreased IC50 in ABCB1/Flp-InTM-293 and KB/VIN, indicating that the resistance was reversed. Results of molecular docking suggested that caffeic acid bound to P-gp through GLU74 and TRY117 residues. The present study demonstrated that caffeic acid is a promising candidate for P-gp inhibition and cancer MDR attenuation.

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THE MODULATION OF DRUG EFFLUX TRANSPORTER BY CURCUMIN IN MCF7 BREAST CANCER CELLS AFTER REPEATED EXPOSURE OF ENDOXIFEN AND ESTRADIOL

International Journal of Applied Pharmaceutics ◽

10.22159/ijap.2018.v10s1.21 ◽

2018 ◽

Vol 10 (1) ◽

pp. 102

Author(s):

Robby Hertanto ◽

Wilson Bastian ◽

Paramita . ◽

Melva Louisa

Keyword(s):

Breast Cancer ◽

Cell Viability ◽

Mrna Expression ◽

Rna Extraction ◽

Efflux Transporters ◽

Drug Efflux ◽

Mcf7 Cells ◽

Total Rna ◽

P Glycoprotein ◽

Drug Efflux Transporters

Objective: The aim of the present study was to determine whether curcumin (CM) can prevent drug sensitivity of breast cancer (BC) cells when E andβ-E2 are administered together and whether the underlying mechanism involves modulation of drug efflux transporters.Methods: MCF7 BC cells were treated with the vehicle only, E+β-E2, or E+β-E2+CM repeatedly for 8 weeks. Afterward, the cells were harvested,counted, and isolated for total RNA extraction. Total RNA was then processed into cDNA and further processed for the determination of mRNAexpression patterns of drug efflux transporters (P-glycoprotein, BCRP, and MRP1).Results: Decreased sensitivity of BC cells was shown by the increased cell viability of MCF7 cells after 8 weeks. This condition was accompanied withincreased mRNA expression of P-glycoprotein, BCRP, and MRP1 in cells treated with E+β-E2, as compared with the vehicle only. CM, administered incombination with E+β-E2, resulted in decreased cell viability versus E and β-E2 and also decreased in mRNA expression of P-glycoprotein, BCRP, andMRP1.Conclusion: CM partially reversed the sensitivity loss of BC cells to E in the presence of β-E2 by modulating drug efflux transporters.

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