Dark Sweet Cherry (Prunus avium L.) Juice Phenolics Rich in Anthocyanins Exhibit Potential to Inhibit Drug Resistance Mechanisms in 4T1 Breast Cancer Cells via the Drug Metabolism Pathway.

Anthocyanins (ACNs) from dark sweet cherries (DSCs) have shown efficacy against breast cancer (BC) cells, particularly triple-negative breast cancer (TNBC) cells, without affecting normal breast cells. This study investigated the impact of ACNs on TNBC cells, focusing on drug resistance mechanisms involving drug metabolism and transport enzymes. Specifically, it was examined whether ACNs influenced Doxorubicin (DOX) metabolism by targeting drug metabolism enzymes (phase I metabolism) and drug transport enzymes (phase III metabolism) in TNBC cells. 4T1 TNBC cells were treated with ACNs, DOX, and the combination of both (ACN-DOX). Results showed a synergistic inhibition of cell viability by ACNs and DOX. In addition, the modulation of phase I drug-metabolizing enzymes was exerted by ACNs, reducing the activity of cytochrome P450 (CYP) enzymes induced by DOX. A reduction of drug efflux by ACNs was shown by decreasing P-glycoprotein (P-gp) activity, leading to a higher intracellular accumulation of DOX. These effects were confirmed using CYP and P-gp inducers and inhibitors, showing their impact on cell viability. In conclusion, the combination of ACNs with DOX has the potential to lower DOX doses, enhance its efficacy, and possibly reduce side effects, offering a promising approach for TNBC treatment.