Reversing Multidrug Resistance by Multiplexed Gene Silencing for Enhanced Breast Cancer Chemotherapy.

Multidrug resistance (MDR), as one of the main problems in clinical breast cancer chemotherapy, is closely related with the over expression of drug efflux transporter P-glycoprotein (P-gp). In this study, a novel drug-loaded nanosystem was developed for inhibiting the P-gp expression and reversing MDR by multiplexed gene silencing, which composes of graphene oxide (GO) modified with two molecular beacons (MBs) and Doxorubicin (Dox). When the nanosystem was uptaken by the MDR breast cancer cells, Dox was released in the acidic endosomes and MBs were hybridized with target sequences. The intracellular multidrug resistance 1 (MDR1) mRNA and upstream erythroblastosis virus E26 oncogene homolog 1 (ETS1) mRNA can be silenced by MBs, which can effectively inhibit the expression of P-gp and further prevent the efflux of Dox and reverse MDR. In vitro and in vivo studies indicated that the strategy of reversing MDR by multiplexed gene silencing could obviously increase MCF-7/Adr cells' Dox accumulation and enormously enhance the therapeutic efficacy of MDR breast cancer chemotherapy.