Multifunctional Molecular Beacons-Modified Gold Nanoparticle as a Nanocarrier for Synergistic Inhibition and in Situ Imaging of Drug-Resistant-Related mRNAs in Living Cells.

Abstract

Overexpression of adenosine 5'-triphosphate-binding cassette transporters is one of the primary causes of drug resistance in cancer. Downregulating the expression of these transporters by inhibiting the mRNA translation process is an effective approach to cope up with this situation. Herein, multifunctional molecular beacons (MBs)-modified gold nanoparticle (AuNP) as a nanocarrier (MBs-AuNP) is developed for synergistic inhibition and in situ imaging of drug-resistant-related mRNAs in living cells. MBs-AuNP is composed of (i) triple specially designed molecular beacons modified on the surface of AuNP, for binding drug-resistant-related mRNAs, loading doxorubicin (Dox), and reporting the fluorescence signal, and (ii) AuNP, for loading MBs, introducing them into cells, and quenching their fluorescence. After uptake by cells, MBs-AuNP will hybridize with three different drug-resistant-related mRNAs (MDR1 mRNA, MRP1 mRNA, and BCRP mRNA), respectively, which could inhibit their translation to decrease efflux protein expression and lead to AuNP-quenched fluorescence recovery for in situ imaging. Real-time quantitative-polymerase chain reaction and western blot results showed that drug-resistant-related mRNAs and efflux proteins expression both decreased. Dox-loaded MBs-AuNP exhibited higher suppression efficacy compared to that of free Dox against HepG2/ADR (0.35 vs 1.06 μM of IC50) and MCF-7/ADR (2.78 vs >5 μM of IC50). Direct observation of intracellular hybridization events and differentiation of drug-resistant cancer cells or non-drug-resistant cancer cells could be accomplished through fluorescence imaging analysis. This nanocarrier is capable of downregulating the expression of multiple efflux proteins by gene silencing, allows in situ monitoring of silencing events, and thus provides a powerful strategy to cope up with drug resistance at the gene level.