Glutathione-mediated release of functional miR-122 from gold nanoparticles for targeted induction of apoptosis in cancer treatment.

Abstract

MiRs was efficiently bound to water-soluble positively charged gold nanoparticles through complementary electrostatic interaction. MiR-122 has been considered to be specifically expressed in liver and involved in inducing hepatocyte apoptosis through bcl-w pathway, which could be efficiently bound to water dispersible positively charged gold nanoparticles and conjugated with folic acid (FA) to target specific cancer cells, through complementary electrostatic interaction. These gold nanoparticles-miR-122-FA nanocomplexes (GMN) were disrupted and miR-122 was released by glutathione (GSH) at intracellular concentrations. In contrast, there was almost no detectable miR-122 released from GMN by extracellular concentration of GSH. The formation of GMN and GSH-mediated miR-122 release from the complexes were corroborated by dye displacement assay, electrophoresis experiment and transmission electron microscopy (TEM). With FA funcition, the GMN can target to the HepG2 cell membrane efficiently revealed by scanning electron microscopy (SEM). The released miR-122 retained apoptosis-inducing activity after being transfected into HepG2 cells. The transfection efficiency measured by MTT assay and flow cytometry was comparable with the positive control. We determined the effects of GMN on HepG2 cells viability and apoptosis by using fluorescence light microscopy and SDS-PAGE/immunoblots. The obvious concentration gradient of GSH in nature between the intra- and extracellular environments as well as the GSH concentration-dependent release suggest that these positively charged gold nanoparticles can be used as a novel visible vehicle for gene delivery and open up promising opportunities for target applications in the future.