Epigallocatechin gallate-capped gold nanoparticles enhanced the tumor suppressors let-7a and miR-34a in hepatocellular carcinoma cells.

Epigallocatechin gallate (EGCG), major constituent of green tea, possesses antioxidant, antiviral, and anticancer activities. Gold nanoparticles (AuNPs) play an important role in drug delivery due to their stability, ease of surface functionalization, and unique optical properties. This study aimed to investigate the influence of EGCG-capped AuNPs on tumor suppressor miRNAs (miR-34a and let-7a) and their targeted cell death mediators in HepG2 cells, compared with celastrol. EGCG-AuNPs were prepared and characterized. antioxidant activity was estimated by DPPH scavenging assay; cytotoxicity was assessed by MTT assay; let-7a and miR-34a expression was analyzed by qPCR; and miRNAs targets (c-Myc and caspase-3) were assessed by ELISA and immunocytofluorescence, respectively. The average size of EGCG-AuNPs was 35 nm, with a λmax of ~535 nm. EGCG-AuNPs exerted cytotoxicity on HepG2 cells stronger than that of EGCG alone. EGCG-AuNPs and EGCG presented half-maximal radical scavenging concentrations (SC50) of 539 µg/ml and 45 µg/ml, respectively. The expression levels of let-7a and miR-34a were significantly elevated in HepG2 cells after EGCG-AuNP treatment for 72 h. c-Myc protein expression was reduced, whereas caspase-3 expression was increased following treatment with EGCG-AuNPs. In conclusion, Au-NPs are effective carrier for EGCG, and EGCG-AuNPs are promising anti-cancer agent.