Synthesis of novel gold nanoparticles and its radiosensitizing effect on HepG2 cells

Objective: To synthesize novel gold nanoparticles of GAL-PEG-GNPs, study its radiation effect on hepatocellular carcinoma cells HepG2 cells in vitro, and investigate the underlying mechanisms. Methods: GAL-PEG-GNPs were synthesized and characterized successfully. HepG2 cells were divided into three groups of control, GNPs and GAL-PEG-GNPs. The cytotoxicities of these compounds were tested by the CCK-8 assay and their IC₅₀ values of HepG2 cells were calculated. Cell uptake of nanoparticles was detected by TEM and ICP-MS. The radiosensitization effect of nanoparticles was tested by the colony formation assay. Cell cycle distribution was detected by FCM. The expressions of CAT, SOD, and total GSH were detected with a microplate reader, and the expressions of apoptosis-related proteins were tested by Western blot. Results: The GNPs and GAL-PEG-GNPs had absorption peaks at 520 and 530 nm, respectively, and their diameters were (22.6 ± 2.12) and (32.0 ± 1.41) nm detected by ICP-MS. The GAL-PEG-GNPs and GNPs had similar cytotoxicity profiles (P > 0.05), while GAL-PEG-GNPs could be more effectively uptaken by HepG2 cells than GNPs. The sensitive enhancement ratio (SER) of GNPs and GAL-PEG-GNPs to HepG2 cells were 1.46 and 1.95, respectively. The percentage of cells at phase of G₂/M in HepG2 population treated with GNP was higher than that of untreated cells (t = 14.20, P < 0.05). The protein expressions of Cytochrome C, Bax, Caspase-3, and Caspase-9 were up-regulated while Bcl-2 expression was down-regulated in the cells treated with GNPs/radiation or GAL-PEG-GNPs/radiation. The expressions of CAT, SOD and total GSH in the GNP treated groups were significantly decreased compared with the control group(t = 12.34, 29.39, 12.85, P < 0.05). Conclusions: GAL-PEG-GNPs has obvious radiosensitization effect on HepG2 cells, which is related to the induction of cell apoptosis and the generation of free radicals. (authors)