Objective To observe the radiosensitizing effect of gold nanoparticles（AuNPs） on SPC-A1 lung cancer cell line of megavoltage ray radiation therapy and probe its radiosesitizing mechanisms in vitro.
Methods SPC-A1 cells were cultured in vitro. The cytotoxicity effect of different concentrations of AuNPs（0， 1， 0.5， 0.25， 0.125，0.0625 mmol／L） on SPC-A1 cells were measured by CCK-8 at 24， 48 and 72 h after treatment. The experimental concentration of AuNPs was determined according to CCK-8 method. SPC-A1 cells were processed with different doses of 6MV X-ray and 4MeV electron beam including 0， 1， 2， 4， 6， 8 Gy alone or together with AuNPs（0.25 mmol／L））. The cell survival faction（SF） was evaluated by using a standard colonyforming assay. Cell cycle distribution and apoptosis of different groups were detected at 24 h after treatment with AuNPs（0.25 mmol/L） by flow cytometry assay. Results Cell viability test showed the proliferation of SPC-A1 cells was not significantly inhibited after treatment with different concentrations of AuNPs at different points of time， and had no effect on the time and concentration. The initial concentration of AuNPs（0.25 mmol／L）） was used as the concentration of the experiment. The enhanced radiosensitivity of SPC-A1 lung cancer cells has been observed. The sensitivity enhancement ratio（SER） at 37％ survival level were 1.111 and 1.214 at 24 h after treatment of AuNPs combined with 6MV Xray and 4MeV electron beam repectively. Flow cytometry showed that cell apoptosis was not increased by individual AuNPs， but the rays on cell apoptosis was significantly increased. The cell cycle detection showed that the cell cycle was accelerated at the G0／G1 phase， and arrested at the G2／M phase after the treatment with AuNPs. Conclusion AuNPs can be used for the enhancement of radiation effects on SPC-A1 lung cancer cells of megavoltage X-ray radiation therapy and electron radiation therapy beams. Its mechanism may relate to increase apoptosis and cell cycle synchronization.