Differential Radiosensitizing Effect of 50 nm Gold Nanoparticles in Two Cancer Cell Lines

SIMPLE SUMMARY: Nanoparticle treatment on tumor cells is proposed for its potential radiosensitizing properties, increasing the radiation effect on tumor cells and reducing the adverse effects on healthy tissues. The present study evaluates, on two cell lines derived from colon and breast adenocarcinomas, the impact of irradiation in the presence of specifically targeted gold nanoparticles. Cells were irradiated in the absence and in the presence of non-functionalized or specifically functionalized gold nanoparticles. The results pointed out that actively targeting gold nanoparticles has a clear radiosensitizing effect in both cell lines. ABSTRACT: Radiation therapy is widely used as an anti-neoplastic treatment despite the adverse effects it can cause in non-tumoral tissues. Radiosensitizing agents, which can increase the effect of radiation in tumor cells, such as gold nanoparticles (GNPs), have been described. To evaluate the radiosensitizing effect of 50 nm GNPs, we carried out a series of studies in two neoplastic cell lines, Caco2 (colon adenocarcinoma) and SKBR3 (breast adenocarcinoma), qualitatively evaluating the internalization of the particles, determining with immunofluorescence the number of γ-H2AX foci after irradiation with ionizing radiation (3 Gy) and evaluating the viability rate of both cell lines after treatment by means of an MTT assay. Nanoparticle internalization varied between cell lines, though they both showed higher internalization degrees for functionalized GNPs. The γ-H2AX foci counts for the different times analyzed showed remarkable differences between cell lines, although they were always significantly higher for functionalized GNPs in both lines. Regarding cell viability, in most cases a statistically significant decreasing tendency was observed when treated with GNPs, especially those that were functionalized. Our results led us to conclude that, while 50 nm GNPs induce a clear radiosensitizing effect, it is highly difficult to describe the magnitude of this effect as universal because of the heterogeneity found between cell lines.