Radiosensitizing effect of mesoporous silica-encapsulated gold nanorods on human triple-negative breast cancer cells

Objective: To investigate the radiosensitizing effect of mesoporous silica-encapsulated gold nanorods (GNRs@mSi0₂) combined with 6 MV X-ray on human triple-negative breast cancer MDA-MB-231 cells and its possible mechanism. Methods: A transmission electron microscope was used to analyze the morphology and intracellular distribution of GNRs@mSi0₂. An atomic absorption spectrophotometer was used to evaluate the uptake of GNRs@mSi0₂ by cells. The CCK-8 assay was used to measure the cytotoxicity of different concentrations of GNRs@mSi0₂. The colony formation assay was used to determine the effect of GNRs@mSi0₂ on the radiosensitivity of cells. Flow cytometry was used to measure the cell cycle, apoptosis, and the level of reactive oxygen species. Between-group comparison was made by paired t test. Results: The uptake of GNRs@mSi0₂ by MDA-MB-231 cells reached a peak value at 24 h, which was (7.09 ± 0.26)-fold higher than that in the control group and significantly higher than those in other groups (P = 0.002-0.014). After exposure to 12.5-50.0 μg/ml GNRs@mSi0₂ for 24 h, more than 90% of the cells remained alive. The D₀, D_q, and SF₂ values in the GNRs@mSi0₂ + irradiation group were lower than those in the irradiation alone group, yielding a sensitization enhancement radio of 1.27(radio of SF₂ values). The apoptosis rate was (30.4 ± 0.68)% in the GNRs@mSi0₂+irradiation group. The proportion of cells in G₂/M phase was (31.25 ± 0.75)% in the GNRs@mSi0₂+irradiation group, which was significantly higher than those in other groups (P = 0.003-0.033). Conclusions: Mesoporous silica-encapsulated gold nanorods can effectively enhance the radiosensitivity of human triple-negative breast cancer MDA-MB-231 cells to 6 MV X-ray. (authors)