Differential response of MCF7, MDA-MB-231, and MCF 10A cells to hyperthermia, silver nanoparticles and silver nanoparticle-induced photothermal therapy

Purpose: Silver nanoparticles (Ag NP) can generate heat upon exposure to infrared light. The in vitro response of breast cell lines to Ag NP, both with and without nanoparticle-induced heating was evaluated. Materials and methods: Ag NP heat generation, intracellular silver concentration, and cell viability of MDA-MB-231, MCF7, and MCF 10A breast cells with Ag NP alone, or after exposure to 0.79 or 2.94 W/cm(2) of 800 nm light were evaluated. Results: The concentration of Ag NP to induce sufficient heat for cell death, upon exposure to 800 nm light, was 5-250 mu g/mL. Clonogenics assay indicates a cytotoxic response of MCF7 (45% decrease) and MDA-MB-231 (80% decrease) cells to 10 mu g/mL, whereas MCF 10A had a 25% increase. Without Ag NP, MDA-MB-231 cells were more susceptible to hyperthermia, compared to MCF7 and MCF 10A cells. Clonogenics assay of Ag NP-induced photothermal ablation demonstrated that MCF 10A cells have the highest survival fraction. MCF7 cells had more silver in the cytoplasm, MDA-MB-231 cells had more in the nuclei, and MCF 10A cells had equivalent concentrations in the cytoplasm and nuclei. Conclusions: Ag NP are effective photothermal agents. A secondary benefit is the differential response of breast cancer cells to Ag NP-induced hyperthermia, due to increased intracellular silver content, compared to non-tumorigenic breast epithelial cells.