Cell-specific Reduction in Viability of Two Breast Cancer Cell Lines after Exposure to Gold Nanoparticles

Aims: Nanoparticle composites are a recent research hotspot, with the potential to be drug-delivery vehicles for more efficient treatment of malignant cancerous tumors. However, as this is a relatively new field, the safety of these nanoparticles is of concern. In this study, we assess whether two preparations of gold nanoparticles, HPN1 and HGN2, affect cell viability using a metabolic assay.

Study Design: We treated two breast cancer cell lines, MCF-7 and MDA-MB-231, with two different nanoparticle preparations for five days. Following treatment, we assessed changes in cellular metabolic activity using an MTT assay.

Methodology: HPN1 are 32 nm diameter colloidal gold nanoparticles, which reflect a purple hue, while HGN2 are 10 nm diameter and reflect a yellow-orange color. We plated MDA-MB-231 or MCF-7 cells into a 6-well plate at 60% confluence. After 24 hours, we treated cells with fresh media containing 5-10% of HPN1 or HGN2 nanoparticles or PBS control. After 120 hours, we assessed the metabolic activity of live cells using a standard MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, performed in triplicate. Univariate analysis of variance (ANOVA) was performed using SPSS, with P=0.05 indicating significant variation from the controls.

Results: Interestingly, we show little change in cell activity after exposure of human MDA-MB-231 breast cancer cells to fresh and aged nanoparticles for five days; however, MCF-7 breast cancer cells responded to the two nanoparticles differently. After nanoparticles had been stored for several months, treatment with HPN1 led to a loss of viability; in contrast, HGN2 increased proliferation.

Conclusion: We must be cautious moving forward in the development of new chemotherapeutic techniques, since acute tests may not be indicative of the true toxicity of these compounds.