Chemosensitization of cancer cells via gold nanoparticle-induced cell cycle regulation.

We have previously shown that plasmonic nanoparticles conjugated with nuclear-targeting and cytoplasm-targeting peptides (NLS and RGD, respectively) are capable of altering the cell cycle of human oral squamous carcinoma cells (HSC-3). In the present work, we show that this regulation of the cell cycle can be exploited to enhance the efficacy of a common chemotherapeutic agent, 5-Fluorouracil, by pretreating cells with gold nanoparticles. Utilizing flow cytometry cell cycle analysis, we were able to quantify the 5-Fluorouracil efficacy as an accumulation of cells in the S phase with a depletion of cells in the G2/M phase. Two gold nanoparticle sizes were tested in this work; 30 nm with a surface plasmon resonance at 530 nm and 15 nm with a surface plasmon resonance at 520 nm. The 30 nm nuclear-targeted gold nanoparticles (NLS-AuNPs) showed the greatest 5-Fluorouracil efficacy enhancement when 5-Fluorouracil treatment (500 μm, 48 h) is preceded by a 24-h treatment with nanoparticles. In conclusion, we show that nuclear-targeted 30 nm gold nanoparticles enhance 5-Fluorouracil drug efficacy in HSC-3 cells via regulation of the cell cycle, a chemosensitization technique that could potentially be expanded to different cell lines and different chemotherapies.