Induction of apoptosis by high-dose gold nanoparticles in nasopharyngeal carcinoma cells

Abstract

Nasopharyngeal carcinoma (NPC) is a rare malignancy in most parts of the world, but is a common cancer in southern Asia. Local recurrent disease and distant metastasis of NPC are still the unsolved problems. Recently, gold nanoparticles (AuNPs) have been developed as potential in vivo diagnostic and therapeutic agents. However, their role on nasopharyngeal cancer remains unknown. The object of this study is to investigate if AuNPs can be used as a new therapeutic agent for NPC by evaluating their anti-tumor effect in vitro. The AuNPs were prepared by the reduction of chloroauric acid to neutral gold. Their size distribution and microstructures were characterized by transmission electron microscopy (TEM). To evaluate their cytotoxic effect, NPC cell line TW01 and Human Nasal Epithelial Cells (HNEpC) were cultured in various concentrations of AuNPs for 3 days. Cell viability was evaluated by Trypan Blue viability assay while morphologic findings were observed via light microscopy. Terminal deoxynucleotidyltransferase-mediated dUPT nick end labeling (TUNEL) assay was used to detect apoptosis. AuNPs prepared in this study had an average diameter of 20.5nm and they were observed under light microscopy as dark material aggregated in the cells after treatment. Contrary to the HNEpC, the AuNPs reduced cell viability of NPC cell in a concentration-dependant manner by Trypan Blue assay, especially at high concentration. Besides, cell apoptosis was demonstrated by positive TUNEL assay. The AuNP possesses specific imaging properties and is cytotoxic to NPC cells at high concentrations.