In vitro cytotoxic and apoptotic effects of chitosan-coated gold nanoparticles on HT-29 human colorectal adenocarcinoma cells

BACKGROUND: Colorectal cancer is a major cause of cancer-related mortality worldwide. Nanotechnology has introduced nanoparticles as a promising therapeutic approach in cancer treatment. Gold nanoparticles (AuNPs) can influence critical cellular processes in cancer cells. This study evaluates the effects of chitosan-coated gold nanoparticles (CH-AuNPs) on cell viability, mitochondrial membrane potential, reactive oxygen species (ROS) production, and apoptosis-related gene expression in the human colorectal adenocarcinoma HT-29 cell line. METHODS: CH-AuNPs were synthesized and characterized using dynamic light scattering (DLS), UV-Vis spectroscopy, and atomic force microscopy (AFM). Cell viability was assessed using the MTT assay. Apoptosis, mitochondrial membrane potential (Δψm), and ROS production were analyzed via flow cytometry using Annexin V-FITC/PI, Rhodamine 123, and DCFH-DA, respectively. A clonogenic assay was used to measure colony-forming ability, and real-time qPCR was performed for gene expression analysis. RESULTS: The nanoparticles had an average size of 12.3 nm. The IC50 was 33 µM (approximately 6.5 µg/mL). They significantly reduced colony formation, decreased mitochondrial membrane potential, and induced apoptosis in HT-29 cells. ROS levels remained unchanged. BAX, Caspase-3, and CYT C gene expression increased, while anti-apoptotic BCL2 expression decreased. CONCLUSIONS: Chitosan-coated gold nanoparticles exhibit cytotoxic and apoptotic effects on HT-29 cells under in vitro conditions. These preliminary findings suggest the need for further investigation, including validation in additional colorectal cancer cell lines, assessment of selectivity, and in vivo studies, before any therapeutic application can be considered.