Gold nanoparticles in combination with megavoltage radiation energy increased radiosensitization and apoptosis in colon cancer HT-29 cells

Abstract

Purpose: Gold nanoparticles (GNP) act as a radiosensitizer in radiation therapy. However, recent studies have shown contradictory evidence in terms of radiosensitization in the presence of GNP combined with X-ray megavoltage energy (MV) on different cell types. In this study, the effect of GNP on radiosensitization enhancement of HT-29 human colorectal cancer cells at MV X-ray energy was evaluated.

Materials and methods: The cytotoxicity and radiosensitization of GNP were evaluated in HT-29 human colorectal cancer cells by MTS-assay and multiple MTS-assay, respectively. Cellular uptake was assayed using graphite furnace atomic absorption spectrometry (GFAAS). Apoptosis and cell cycle progression were determined by an Annexin V-FITC/propidium iodide (PI) kit and PI/RNase solution with flow cytometry, respectively.

Results: Results showed that the cell viability of the HT-29 cells was not influenced by exposure to different concentrations of GNP (10–100 μM). GNP alone did not affect the cell cycle progression and apoptosis. In contrast, GNP, in combination with radiation (9 MV), induced more apoptosis. The interaction of GNP with MV energy resulted in a significant radiosensitization enhancement compared with irradiation alone.

Conclusion: It was concluded that GNP may work as bio-inert material on HT-29 cancer cells and their enhancement of radiosensitization may be due to increase in the absorbed irradiation dose.

Keywords:

• Apoptosis
• cell cycle
• gold nanoparticles
• mega-voltage
• radiosensitizer

Acknowledgements

The authors are highly thankful to all technicians who provided support during the course of research. Authors would like to thank, Shahram Monadi, supervisor of radiation therapy section at Seyed Al-shohada hospital, Isfahan for his assistance in irradiation of the cells.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding

The part of this work was supported by Golestan University of Medical Science and Iran National Science Foundation, Iran (Grant no: 91003517).