Carbon ion beam is more effective to induce cell death in sphere-type A172 human glioblastoma cells compared with X-rays

Abstract

Purpose: To obtain human glioblastoma cells A172 expressing stem cell-related protein and comparison of radiosensitivity in these cells with X-rays and carbon beam.

Methods: Human monolayer-type A172 glioblastoma cells were maintained in normal medium with 10% bovine serum. In order to obtain sphere-type A172 cells the medium was replaced with serum-free medium supplemented with growth factors. Both types of A172 cells were irradiated with either X-rays or carbon ion beams and their radiosensitivity was evaluated.

Results: Serum-free medium induced expression of stem cell-related proteins in A172 cells along with the neurosphere-like appearance. These sphere-type cells were found resistant to both X-rays and carbon ion beams. Phosphorylation of histone H2A family member X persisted for a longer period in the cells exposed to carbon ion beams than in those exposed to X-rays and it disappeared quicker in the sphere type than in the monolayer type. Relative radioresistance of the sphere type cells was smaller for carbon ion beams than for X-rays.

Conclusions: We demonstrated that glioblastoma A172 cells with induced stem cell-related proteins turned resistant to irradiation. Accelerated heavy ion particles may have advantage over X-rays in overcoming the tumor resistance due to cell stemness.

Keywords::

• Glioblastoma cells
• radiosensitivity
• stem cells

Acknowledgements

We would like to thank Y-Q. Fang and M. Akaishizawa for their technical assistance. This is part of the research project with heavy ions at NIRS-HIMAC.

Declaration of interest

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

The work was supported by a research grant from the Ministry of Education, Culture, Sports, Science and Technology: Grants-in-Aid for Young Scientists (B) 21791235 (Dr Momoko Takahashi).