The role of serotonin and p53 status in the radiation-induced bystander effect

Abstract

Purpose: The aim of this study was to investigate the role of serotonin and protein 53 (p53) status of the cells in the radiation-induced bystander effects (RIBE).

Materials and methods: The radiation-induced bystander response was investigated in human MCF-7 breast cancer cells and human HCT116 colorectal cancer cells employing medium-transfer experiments and micronuclei (MN) induction as an end-point. Irradiated cell conditioned medium (ICCM) from cells exposed to α-particle or γ-radiation was filtered and transferred to unirradiated cells 2 h following irradiation. MCF-7 cells were irradiated with 0.5 Gy α-particles, while HCT116 p53^+/+ and HCT116 p53^−/− cells were irradiated with 0.5 Gy γ-radiation.

Results: Bystander MCF-7 cells, recipient of ICCM from 0.5 Gy α-particle irradiated MCF-7 cells grown in high serotonin conditions showed a modest but significant increase in MN, while MCF-7 cells receiving ICCM with low serotonin levels did not show any bystander effect. Added serotonin (100 ng/ml) led to a bystander effectin HCT116 p53^−/− cells recipient of ICCM from 0.5 Gy γ-irradiated HCT116 p53^+/+ cells, but had no effect when the ICCM was from γ-irradiated HCT116 P53^−/− cells.

Conclusion: The results indicate that serotonin levels in the medium play a role in the RIBE and that there may be an interaction between the role of serotonin and the p53 status of the irradiated cells.

Keywords::

• Bystander effects
• serotonin
• p53
• γ-radiation
• α-particles

Acknowledgements

We would like to thank Dr Carmel Mothersill for the input she gave on the design of this study.

Declaration of interest

The authors report no declaration of interest. The authors alone are responsible for the content and writing of the paper. This work has been financed by the Norwegian Research Council, South-Eastern Norway Regional Health Authority and the Norwegian Cancer Society. This work was part of the Non-targeted effects of ionising radiation (NOTE) (PO36465, FI6R) Euratom specific programme for research and training nuclear energy, 6th Framework Programme of European Commission.