Characterization of UVA biophoton emission and survival of α-irradiated HCT116+/+ cells via radium exposure

Abstract

Background: It’s been hypothesized that biophoton production is a result of the generation of excited species followed by relaxation of these excited species to a stable state. This can occur as a result of many stressors including irradiation from radioactive materials. Cell exposure to radium (Ra-226) has not been thoroughly explored for biophoton production. Furthermore, biophoton production is often associated with oxidative stress and cell death which is concurrently also an area of exploration. Objectives: The objective of this study was to characterize biophoton emission and additionally observe cell survival from α-irradiated HCT116+/+ cells via radium exposure. We aim to expand evidence that supports increased biophoton production and decreased cell survival as a result of oxidative stress and exposure to radioactive material. Methods: HCT116+/+ cells were standardly cultured in this study. For characterization of biophotons, cell groups were irradiated with 10, 100, 1000 and 10,000mBq/ml of Ra-226 for 24 hours. A photon counter was used to quantify counts. For characterization of cell survival, standard clonogenic assay techniques were used. Cell groups were irradiated with the same concentrations for Ra-226 and colonies were counted 7-9 days later. Results: No significant results were seen when observing biophoton counts from Ra-226 irradiated groups compared to a background count. Furthermore, there was a significant difference between Ra-226 irradiated groups when compared to a positive control known to produce biophotons. Some significant differences were seen in the surviving fraction of directly irradiated cells when looking at the different concentrations of Ra-226. However, overall there was a correlation that could be seen where an increase in concentration of Ra-226 resulted in a decreased surviving fraction of cells. Conclusions: The hypothesis of this study was partially supported where increased exposure and sensitivity to Ra-226 showed decreased cell survival, and assumed to have implications on biophoton production at higher concentrations although was not observed here at environmentally relevant concentrations. It was also concluded that biophoton production and oxidative stress are independent events. The significance of biophoton production as a radiation-induced bystander effect was explored as an implication of this study.