Influence of chronic low-dose/dose-rate high-LET irradiation from radium-226 in a human colorectal carcinoma cell line

Nguyen T K Vo; Bibi S H Sokeechand; Colin B Seymour; Carmel E Mothersill

doi:10.1016/j.envres.2017.04.041

Influence of chronic low-dose/dose-rate high-LET irradiation from radium-226 in a human colorectal carcinoma cell line

Environ Res. 2017 Jul:156:697-704. doi: 10.1016/j.envres.2017.04.041. Epub 2017 May 5.

Authors

Nguyen T K Vo¹, Bibi S H Sokeechand², Colin B Seymour³, Carmel E Mothersill³

Affiliations

¹ Radiation Sciences Program, School of Graduate and Postdoctoral Studies, McMaster University, Hamilton, ON, Canada. Electronic address: von1@mcmaster.ca.
² Radiation Sciences Program, School of Graduate and Postdoctoral Studies, McMaster University, Hamilton, ON, Canada.
³ Department of Biology, McMaster University, Hamilton, ON, Canada.

PMID: 28477580
DOI: 10.1016/j.envres.2017.04.041

Abstract

Purpose: To evaluate potential damages of chronic environmentally relevant low-dose/dose-rate high-LET irradiation from a naturally occurring alpha-emitting radionuclide (radium-226, ²²⁶Ra) on a human colorectal carcinoma HCT116 p53^+/+ cell line.

Methods: Clonogenic survival assays and mitochondrial membrane potential (MMP) measurement with a sensitive fluorescent MMP probe JC-1 were performed in HCT116 p53^+/+ cells chronically exposure to low doses/dose rates of ²²⁶Ra with high-LET. Comparisons were made with the human non-transformed keratinocyte HaCaT cell line and acute low-dose direct low-LET gamma radiation.

Results and conclusion: The chronic low-dose/dose-rate alpha radiation (CLD/DRAR) did not reduce the clonogenic survival of HCT116 p53^+/+ cells over the period of 70 days of exposure. Only one significant reduction in the HCT116 p53^+/+ cells' clonogenic survival was when cells were grown with 10,000mBq/mL ²²⁶Ra for 40 days and progeny cells were clonogenically assessed in the presence of 10,000mBq/mL ²²⁶Ra. The cumulative doses that cells received during this period ranged from 0.05 to 46.2mGy. The mitochondrial membrane potential (MMP) dropped initially in both HCT116 p53^+/+ and HaCaT cells in response to CLD/DRAR. The MMP in HCT116 p53^+/+ cells recovered more quickly at all dose points than and that in HaCaT cells until the end of the exposure period. The highest dose rate of 0.66mGy/day depolarized the HaCaT's mitochondria more consistently during the exposure period. The faster recovery status of the MMP in HCT116 p53^+/+ cells than that in HaCaT cells was also observed after exposure to acute low-dose gamma rays. Overall, it was found that CLD/DRAR had little impact on the MMP of human colorectal cancer and keratinocyte cell lines.

Keywords: Chronic low-dose alpha radiation; Clonogenic survival; Colorectal carcinoma; Mitochondrial membrane potential; Radium.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cell Line
Cell Survival / radiation effects
Colorectal Neoplasms
Gamma Rays / adverse effects
HCT116 Cells
Humans
Keratinocytes / radiation effects
Membrane Potential, Mitochondrial / radiation effects
Radium / toxicity*

Substances

Radium