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Role of mitochondrial DNA in radiation exposure
K Yoshida1, H Yamazaki, S Ozeki
1Division of Multidisciplinary Radiotherapy, Osaka University Graduate School of Medicine, Suita, Japan.
Purpose:
To evaluate the role of mitochondrial DNA (mtDNA) following exposure to ionizing irradiation.
Materials And Methods:
We examined two human osteosarcoma cell lines either lacking mtDNA (143B.rho(0)206; rho0 cells) or having normal mtDNA (143B.TK-; rho+ cells). Cell survival curves were generated by using colony formation and micronucleus assay. The delay in population doubling time after irradiation was evaluated with dye exclusion tests.
Results:
No significant difference was seen between rho+ and rho0 cell lines in colony formation assay. In micronucleus assay, rho0 cells showed a significantly lower rate of micronucleus formation. The ratios of binucleated cells with micronuclei were 0.49 for rho+ cells and 0.25 for rho0 cells (p=0.005). In the dye exclusion test, rho0 cells revealed a delay of about 1.6 times in population doubling time compared with the control after 5 Gy of irradiation, similar to the 1.7 times of rho+ cells.
Conclusion:
In the human osteosarcoma cell line 143B.TK-, mtDNA does not influence clonogenic survival and delay of population doubling time after irradiation. However, the difference in micronucleus formation shows that mtDNA influences DNA damage after radiation exposure.
Insights
Mitochondrial DNA (mtDNA) does not affect cell survival or population doubling time after irradiation in osteosarcoma cells. However, mtDNA influences DNA damage, as shown by reduced micronucleus formation in cells lacking mtDNA.
Area of Science:
- Cell Biology
- Radiation Oncology
- Genetics
Background:
- Mitochondrial DNA (mtDNA) plays a crucial role in cellular energy metabolism and is susceptible to damage.
- Ionizing radiation can induce DNA damage and affect cell survival.
- The specific role of mtDNA in the cellular response to ionizing radiation requires further elucidation.
Purpose of the Study:
- To investigate the influence of mitochondrial DNA (mtDNA) on the response of human osteosarcoma cells to ionizing irradiation.
- To determine if mtDNA affects clonogenic survival, population doubling time, and DNA damage after radiation exposure.
Main Methods:
- Comparison of two human osteosarcoma cell lines: one lacking mtDNA (rho0) and one with normal mtDNA (rho+).
- Assessment of cell survival using colony formation and micronucleus assays.
- Evaluation of population doubling time delay using dye exclusion tests after irradiation.
Main Results:
- No significant difference in clonogenic survival was observed between rho+ and rho0 cells post-irradiation.
- Cells lacking mtDNA (rho0) exhibited a significantly lower rate of micronucleus formation compared to rho+ cells.
- Both rho+ and rho0 cells showed similar delays in population doubling time after irradiation.
Conclusions:
- Mitochondrial DNA (mtDNA) does not impact clonogenic survival or the delay in population doubling time in 143B.TK- osteosarcoma cells following ionizing irradiation.
- The reduced micronucleus formation in mtDNA-deficient cells suggests that mtDNA influences the extent of DNA damage induced by radiation.