Mitochondrial DNA influences radiation sensitivity and induction of apoptosis in human fibroblasts

Background: We aimed to assess the role of mitochondrial DNA (mtDNA) in ion izing irradiation. Material and methods: We examined three human fibroblast cell lines either lacking mtDNA (rho(0) cell), carrying mutant mtDNA (syn cell) or normal mtDNA (rho(+) cell). Cell survival curves were generated wi th colony formation and dye exclusion tests. Cell cycle analysis and apopto sis assay were performed by Slow cytometry. Results: The rho(0) cell line s howed a stronger resistance to irradiation than the other two cell lines wh en assessed by the colony formation assay. In the dye exclusion test, the r ho(0) cells revealed a superior cell viability among the cell lines after 5 and 8 Gy irradiation. The rho(0) cells underwent apoptosis at lower rates than the other two cell lines after 2, 5 and 8 Gy irradiation, and showed n o alterations in the cell cycle distribution among them. Conclusion: mtDNA plays an important role in irradiation sensitivity and the induction of apo ptosis.