Abstract: Objective To study the radiobiological characteristics of a HepG2 cell line with mitochondrial DNA (mtDNA)
deletion. Methods HepG2 cells were cultured in a medium containing ethidium bromide, acetylformic acid and uracil. The
HepG2 cell line with mtDNA deletion (ρ0HepG2 cells) were acquired after 30 subcultures by limited dilution cloning. The cell
survival was then observed in the absence of acetylformic acid and uracil, and the total mtDNA deletion in the cells was
confirmed by PCR. The radiosensitivity of HepG2 and ρ0HepG2 cells was evaluated by exposure to gradient doses of 6 MV
X ray irradiation. The cell apoptosis was assessed following a 2 Gy X-ray exposure with Hochest33342 staining, and the
invasiveness of ρ0HepG2 cells was measured by Transwell assay. Results HepG2 cells could survive 30 subcultures in the
presence of ethidium bromide, and massive cell death occurred after removal of acetylformic acid and uracil from the medium.
PCR confirmed total mtDNA deletion from ρ0HepG2 cells, whose α/β value was significantly lower than that of HepG2 cells.
ρ0Hep-G2 cells showed an obviously lowered cell apoptosis rate following X-ray exposure with enhanced cell invasiveness.
Conclusion HepG2 cells can be induced by ethidium bromide into ρ0HepG2 cells with an increased radiation resistance,
anti-apoptosis ability and cell invasiveness.