Sensitivity of mitochondrial DNA depleted ρ0 cells to HO depends on the plasma membrane status.

To clarify the relationship between mitochondrial DNA (mtDNA)-depleted ρ0 cells and the cellular sensitivity to hydrogen peroxide (HO), we established HeLa and SAS ρ0 cell lines and investigated their survival rate in HO, radical scavenging enzymes, plasma membrane potential status, and chronological change in intracellular HO amount under the existence of extracellular hydrogen peroxide compared with the parental cells. The results revealed that ρ0 cells had higher sensitivity to HO than their parental cells, even though the catalase activity of ρ0 cells was up-regulated, and the membrane potential of the ρ0 cells was lower than their parental cells. Furthermore, the internal HO amount significantly increased only in ρ0 cells after 50 μM HO treatment for 1 h. These results suggest that plasma membrane status of ρ0 cells may cause degradation, and the change could lead to enhanced membrane permeability to HO. As a consequence, ρ0 cells have a higher HO sensitivity than the parental cells.