Sensitivity of mitochondrial DNA depleted ρ0 cells to H₂O₂ depends on the plasma membrane status

To clarify the relationship between mitochondrial DNA (mtDNA)-depleted ρ0 cells and the cellular sensitivity to hydrogen peroxide (H₂O₂), we established HeLa and SAS ρ0 cell lines and investigated their survival rate in H₂O₂, radical scavenging enzymes, plasma membrane potential status, and chronological change in intracellular H₂O₂ amount under the existence of extracellular hydrogen peroxide compared with the parental cells. The results revealed that ρ0 cells had higher sensitivity to H₂O₂ 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 H₂O₂ amount significantly increased only in ρ0 cells after 50 μM H₂O₂ 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 H₂O₂. As a consequence, ρ0 cells have a higher H₂O₂ sensitivity than the parental cells.