Lipid peroxidation increases hydrogen peroxide permeability leading to cell death in cancer cell lines that lack mtDNA.

4-Hydroxynonenal (HNE) is an important product of plasma membrane lipid peroxidation, which is a cause of cell and tissue injury. Mitochondrial DNA (mtDNA)-depleted ρ cells were established using human cervical cancer and oral squamous cell carcinoma cell lines. We investigated the effect of reactive oxygen species in ρ cells, especially the mechanism of hydrogen peroxide (H O )-mediated cell death. These cell were subjected to high oxidative stress and, compared with their parental cells, showed greater sensitivity to H O and high lipid peroxidation. Upregulation of HNE in the plasma membrane was observed prior to the increase in intracellular H O . The amount of oxidized lipid present changed H O permeability and administration of oxidized lipid led to further cell death after treatment with H O . Expression levels of lipoxygenase ALOX genes (ie ALOX5, ALOX12, and ALOX15) were upregulated in ρ cells, as were expression levels of ALOX12 and ALOX15 proteins. ALOX5 protein was mainly distributed in the nucleus, while ALOX12 and ALOX15 proteins were distributed in the nucleus and the cytoplasm. Although expression of COX2 gene was upregulated, its protein expression did not increase. ALOX (especially ALOX15) may be involved in the sensitivity of cancer cells to treatment. These data offer promise for the development of novel anticancer agents by altering the oxidation state of the plasma membrane. Our results showed that lipid peroxidation status is important for H O sensitivity and that ALOX15 is involved in lipid peroxidation status.