Prevention of geranylgeranoic acid‐induced apoptosis by phospholipid hydroperoxide glutathione peroxidase gene

Micromolar concentrations (0.5 ∼ 5 µM) of all‐ trans geranylgeranoic acid (GGA) induced cell death in a guinea pig cell line, 104C1, whereas under the same conditions GGA was unable to kill 104C1/O4C, a clone established from 104C1 cells by transfection of them with the human phospholipid hydroperoxide glutathione peroxidase ( PHGPx ) gene. GGA (5 µM) induced a loss of the mitochondrial inner membrane potential (ΔΨm) in 104C1 cells in 2 h, and their apoptotic cell death became evident in 6 h. On the other hand, 104C1/O4C cells were resistant to loss of ΔΨm and showed intact morphology until at least 24 h after addition of 10 µM GGA. Dihydroethidine, superoxide‐sensitive probe, was immediately oxidized 15 min after addition of GGA in both 104C1 and 104C1/O4C cells. The peroxide‐sensitive probe 2′,7′‐dichlorofluorescin diacetate (H 2 ‐DCF‐DA) was strongly oxidized in 104C1 cells 4 h after the addition of 2.5 µM GGA, but not in 104C1/O4C cells even in the presence of 10 µM GGA. The present results suggest that GGA induced a hyper‐production of superoxide and subsequently peroxides, which in turn may have led to dissipation of the ΔΨm and final apoptotic cell death in 104C1 cells. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.