In vitro cultured Spodoptera frugiperda insect cells: Model for oxidative stress-induced apoptosis

Cellular imbalance in the levels of antioxidants and reactive oxygen specie s (ROS) is directly associated with a number of pathological states and res ults in programmed cell death or apoptosis. We demonstrate the use of in vi tro cultured Spodoptera frugiperda (Sf9) insect cells as a model to study o xidative stress induced programmed cell death. Apoptosis of in vitro cultur ed Sf9 cells was induced by the exogenous treatment of H2O2 to cells growin g in culture. The AD(50) (concentration of H2O2 inducing about 50% apoptoti c response) varied with the duration of treatment, batch to batch variation of H2O2 and the physiological state of cells. At 24 h post-treatment with H2O2, AD(50) was about 475 mu m. Apoptosis could also be induced by in situ generation of H2O2 by the inhibition of catalase activity upon hydroxylami ne treatment. Hydroxylamine acted synergistically with H2O2 with an AD(50) of 2.2 mM. DMSO, a free radical scavenger, inhibited H2O2-induced apoptosis thereby confirming the involvement of reactive oxygen species. Exposure of cells to UV radiation (312 nm) resulted in a dose-dependent induction of a poptosis. These results provide evidence on the novel use of insect cells a s a model for oxidative stress-induced apoptosis.