Apoptosis in Respiratory Epithelial Cells: Triggering by Paraquat and Modulation by L-ascorbic acid

Park, Jong Kuk; Kim, Gab Teug; Song, Hwa Sik; Park, Sang Mun

Abstract

PURPOSE
Apoptosis is a programmed cell death that is a selective process of physiological cell deletion. This study was undertaken to evaluate a paraquat-triggered apoptosis and the ability of ascorbic acid to modulate the process in the A549 cell line, a well-characterized cellular model of human lung alveolar cells.
METHODS
A 549 cells were incubated with different concentrations of paraquat for up to 24 hour, followed by 24, 48, and 72 hours of recovery in paraquat-free medium. To test the abilities of antioxidants as modulators of paraquatinduced apoptosis, we pre-treated the cells for 4 hours with 250 micrometer L-ascorbic acid (vitamin C) before exposure to paraquat, and we incubated cells with paraquat in the presence of 250 micrometer L-ascorbic acid. Apoptosis was assayed by staining the cells with FITC-annexin V, and the cells were analyzed by using flow cytometry.
RESULTS
Paraquat was inducer of apoptosis. A549 cells incubated with paraquat for up to 24 hour showed no apoptotic features, but the following incubation in a paraquat-free medium resulted in a time-dependent appearance of apoptosis. The ascorbic acid proved effective in reducing paraquat-induced apoptosis.
CONCLUSION
We propose an experimental model for investigating the steps and mechanism of paraquat-induced apoptosis in alveolar cells