Sterigmatocystin induced apoptosis in human pulmonary cells in vitro

Sterigmatocystin (ST) is generally recognized as a potential carcinogen, mutagen and teratogen. Studies showed that ST could induce adenocarcinoma of lung in mice in vivo and DNA damage, cell cycle arrest in a human immortalized bronchial epithelial cell line (BEAS–2 B cells) and a human lung cancer cell line (A549 cells) in vitro. Besides, ST could induce G₂ arrest (cell cycle arrest in G₂ phase) in several other cells. Cell cycle arrest may be one of the common toxic effects of ST. As cells may undergo apoptosis or death due to cell cycle arrest, we wondered whether apoptosis is another common effect of ST in different cells in vitro. In the present study, we studied the effects of ST on proliferation and apoptosis in A549 cells and BEAS–2 B cells with 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometric analysis (FCM). The MTT results showed that proliferation inhibition following ST treatment for 24 h was observed in both A549 and BEAS–2 B cells in vitro. And increased apoptosis by FCM was also found after ST treatment. Down-regulation of Bcl-2, up-regulation of Bax and the activation of caspase-3 after ST treatment were detected by western blotting analyses. The results in the present study are consistent with our previous results, which indicated that inducing apoptosis may be a common effect of ST in different cells in vitro.