Troglitazone induces apoptosis in gastric cancer cells through the NAG-1 pathway.

The non-steroidal anti-inflammatory drug-activated gene (NAG-1) is a newly identified member of the transforming growth factor (TGF)-β superfamily and plays significant roles in regulating proliferation and pro-apoptotic activities. In the present study, we studied the regulation of NAG-1 by troglitazone in the cultured gastric cancer cell line BGC-823. MTT and TUNEL assays demonstrated that troglitazone potentially inhibits the proliferation of the gastric cancer cell line and induces apoptosis in vitro in a dose- and time-dependent manner. Troglitazone induced concentration-dependent NAG-1 expression in the BGC-823 cells, as assessed using immunocytochemistry. Furthermore, troglitazone increased Egr-1 protein levels in a concentration-dependent manner. In conclusion, the present study suggests that troglitazone markedly impedes proliferation and pro-apoptotic activities in BGC-823 cells, and the mechanism may partly be through the Egr-1 pathway.