OBJECTIVETo study whether N, N'-di-(m-methylphenyi)-3,6-dimethyl-1,4-dihydro-1,2,4,5-tetrazine-1,4-dicarboamide (ZGDHu-1) inhibits proliferation and induces apoptosis in human lung carcinoma cell line EBC-1 cells and its molecular mechanism.

METHODSDifferent concentrations of ZGDHu-1 and different times of culture were used to treat EBC-1 cells in vitro. The inhibition of proliferation was measured by BrdU-ELISA. Cell apoptosis was detected by Annexin V/PI staining and cellular DNA fragmentation ELISA. Phosphorylated p38MAPK and STAT3 were examined by flow cytometry. The protein expressions of bcl-2, bax, p53, Fas, and caspase-3 were detected by Western blot analysis.

RESULTSZGDHu-1 inhibited EBC-1 cell proliferation within a certain range of treating times and does, with a 24 h IC(50) of (295 ± 25) ng/ml, 48 h of (112 ± 8) ng/ml and 72 h of (23 ± 2) ng/ml. The EBC-1 cell apoptosis was confirmed by Annexin V/PI labeling and cellular DNA fragmentation ELISA in a dose-related manner. When EBC-1 cells were treated with 50, 200, and 500 ng/ml ZGDHu-1 for 48 h, the expression rates of phosphor-p38MAPK protein were 67.4%, 88.2%, 91.1%, respectively, and that of the control was 10.6%. That of STAT3 protein were 56.5%, 43.6% and 34.6%, respectively, and that of the control was 89.1%. The expression of bax, p53 and Fas protein was significantly increased, that of bcl-2 was not changed, and that of caspase-3 was significantly decreased by the ZGDHu-1 treatment.

CONCLUSIONZGDHu-1 can inhibit proliferation and induce apoptosis in EBC-1 cells. The mitochondrial pathway mediated by Fas may be one of its mechanisms. The apoptosis of EBC-1 cells may associate with up-regulation of phosphor-p38MAPK and down-regulation of phosphor-STAT3 in the cells.