Effects of N, N'-Di-(m-methylphenyi)-3, 6-dimethyl-1, 4-dihydro-1, 2, 4, 5-tetrazine-1, 4-dicarboamide on proliferation, apoptosis and differentiation of NB4 leukemia cells in vitro / 中国实验血液学杂志

ABSTRACT

The purpose of this study was to explore the effect of N, N'-di-(m-methylphenyi)-3, 6-dimethyl-1, 4-dihydro-1, 2, 4, 5-tetrazine-1, 4-dicarboamide (ZGDHu-1) on proliferation, differentiation and apoptosis in NB4 human leukemia cell line and its possible mechanism. Different concentrations of ZGDHu-1 and the different time of cultivation were used to treat NB4 cells. The proliferation inhibition of NB4 cells was analysed by cell counting, alive cell count, MTT assay. Cell apoptosis was determined by cell morphology, DNA agarose gel electrophoresis, DNA content, Annexin-V/PI and Hoechst 33258 labeling method. The analysis of cell morphological change, expression of CD11b, CD13 and NBT reduction were performed to evaluate the differentiation of NB4 cells. The expressions of bcl-2, bax and phosphorylated p38MAPK or STAT3 were detected by flow cytometry. While the expression of hTERT mRNA in transcriptional level was measured by fluorescence quantitative RT-PCR. The results showed that ZGDHu-1 could inhibit NB4 cell proliferation viability within a certain range of treating time and does, IC(50) values at 48 and 72 hours were 450 ng/ml and 200 ng/ml respectively. A majority of NB4 cells were arrested in G(2/M) phase and a progressive decline of cells was seen in G(0/1). The NB4 cells apoptosis was confirmed by cell typical cell morphology, DNA fragments and sub-G(1) phase peak as well as Hoechst33258 and Annexin-V/PI labeling method with a time-dose-related manner. The morphology of NB4 cells cultured in the presence of 2 - 100 ng/ml ZGDHu-1 for three days was more mature with higher NBT positivity and expressions of CD11b and CD13 than those in control. The expression of phosphor-p38MAPK and bax was increased while phosphor-STAT3 and bcl-2 were unchanged by the treatment of ZGDHu-1. ZGDHu-1 could decrease the expression of hTERT-mRNA in a dose-dependent manner. It is concluded that ZGDHu-1 can inhibit proliferation, induce differentiation and apoptosis of NB4 cells. The mechanism may be associated with up-regulation of bax expression, enhancement of phosphor-p38MAPK activation and inhibition of hTERT-mRNA.