Studies On The Anti-leukemia Effect Of The Extract From Lysimachia Clethroides Duby And Its Mechanism

AIM: To study the anti-leukemia effect of the extract from Lysimachia clethroides Duby and its primary mechanism.METHODS: Using the active tracking method to find the effective composition of LCD. Then we investigated the inhibitory effects of ZE4 on the transplantable tumor models of S1210. After treatment with ZE4, the growth inhibition of K562 cells was assessed by MTT colorimetric assay and 3H-TdR assay.The effect on cell cycle in K562 cells was observed by flow cytometry. Cytotoxic effect was analysed by single cell electrophoresis assay. Nuclear morphological changes were observed by Hoechst33258 fluorescent staining. Flow cytometry and Western blot analysis were used to study the apoptotic mechanisms involved in death of K562 cells.RESULTS: ZE4 had a significant anti-leukemia effect in vivo. The proliferation of K562 cells was significantly inhibited in a dose- and time-dependent manner after ZE4 treatment. And Cell cycle analysis indicated that treatment with ZE4 decreased the proportion of cells in S phase and increased the proportion of cells in G0/G1 and/or G2/M phases of the cell cycle. In addition, apoptosis was identified by sub G0 population. Single cell electrophoresis assay indicated ZE4-treated cells presented clear leaked DNA tails. After treatment with ZE4, nucleus shrunk and the chromosomes were condensed and decomposed into fragments, which showed intensive fluorescence. We also made it clear that ZE4 could downregulate Bcl-2 expression, upregulate the protein expression of fas,Trail and DR5.CONCLUSION: ZE4 had a significant anti-leukemia effect in vivo. The regulation of a series of apoptosis related proteins such as fas,DR5 and Trail by ZE4 suggested its ability of inducing apoptosis is one mechanism of its effects, which may involve DNA injury simultaneously.