Study on the anti-tumor mechanisms of the methanol extract of Stellera chamaejasme L

Objective To study the anti-tumor mechanisms of the methanol extract of Stellera chamaejasme L .(meSCL). Methods Using different doses of meSCL, the effects of them on the S180-bearing mice and tumor growth were observed in vivo , on the transformation and NK activity of S180-bearing mouse splenocytes in vivo , the growth, transformation and NK activity of normal mouse splenocytes and the growth of three kinds of tumor lines were assayed in vitro by MTT method, on the cytocycle, apoptosis and gene expressions of p53, bcl-2 and c-myc of K562 were investigated by FACS and transmission electron microscopy and on the effect growth curve of K562 was checked by the trypan blue staining-rejecting method. Results Per day 5μg/kg meSCL could inhibit the tumor growth and improve the immune function of S180-bearing mice. In vitro , 0.1～10μg/ml meSCL could stimulate normal murine splenocytes to proliferate and to transform in coordination with the optimal and suboptimal doses of ConA and enhance splenocyte NK activity. meSCL had proliferation-inhibitory effect on K562, S180 and YAC-1 in vitro and K562 cells were the most sensitive ones. The cells of apoptosis and at G_0/G_1 phase of K562 incubating with meSCL were remarkably increased, the p53 gene expression was substantially increased and the gene expressions of bcl-2 and c-myc were significantly decreased. In the period of culturing K562 cells with 0.5μg/ml meSCL for nine days, the tumor cells were all alive but the cell density did not increase. Conclusion A certain dose of meSCL can inhibit the tumor growth and improve the immune function of tumor-bearing mice. The anti-tumor mechanisms of meSCL could be explained by stimulation of the proliferation of splenocyte alone or in coordination with ConA and increase the activity of NK cells and it can hinder the cell cycle of tumor cells, inhibit their fission and proliferation, and promote their apoptosis.