Objective     To observe the effect of artesunate (Art) on the proliferation of human esophageal carcinoma cell line Eca109 and the growth of transplantation tumors of nude mice

and explore the possible involvement of CDC25A expression in the cell cycle arrest induced by Art.      Methods     MTT method was employed to detect the proliferation of the Eca109 cells and normal human peripheral blood mononuclear cells (hPBMC) after Art treatment. Cell cycle of the tumor cells was assayed by

flow cytometry. Inhibitory effects of Art on the transplanted tumor on nude mice were observed by mass weight

volume and morphological method. The expression of CDC25A in the Eca109 cells was examined by RT-PCR and Western blotting.      Results     Art significantly inhibited the proliferation of Eca109 with the IC

50

of (68.80±0.76) μmol/L

while it had weaker effect on that of the hPBMC induced by Con A. At lower doses of Art

the number of Eca109 cells during G

0

/G

1

was increased

and that at S phase was reduced dramatically. However

when the concentration was up to 100 μmol/L

most of cells were arrested at G

2

/M phase. The volume and weight of transplanted tumor receiving Art treatment were smaller and lower than those of control group

with the maximal inhibitory rate of 76.4%. Art dramatically inhibited the mRNA as well as protein expressions of CDC25A in the Eca109 cells.      Conclusion     Art can inhibit the proliferation of tumor cells and transplanted tumor without apparent side effect

possibly by the mechanism of modulating  cell cycle through CDC25A down-regulation.