Abstract: Purpose : Arsenic t rioxide (As2O3) has proved to be effective in the t reatment of some leukemias and caused apoptosis in leukinua cells and some solid tumor cells. This study focused on the effect s of low dosage of As2O3 on the esophageal carcinoma cells ( SHEEC1) . Methods : Esophageal carcinoma cells were cultured in flasks and t reated with As2O3 in concent ration of 0. 1μmol/ L , 0. 5μmol/ L and 5. 0μmol/ L , respectively. Results : The high dose (5μmol/ L) of As2O3 induced apoptosis and inhibited proliferation of SHEEC1 cells , and the low doses(0. 1μmol/ L or 0. 5μmol/ L) of As2O3 enhanced the mitotic index and DNA synthesis (in 0. 5μmol/ L) , which was determined by quantitative fluorescent cytomet ry. In t ransmitted elect ron microscope ( EM) , it was showed that SHEEC1 cells t reated with As2O3 in low doses displayed proliferative status with increasing mitochondria and poly2ribosomes in cytoplasm and multiple nucleoli in nucleus. Conclusion : The results suggest that As2O3 in low dosage promotes the proliferation of esophageal carcinoma cells and increament of DNA synthesis. As a conclusion , As2O3 has the characteristics of mitogenic effects.

Key words: Arsenite, esophageal carcinoma, cell proliferation, DNA synthesis