Objective To study the mechanism of U937 cell (human histocytic lymphema) apoptosis induced by ATP. Methods ATP (0\^23?g/L) was added into U937 cell cultured medium as experiment group, no ATP adding group as the control. Using immunofluorescent cytochemistry method to demonstrat the expresses of Cx43, F\|actin, vinculin. Results ATP induced U937 cell to form apoptotic bodies. Expresses of Cx43, F\|actin, vinculin were increased in ATP treated U937 cells.Conclusion ATP could induce U937 cell apoptosis. Apoptotic bodies formed from ATP treated U937 cells was correlated closely with express of Cx43, F\|actin, vinculin, It indicats that Cx43, F\|actin, vinculin play important roles in U937 cell apoptosis induced by ATP.

This study was carried out to investigate the effects of ATP on cultured human stomach carcinoma MGC-803 cells. After ATP(0.16—0.23 mg/ml, 24—120 hrs)treatment, inhibition of cell growth rate was observed. The inhibition rate reached 80% after 96 hr exposure to ATP. At the same time, anti-tubulin immunofluorescent staining showed increase of organized microtubules (MT) in ATP-treated MGC-803 cells, in contrast with the poor MT immunofluorescence in control MGC-803 cells. By using rhodamie phalloidin combined staining, increased number of actin bundles, took the place of actin dots and patches which were seen in control MGC-803 cells. Immunofluorescent staining of fibronectin in ATP-treated MGC-803 cells was also increased evidently as compared with the control MGC-803 cells. Concomitant with the improvement of MT and stress fiber organization, the cell Concohas become more flattened. It appeared that the increase of MT and stress fibers was closely related to the recovery of cell morphology in ATP treated tumor cells. It is therefore concluded that ATP not only may inhibit tumor cell proliferation, but also may induce differentiation of cell morphology of tumor cells through its action on cytoskeletal structures.