ARSENITE INHIBITS MITOTIC DIVISION AND PERTURBS SPINDLE DYNAMICS IN HELA S3 CELLS

Arsenical compounds, known to be human carcinogens, were shown to dist urb cell cycle progression and induce cytogenetic alterations in a var iety of cell systems. We report here that a 24 h treatment of arsenite induced mitotic accumulation in human cell lines. HeLa S3 and KB cell s were most susceptible: 35% of the total cell population was arrested at the mitotic stage after treatment with 5 mu M sodium arsenite in H eLa S3 cells and after 10 mu M in KB cells. Under a microscope, we obs erved abnormal mitotic figures in arsenite-arrested mitotic cells, inc luding deranged chromosome congression, elongated polar distance of mi totic spindle, and enhanced microtubule immunofluorescence. The spindl e microtubules of arsenite-arrested mitotic cells were more resistant to nocodazole-induced dissolution than those of control mitotic cells. According to turbidity assay, arsenite at concentrations below 100 mu M significantly enhanced polymerization of tubulins, Since spindle dy namics play a crucial role in mitotic progression, our results suggest that arsenite-induced mitotic arrest may be due to arsenite's effects on attenuation of spindle dynamics.