Abstract: Objective To investigate the mechanism of a N-substituted isatin derivative (3MMIS) that can induce the cell cycle arrest and death of HepG2 cells. Methods Antitumor activity was detected by acid phosphatase (APA) method. The morphological changes of cells were observed under a light microscope at different time intervals. Flow cytometry was used to detect the cell cycle. Western blot was used to detect the effect of 3MMIS on cell cycle - related proteins. The effect of 3MMIS on microtubule assembly was detected . Results The IC50 of 3MMIS-treaded HepG2 cells was 0.4mg/L. Light microscopic observation showed that the cells through the drug treatment became rounded, up and developed a lot of vesicles in the cells. Flow cytometry showed that the cell cycle was blocked in M phase after drug action. Western blot showed abnormal expression of cycle related proteins.3MMIS treatment increased soluble and free tubulins but decreased insoluble and polymenized tubulins in HepG2 cells.Conclusion 3MMIS can induce cell death in HepG2 cells by affecting the polymeratin of tubulins and casing cell cycle arrest at the G2/M phase.

Key words: Isatin, autophagy, cycle arrest, microtubules