Background & objective: Isatin (ISA) is a natural material that exists in mammalian body fluids and tissues. ISA could inhibit the growth of tumors, but the mechanism remains unclear. This study aimed to explore the effects of ISA on the cell cycle and apoptosis of neuroblastoma cell line SH-SY5Y.
Methods: Fluorescent staining, flow cytometry, and Western blot were performed to analyze the cell cycle arrest and apoptosis of SH-SY5Y cells after treatment of ISA at different concentrations (0, 100, 200, 400 micromol/L).
Results: When treated with 400 micromol/L ISA for 48 h, SH-SY5Y cells showed typical apoptotic morphologic changes including chromatin condensation and DNA fragment. Along with the increase of ISA concentration, Bcl-2 expression was decreased, the ratio of Bcl-2 to Bax was significantly decreased (P<0.05). When treated with ISA (100, 200, 400 micromol/L) for 48 h, the positive rates of activated Caspase-3 in SH-SY5Y cells were significantly higher than that in control SH-SY5Y cells (19.28%, 25.88%, and 33.43% vs. 10.58%, P<0.05). Moreover, inhibitor of caspase-activated DNase (ICAD), the substrate of Caspase-3, was degraded. In addition, the proportion of SH-SY5Y cells at G1 phase was significantly increased with an apparent G1 phase arrest when treated with ISA (100, 200, 400 micromol/L) for 48 h. In the progress of cell cycle arrest induced by ISA, phosphorylated ERK and CDK1 expression were down-regulated (P<0.05).
Conclusion: ISA can induce apoptosis and G1 phase arrest in SH-SY5Y cells, possibly by decreasing Bcl-2/Bax, activating Caspase-3 and down-regulating the expression of phosphorylated ERK and CDK1.