ABSTRACT
Objective: To investigate the pro-apoptotic effect of gambogenic acid (GNA) on human colonic carcinoma HCT116 cells, and to explore the possible molecular mechanism. Methods: MTT assay was performed to detect proliferation inhibition effect of GNA on HCT116 cells. After staining with DAPI, the pro-apoptotic effect of GNA on HCT116 cells was observed under a fluorescence microscope. The changes in cell cycle distribution of HCT116 cells induced by GNA were examined by FCM. The expressions of cyclin D1, cyclin E, P21, P27 and poly (ADP-ribose) polymerase (PARP) proteins in HCT116 cells were detected by Western blotting. Results: GNA exerted an significant inhibitory effect on HCT116 cell proliferation in a time-and dose-dependent manner, and it could induce the typical nuclear apoptotic morphology. Under a fluorescence microscope, DAPI staining results showed that GNA could obviously induce the apoptosis of HCT116 cells. FCM showed that GNA could significantly increase the percentage of cells at G0/G1 phase, whereas obviously decrease the percentage of cells at S phase, which indicated that the cell cycle was arrested at G 0/G1 phase. Western blotting analysis showed that GNA could efficiently down-regulate the expression levels of cyclin D1 and cyclin E proteins, whereas up-regulate the expression levels of P21 and P27 proteins, and also promote the cleavage of PARP. Conclusion: GNA can induce the cell cycle arrest at G0/G1 phase by down-regulating the expression levels of cyclin D1 and cyclin E, and up-regulating the expression levels of P21 and P27. Therefore, GNA can efficiently promote the cell proliferation inhibition and the apoptosis of HCT116 cells. Copyright© 2011 by TUMOR.