Objective    To investigate the apoptosis-induced mechanism of crocin on bladder transitional cell carcinoma cell line T24.     Methods    MTT assay was used to evaluate the inhibitory effect of crocin on the growth of T24 cells. Microscope was used to observe the morphological changes. The changes of cell cycle were measured by flow cytometry. Annexin V-FITC/PI double labeling flow cytometry was used to determine the cell apoptotic percentage. RT-PCR and Western blot were used to detect Bcl-2 and Bax expressions.     Results    The growth of T24 cells was inhibited remarkably in a dose-dependent and time-dependent manner. Distinct morphological changes of cell apoptosis were observed. Flow cytometric pr

ofiles revealed that crocin led to increase of the cells in G

0

/G

1

phase and decrease of the cells in S phase

and the percentage of cell apoptosis was also increased. The mRNA and protein expressions of Bax increased and those of bcl-2 decreased.     Conclusion    Crocin exerts a fine inhibitory effect on the growth of human bladder transitional cell carcinoma cell line T24

maybe due to the apoptosis regulated by Bcl-2 and Bax pathway.