[Proliferative inhibition and apoptotic induction effects of crocin on human leukemia HL-60 cells and their mechanisms].

This study was to investigate the proliferative inhibition and apoptosis of human leukemia HL-60 cells induced by crocin and their possible mechanisms. The cell viability was tested by cell counting. The morphology of HL-60 cells was observed by fluorescence microscopy. The MTT assay was used to evaluate the inhibitory effect of crocin on the growth of HL-60 cells. Flow cytometry was used to measure the cell cycle. RT-PCR was used to detect bcl-2 and bax expression. The results indicated that the growth of HL-60 cells was inhibited remarkably in the dose and time dependent way. When the crocin concentration was higher than 5 mg/ml, the percentage of apoptotic HL-60 cells was not increased, on the contrary this percentage decreased, the cells manifested necrosis. Flow cytometry profiles revealed that cells were blocked in G₀/G₁ phase, the cell proliferation was inhibited obviously at 5 mg/ml. RT-PCR detection revealed that the expression of bcl-2 was down-regulated strikingly and bax was up-regulated. It is concluded that the crocin can inhibit the proliferation of HL-60 cells effectively, and block cells in G₀/G₁ phase. The mechanisms by which crocin induced apoptosis in HL-60 cells may be related to the inhibition of bcl-2 and activation of bax.