Apoptosis Of Leukeamia Cell Lines Induced By Polyphylloside â…¡ And Its Molecular Mechanisms

AIM: To explore the apoptosis of leukeamia cell lines induced by Polyphylloside II and its molecular mechanisms. METHODS: Morphological changes in K562 and HL60 cells were observed under phase-contrast microscope and fluorescence microscope. The cell cycle distributions , apoptosis and phosphatidylserine(PS) transpositions were detected by flow cytometry(FCM). Expressions of Bcl-2 , Bax and Fas proteins were analyzed with immunohistochemical staining in K562 cells. RESULTS: â‘ K562 and HL60 cells treated with 5ug/ml Polyphylloside II for 24 hours showed morphological characteristics of apoptosis, such as inequality of cell size, the cleavage and pyknosis of cell nuclei and nuclear chromatin condensation. â‘¡Treatment of K562 and HL60 cells with 5ug/ml Polyphylloside II for 24, 48 and 72 hours caused subdiploid peak, which was increased time-dependently. The cell cycle distributions by FCM showed that K562 cells were blocked in G₂/M phase and that HL60 cells in S phase.â‘¢11. 2 percent preapoposis of K562 cells were induced by 24 hours exposure to 5ug/ml Polyphylloside II while positive control cells had only 3.55 percent. â‘£The baseline Bcl-2 proteins expression was low while Bax and Fas proteins had no marked changes. CONCLUSION: Polyphylloside II could induce apoptosis of K562 and HL60 cells and the effects of apoptosis on K562 cells may be correlated with the down-regulation of anti-apoptotic Bcl-2 proteins.