Anti-proliferative and Apoptosis Induction Activity of Green Tea Polyphenols on Human Promyelocytic Leukemia HL-60 Cells

Background: Anti-proliferation and apoptosis inducing effects of green tea polyphenols (GTPs) were studied against human promyeolcytic leukemia HL-60 cells. Materials and Methods: Anti-proliferation activity of GTPs against HL-60 cells and cytotoxicity against normal cells, V79-4 were measured with the MTT assay. Nuclear fragmentation of GTP-treated cells was observed with a fluorescence microscope and flow-cytometric analysis was performed to observe the appearance of apoptotic bodies. Changes in apoptosis-related protein levels were investigated by Western blot analysis. Results: GTPs significantly reduced the HL-60 proliferation, however, they did not show significant inhibition in proliferation of normal V79-4 cells. GTP treatment induced apoptosis in HL-60 cells, evidenced by nuclei fragmentation and apoptotic body appearance. The expression level of Bcl-2 was decreased and caspase-3 was activated by GTP treatment. Conclusion: GTPs revealed anti-proliferative and apoptosis-inducing activity against HL-60 cells through the down-regulation of Bcl-2 and activation of caspase-3.