Difference in growth suppression and apoptosis induction of EGCG and EGC on human promyelocytic leukemia HL-60 cells

Growth suppression and apoptosis inducing effect of (−)-epigallocatechin 3-gallate (EGCG) and (−)-epigallocatechin (EGC) were studied against human promyeolcytic leukemia, HL-60 cells. EGCG showed higher growth suppression against HL-60 cells than EGC. IC 50 values for EGCG were 60.0 μM and EGC was 107.7 μM, respectively. Both EGCG and EGC induced apoptosis evidenced by nuclei fragmentation. Nuclear fragmentation was observed as a time-dependent manner and the extent of nuclear fragmentation was slightly higher in EGCG-treated cells than EGC-treated cells. The expression level of Bcl-2 was decreased and caspase-3 was activated by EGCG or EGC treatment. The extent in decrease of Bcl-2 and activation caspase-3 were more extensively occurred in EGCG-treated cells than in EGC-treated cells. These data corresponded to the growth suppression data. EGC showed no cytotoxicity to a normal V79-4 cell line and EGCG showed slight cytotoxicity at higher concentrations.