Catechin, a green tea component, rapidly induces apoptosis of myeloid leukemic cells via modulation of reactive oxygen species production in vitro and inhibits tumor growth in vivo

Background and Objectives. The aim of this study was to investigate the possibility of green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG) as a novel therapeutic agent for patients with myeloid leukemia. Design and Methods. We investigated the effects of EGCG on the induction of apoptosis in leukemic cells in vitro and in vivo. We further examined the molecular mechanisms of EGCG-induced apoptosis in myeloid leukemic cells. Results. EGCG rapidly induced apoptotic cell death in retinoic acid (RA)-resistant acute promyelocytic leukemia (APL), UF-1 cells within 3 h. EGCG-induced apoptosis in UF-1 cells was associated with the loss of mitochondrial transmembrane potentials (ΔΨ_m) and activation of caspase-3 and -9. Elevation of intracellular reactive oxygen species (ROS) production was also demonstrated during EGCG-induced apoptosis of UF-1 as well as fresh myeloid leukemic cells. In NOD/SCID mice transplanted with UF-1 cells, EGCG effectively inhibited tumor growth in vivo, and the number of mitoses among the cells significantly decreased in comparison to the number in control mouse cells. Interpretation and Conclusions. In summary, EGCG has potential as a novel therapeutic agent for myeloid leukemia via induction of apoptosis mediated by modification of the redox system.