(-)-Epigallocatechin-3-O-gallate induces nonapoptotic cell death in leukemia cells independent of the 67 kDa laminin receptor.

The 67 kDa laminin receptor (67 LR) mediates (-)-epigallocatechin-3-O-gallate (1; EGCG)-67 LR direct action only at physiological concentrations. The relevancy of biological effects of 1 at physiological concentrations to 67 LR was investigated in myeloid and lymphoid leukemia cells using flow cytometric analysis. It was shown that physiological concentrations of 1 suppressed the cell growth of HL60 myeloid leukemia cells and Raji lymphoid leukemic cells independent of 67 LR expression. Moreover, there was no discernible change in the levels of intracellular reactive oxygen species, characteristics of apoptosis such as phosphatidylserine translocation and activated caspase-3. The activity of 1 at physiological concentrations does not depend on direct 67 LR-mediated actions, and this compound induces necrosis-like death of promyelocytic leukemia and non-Hodgkin's lymphoma cells.