Korean red ginseng extract induces apoptosis and decreases telomerase activity in human leukemia cells

Aim of this study: Korean red ginseng (KRG, Panax ginseng C.A. Meyer Radix rubra) has been used to treat various diseases including cancer. However, the molecular mechanisms responsible for KRG extract induced apoptosis and telomerase inhibition remain unclear. Materials and methods: The hot water extract from KRG was used to evaluate the mechanism of induction of apoptosis in U937 human leukemia cells and its effects on cyclooxgenase-2 (COX-2) and telomerase activity. Results: KRG extract treatment to U937 cells resulted in growth inhibition and induction of apoptosis in a concentration-dependent manner as measured by hemacytometer counts, MTT assay, fluorescence microscopy, agarose gel electrophoresis and flow cytometry analysis. The increase in apoptosis was associated with the down-regulation of antiapoptotic Bcl-2, Bcl-X-L, and IAPs family members, and the activation of caspase-3. KRG extract treatment also decreased the expression levels of COX-2 and inducible nitric oxide synthase. Furthermore. KRG extract treatment progressively down-regulated the expression of human telomerase reverse transcriptase, a main determinant of the telomerase enzymatic activity, with inhibiting the expression of c-Myc in a concentration-dependent manner. Conclusions: These results provide important new insights into the possible molecular mechanisms of the anticancer activity of KRG extract. (C) 2008 Elsevier Ireland Ltd. All rights reserved.