No abstract

The present work was performed to investigate the effects of intermedeol on proliferation and differentiation of human leukemia-derived HL-60 cells as well as the underlying mechanisms for these effects. Intermedeol exhibited a potent antiproliferative activity against HL-60 cells. In addition, this compound was found to be a potent inducer for HL-60 cell differentiation as assessed by nitroblue tetrazolium reduction test, esterase activity assay, phagocytic activity assay, morphology change, and expression of CD14 and CD66b surface antigens. These results suggest that intermedeol induces differentiation of human leukemia cells to granulocytes and monocytes/macrophage lineage. Moreover, the expression level of c-myc was down-regulated during intermedeol-dependent HL-60 cell differentiation, whereas p21(CIP1) was up-regulated. Taken together, our results suggest that intermedeol may have potential as a therapeutic agent in human leukemia.

No abstract

Yomogin is an active compound isolated from Artemisia princep, a traditional Oriental medicinal herb, which has been shown to inhibit tumor cell proliferation. In this study, we investigated the effects of yomogin on the cytotoxicity, induction of apoptosis, and putative pathways of its actions in human promyelocytic leukemia cells. Yomogin-treated HL-60 cells displayed several features of apoptosis, including DNA fragmentation, formation of DNA ladders in agarose gel electrophoresis, and externalization of annexin-V targeted phosphatidylserine residues. We observed that yomogin caused activation of caspase-8, caspase-9, and caspase-3. A general caspase inhibitor (z-VAD-fmk), caspase-8 inhibitor (z-IETD-fmk) and caspase-3 inhibitor (z-DEVD-fmk), almost completely suppressed the yomogin-induced DNA fragmentation. We further demonstrated that yomogin induced Bid cleavage, mitochondrial translocation of Bax from the cytosol, and cytochrome c release from mitochondria in a caspase-8-dependent manner. Taken together, our data indicate that yomogin is a potent inducer of apoptosis and facilitates its activity via caspase-8 activation, Bid cleavage, Bax translocation to mitochondria, and subsequent release of cytochrome c into the cytoplasm, providing a potential mechanism for the anticancer activity of yomogin.