Regulation of ROS-Dependent JNK Pathway by 2'-Hydroxycinnamaldehyde Inducing Apoptosis in Human Promyelocytic HL-60 Leukemia Cells.

The present study demonstrated that 2'-hydroxycinnamaldehyde (2'-HCA) induced apoptosis in human promyelocytic leukemia HL-60 cells through the activation of mitochondrial pathways including (1) translocation of Bim and Bax from the cytosol to mitochondria, (2) downregulation of Bcl-2 protein expression, (3) cytochrome c release into the cytosol, (4) loss of mitochondrial membrane potential (ΔΨm), and (5) caspase activation. 2'-HCA also induced the activation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase1/2 (ERK1/2) in HL-60 cells. The pharmacological and genetic inhibition of JNK effectively prevented 2'-HCA-induced apoptosis and activator protein-1 (AP-1)-DNA binding. In addition, 2'-HCA resulted in the accumulation of reactive oxygen species (ROS) and depletion of intracellular glutathione (GSH) and protein thiols (PSH) in HL-60 cells. NAC treatment abrogated 2'-HCA-induced JNK phosphorylation, AP-1-DNA binding, and Bim mitochondrial translocation, suggesting that oxidative stress may be required for 2'-HCA-induced intrinsic apoptosis. Xenograft mice inoculated with HL-60 leukemia cells demonstrated that the intraperitoneal administration of 2'-HCA inhibited tumor growth by increasing of TUNEL staining, the expression levels of nitrotyrosine and pro-apoptotic proteins, but reducing of PCNA protein expression. Taken together, our findings suggest that 2'-HCA induces apoptosis via the ROS-dependent JNK pathway and could be considered as a potential therapeutic agent for leukemia.

Eugenol isolated from the essential oil of Eugenia caryophyllata induces a reactive oxygen species-mediated apoptosis in HL-60 human promyelocytic leukemia cells.

Eugenol is a major component of essential oil isolated from the Eugenia caryophyllata (Myrtaceae), which has been widely used as a herbal drug. In this study, we investigated the effects of eugenol on the cytotoxicity, induction of apoptosis, and the putative pathways of its actions in human promyelocytic leukemia cells (HL-60) under the standard laboratory illumination. Eugenol-treated HL-60 cells displayed features of apoptosis including DNA fragmentation and formation of DNA ladders in agarose gel electrophoresis. We observed that eugenol transduced the apoptotic signal via ROS generation, thereby inducing mitochondrial permeability transition (MPT), reducing anti-apoptotic protein bcl-2 level, inducing cytochrome c release to the cytosol, and subsequent apoptotic cell death. Taken together, the present study demonstrated that ROS plays a critical role in eugenol-induced apoptosis in HL-60, and this is the first report on the mechanism of the anticancer effect of eugenol.

Saucernetin-8 isolated from Saururus chinensis induced the differentiation of human acute promyelocytic leukemia HL-60 cells.

The present work was performed to investigate the effects of saucernetin-8 on proliferation and differentiation of human leukemia HL-60 cells as well as the underlying mechanisms for these effects. Saucernetin-8 exhibited a potent antiproliferative activity against HL-60 cells. This compound was also found to be a potent inducer of differentiation in human leukemia derived HL-60 cells through the examination of differentiation markers, 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 saucernetin-8 induces the differentiation of human leukemia cells to granulocytes and monocytes/macrophages lineage. Moreover, DNA flow-cytometry indicated that saucernetin-8 induced a G1 phase arrest of HL-60 cells. The protein and mRNA expression levels of p21 were up-regulated during saucernetin-8-dependent HL-60 cell differentiation, whereas the level of c-myc was down-regulated. Taken together, our results suggest that saucernetin-8 may have potential as a therapeutic agent in human leukemia.