Green tea polyphenol epigallocatechin-O-gallate induces cell death by acid sphingomyelinase activation in chronic myeloid leukemia cells
An epidemiological study showed that green tea consumption is associated with a reduced risk of hematopoietic malignancy. The major green tea polyphenol epigallocatechin3-O-gallate (EGCG) is reported to have anticancer effects. Chronic myeloid leukemia (CML) is a major hematopoietic
malignancy characterized by expansion of myeloid cells. In the present study, we showed EGCG-induced acid sphingomyelinase (ASM) activation and lipid raft clustering in CML cells. The ASM inhibitor desipramine significantly reduced EGCG-induced cell death. Protein kinase Cδ is a
wellknown kinase that plays an important role in ASM activation. We observed EGCG-induced phosphorylation of protein kinase Cδ at Ser664. Importantly, EGCG-induced ASM activation was significantly reduced by pretreatment of CML cells with the soluble guanylate cyclase inhibitor
NS2028, suggesting that EGCG induced ASM activation through the cyclic guanosine monophosphate (cGMP)-dependent pathway. Indeed, pharmacological inhibition of a cGMP-negative regulator enhanced the anti-CML effect of EGCG. These results indicate that EGCG-induced cell death via the cGMP/ASM
pathway in CML cells.
Document Type: Research Article
Affiliations: Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan
Publication date: 01 January 2015
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