title: Catechin, green tea component, causes caspase-independent necrosis-like cell death in chronic myelogenous leukemia.
abstract: Management strategies of chronic phase chronic myelogenous leukemia (CML) have been revolutionized due to the discovery of a selective tyrosine kinase inhibitor, imatinib (Gleevec, STI571), which is substantially improving median survival. However, emergence of imatinib-resistance has put up a serious problem that requires novel treatment methods. Catechins, polyphenolic compounds in green tea, are gathering much attention due to their potential antitumor effects. So far (-)-epigallocatechin-3-gallate (EGCG), the most abundant component of catechin, has been shown to cause typical apoptosis in several tumor cell lines in most cases through activation of caspases. In this study, we showed that EGCG predominantly caused necrosis-like cell death via a caspase-independent mechanism in CML cells, K562 and C2F8, whereas imatinib induced the typical apoptotic cell death. Moreover, this caspase-independent cell death partially mediated the release of apoptosis-inducing factor, AIF, and serine protease, HtrA2/Omi, from the mitochondria to cytosol. In addition, EGCG enhanced the imatinib-induced cell death (P < 0.01) resulting in additive cell death in K562 cells and EGCG alone, effectively reduced the viability of imatinib-resistant K562 cells (P < 0.01). Catechin is a possible candidate for an antitumor agent that causes cell death in CML cells via a caspase-independent mechanism.
authors.affiliation: Laboratory of Tumor Cell Biology, Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, 4-6-1 Shiroganedai, Minato-ku, Tokyo, Japan.
authors.forename: Reo
authors.initials: R
authors.lastname: Iwasaki
authors.forename: Kinji
authors.initials: K
authors.lastname: Ito
authors.forename: Takaomi
authors.initials: T
authors.lastname: Ishida
authors.forename: Makoto
authors.initials: M
authors.lastname: Hamanoue
authors.forename: Souichi
authors.initials: S
authors.lastname: Adachi
authors.forename: Toshiki
authors.initials: T
authors.lastname: Watanabe
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sato
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D006801:Humans; D007124:Immunoenzyme Techniques; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D009336:Necrosis; D013347:Subcellular Fractions; D013662:Tea / Q000737:chemistry*
chemical_list: D016588:Anticarcinogenic Agents; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate; D020169:Caspases