(-)-Epigallocatechin gallate regulates CD3-mediated T cell receptor signaling in leukemia through the inhibition of ZAP-70 kinase

Jung Hyun Shim, Seok Choi Hong, Angelo Pugliese, Sung-Young Lee, Jung Il Chae, Young Choi Bu, Ann M. Bode, Zigang Dong

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Abstract

The ζ chain-associated 70-kDa protein (ZAP-70) of tyrosine kinase plays a critical role in T cell receptor-mediated signal transduction and the immune response. A high level of ZAP-70 expression is observed in leukemia, which suggests ZAP-70 as a logical target for immunomodulatory therapies. (-)-Epigallocatechin gallate (EGCG) is one of the major green tea catechins that is suggested to have a role as a preventive agent in cancer, obesity, diabetes, and cardiovascular disease. Here we identified ZAP-70 as an important and novel molecular target of EGCG in leukemia cells. ZAP-70 and EGCG displayed high binding affinity (Kd = 0.6207 μmol/liter), and additional results revealed that EGCG effectively suppressed ZAP-70, linker for the activation of T cells, phospholipase Cγ1, extracellular signaling-regulated kinase, and MAPK kinase activities in CD3-activated T cell leukemia. Furthermore, the activation of activator protein-1 and interleukin-2 induced by CD3 was dose-dependently inhibited by EGCG treatment. Notably, EGCG dose-dependently induced caspase-mediated apoptosis in P116.cl39 ZAP-70-expressing leukemia cells, whereas P116 ZAP-70-deficient cells were resistant to EGCG treatment. Molecular docking studies, supported by site-directed mutagenesis experiments, showed that EGCG could form a series of intermolecular hydrogen bonds and hydrophobic interactions within the ATP binding domain, which may contribute to the stability of the ZAP-70-EGCG complex. Overall, these results strongly indicated that ZAP-70 activity was inhibited specifically by EGCG, which contributed to suppressing the CD3-mediated T cell-induced pathways in leukemia cells.

Original languageEnglish (US)
Pages (from-to)28370-28379
Number of pages10
JournalJournal of Biological Chemistry
Volume283
Issue number42
DOIs
StatePublished - Oct 17 2008

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