TIEG1 induces apoptosis through mitochondrial apoptotic pathway and promotes apoptosis induced by homoharringtonine and velcade

Overexpression of TGF beta inducible early gene (TIEG1) mimics TGF beta action and induces apoptosis. In this study, we found that TIEG I was significantly up-regulated during apoptosis induced by homoharringtonine or velcade. Overexpression of TIEG1 could induce apoptosis in K562 cells and promote apoptosis induced by HHT or velcade. TIEG1-induced apoptosis was shown to involve Bax and Bim up-regulation, Bcl-2 and Bcl-XL down-regulation, release of cytochrome c from mitochondria into the cytosol, activation of caspase 3 and disruption of the mitochondrial membrane potential (Delta psi m). We concluded that TIEG1 is a key regulator which induces and promotes apoptosis through the mitochondrial apoptotic pathway. (c) 2007 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.