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Biotech / Medical : Cambridge Antibody Technology Group -- Ignore unavailable to you. Want to Upgrade?

To: scaram(o)uche who wrote (460)	2/19/2004 3:32:48 AM
From: tuck	Respond to of 625

>>Mol Cancer Ther. 2003;2:1273-1284 © 2003 American Association for Cancer Research Simultaneous activation of the intrinsic and extrinsic pathways by histone deacetylase (HDAC) inhibitors and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) synergistically induces mitochondrial damage and apoptosis in human leukemia cells Roberto R. Rosato, Jorge A. Almenara, Yun Dai and Steven Grant Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA Requests for Reprints: Steven Grant, Medical College of Virginia, Virginia Commonwealth University, MCV Station Box 230, Richmond, VA 23298. Phone: (804) 828-5211; Fax: (804) 828-8079. E-mail: stgrant@hsc.vcu.edu Interactions between histone deacetylase (HDAC) inhibitors and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), also known as Apo2 ligand, were examined in human leukemia cells (e.g., U937, Jurkat, and HL-60). Simultaneous exposure of cells to 100-ng/ml TRAIL with either 1-mM sodium butyrate or 2-µM suberoylanilide hydroxamic acid resulted in a striking increase in leukemic cell mitochondrial damage, caspase activation, and apoptosis. Lethal effects were significantly diminished in U937 cells ectopically expressing dominant-negative caspase-8, dominant-negative Fas-associated death domain, CrmA (receptor pathway), or Bcl-2 or Bcl-XL (mitochondrial pathway). Analysis of mitochondrial events in U937 cells exposed to TRAIL/HDAC inhibitors revealed enhanced Bid activation and Bax translocation, loss of mitochondrial membrane potential, and cytoplasmic release of cytochrome c, Smac/DIABLO, and apoptosis-inducing factor. No changes were observed in expression of FLICE-like inhibitory protein, TRAIL receptors, or reactive oxygen species generation. TRAIL/HDAC inhibitor-induced apoptosis triggered caspase-dependent cleavage of p21WAF1/CIP1; moreover, enforced expression of a nuclear localization signal deletant form of p21WAF1/CIP1 significantly diminished lethality. Lastly, p27KIP1, pRb, X-linked inhibitor of apoptosis, and Bcl-2 displayed extensive proteolysis. These findings indicate that coadministration of TRAIL with HDAC inhibitors synergistically induces apoptosis in human myeloid leukemia cells and provide further evidence that simultaneous activation of the extrinsic and intrinsic pathways in such cells leads to a dramatic increase in mitochondrial injury and activation of the caspase cascade. << Anyone know if this is being explored by either CAT or HGSI? Cheers, Tuck