Aplidin® induces JNK-dependent apoptosis in human breast cancer cells via alteration of glutathione homeostasis, Rac1 GTPase activation, and MKP-1 phosphatase downregulation

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RESEARCH PRODUCT

Aplidin® induces JNK-dependent apoptosis in human breast cancer cells via alteration of glutathione homeostasis, Rac1 GTPase activation, and MKP-1 phosphatase downregulation

G Sáez-tormo María J. Muñoz-alonso Laura González-santiago Natasha Zarich L Goya Ana Cuadrado Yajaira Suárez A Iradi Jana V. Maier Alberto Muñoz Andrew C.b. Cato Teresa Martínez A Moorthy José M. Rojas

subject

rac1 GTP-Binding Protein Programmed cell death Small interfering RNA Glutathione reductase Down-Regulation Antineoplastic Agents Apoptosis Breast Neoplasms Cell Cycle Proteins Biology Peptides Cyclic Immediate-Early Proteins Membrane Potentials chemistry.chemical_compound Mice Downregulation and upregulation Depsipeptides Protein Phosphatase 1 Phosphoprotein Phosphatases Animals Homeostasis Humans Molecular Biology chemistry.chemical_classification Reactive oxygen species Glutathione Peroxidase Glutathione Disulfide JNK Mitogen-Activated Protein Kinases Protein phosphatase 1 Dual Specificity Phosphatase 1 Cell Biology Glutathione Cell biology Enzyme Activation Oxidative Stress Glutathione Reductase chemistry Mitochondrial Membranes Glutathione disulfide Calcium Protein Tyrosine Phosphatases Reactive Oxygen Species Copper HeLa Cells

description

Aplidin® is an antitumor agent in phase II clinical trials that induces apoptosis through the sustained activation of Jun N-terminal kinase (JNK). We report that Aplidin® alters glutathione homeostasis increasing the ratio of oxidized to reduced forms (GSSG/GSH). Aplidin® generates reactive oxygen species and disrupts the mitochondrial membrane potential. Exogenous GSH inhibits these effects and also JNK activation and cell death. We found two mechanisms by which Aplidin® activates JNK: rapid activation of Rac1 small GTPase and downregulation of MKP-1 phosphatase. Rac1 activation was diminished by GSH and enhanced by L-buthionine (SR)-sulfoximine, which inhibits GSH synthesis. Downregulation of Rac1 by transfection of small interfering RNA (siRNA) duplexes or the use of a specific Rac1 inhibitor decreased Aplidin®-induced JNK activation and cytotoxicity. Our results show that Aplidin® induces apoptosis by increasing the GSSG/GSH ratio, a necessary step for induction of oxidative stress and sustained JNK activation through Rac1 activation and MKP-1 downregulation.

year	journal	country	edition	language
2006-01-01	Cell Death and Differentiation

10.1038/sj.cdd.4401898 http://hdl.handle.net/10261/77449