Carcinogenesis Advance Access published online on December 16, 2005
Carcinogenesis, doi:10.1093/carcin/bgi315
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1 Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, 28049 Madrid, Spain
* To whom correspondence should be addressed. There is a large body of clinical data documenting that most human carcinomas contain reduced levels of the catalytic subunit of the mitochondrial H+-ATP synthase. In colon and lung cancer this alteration correlates with a poor patient prognosis. Furthermore, recent findings in colon cancer cells indicate that down-regulation of the H+-ATP synthase is linked to the resistance of the cells to chemotherapy. However, the mechanism by which the H+-ATP synthase participates in cancer progression is unknown. In this work, we show that inhibitors of the H+-ATP synthase delay staurosporine-induced cell death in liver cells that are dependent on oxidative phosphorylation for energy provision whereas it has no effect on glycolytic cells. Efficient execution of cell death requires the generation of reactive oxygen species (ROS) controlled by the activity of the H+-ATP synthase in a process that is concurrent with the rapid disorganization of the cellular mitochondrial network. The generation of ROS after staurosporine treatment is highly dependent on the mitochondrial membrane potential and most likely caused by reverse electron flow to Complex I. The generated ROS promote the carbonylation and covalent modification of cellular and mitochondrial proteins. Inhibition of the activity of the H+-ATP synthase blunted ROS production, prevented the oxidation of cellular proteins and the modification of mitochondrial proteins, delaying the release of cyt c and the execution of cell death. The results in this work establish the down-regulation of the H+-ATP synthase, and thus of oxidative phosphorylation, as part of the molecular strategy adapted by cancer cells to avoid reactive oxygen species-mediated cell death. Furthermore, the results provide a mechanistic explanation to understand chemotherapeutic resistance of cancer cells that rely on glycolysis as main energy provision pathway.
Received November 15, 2005
Revised December 1, 2005
Accepted December 13, 2005
CANCER BIOLOGY
Efficient execution of cell death in non-glycolytic cells requires the generation of ROS controlled by the activity of mitochondrial H+-ATP synthase
Gema Santamaría 1 #,
Marta Martínez-Diez 1 #,
Isabel Fabregat 2,
and
José M. Cuezva 1 *
2 IDIBELL-Institut de Recerca Oncològica, 08907 L'Hospitalet, Barcelona, Spain
José M. Cuezva, E-mail: jmcuezva{at}cbm.uam.es
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Abstract
# Both authors equally contributed to this work.
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