Article

Imaging the molecular signatures of apoptosis and injury with radiolabeled annexin V

Department of Radiology/Division of Pediatric Radiology, Lucile Salter Packard Children's Hospital, Stanford, California, USA.
Proceedings of the American Thoracic Society 09/2009; 6(5):469-76. DOI: 10.1513/pats.200901-001AW
Source: PubMed

ABSTRACT Annexin V is a ubiquitous intracellular protein in humans that has a variety of intriguing characteristics, including a nanomolar affinity for the membrane-bound constitutive anionic phospholipid known as phosphatidylserine (PS). PS is selectively expressed on the surface of apoptotic or physiologically stressed cells. As such, radiolabeled forms of annexin V have been used in both animal models and human Phase I and Phase II trials to determine if this tracer can be employed as an early surrogate marker of therapeutic efficacy in NSCLC and non-Hodgkin's lymphoma. Many other pulmonary imaging applications of radiolabeled annexin V are also possible, including the detection and monitoring of active pulmonary inflammation and other pathophysiologic stressors in a variety of diseases. In this article, the salient molecular features of apoptosis (and other forms of cell death) that permits imaging with radiolabeled annexin V will be discussed. The latest results from Phase II imaging trials with NSCLC and non-Hodgkin's lymphoma will be also be detailed. Finally, the potential future application of this tracer for the imaging of other pulmonary pathologies will be outlined.

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Available from: Francis Blankenberg, Feb 24, 2015
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    • "PS externalization [44, 45] in the apoptotic cell membrane. Early in the apoptotic process there is a rapid redistribution and exposure of phosphatidylserine (PS) on the cell surface mediated by the enzyme scramblase. "
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    • "This reversible form of PS externalization is characterized by lower levels of PS exposure compared to apoptotic cells. PS exposure can thus not only be a sign for cells undergoing apoptosis, but also for (temporary) stressed cells with a high risk to become apoptotic [26]. Although PS externalization can be present in a variety of cells, apoptosis is regarded as the most important and abundant cellular process accompanied by the PS death phenotype. "
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