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Proceedings Paper

Photodynamic therapy: first responses
Author(s): David Kessel; Michael Price
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Paper Abstract

During the irradiation of photosensitized cells, reactive oxygen species (ROS) are generated leading to a variety of effects including apoptosis and autophagy. These responses can occur within minutes after irradiation. Apoptosis is an irreversible pathway to death that can be triggered by release of cytochrome c from mitochondria. Autophagy is a recycling process that can occur as a result of Bcl-2 photodamage or as a response to organelle disruption. We have reported that autophagy is associated with a 'shoulder' on the PDT dose-response curve. Although predominantly a survival pathway, autophagy can also play a role in cell death if cells attempt an excessive amount of recycling, beyond their ability to repair photodamage. Recent studies have been directed toward assessing the role of different ROS in the immediate response to PDT. While singlet oxygen is considered to be the major phototoxic ROS, it appears that catalase activity is also a determinant of the apoptotic response and that H2O2OH can amplify the effects of singlet oxygen. An early response to PDT also involves inhibition of membrane trafficking systems related to the endocytic pathway. The extent and nature of these early responses appear to be among the determinants of subsequent tumor eradication.

Paper Details

Date Published: 13 July 2009
PDF: 7 pages
Proc. SPIE 7380, Photodynamic Therapy: Back to the Future, 738009 (13 July 2009); doi: 10.1117/12.822140
Show Author Affiliations
David Kessel, Wayne State Univ. (United States)
Michael Price, Wayne State Univ. (United States)

Published in SPIE Proceedings Vol. 7380:
Photodynamic Therapy: Back to the Future
David H. Kessel, Editor(s)

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