Photodynamic Therapy and Cell Death Pathways
Photodynamic therapy (PDT) is the term used to describe the irradiation of photosensitized cells or tissue with phototoxic consequences. This process can result in the rapid initiation of not only apoptosis, an irreversible death pathway, but also autophagy. The procedures described here are designed to characterize the correlation between the PDT dose vs. survival of cells in vitro, the apoptotic effects of photodamage, and the extent of an autophagic response. These are assessed by clonogenic assays, observation of condensed chromatin characteristic of apoptosis, activation of “executioner” caspases, and the autophagic flux as indicated by comparing accumulation of the LC3-II protein under conditions where processing of autophagosomes is retarded vs. is not retarded.
Key wordsApoptosis autophagy Bcl-2 Bid Bax photosensitization photodynamic therapy
The authors’ research is supported by NIH grant CA 23378 (to DK) and NIH grant CA 106491 (to NLO) from the National Cancer Institute, DHHS and by the State of Ohio Biomedical Research and Technology Transfer Trust TECH 05-063 (to NLO).
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