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Proceedings Paper

Pheophorbide a mediated photodynamic therapy against human epidermoid carcinoma cells (A431)
Author(s): Yi-Chun Chen; Wen-Tyng Li
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Paper Abstract

The objective of this study was to characterize the death mechanism of human epidermoid carcinoma cells (A431) triggered by photodynamic therapy (PDT) with pheophorbide a. First of all, significant inhibition on the survival of A431 cells (< 20 %) was observed when an irradiation dose of 5.1 J/cm2 combined with 125 ng/ml of pheophorbide a was applied. Survival rate of human keratinocyte cells was over 70 % under the same PDT parameters, suggesting that pheophorbide a killed cancer cells selectively. Mitochondria were the main target sites where pheophorbide a accumulated. Formation of reactive oxygen species (ROS) was detected after PDT. Addition of antioxidant N-Acetyl cysteine prevented ROS production and increased cell survival thereafter. The decrease in cellular ATP level was also observed at 6 hrs after PDT. Typical apoptotic cellular morphology and a collapse of mitochondrial membrane potential occurred after PDT. The loss of mitochondrial membrane potential led to the release of cytochrome c from the mitochondria to the cytosol, followed by activation of caspase-9 and caspase-3. The activation of caspase-3 resulted in poly(ADP-ribose) polymerase (PARP) cleavage in A431 cells, followed by DNA fragmentation. In conclusion, the results demonstrated that pheophorbide a possessed photodynamic action against A431 cells, mainly through apoptosis mediated by mitochondrial intrinsic pathway triggered by ROS.

Paper Details

Date Published: 10 February 2011
PDF: 8 pages
Proc. SPIE 7886, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XX, 788616 (10 February 2011); doi: 10.1117/12.874978
Show Author Affiliations
Yi-Chun Chen, Chung-Yuan Christian Univ. (Taiwan)
Wen-Tyng Li, Chung-Yuan Christian Univ. (Taiwan)

Published in SPIE Proceedings Vol. 7886:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XX
David H. Kessel; Tayyaba Hasan, Editor(s)

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