Biological consequences of PDT: tying up the loose ends

David Kessel; Michelle Andrzejak; Michael Price

doi:10.1117/12.876209

8 February 2011 Biological consequences of PDT: tying up the loose ends

David Kessel, Michelle Andrzejak, Michael Price

Proceedings Volume 7886, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XX; 788602 (2011) https://doi.org/10.1117/12.876209
Event: SPIE BiOS, 2011, San Francisco, California, United States

Abstract

While many of the determinants of photodynamic tumor eradication have been identified, the story is not yet complete. Fluorescent probes for reactive oxygen species (ROS) are seldom specific, and the role of different ROS in apoptosis vs. autophagy are not fully delineated. Moreover, the conflicting roles of autophagy as both a death and a survival pathway remain to be explained. Most tissue-culture studies are carried out in 20% oxygen although this is far in excess of the environment of malignant cells in vivo. And while apoptotic and/or autophagic death appears to account for the lethal effects of PDT, an effect on membrane recycling has now been identified. In this report, we summarize some recent experiments designed to examine the specificity of fluorescent ROS probes. We also demonstrate the ability of hydrogen peroxide to accelerate the autophagic response to PDT in an adhering cell line, the 1c1c7 murine hepatoma. In this cell line, autophagy appears to be a pro-survival mechanism since a sub-line (KD) depleted in a critical autophagy protein (atg7) was more responsive to PDT than wild-type (WT) cells. There are clearly multiple determinants of direct tumor cell kill by PDT that depend on the PDT target, the ROS produced and phenotypic variations.

Citation Download Citation

David Kessel, Michelle Andrzejak, and Michael Price "Biological consequences of PDT: tying up the loose ends", Proc. SPIE 7886, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XX, 788602 (8 February 2011); https://doi.org/10.1117/12.876209

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