This project is designed to continue an exploration of early responses to photodynamic therapy (PDT), a procedure that involves irradiation of photosensitized cells and tissues. PDT circumvents many common drug- resistance mechanisms encountered in cancer chemotherapy and can lead to effective cancer control. PDT was initially (ca. 1975) thought to kill cells via membrane photodamage. We now know that the process is much more complex, with both apoptosis and autophagy plahying important roles. In this proposal we have identified three aims. We propose to: [1] explore the role of autophagy as a factor in cell death vs. survival in PDT;[2] characterize the effects of PDT on the endocytic pathway;[3] assess the contributions and roles of different reactive oxygen species on initiation of apoptosis and autophagy. Studies in the 1990s established apoptosis as a common mechanism of photokilling but not until 2006 was it realized that autophagy was also a component of survival vs. death decisions. Our knowledge of PDT responses continues to evolve and now includes such determinants of efficacy as canonical vs. non-canonical routes to autophagy and the evocation of apoptosis via indirect routes. While apoptosis is an irreversible route to death, autophagy can serves as a survival pathway, introducing a 'shoulder'on the dose-response curve, or as a death pathway. The result appears to depends on the PDT target, intrinsic cellular capacity for apoptosis and autophagy and other characteristics of the cell phenotype. An additional factor may be the pathway to autophagy elicited by PDT: canonical vs non-canonical. The latter is said to lead to cell death, but this may represent a special case. Protection from photokilling can occur even when autophagy is incomplete, i.e., without the fusion of auto- phagosomes with lysosomes followed by proteolysis of the encapsulated cargo. The nature of reactive oxygen species (ROS) induced by PDT also plays a role in promotion of apoptosis and autophagy. Enhanced H O 2 2 production was found to lead to the promotion of apoptosis, an effect we attribute to the long persistence of this species in the cellular environment. Moreover, both H O and !O S have been suggested as potential 2 2 2 initiating factors for autophagy. An exploration of the role of different ROS as determinants of PDT efficacy is therefore proposed. We have recently found that PDT evokes a hitherto unreported cellular response: impaired membrane trafficking leading to interference with the endocytic pathway. The implications of this effect remain to be explored.

Public Health Relevance

Significance: The ability of PDT to mediate direct photokilling of tumor cells, e.g., at surgical margins, can be an important aid in tumor eradication. Information on mechanisms of PDT-induced cell death pathways and their role in cancer control is also expected to assist in drug development and to provide a better under- standing of the role of death pathways in cancer control. Optimal targets for PDT remain to be identified

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA023378-32
Application #
8444598
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Wong, Rosemary S
Project Start
1983-08-01
Project End
2014-04-30
Budget Start
2013-05-01
Budget End
2014-04-30
Support Year
32
Fiscal Year
2013
Total Cost
$239,799
Indirect Cost
$82,037
Name
Wayne State University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
001962224
City
Detroit
State
MI
Country
United States
Zip Code
48202
Kessel, David; Evans, Conor L (2016) Promotion of Proapoptotic Signals by Lysosomal Photodamage: Mechanistic Aspects and Influence of Autophagy. Photochem Photobiol 92:620-3
Kessel, David (2016) Sub-cellular Targeting as a Determinant of the Efficacy of Photodynamic Therapy. Photochem Photobiol :
Kessel, David (2016) Photodynamic therapy: Promotion of efficacy by a sequential protocol. J Porphyr Phthalocyanines 20:302-306
Aggarwal, Neha; Santiago, Ann Marie; Kessel, David et al. (2015) Photodynamic therapy as an effective therapeutic approach in MAME models of inflammatory breast cancer. Breast Cancer Res Treat 154:251-62
Kessel, David (2015) Autophagic death probed by photodynamic therapy. Autophagy 11:1941-3
Kessel, David; Reiners Jr, John J (2015) Promotion of Proapoptotic Signals by Lysosomal Photodamage. Photochem Photobiol 91:931-6
Kessel, David (2015) Apoptosis and associated phenomena as a determinants of the efficacy of photodynamic therapy. Photochem Photobiol Sci 14:1397-402
Gibbs, Jaime H; Zhou, Zehua; Kessel, David et al. (2015) Synthesis, spectroscopic, and in vitro investigations of 2,6-diiodo-BODIPYs with PDT and bioimaging applications. J Photochem Photobiol B 145:35-47
Kessel, David (2014) Reversible effects of photodamage directed toward mitochondria. Photochem Photobiol 90:1211-3
Kessel, David; Reiners Jr, John J (2014) Enhanced efficacy of photodynamic therapy via a sequential targeting protocol. Photochem Photobiol 90:889-95

Showing the most recent 10 out of 127 publications