Document Detail


Rapid induction of apoptosis in human keratinocytes with the photosensitizer QLT0074 via a direct mitochondrial action.
MedLine Citation:
PMID:  12766487     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
QLT0074 is a newly introduced, porphyrin-derivative for use in photodynamic therapy (PDT). In the current study, the intracellular distribution of QLT0074 and the mode of cell death induced by photosensitization with this compound in vitro were assessed for transformed human HaCaT keratinocytes. Fluorescence microscopy studies indicated a distribution of the drug to the cytoplasm, nuclear membrane and mitochondria of these cells. In the absence of light, QLT0074 produced no evidence of apoptosis-related biochemical changes or affected cell viability. When combined with blue light exposure, cytotoxicity was exerted in a QLT0074- and light-dose-related manner. Appearance of the mitochondrial protein cytochrome c in the cytosolic fraction and expression of the apoptosis-associated mitochondrial 7A6 antigen were demonstrable following photosensitization at nano-molar levels of QLT0074. Evidence of processing of the apoptosis-effector molecules caspase-3, -6, -7, -8 and -9 as well as cleavage of the caspase-3 substrate poly (ADP-ribose) polymerase (PARP) were demonstrable subsequent to cytochrome c release after PDT. Treatment with the anti-oxidant pyrrolidine dithiocarbamate (PDTC) inhibited cytochrome c release, caspase-3 activation and PARP cleavage associated with PDT thereby supporting the contention that QLT0074 induces apoptosis through the generation of reactive oxygen species upon light activation. QLT0074 is a potent photosensitizer with the capacity to directly initiate apoptosis by acting upon mitochondria.
Authors:
R Li; D J Bounds; D Granville; S H Ip; H Jiang; P Margaron; D W C Hunt
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Apoptosis : an international journal on programmed cell death     Volume:  8     ISSN:  1360-8185     ISO Abbreviation:  Apoptosis     Publication Date:  2003 Jun 
Date Detail:
Created Date:  2003-05-26     Completed Date:  2004-04-14     Revised Date:  2005-11-17    
Medline Journal Info:
Nlm Unique ID:  9712129     Medline TA:  Apoptosis     Country:  United States    
Other Details:
Languages:  eng     Pagination:  269-75     Citation Subset:  IM    
Affiliation:
Department of Preclinical Pharmacology, QLT Inc., 887 Great Northern Way, Vancouver, British Columbia, Canada V5T 4T5.
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MeSH Terms
Descriptor/Qualifier:
Antioxidants / pharmacology
Apoptosis / drug effects*,  radiation effects
Caspases / drug effects,  radiation effects
Cell Compartmentation / drug effects,  physiology
Cell Line, Transformed
Cytochromes c / drug effects,  radiation effects
Dose-Response Relationship, Drug
Humans
Keratinocytes / drug effects*,  metabolism,  radiation effects
Membrane Proteins / drug effects,  radiation effects
Mitochondria / drug effects*,  metabolism,  radiation effects
Photic Stimulation
Photochemotherapy
Photosensitizing Agents / radiation effects,  toxicity*
Poly(ADP-ribose) Polymerases
Porphyrins / pharmacology*,  radiation effects,  toxicity*
Proteins / drug effects,  radiation effects
Pyrrolidines / pharmacology
Reaction Time / drug effects,  radiation effects
Reactive Oxygen Species / metabolism
Thiocarbamates / pharmacology
Chemical
Reg. No./Substance:
0/Antioxidants; 0/Membrane Proteins; 0/Photosensitizing Agents; 0/Porphyrins; 0/Proteins; 0/Pyrrolidines; 0/QLT0074; 0/Reactive Oxygen Species; 0/Thiocarbamates; 0/antigen 7A6; 25769-03-3/pyrrolidine dithiocarbamic acid; 9007-43-6/Cytochromes c; EC 2.4.2.30/PARP1 protein, human; EC 2.4.2.30/Poly(ADP-ribose) Polymerases; EC 3.4.22.-/Caspases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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