Relationship between subcellular localisation of Foscan and caspase activation in photosensitised MCF-7 cells.
The present study investigates the relationship between the subcellular localisation of Foscan and intrinsic apoptotic pathway post Foscan-based photodynamic therapy (PDT). With this purpose, mammary carcinoma MCF-7 cells were incubated with Foscan for 3 or 24 h and then subjected to equitoxic light doses. Fluorescence microscopy revealed very good Foscan co-localization to endoplasmic reticulum (ER) and Golgi apparatus after 3 h incubation with MCF-7 cells. Progressive increase in incubation time shows leakage of Foscan from Golgi apparatus. Twenty-four hours incubation yielded a fluence-dependent enhanced induction of the ER-resident glucose-regulated protein 78 (Bip/GRP78), along with a weak mitochondrial damage, thus underscoring the ER as the main site of photodamage after prolonged incubation. Analysis of events implicated in apoptotic pathway after 24 h incubation demonstrated photodamage to Bcl-2 protein in total cellular extract, but not in the mitochondrial fraction. We further determined an increase in caspases-7 and -6 activation, which was strongly related to the expression of GRP78. The above findings demonstrate that Foscan localisation in ER improves the photoactivation of the caspase-7 apoptotic pathway, which is poorly related to mitochondrial damage.
Marchal
S
S
CRAN, Nancy University, CNRS UMR 7039, Centre Alexis Vautrin, Avenue de Bourgogne, 54511 Vandoeuvre-les-Nancy, France.
François
A
A
Dumas
D
D
Guillemin
F
F
Bezdetnaya
L
L
D001943:Breast Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism*; D045744:Cell Line, Tumor; D000091342:Endoplasmic Reticulum Chaperone BiP; D004789:Enzyme Activation; D005470:Fluorometry; D019254:Genes, bcl-2 / Q000528:radiation effects; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D006801:Humans; D008652:Mesoporphyrins / Q000493:pharmacokinetics* / Q000494:pharmacology; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects; D018832:Molecular Chaperones / Q000096:biosynthesis; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000493:pharmacokinetics* / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D013347:Subcellular Fractions / Q000378:metabolism
D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D008652:Mesoporphyrins; D018832:Molecular Chaperones; D017319:Photosensitizing Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D020169:Caspases; C072269:temoporfin