title: Mitochondrial and endoplasmic reticulum stress-induced apoptotic pathways are activated by 5-aminolevulinic acid-based photodynamic therapy in HL60 leukemia cells.
abstract: We studied the mechanism of the cytotoxic effects of 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT; induction with 1 mM ALA for 4 h followed by a blue light dose of 18 J/cm(2)) on the human promyelocytic leukemia cell line HL60 using biochemical and electron microscopy methods. The disruption of mitochondrial membrane potential, deltapsi(m), was paralleled by a decrease in ATP level, unmasking of the mitochondrial antigen 7A6, release of cytochrome c into the cytoplasm, activation of caspases 9 and 3 and cleavage of poly(ADP-ribose) polymerase (PARP). This was followed by DNA fragmentation. These data suggest that ALA-PDT activates the mitochondrial apoptotic pathway. The level of endoplasmic reticulum Ca(2+)-binding chaperones ERp57 and ERp72 and of anti-apoptotic proteins Bcl-2 and Bcl-x(L) was decreased whereas that of Ca(2+)-binding protein calmodulin and the stress protein HSP60 was elevated following ALA-PDT. Inhibition of the initiator caspase 9, execution caspase 3 and Ca(2+)-dependent protease m-calpain, did not prevent DNA fragmentation. We conclude that, in our in vitro model, ALA-based photodynamic treatment initiates several signaling processes in HL60 cells that lead to rapidly progressing apoptosis, which is followed by slow necrosis. Two apoptotic processes proceed in parallel, one representing the mitochondrial pathway, the other involving disruption of calcium homeostasis and activation of the endoplasmic reticulum stress-mediated pathway.
authors.affiliation: Department of Cellular Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 1, 12820 2 Prague, Czech Republic.
authors.forename: Dana
authors.initials: D
authors.lastname: Grebenová
authors.forename: Katerina
authors.initials: K
authors.lastname: Kuzelová
authors.forename: Karel
authors.initials: K
authors.lastname: Smetana
authors.forename: Michaela
authors.initials: M
authors.lastname: Pluskalová
authors.forename: Hana
authors.initials: H
authors.lastname: Cajthamlová
authors.forename: Iuri
authors.initials: I
authors.lastname: Marinov
authors.forename: Ota
authors.initials: O
authors.lastname: Fuchs
authors.forename: Josef
authors.initials: J
authors.lastname: Soucek
authors.forename: Petr
authors.initials: P
authors.lastname: Jarolím
authors.forename: Zbynek
authors.initials: Z
authors.lastname: Hrkal
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D021542:Amino Acids, Neutral / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000528:radiation effects* / Q000648:ultrastructure; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D018922:HL-60 Cells / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000528:radiation effects; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects*; D009363:Neoplasm Proteins / Q000378:metabolism; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology; D013312:Stress, Physiological / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology
chemical_list: D021542:Amino Acids, Neutral; D009363:Neoplasm Proteins; D017319:Photosensitizing Agents; C013809:5-aminovaleric acid; D000255:Adenosine Triphosphate