title: 5-Aminolevulinic acid-based photodynamic therapy suppressed survival factors and activated proteases for apoptosis in human glioblastoma U87MG cells.
abstract: Glioblastoma is the most common astrocytic brain tumor in humans. Current therapies for this malignancy are mostly ineffective. Photodynamic therapy (PDT), an exciting treatment strategy based on activation of a photosensitizer, has not yet been extensively explored for treating glioblastoma. We used 5-aminolevulinic acid (5-ALA) as a photosensitizer for PDT to induce apoptosis in human malignant glioblastoma U87MG cells and to understand the underlying molecular mechanisms. Trypan blue dye exclusion test showed a decrease in cell viability after exposure to increasing doses of 5-ALA for 4h followed by PDT with a broad spectrum blue light (400-550 nm) at a dose of 18J/cm(2) for 1h and then incubation at 37 degrees C for 4h. Following 0.5 and 1mM 5-ALA-based PDT (5-ALA-PDT), Wright staining and ApopTag assay showed occurrence of apoptosis morphologically and biochemically, respectively. After 5-ALA-PDT, down regulation of nuclear factor kappa B (NFkappaB) and baculovirus inhibitor-of-apoptosis repeat containing-3 (BIRC-3) protein indicated inhibition of survival signals. Besides, 5-ALA-PDT caused increase in Bax:Bcl-2 ratio and mitochondrial release of cytochrome c and apoptosis-inducing factor (AIF). Activation of calpain, caspase-9, and caspase-3 occurred in course of apoptosis. Calpain and caspase-3 activities cleaved alpha-spectrin at specific sites generating 145kD spectrin breakdown product (SBDP) and 120kD SBDP, respectively. The results suggested that 5-ALA-PDT induced apoptosis in U87MG cells by suppression of survival signals and activation of proteolytic pathways. Thus, 5-ALA-PDT can be an effective strategy for inducing apoptosis in glioblastoma.
authors.affiliation: Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas Street, Suite 323K, Charleston, SC 29425, USA.
authors.forename: Surajit
authors.initials: S
authors.lastname: Karmakar
authors.forename: Naren L
authors.initials: NL
authors.lastname: Banik
authors.forename: Sunil J
authors.initials: SJ
authors.lastname: Patel
authors.forename: Swapan K
authors.initials: SK
authors.lastname: Ray
mesh_terms: D000622:Aminolevulinic Acid / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D051033:Apoptosis Inducing Factor / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000528:radiation effects; D000075747:Baculoviral IAP Repeat-Containing 3 Protein; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D002154:Calpain / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D020169:Caspases / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D010447:Peptide Hydrolases / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D010778:Photochemotherapy / Q000379:methods*; D044767:Ubiquitin-Protein Ligases
chemical_list: D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D051034:Inhibitor of Apoptosis Proteins; D016328:NF-kappa B; D000622:Aminolevulinic Acid; C494832:BIRC3 protein, human; D000075747:Baculoviral IAP Repeat-Containing 3 Protein; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; D002154:Calpain; D020169:Caspases