5-Aminolevulinic acid-based photodynamic therapy suppressed survival factors and activated proteases for apoptosis in human glioblastoma U87MG cells.
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.
Karmakar
Surajit
S
Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas Street, Suite 323K, Charleston, SC 29425, USA.
Banik
Naren L
NL
Patel
Sunil J
SJ
Ray
Swapan K
SK
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
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