5-ALA-PDT induces RIP3-dependent necrosis in glioblastoma.
Glioblastoma constitute the most frequent and deadliest brain tumors of astrocytic origin. They are resistant to all current therapies and are associated with a high rate of recurrence. Glioblastoma were previously shown to respond to treatments by 5-aminolevulinic acid (5-ALA)-based photodynamic therapy (PDT) mainly by activating a necrotic type of cell death. The receptor-interacting protein 3 (RIP3) has recently been outlined as a key mediator of this caspase-independent form of programmed cell death. In the present study, we analyzed the necrotic mechanism induced by 5-ALA-PDT in human glioblastoma cells and explored the role of RIP3 in this context. Our results show that PDT-induced necrosis is dependent on RIP3, which forms aggregates and colocalizes with RIP1 following photosensitization. We demonstrate that PDT-mediated singlet oxygen production is the cause of RIP3-dependent necrotic pathway activation. We also prove that PDT induces the formation of a pro-necrotic complex containing RIP3 and RIP1 but lacking caspase-8 and FADD, two proteins usually part of the necrosome when TNF-α is used as a stimulus. Thus, we hypothesize that PDT might lead to the formation of a different necrosome whose components, besides RIP1 and RIP3, are still unknown. In most cases, glioblastoma are characterized by a constitutive activation of NF-κB. This factor is a key regulator of various processes, such as inflammation, immune response, cell growth or apoptosis. Its inhibition was shown to further sensitize glioblastoma cells to PDT-induced necrosis, however, no difference in RIP3 upshift or aggregation could be observed when NF-κB was inhibited.
Virology and Immunology Unit, GIGA-Research, University of Liège, Belgium.
Isabelle
I
Coupienne
Grégory
G
Fettweis
Noemí
N
Rubio
Patrizia
P
Agostinis
Jacques
J
Piette
D000622:Aminolevulinic Acid / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis; D053181:Caspase 8 / Q000378:metabolism; D045744:Cell Line, Tumor; D053200:Fas-Associated Death Domain Protein / Q000378:metabolism; D005909:Glioblastoma / Q000188:drug therapy; D006801:Humans; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D009336:Necrosis / Q000139:chemically induced; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D026082:Singlet Oxygen / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
C119724:AGFG1 protein, human; D053200:Fas-Associated Death Domain Protein; D016328:NF-kappa B; D028861:Nuclear Pore Complex Proteins; D017319:Photosensitizing Agents; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D014409:Tumor Necrosis Factor-alpha; D026082:Singlet Oxygen; D000622:Aminolevulinic Acid; C119705:RIPK3 protein, human; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D053181:Caspase 8