title: RIP1 and RIP3 complex regulates radiation-induced programmed necrosis in glioblastoma.
abstract: Radiation-induced necrosis (RN) is a relatively common side effect of radiation therapy for glioblastoma. However, the molecular mechanisms involved and the ways RN mechanisms differ from regulated cell death (apoptosis) are not well understood. Here, we compare the molecular mechanism of cell death (apoptosis or necrosis) of C6 glioma cells in both in vitro and in vivo (C6 othotopically allograft) models in response to low and high doses of X-ray radiation. Lower radiation doses were used to induce apoptosis, while high-dose levels were chosen to induce radiation necrosis. Our results demonstrate that active caspase-8 in this complex I induces apoptosis in response to low-dose radiation and inhibits necrosis by cleaving RIP1 and RI. When activation of caspase-8 was reduced at high doses of X-ray radiation, the RIP1/RIP3 necrosome complex II is formed. These complexes induce necrosis through the caspase-3-independent pathway mediated by calpain, cathepsin B/D, and apoptosis-inducing factor (AIF). AIF has a dual role in apoptosis and necrosis. At high doses, AIF promotes chromatinolysis and necrosis by interacting with histone H2AX. In addition, NF-κB, STAT-3, and HIF-1 play a crucial role in radiation-induced inflammatory responses embedded in a complex inflammatory network. Analysis of inflammatory markers in matched plasma and cerebrospinal fluid (CSF) isolated from in vivo specimens demonstrated the upregulation of chemokines and cytokines during the necrosis phase. Using RIP1/RIP3 kinase specific inhibitors (Nec-1, GSK'872), we also establish that the RIP1-RIP3 complex regulates programmed necrosis after either high-dose radiation or TNF-α-induced necrosis requires RIP1 and RIP3 kinases. Overall, our data shed new light on the relationship between RIP1/RIP3-mediated programmed necrosis and AIF-mediated caspase-independent programmed necrosis in glioblastoma.
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA. dasa@musc.edu.
authors.forename: Arabinda
authors.initials: A
authors.lastname: Das
authors.affiliation: Department of Radiation Oncology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: McDonald
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.
authors.forename: Yaenette N
authors.initials: YN
authors.lastname: Dixon-Mah
authors.affiliation: Department of Radiation Oncology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Dustin J
authors.initials: DJ
authors.lastname: Jacqmin
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.
authors.forename: Vikram N
authors.initials: VN
authors.lastname: Samant
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.
authors.forename: William A
authors.initials: WA
authors.lastname: Vandergrift
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Lindhorst
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.
authors.forename: David
authors.initials: D
authors.lastname: Cachia
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.
authors.forename: Abhay K
authors.initials: AK
authors.lastname: Varma
authors.affiliation: Department of Radiation Oncology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Vanek
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.|Ralph H. Johnson VA Medical Center, Charleston, SC, USA.
authors.forename: Naren L
authors.initials: NL
authors.lastname: Banik
authors.affiliation: Department of Radiation Oncology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Jenrette
authors.affiliation: Department of Neurology and Northwestern Brain Tumor Institute, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Jeffery J
authors.initials: JJ
authors.lastname: Raizer
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.|Department of Neurological Surgery, Ohio State University Wexner Medical College, Columbus, OH, 43210, USA.
authors.forename: Pierre
authors.initials: P
authors.lastname: Giglio
authors.affiliation: Department of Neurosurgery (Divisions of Neuro-oncology) and MUSC Brain and Spine Tumor Program CSB 310, Medical University of South Carolina, Charleston, SC, 29425, USA.
authors.forename: Sunil J
authors.initials: SJ
authors.lastname: Patel
mesh_terms: D000818:Animals; D017209:Apoptosis; D014408:Biomarkers, Tumor / Q000378:metabolism; D015153:Blotting, Western; D020169:Caspases; D049109:Cell Proliferation; D005720:Gamma Rays / Q000009:adverse effects*; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D007124:Immunoenzyme Techniques; D008297:Male; D009336:Necrosis / Q000209:etiology / Q000378:metabolism* / Q000473:pathology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011832:Radiation Injuries / Q000209:etiology / Q000378:metabolism* / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D014408:Biomarkers, Tumor; D017346:Protein Serine-Threonine Kinases; C586536:RIPK1 protein, rat; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C582791:Ripk3 protein, rat; D020169:Caspases
keywords: Apoptosis; Glioblastoma; RIP; Radiation necrosis