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Progressive multifocal leukoencephalopathy (PML) is an opportunistic infectious demyelinating disease of the central nervous system caused by JC polyomavirus predominantly affecting immunocompromised individuals. Nowadays, HIV, hematological malignancies and iatrogenic immune suppression account for most PML cases. For unknown reasons, spinal cord is classically protected from PML lesions. Here, we report the course of a patient harboring spinal cord lesions in the context of PML with immune reconstitution inflammatory syndrome and review the eight other cases reported in the literature so far. Then, we discuss the evolving spectrum of PML over recent years, potentially making its diagnosis more challenging.
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BACKGROUND: Synovial tissue research has become widely developed in several rheumatology centres, however, large discrepancies exist in the way synovial tissue is handled and, more specifically, how data pertaining to biopsy procedure, quality check and experimental results are reported in the literature. This heterogeneity hampers the progress of research in this rapidly expanding field. In that context, under the umbrella of European Alliance of Associations for Rheumatology, we aimed at proposing points to consider (PtC) for minimal reporting requirements in synovial tissue research. METHODS: Twenty-five members from 10 countries across Europe and USA met virtually to define the key areas needing evaluation and formulating the research questions to inform a systematic literature review (SLR). The results were presented during a second virtual meeting where PtC were formulated and agreed. RESULTS: Study design, biopsy procedures, tissue handling, tissue quality control and tissue outcomes (imaging, DNA/RNA analysis and disaggregation) were identified as important aspects for the quality of synovial tissue research. The SLR interrogated four databases, retrieved 7654 abstracts and included 26 manuscripts. Three OPs and nine PtC were formulated covering the following areas: description of biopsy procedure, overarching clinical design, patient characteristics, tissue handling and processing, quality control, histopathology, transcriptomic analyses and single-cell technologies. CONCLUSIONS: These PtC provide guidance on how research involving synovial tissue should be reported to ensure a better evaluation of results by readers, reviewers and the broader scientific community. We anticipate that these PtC will enable the field to progress in a robust and transparent manner over the coming years.
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Reumatologia , Humanos , Membrana Sinovial/patologia , Biópsia/métodos , Europa (Continente)RESUMO
An inflamed synovial membrane plays a major role in joint destruction and is characterized by immune cells infiltration and fibroblast proliferation. This proteomic study considers the inflammatory process at the molecular level by analyzing synovial biopsies presenting a histological inflammatory continuum throughout different arthritis joint diseases. Knee synovial biopsies were obtained from osteoarthritis (OA; n = 9), chronic pyrophosphate arthropathy (CPPA; n = 7) or rheumatoid arthritis (RA; n = 8) patients. The histological inflammatory score was determined using a semi-quantitative scale based on synovial hyperplasia, lymphocytes, plasmocytes, neutrophils and macrophages infiltration. Proteomic analysis was performed by liquid chromatography-mass spectrometry (LC-MS/MS). Differentially expressed proteins were confirmed by immunohistochemistry. Out of the 1871 proteins identified and quantified by LC-MS/MS, 10 proteins (LAP3, MANF, LCP1, CTSZ, PTPRC, DNAJB11, EML4, SCARA5, EIF3K, C1orf123) were differentially expressed in the synovial membrane of at least one of the three disease groups (RA, OA and CPPA). Significant increased expression of the seven first proteins was detected in RA and correlated to the histological inflammatory score. Proteomics is therefore a powerful tool that provides a molecular pattern to the classical histology usually applied for synovitis characterization. Except for LCP1, CTSZ and PTPRC, all proteins have never been described in human synovitis.
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Artrite/imunologia , Artrite/patologia , Proteínas/metabolismo , Membrana Sinovial/imunologia , Membrana Sinovial/patologia , Idoso , Artrite Reumatoide/imunologia , Artrite Reumatoide/patologia , Biópsia , Condrocalcinose , Feminino , Humanos , Imuno-Histoquímica , Masculino , Espectrometria de Massas , Pessoa de Meia-Idade , ProteômicaRESUMO
Pancreatic ductal adenocarcinoma (PDAC) remains a deadly malignancy with no efficient therapy available up-to-date. Glycolysis is the main provider of energetic substrates to sustain cancer dissemination of PDAC. Accordingly, altering the glycolytic pathway is foreseen as a sound approach to trigger pancreatic cancer regression. Here, we show for the first time that high transforming growth factor beta-induced (TGFBI) expression in PDAC patients is associated with a poor outcome. We demonstrate that, although usually secreted by stromal cells, PDAC cells synthesize and secrete TGFBI in quantity correlated with their migratory capacity. Mechanistically, we show that TGFBI activates focal adhesion kinase signaling pathway through its binding to integrin αVß5, leading to a significant enhancement of glycolysis and to the acquisition of an invasive phenotype. Finally, we show that TGFBI silencing significantly inhibits PDAC tumor development in a chick chorioallantoic membrane assay model. Our study highlights TGFBI as an oncogenic extracellular matrix interacting protein that bears the potential to serve as a target for new anti-PDAC therapeutic strategies.
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Carcinoma Ductal Pancreático/patologia , Movimento Celular , Proteínas da Matriz Extracelular/metabolismo , Glicólise , Neoplasias Pancreáticas/patologia , Fator de Crescimento Transformador beta1/metabolismo , Animais , Carcinoma Ductal Pancreático/metabolismo , Linhagem Celular Tumoral , Embrião de Galinha , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Inativação Gênica , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Neoplasias Pancreáticas/metabolismo , Receptores de Vitronectina/metabolismo , Transdução de Sinais , Frações Subcelulares/metabolismo , Análise de Sobrevida , Fator de Crescimento Transformador beta1/genéticaRESUMO
BACKGROUND: Breast cancer is a leading malignancy affecting the female population worldwide. Most morbidity is caused by metastases that remain incurable to date. TGF-ß1 has been identified as a key driving force behind metastatic breast cancer, with promising therapeutic implications. METHODS AND FINDINGS: Employing immunohistochemistry (IHC) analysis, we report, to our knowledge for the first time, that asporin is overexpressed in the stroma of most human breast cancers and is not expressed in normal breast tissue. In vitro, asporin is secreted by breast fibroblasts upon exposure to conditioned medium from some but not all human breast cancer cells. While hormone receptor (HR) positive cells cause strong asporin expression, triple-negative breast cancer (TNBC) cells suppress it. Further, our findings show that soluble IL-1ß, secreted by TNBC cells, is responsible for inhibiting asporin in normal and cancer-associated fibroblasts. Using recombinant protein, as well as a synthetic peptide fragment, we demonstrate the ability of asporin to inhibit TGF-ß1-mediated SMAD2 phosphorylation, epithelial to mesenchymal transition, and stemness in breast cancer cells. In two in vivo murine models of TNBC, we observed that tumors expressing asporin exhibit significantly reduced growth (2-fold; p = 0.01) and metastatic properties (3-fold; p = 0.045). A retrospective IHC study performed on human breast carcinoma (n = 180) demonstrates that asporin expression is lowest in TNBC and HER2+ tumors, while HR+ tumors have significantly higher asporin expression (4-fold; p = 0.001). Assessment of asporin expression and patient outcome (n = 60; 10-y follow-up) shows that low protein levels in the primary breast lesion significantly delineate patients with bad outcome regardless of the tumor HR status (area under the curve = 0.87; 95% CI 0.78-0.96; p = 0.0001). Survival analysis, based on gene expression (n = 375; 25-y follow-up), confirmed that low asporin levels are associated with a reduced likelihood of survival (hazard ratio = 0.58; 95% CI 0.37-0.91; p = 0.017). Although these data highlight the potential of asporin to serve as a prognostic marker, confirmation of the clinical value would require a prospective study on a much larger patient cohort. CONCLUSIONS: Our data show that asporin is a stroma-derived inhibitor of TGF-ß1 and a tumor suppressor in breast cancer. High asporin expression is significantly associated with less aggressive tumors, stratifying patients according to the clinical outcome. Future pre-clinical studies should consider options for increasing asporin expression in TNBC as a promising strategy for targeted therapy.
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Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Proteínas da Matriz Extracelular/farmacologia , Animais , Biomarcadores Tumorais/metabolismo , Western Blotting , Ensaio de Imunoadsorção Enzimática , Feminino , Fatores de Crescimento de Fibroblastos/metabolismo , Fatores de Crescimento de Fibroblastos/farmacologia , Fibroblastos/metabolismo , Regulação Neoplásica da Expressão Gênica , Xenoenxertos , Humanos , Interleucina-1beta/farmacologia , Camundongos , Pessoa de Meia-Idade , Prognóstico , Reação em Cadeia da Polimerase em Tempo Real , Estudos Retrospectivos , Análise de Sobrevida , Fator de Crescimento Transformador beta/farmacologia , Células Tumorais CultivadasRESUMO
Functional targeted therapy has unfortunately failed to improve the outcome of glioblastoma patients. Success stories evidenced by the use of antibody-drug conjugates in other tumor types are encouraging, but targets specific to glioblastoma and accessible through the bloodstream remain scarce. In the current work, we have identified and characterized novel and accessible proteins using an innovative proteomic approach on six human glioblastomas; the corresponding data have been deposited in the PRIDE database identifier PXD001398. Among several clusters of uniquely expressed proteins, we highlight collagen-VI-alpha-1 (COL6A1) as a highly expressed tumor biomarker with low levels in most normal tissues. Immunohistochemical analysis of glioma samples from 61 patients demonstrated that COL6A1 is a significant and consistent feature of high-grade glioma. Deposits of COL6A1 were evidenced in the perivascular regions of the tumor-associated vasculature and in glioma cells found in pseudopalisade structures. Retrospective analysis of public gene-expression data sets from over 300 glioma patients demonstrated a significant correlation of poor patient outcome and high COL6A1 expression. In a proof-of-concept study, we use chicken chorioallantoic membrane in vivo model to show that COL6A1 is a reachable target for IV-injected antibodies. The present data warrant further development of human COL6A1 antibodies for assessing the quantitative biodistribution in the preclinical tumor models.
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Biomarcadores Tumorais/metabolismo , Neoplasias Encefálicas/metabolismo , Colágeno Tipo VI/metabolismo , Glioblastoma/metabolismo , Proteômica/métodos , Animais , Western Blotting , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Embrião de Galinha , Membrana Corioalantoide/metabolismo , Membrana Corioalantoide/patologia , Cromatografia Líquida de Alta Pressão , Glioblastoma/patologia , Humanos , Imuno-Histoquímica , Estimativa de Kaplan-Meier , Microscopia de Fluorescência , Prognóstico , Espectrometria de Massas em Tandem , Transplante HeterólogoRESUMO
Introduction: Brain abscess is the most common focal infectious neurological injury. Until the nineteenth century this condition was fatal, however the development of neuroimaging for early diagnosis, neurosurgery and antibiotic therapy in the twentieth century has led to new therapeutic strategies decreasing mortality from 50â% in the 1970s to less than 10â% nowadays. In this context we report a case of brain abscess with a dental origin. Case report: A immunocompetent man without any addiction presented to the emergency department with dysarthria and frontal headache at home. The clinical examination was normal. Further investigations revealed a polymicrobial brain abscess as a consequence of an ear, nose or throat (ENT) infection with locoregional extension with a dental starting point involving Actinomyces israelii and Fusobacterium nucleatum . In spite of a rapid diagnosis and a neurosurgical management associated with an optimal treatment by a dual therapy made of ceftriaxone and metronidazole the patient unfortunately died. Conclusion: This case report shows that despite a low incidence and a good prognosis following the diagnosis, brain abscesses can lead to patient's death. Thereby, when the patient's condition and urgency allow, a thorough dental examination of patients with neurological signs following the recommendations would improve the diagnosis made by the clinician. The use of microbiological documentation, the respect of pre-analytical conditions, the interaction between the laboratory and the clinicians are indispensable for an optimal management of these pathologies.
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BACKGROUND: Multiple choroid plexus papillomas (CPPs) are rare. Usually, they correspond to villous hypertrophy or metastasis occurring during cerebrospinal dissemination. Multiple CPPs have rarely been reported as synchronous tumors. CASE REPORT: Three synchronous CPPs were resected in a 59-year-old female 6 years after their first imaging description. Pathology showed mucus-producing CPP in all 3, 1 of the 3 presenting some signs of atypia. No p53 or hSNF5/INI1 mutation, or signs of polyoma viruses infection were found. CONCLUSION: Although no clear cause for the multifocality was found, the simultaneous presence of the three tumors and their benign histology suggest that they were synchronous and not metastatic. The issue of differentiating synchronous CPPs from metastatic CPP is discussed.
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Neoplasias Primárias Múltiplas/patologia , Papiloma do Plexo Corióideo/patologia , Feminino , Humanos , Hidrocefalia de Pressão Normal/complicações , Hidrocefalia de Pressão Normal/cirurgia , Pessoa de Meia-Idade , Neoplasias Primárias Múltiplas/complicações , Papiloma do Plexo Corióideo/complicações , Derivação VentriculoperitonealRESUMO
Cerebral amyloid angiopathy-related inflammation (CAA-ri) is a rare autoimmune encephalopathy of aging caused by an autoantibody immune response against Aß protein deposited in the brain of older adults affected by cerebral amyloid angiopathy (CAA) and Alzheimer's disease pathology. Its most common clinical manifestations are (sub)acute-onset cognitive and behavioral abnormalities, focal deficits, seizures, and headaches. Brain magnetic resonance imaging shows characteristic extensive and confluent white matter hyperintensities and CAA features. The response to immunosuppressive treatment is generally good. Here, we report the case of a 62-year-old patient with CAA-ri confirmed on biopsy, who had previously repeatedly received chemotherapy for multiple cancers. We summarize his clinical data, neuroradiological features, and therapeutic response and comment on the potential mechanisms connecting multiple cancers and chemotherapies with CAA-ri.
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To improve the reliability of the quantitative scorings of the synovial biopsies, we evaluate whether diameter of arthroscopic forceps influences histological quality of synovial tissue and/or histological scores and we compare the intra- and inter-observer performances of the main histological scoring systems. Synovial biopsies were retrieved in the same part of the joint using 1, 2 and 4 mm diameters grasping forceps. After standard staining and immunohistochemistry with anti-CD68 antibody, slides were scored blindly by 2 independent experienced operators for tissue quality and with Krenn score, de Bois-Tak score and CD68 semi-quantitative score. Four samples did not pass quality control. No difference other than a higher number of vessels in the 4 mm versus 2 mm forceps (p = 0.01) was found among the 3 groups. CD68 score was significantly higher in the 2 versus 4 mm forceps (p = 0.009). So we concluded that only vessels quantification and CD68 semi-quantitative score seemed affected by the forceps size. The intra-reader agreement was variable across observers and features: 0.78 (0.66-0.87) for the Krenn scoring system, 0.89 (0.78-0.97) for the de Bois-Tak score and 0.93 (0.81-1.00) for the CD68 score. Interobserver reliabilities of Krenn score, de Bois-Tak score and CD68 scores were satisfactory: 0.95 (0.92-0.99) for Krenn, 0.98 (0.96-0.99) for de Bois-Tak and 0.80 (0.71-0.89) for CD68.
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Instrumentos Cirúrgicos , Membrana Sinovial , Biópsia , Contagem de Células , Humanos , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Membrana Sinovial/patologiaRESUMO
Hans Joachim Scherer (1906-1946) was a German pathologist who fled Germany to Belgium to work on glioma genesis, growth and progression. Despite being seldom cited, and due to the contributions discussed in this article, Hans Joachim Scherer, can be considered a founding father of contemporary neuropathology and glioma research. We discuss Scherer's achievements in glioma classification, glomerular structures of glioma, primary and secondary glioblastoma, glioma growth patterns, non-resectability of glioma, pseudopalisadic necrosis and the late occurrence of symptoms in glioma.
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Neoplasias Encefálicas/história , Glioma/história , Patologistas/história , II Guerra Mundial , Bélgica , Alemanha , História do Século XX , HumanosRESUMO
The integration of a viral genome into the host genome has a major impact on the trajectory of the infected cell. Integration location and variation within the associated viral genome can influence both clonal expansion and persistence of infected cells. Methods based on short-read sequencing can identify viral insertion sites, but the sequence of the viral genomes within remains unobserved. We develop PCIP-seq, a method that leverages long reads to identify insertion sites and sequence their associated viral genome. We apply the technique to exogenous retroviruses HTLV-1, BLV, and HIV-1, endogenous retroviruses, and human papillomavirus.
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Biologia Computacional/métodos , Genoma Viral , Genômica/métodos , Integração Viral , Animais , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo Único , Provírus/genética , Retroviridae/genéticaRESUMO
OBJECTIVES: Regulatory T cells (TR cells) play a crucial role in the regulation of intestinal inflammation. To examine the pathogenetic relevance of TR cells in inflammatory bowel disease (IBD), we evaluated their frequency in peripheral blood and inflamed and noninflamed mucosae of pediatric patients with IBD and age-matched controls without IBD; we also characterized the immune profile of the inflammatory infiltrate in the different phases of the disease. PATIENTS AND METHODS: Circulating TR cells were investigated on peripheral blood mononuclear cells by fluorescence-activated cell sorting analysis; mucosal TR cells and inflammatory cell populations were investigated by immunohistochemistry on bioptic specimens. FOXP3 messenger RNA expression levels were confirmed using real-time polymerase chain reaction. RESULTS: FOXP3+ TR cells were significantly increased in the intestinal lesions of patients with active IBD, and returned to normal levels in posttherapy remission phase. At variance, circulating TR cell frequency was elevated in patients with IBD independently of disease activity, as it persisted in the remission phase. A selective imbalance in the frequency of CD4+ T and natural killer cell subsets characterized the abundant inflammatory infiltrate of active intestinal lesions, and also persisted, at a lower level, in noninflamed mucosae of patients in the remission phase. CONCLUSIONS: TR cell frequency is differently regulated in mucosal tissues and at the systemic level during the distinct phases of pediatric IBD. The inactive stage of pediatric IBD is characterized by an incomplete normalization of the immune profile, independently of the clinical efficacy of the therapy. The pediatric, early-onset condition may represent a privileged observatory to dissect the immune-mediated pathogenetic mechanisms at the basis of the disease.
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Fatores de Transcrição Forkhead/imunologia , Doenças Inflamatórias Intestinais/imunologia , Mucosa Intestinal/imunologia , Intestinos/imunologia , Células Matadoras Naturais/metabolismo , Leucócitos Mononucleares/metabolismo , Linfócitos T Reguladores/metabolismo , Estudos de Casos e Controles , Criança , Fatores de Transcrição Forkhead/genética , Humanos , Doenças Inflamatórias Intestinais/sangue , Doenças Inflamatórias Intestinais/patologia , Mucosa Intestinal/patologia , Intestinos/patologia , Reação em Cadeia da Polimerase , RNA Mensageiro/metabolismo , Indução de RemissãoRESUMO
Mutations in LZTR1, already known to be causal in familial schwannomatosis type 2, have been recently involved in a small proportion of patients with autosomal dominant and autosomal recessive Noonan syndrome. LZTR1 is also a driver gene in non syndromal glioblastoma. We report a 26-year-old patient with typical Noonan syndrome, and the dominantly transmitted c.850Câ¯>â¯T (p.(Arg284Cys)) variant in LZTR1. An oligoastrocytoma was diagnosed in the patient at the age of 22 years; recurrence of the tumor occurred at age 26, as a ganglioblastoma. The patient had been transiently treated with growth hormone between ages 15 and 17. Considering the implication of LZTR1 in sporadic tumors of the nervous system, we hypothesize that gliomas are a possible complication of LZTR1-related Noonan syndrome. This report also supports a possible link between occurrence of a cerebral tumor in Noonan syndrome and a previous treatment with growth hormone.
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Astrocitoma/genética , Glioblastoma/genética , Síndrome de Noonan/genética , Fatores de Transcrição/genética , Adolescente , Adulto , Astrocitoma/complicações , Astrocitoma/diagnóstico , Astrocitoma/patologia , Feminino , Predisposição Genética para Doença , Glioblastoma/complicações , Glioblastoma/diagnóstico , Glioblastoma/patologia , Humanos , Masculino , Mutação , Síndrome de Noonan/complicações , Síndrome de Noonan/diagnóstico , Síndrome de Noonan/patologia , LinhagemRESUMO
It is now well recognized that osteoarthritis (OA) synovial membrane presents inflammatory components. The aim of this work is to provide evidence that similar inflammatory mechanisms exist in synovial membrane (n = 24) obtained from three pathologies presenting altogether an inflammatory gradient: OA, chronic pyrophosphate arthropathy (CPPA) and rheumatoid arthritis (RA). Synovial biopsies were first characterized by a histological score based on synovial hyperplasia and infiltration of lymphocytes, plasma cells, polymorphonuclear and macrophages. All biopsies were also analyzed by 2D-nano-UPLC-ESI-Q-Orbitrap for protein identification and quantification. Protein levels were correlated with the histological score. Histological score was in the range of 3 to 8 for OA, 5 to 13 for CPPA and 12 to 17 for RA. Of the 4,336 proteins identified by mass spectrometry, 51 proteins were selected for their strong correlation (p < 0.001) with the histological score of which 11 proteins (DNAJB11, CALR, ERP29, GANAB, HSP90B1, HSPA1A, HSPA5, HYOU1, LMAN1, PDIA4, and TXNDC5) were involved in the endoplasmic reticulum (ER) stress. Protein levels of S100A8 and S100A9 were significantly higher in RA compared to OA (for both) or to CPPA (for S100A8 only) and also significantly correlated with the histological score. Eighteen complement component proteins were identified, but only C1QB and C1QBP were weakly correlated with the histological score. This study highlights the inflammatory gradient existing between OA, CPPA and RA synovitis either at the protein level or at the histological level. Inflamed synovitis was characterized by the overexpression of ER stress proteins.
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Artrite Reumatoide/patologia , Condrocalcinose/patologia , Estresse do Retículo Endoplasmático , Mediadores da Inflamação/metabolismo , Osteoartrite/patologia , Proteínas/metabolismo , Sinovite/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Artrite Reumatoide/imunologia , Artrite Reumatoide/metabolismo , Biomarcadores/análise , Biomarcadores/metabolismo , Condrocalcinose/imunologia , Condrocalcinose/metabolismo , Difosfatos/metabolismo , Chaperona BiP do Retículo Endoplasmático , Feminino , Humanos , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Masculino , Pessoa de Meia-Idade , Osteoartrite/imunologia , Osteoartrite/metabolismo , Proteínas/análise , Proteoma/análise , Proteoma/metabolismo , Estudos Retrospectivos , Sinovite/imunologia , Sinovite/metabolismoAssuntos
Imageamento por Ressonância Magnética/métodos , Imagem Multimodal/métodos , Mieloma Múltiplo/diagnóstico , Plasmocitoma/diagnóstico , Tomografia por Emissão de Pósitrons/métodos , Neoplasias Cranianas/diagnóstico , Tomografia Computadorizada por Raios X/métodos , Diagnóstico Diferencial , Humanos , Masculino , Pessoa de Meia-Idade , CrânioRESUMO
Multiple primary central nervous system tumors are rarely seen in clinical practice and reported in the literature. The pathogenesis of multicentricity of primary tumors of the central nervous system still remains a debate, this pathology being found in almost two percent of reported tumor cases. Multifocal tumors are often described within the same hemisphere and supposed to be disseminated along the white matter tracts. On the opposite, multicentric tumors are found in the other hemisphere in subtentorial structures and are considered synchronous. We illustrate here the case of a young man admitted for symptoms of intracranial hypertension, diagnosed with multifocal and multicentric low-grade oligoastrocytoma with particular evolution and imagistic appearance.
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Astrocitoma/patologia , Adulto , Astrocitoma/diagnóstico por imagem , Evolução Fatal , Humanos , Imageamento por Ressonância Magnética , Masculino , Gradação de TumoresRESUMO
Glioblastoma (GBM) represents the most aggressive and common solid human brain tumor. We have recently demonstrated the importance of osteopontin (OPN) in the acquisition/maintenance of stemness characters and tumorigenicity of glioma initiating cells. Consultation of publicly available TCGA database indicated that high OPN expression correlated with poor survival in GBM patients. In this study, we explored the role of OPN in GBM radioresistance using an OPN-depletion strategy in U87-MG, U87-MG vIII and U251-MG human GBM cell lines. Clonogenic experiments showed that OPN-depleted GBM cells were sensitized to irradiation. In comet assays, these cells displayed higher amounts of unrepaired DNA fragments post-irradiation when compared to control. We next evaluated the phosphorylation of key markers of DNA double-strand break repair pathway. Activating phosphorylation of H2AX, ATM and 53BP1 was significantly decreased in OPN-deficient cells. The addition of recombinant OPN prior to irradiation rescued phospho-H2AX foci formation thus establishing a new link between DNA repair and OPN expression in GBM cells. Finally, OPN knockdown improved mice survival and induced a significant reduction of heterotopic human GBM xenograft when combined with radiotherapy. This study reveals a new function of OPN in DNA damage repair process post-irradiation thus further confirming its major role in GBM aggressive disease.