EGFRvIII deletion mutations in pediatric high-grade glioma and response to targeted therapy in pediatric glioma cell lines

Purpose: The epidermal growth factor receptor (EGFR) is amplified and overexpressed in adult glioblastoma, with response to targeted inhibition dependent on the underlying biology of the disease. EGFR has thus far been considered to play a less important role in pediatric glioma, although extensive data are lacking. We have sought to clarify the role of EGFR in pediatric high-grade glioma (HGG). Experimental Design: We retrospectively studied a total of 90 archival pediatric HGG specimens for EGFR protein overexpression, gene amplification, and mutation and assessed the in vitro sensitivity of pediatric glioma cell line models to the small-molecule EGFR inhibitor erlotinib. Results: Amplification was detected in 11% of cases, with corresponding overexpression of the receptor. No kinase or extracellular domain mutations were observed; however, 6 of 35 (17%) cases harbored the EGFRvIII deletion, including two anaplastic oligodendrogliomas and a gliosarcoma overexpressing EGFRvIII in the absence of gene amplification and coexpressing platelet-derived growth factor receptor α. Pediatric glioblastoma cells transduced with wild-type or deletion mutant EGFRvIII were not rendered more sensitive to erlotinib despite expressing wild-type PTEN. Phosphorylated receptor tyrosine kinase profiling showed a specific activation of platelet-derived growth factor receptor α/β in EGFRvIII-transduced pediatric glioblastoma cells, and targeted coinhibition with erlotinib and imatinib leads to enhanced efficacy in this model. Conclusions: These data identify an elevated frequency of EGFR gene amplification and EGFRvIII mutation in pediatric HGG than previously recognized and show the likely necessity of targeting multiple genetic alterations in the tumors of these children.Cancer Research UK grants C1178/A10294, C309/A2187, and C309/A8274; Oak Foundation (L. Marshall); La Fondation de France (N. Gaspar); and Breakthrough Breast Cancer (J.S. Reis-Filho). We acknowledge NHS funding to the National Institute for Health Research Biomedical Research Centre

Mus81-mediated DNA cleavage resolves replication forks stalled by topoisomerase I–DNA complexes

Replication forks stalled by excess DNA supercoiling can be resolved by DNA cleavage by the Mus81 endonuclease

Poly(ADP-ribose) polymerase and XPF–ERCC1 participate in distinct pathways for the repair of topoisomerase I-induced DNA damage in mammalian cells

Poly(ADP-Ribose) (PAR) polymerase (PARP) inhibitors represent a promising class of novel anticancer agents. The present study explores the molecular rationale for combining veliparib (ABT-888) with camptothecin (CPT) and its clinical derivatives, topotecan and irinotecan. ABT-888 inhibited PAR induction by CPT and increased CPT-induced cell killing and histone γH2AX. Increased DNA breaks by ABT-888 were not associated with a corresponding increase of topoisomerase I cleavage complexes and were further increased by inactivation of tyrosyl-DNA phosphodiesterase 1. SiRNA knockdown for the endonuclease XPF–ERCC1 reduced the ABT-888-induced γH2AX response in non-replicating and replicating cells but enhanced the antiproliferative effect of ABT-888 in CPT-treated cells. Our findings indicate the involvement of XPF–ERCC1 in inducing γH2AX response and repairing topoisomerase I-induced DNA damage as an alternative pathway from PARP and tyrosyl-DNA phosphodiesterase 1

Génomique de la résistance in vivo aux inhibiteurs de topoisomerase I dans le neuroblasrome (identification et analyse du rôle de la voie ALK)

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocSudocFranceF

Réduire la pollution azotée : les choix préalables d'une politique publique

National audienceCet article analyse les différents arbitrages qui devront être effectués afin de définir une politique publique de réduction de la pollution nitrique d'origine agricole. Dans cette optique, il répond à quatre grandes questions qui constituent les parties de l'exposé : (i) quel est l'impact sur la qualité de l'eau des pratiques agricoles actuelles ? Quelle est l'origine exacte de la pollution et comment la mesurer ? ; (ii) quelle est l'efficacité environnementale et quel est le coût des solutions techniques existantes pour réduire cette pollution ? ; (iii) quels sont les choix majeurs à effectuer pour définir une politique publique de réduction de ces pollutions, en termes d'objectif environnemental, de population-cible et de niveau de régulation ? ; (iv) quelle est la compatibilité de cette politique environnementale avec la politique agricole commune (PAC), en particulier les critères d'attribution des primes PAC ? Les réponses à ces questions s'appuient sur une recherche réalisée, en collaboration interdisciplinaire très étroite avec des agronomes et des hydrologues, sur le site de la plaine de Bièvre-Liers (région de la Côte-Saint-André-Isère)

Réduire la pollution azotée : les choix préalables d'une politique publique

National audienceCet article analyse les différents arbitrages qui devront être effectués afin de définir une politique publique de réduction de la pollution nitrique d'origine agricole. Dans cette optique, il répond à quatre grandes questions qui constituent les parties de l'exposé : (i) quel est l'impact sur la qualité de l'eau des pratiques agricoles actuelles ? Quelle est l'origine exacte de la pollution et comment la mesurer ? ; (ii) quelle est l'efficacité environnementale et quel est le coût des solutions techniques existantes pour réduire cette pollution ? ; (iii) quels sont les choix majeurs à effectuer pour définir une politique publique de réduction de ces pollutions, en termes d'objectif environnemental, de population-cible et de niveau de régulation ? ; (iv) quelle est la compatibilité de cette politique environnementale avec la politique agricole commune (PAC), en particulier les critères d'attribution des primes PAC ? Les réponses à ces questions s'appuient sur une recherche réalisée, en collaboration interdisciplinaire très étroite avec des agronomes et des hydrologues, sur le site de la plaine de Bièvre-Liers (région de la Côte-Saint-André-Isère)

Terbium-based time-gated Förster resonance energy transfer imaging for evaluating protein–protein interactions on cell membranes

International audienc

High level of apoptosis and low AKT activation in mass screening as opposed to standard neuroblastoma

AIMS: Neuroblastoma is a paediatric solid tumour with a poor outcome except in children <1 year old. Based on catecholamine urinary excretion, mass screening (MS) programmes have been organized but failed to decrease the mortality of this tumour. To test the hypotheses of a spontaneous maturation/differentiation or regression, the levels of poly (ADP-ribose) polymerase (PARP)-1, an early apoptosis marker, of PhosphoAKT, a major apoptosis inhibitor, and of maturation/differentiation were compared in standard and in MS neuroblastomas. METHODS AND RESULTS: We performed a case-control study of 55 primary tumours and 21 metastases of MS neuroblastomas. Matched controls were standard unscreened neuroblastomas and were paired according to age, stage, and MYCN amplification. The tumours were included in tissue microarrays. Immunohistochemical staining was performed using antibodies against, AKT, phosphoAKT, TRKB and PARP-1. The expression of PARP-1 and that of phosphoAKT were significantly higher in standard than in MS neuroblastomas independently of age and stage of the tumour. PhosphoAKT and PARP-1 expression was significantly correlated in both tumours. CONCLUSIONS: These data suggest that the better prognosis of patients with MS neuroblastomas compared with classical neuroblastomas was secondary to spontaneous tumour regression mediated by higher levels of apoptosis associated with low activation of AKT

Int. J. Oncol.

Irinotecan is a major anticancer agent specifically targeting DNA topoisomerase I. Its cytotoxicity is mediated via a two-step process involving accumulation of reversible DNA‑topoisomerase I complexes associated with transient DNA single-strand breaks which subsequently are converted into permanent DNA double-strand breaks by the replication fork during S phase. Irinotecan may be selectively active for treatment of colorectal cancers that show microsatellite instability (MSI) due to deficiencies in mismatch repair enzymes, compared to tumors that are microsatellite stable but show chromosome instability (CIN). Although the clinical activity of irinotecan is principally limited by acquired drug resistance, surprisingly little is known about the influence of prolonged irinotecan exposure on the cell cycle dynamics. We have developed two colon cancer cell lines resistant to SN-38, the active metabolite of irinotecan, one derived from HT-29 (CIN), the other from HCT-116 (MSI). We here show that besides classical resistance mechanisms, SN-38 resistance is accompanied by an increased generation doubling time, a decreased S phase fraction and an increased G2 fraction in vitro as in tumor xenografts for both CIN and MSI models. As a consequence, SN-38-resistant cells and tumors show cross-resistance to the S-phase selective agent 5-fluorouracil. The resistance is accompanied by increased basal levels of γ-H2AX and phospho-Chk2 without notable changes in the levels of phospho-Chk1. Taken together, our results show that prolonged irinotecan exposure is accompanied by stable modifications of cell cycle dynamics which could have profound impact on tumor sensitivity to a wide range of antitumor agents and may influence tumor progression in patients

Mutation-Independent Activation of the Anaplastic Lymphoma Kinase in Neuroblastoma

International audienc