Functional and transcriptional induction of aquaporin-1 gene by hypoxia; analysis of promoter and role of Hif-1α.

Aquaporin-1 (AQP1) is a water channel that is highly expressed in tissues with rapid O(2) transport. It has been reported that this protein contributes to gas permeation (CO(2), NO and O(2)) through the plasma membrane. We show that hypoxia increases Aqp1 mRNA and protein levels in tissues, namely mouse brain and lung, and in cultured cells, the 9L glioma cell line. Stopped-flow light-scattering experiments confirmed an increase in the water permeability of 9L cells exposed to hypoxia, supporting the view that hypoxic Aqp1 up-regulation has a functional role. To investigate the molecular mechanisms underlying this regulatory process, transcriptional regulation was studied by transient transfections of mouse endothelial cells with a 1297 bp 5' proximal Aqp1 promoter-luciferase construct. Incubation in hypoxia produced a dose- and time-dependent induction of luciferase activity that was also obtained after treatments with hypoxia mimetics (DMOG and CoCl(2)) and by overexpressing stabilized mutated forms of HIF-1α. Single mutations or full deletions of the three putative HIF binding domains present in the Aqp1 promoter partially reduced its responsiveness to hypoxia, and transfection with Hif-1α siRNA decreased the in vitro hypoxia induction of Aqp1 mRNA and protein levels. Our results indicate that HIF-1α participates in the hypoxic induction of AQP1. However, we also demonstrate that the activation of Aqp1 promoter by hypoxia is complex and multifactorial and suggest that besides HIF-1α other transcription factors might contribute to this regulatory process. These data provide a conceptual framework to support future research on the involvement of AQP1 in a range of pathophysiological conditions, including edema, tumor growth, and respiratory diseases.

Differential prefrontal-like deficit in children after cerebellar astrocytoma and medulloblastoma tumor

BACKGROUND This study was realized thanks to the collaboration of children and adolescents who had been resected from cerebellar tumors. The medulloblastoma group (CE+, n = 7) in addition to surgery received radiation and chemotherapy. The astrocytoma group (CE, n = 13) did not receive additional treatments. Each clinical group was compared in their executive functioning with a paired control group (n = 12). The performances of the clinical groups with respect to controls were compared considering the tumor's localization (vermis or hemisphere) and the affectation (or not) of the dentate nucleus. Executive variables were correlated with the age at surgery, the time between surgery-evaluation and the resected volume. METHODS The executive functioning was assessed by means of WCST, Complex Rey Figure, Controlled Oral Word Association Test (letter and animal categories), Digits span (WISC-R verbal scale) and Stroop test. These tests are very sensitive to dorsolateral PFC and/or to medial frontal cortex functions. The scores for the non-verbal Raven IQ were also obtained. Direct scores were corrected by age and transformed in standard scores using normative data. The neuropsychological evaluation was made at 3.25 (SD = 2.74) years from surgery in CE group and at 6.47 (SD = 2.77) in CE+ group. RESULTS The Medulloblastoma group showed severe executive deficit (

Neuropathologie et pathologie moléculaire des gliomes [Neuropathology and molecular pathology of gliomas]

Gliomas are the most frequent primary brain tumours. The WHO classification is essentially based on histological and immunohistochemical criteria. More recently multiple cytogenetic and molecular alterations associated with initiation and progression have been shown and the genetic profiles of tumour entities have been incorporated in the WHO classifiacation. Molecular testing of the MGMT promotor methylation in glioblastoma, predictive for the response to combined radio-/chimiothérapie, and the LOH 1p/19q in oligodendroglial tumours, as prognostic factor supplements the histopathological diagnosis. In the near futur array-based profiling techniques will contribute to a refinement of glioma classification and identify targets for more individualized glioma therapies.

Effectiveness of the bevacizumab-irinotecan regimen in the treatment of recurrent glioblastoma multiforme: Comparison with other second-line treatments without this regimen.

A retrospective cohort study was conducted to analyse the effectiveness of bevacizumab and irinotecan (BVZ/CPT-11) as a second-line treatment in patients with primary glioblastoma multiforme (GBM) in comparison with a control group that were not administered BVZ/CPT-11 at the first recurrence. The difference in overall survival (OS) between the two groups was used as a predictor of effectiveness. OS was calculated according to prognostic factors and gender. A total of 28 and 32 patients were enrolled in the BVZ/CPT-11 cohort and control group, respectively. The median OS was 17.94 months (95% CI, 14.91-20.96) in the BVZ/CPT-11 treatment cohort and 10.97 months (95% CI, 7.65-14.30) in the control cohort. The results obtained on the effectiveness of BVZ/CPT-11 treatment in patients with primary GBM are consistent with data from previous studies. No significant differences were identified in OS based on prognostic factors; therefore, the latter cannot be used to select patients who would incur the greatest benefits from BVZ/CPT-11 treatment.

The prevalence of human cytomegalovirus DNA in gliomas of Brazilian patients

Members of the Herpesviridae family have been implicated in a number of tumours in humans. At least 75% of the human population has had contact with cytomegalovirus (HCMV). In this work, we screened 75 Brazilian glioma biopsies for the presence of HCMV DNA sequences. HCMV DNA was detected in 36% (27/75) of the biopsies. It is possible that HCMV could be a co-factor in the evolution of brain tumours.

Salvage radiosurgery for selected patients with recurrent malignant gliomas.

Purpose. To analyse the survival after salvage radiosurgery and to identify prognostic factors. Methods. We retrospectively reviewed 87 consecutive patients, with recurrent high-grade glioma, that underwent stereotactic radiosurgery between 1997 and 2010. We evaluated the survival after initial diagnosis and after reirradiation. The prognostic factors were analysed by bivariate and multivariate Cox regression model. Results. The median age was 48 years old. The primary histology included anaplastic astrocytoma (47%) and glioblastoma (53%). A margin dose of 18 Gy was administered in the majority of cases (74%). The median survival after initial diagnosis was 21 months (39 months for anaplastic astrocytoma and 18.5 months for glioblastoma) and after reirradiation it was 10 months (17 months for anaplastic astrocytoma and 7.5 months for glioblastoma). In the bivariate analyses, the prognostic factors significantly associated with survival after reirradiation were age, tumour and treatment volume at recurrence, recursive partitioning analyses classification, Karnofsky performance score, histology, and margin to the planning target volume. Only the last four showed significant association in the multivariate analyses. Conclusion. stereotactic radiosurgery is a safe and may be an effective treatment option for selected patients diagnosed with recurrent high-grade glioma. The identified prognostic factors could help individualise the treatment.

Estudio prospectivo, longitudinal y observacional, sobre el grado de resección quirúrgica y la calidad de vida en pacientes con gliomas. Resultados de un estudio piloto.

En este estudio prospectivo observacional se evaluaron 60 pacientes diagnosticados de glioma cerebral y sometidos a algún tipo de intervención quirúrgica como parte de su tratamiento. En ellos se analizaron las variables demográficas, clínicas, la localización de las lesiones, el volumen tumoral basal, así como, escalas de calidad de vida y el efecto del grado de resección tumoral (biopsia, resección parcial y resección total/subtotal) sobre las mismas. Los hallazgos de nuestro estudio confirmaron el beneficio de las resecciones tumorales amplias en la calidad de vida de los pacientes. Se discuten las dificultades técnicas de este tipo de estudio y su importancia de la incorporación de estas escalas en futuros estudios neuro-oncológicos.

A combined molecular clinical predictor of survival validated with the rtog-0525 cohort

For glioblastoma (GBM), survival classification has primarily relied on clinical criteria, exemplified by the Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA). We sought to improve tumor classification by combining tumor biomarkers with the clinical RPA data. To accomplish this, we first developed 4 molecular biomarkers derived from gene expression profiling, a glioma CpG island methylator phenotype, a novel MGMT promoter methylation assay, and IDH1 mutations. A molecular predictor (MP) model was created with these 4 biomarkers on a training set of 220 retrospectively collected archival GBMtumors. ThisMPwas further combined with RPA classification to develop a molecular-clinical predictor (MCP). The median survivals for the combined, 4-class MCP were 65 months, 31 months, 13 months, and 9 months, which was significantly improved when compared with the RPA alone. The MCP was then applied to 725 samples from the RTOG-0525 cohort, showing median survival for each risk group of NR, 26 months, 16 months, and 11 months. The MCP was significantly improved over the RPA at outcome prediction in the RTOG 0525 cohort with a 33%increase in explained variation with respect to survival, validating the result obtained in the training set. To illustrate the benefit of the MCP for patient stratification, we examined progression-free survival (PFS) for patients receiving standard-dose temozolomide (SD-TMZ) vs. dose-dense TMZ (DD-TMZ) in RPA and MCP risk groups. A significant difference between DD-TMZ and SD-TMZ was observed in the poorest surviving MCP risk group with a median PFS of 6 months vs. 3 months (p ¼ 0.048, log-rank test). This difference was not seen using the RPA classification alone. In summary, we have developed a combined molecular-clinical predictor that appears to improve outcome prediction when compared with clinical variables alone. This MCP may serve to better identify patients requiring intensive treatments beyond the standard of care.

Microtubule-associated protein-2 immunoreactivity: a useful tool in the differential diagnosis of low-grade neuroepithelial tumors.

Complex and variable morphological phenotypes pose a major challenge to the histopathological classification of neuroepithelial tumors. This applies in particular for low-grade gliomas and glio-neuronal tumors. Recently, we and others have identified microtubule-associated protein-2 (MAP2) as an immunohistochemical marker expressed in the majority of glial tumors. Characteristic cell morphologies can be recognized by MAP2 immunoreactivity in different glioma entities, i.e., process sparse oligodendroglial versus densely ramified astrocytic elements. Here, we describe MAP2-immunoreactivity patterns in a large series of various neuroepithelial tumors and related neoplasms (n = 960). Immunohistochemical analysis led to the following conclusions: (1) specific pattern of MAP2-positive tumor cells can be identified in 95% of glial neoplasms; (2) ependymal tumors do not express MAP2 in their rosette-forming cell component; (3) tumors of the pineal gland as well as malignant embryonic tumors are also characterized by abundant MAP2 immunoreactivity; (4) virtually no MAP2 expression can be observed in the neoplastic glial component of glio-neuronal tumors, i.e. gangliogliomas; (5) malignant glial tumor variants (WHO grade III or IV) exhibit different and less specific MAP2 staining patterns compared to their benign counterparts (WHO grade I or II); (6) with the exception of melanomas and small cell lung cancers, MAP2 expression is very rare in metastatic and non-neuroepithelial tumors; (7) glial MAP2 expression was not detected in 56 non-neoplastic lesions. These data point towards MAP2 as valuable diagnostic tool for pattern recognition and differential diagnosis of low-grade neuroepithelial tumors.

Prolonged survival for patients with newly diagnosed, inoperable glioblastoma with 3-times daily ultrafractionated radiation therapy.

Ultrafractionation of radiation therapy is a novel regimen consisting of irradiating tumors several times daily, delivering low doses (<0.75 Gy) at which hyperradiosensitivity occurs. We recently demonstrated the high efficiency of ultrafractionated radiotherapy (RT) on glioma xenografts and report here on a phase II clinical trial to determine the safety, tolerability, and efficacy of an ultrafractionation regimen in patients with newly and inoperable glioblastoma (GBM). Thirty-one patients with histologically proven, newly diagnosed, and unresectable supratentorial GBM (WHO grade IV) were enrolled. Three daily doses of 0.75 Gy were delivered at least 4 hours apart, 5 days per week over 6-7 consecutive weeks (90 fractions for a total of 67.5 Gy). Conformal irradiation included the tumor bulk with a margin of 2.5 cm. The primary end points were safety, toxicity, and tolerability, and the secondary end points were overall survival (OS) and progression-free survival (PFS). Multivariate analysis was used to compare the OS and PFS with the EORTC-NCIC trial 26981-22981/CE.3 of RT alone vs radiation therapy and temozolomide (TMZ). The ultrafractionation radiation regimen was safe and well tolerated. No acute Grade III and/or IV CNS toxicity was observed. Median PFS and OS from initial diagnosis were 5.1 and 9.5 months, respectively. When comparing with the EORTC/NCIC trial, in both PFS and OS multivariate analysis, ultrafractionation showed superiority over RT alone, but not over RT and TMZ. The ultrafractionation regimen is safe and may prolong the survival of patients with GBM. Further investigation is warranted and a trial associating ultra-fractionation and TMZ is ongoing.

CD44 attenuates activation of the hippo signaling pathway and is a prime therapeutic target for glioblastoma.

Glioblastoma multiforme (GBM) is the most aggressive brain tumor that, by virtue of its resistance to chemotherapy and radiotherapy, is currently incurable. Identification of molecules whose targeting may eliminate GBM cells and/or sensitize glioblastoma cells to cytotoxic drugs is therefore urgently needed. CD44 is a major cell surface hyaluronan receptor and cancer stem cell marker that has been implicated in the progression of a variety of cancer types. However, the major downstream signaling pathways that mediate its protumor effects and the role of CD44 in the progression and chemoresponse of GBM have not been established. Here we show that CD44 is upregulated in GBM and that its depletion blocks GBM growth and sensitizes GBM cells to cytotoxic drugs in vivo. Consistent with this observation, CD44 antagonists potently inhibit glioma growth in preclinical mouse models. We provide the first evidence that CD44 functions upstream of the mammalian Hippo signaling pathway and that CD44 promotes tumor cell resistance to reactive oxygen species-induced and cytotoxic agent-induced stress by attenuating activation of the Hippo signaling pathway. Together, our results identify CD44 as a prime therapeutic target for GBM, establish potent antiglioma efficacy of CD44 antagonists, uncover a novel CD44 signaling pathway, and provide a first mechanistic explanation as to how upregulation of CD44 may constitute a key event in leading to cancer cell resistance to stresses of different origins. Finally, our results provide a rational explanation for the observation that functional inhibition of CD44 augments the efficacy of chemotherapy and radiation therapy.

Identification et caractérisation de gènes suppresseurs de tumeurs dans le glioblastome

Introduction: Glioblastoma (WHO Grade IV glioma) is the most frequent and most¦malignant primary tumor of the brain. With a mean survival of 15 months despite¦multidisciplinary management combining surgery, chemo- and radiotherapy, the prognosis¦is poor. Different studies measured a down-regulation of Wnt Inhibitory Factor 1 (WIF1)¦expression in a majority of gliobastoma due to genetic and epigenetic regulation. Recently,¦a focus on chromosome 12 identified WIF1 as a potential tumor suppressor gene. In¦previous results, transfected glioblastoma cells with ectopic expression of WIF1 had a¦decreased growth rate and adopted a senescence-like phenotype. In this report, we first¦investigated the effect of WIF1 re-expression in glioblastoma cell lines to see if Wnt¦inhibition by WIF1 can lead to senescence. To look further, we assessed p21 and c-Myc¦expression. p21 has a key role in senescence onset and is directly inhibited by c-Myc,¦itself a target of Wnt-pathway. We thus looked if a variation of expression of these genes is¦triggered by WIF1 activity. Finally, as autophagy is thought to play a role in senescence¦onset, we analyzed the expression of different autophagy genes. We therefore looked for¦an association between autophagy activity and senescent phenotype in WIF1-¦overexpressing cell lines.¦Methods: WIF1-overexpressing clones were selected after transfection of stable¦glioblastoma cell lines. Analysis were made through quantitative Polymerase Chain¦Reaction (qPCR), Fluorescence-activated Cell Sorting (FACS) and histochemistry.¦IGFBP7 and ALDH1A3 have been selected to reflect senescence. ATG5, ATG7 and ULK3¦have been selected to reflect autophagy activity.¦Results: Using FACS analysis, we found a higher percentage of large cells with increased¦granularity amongst WIF1-overexpressing cell lines, which are characteristics of¦senescence. In addition, histochemistry showed a higher percentage of multi-nucleated,¦beta-galactosidase positive cells in the same cell lines. An increased expression of genes¦associated with senescence was found as well. All characteristics were correlated with¦levels of WIF1 expression. We did not find any association between p21 and WIF1¦expression. No correlation between WIF1 and c-Myc expression was noticed either. In one¦of the two cell lines analyzed, the expression of autophagy genes showed some¦correlation with expression of WIF1 and expression of genes associated with senescence.¦Discussion: After investigations and characterizations on multiple levels, we have¦evidence for a senescence phenotype upon WIF1-overexpressing cell lines. This gives a¦role to Wnt pathway in the tumorigenicity of glioblastoma. Further experiments are¦required to investigate how Wnt inhibition leads to senescence. The role of autophagy in¦our senescent cells is here still unclear. Some correlations can be found, letting us think¦that there is indeed some involvement of autophagy. However, it is yet to soon to explain¦this relationship. Further experiments are required again to confirm the preliminary results¦and analyze the variations of autophagy activity within time.

In vivo localisation of radiolabelled monoclonal antibody in human gliomas.

F(ab')2-fragments of the anti-melanoma monoclonal antibody MeI-14 were labelled with 123I for external scanning and with 125I for tissue measurement of radioactivity and injected intravenously into patients scheduled for surgical resection of a glioma. The paired-label study was performed by injecting simultaneously 131I-labelled control (F(ab')2-fragments. The patients were scanned by computerised tomoscintigraphy. After surgery, the activities of 125I and 131I were counted in tumour and normal tissues. The results indicate that there was a low but definite uptake of the antibody in the tumour due to its specificity. The external detection was difficult because of accumulation of antibody fragments in the skull.