Heidi Espedal

Bevacizumab treatment induces metabolic adaptation toward anaerobic metabolism in glioblastomas

Anti-angiogenic therapy in glioblastoma (GBM) has unfortunately not led to the anticipated improvement in patient prognosis. We here describe how human GBM adapts to bevacizumab treatment at the metabolic level. By performing 13C6-glucose metabolic flux analysis, we show for the first time that the tumors undergo metabolic re-programming toward anaerobic metabolism, thereby uncoupling glycolysis from oxidative phosphorylation. Following treatment, an increased influx of 13C6-glucose was observed into the tumors, concomitant to increased lactate levels and a reduction of metabolites associated with the tricarboxylic acid cycle. This was confirmed by increased expression of glycolytic enzymes including pyruvate dehydrogenase kinase in the treated tumors. Interestingly, l-glutamine levels were also reduced. These results were further confirmed by the assessment of in vivo metabolic data obtained by magnetic resonance spectroscopy and positron emission tomography. Moreover, bevacizumab led to a depletion in glutathione levels indicating that the treatment caused oxidative stress in the tumors. Confirming the metabolic flux results, immunohistochemical analysis showed an up-regulation of lactate dehydrogenase in the bevacizumab-treated tumor core as well as in single tumor cells infiltrating the brain, which may explain the increased invasion observed after bevacizumab treatment. These observations were further validated in a panel of eight human GBM patients in which paired biopsy samples were obtained before and after bevacizumab treatment. Importantly, we show that the GBM adaptation to bevacizumab therapy is not mediated by clonal selection mechanisms, but represents an adaptive response to therapy.

Satellite detection of natural films on the ocean surface

Natural films on the ocean surface influence air-sea fluxes of momentum, heat and gas. It is therefore essential to be able to map the geographical extent and variability of such films to determine the resulting impact on the earths climate system. Satellite based Synthetic Aperture Radar (SAR) may prove very useful, and perhaps the only way, to quantify global scale film distribution. In order to investigate the composition of natural film and its effect on radar return, in situ samples of the surface microlayer were for the first time taken simultaneously with ERS-1 SAR coverage of the sea. Our results show that the film was enriched in organic composition and that the concentration of fatty acids was generally one order of magnitude higher inside than outside natural film areas, resulting in a 6–17 dB decrease in radar backscatter.

Satellite earth observation in operational oceanography

The role and contribution of satellite data in operational oceanography is reviewed, with emphasis on northern European seas. The possibility to observe various ocean parameters and processes by existing satellite sensors, such as optical instruments, infrared radiometers, passive microwave radiometers, and active microwave systems (altimeter, scatterometer, SAR) is discussed. The basic parameters are: sea-surface temperature observed by infrared radiometers, ocean colour by spectrometers, sea-surface elevation by altimeters, and surface roughness by active and passive microwave systems, which can be used to derive surface wind and waves. A number of ocean processes can be derived from synoptic mapping of the basic parameters of larger sea areas, such as current patterns, fronts, eddies, water mass distribution, and various water quality parameters (chlorophyll, surface slicks, suspended sediments). The suitability of existing satellite data to fulfil the operational requirements for temporal and spatial coverage, data delivery in near-real-time, and long-term access to data is discussed in light of the fact that optical/infrared data in northern Europe are severely hampered by frequent cloud cover, while microwave techniques can provide useful data independent of weather and light conditions. Finally, the use of data assimilation in oceanographic models is briefly summarised, indicating that this technique is under development and will soon be adopted in operational oceanography.

Intercellular transfer of transferrin receptor by a contact-, Rab8-dependent mechanism involving tunneling nanotubes

Intercellular communication between cancer cells, especially between cancer and stromal cells, plays an important role in disease progression. We examined the intercellular transfer of organelles and proteins in vitro and in vivo and the role of tunneling nanotubes (TNTs) in this process. TNTs are membrane bridges that facilitate intercellular transfer of organelles of unclear origin. Using 3‐dimensional quantitative and qualitative confocal microscopy, we showed that TNTs contain green fluorescent protein (GFP)‐early endosome antigen (EEA) 1, GFP Rab5, GFP Rab11, GFP Rab8, transferrin (Tf), and Tf receptor (Tf‐R) fused to mCherry (Tf‐RmCherry). Tf‐RmCherry was transferred between cancer cells by a contact‐dependent but secretion‐independent mechanism. Live cell imaging showed TNT formation preceding the transfer of Tf‐RmCherry and involving the function of the small guanosine triphosphatase (GTPase) Rab8, which colocalized with Tf‐RmCherry in the TNTs and was cotransferred to acceptor cells. Tf‐RmCherry was transferred from cancer cells to fibroblasts, a noteworthy finding that suggests that this process occurs between tumor and stromal cells in vivo. We strengthened this hypothesis in a xenograft model of breast cancer using enhanced (e)GFP‐expressing mice. Tf‐RmCherry transferred from tumor to stromal cells and this process correlated with an increased opposite transfer of eGFP from stromal to tumor cells, together pointing toward complex intercellular communication at the tumor site.—Burtey, A., Wagner, M., Hodneland, E., Skaftnesmo, K. O., Schoelermann, J., Mondragon, I. R., Espedal, H., Golebiewska, A., Niclou, S. P., Bjerkvig, R., Kögel, T., Gerdes, H.‐H. Intercellular transfer of transferrin receptor by a contact‐, Rab8‐dependent mechanism involving tunneling nanotubes. FASEB J. 29, 4695‐4712 (2015). www.fasebj.org

Transmembrane protein CD9 is glioblastoma biomarker, relevant for maintenance of glioblastoma stem cells.

The cancer stem cell model suggests that glioblastomas contain a subpopulation of stem-like tumor cells that reproduce themselves to sustain tumor growth. Targeting these cells thus represents a novel treatment strategy and therefore more specific markers that characterize glioblastoma stem cells need to be identified. In the present study, we performed transcriptomic analysis of glioblastoma tissues compared to normal brain tissues revealing sensible up-regulation of CD9 gene. CD9 encodes the transmembrane protein tetraspanin which is involved in tumor cell invasion, apoptosis and resistance to chemotherapy. Using the public REMBRANDT database for brain tumors, we confirmed the prognostic value of CD9, whereby a more than two fold up-regulation correlates with shorter patient survival. We validated CD9 gene and protein expression showing selective up-regulation in glioblastoma stem cells isolated from primary biopsies and in primary organotypic glioblastoma spheroids as well as in U87-MG and U373 glioblastoma cell lines. In contrast, no or low CD9 gene expression was observed in normal human astrocytes, normal brain tissue and neural stem cells. CD9 silencing in three CD133+ glioblastoma cell lines (NCH644, NCH421k and NCH660h) led to decreased cell proliferation, survival, invasion, and self-renewal ability, and altered expression of the stem-cell markers CD133, nestin and SOX2. Moreover, CD9-silenced glioblastoma stem cells showed altered activation patterns of the Akt, MapK and Stat3 signaling transducers. Orthotopic xenotransplantation of CD9-silenced glioblastoma stem cells into nude rats promoted prolonged survival. Therefore, CD9 should be further evaluated as a target for glioblastoma treatment.

Natural films in coastal waters

Mesoscale ocean phenomena such as eddies are often depicted by characteristic film patterns. Surface slicks dampen out the centimetre-scale surface waves, causing a low radar backscatter signal. Similar backscatter values are found for e.g. oil spill and grease ice. In order to investigate the composition of the natural films or the so called surface microlayer, samples of the sea surface were for the first time taken simultaneously with ERS-1 SAR coverage of the relevant area. Both slick and nonslick sites were included in the experiment. The samples were analyzed for differences in several chemical parameters to verify whether the dark patches in the SAR image could be related to increased biological activity, i.e. to natural film. A chemical difference between slicked and non-slicked areas corresponding to respectively dark and brighter areas in the ERS-1 SAR image was identified.

Bevacizumab treatment for human glioblastoma. Can it induce cognitive impairment

Recent results from 2 double-blind, placebo-controlled phase III trials (RTOG 0825) and (AVAglio) for first-line treatment of glioblastoma patients with the VEGF antibody bevacizumab, showed similar results, related to overall and progression-free survival. The RTOG 0825 trial indicated, opposed to the AVAglio trial, that patients treated with bevacizumab showed a decline in global neurocognitive function compared to untreated patients, -a decline that was most obvious after prolonged treatment. At present, there is a considerably controversy related to these observations. In the present work we point at the possibility that bevacizumab treatment of the normal brain can reduce synaptic plasticity in the hippocampus. We believe that such a phenomenon may partly explain the reduced cognitive function observed in patients in the RTOG 0825 trial. Since the same effects were not clearly defined in the AVAglio trial, further studies on putative neurocognitive effects after bevacizumab treatment are warranted.

COAST WATCH: Using SAR imagery in an operational system for monitoring coastal currents, wind, surfactants and oil spills

Publisher Summary This chapter discusses the use of synthetic aperture radar (SAR) imagery in an operational system for monitoring coastal currents, wind, surfactants, and oil spills. The examples given of SAR products from COAST WATCH are defined in an ocean and coastal monitoring project. The main objectives were to involve users and to demonstrate SAR products for an integrated monitoring service. A survey of potential users of the monitoring service is carried out and a demonstration case study is proposed, which initially included The Fedje Ship Traffic Control Centre in western Norway as end user. After an iteration process with feedback from the user, the system is operationally tested for a few months, followed by a cost-benefit analysis of the service. The suggested organization of the service for a demonstration project is shown in the chapter. A discussion of the marine monitoring and forecasting system is also presented.

Marine SAR Analysis and Interpretation System - MARSAIS

In a marine coastal ocean monitoring and prediction system, multisensor in-situ and remote sensing observations (of coastal currents, fronts, eddies, upwelling patterns, internal waves, phytoplankton distribution, algae patchiness, oil pollution and high-resolution wind fields) need integration and combination with fine resolution numerical ocean models. Only via such integrated systems will realistic representation of the initial state be derived and properly utilized to provide reliable and accurate forecasts of, for instance, location of eddies, upwelling patterns, and high-concentration of toxic algae. The role of sar in such systems is addressed and characterized in terms of current status and further need for research and development. Use of synergetic remote sensing observations, in particular from optical remote sensing, is also considered in this context.

Lack of functional normalisation of tumour vessels following anti-angiogenic therapy in glioblastoma

Neo-angiogenesis represents an important factor for the delivery of oxygen and nutrients to a growing tumour, and is considered to be one of the main pathodiagnostic features of glioblastomas (GBM). Anti-angiogenic therapy by vascular endothelial growth factor (VEGF) blocking agents has been shown to lead to morphological vascular normalisation resulting in a reduction of contrast enhancement as seen by magnetic resonance imaging (MRI). Yet the functional consequences of this normalisation and its potential for improved delivery of cytotoxic agents to the tumour are not known. The presented study aimed at determining the early physiologic changes following bevacizumab treatment. A time series of perfusion MRI and hypoxia positron emission tomography (PET) scans were acquired during the first week of treatment, in two human GBM xenograft models treated with either high or low doses of bevacizumab. We show that vascular morphology was normalised over the time period investigated, but vascular function was not improved, resulting in poor tumoural blood flow and increased hypoxia.