Peritumoral Brain Zone Research Articles

Down-regulation of 14-3-3 zeta sensitizes human glioblastoma cells to apoptosis induction.

Strong 14-3-3 zeta protein expression plays an important role in tumorigenesis, including in the maintenance of cell growth, resistance increase, and the prevention of apoptosis. In this study, we focus on two targets: (1) the expression of 14-3-3 zeta in the different grades of human astrocytoma (II-IV), (2) suppression of 14-3-3 zeta protein expression in glioblastoma derived astrocytes by 14-3-3 zeta shRNA lentiviral particles. The tissues of human astrocytoma were provided from 30 patients (ten of each grade of astrocytoma). Control tissues were obtained from the peritumoral brain zone of those patients with glioblastoma. The protein and mRNA expression levels of each astrocytoma grade were assessed via western blotting and RT-PCR, respectively. Results indicated that 14-3-3 zeta was significantly expressed in glioblastoma multiforme (grade IV) and 14-3-3 zeta expression levels enhanced according to the increase of astrocytoma malignancy. In the cellular study for knock down of the 14-3-3 zeta protein, surgical biopsy of glioblastoma was used to isolate primary astrocyte. Astrocytes were transduced with 14-3-3 zeta shRNA or non-targeted shRNA lentiviral particles. Furthermore, reduction of the 14-3-3 zeta protein expression in the astrocytes evaluated through qRT-PCR and western blot after transduction of 14-3-3 zeta shRNA lentiviral particles. Moreover, apoptosis properties, including DNA fragmentation and ratio increase of Bax/Bcl-2 were observed in astrocytes following reduction of 14-3-3 zeta protein expression. Further observation indicated that the mitochondrial pathway through release of cytochorome c and caspase-3 activity was involved in the apoptosis induction. Hence, this study demonstrates a key role of the 14-3-3 zeta protein in tumorigenesis but also indicates that 14-3-3 zeta can be considered as a target for the astrocytoma treatment specially glioblastoma.

Histopathological vascular investigation of the peritumoral brain zone of glioblastomas.

To date, no histopathological vascular investigation focusing on peritumoral brain zone (PBZ) has been reported for glioblastoma. We analyzed 10 newly diagnosed cases of glioblastomas. For these PBZs, histopathological investigation was performed by hematoxylin-eosin (H&E) staining and immunohistochemistry was analyzed for CD31, CD34, Factor VIII, VEGF, VEGFR-1/2, Ki67, p53 and nestin. Although it was difficult to identify PBZ by H&E, Ki67 and p53 staining, there were apparent differences in nestin staining among PBZ, tumor core (TC), and normal zone (NZ). Therefore, in this study, we divided PBZ from TC and NZ by nestin staining. Differences in histological features, microvessel density, expression of VEGF and its receptors were assessed for PBZ, TC and NZ. The microvessel density, as determined by counting CD31, CD34 and VEGF receptors, and VEGF-A expression were lower in PBZ than TC. The expression patterns for CD31, CD34 and VEGF receptors in vessels show dissociation in PBZ. In addition, the vascular characteristics of the PBZ may correlate with findings of radiographic imaging. We provide the first clinicopathological evidence that PBZ exhibits unique angiogenic characteristics. These in situ observations will help to elucidate the mechanisms of tumor recurrence.

Erratum to: Radiomic features from the peritumoral brain parenchyma on treatment-naïve multi-parametric MR imaging predict long versus short-term survival in glioblastoma multiforme: Preliminary findings.

Despite 90 % of glioblastoma (GBM) recurrences occurring in the peritumoral brain zone (PBZ), its contribution in patient survival is poorly understood. The current study leverages computerized texture (i.e. radiomic) analysis to evaluate the efficacy of PBZ features from pre-operative MRI in predicting long- (>18 months) versus short-term (<7 months) survival in GBM. Sixty-five patient examinations (29 short-term, 36 long-term) with gadolinium-contrast T1w, FLAIR and T2w sequences from the Cancer Imaging Archive were employed. An expert manually segmented each study as: enhancing lesion, PBZ and tumour necrosis. 402 radiomic features (capturing co-occurrence, grey-level dependence and directional gradients) were obtained for each region. Evaluation was performed using threefold cross-validation, such that a subset of studies was used to select the most predictive features, and the remaining subset was used to evaluate their efficacy in predicting survival. A subset of ten radiomic ‘peritumoral’ MRI features, suggestive of intensity heterogeneity and textural patterns, was found to be predictive of survival (p = 1.47 × 10-5) as compared to features from enhancing tumour, necrotic regions and known clinical factors. Our preliminary analysis suggests that radiomic features from the PBZ on routine pre-operative MRI may be predictive of long- versus short-term survival in GBM. • Radiomic features from peritumoral regions can capture glioblastoma heterogeneity to predict outcome. • Peritumoral radiomics along with clinical factors are highly predictive of glioblastoma outcome. • Identifying prognostic markers can assist in making personalized therapy decisions in glioblastoma.

Applying protein-based amide proton transfer MR imaging to distinguish solitary brain metastases from glioblastoma.

To determine the utility of amide proton transfer-weighted (APTw) MR imaging in distinguishing solitary brain metastases (SBMs) from glioblastomas (GBMs). Forty-five patients with SBMs and 43 patients with GBMs underwent conventional and APT-weighted sequences before clinical intervention. The APTw parameters and relative APTw (rAPTw) parameters in the tumour core and the peritumoral brain zone (PBZ) were obtained and compared between SBMs and GBMs. The receiver-operating characteristic (ROC) curve was used to assess the best parameter for distinguishing between the two groups. The APTwmax, APTwmin, APTwmean, rAPTwmax, rAPTwmin or rAPTwmean values in the tumour core were not significantly different between the SBM and GBM groups (P = 0.141, 0.361, 0.221, 0.305, 0.578 and 0.448, respectively). However, the APTwmax, APTwmin, APTwmean, rAPTwmax, rAPTwmin or rAPTwmean values in the PBZ were significantly lower in the SBM group than in the GBM group (P < 0.001). The APTwmin values had the highest area under the ROC curve 0.905 and accuracy 85.2% in discriminating between the two neoplasms. As a noninvasive imaging method, APT-weighted MR imaging can be used to distinguish SBMs from GBMs. • APTw values in the tumour core were not different between SBMs and GBMs. • APTw values in peritumoral brain zone were lower in SBMs than in GBMs. • The APTw min was the best parameter to distinguish SBMs from GBMs.

Radiomic features from the peritumoral brain parenchyma on treatment-naïve multi-parametric MR imaging predict long versus short-term survival in glioblastoma multiforme: Preliminary findings.

Despite 90% of glioblastoma (GBM) recurrences occurring in the peritumoral brain zone (PBZ), its contribution in patient survival is poorly understood. The current study leverages computerized texture (i.e. radiomic) analysis to evaluate the efficacy of PBZ features from pre-operative MRI in predicting long- (>18months) versus short-term (<7months) survival in GBM. Sixty-five patient examinations (29 short-term, 36 long-term) with gadolinium-contrast T1w, FLAIR and T2w sequences from the Cancer Imaging Archive were employed. An expert manually segmented each study as: enhancing lesion, PBZ and tumour necrosis. 402 radiomic features (capturing co-occurrence, grey-level dependence and directional gradients) were obtained for each region. Evaluation was performed using threefold cross-validation, such that a subset of studies was used to select the most predictive features, and the remaining subset was used to evaluate their efficacy in predicting survival. A subset of ten radiomic 'peritumoral' MRI features, suggestive of intensity heterogeneity and textural patterns, was found to be predictive of survival (p = 1.47 × 10-5) as compared to features from enhancing tumour, necrotic regions and known clinical factors. Our preliminary analysis suggests that radiomic features from the PBZ on routine pre-operative MRI may be predictive of long- versus short-term survival in GBM. • Radiomic features from peritumoral regions can capture glioblastoma heterogeneity to predict outcome. • Peritumoral radiomics along with clinical factors are highly predictive of glioblastoma outcome. • Identifying prognostic markers can assist in making personalized therapy decisions in glioblastoma.

A state-of-the-art review and guidelines for tumor treating fields treatment planning and patient follow-up in glioblastoma.

Tumor treating fields (TTFields) are an integral treatment modality in the management of glioblastoma and extend overall survival when combined with maintenance temozolomide in newly diagnosed patients. Complexities exist regarding correct selection of imaging sequences with which to perform TTFields treatment planning. Guidelines are warranted first, to facilitate treatment planning standardization across medical disciplines and institutions, to ensure optimal TTFields delivery to the tumor and peritumoral brain zone while maximizing patient safety, and also to mitigate the risk of premature cessation of a potentially beneficial treatment. This summary guideline outlines methods for starting patients on TTFields, for monitoring patient response to therapy and provides a framework for evaluating when therapy should be re-planned, based on the extent of sequential imaging changes.

332 Molecular Characteristics of Tumor Infiltrating Front in Glioblastoma

INTRODUCTION: Molecular heterogeneity in glioblastoma (GBM) is a novel area of research recently. Because tumor infiltrating front in GBM is often left behind following tumor decompression, knowledge of its genetic makeup can improve the rationale of potential molecular targets. METHODS: MRI localized biopsies of the tumor core and peritumoral brain zone (PBZ) were obtained from 25 GBM patients. The PBZ samples containing 15% to 30% tumor cells and core samples with predominantly tumor cells along with 8 nonneoplastic brain tissues were selected for a whole Genome Gene Expression Microarray. The list of differentially expressed genes between the tumor core and PBZ compared with nonneoplastic brain tissue was identified using R Bioconductor. Selected genes were validated using quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry (IHC). RESULTS: Unsupervised hierarchical clustering of the genes revealed that the tumor core and PBZ samples showed a varied gene expression profile and clustered into 2 distinct groups. Approximately 7123, 5188, and 991 genes were differentially expressed in Core vs Normal, PBZ vs Normal and PBZ vs Core. Novel genes like PBK (role in cell cycle), MELK (stem cell marker), and TOP2A (proliferation marker) were upregulated in PBZ and tumor core compared with normal brain and robustly validated on IHC. Pathways involved in cell cycle, immune response, cell-cell adhesion, cell-matrix interaction, etc, were commonly enriched in periphery and tumor core compared with normal brain. Some of the novel markers were validated by real-time PCR and IHC. CONCLUSION: We demonstrate that the key genes involved in tumor cell proliferation, invasion, migration, response to immune system, and stemness markers are highly enriched in the PBZ. These genes, probably contribute to the resistance of PBZ cells to standard adjuvant therapy, resulting in tumor recurrence.

Abstract 2051: Tumor-treating fields (TTFields) intensity in the gross tumor volume and peritumoral brain zone: implications for local recurrence in glioblastoma

Abstract The purpose of this study was to simulate the intensity of TTFields delivered to the brain during the course of glioblastoma (GBM) treatment and to determine whether therapeutic intensities are delivered to the proximal peri-tumoral brain zone (PBZ). Background: TTFields are low-intensity (1-3 V/cm), intermediate frequency (200kHz), alternating electric fields delivered orthogonally in a localized manner during the course of GBM therapy. A recent phase 3 randomized, controlled trial conducted in patients newly diagnosed with GBM was stopped early for efficacy when the end points for progression-free survival (PFS) and overall survival (OS) were met at the interim analysis. Patients receiving TTFields in combination with temozolomide (TMZ) had a significantly longer PFS and OS compared with patients receiving TMZ alone. More than 90% of GBM recur at the margin of a resection cavity or within the PBZ where the presence of infiltrating tumor cells, inflammatory cells and tumorigenic stromal cells are thought to promote recurrence. Phantom model simulation studies suggest that field intensities &amp;gt;1V/cm are delivered to the brain in a non-uniform distribution, however the field distribution to the gross tumor volume (GTV) and PBZ have not been previously evaluated. Methods: Two MRI cases (frontal and posterior-parietal tumors) were used to generate TTFields treatment array layout maps using NovoTAL(TM) System planning software, targeting areas of contrast enhancement on T1 sequences. Simulations for the respective array layouts were created for solid tumors, resection cavities and for tumors with a necrotic core (modified Colin27 model, meshed and solved using the Sim4Life software solver package). Two orthogonal fields (left-right and antero-posterior) at a field frequency of 200 kHz were employed for all simulations. Field intensity was determined in the GTV, tumor margin(TM) and proximal PBZ (20mm) for all models. Results: Transducer array layout maps generated by the NovoTAL software deliver therapeutic intensities of TTFields in both L-R and A-P directions. Bi-directional intensities exceed therapeutic levels (&amp;gt;1 V/cm) in the GTV (median 1.84 V/cm), TM (median 1.9 V/cm) and PBZ (median 2.09 V/cm) in all solid tumors and in the PBZ (median 1.83 V/cm) surrounding a gross total resection (GTR) cavity. The highest areas of field intensity are observed directly adjacent to resection cavities and the ventricles. Conclusions: The delivery of therapeutic intensities of TTFields to patients who have undergone a GTR, subtotal resection or who have inoperable GBM, targets therapy to the area of active disease and importantly, to the PBZ. TTFields target residual tumor cells in the GTV and may also disrupt infiltrating tumor cells in the PBZ. Clinically, this may decrease local GBM recurrence rates and prospective clinical studies are warranted to explore this further. Citation Format: Aafia Chaudhry, Zeev Bomzon, Hadas Sara Hershkovich, Dario Garcia-Carracedo, Cornelia Wenger, Uri Weinberg, Yoram Palti. Tumor-treating fields (TTFields) intensity in the gross tumor volume and peritumoral brain zone: implications for local recurrence in glioblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2051.

Intratumoral heterogeneity in glioblastoma: don't forget the peritumoral brain zone.

Glioblastoma (GB) is the most frequent and aggressive primary tumor of the central nervous system. Prognosis remains poor despite ongoing progress. In cases where the gadolinium-enhanced portion of the GB is completely resected, 90% of recurrences occur at the margin of surgical resection in the macroscopically normal peritumoral brain zone (PBZ). Intratumoral heterogeneity in GB is currently a hot topic in neuro-oncology, and the GB PBZ may be involved in this phenomenon. Indeed, this region, which possesses specific properties, has been less studied than the core of the GB tumor. The high rate of local recurrence in the PBZ and the limited success of targeted therapies against GB demonstrate the need for a better understanding of the PBZ. We present here a review of the literature on the GB PBZ, focusing on its radiological, cellular, and molecular characteristics. We discuss how intraoperative analysis of the PBZ is important for the optimization of surgical resection and the development of targeted therapies against GB.

Characterizing the peritumoral brain zone in glioblastoma: a multidisciplinary analysis

Glioblastoma (GB) is the most frequent and aggressive type of primary brain tumor. Recurrences are mostly located at the margin of the resection cavity in the peritumoral brain zone (PBZ). Although it is widely believed that infiltrative tumor cells in this zone are responsible for GB recurrence, few studies have examined this zone. In this study, we analyzed PBZ left after surgery with a variety of techniques including radiology, histopathology, flow cytometry, genomic, transcriptomic, proteomic, and primary cell cultures. The resulting PBZ profiles were compared with those of the GB tumor zone and normal brain samples to identify characteristics specific to the PBZ. We found that tumor cell infiltration detected by standard histological analysis was present in almost one third of PBZ taken from an area that was considered normal both on standard MRI and by the neurosurgeon under an operating microscope. The panel of techniques used in this study show that the PBZ, similar to the tumor zone itself, is characterized by substantial inter-patient heterogeneity, which makes it difficult to identify representative markers. Nevertheless, we identified specific alterations in the PBZ such as the presence of selected tumor clones and stromal cells with tumorigenic and angiogenic properties. The study of GB-PBZ is a growing field of interest and this region needs to be characterized further. This will facilitate the development of new, targeted therapies for patients with GB and the development of approaches to refine the per-operative evaluation of the PBZ to optimize the surgical resection of the tumor.

P16.20 * ANALYSIS OF GLIOBLASTOMA'S PERITUMORAL BRAIN ZONE USING BIPHOTONIC MICROSCOPY

Glial tumors are primary tumors of the central nervous system. Gross total resection (GTR) of the tumor is the first step of its therapeutic management. Several techniques of per-operative analysis of the margin of the peritumoral brain zone (PBZ) have been developed in order to ensure a GTR of the tumor. We present here a new approach to the per-operative analysis of the PBZ using biphotonic microscopy analysis, a method allowing a fast and reproducible analysis of brain sample tissues. GB tumor zone, low-grade glioma and their respective PBZ were fixed on paraffine-embedded slices. These slices were analyzed using second harmonic generation microscopy (SHG) and two-photon excitation fluorescence (TPEF) microscopy. Data were collected and interpreted using a custom-wricen program with Labview, and compared to the histopathological diagnosis made by a certified neuropathologist. Each kind of brain tumor tissue and PBZ displayed a specific pattern in SHG and TPEF imaging. Also, distinction between tumor and PBZ was easy in SHG and TPEF analysis, allowing a clear vizualisation of the brain/tumor interface. SHG and TPEF imaging are fast and efficient methods allowing per-operative analysis of brain tumor tissue. The next step of our study will be to create an atlas of SHG and TPEF profile of the different brain tumors to allow direct per-operative analysis of PBZ without waiting for the pathological diagnosis, to ensure an optimal resection's quality.

Proteomic analysis of glioblastomas: What is the best brain control sample?

Glioblastoma (GB) is the most frequent and aggressive tumor of the central nervous system. There is currently growing interest in proteomic studies of GB, particularly with the aim of identifying new prognostic or therapeutic response markers. However, comparisons between different proteomic analyses of GB have revealed few common differentiated proteins. The types of control samples used to identify such proteins may in part explain the different results obtained. We therefore tried to determine which control samples would be most suitable for GB proteomic studies. We used an isotope-coded protein labeling (ICPL) method followed by mass spectrometry to reveal and compare the protein patterns of two commonly used types of control sample: GB peritumoral brain zone samples (PBZ) from six patients and epilepsy surgery brain samples (EB) pooled from three patients. The data obtained were processed using AMEN software for network analysis. We identified 197 non-redundant proteins and 35 of them were differentially expressed. Among these 35 differentially expressed proteins, six were over-expressed in PBZ and 29 in EB, showing different proteomic patterns between the two samples. Surprisingly, EB appeared to display a tumoral-like expression pattern in comparison to PBZ. In our opinion, PBZ may be more appropriate control sample for GB proteomic analysis. This manuscript describes an original study in which we used an isotope-coded protein labeling method followed by mass spectrometry to identify and compare the protein patterns in two types of sample commonly used as control for glioblastoma (GB) proteomic analysis: peritumoral brain zone and brain samples obtained during surgery for epilepsy. The choice of control samples is critical for identifying new prognostic and/or diagnostic markers in GB.