Changes in the biological characteristics of glioma cancer stem cells after serial in vivo subtransplantation

PURPOSE

Currently, the interaction between the niche and glioma cancer stem cells (gCSCs) is gaining attention. However, there are few studies concerned with the effects of repeated exposure to a new microenvironment on gCSCs characteristics. In this study, serial in vivo subtransplantation was performed to create a new microenvironment. We evaluated and compared the biological characteristics of gCSCs after serial in vivo subtransplantation.

METHODS

We cultured gCSCs from human glioma specimens according to cultured gliomasphere methods. The isolated gCSCs were termed zero-generation gCSCs (G0-gCSCs). By subsequent serial subtransplantation, we obtained first-generation gCSCs (G1-gCSCs) and second-generation gCSCs (G2-gCSCs). We evaluated and compared the biological characteristics of G0-gCSCs, G1-gCSCs, and G2-gCSCs. The in vitro characteristics included the morphology, surface marker profiles, and neural differentiation capacity and the in vivo characteristics was the survival of mice xenografts. Additionally, brain sections were analyzed using PCNA, TUNEL, and CD31 staining.

RESULTS

We observed no significant differences in the in vitro characteristics of G0-gCSCs, G1-gCSCs, and G2-gCSCs. However, the survival time of mice glioma xenografts was significantly decreased upon serial subtransplantation. In addition, immunohistochemical analyses showed that the number of TUNEL(+) cells was significantly decreased while the number of CD31(+) cells was significantly increased with serial in vivo subtransplantation.

CONCLUSIONS

There were significant in vivo biological changes in gCSCs upon serial in vivo subtransplantation, which were shorter xenograft survival, increased angiogenesis, and decreased apoptosis. This study suggests that the repeated exposure to new microenvironments may affect the biological changes in gCSCs in vivo.

Chromosome 19 annotations with disease speciation: a first report from the Global Research Consortium

A first research development progress report of the Chromosome 19 Consortium with members from Sweden, Norway, Spain, United States, China and India, a part of the Chromosome-centric Human Proteome Project (C-HPP) global initiative, is presented ( http://www.c-hpp.org ). From the chromosome 19 peptide-targeted library constituting 6159 peptides, a pilot study was conducted using a subset with 125 isotope-labeled peptides. We applied an annotation strategy with triple quadrupole, ESI-Qtrap, and MALDI mass spectrometry platforms, comparing the quality of data within and in between these instrumental set-ups. LC-MS conditions were outlined by multiplex assay developments, followed by MRM assay developments. SRM was applied to biobank samples, quantifying kallikrein 3 (prostate specific antigen) in plasma from prostate cancer patients. The antibody production has been initiated for more than 1200 genes from the entire chromosome 19, and the progress developments are presented. We developed a dedicated transcript microarray to serve as the mRNA identifier by screening cancer cell lines. NAPPA protein arrays were built to align with the transcript data with the Chromosome 19 NAPPA chip, dedicated to 90 proteins, as the first development delivery. We have introduced an IT-infrastructure utilizing a LIMS system that serves as the key interface for the research teams to share and explore data generated within the project. The cross-site data repository will form the basis for sample processing, including biological samples as well as patient samples from national Biobanks.

REST regulates oncogenic properties of glioblastoma stem cells

Glioblastoma multiforme (GBM) tumors are the most common malignant primary brain tumors in adults. Although many GBM tumors are believed to be caused by self-renewing, glioblastoma-derived stem-like cells (GSCs), the mechanisms that regulate self-renewal and other oncogenic properties of GSCs are only now being unraveled. Here we showed that GSCs derived from GBM patient specimens express varying levels of the transcriptional repressor repressor element 1 silencing transcription factor (REST), suggesting heterogeneity across different GSC lines. Loss- and gain-of-function experiments indicated that REST maintains self-renewal of GSCs. High REST-expressing GSCs (HR-GSCs) produced tumors histopathologically distinct from those generated by low REST-expressing GSCs (LR-GSCs) in orthotopic mouse brain tumor models. Knockdown of REST in HR-GSCs resulted in increased survival in GSC-transplanted mice and produced tumors with higher apoptotic and lower invasive properties. Conversely, forced expression of exogenous REST in LR-GSCs produced decreased survival in mice and produced tumors with lower apoptotic and higher invasive properties, similar to HR-GSCs. Thus, based on our results, we propose that a novel function of REST is to maintain self-renewal and other oncogenic properties of GSCs and that REST can play a major role in mediating tumorigenicity in GBM.

IDH1 status and survival benefit from surgical resection of enhancing and nonenhancing tumor in malignant astrocytomas

2019

Background: The value of maximal safe resection for malignant astrocytic gliomas (AA, WHO Grade III anaplastic astrocytoma and GBM, WHO Grade IV glioblastoma) has sometimes been controversial, because of confounding between measures of surgical resection and other prognostic factors. IDH1 gene mutations are associated with improved survival in glioma patients, and are thought to identify tumors with a distinct molecular evolutionary origin. We sought to determine the prognostic impact of surgical resection on survival after controlling for IDH1 status in malignant astrocytomas. Methods: Clinical parameters including preoperative and postoperative MRI-based tumor volume were recorded prospectively on 407 malignant astrocytoma patients – AA (n=157) and GBM (n=250). IDH1 status was assessed by sequencing and R132H-specific immunohistochemistry. Results: The measures of surgical resection associated with longer survival differed between IDH1 wild-type and mutant tumors. In multivariate analyses of IDH1 wild-type tumors (controlling for age, Karnofsky performance score, tumor location, and tumor grade), residual postoperative enhancement was associated with a median survival of 9.9 mo vs. 17.4 mo with no enhancement (HR=1.73, 95% CI, 1.19-2.52, p=.004). Residual non-enhancing disease, however, was not associated with survival (scored as continuous volumetric cc, 95% CI 0.99-1.01, p=.608). These results are consistent with prior studies of GBM, which are largely IDH1 wild-type lesions (Lacroix et al., J Neurosurg 95:190-8, 2001). In contrast, in IDH1 mutant tumors, both residual enhancing (HR=7.93, 95%CI 1.14-55.22, p=.037) and non-enhancing (HR=1.03, 95% CI 1.01-1.05, p=.005) postoperative tumor burden were associated with worse survival. Conclusions: These data suggest surgical resection in malignant astrocytic gliomas may be individualized based on IDH1 genotype. IDH1 mutant tumors have a better baseline overall prognosis, therefore more aggressive surgery and tolerance of temporary peri-operative neurologic deficits can be weighed in an attempt to gain the additional survival benefit that appears to be associated with reducing non-enhancing tumor burden.

The transcriptional coactivator TAZ regulates mesenchymal differentiation in malignant glioma

Recent molecular classification of glioblastoma (GBM) has shown that patients with a mesenchymal (MES) gene expression signature exhibit poor overall survival and treatment resistance. Using regulatory network analysis of available expression microarray data sets of GBM, including The Cancer Genome Atlas (TCGA), we identified the transcriptional coactivator with PDZ-binding motif (TAZ), to be highly associated with the MES network. TAZ expression was lower in proneural (PN) GBMs and lower-grade gliomas, which correlated with CpG island hypermethylation of the TAZ promoter compared with MES GBMs. Silencing of TAZ in MES glioma stem cells (GSCs) decreased expression of MES markers, invasion, self-renewal, and tumor formation. Conversely, overexpression of TAZ in PN GSCs as well as murine neural stem cells (NSCs) induced MES marker expression and aberrant osteoblastic and chondrocytic differentiation in a TEAD-dependent fashion. Using chromatin immunoprecipitation (ChIP), we show that TAZ is directly recruited to a majority of MES gene promoters in a complex with TEAD2. The coexpression of TAZ, but not a mutated form of TAZ that lacks TEAD binding, with platelet-derived growth factor-B (PDGF-B) resulted in high-grade tumors with MES features in a murine model of glioma. Our studies uncover a direct role for TAZ and TEAD in driving the MES differentiation of malignant glioma.

Neurocognitive function before and after surgery for insular gliomas

Object

Insular gliomas can be resected with acceptable rates of neurological morbidity, but little is known with regard to impairment of higher-order neurocognitive functions. The frequency and functional impact of neurocognitive deficits in patients with gliomas has until recently been underappreciated. The authors therefore examined neurocognitive function in patients with insular gliomas and compared the findings in this group to those in a matched control group of patients with gliomas in nearby brain regions.

Methods

Thirty-three patients with WHO Grade II or III insular gliomas participated in neuropsychological evaluations before and after resection. To establish whether the pattern of neurocognitive performance was different from that of other patients with tumors in neighboring areas, patients with insular tumors were matched with control patients for age, educational level, preoperative Karnofsky Performance Scale score, tumor side, grade, and volume. The control group comprised patients in whom gliomas had been resected from frontal, temporal, and parietal areas near the insula. Baseline pre- and postoperative neurocognitive test results were compared between and within groups.

Results

Preoperative neurocognitive impairment was common in both insular and control groups. Patients with insular tumors had significantly worse preoperative performance on naming tests. In both groups, postoperative decline occurred in most neurocognitive domains. There were no statistically significant differences between patients in the insular and control groups with regard to rates of postoperative decline on any test. However, there were trends suggesting differential cognitive performance postoperatively, because patients with insular tumors were more likely to experience greater decline in learning and memory. Neurological morbidity was similar to prior rates reported in the literature.

Conclusions

Few statistically significant differences in cognitive function were observed between patients in the insular and control groups at either the pre- or postoperative evaluation, although there was a trend for patients with insular tumors to exhibit greater postoperative decline in learning and memory. Although technically more challenging, surgery for insular region glioma appears feasible without profound neurological or cognitive morbidity for many patients.

Genetic and epigenetic modifications of Sox2 contribute to the invasive phenotype of malignant gliomas

We undertook this study to understand how the transcription factor Sox2 contributes to the malignant phenotype of glioblastoma multiforme (GBM), the most aggressive primary brain tumor. We initially looked for unbalanced genomic rearrangements in the Sox2 locus in 42 GBM samples and found that Sox2 was amplified in 11.5% and overexpressed in all the samples. These results prompted us to further investigate the mechanisms involved in Sox2 overexpression in GBM. We analyzed the methylation status of the Sox2 promoter because high CpG density promoters are associated with key developmental genes. The Sox2 promoter presented a CpG island that was hypomethylated in all the patient samples when compared to normal cell lines. Treatment of Sox2-negative glioma cell lines with 5-azacitidine resulted in the re-expression of Sox2 and in a change in the methylation status of the Sox2 promoter. We further confirmed these results by analyzing data from GBM cases generated by The Cancer Genome Atlas project. We observed Sox2 overexpression (86%; N = 414), Sox2 gene amplification (8.5%; N = 492), and Sox 2 promoter hypomethylation (100%; N = 258), suggesting the relevance of this factor in the malignant phenotype of GBMs. To further explore the role of Sox2, we performed in vitro analysis with brain tumor stem cells (BTSCs) and established glioma cell lines. Downmodulation of Sox2 in BTSCs resulted in the loss of their self-renewal properties. Surprisingly, ectopic expression of Sox2 in established glioma cells was not sufficient to support self-renewal, suggesting that additional factors are required. Furthermore, we observed that ectopic Sox2 expression was sufficient to induce invasion and migration of glioma cells, and knockdown experiments demonstrated that Sox2 was essential for maintaining these properties. Altogether, our data underscore the importance of a pleiotropic role of Sox2 and suggest that it could be used as a therapeutic target in GBM.

Glioblastoma angiogenesis and tumor cell invasiveness are differentially regulated by β8 integrin

Glioblastoma multiforme (GBM) is a highly invasive brain tumor that develops florid microvascular proliferation and hemorrhage. However, mechanisms that favor invasion versus angiogenesis in this setting remain largely uncharacterized. Here, we show that integrin β8 is an essential regulator of both GBM-induced angiogenesis and tumor cell invasiveness. Highly angiogenic and poorly invasive tumors expressed low levels of β8 integrin, whereas highly invasive tumors with limited neovascularization expressed high levels of β8 integrin. Manipulating β8 integrin protein levels altered the angiogenic and invasive growth properties of GBMs, in part, reflected by a diminished activation of latent TGFβs, which are extracellular matrix protein ligands for β8 integrin. Taken together, these results establish a role for β8 integrin in differential control of angiogenesis versus tumor cell invasion in GBM. Our findings suggest that inhibiting β8 integrin or TGFβ signaling may diminish tumor cell invasiveness during malignant progression and following antivascular therapies.

Clinical outcome of leukemia patients with intracranial hemorrhage

Object

Intracranial hemorrhage (ICH) is a frequent complication found in leukemia patients with thrombocytopenia. At the University of Texas MD Anderson Cancer Center, when a leukemia patient is found to have ICH, a platelet transfusion is generally recommended until 50,000/μl is reached. The authors examine the feasibility and outcome of their intervention strategy in this study.

Methods

Records were reviewed from 76 consecutive leukemia patients with newly diagnosed ICH at the University of Texas MD Anderson Cancer Center from January 1, 2007, to December 31, 2009. Variables of interest included age, platelet count at presentation, leukemia subtype, history of trauma, Glasgow Coma Scale score at presentation, whether the 50,000/μl goal was reached after transfusion, and whether the patient was a transfusion responder (platelet count increase > 2000/μl/unit transfused). Outcome parameters were mortality rates at 72 hours and 30 days and imaging-documented hemorrhage progression.

Results

Thrombocytopenia was prevalent at the time of presentation (68 of 76 patients had platelet levels < 50,000/μl at presentation). Despite an aggressive transfusion protocol, only 24 patients reached the 50,000/μl target after an average of 16 units of transfusion. Death due to ICH occurred in 15 patients within the first 72 hours (mortality rate 19.7%). Death correlated with the presenting Glasgow Coma Scale score (p = 0.0075) but not with other transfusion-related parameters. A significant mortality rate was again observed after 30 days (32.7%). The 30-day mortality rate, however, was largely attributable to non-ICH related causes and correlated with patient age (p = 0.032) and whether the patient was a transfusion responder (p = 0.022). Reaching and maintaining a platelet count > 50,000/μl did not positively correlate with the 30-day mortality rate (p = 0.392 and 0.475, respectively).

Conclusions

Platelet transfusion in the setting of ICH in leukemia patients is undoubtedly necessary, but whether the transfusion threshold should be 50,000/μl remains unclear. Factors other than thrombocytopenia likely contribute to the overall poor prognosis.

Vorinostat modulates cell cycle regulatory proteins in glioma cells and human glioma slice cultures

Chromatin modification through histone deacetylase inhibition has shown evidence of activity against malignancies. The mechanism of action of such agents are pleiotropic and potentially tumor specific. In this study, we studied the mechanisms of vorinostat-induced cellular effects in gliomas. The effects of vorinostat on proliferation, induction of apoptosis and cell cycle effects were studied in vitro (D54, U87 and U373 glioma cell lines). To gain additional insights into its effects on human gliomas, vorinostat-induced changes were examined ex vivo using a novel organotypic human glioma slice model. Vorinostat treatment resulted in increased p21 levels in all glioma cells tested in a p53 independent manner. In addition, cyclin B1 levels were transcriptionally downregulated and resulted in reduced kinase activity of the cyclin B1/cdk1 complex causing a G2 arrest. These effects were associated with a dose- and time-dependent inhibition of cellular proliferation and anchorage-independent growth in association with hyperacetylation of core histones and induction of apoptosis. Of particular significance, we demonstrate histone hyperacetylation and increased p21 levels in freshly resected human glioma specimens maintained as organotypic slice cultures and exposed to vorinostat similar to cell lines suggesting that human glioma can be targeted by this agent. Our data suggest that the effects of vorinostat are associated with modulation of cell cycle related proteins and activation of a G2 checkpoint along with induction of apoptosis. These effects are mediated by both transcriptional and post-translational mechanisms which provide potential options that can be exploited to develop new therapeutic approaches against gliomas.

Isolation and perivascular localization of mesenchymal stem cells from mouse brain

BACKGROUND

Although originally isolated from the bone marrow, mesenchymal stem cells (MSCs) have recently been detected in other tissues. However, little is known about MSCs in the brain.

OBJECTIVE

To determine the extent to which cells with the features of MSCs exist in normal brain tissue and to determine the location of these cells in the brain.

METHODS

Single-cell suspensions from mouse brains were cultured according to the same methods used for culturing bone marrow-derived MSCs (BM-MSCs). These brain-derived cells were analyzed by fluorescence-activated cell sorting for surface markers associated with BM-MSCs (stem cell antigen 1 [Sca-1+], CD9+, CD45-, CD11b-, and CD31-). Brain-derived cells were exposed to mesenchymal differentiation conditions. To determine the locations of these cells within the brain, sections of normal brains were analyzed by immunostaining for Sca-1, CD31, and nerve/glial antigen 2.

RESULTS

Cells morphologically similar to mouse BM-MSCs were identified and called brain-derived MSCs (Br-MSCs). Fluorescence-activated cell sorting indicated that the isolated cells had a surface marker profile similar to BM-MSCs, ie, Sca-1V+, CD9+, CD45-, and CD11b-. Like BM-MSCs, Br-MSCs were capable of differentiation into adipocytes, osteocytes, and chondrocytes. Immunostaining indicated that Sca-1+ Br-MSCs are located around blood vessels and may represent progenitor cells that serve as a source of mesenchymal elements (eg, pericytes) within the brain.

CONCLUSION

Our results indicate that cells similar to BM-MSCs exist in the brain. These Br-MSCs appear to be located within the vascular niche and may provide the mesenchymal elements of this niche. Because MSCs may be part of the cellular response to tissue injury, Br-MSCs may represent targets in the therapy of pathological processes such as stroke, trauma, and tumorigenesis.

Abstract LB-114: Molecular and lineage analysis of glioblastoma stem cells identifies clinically relevant models of glioblatoma

The Cancer Genome Atlas project described a robust gene expression-based molecular classification of GBM. However, the functional and biological significance of the molecular subclasses are being determined. In this study, we hypothesize that Glioma Stem Cells (GSCs) isolated from individual patient tumor samples will recapitulate the molecular characteristics of tumor samples and provide a relevant model for functional analysis of the molecular subclasses. Thus we conducted a comprehensive analysis of 26 GSC lines with expression array, RPPA, and a series of neural lineage markers. Analysis of the expression data classified the 26 GSC lines into four subtypes (Classical, Proneural 1, Proneural 2 and Mesenchymal,) closely similar to the TCGA subclasses with a distinct profile for each subtype (c-Myc, Cyclin D2 for Classical; Olig2, NKX2–2, Notch-1, Notch-3 for Proneural 2; BMP4, DCX, p16INK4a, ID2 for Proneural 1; CD44, CAV1, TGFBR2 for Mesenchymal). Further analysis showed that GSC subtypes exhibit divergent patterns of signaling pathway activation. The major pathways activated in 4 subtypes were Notch pathway in Proneural 2, Wnt/β-Catenin in Proneural 2 and Classical, while FGF/VEGF and TGF-β in Mesenchymal. In vitro treatment with SB 431542, a TGF-βR inhibitor, showed that Mesenchymal subtype is more sensitive than other subtypes. More importantly, lineage analysis of GSCs subtypes show that Proneural and Classical GSCs differentially express lineage markers for neural stem/progenitor cells and were responsive to differentiating agent retinoic acid. In addition, GSC subtypes exhibit distinct biological behaviors in self-renewal capacity, proliferation, invasiveness, angiogenic potential, response to growth factor stimulus, and differentiation in vitro and in vivo with Classical subtype being more proliferative and Mesenchymal subtype being more angiogenic and invasive.

In conclusion, our comprehensive analysis showed that GSCs reflect patient tumor subclass and these subtypes showed distinct regulatory pathway activation, lineage profile and biological behaviors. Thus GSC is biologically and molecularly a more relevant model system for preclinical studies of therapeutic intervention and to expand our molecular understanding of human GBM.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-114. doi:10.1158/1538-7445.AM2011-LB-114

Multiple craniotomies in the management of multifocal and multicentric glioblastoma

Object

Multiple craniotomies have been performed for resection of multiple brain metastases in the same surgical session with satisfactory outcomes, but the role of this procedure in the management of multifocal and multicentric glioblastomas is undetermined, although it is not the standard approach at most centers.

Methods

The authors performed a retrospective analysis of data prospectively collected between 1993 and 2008 in 20 patients with multifocal or multicentric glioblastomas (Group A) who underwent resection of all lesions via multiple craniotomies during a single surgical session. Twenty patients who underwent resection of solitary glioblastoma (Group B) were selected to match Group A with respect to the preoperative Karnofsky Performance Scale (KPS) score, tumor functional grade, extent of resection, age at time of surgery, and year of surgery. Clinical and neurosurgical outcomes were evaluated.

Results

In Group A, the median age was 52 years (range 32–78 years); 70% of patients were male; the median preoperative KPS score was 80 (range 50–100); and 9 patients had multicentric glioblastomas and 11 had multifocal glioblastomas. Aggressive resection of all lesions in Group A was achieved via multiple craniotomies in the same session, with a median extent of resection of 100%. Groups A and B were comparable with respect to all the matching variables as well as the amount of tumor necrosis, number of cysts, and the use of intraoperative navigation. The overall median survival duration was 9.7 months in Group A and 10.5 months in Group B (p = 0.34). Group A and Group B (single craniotomy) had complication rates of 30% and 35% and 30-day mortality rates of 5% (1 patient) and 0%, respectively.

Conclusions

Aggressive resection of all lesions in selected patients with multifocal or multicentric glioblastomas resulted in a survival duration comparable with that of patients undergoing surgery for a single lesion, without an associated increase in postoperative morbidity. This finding may indicate that conventional wisdom of a minimal role for surgical treatment in glioblastoma should at least be questioned.

Systemic combinatorial peptide selection yields a non-canonical iron-mimicry mechanism for targeting tumors in a mouse model of human glioblastoma

The management of CNS tumors is limited by the blood-brain barrier (BBB), a vascular interface that restricts the passage of most molecules from the blood into the brain. Here we show that phage particles targeted with certain ligand motifs selected in vivo from a combinatorial peptide library can cross the BBB under normal and pathological conditions. Specifically, we demonstrated that phage clones displaying an iron-mimic peptide were able to target a protein complex of transferrin and transferrin receptor (TfR) through a non-canonical allosteric binding mechanism and that this functional protein complex mediated transport of the corresponding viral particles into the normal mouse brain. We also showed that, in an orthotopic mouse model of human glioblastoma, a combination of TfR overexpression plus extended vascular permeability and ligand retention resulted in remarkable brain tumor targeting of chimeric adeno-associated virus/phage particles displaying the iron-mimic peptide and carrying a gene of interest. As a proof of concept, we delivered the HSV thymidine kinase gene for molecular-genetic imaging and targeted therapy of intracranial xenografted tumors. Finally, we established that these experimental findings might be clinically relevant by determining through human tissue microarrays that many primary astrocytic tumors strongly express TfR. Together, our combinatorial selection system and results may provide a translational avenue for the targeted detection and treatment of brain tumors.

A novel technique for planning surgical approaches to the pineal region by using external cranial landmarks

Object

The infratentorial supracerebellar approach to the pineal region presents special challenges during patient positioning. The head must be flexed and the body positioned to allow an operative trajectory under the straight sinus. Image guidance is not useful during positioning because registration and navigation take place after the head is fixed in its final position. Therefore, a reliable method of positioning based on external, easily identifiable landmarks to estimate the surgical trajectory along the straight sinus toward the pineal region is needed. Based on observation, the authors hypothesized that a line between 2 palpable external landmarks, the inion and the bregma, often approximates the surgical trajectory along the straight sinus. They tested this hypothesis by quantifying the relationship between the straight sinus and the bregma, and describe a method for estimating the working angle during patient positioning.

Methods

The midsagittal, Gd-enhanced, T1-weighted MR images of 102 patients were analyzed. Demographic data and the presence or absence of tentorial pathological entities was recorded. The slant of the straight sinus was classified as common, high, or low, based on a previously described classification system. A line along the bottom of the straight sinus (that is, the straight-sinus line) was extended superiorly to its intersection with the calvaria, and the distance from this intersection point to the bregma was measured.

Results

The intersection point of the straight-sinus line and the calvaria was on average 2 ± 8.2 mm (these values are expressed as the mean ± SD throughout) anterior to the bregma (range 19.9 mm anterior to 19.1 mm posterior). The distance from the intersection point to the bregma was not statistically significantly different in younger or older patients, or in patients with or without tumors involving the pineal region. In patients with a low slant of the straight sinus, the intersection point was 5.3 ± 6.3 mm anterior to the bregma, whereas in patients with a high slant of the straight sinus, the intersection point was 0.21 ± 9.1 mm posterior to the bregma (p = 0.015).

Conclusions

The straight-sinus line, which defines the working angle for the supracerebellar infratentorial approach, intersects the calvaria very close to the bregma in the majority of patients. Therefore, ideal patient positioning can be achieved by flexing the patient's head to optimize the working angle defined by an imaginary line connecting the torcula (inion) to the bregma.

Factors influencing the risk of local recurrence after resection of a single brain metastasis

OBJECT

Local recurrence (LR) of a resected brain metastasis occurs in up to 46% of patients. Postoperative whole-brain radiation therapy (WBRT) reduces that incidence. To isolate factors associated with the risk of LR after resection, the authors only studied patients who did not receive adjuvant radiotherapy.

METHODS

The authors reviewed data from 570 cases involving patients who had undergone resection of a previously untreated single brain metastasis at The University of Texas M. D. Anderson Cancer Center between 1993 and 2006 without receiving postoperative WBRT. All tumors were measured preoperatively on MR images. The resection method (en bloc resection [EBR] or piecemeal resection [PMR]) was noted at the time of surgery. Predictors of LR were assessed using the Cox proportional hazards model.

RESULTS

The median patient age was 58 years, 55% were male, and 88% had a Karnofsky Performance Scale Score > or = 80. The most common primary cancers were those of the lung (28%), skin (melanoma, 21%), kidney (19%), and breast (11%). Piecemeal resection was performed in 201 patients (35%) and EBR in 369 (65%). Local recurrence developed in 84 patients (15%). The histological type of the primary cancer did not significantly predict LR; however, 7 of 22 patients with sarcoma developed LR (p = 0.16). The authors identified 2 variables that increased the risk of LR. Undergoing PMR carried a significantly higher LR risk than EBR (crude hazard ratio [HR] 1.7, 95% CI 1.1-2.6, p = 0.03). Tumors exceeding the median volume (9.7 cm(3)) had a significantly higher LR risk than those that were < 9.7 cm(3) (crude HR 1.7; 95% CI 1.1-2.6; p = 0.02). In the multivariate analysis, small tumors removed by EBR had a significantly lower LR risk.

CONCLUSIONS

The LR risk of a single brain metastasis is influenced by biological factors (such as tumor volume) and treatments (such as the resection method). Early administration of postoperative WBRT may be particularly warranted when such negative tumor-related prognostic factors are noted or when treatment-related ones such as PMR are unavoidable.

Glycomic and transcriptomic response of GSC11 glioblastoma stem cells to STAT3 phosphorylation inhibition and serum-induced differentiation

A glioblastoma stem cell (GSC) line, GSC11, grows as neurospheres in serum-free media supplemented with EGF (epidermal growth factor) and bFGF (basic fibroblast growth factor), and, if implanted in nude mice brains, will recapitulate high-grade glial tumors. Treatment with a STAT3 (signal transducer and activator of transcription 3) phosphorylation inhibitor (WP1193) or 10% FBS (fetal bovine serum) both led to a decrease in expression of the stem cell marker CD133 in GSC11 cells, but differed in phenotype changes. Altered glycolipid profiles were associated with some differentially expressed glycogenes. In serum treated cells, an overall increase in glycosphingolipids may be due to increased expression of ST6GALNAC2, a sialyltransferase. Serum treated cells express more phosphatidylcholine (PC), short chain sphingomyelin (SM) and unsaturated long chain phosphatidylinositol (PI). Decrease of a few glycosphingolipids in the STAT3 phosphorylation inhibited cells may be linked to decreased transcripts of ST6GALNAC2 and UGCGL2, a glucosylceramide synthase. A rare 3-sulfoglucuronylparagloboside carrying HNK1 (human natural killer-1) epitope was found expressed in the GSC11 and the phenotypically differentiated cells. Its up-regulation correlates with increased transcripts of a HNK1 biosynthesis gene, B3GAT2 after serum treatment. Taken together with a quantitative phosphoproteomic study of the same GSC line (C. L. Nilsson, et al. J. Proteome Res. 2010, 9, 430-443), this report represents the most complete systems biology study of cancer stem cell (CSC) differentiation to date. The synergies derived by the combination of glycomic, transcriptomic and phosphoproteomic data may aid our understanding of intracellular and cell-surface events associated with CSC differentiation.

Surgical management of lateral-ventricle metastases: report of 29 cases in a single-institution experience

OBJECT

The aim of this study was to review the outcome of patients undergoing surgery for treatment of lateral-ventricle metastases.

METHODS

Imaging information and chart reviews of operative reports were used to conduct a retrospective analysis in 29 patients who underwent resection of lateral-ventricle metastases at the authors' institution between 1993 and 2007. Clinical and neurosurgical outcomes and recurrence rates were studied.

RESULTS

The mean patient age was 56 years (range 20-69 years); 66% of patients were male. Single intraventricular metastases occurred in 69% of patients, and 55% of them had systemic metastases. The 30-day postoperative mortality rate was 7%. There was intracerebral tumor recurrence in 41% of patients, with 1 patient undergoing a second operation for this. The median postoperative survival duration for 28 patients (excluding 1 patient with preoperative leptomeningeal disease) was 11.7 months; the 3- and 5-year survival rates were 17 and 11%, respectively. Univariate analysis identified factors significantly influencing survival, including the preoperative Karnofsky Performance Scale (KPS) score (p = 0.02), the number of cerebral metastases (p = 0.02), the presence of primary renal cell carcinoma (RCC) (p = 0.02), and the resection method (en bloc vs piecemeal; p = 0.05). The presence of extracranial metastases did not significantly influence survival. Multivariate analysis showed that the preoperative KPS score (p = 0.002), the presence of primary RCC (p = 0.039), and the resection method (en bloc vs piecemeal; p = 0.008) correlated significantly with survival time.

CONCLUSIONS

Surgery is an important component in the management of intraventricular metastases. To the authors' knowledge, this is the first study focusing totally on resection of lateral-ventricle metastases. The authors found that patients with primary RCC, those with a favorable preoperative KPS score, and those who underwent en bloc resection had a better outcome than others.

Abstract 5322: Glioma cancer stem cells induce immune suppressive macrophages

Introduction: The tumor microenvironment can induce monocytes to become immune suppressive macrophages (M2) via the phosphorylation of the signal transducer activator of transcription 3 (STAT3). The M2 cells assume a phenotype with impaired anti-tumor activity, support tumor progression, angiogenesis, and invasion and portend a poor prognosis. Gliomas contain cancer stem cells (gCSCs) that are self-renewing, multipotent, recapitulate the phenotype of the original tumor, and mediate resistance to radiation and chemotherapy. The gCSCs inhibit adaptive immune responses by inhibiting T cell proliferation and effector responses, inducing T cell apoptosis and inducing Tregs secondary to phosphorylated STAT3 (p-STAT3) regulated processes such as secreted TGF-β1 and Galectin-3 and the expression of cell surface molecules such as B7-H1. We therefore hypothesized that gCSCs also exert immune suppression of the innate immune system by inducing M2 cells.

Methods: The gCSCs (n=4) were isolated from surgical glioblastoma specimens. Normal microglia were isolated from brain specimens obtained during resections of extra-axial lesions. Peripheral blood monocytes were isolated from healthy donors and differentiated into macrophages (MDMs), which were then treated with gCSC supernatants and recombinant cytokines. Cell surface markers were assessed by flow cytometry, secreted cytokines measured using ELISA, T cell proliferation by CFSE, Treg induction by flow cytometry and phagocytosis by fluorescent bead uptake. Western blot assays were used to assess activation of the p-STAT1 and p-STAT3 pathways. The p-STAT3 pathway was inhibited with the small molecule WP1066 and siRNA.

Results: The gCSCs produce macrophage inhibitory cytokine (MIC-1) (22.3 - 1056.2 pg/106 cells/24 hours), macrophage inhibitory factor (MIF) (69.1 - 1463.3 pg/106 cells/24 hours), and TGF-β1 (24 - 73.8 pg/106 cells/24 hours) but not IL-23. The MDMs exposed to the gCSC supernatants increased expression of CD80 and B7-H1, and had significantly potentiated secretion of TGF-β1 (106.3 - 3001.8 pg/106 cells/24 hours) and IL-23 (176.8 - 5650.6 pg/106 cells/24 hours). The induced TGF-β1 and IL-23 correlated with inhibition of T cell proliferation and the induction of Tregs. MDM phagocytosis was markedly inhibited by the gCSC supernatants, and physiological amounts of recombinant MIC-1 and MIF. Similar findings were obtained with the human microglia. The gCSC supernatants up-regulated p-STAT3 in the MDMs; however the M2 phenotype could be reversed when p-STAT3 was blocked in either the gCSCs or the MDMs.

Conclusions: The gCSCs secrete factors such as MIC-1 and MIF that can induce immune suppression in macrophages characterized by altered expression of cell surface markers, increased secretion of TGF-β1 and IL-23 with the associated ability to inhibit T cell proliferation and induce Tregs, and impaired phagocytosis. The M2 phenotype is reversed with p-STAT3 blockade.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5322.

Abstract 4305: Refinement of the glioma cancer stem cell marker profile

Infiltrating gliomas are the most frequently occurring adult brain tumor and, among high-grade forms, typically result in poor patient survival. These tumors tend to be refractory to most treatments, including aggressive surgical resection and chemoradiation. This treatment resistance is hypothesized to be the result of a small population of cells within the tumor which are responsible for tumor initiation, called glioma cancer stem cells (GCSCs). As is true in other stem cell systems, such as hematopoiesis, multiple cell-surface protein markers are needed to accurately define the true stem cell population. We and others have previously identified the glycoprotein podoplanin (pdpn) as a marker of GCSC, which improves upon the established marker, CD133. To refine the GCSC marker profile beyond these two proteins, we examined a number of candidate markers in combination with pdpn that have been proposed as stem cell markers in gliomas or other tumors or tissues. Candidate markers were analyzed by flow cytometry using primary glioma cell lines maintained as neurosphere cultures and fresh tumor specimens. Markers identifying a unique cell population either alone or in combination with pdpn were further analyzed by in vitro neurosphere formation assay and clonogenic survival assay following 2 Gy ionizing radiation. Candidates showing enrichment for stem cells based on these assays were examine for in vivo tumor initiation using flow sorted subpopulations of cells with and without the expression of the candidate protein. As expression of putative stem cell markers will likely predict for poor patient survival, candidate markers were also examined in human tumors by immunohistochemsitry. Among the most promosing candidates were CD97, CXCR4, CD58 and CD44. Flow cytometry revealed CD97 expression in 75%, CD58 in 80%, CXCR4 in 100%, and CD44 in 100% of tumors examined to date. Examination of primary neurosphere cultures, found CD97 in 80%, CXCR4 in 83%, CD58 in 100%, and CD44 in 100% of lines examined. Both CD44+ and CD58+ cells exhibited increased neurophere formation rates and in vivo tumor initiation. These stem-like characteristics were enhanced in those subpopulations also expressing pdpn. RNAs collected from these subpopulations were used for expression profiling to determine if these subpopulation express a unique gene expression. Results thus far indicate that pdpn expression is needed for the stem-like phenotype and that this is enhanced in populations co-expressing CD44, CD15, and/or CD58. Further refinement of this profile will aide in the isolation of the “true” GCSC and allow for improved therapeutic targeting of these resistant cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4305.