Assessing CpG island methylator phenotype, 1p/19q codeletion, and MGMT promoter methylation from epigenome-wide data in the biomarker cohort of the NOA-04 trial

BACKGROUND

Molecular biomarkers including isocitrate dehydrogenase 1 or 2 (IDH1/2) mutation, 1p/19q codeletion, and O(6)-methylguanine-DNA-methyltransferase (MGMT) promoter methylation may improve prognostication and guide treatment decisions for patients with World Health Organization (WHO) anaplastic gliomas. At present, each marker is individually tested by distinct assays. Illumina Infinium HumanMethylation450 BeadChip arrays (HM450) enable the determination of large-scale methylation profiles and genome-wide DNA copy number changes. Algorithms have been developed to detect the glioma CpG island methylator phenotype (G-CIMP) associated with IDH1/2 mutation, 1p/19q codeletion, and MGMT promoter methylation using a single assay.

METHODS

Here, we retrospectively investigated the diagnostic and prognostic performance of these algorithms in comparison to individual marker testing and patient outcome in the biomarker cohort (n = 115 patients) of the NOA-04 trial.

RESULTS

Concordance for IDH and 1p/19q status was very high: In 92% of samples, the HM450 and reference data agreed. In discordant samples, survival analysis by Kaplan-Meier and Cox regression analyses suggested a more accurate assessment of biological phenotype by the HM450 analysis. The HM450-derived MGMT-STP27 model to calculate MGMT promoter methylation probability revealed this aberration in a significantly higher fraction of samples than conventional methylation-specific PCR, with 87 of 91 G-CIMP tumors predicted as MGMT promoter-methylated. Pyrosequencing of discordant samples confirmed the HM450 assessment in 14 of 17 cases.

CONCLUSIONS

G-CIMP and 1p/19q codeletion are reliably detectable by HM450 analysis and are associated with prognosis in the NOA-04 trial. For MGMT, HM450 suggests promoter methylation in the vast majority of G-CIMP tumors, which is supported by pyrosequencing.

Comparing the expression of integrins αvβ3, αvβ5, αvβ6, αvβ8, fibronectin and fibrinogen in human brain metastases and their corresponding primary tumors

AIMS

To evaluate the expression of αv-series integrins in brain metastases. Inhibitors targeting these integrins are being tested for their therapeutic potential.

MATERIAL AND METHOD

The extracellular regions of the αvβ3, αvβ5, αvβ6, αvβ8, the cytoplasmic domain of β3, the αv-chain, and the ECM molecules fibronectin and fibrinogen were studied immunohistochemically in a series of 122 carcinoma and 60 melanomas metastatic to the central nervous system. In addition, 38 matched primary and metastatic tumors to the brain were compared directly.

RESULTS

The αv-subunit was generally moderately to highly expressed in most tumors. αvβ3 and cytoplasmic β3 were weakly to moderately detectable in metastatic renal cell carcinomas and melanomas, αvβ5 was prominently expressed in metastatic renal and colorectal carcinomas, αvβ6 was most abundantly detectable in metastatic lung adenocarcinomas, but absent in melanomas. The tumor associated vessels in CNS metastases consistently expressed αvβ3, αvβ5, αv-, fibronectin and fibrinogen, however, mostly at low levels, while αvβ6, αvβ8 were lacking in vasculature. The comparative analysis of 38 matched primary tumors and brain metastases showed comparable levels of expression only for αvβ3 and αvβ8, while αvβ6 and αvβ5 were higher in primaries.

CONCLUSION

We confirmed that integrin expression exhibits considerable heterogeneity according to tumor origin. αvβ5 is the most promising target for integrin targeted treatment in brain metastases.

Expression of integrins αvβ3 and αvβ5 and their ligands in primary and secondary central nervous system neoplasms

AIMS

To study the expression of integrins αvβ3 and αvβ5 and their ligands in tumour, stroma and endothelial cells from human glioblastoma and CNS metastases from breast, lung and skin tumours.

METHODS AND RESULTS

Integrin and integrin ligand expression was quantified in frozen tumour surgical specimens (15 glioblastomas and breast carcinoma metastases as well as 16 lung carcinoma and melanoma metastases) using immunohistochemistry. Gene expression profiles were evaluated in glioblastomas (n=424) and in normal brain (n=11). Overall, αvβ3 expression was more common than αvβ5 except in tumours derived from lung. αvβ3 expression was most frequent in glioblastomas and melanoma metastases. Most lung-derived tumours expressed αvβ5 but expression was less frequent in other tumours; about 20% of breast-derived tumours strongly expressed αvβ5. Melanoma-derived tumours did not express αvβ5. Expression of integrin ligands vitronectin, fibrinogen, fibronectin and osteopontin was variable between tumours, although most tumours expressed the ligands to some extent. Marked αvβ3, but not αvβ5, expression was common in stroma of CNS metastases. In blood vessels, αvβ3 expression was more frequent than αvβ5 and more pronounced in CNS metastases than in glioblastomas. Integrin ligand expression occurred in blood vessels in most tumours. In glioblastomas, mRNA expression of αvβ3, αvβ5, osteopontin and fibronectin were significantly upregulated over normal brain.

CONCLUSIONS

Overall, we report distinct and heterogeneous patterns of integrin expression in primary and secondary brain tumours that may be relevant to the future development of integrin-targeting therapeutic approaches to brain tumours.

Activated leukocyte cell adhesion molecule is expressed in neuroepithelial neoplasms and decreases with tumor malignancy, matrix metalloproteinase 2 expression, and absence of IDH1R132H mutation

Diffuse growth of gliomas is based on enhanced cell migration and remodeling of the extracellular matrix. Up-regulation of matrix metalloproteinases in gliomas is associated with a poor prognosis. The activated leukocyte adhesion molecule is considered to be indispensable for conversion of matrix metalloproteinase 2 into its active form. We therefore investigated the expression of activated leukocyte adhesion molecule in 9 malignant glial cell lines, 105 normal/reactive human brain specimens, 248 astrocytomas/glioblastomas, 98 ependymomas, 35 oligodendrogliomas, 10 neurocytomas, 10 primitive neuroectodermal tumors (PNET), and 36 medulloblastomas by immunohistochemistry and in selected cases by reverse transcriptase polymerase chain reaction. Correlation between activated leukocyte adhesion molecule expression and tumor grades and entities, proliferation activity, matrix metalloproteinase 2 expression, prognostic isocitrate dehydrogenase (IDH)1 mutation (R132H) status, O-6-methylguanine DNA-methyltransferase (MGMT) promoter status, or association with patient survival were analyzed. All oligodendrogliomas were strongly activated leukocyte adhesion molecule positive. Numbers of activated leukocyte adhesion molecule positive tumors were higher in glioblastomas (93%) than in diffuse astrocytomas (83%), but mean expression intensity was significantly reduced. Anaplastic ependymomas (68%) exhibited reduced numbers of activated leukocyte adhesion molecule-positive tumors and staining intensity compared with lower-grade ependymomas (85%). Activated leukocyte adhesion molecule expression in gliomas was independent of proliferative activity, MGMT status, patient survival, and age, whereas gliomas with IDH1 (R132H) mutation had significantly higher activated leukocyte adhesion molecule levels than their wild-type counterparts. Matrix metalloproteinase 2-negative glioblastomas exhibited significantly reduced activated leukocyte adhesion molecule expression levels compared with astrocytomas. In summary, our findings indicate that activated leukocyte adhesion molecule expression levels in gliomas are probably linked to other mechanisms than its supposed role as regulator of matrix metalloproteinase 2.

De novo expression of the hemoglobin scavenger receptor CD163 by activated microglia is not associated with hemorrhages in human brain lesions

The main function of CD163 (hemoglobin scavenger receptor) is to bind the hemoglobin-haptoglobin complex, thereby mediating extravasal hemolysis. However, CD163 also has an antiinflammatory function. After CD163-mediated endocytosis, hemoglobin is catabolized further by hemeoxygenase 1 (HO-1). Previously, we found expression of HO-1 to be restricted to microglia/macrophages at sites of hemorrhages in human traumatic and ischemic brain lesions. We now investigated if CD163 expression is also correlated with hemorrhages in brain lesions. Methods. Autopsy brain tissue from 44 cases with hemorrhagic brain lesions (32 traumatic brain injuries/TBI, 12 intracerebral bleedings/ICB), 56 non-hemorrhagic brain lesions (30 ischemias, 26 hypoxias) and 6 control brains were investigated. The post injury survival times ranged from a few minutes to 60 months. Results. In controls, single perivascular monocytes expressed CD163, but only single CD163+ microglia were found in 3/6 cases. CD163+ cells in the parenchyma (activated microglia/macrophages) increased significantly within 24 hours after trauma and ischemia and within 1-7 days following ICB or hypoxia. Overall, significantly lower and higher levels of parenchymal CD163+ cells occurred in hypoxia and ischemia, respectively. Perivascular CD163+ cells also increased significantly in all pathological conditions. In areas remote from circumscribed brain lesions (TBI, ICB, ischemia), significant changes were only found in ICB and ischemia. Conclusions. De novo expression of CD163 by activated microglia/macrophages and CD163+ infiltrating monocytes are neither restricted to nor predominant in hemorrhagic brain lesions. Thus, the antiinflammatory function of CD163 probably predominates, both in hemorrhagic and non-hemorrhagic brain lesions and points to possible immunomodulatory treatment strategies targeting CD163.

Spatio-temporal deleted in colorectal cancer (DCC) and netrin-1 expression in human foetal brain development

AIMS

Deleted in colorectal cancer (DCC) and its ligand netrin-1 are known as axonal guidance factors, being involved in angiogenesis, migration and survival of precursor cells in the embryonic mammalian central nervous system (CNS). So far, little is known about the distribution of those molecules in human CNS development.

METHODS

We investigated 22 human foetal brain specimens (12th and 28th week of gestation) for DCC and netrin-1 expression by means of immunohistochemistry, immunofluorescence and confocal laser microscopy. Statistical analysis was performed by applying a semi-quantitative score, including staining intensity and frequency and correlation with foetal age.

RESULTS

DCC and netrin-1 were differentially expressed throughout the developing human foetal telencephalic and cerebellar cortical layers. Netrin-1 exhibited the highest levels in telencephalic germinal layers, whereas the strongest DCC immunoreactivity was seen in the developing cortical plate. Netrin-1 and DCC were predominantly present on cerebellar external granule layer cells. Distinct co-expression was seen in maturing foetal brainstem nuclei, cerebellar external granular layer and the choroid plexus. In contrast, endothelial cells showed strong netrin-1 expression with subsidiary DCC immunoreactivity. Pontine and telencephalic axonal fibre tracts also demonstrated strong netrin-1 expression.

CONCLUSIONS

We show that DCC and netrin-1 are ubiquitously expressed in the human foetal brain; however, both exhibit a distinct spatio-temporal expression pattern. Together with the data from animal experiments, our findings might indicate also an important role for DCC and netrin-1 in human foetal CNS development.

Immune surveillance of the normal human CNS takes place in dependence of the locoregional blood-brain barrier configuration and is mainly performed by CD3(+)/CD8(+) lymphocytes

Despite the blood-brain barrier (BBB) the human CNS is continuously screened by blood-derived immunological cells. In certain brain areas the local BBB configuration grants passage of large molecules, whereas others are better shielded. We investigated whether these regional BBB compositions are paralleled by differences in the degree of cellular immunosurveillance by investigating tissue from 23 normal human brains for several CD markers, FoxP3, granzyme B, and perforin. Our results provide evidence that immunosurveillance is associated with locoregional BBB configuration and is mainly performed by CD3(+)/CD8(+)/granzyme B(-)/perforin(-) lymphocytes.

Pituitary adenomas and craniopharyngiomas are CDX2 negative neoplasms

OBJECTIVES

Previous studies have shown an inverse correlation between the expression of CDX2 (also known as CDX3) and tumour grade, stage and lymph node dissemination in colorectal adenomas and adenocarcinomas. Although less frequent, expression of CDX2 has also been reported in various other epithelial tissues and carcinomas. While many neoplasms have been studied, to date, no data is available on CDX2 expression in craniopharyngiomas. Furthermore, only very few data are available on CDX2 expression in normal pituitary gland tissue and/or pituitary adenomas.

MATERIAL AND METHODS

We investigated CDX2 expression in 28 normal pituitary glands, 75 pituitary adenomas of varying hormonal activity (including 7 invasive adenomas and 7 atypical adenomas) and 23 craniopharyngiomas (17 adamantinous and 6 papillary) in tissue microarrays.

RESULTS

None of the pituitary adenomas, craniopharyngiomas and normal pituitary glands showed expression of CDX2.

CONCLUSIONS

There is no evidence for that CDX2 might play a role in tumourigenesis, invasive growth or tumour recurrence of pituitary adenomas or in tumourigenesis of craniopharyngiomas. But, presence of CDX2 expression might be useful in distinguishing intrasellar metastases from primary tumours of the sellar region.

NOA-04 randomized phase III trial of sequential radiochemotherapy of anaplastic glioma with procarbazine, lomustine, and vincristine or temozolomide

PURPOSE

The standard of care for anaplastic gliomas is surgery followed by radiotherapy. The NOA-04 phase III trial compared efficacy and safety of radiotherapy followed by chemotherapy at progression with the reverse sequence in patients with newly diagnosed anaplastic gliomas.

PATIENTS AND METHODS

Patients (N = 318) were randomly assigned 2:1:1 (A:B1:B2) to receive conventional radiotherapy (arm A); procarbazine, lomustine (CCNU), and vincristine (PCV; arm B1); or temozolomide (arm B2) at diagnosis. At occurrence of unacceptable toxicity or disease progression, patients in arm A were treated with PCV or temozolomide (1:1 random assignment), whereas patients in arms B1 or B2 received radiotherapy. The primary end point was time to treatment failure (TTF), defined as progression after radiotherapy and one chemotherapy in either sequence.

RESULTS

Patient characteristics in the intention-to-treat population (n = 274) were balanced between arms. All histologic diagnoses were centrally confirmed. Median TTF (hazard ratio [HR] = 1.2; 95% CI, 0.8 to 1.8), progression-free survival (PFS; HR = 1.0; 95% CI, 0.7 to 1.3, and overall survival (HR = 1.2; 95% CI, 0.8 to 1.9) were similar for arms A and B1/B2. Extent of resection was an important prognosticator. Anaplastic oligodendrogliomas and oligoastrocytomas share the same, better prognosis than anaplastic astrocytomas. Hypermethylation of the O(6)-methylguanine DNA-methyltransferase (MGMT) promoter (HR = 0.59; 95% CI, 0.36 to 1.0), mutations of the isocitrate dehydrogenase (IDH1) gene (HR = 0.48; 95% CI, 0.29 to 0.77), and oligodendroglial histology (HR = 0.33; 95% CI, 0.2 to 0.55) reduced the risk of progression. Hypermethylation of the MGMT promoter was associated with prolonged PFS in the chemotherapy and radiotherapy arm.

CONCLUSION

Initial radiotherapy or chemotherapy achieved comparable results in patients with anaplastic gliomas. IDH1 mutations are a novel positive prognostic factor in anaplastic gliomas, with a favorable impact stronger than that of 1p/19q codeletion or MGMT promoter methylation.

Chemoradiotherapy of newly diagnosed glioblastoma with intensified temozolomide

PURPOSE

To evaluate the toxicity and efficacy of chemoradiotherapy with temozolomide (TMZ) administered in an intensified 1-week on/1-week off schedule plus indomethacin in patients with newly diagnosed glioblastoma.

PATIENTS AND METHODS

A total of 41 adult patients (median Karnofsky performance status, 90%; median age, 56 years) were treated with preirradiation TMZ at 150 mg/m(2) (1 week on/1 week off), involved-field radiotherapy combined with concomitant low-dose TMZ (50 mg/m(2)), maintenance TMZ starting at 150 mg/m(2) using a 1-week on/1-week off schedule, plus maintenance indomethacin (25 mg twice daily).

RESULTS

The median follow-up interval was 21.7 months. Grade 4 hematologic toxicity was observed in 15 patients (36.6%). Treatment-related nonhematologic Grade 4-5 toxicity was reported for 2 patients (4.9%). The median progression-free survival was 7.6 months (95% confidence interval, 6.2-10.4). The 1-year survival rate was 73.2% (95% confidence interval, 56.8-84.2%). The presence of O(6)-methylguanine-DNA methyltransferase (MGMT) gene promoter methylation in the tumor tissue was associated with significantly superior progression-free survival.

CONCLUSION

The dose-dense regimen of TMZ administered in a 1-week on/1-week off schedule resulted in acceptable nonhematologic toxicity. Compared with data from the European Organization for Research and Treatment of Cancer/National Cancer Institute of Canada trial 26981-22981/CE.3, patients with an unmethylated MGMT gene promoter appeared not to benefit from intensifying the TMZ schedule regarding the median progression-free survival and overall survival. In contrast, data are promising for patients with a methylated MGMT promoter.

Immunohistochemical analysis of CDX2 expression in normal choroid plexus epithelium and choroid plexus tumors

BACKGROUND

The Wnt and BMP signaling pathways are involved in the morphogenesis of both gastrointestinal and choroid plexus epithelium. In the intestine, Wnt signaling represses the expression of the tumor suppressor gene CDX2 via SOX9, a transcription factor, which is also expressed in the choroid plexus. Recently, an inverse correlation between CDX2 expression and tumor grade, tumor stage and lymph node metastasis in colorectal adenocarcinomas has been reported. Besides intestinal tissues, expression of CDX2 has also been reported in various other epithelial tissues and carcinomas. To date, no data exist on expression of CDX2 in normal and neoplastic choroid plexus epithelium.

AIM

To investigate CDX2 expression in normal and neoplastic choroid plexus.

MATERIALS AND METHODS

Paraffin-embedded samples from 60 normal choroid plexus, including 23 fetal tissue samples and from 65 choroid plexus tumors (47 choroid plexus papillomas WHO grade I, 16 atypical choroid plexus papillomas and 2 choroid plexus carcinomas WHO grade III) were examined by immunohistochemistry. Samples from normal choroid plexus were collected from 45 autopsy cases and from 15 neurosurgical specimens.

RESULTS

Normal and neoplastic choroid plexus lacked CDX2 expression.

CONCLUSION

In our series, immunohistochemistry shows no evidence for a role of CDX2 in development or differentiation of normal choroid plexus from the 9th gestational week until adulthood. Since choroid plexus tumors reliably lack CDX2 immunoreactivity, this marker may be helpful in distinguishing cerebral metastases from CDX2-positive adenocarcinomas and choroid plexus neoplasms.

Modulation of TGF-beta activity by latent TGF-beta-binding protein 1 in human malignant glioma cells

High biological activity of the transforming growth factor (TGF)-beta-Smad pathway characterizes the malignant phenotype of malignant gliomas and confers poor prognosis to glioma patients. Accordingly, TGF-beta has become a novel target for the experimental treatment of these tumors. TGF-beta is processed by furin-like proteases (FLP) and secreted from cells in a latent complex with its processed propeptide, the latency-associated peptide (LAP). Latent TGF-beta-binding protein 1 (LTBP-1) covalently binds to this small latent TGF-beta complex (SLC) and regulates its function, presumably via interaction with the extracellular matrix (ECM). We report here that the levels of LTBP-1 protein in vivo increase with the grade of malignancy in gliomas. LTBP-1 is associated with the ECM as well as secreted into the medium in cultured malignant glioma cells. The release of LTBP-1 into the medium is decreased by the inhibition of FLP activity. Gene-transfer mediated overexpression of LTBP-1 in glioma cell lines results in an increase inTGF-beta activity. Accordingly, Smad2 phosphorylation as an intracellular marker of TGF-beta activity is enhanced. Conversely, LTBP-1 gene silencing reduces TGF-beta activity and Smad2 phosphorylation without affecting TGF-beta protein levels. Collectively, we identify LTBP-1 as an important modulator of TGF-beta activation in glioma cells, which may contribute to the malignant phenotype of these tumors.

Concepts and developments in peripheral nerve surgery

Nerve injuries may result in sensory and motor deficits when not treated appropriately. Especially the surgical management of nerve defects still represents a challenge for the surgeon. In these cases the grafting of autologous nerves represents the only reasonable approach. Due to the side effects associated with this method (sacrifice of donor nerves, neuroma formation in the harvesting area, limited availability of donor nerves, etc.), numerous alternatives were proposed in order to avoid the transplantation of autologous tissue. This review provides a general view on the state of the art of how to supply gaping injuries in the peripheral nerve. Furthermore new approaches emphasizing tubulization techniques for the reconstruction of lost nerve tissue are described with a special focus on various materials with their advantages and disadvantages.

Expression of EAAT-1 distinguishes choroid plexus tumors from normal and reactive choroid plexus epithelium

Microscopic distinction of normal choroid plexus (CP) from choroid plexus tumors (CPT) may be difficult, especially in small samples of well-differentiated CP papillomas. So far, there are no established markers that reliably distinguish normal and neoplastic CP epithelium. Recently, a correlation between expression/function of glial glutamate transporters EAAT-1 (GLAST) and EAAT-2 (Glt-1) and tumor proliferation has been reported. Furthermore, we previously found that CPTs frequently express EAAT-1, but not EAAT-2. We now compared expression of EAAT-1, EAAT-2 and GFAP in non-neoplastic CP (n = 68) and CPT (n = 79) by immunohistochemistry. Tissue of normal CP was obtained from 50 autopsy cases (20 normal and 30 pathologic brains) and 18 neurosurgical specimens that included 17 fetal, 21 pediatric and 30 adult cases. In non-neoplastic postnatal CP (n = 51), focal expression of EAAT-1 was found in only two pediatric cases (4%). In CPT, expression of EAAT-1 was found in 64 of 79 (81%) tumor samples and was significantly age-dependent (P < 0.0001). Hence, EAAT-1 expression distinguishes neoplastic from normal CP, both in children (P = 0.0032) and in adults (P < 0.0001). Immunostaining for EAAT-2 in selected samples from cases of different ages showed that normal CP (n = 15) or CPT (n = 16) lacked EAAT-2 expression. GFAP expression was found in 3 of 32 (10%) normal CP and in 28 of 73 (38%) tumor samples. In conclusion, in contrast to neoplastic CP samples, expression of EAAT-1 is exceptionally rare in non-neoplastic CP. Thus, EAAT-1 is superior to GFAP as a helpful diagnostic tool in CP samples.

Erythropoietin receptor is expressed in meningiomas and lower levels are associated with tumour recurrence

AIMS

The Epo-EpoR pathway plays a role in tumour growth, metastasis and treatment resistance and is a potential target in oncological treatment. As the EpoR status in human meningiomas is unknown, our aim was to characterize EpoR expression in these tumours.

METHODS

We examined 131 meningioma samples of all WHO grades from 116 patients by immunohistochemistry for EpoR. Among these, 25 meningiomas showed brain invasion and 29 patients had a further tumour recurrence. A group of 20 patients without tumour recurrence served as controls. In 12 cases we were able to compare both the primary and the following recurrent tumours. The presence of EpoR in meningiomas was confirmed by RT-PCR and Western blot.

RESULTS

EpoR was expressed in all meningiomas. Statistical analysis revealed that the mean expression levels of EpoR were significantly lower in primary tumours with known recurrence compared with a recurrence-free control group. Additional matched pair analysis in individual cases showed no significant differences between primary and recurrent tumours. No significant correlation between EpoR expression and WHO grade, age, sex or brain invasion was detected. Using specific primer pairs for RT-PCR, we were able to detect all three known isoforms of EpoR: the full-length isoform EpoR-F, the truncated isoform EpoR-T and the soluble isoform EpoR-S.

CONCLUSIONS

Our results demonstrate the expression of EpoR in meningiomas. Lower EpoR mean levels might be a useful marker for a higher recurrence risk, but further studies are needed to clarify the influence of EpoR on recurrences and the role of the different isoforms.

No evidence for WT1 involvement in a beta-catenin-independent activation of the Wnt signaling pathway in pituitary adenomas

The overexpression of Wilms' tumor gene product WT1, which acts as a tumor suppressor or oncogene, has been reported in various malignancies. Recent studies have shown that the interaction partner Wnt-4 is upregulated in pituitary adenomas dependent on the Pit-1 lineage (somatotrophs, lactotrophs, and thyrotrophs). However, no data on WT1 expression in nontumorous pituitary tissue or pituitary adenomas is available to date. We investigated WT1 expression in 90 paraffin-embedded pituitary adenomas, including eight atypical adenomas, and in 28 nontumorous pituitary glands by immunohistochemistry. WT1 is absent in epithelial cells of all nontumorous pituitary glands and in 87 out of 90 pituitary adenomas. Only two GHomas (including one atypical adenoma) and one gonadotropin-producing adenoma expressed WT1 in the cytoplasm of single tumor cells without nuclear staining. There is no evidence that WT1 does regulate the Wnt-4/beta-catenin-independent pathway which is activated in the Pit-1-expressing subset of pituitary adenomas.

Holocord pilocytic astrocytoma--case report and review of the literature

Intramedullary glial neoplasms affecting the entire cord from the cervicomedullary junction to the conus are termed "holocord tumors" and those diagnosed as pilocytic astrocytoma are rare. Herein, we present a 13-year-old girl with a tumor extending from the cervicomedullary junction to the conus which was partially resected in a four-stage approach. Histopathological examination of all specimens resulted in diagnosis of a pilocytic astrocytoma. Although no signs of atypia were present, an elevated proliferative activity of endothelial vessels was noted. Residual parts of the tumor showed progress making additional surgery necessary. Therapy and its consequences are discussed and an overview of the literature of these rare longitudinally extensive intramedullary lesions is given.

Mature cerebellar teratoma in adulthood

Extragonadal teratomas in adulthood are exceptionally rare and usually not located within the cerebellum. We here report on a 66-year-old male patient clinically presenting with chronic occipital headache and episodes of severe vertigo. Neuroradiological investigations revealed a hemorrhagic tumor mass in the cerebellar vermis which was surgically removed and histologically diagnosed as mature teratoma. Hence, the presented case is extraordinary with regard to age, late clinical onset of symptoms and cerebellar location. Late clinical manifestation of the tumor in this case is probably due to an acute late-onset hemorrhage within the tumor.

EGR-1 is regulated by N-methyl-D-aspartate-receptor stimulation and associated with patient survival in human high grade astrocytomas

Early growth response-1 (EGR-1) is considered a central regulator in tumor cell proliferation, migration and angiogenesis and a promising candidate for gene therapy in human astrocytomas. However, conflicting data have been reported suggesting that both tumor promoting and anti-tumor activity of EGR-1 and its regulation, expression and prognostic significance still remain enigmatic. Our study explored EGR-1 expression and regulation in astrocytomas and its association with patient survival. As we detected two EGR-1 mRNA variants, one containing a N-methyl-D-aspartate-receptor (NMDA-R) responsive cytoplasmic polyadenylation element (CPE), further experiments were performed to determine the functional role of this pathway. After NMDA stimulation of SV-FHAS and neoplastic astrocytes, real-time polymerase chain reaction showed an increase of the CPE, containing EGR-1 splice variant only in astrocytoma cells. The surface expression and functionality of NMDA-R were demonstrated by flow cytometric analysis and measurement of increased intracellular Ca(2+). EGR-1 was mainly restricted to tumor cells expressing NMDA-R and significantly up-regulated in astrocytic tumors compared with normal brain. Further, EGR-1 expression was significantly (P < 0.007) associated with enhanced patient survival and was an independent prognostic factor in multivariate analysis in high grade astrocytomas. The NMDA-R-mediated EGR-1 expression, therefore, seems to be a promising target for novel clinical approaches to astrocytoma treatment.

Diagnostic value of WT1 in neuroepithelial tumours

AIMS

Currently, clinical trials using WT1 (Wilms tumour gene) peptide vaccines are conducted in haematopoietic malignancies and solid cancers. Single reports showed that the Wilms tumour gene product WT1 is also expressed in astrocytic neoplasms. Our aim was to investigate WT1 expression in a large cohort of various neuroepithelial tumours of different World Health Organization (WHO) grades and in normal central nervous system (CNS) tissue specimens to test its potential value as a diagnostic marker.

METHODS

Specimens were assessed by RT-PCR, Western blotting and immunohistochemistry. The samples investigated in our study consisted of 334 human neuroepithelial tumours, among those 33 oligodendrogliomas, 219 astrocytomas (including 105 glioblastomas) and 47 ependymomas.

RESULTS

Our results showed a de novo WT1 expression in neuroepithelial tumours. In diffuse astrocytomas and ependymomas, WT1 expression increased significantly with the grade of malignancy. In contrast, no significant difference was seen between WHO grade-II and -III oligodendrogliomas. Controlling for WHO grade, the comparison of oligodendrogliomas with ependymal and astrocytic tumours showed higher expression values for the latter.

CONCLUSIONS

Our study shows that WT1 is expressed de novo in numerous neuroepithelial tumours and increases with the grade of malignancy. These results suggest an important role of WT1 in tumourigenesis and progression in human brain tumours.

WT1 expression distinguishes astrocytic tumor cells from normal and reactive astrocytes

Particularly in small brain biopsies, it might be difficult to distinguish reactive astrogliosis from low-grade or infiltration zones of high-grade astrocytomas. So far no immunohistochemical marker allows a reliable distinction. Recently, the over-expression of Wilms' tumor gene product WT1 was reported in astrocytic tumor cells. However, no sufficient data on WT1 expression in normal or reactive astrocytes are available. Therefore, we investigated WT1 expression in paraffin-embedded brain sections from 28 controls, 48 cases with astrogliosis of various etiology and 219 astrocytomas [World Health Organization (WHO) grades I-IV] by immunohistochemistry. In normal brains and in astrogliosis, expression of WT1 was restricted to endothelial cells. In astrocytomas, WT1-positive tumor cells were found in pilocytic astrocytomas (66.7% of cases), diffuse astrocytomas (52.7%) WHO grade II (52.7%), anaplastic astrocytomas (83.4%) and glioblastomas (98.1%). Overall, the majority of all astrocytic neoplasms (84.5%) expressed WT1. Establishing a cut-off value of 0% immunoreactive tumor cells served to recognize neoplastic astrocytes with 100% specificity and 68% sensitivity and was associated with positive and negative predictive values of 1 and 0.68, respectively. Therefore, WT1 expression in astrocytes indicates a neoplastic origin and might represent an important diagnostic tool to differentiate reactive from neoplastic astrocytes by immunohistochemistry.

Pitfalls in the assessment of MGMT expression and in its correlation with survival in diffuse astrocytomas: proposal of a feasible immunohistochemical approach

Immunohistochemical studies showed that O(6)-methylguanine-DNA methyltransferase (MGMT) protein expression is negatively associated with survival in glioblastomas treated with alkylating agents in accordance with previous results of methylation-specific PCR. Implementation of this data in routine clinical diagnostics is limited due to often inappropriate study designs, e.g. pooling of tumor entities, WHO grades or primary and secondary glioblastomas, disregard concerning the infiltration zone or various epidemiological factors. The aim of our study was to evaluate MGMT expression and its prognostic value taking into consideration the aforementioned deficiencies. For this, 162 astrocytic tumors WHO II-IV (36 diffuse astrocytomas WHO II, 51 anaplastic astrocytomas, 75 primary glioblastomas) as well as 25 glioblastoma infiltration zones and 19 glioblastoma relapses were analyzed for immunohistochemical MGMT protein expression using tissue microarray technique. Expression of MGMT significantly decreased from WHO grade II (25.6%) to glioblastoma (16.8%, p = 0.01) with lowest levels in grade III tumors (10.2%, II/III p < 0.0001). Significant negative associations of MGMT and survival were detected for WHO grade II and IV (p = 0.003 and 0.013). The optimal cut-off value of MGMT positive nuclei in primary glioblastomas discriminating patients with significantly different survival rates was at 15% (Log-Rank p = 0.0002). Individual relapse tumors showed changes of MGMT expression to a varying degree. The infiltration zone demonstrated a significant increase of MGMT (p < 0.0001). We conclude that immunohistochemical MGMT assessment has potential as a powerful diagnostic tool but analysis should only be performed in a grade dependent manner, before radio-/chemotherapy and with special attention to the infiltration zone of diffuse astrocytomas.

Atypical type II silent corticotrophic adenoma developing into Cushing's disease upon second recurrence

Herein, we report the case of a 73-year old male patient who presented with two recurrences of a pituitary adenoma within a period of 15 years. The first tumor resection 15 years ago revealed a non-functioning pituitary macroadenoma. 11 years later, the first recurrence of the tumor was reoperated. Throughout the early course of the disease, he suffered from secondary adrenal insufficiency and required replacement therapy with hydrocortisone. Currently, he presented with the second recurrence and clinical examination revealed signs of Cushing's disease. This was clearly confirmed by endocrinological evaluation. A retrospective analysis of all histological and immunohistochemical slides rendered an adenoma exhibiting chromophobia, ACTH-positivity and features of atypia such as elevated p53 and Ki67 expression as well as nuclear polymorphism. According to the revised WHO classification it was classified as atypical type II silent corticotroph adenoma at the time of the first and second surgery. The specimen removed during the recent surgery displayed the same histological features and was classified as corticotroph adenoma. The combination of an atypical type II adenoma and the switch in the hormone status to an endocrinologically active adenoma makes this case exceedingly rare.

Severe hypoxia and multiple infarctions resembling Creutzfeldt-Jakob disease

Although neuropathological examination is still required for the definite diagnosis of Creutzfeldt-Jakob disease (CJD), specialised clinical assessment predicts probable CJD. Here we present a 73-year-old female patient presenting with rapid cognitive decline, visual, acoustic and cerebellar disturbances, ataxia and EEG changes compatible with early CJD stages. MRI revealed hyperintensities within the thalami, hypothalami, corpora mammillaria, the tectum and the cortex. Initial neuropathological examination showed severe cortical and subcortical spongiosis. However, both immunohistochemistry and Western blotting showed no pathological prion protein. Finally, small infarctions affecting the tectum, tegmentum, corpora mammillaria and global hypoxic-ischaemic changes could be identified as the probable reason for the changes interpreted as CJD-related pathology. Hypoxic-ischaemic CNS alterations mainly affecting the supply area of the basilar artery should be ruled out in case of probable CJD. In addition, severe spongiosis can be misleading in the histological examination, suggesting the diagnosis of a prion-induced spongiform encephalopathy.

Two functionally linked amino acids in the stem 2 region of measles virus haemagglutinin determine infectivity and virulence in the rodent central nervous system

Rodent brain-adapted measles virus (MV) strains, such as CAM/RB and recombinant MVs based on the Edmonston strain containing the haemagglutinin (H) of CAM/RB, cause acute encephalitis after intracerebral infection of newborn rodents. We have demonstrated that rodent neurovirulence is modulated by two mutations at amino acid positions 195 and 200 in the H protein, one of these positions (200) being a potential glycosylation site. In order to analyse the effects of specific amino acids at these positions, we introduced a range of individual and combined mutations into the open reading frame of the H gene to generate a number of eukaryotic expression plasmids. The functionality of the mutant H proteins was assessed in transfected cells and by generating recombinant viruses. Interestingly, viruses caused acute encephalitis only if the amino acid Ser at position 200 was coupled with Gly at position 195, whereas viruses with single or combined mutations at these positions, including glycosylation at position 200, were attenuated. Neurovirulence was associated with virus spread and induction of neuronal apoptosis, whereas attenuated viruses failed to infect brain cells. Similar results were obtained by using primary brain-cell cultures. Our findings indicate that a structural alteration in the stem 2 region of the H protein at position 195 or 200 interferes with infectivity of rodent neurons, and suggest that the interaction of the viral attachment protein with cellular receptors on neurons is affected.

Cavernoma of the trochlear nerve

Here we present the case of a 53-year old man with progressive double vision due to isolated left trochlear nerve palsy. Cranial magnetic resonance imaging (MRI) showed a small tumor within the left quadrigeminal cistern that did not increase in size after several months. Explorative neurosurgical intervention revealed a left trochlear nerve cavernoma. The lesion was microsurgically excised followed by end-to-end anastomosis of the trochlear nerve. After a one-year follow up, double vision totally disappeared and cranial MRI showed no recurrence. Cerebral cavernous malformations usually become symptomatic in seizures or focal neurological deficits after intracerebral hemorrhage. Rarely, cavernomas arise from cranial nerves. To the authors' knowledge, this is the first report on a symptomatic cavernous malformation arising from the trochlear nerve and on its successful surgical management.

Elevated HLA-E levels in human glioblastomas but not in grade I to III astrocytomas correlate with infiltrating CD8+ cells

HLA-E is a ligand for the immune-inhibitory NKG2A receptor expressed on NK and T cells. To investigate HLA-E expression and immune cell infiltration in human astrocytic tumors in vivo, we analyzed normal CNS controls and astrocytomas of all WHO grades by immunohistochemistry. Both, CD8(+) immune cell infiltration and HLA-E expression were significantly higher in astrocytic tumors than in normal brain. Further, HLA-E expression levels and immune cell infiltration were significantly correlated in WHO grade IV glioblastomas. Thus, HLA-E overexpression in glioblastomas may be triggered by T and NK cell infiltration.

Efficacy and Tolerability of Temozolomide in an Alternating Weekly Regimen in Patients With Recurrent Glioma

Purpose

Evaluation of toxicity and efficacy of an alternating weekly regimen of temozolomide administered 1 week on and 1 week off in patients with recurrent glioma.

Patients and Methods

Ninety adult patients with recurrent gliomas accrued in one center received chemotherapy with temozolomide at 150 mg/m2/d (days 1 through 7 and 15 through 21 every 4 weeks) with individual dose adjustments according to hematologic toxicity.

Results

A total of 906 treatment weeks were delivered. Grade 4 hematotoxicity according to the Common Terminology Criteria for Adverse Events (CTCAE; version 3.0) was observed in 24 treatment weeks (2.6%). CTCAE grade 4 lymphopenia eventually developed in 11 patients (12%). There were neither cumulative lymphopenias nor opportunistic infections. The progression-free survival (PFS) rate at 6 months for glioblastoma patients was 43.8%. The median PFS in these patients was 24 weeks (95% CI, 17 to 26 weeks), the median survival time from diagnosis of progression was 38 weeks (95% CI, 30 to 46 weeks), and the 1-year survival rate from progression was 23%. O6-methylguanine DNA methyltransferase (MGMT) gene promoter methylation in the tumor tissue was not associated with longer PFS (log-rank P = .37).

Conclusion

These data imply that the alternating weekly schedule is feasible, safe, and effective and clearly warrants investigation in randomized studies. Compared with more protracted low-dose temozolomide schedules, the 1-week-on/1-week-off schedule may be less toxic. We provide preliminary evidence that this dose-dense schedule is also active in patients with tumors lacking MGMT gene promoter methylation.

Multifocal dysembryoplastic neuroepithelial tumor with signs of atypia after regrowth

We report the case of a multifocal dysembryoplastic neuroepithelial tumor (DNT) in a 7-year-old girl with local tumor regrowth 6 years later. The tumor was localized in the right parietal lobe extending from the cortex into the periventricular white matter. After subtotal resection of a histopathologically confirmed DNT we observed unexpected tumor progression in long-term follow-up. Therefore, a second surgery was performed when the patient was 14 years of age. In neuropathological examination of the second specimen the tumor showed an increased cellularity and pleomorphism, microvascular proliferations, an elevated proliferative activity (MIB1-index focally up to 10%) and cellular atypia not typical for WHO grade I DNT. Furthermore, MRI studies showed additional supratentorial and infratentorial lesions which remained stable over years and are also well consistent with DNTs. Thus, an unusual form of a DNT with multifocal lesions, local regrowth and morphological transformation is supposed.

WHO grade associated downregulation of MHC class I antigen-processing machinery components in human astrocytomas: does it reflect a potential immune escape mechanism?

Defects of major histocompatibility complex (MHC) class I antigen-processing machinery (APM) components have been shown to contribute to immune escape of malignant cells. We investigated the expression of APM components in astrocytomas without detectable defects in HLA class I antigen expression and correlated it with grade of malignancy. Quantitative immunohistochemical analysis of astrocytomas revealed reduced expression of the cytosolic proteasome subunit low molecular weight protein 2 (LMP2), the endoplasmatic reticulum (ER) transporter associated with antigen processing-1 (TAP1), and the ER chaperone beta2-microglobulin (beta2m) in astrocytoma cells when compared to astrocytes from nonpathological brain. Among human WHO grade II-IV astrocytomas, downregulation of LMP2, TAP1 and beta2m correlated with grade of malignancy. Furthermore, astrocytoma cell lines (n = 12) expressed all APM components analyzed at levels comparable to dendritic cells (DC), which were used for comparative purposes. However, upregulation of beta2m after stimulation with inflammatory cytokines was significantly lower in astrocytoma cell lines than in control cells. Our results support the hypothesis that coordinated downregulation or impaired upregulation of certain HLA class I APM components may serve as a mechanism for astrocytoma cells to evade the host's immune response, even if HLA class I antigen surface expression is not altered.

Reactive astrocytes and activated microglial cells express EAAT1, but not EAAT2, reflecting a neuroprotective potential following ischaemia

AIMS

Glutamate receptor antagonists have failed clinical stroke trials and it has been proposed that the action of N-methyl D-aspartate receptors is necessary for neuronal survival. Thus, excitatory amino acid transporters (EAATs) might be a promising therapeutic target. The aim of this study was to investigate glial expression of EAATs following ischaemia.

METHODS AND RESULTS

Expression of EAAT1 (GLAST) and EAAT2 (Glt-1) in 24 cases of ischaemia was examined by immunohistochemistry. Cortical expression of both EAATs in the lesion decreased within 24 h (P < 0.01, each). Whereas EAAT1+ white matter cells increased 18-fold (P < 0.05) within 24 h in the lesion and remained elevated for months in adjacent (469-fold, P < 0.01) and remote areas (20-fold, P < 0.05), EAAT2+ white matter cells were equivalent in ischaemia and controls. In the first week after stroke mainly activated (ramified and amoeboid) microglia expressed EAAT1, whereas monocytic cells in perivascular spaces and foamy macrophages lacked EAAT1. After more than 1 week, predominantly reactive astrocytes expressed EAAT1.

CONCLUSIONS

Microglial EAAT1 expression is restricted to the early/intermediate stage of activation and blood-derived (perivascular) monocytes do not contribute to EAAT1+ cells following ischaemia. Whether a pharmacological increase in glial EAAT expression may compensate for loss of cortical EAAT expression and reduce neuronal damage following stroke requires investigation by further functional studies.

Expression of interleukin-16 by tumor-associated macrophages/activated microglia in high-grade astrocytic brain tumors

Introduction

Macrophages/microglial cells are considered as immune cells in the central nervous system. Interleukin (IL)-16 is a proinflammatory cytokine produced by activated monocytic cells.

Materials and Methods

Expression of IL-16 was analyzed by immunohistochemistry in human astrocytic brain tumors and the rat C6 glioblastoma tumor model. IL-16 was detected in both human astrocytic brain tumors and rat C6 glioma.

Results

Compared with human control brains, a significant increase in the percentages of parenchymal IL-16⁺ macrophages/microglia was observed already in grade II astrocytomas, indicating that IL-16⁺ immunostaining could be a descriptor of a macrophage/microglia subset in astrocytic brain tumors. A further increase was observed at the transition from grade II to III astrocytomas. This increase in IL-16 immunoreactivity correlated with WHO grades of human astrocytic brain tumors.

Conclusions

Therefore, IL-16 might be a so far unknown factor in the regulation of the local inflammatory milieu of human and experimental astrocytomas.