Vascular endothelial growth factor expression in oligodendrogliomas: a correlative study with Sainte-Anne malignancy grade, growth fraction and patient survival

Identification of Grade-associated MicroRNAs in Brainstem Gliomas Based on Microarray Data

Gliomas arising in the brainstem are rare tumours that are difficult to surgically resect, and the microRNAs (miRNAs) and signalling pathways associated with brainstem gliomas (BSGs) are largely unknown. To identify grade-associated miRNAs in BSGs, a microarray analysis of 10 low-grade and 15 high-grade BSGs was performed in this study. Differentially expressed miRNAs (DE-miRNAs) were identified, and the functional DE-miRNAs were selected. The potential target genes and enriched pathways were analysed, and a target gene-associated protein-protein interaction (PPI) network was generated. Grade-associated functional DE-miRNAs were confirmed by real-time quantitative PCR. First, 28 functional DE-miRNAs, including 13 upregulated miRNAs and 15 downregulated miRNAs, were identified. Second, 2546 target genes that were involved in BSG-related pathways, such as signalling pathways regulating the pluripotency of stem cells, the AMPK signalling pathway, the HIF-1 signalling pathway, the PI3K-Akt signalling pathway, the Wnt signalling pathway and the Hippo signalling pathway, were screened. Third, PHLPP2 and VEGFA were identified as hub genes in the PPI network. Last, we found that hsa-miR-34a-5p inhibits BSG cell invasion in vitro. In summary, using integrated bioinformatics analysis, we have identified the potential target genes and pathways of grade-associated functional DE-miRNAs in BSGs, which could improve the accuracy of prognostic evaluation. Furthermore, these hub genes and pathways could be therapeutic targets for the treatment of BSGs.

Tumor suppressor microRNA‑613 inhibits glioma cell proliferation, invasion and angiogenesis by targeting vascular endothelial growth factor A

MicroRNAs (miRNAs) are small non‑coding RNAs which can serve as oncogenes or tumor suppressors in glioma. The present study aimed to investigate the expression of miR‑613 in glioma. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was used to detect miR‑613 in glioma cells and tissues and the relationship between miR‑613 and vascular endothelial growth factor (VEGF) A was assessed using a luciferase reporter assay. In addition, glioma cells were transfected with miR‑613 mimics and the mRNA and protein expression of VEGFA was detected using RT‑qPCR and western blot analysis, respectively. The proliferative, invasive and tube formation capabilities of transfected cells were also assessed in vitro. Furthermore, a nude mouse tumor xenograft model was used to investigate the effects of miR‑613 on tumor growth in vivo. The results of the present study demonstrated that the expression of miR‑613 was decreased in glioma cell lines, and was associated with the grade of glioma. Ectopic expression of miR‑613 markedly suppressed glioma cell proliferation and angiogenesis. Furthermore, the upregulation of miR‑613 inhibited tumor angiogenesis and tumor growth in xenografted nude mice in vivo. VEGFA was demonstrated as a direct target of miR‑613, as detected by western blot and luciferase reporter assays, and mediated miR‑613 induced glioma cell proliferation and angiogenesis inhibition.

Low-grade and anaplastic oligodendrogliomas: differences in tumour microvascular permeability evaluated with dynamic contrast-enhanced magnetic resonance imaging

This study was designed to quantitatively assess the microvascular permeability of oligodendroglioma using the volume transfer constant (K(trans)) and the volume of the extravascular extracellular space per unit volume of tissue (V(e)) with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). We aimed to evaluate the effectiveness of K(trans) and V(e) in distinguishing between low-grade and anaplastic oligodendroglioma. The maximal values of K(trans) and V(e) for 65 patients with oligodendroglioma (27 grade II, 38 grade III) were obtained. Differences in K(trans) and V(e) between the two groups were analysed using the Mann-Whitney rank-sum test. Receiver operating characteristic (ROC) curve analyses were performed to determine the cut-off values for the K(trans) and Ve that could differentiate between low-grade and anaplastic oligodendrogliomas. Values for K(trans) and Ve in low-grade oligodendrogliomas were significantly lower than those in anaplastic oligodendrogliomas (p < 0.001 and p < 0.001, respectively). ROC curve analysis showed that cut-off values of the K(trans) (0.037 min(-1)) and Ve (0.079) could be used to distinguish between low-grade and anaplastic oligodendrogliomas in a statistically significant manner. Our results suggest that DCE-MRI can distinguish the differences in microvascular permeability between low-grade and anaplastic oligodendrogliomas.

Novel approach to analysis of in vitro tumor angiogenesis with a variable-pressure scanning electron microscope: suppression by matrix metalloproteinase inhibitor SI-27

Degradation of basement membrane by metalloproteinases (MMP) is a critical step in tumor angiogenesis. To evaluate in vitro angiogenesis, several models have been employed, including bovine cornea, fenestrated rat brain, Matrigel, and others. These models did not provide quantitative analysis of capillary formation. The current study aimed for a novel approach to in vitro assay of angiogenesis with a "wet scanning electron microscope (SEM)" to investigate suppression of tumor angiogenesis by the MMP inhibitor, SI-27. The effects of noncytotoxic concentrations of SI-27 (1-100 microM) were determined on nonmitogenic vascular endothelial growth factor (VEGF) (10 ng/ml)-mediated cell motility and in vitro angiogenesis of human umbilical vein endothelial cells (HUVECs). Activities of MMP and tissue inhibitor of metalloproteinase (TIMP) were determined by enzyme-linked immunosorbent assay (ELISA). Subsequently, the inhibitory effect of SI-27 was examined on in vitro angiogenesis stimulated by supernatants of human glioma cell lines (U87MG, U251MG, or U373MG). In vitro angiogenesis was quantitatively analyzed with a variable-pressure SEM. Cell motility and in vitro angiogenesis by HUVECs were significantly increased by VEGF along with elevated MMP-1 and -2 activity, whereas SI-27 significantly suppressed VEGF-mediated in vitro angiogenesis and inactivated both MMP-1 and MMP-2, but not inhibited cell motility. The angiogenesis promoted by glioma supernatants showed a significant reduction in the presence of SI-27. SI-27, a novel MMP inhibitor, inhibited tumor angiogenesis in vitro. It can be anticipated to prevent tumor growth through its angiosuppressive effect. Quantitative analysis with a variable-pressure SEM is a novel approach to in vitro angiogenesis assay.

MicroRNA-205 functions as a tumor suppressor in human glioblastoma cells by targeting VEGF-A

MicroRNAs (miRNAs) are endogenously small non-coding RNAs which are key post-transcriptional regulators of gene expression. Deregulation of miRNAs is common in human tumorigenesis. We report that miRNA-205 is significantly down-regulated in glioma cell lines and tissue specimens. Ectopic expression of miRNA-205 induces apoptosis, cell cycle arrest, impairs cell viability, clonability and invasive properties of glioma cells. We further demonstrate that miRNA-205 can specifically suppress expression of VEGF-A by directly interacting with the putative miRNA-205 binding site at the 3′-UTR. Identification of VEGF-A as a direct target for miRNA-205 may imply that miRNA-205 is a novel target for glioma therapy. Taken together, the present study for the first time provides evidence that miRNA-205 is a glioma-specific tumor suppressor by targeting VEGF-A.

Assessment of tumor angiogenesis as a prognostic factor of survival in patients with oligodendroglioma

According to World Health Organization (WHO) and Daumas-Duport grading systems, progression of oligodendrogliomas (ODGs) to a higher grade (WHO grade III, grade B) is associated with increased angiogenesis. Based on multivariate assessment of molecular, pathological, and radiological parameters, we further assessed the influence of tumor angiogenesis on tumor progression and patient survival. Patients with a diagnosis of ODG, consecutively treated in a single institution, were reviewed and reclassified according to WHO and Daumas-Duport grading systems. MRI scans were reviewed to assess contrast enhancement and necrosis. Tissue sections were used for pathology review and to evaluate immunostaining of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor (VEGF-R), Ki-67, and CD34. Multivariate analysis was performed to assess the impact of tumor angiogenesis-related pathological and radiological factors on patient survival. One hundred thirty-four patients with pure ODG were included in this study. Multivariate analysis identified four independent poor prognostic factors: necrosis, absence of seizure, increased vascularization, and age >55 years. A subgroup of patients with tumor necrosis, increased vascularization, and absence of seizures had a significantly worse outcome than predicted, with a median overall survival of 14.2 months. VEGF expression was significantly higher in this subgroup and correlated with disease progression regardless of histologic grade. Based on the presence of radiological or pathological necrosis, contrast enhancement or endothelial hyperplasia, and absence of seizures, a high risk group of ODG can be identified with significantly worse overall survival. Also, VEGF over-expression in ODG constitutes an early marker for predicting tumor progression.

Regional hypoxia in glioblastoma multiforme quantified with [18F]fluoromisonidazole positron emission tomography before radiotherapy: correlation with time to progression and survival

PURPOSE

Hypoxia is associated with resistance to radiotherapy and chemotherapy and activates transcription factors that support cell survival and migration. We measured the volume of hypoxic tumor and the maximum level of hypoxia in glioblastoma multiforme before radiotherapy with [(18)F]fluoromisonidazole positron emission tomography to assess their impact on time to progression (TTP) or survival.

EXPERIMENTAL DESIGN

Twenty-two patients were studied before biopsy or between resection and starting radiotherapy. Each had a 20-minute emission scan 2 hours after i.v. injection of 7 mCi of [(18)F]fluoromisonidazole. Venous blood samples taken during imaging were used to create tissue to blood concentration (T/B) ratios. The volume of tumor with T/B values above 1.2 defined the hypoxic volume (HV). Maximum T/B values (T/B(max)) were determined from the pixel with the highest uptake.

RESULTS

Kaplan-Meier plots showed shorter TTP and survival in patients whose tumors contained HVs or tumor T/B(max) ratios greater than the median (P < or = 0.001). In univariate analyses, greater HV or tumor T/B(max) were associated with shorter TTP or survival (P < 0.002). Multivariate analyses for survival and TTP against the covariates HV (or T/B(max)), magnetic resonance imaging (MRI) T1Gd volume, age, and Karnovsky performance score reached significance only for HV (or T/B(max); P < 0.03).

CONCLUSIONS

The volume and intensity of hypoxia in glioblastoma multiforme before radiotherapy are strongly associated with poorer TTP and survival. This type of imaging could be integrated into new treatment strategies to target hypoxia more aggressively in glioblastoma multiforme and could be applied to assess the treatment outcomes.

Vascular endothelial growth factor mRNA expression and peritumoral edema in canine primary central nervous system tumors

Vascular endothelial growth factor (VEGF) is an important regulator of tumor angiogenesis and vascular permeability, and has been implicated both in progression of central nervous system (CNS) tumors and development of vasogenic peritumoral edema. A retrospective study was done to characterize the levels of expression of the 3 major canine VEGF isoforms (VEGF(120), VEGF(164), VEGF(188)) in a variety of spontaneous canine CNS tumors using quantitative TaqMan reverse transcription real-time polymerase chain reaction. Presence and degree of peritumoral edema also were determined in sampled tumors using magnetic resonance imaging (MRI). Increased expression of VEGF relative to normal cerebral cortex tissue was seen predominantly in high grade astrocytic (grade IV) and oligodendroglial (grade III) tumors, with lower expression in low grade astrocytomas (grade II) and meningiomas (grade I). All 3 major VEGF isoforms were present; VEGF(164) was the predominant isoform, particularly in the tumors with the highest VEGF expression. Peritumoral edema was present in all tumor types; however, a significant association between the extent of peritumoral edema and the level of VEGF expression was not apparent.

Immunohistochemical evaluation of the microvascular density through the expression of TGF-beta (CD 105/endoglin) and CD 34 receptors and expression of the vascular endothelial growth factor (VEGF) in oligodendrogliomas

Angiogenesis has been proposed as essential for the growth of solid tumors. The determinants of this process, the growth factors and the vascular endothelial receptors have brought a potential in the tumor prognostic determination as well as perspectives of "targets" for antiangiogenic therapy. In oligodendrogliomas (OL), angiogenesis is little known and/or has generated conflicting results. In order to clarify angiogenesis in OL, we have evaluated the immunohistochemical expression of vascular endothelial growth factor (VEGF) and the microvascular density (MVD) through the expression of TGF-beta (CD105/endoglin) (MVD-CD105) and CD34 (MVD-CD34) receptors using the Chalkley point method in 30 OL. No significant immune reaction was found for the VEGF. There was expression in <10% of tumor cells and/or staining of weak intensity in 15 (50.0%), >10% of cells and moderate intensity staining in 1 (3.33%), and negative expression in 14 (46.67%). If present, the expression was restricted to tumor and endothelial cells. Our findings suggest that VEGF has little influence on OL angiogenesis. All specimens showed CD105 and CD34 expression in the intratumor vascular endothelium, suggesting involvement of CD105 in OL angiogenesis. The mean +/- SD MVD-CD105 and MVD-CD34 were 10.83 +/- 2.24 and 11.00 +/- 2.76 in OL (P = 0.086; r = 0.319); 10.00 +/- 2.00 and 10.40 +/- 3.02 in OL grade II (n = 15) (P = 0.547; r = 0.105), and 11.67 +/- 2.22 and 11.53 +/- 2.45 in OL grade III (n = 15) (P = 0.817; r = 0.551), respectively. The absence of correlation between DMV-CD105, DMV-CD34 and tumor grades suggests that anti-CD105 and anti-CD34 antibodies have different vascular specificities. MVD-CD105 was greater in OL grade III than in OL grade II (P = 0.0032), indicating an increase in the vascular neoformation, something which must be evaluated as a possible prognostic factor in OL. Both TGF-beta and CD105 bring perspectives as "targets" for antiangiogenic treatments in OL.

High cerebral blood volume in human gliomas predicts deletion of chromosome 1p: Preliminary results of molecular studies in gliomas with elevated perfusion

PURPOSE

To determine if increased perfusion using dynamic susceptibility contrast perfusion MRI (DSC MRI) in gliomas may be predictive of 1p19q deletions. Loss of heterozygosity of chromosomes 1p and 19q confers responsiveness to chemotherapy improving survival in gliomas.

MATERIALS AND METHODS

We retrospectively reviewed 16 patients who had DSC MRI and molecular studies of their excised gliomas for 1p19q deletions. Allelic status was assessed by loss of heterozygosity using polymerase chain reaction (PCR). DNA was extracted from paraffin curls of brain tumor sections and nail clippings. Relative cerebral blood volume (rCBV) measurements were then statistically compared with the presence of 1p and 19q deletions.

RESULTS

Patients with 1p19q deletions (N = 7) demonstrated rCBV values of 10.54 +/- 2.93. Patients without 1p deletions (N = 9) had rCBV values of 4.84 +/- 2.4 (P = 0.012). Logistic regression demonstrated that rCBV was able to predict the presence of a 1p deletion to significance levels of 0.038 and 0.044, adjusted and not adjusted for age and sex, respectively. The kappa coefficient for the agreement between predicted deletion status using rCBV and the truedeletion status was 0.746 (P = 0.0028). Deletions of 19q alone, or together with 1p deletions, were not associated with high rCBV.

CONCLUSION

Histopathologic, molecular, and imaging evidence supports increased neovascularity in gliomas with 1p deletions in this preliminary study. We propose a diagnostic algorithm to obtain molecular studies in gliomas demonstrating high rCBV.

Cerebral Blood Volume Measurements and Proton MR Spectroscopy in Grading of Oligodendroglial Tumors

OBJECTIVE

The purpose of this study was to determine whether perfusion-weighted imaging (PWI) and proton MR spectroscopy (MRS) are useful in differentiating high- and low-grade oligodendroglial tumors.

MATERIALS AND METHODS

PWI and MRS studies of 22 patients with histologically proven oligodendroglioma or oligoastrocytoma (13 low-grade and nine anaplastic tumors) were retrospectively reviewed. PWI of 14 subjects was performed with a dynamic contrast-enhanced susceptibility-weighted echo-planar technique. Intratumoral relative cerebral blood volume ratio was calculated and normalized to the same value in contralateral normal-appearing white matter. Multivoxel MRS was performed with a point-resolved spectroscopy sequence at a TE of 135 milliseconds in 20 patients and with the addition of a TE of 30 seconds in 17 patients. MRS data were expressed as intratumoral metabolite ratios (choline to creatine [Cho/Cr], choline to N-acetyl aspartate, N-acetyl aspartate to creatine, and myoinositol to creatine).

RESULTS

Relative cerebral blood volume ratios were significantly different (p = 0.004) between low-grade (1.61 +/- 1.20) and high-grade tumors (5.45 +/- 1.96). The optimal relative cerebral blood volume ratio cutoff value in identification of anaplastic oligodendroglial tumors was 2.14. Analysis of MRS data showed significantly higher Cho/Cr ratios (p = 0.002) in high-grade than in low-grade tumors. A Cho/Cr ratio cutoff value of 2.33 had the highest accuracy in identification of high-grade tumors.

CONCLUSION

Relative cerebral blood volume measurement and MRS are helpful in differentiating low-grade from anaplastic oligodendroglial tumors.

Molecular diagnostics in central nervous system tumors

Central nervous system (CNS) neoplasms can be diagnostically challenging, due to remarkably wide ranges in histologic appearance, biologic behavior, and therapeutic approach. Nevertheless, accurate diagnosis is the critical first step in providing optimal patient care. As with other oncology-based specialties, there is a rapidly expanding interest and enthusiasm for identifying and utilizing new biomarkers to enhance the day-to-day practice of surgical neuropathology. In this regard, the field is primed by recent advances in basic research, elucidating the molecular mechanisms of tumorigenesis and progression in the most common adult and pediatric brain tumors. Thus far, few have made the transition into routine clinical practice, the most notable example being 1p and 19q testing in oligodendroglial tumors. However, the field is rapidly evolving and many other biomarkers are likely to emerge as useful ancillary diagnostic, prognostic, or therapeutic aids. The goal of this article is to highlight the most common genetic alterations currently implicated in CNS tumors, focusing most on those that are either already in common use in ancillary molecular diagnostics testing or are likely to become so in the near future.

Functional endothelin ET B receptors are selectively expressed in human oligodendrogliomas

Endothelin-1 (ET-1), a vasoactive and mitogenic peptide mainly produced by vascular endothelial cells, may be involved in the progression of several human tumors. Here, we present an immunohistochemical analysis of the expression pattern of ET-1 receptor subtypes (ET(A)-R and ET(B)-R) and a functional study of their potential role in human oligodendrogliomas and oligoastrocytomas. By comparison, we assessed the corresponding expression patterns of glioblastomas. Interestingly, a nuclear localization of ET-1 receptor subtypes (associated or not with a cytoplasmic labeling) was constantly observed in tumor cells from all three glioma types. Moreover, we noted a distinct receptor distribution in the different gliomas: a nuclear expression of ET(B)-R by tumor cells was found to be restricted to oligodendrogliomas and oligoastrocytomas, while a nuclear expression of ET(A)-R was only detected in tumor cells from some glioblastomas. Using primary cultures of oligodendroglial tumor cells, we confirmed the selective expression of nuclear ET(B)-R, together with a plasma membrane expression, and further demonstrated that this receptor was functionally coupled to intracellular signaling pathways known to be involved in cell survival and/or proliferation: extracellular signal-regulated kinase and focal adhesion kinase activation, actin cytoskeleton reorganization. In addition, impairment of ET(B)-R activation in these cells by in vitro treatment with an ET(B)-R-specific antagonist induced cell death. These data point to ET-1 as a possible survival factor for oligodendrogliomas via ET(B)-R activation and suggest that ET(B)-R-specific antagonists might constitute a potential therapeutic alternative for oligodendrogliomas.

Altered molecular pathways in gliomas: An overview of clinically relevant issues

Primary central nervous system (CNS) tumors constitute a small fraction of the overall incidence of human cancer, but they represent a major source of cancer-related morbidity and mortality. The most common CNS tumor subtype in adults, high-grade astrocytoma, confers a dismal prognosis with a median survival of only 1 to 2 years. Other common adult CNS tumors, ie, low-grade astrocytomas and oligodendrogliomas, carry a less ominous, yet still poor prognosis. Unfortunately, there has been little progress in extending the survival or quality of life for glioma patients, despite nearly four decades of extensive research. This research has, however, greatly increased our understanding of the underlying molecular biology of these tumors, examples of which include the determination of elevated epidermal growth factor receptor (EGFR) as well as platelet-derived growth factor receptor (PDGF) signaling, and the inactivation of p53 , p16 , and PTEN tumor-suppressor genes (TSGs) that negatively regulate specific enzymatic activities in normal glial cells. Such observations have greatly improved our understanding of the pathogenesis of these tumors and have potential diagnostic as well as therapeutic relevance. With respect to the latter of these two issues, the identification of aberrant enzymatic activities in gliomas has promoted the development of novel therapeutic agents that target specific signaling effectors, and whose inhibition should, in theory, prove to be cytostatic, if not cytotoxic, to tumor cells. Several clinical trials are currently underway for testing these therapeutic agents in patients with primary brain tumors, and it is hoped that the targeting of pro-tumorigenic enzymatic activities will lead to better patient outcomes. In this review, we will describe the most pertinent genetic and signaling pathway alterations that are clinically relevant to the management of glial tumors.

Drug-induced apoptosis by a matrix metalloproteinase inhibitor, SI-27 on human malignant glioma cell lines; in vitro study

Matrix metalloproteinase (MMP) plays important roles in cell invasion and tumor angiogenesis. SI-27, an anti-MMP agent, has already been shown to possess both in vitro anti-invasive and anti-angiogenic properties against malignant gliomas in non-cytotoxic dose concentrations. However, to the best of our knowledge, the molecular mechanism mediating the cytotoxic action by this agent and the molecular mechanism in the cytotoxic action against malignant glioma cell have not yet been clarified. Therefore, we assessed the effect in the cytotoxic dose concentrations to investigate whether this cytotoxic action is related to apoptosis in this study. The effect on human glioma cell lines (U87MG, U251MG, and U373MG) was examined by transmission electron microscope, agarose gel electrophoresis with the DNA fragmentation, flow cytometry with FITC-conjugated Annexin V, and detection of caspase activity. Drug-induced apoptosis was observed in the cytotoxic dose. The result indicated that the cytotoxity of SI-27 might be related to the drug-induced apoptosis mediated by caspase.

Tumour necrosis and microvascular proliferation are associated with 9p deletion and CDKN2A alterations in 1p/19q -deleted oligodendrogliomas

A subset of oligodendrogliomas and oligoastrocytomas has been associated with 1p/19q deletion. Subsequently, this genetic alteration was linked to chemosensitivity and classic histology of oligodendrogliomas. Tumoural progression includes deletions of 9p, 10q and alterations of CDKN2A. However, these (epi)genetic changes have not been associated with specific histological features. In a series of 45 gliomas including oligodendrogliomas, oligoastrocytomas and astrocytomas, deletions of chromosomal regions implied in these tumours (1p, 9p, 10, 17p13, 19q and 22) were looked for by microsatellite analysis. Tumours that were deleted for 1p and 19q were selected. Subsequently, presence of deletions in the other studied regions, (epi)genetic changes in p14ARF, CDKN2A and CDKN2B, as well as histological features, were associated to these tumours. 1p/19q deletion was observed in 22 tumours. Twenty-one of them presented regions of classic histology of oligodendroglioma. A deletion of 9p was found in eight of them, always in association with tumour necrosis and/or microvascular proliferation. In addition, (epi)genetic alterations of CDKN2A were observed in 71% of these tumours. Presence of regions of classic histology of oligodendroglioma in a tumour sample is predictive of 1p/19q deletions. Necrosis and/or microvascular proliferation are signs of an additional 9p deletion. Finally, as CDKN2A (epi)genetic alterations were found in 71% of the 1p/19q/9p-deleted oligodendrogliomas, CDKN2A may have a role in oligodendroglioma-associated microvascular proliferation.

Immunohistochemical markers for prognosis of oligodendroglial neoplasms

Despite numerous previous studies, oligodendrogliomas continue to generate considerable controversy in the identification of prognostic factors, including single histopathological patterns, and grade of tumor malignancy. The prognostic significance of various pathological and immunohistochemical factors has been intensively examined but numerous studies have yielded conflicting results. In the present study, biopsy samples of 123 oligodendrogliomas were examined immunohistochemically to evaluate a possible association between expression of various tumor-associated antigens and clinical outcome. Both the progression-free and overall survival times were significantly reduced for high-grade tumors, for Ki-S1 labeling index (LI) > 10%, for p27 LI < 20% and for p18, p53, and vascular endothelial growth factor (VEGF)-positive tumors. For low-grade tumors survival rates were significantly reduced for p27 LI less than 20%, whereas high-grade oligodendrogliomas with Ki-S1 LI greater than 10%, and with p18 positivity revealed significantly shortened survival times. We found no differences in survival times in patients with or without p 14ARF, p21, mdm2, and pRb immunoreactivity. Multivariate analysis revealed that risk of oligodendroglioma progression is associated with high-grade tumors, with Ki-S1 LI > 10%, and with p27 LI < 20%; whereas risk of death is associated with high-grade tumors, with Ki-S1 LI > 10%, and with p18 positivity. CART modeling process identified four final groups of oligodendroglioma patients: (1) thirty-nine patients with low-grade tumors and p27 LI > 20%; (2) twenty patients with low-grade tumors and p27 LI < 20%; (3) thirty-four patients with high-grade tumors and Ki-S1 LI < 10%; and (4) thirty patients with high-grade tumors and Ki-S1 LI >10%. In summary, both the p27 and Ki-S1 scores were found to be the strong predictors of oligodendroglioma outcome together with the WHO tumor grade and they seem to be useful for assessing individual prognosis in routinely processed specimens.

Extradural cord compression due to metastatic oligodendroglioma

Extraneural metastases from primary intracranial tumours are extremely rare. We present a case of metastatic oligodendroglioma causing extradural spinal cord compression at the level of the sixth thoracic vertebrae resulting in paraplegia. We discuss the routes of tumour dissemination and possible reasons for the rarity of cases of metastatic oligodendroglioma.

SI-27, a novel inhibitor of matrix metalloproteinases with antiangiogenic activity: detection with a variable-pressure scanning electron microscope

OBJECTIVE

Degradation of basement membrane is one the of crucial steps in tumor angiogenesis and is performed by matrix metalloproteinases (MMPs). This study was designed to investigate the suppression of tumor angiogenesis by SI-27, an MMP inhibitor.

METHODS

SI-27 was applied at noncytotoxic concentrations (1-100 micromol/L), and its effect on nonmitogenic vascular endothelial growth factor (VEGF)-enhanced cell motility and in vitro angiogenesis by human umbilical vein endothelial cells was determined. The activity of MMP-1, MMP-2, and tissue inhibitor of metalloproteinase 1 was determined by enzyme-linked immunosorbent assay. The effect of SI-27 on in vitro angiogenesis stimulated by supernatants of human glioma cell lines (U87MG, U251MG, and U373MG) also was examined. Angiogenesis was detected with variable vacuum scanning electron microscopy.

RESULTS

Cell motility and in vitro angiogenesis by human umbilical vein endothelial cells were significantly increased by VEGF. The maximal effect on cell motility by VEGF was noted at 5 ng/ml (P < 0.001), and the maximal effect on the capillary network was observed at 10 ng/ml (P < 0.001), along with elevated MMP-1 and MMP-2 activity. Whereas SI-27 significantly suppressed VEGF-mediated in vitro angiogenesis (50 micromol/L; P < 0.001) and inactivated both MMP-1 and MMP-2, the expression of tissue inhibitor of metalloproteinase 1 and VEGF-mediated cell motility were not affected by SI-27. The angiogenesis promoted by glioma supernatants showed a significant reduction in the presence of SI-27 (10 micromol/L; U87MG, P < 0.01; U251MG, P < 0.01; U373MG, P < 0.01).

CONCLUSION

SI-27 inhibited in vitro tumor angiogenesis by suppression of MMP. This agent may be anticipated to prevent tumor growth through an angiosuppressive effect.

Immunohistochemical analysis of p18INK4C and p14ARF protein expression in 117 oligodendrogliomas: correlation with tumor grade and clinical outcome

OBJECTIVE

To investigate immunoexpression of 2 cyclin-dependent kinase inhibitors, p18INK4C (p18) and p14ARF (p14), in oligodendrogliomas and to evaluate the possible association with tumor grade and clinical outcome.

DESIGN

One hundred seventeen specially selected cases of cerebral oligodendrogliomas were studied retrospectively. Tumor specimens were immunohistochemically examined with antibodies to p18INK4C (118.2) and p14ARF (FL-132) proteins. A computerized color image analyzer was used to count immunostained nuclei.

RESULTS

p18 nuclear immunoexpression was found in 57 (49%) of the oligodendrogliomas we studied. p18 immunoreactivity exhibited a clear tendency to elevate with increasing tumor grade, and the mean p18 labeling index was 9.7% for low-grade (World Health Organization [WHO] grade II) and 19.2% for high-grade (WHO III) tumors. p14-immunopositive nuclei were found in 87 (74%) tumors, and p14 immunoreactivity showed no correlation with oligodendroglioma histological malignancy. Survival times were significantly reduced for p18-positive tumors, and risk of death was independently associated with p18 expression (hazard ratio = 2.48; P =.01). There was no difference in survival times in patients with or without p14 immunoreactivity.

CONCLUSIONS

p18 protein expression is closely associated with malignant oligodendrogliomas and worse clinical outcome. It seems unlikely that p14 immunohistochemistry will be of value in assessing individual prognosis for these tumors.

Expression of vascular endothelial growth factors and their receptors in and around intracranial arteriovenous malformations

OBJECTIVE

The precise mechanisms responsible for the development and growth of intracranial arteriovenous malformations (AVMs) remain unclear, but it has been hypothesized that vascular endothelial growth factors (VEGFs) might be involved in their pathogenesis. The aim of this study was to examine immunohistochemically the presence of the VEGF family (VEGF-A to -D) and their receptors (Flt-1, Flk-1, and Flt-4) in the surgically resected AVM nidus.

METHODS

The AVM nidus was surgically obtained from 31 patients with AVMs (mean age, 40.5 yr, range 13-73 yr). The mean size of the nidus was 31.6 mm (range, 15-60 mm). Formalin-fixed, paraffin-embedded specimens were stained immunohistochemically by the labeled streptavidin-biotin method with antibodies against VEGF-A to -D, as well as Flt-1, Flk-1, and Flt-4.

RESULTS

Positive staining for VEGF-A to -D was observed in the endothelial cells of the abnormal vessels involved in the AVM nidus and in the cytoplasm of astroglia surrounding it. Samples from 30 (96.8%) of 31 patients stained positive for VEGF-A, 4 (9.7%) for VEGF-B, 17 (54.5%) for VEGF-C, and 16 (51.6%) for VEGF-D. Flt-1, Flk-1, and Flt-4 were also positive chiefly, but not exclusively, in the cytoplasm of vascular endothelium and smooth muscle cells of the vascular wall. With regard to VEGF receptors, it was found that among the 31 patients studied, 19 (61.3%) were immunohistochemically positive for Flt-1, 6 (19.4%) for Flk-1, and 19 (61.3%) for Flt-4. A comparison of mean nidus size and average age at operation revealed significant differences between patients positive for VEGF-C, VEGF-D, Flt-1, or Flt-4. In contrast, there were no significant differences in nidus size and age in patients positive for VEGF-A, VEGF-B, and Flk-1.

CONCLUSION

These results strongly suggest a possible contribution of the VEGF-VEGF receptor system to the growth of intracranial AVMs.

Genetics of nervous system tumors

Genetic aberrations are being defined for the various glial tumors. Astrocytic tumors can evolve by two different pathways. The genetic aberrations now being defined for these two pathways are different and can be associated with the grade of malignancy. In oligodendrogliomas, the genetic lesions differ from the astrocytic tumors, and several markers have been linked to chemosensitivity response and survival. Genetic aberrations in ependymomas also differ from the astrocytic tumors or oligodendrogliomas. Although additional cases are needed to study the genetic aberrations, the abnormalities identified suggest that spinal cord tumors carry different markers than intracranial tumors and that the markers within the cranium may be different based on their location.

Oligodendrogliomas: clinical and genetic correlations

Oligodendrogliomas, once obscure, are now recognized as a relatively common form of primary brain tumour, and are among the most chemosensitive of all solid human malignancies. New histopathological, molecular, and genetic information has, for the first time, allowed the distinction of several subtypes of human glioma with predictable biological and clinical behaviour. Genetic markers are emerging as useful not only for the diagnosis of oligodendroglioma, but also as specific predictors of both the response to treatment and prolonged survival. This review will focus upon the past year of advances in the area of clinical-molecular genetic predictors of glioma behaviour and highlight the importance of these advances in everyday clinical practice.

The prognostic significance of DNA topoisomerase II-alpha (Ki-S1), p21/Cip-1, and p27/Kip-1 protein immunoexpression in oligodendrogliomas

OBJECTIVE

To evaluate a possible association between clinical outcome of patients with oligodendroglioma and expression of 2 cyclin-dependent kinase inhibitors, p21/Cip-1 (p21) and p27/Kip-1 (p27), and of DNA topoisomerase II-alpha (Ki-S1), which has been recently used as a marker of cellular proliferation.

DESIGN

Ninety-one specially selected patients with cerebral oligodendrogliomas treated with surgery and radiotherapy were studied retrospectively. Tumor specimens were immunohistochemically examined with antibodies to p21, p27, and Ki-S1. A computerized color image analyzer was used to count immunostained nuclei.

RESULTS

The mean Ki-S1 labeling index (LI) was found to be significantly prominent for World Health Organization (WHO) high-grade tumors (9.5% vs. 3.2% for WHO low-grade tumors). In contrast, the mean p27 LI was significantly higher for low-grade tumors (43.3% vs 25.7% for high-grade tumors). The number of p21-positive cases and the mean p21 LI were found to be relatively equal for low- and high-grade tumors. For low-grade oligodendrogliomas, the progression-free and overall survival times were found to be significantly shorter for tumors with p27 LIs less than 20%. For high-grade oligodendrogliomas, survival times were significantly reduced for tumors with Ki-S1 LIs greater than 10%. Regression-tree analysis identified 4 groups of oligodendrogliomas with distinctly different outcomes: (1) 32 patients with low-grade tumors and p27 LIs greater than 20%; (2) 14 patients with low-grade tumors and p27 LIs less than 20%; (3) 25 patients with high-grade tumors and Ki-S1 LIs less than 10%; and (4) 20 patients with high-grade tumors and Ki-S1 LIs greater than 10%.

CONCLUSIONS

Immunoreactivity for Ki-S1 and p27 was found to be useful for further subdividing oligodendroglioma prognoses among low-grade and high-grade tumors. It seems unlikely that p21 immunohistochemistry will be of value for determining clinical outcomes for patients with oligodendrogliomas.

Oligodendroglial neoplasms: current concepts, misconceptions, and folklore

Given current prognostic and therapeutic implications, the accurate classification and grading of oligodendroglial neoplasms has become critical. However, the prevalence of morphologically ambiguous gliomas, subjective histologic criteria, personal biases, oligodendroglioma mimics, and the lack of specific oligodendroglioma markers has led to high interobserver variability and created a contentious problem encountered daily in active surgical neuropathology practices. Since histologic assessment is still a powerful prognosticator, it appropriately remains the diagnostic gold standard. However, recent efforts have focused on identifying the most reproducible and clinically relevant criteria, standardizing classification and grading schemes, and searching for useful ancillary biologic and genetic markers capable of further stratifying an otherwise heterogeneous patient population. This paper reviews the morphologic and genetic spectrum of oligodendroglial neoplasms, recent diagnostic and prognostic developments, and potential future directions.