MIB-1(Ki-67) index and transforming growth factor-alpha (TGFα) immunoreactivity are significant prognostic predictors for meningiomas

Mitotic index >6, proliferating cell nuclear antigen (PCNA) index >5%, high tumour grade and absence of progesterone receptors (PR) are significant predictors for poor outcome in meningiomas. Since MIB-1 (Ki-67) is a more specific cell proliferation marker, and overexpression of TGF-alpha is also associated with tumour progression, we compared the prognostic significance of these factors with the other indices. Intracranial meningiomas from 21 men and 36 women (age 54.5±1.7, mean±sem) were classified as 24 benign, 24 atypical and nine malignant. Twenty-one of the 57 tumours recurred (mean interval to recurrence was 57.3±13.1 months). The mean follow-up period for patients without tumour recurrence was 81.9±8.7 months. MIB-1 labelling index (LI) was expressed as percentage of labelled nuclei to total tumour nuclei counted in the most densely labelled areas. Analysis of variance revealed significant differences between tumour grades for MIB-1 labelling indices (0.75±0.21 for benign, 3.2±0.57 for atypical, 6.04±1.48 for malignant; P≤0.0066), and between malignant and non-malignant meningiomas for TGFα staining scores (P≤0.029). MIB-1 LI also correlated with mitotic and PCNA indices (P≤0.0001), but not with age of the patients. Male patients had higher tumour MIB-1 LI than females (P≤0.0128). Univariate analysis indicated that MIB-1 LI>3%, TGFα score >4 (scoring scale 0–5), mitotic index >6, and negative PR status were significant factors for worse outcome. Higher MIB-1 LI, TGFα score and mitotic index as continuous variables were also significant negative predictors. With multivariate analysis, both MIB-1 LI and TGFα score remained significant factors when paired with all other variables: TGFα or MIB-1 LI, respectively, mitosis, PCNA, tumour grade, PR status, age, sex, postoperative radiation therapy. We conclude that MIB-1 LI and TGFα score are important independent prognostic indicators for patients with meningiomas.     

Proliferation and Dna fragmentation in meningioma subtypes

H. Maier, J. Wanschitz, R. Sedivy, K. Rössler, D. Öfner and H. Budka (1997) Neuropathology and Applied Neurobiology 23, 496–506 Proliferation and DNA fragmentation in meningioma subtypes Atypical meningioma has been introduced as tumour subtype of intermediate biological behaviour between classical and malignant meningiomas. To substantiate this three-step scale of malignancy, we assessed the proliferative activity reflected by Ki-67 (MIB1) labelling index (LI) in a series of 89 meningiomas, including 15 classical, 29 atypical, 35 anaplastic tumours, and 10 haemangiopericytomas and papillary meningiomas. The possible correlation of proliferation with the frequency of apoptosis and their relations to BCL-2 immunoexpression was investigated in seven classical, 10 atypical and 10 malignant meningiomas. Apoptosis was demonstrated by evaluation of the frequency of apoptotic figures, by the enzymatic technique of in situ tailing (IST) which stains apoptotic DNA fragments, and by DNA preparation and gel electrophoresis demonstrating DNA laddering in frozen tissues of five meningiomas. MIB1 LI revealed a highly significant increase from classical through atypical to anaplastic meningiomas (P 0.0001); haemangiopericytomas and papillary meningiomas were well within the range of atypical meningiomas. IST indices rose with increasing malignancy and correlated with MIB1 LI (P 0.0001); they showed a weak inverse correlation with BCL-2 immunoexpression (P= 0.05). BCL-2 expression tended to decrease with malignancy grade and was unrelated to MIB1 LI or frequency of apoptosis. Our data show that (i) apoptosis is a feature of meningiomas, significantly correlated with the malignancy scale, (ii) DNA fragmentation shows significant correlation with proliferation and inversely with BCL-2 expression; (iii) proliferation indices and frequencies of apoptosis/DNA fragmentation within meningioma subgroups corroborate the intermediate biological position of the atypical meningioma between classical and malignant meningiomas.     

Chromosomal losses and gains in meningiomas: Comparative genomic hybridization (CGH) study of the whole genome

Abstract

We investigated chromosomal aberrations in meningiomas using newly developed comparative genomic hybridization (CGH) technique and compared the results with the proliferating potential of the tumors. This technique permits the entire genome to be surveyed in one session of experiments. Our results revealed chromosomal aberrations in 5 out of 10 (50%) of the tumor samples studied. Losses of the distal parts of chromosome 1p (5 out of 10) and 22q (3 out of 10) were the two most frequent chromosomal aberrations. Losses and/or gains in other regions were only sporadic. The MIB-1 staining indices (MIB-511 %) were 1.9 ± 0.9% (mean ± SD) in benign (n = 8)1 4.5% in atypical (n = 1)1 and 11.7% in anaplastic (n = 1) meningiomas. The comparison of MIB-51 between the tumors with (2.3 ± 0.6%) and without (7.6 ± 0.3%) chromosomal aberrations demonstrated a trend towards an increased MIB-51 in meningiomas with chromosomal aberrations (p < 0.07) by unpaired 5tudent1s t-test. This study suggests that alterations in chromosomes 1p and 22q could be a primary focus of further detailed assessment of tumorigenesis and in understanding the biological behavior of meningiomas. [Neural Res 1998; 20: 612-616]     

Diagnostic validity of the Ki-67 labeling index using the MIB-1 monoclonal antibody in the grading of meningiomas

BACKGROUND: About 10% of meningiomas behave aggressively and are graded atypical or malignant with important therapeutic and prognostic implications. Routine histological parameters are inconsistent in the assessment of their aggressive behavior. AIMS: The aim of this study was to find a threshold level of the MIB-1 labeling index (MIB-1 LI) with the highest diagnostic validity in predicting histological atypia in a meningioma. SETTING AND DESIGN: This was a retrospective study of all atypical and malignant meningiomas diagnosed at our center between January 1995 and June 2000 and which were identified from the General Pathology Registry. MATERIAL AND METHODS: These meningiomas were assessed histologically with respect to the individual criteria of atypia. They were categorized according to the WHO 2000 classification as benign, atypical and anaplastic meningiomas, WHO Grades I, II and III respectively and by immunohistochemical analysis using the MIB-1 monoclonal antibody. STATISTICAL ANALYSIS: The diagnostically useful cut-off level for the prediction of atypia was estimated by calculating the sensitivity and specificity of the MIB-1 LI at various levels and a receiver operated characteristic (ROC) analysis was performed. The correlation between the individual histological parameters was studied and the MIB-1 LI was obtained using Fisher's exact test. RESULTS: Of the 40 meningiomas studied 21 were benign, 16 atypical and 3 anaplastic. Atypical tumors had a higher MIB-1 LI than benign tumors, with diagnostic validity highest at a threshold of 7%, with a sensitivity of 0.86 and a specificity of 0.93, giving a likelihood ratio of 17. The MIB-1 LI correlated well with mitotic activity and the other individual criteria in the WHO 2000 definition of atypia in a meningioma. MIB-1 LI did not, however, correlate well with brain invasion. CONCLUSION: The MIB-1 LI has the highest validity in the diagnosis of atypia in meningiomas at a threshold level of 7%. The MIB-1 LI used in conjunction with histological features can help in making a recommendation regarding potentially aggressive behavior in meningiomas.     

Correlation between histological grade and MIB-1 and p53 immunoreactivity in meningiomas

OBJECTIVE: Meningiomas for the most part are slow-growing benign tumors, but complete removal can be difficult and recurrence is an issue. The aim of this study was to re-evaluate tumors diagnosed as meningioma previously in our hospital, according to the latest World Health Organization classification. We also examined the relationships among parameters such as brain invasion, histological grade and Ki-67 and p53 expression in these tumors. MATERIALS AND METHODS: Meningioma biopsy specimens numbering 60 (48 grade I, 11 grade II, and 1 grade III tumors) were examined immunohistochemically using monoclonal antibodies for Ki-67 (MIB-1) and p53 protein. The MIB-1 labeling index (LI) for each tumor was calculated as a percentage based on the number of stained cells per total cells counted. The level of p53 expression in each sample was semiquantatively evaluated as < 1%, 1 - 10%, 10 - 70%, or > 70%. Any value > 1% was accepted as presence of p53 expression. RESULTS: Of the 60 meningiomas, 7 (11.7%) exhibited brain invasion. The mean MIB-1 LI values for the grade I and grade II tumors were 1.1% and 2.3%, respectively. The corresponding levels of p53 protein expression in these groups were 54.1% and 72.7%. The MIB-1 LI and the level of p53 expression in the one grade III meningioma were 6.7% and 10 - 70%, respectively. Histological grade was significantly correlated with MIB-1 LI and with p53 expression (p < 0.01 for both). Brain invasion was not correlated with histological grade, MIB-1 LI, or p53 expression. CONCLUSION: The results indicate that MIB-1 LI and p53 protein expression are good indicators of histological grade in meningioma and may be particularly valuable for distinguishing borderline atypical meningiomas. The number of cases was limited, but the findings also suggest that brain invasion is a prognostic parameter independent of grade, MIB-1 LI and p53 expression.     

Prognostic significance of Ki-67/MIB-1 proliferation index in meningiomas

Even though tumor grade, subtype, and extent of resection are strong prognostic factors in human meningiomas, the growth of this tumor is still unpredictable, and additional prognostic markers are needed. Thus, immunohistochemical determination of proliferative activity using the Ki-67 equivalent antibody MIB-1 has gained increased attention. However, the reported prognostic significance of this marker in meningiomas is not fully clarified. The aim of this study was to investigate the prognostic role of MIB-1 proliferation index (PI) in a series of meningiomas comprising 23 benign, 17 atypical, and 9 anaplastic tumors. MIB- 1 PI increased with increasing tumor grade and discriminated significantly benign from atypical and anaplastic meningiomas whereas no difference was found between the latter two grades. However, due to the considerable overlap of PI values between the various grades, one should be circumspect before using this criterion for tumor grading. Furthermore, MIB-1 PIs were significantly higher in recurrent tumors compared with non-recurrent and a reliable MIB-1 PI cut-off value of 10% was established. This value, however, cannot automatically be adapted by other laboratories and must be regarded just as a guideline. In conclusion, MIB-1 PI appears as an important prognostic factor and should be used in combination with traditional histological criteria for malignancy in order to identify meningiomas with increased risk of recurrence.     

Chromosome 1p and 14q FISH analysis in clinicopathologic subsets of meningioma: diagnostic and prognostic implications

The second most frequently reported genetic abnormalities in meningiomas after 22q loss are deletions of 1p and 14q. To assess the potential diagnostic and prognostic utility of these chromosomal alterations, we studied 180 well-characterized meningiomas using dual-color fluorescence in situ hybridization (FISH) with DNA probes localized to 1p32, 1p36, 14q13, and 14q32. Our cohort consisted of 77 benign (grade I), 74 atypical (grade II), and 29 anaplastic (grade III) meningiomas. Benign and atypical meningiomas were further stratified into subsets of recurring (despite gross total resection) vs non-recurring (at least 10 yr of follow-up) and mitotically active vs brain invasive subsets, respectively. Losses of 1p and 14q losses were identified in 23% and 31% of benign, 56% and 57% of atypical, and 75% and 67% of anaplastic meningiomas, respectively (p < 0.001 for 1p; p = 0.004 for 14q). Combined 1p/14q deletions were encountered in 7% benign. 39% atypical, and 63% anaplastic meningiomas (p < 0.001). Benign non-recurring meningiomas were less likely to harbor 14q deletions than recurring examples (17% vs 50%, p = 0.013). There was a trend for anaplastic meningiomas with 14q deletions and atypical meningiomas with combined 1p/14q deletions to have poorer overall survivals, though neither reached statistical significance. We conclude that 1p and 14q deletions are highly associated with increasing histologic grade and play an important role in meningioma tumor progression. Furthermore, 14q FISH analysis may aid in assessing recurrence risk in histologically benign meningiomas.     

Aggressive phenotypic and genotypic features in pediatric and NF2-associated meningiomas: a clinicopathologic study of 53 cases

Pediatric and NF2-associated meningiomas are uncommon and poorly characterized in comparison to sporadic adult cases. In order to elucidate their molecular features, we analyzed MIB-1, progesterone receptor (PR), NF2, merlin, DAL-1, DAL-1 protein, and chromosomal arms 1p and 14q in 53 meningiomas from 40 pediatric/NF2 patients using immunohistochemistry and dual-color fluorescence in situ hybridization (FISH). Fourteen pediatric (42%) patients, including 5 previously undiagnosed patients, had NF2. The remaining 19 (58%) did not qualify. All 7 of the adult patients had NF2. Meningioma grading revealed 21 benign (40%), 26 atypical (49%), and 6 anaplastic (11%) examples. Other aggressive findings included high mitotic index (32%), high MIB-1 LI (37%), aggressive variant histology (e.g. papillary, clear cell) (25%), brain invasion (17%), recurrence (39%), and patient death (17%). FISH analysis demonstrated deletions of NF2 in 82%, DAL-1 in 82%, 1p in 60%, and 14q in 66%. NF2-associated meningiomas did not differ from sporadic pediatric tumors except for a higher frequency of merlin loss in the former (p = 0.020) and a higher frequency of brain invasion in the latter (p = 0.007). Thus, although pediatric and NF2-associated meningiomas share the common molecular alterations of their adult, sporadic counterparts, a higher fraction are genotypically and phenotypically aggressive. Given the high frequency of undiagnosed NF2 in the pediatric cases, a careful search for other features of this disease is warranted in any child presenting with a meningioma.     

Merlin, DAL-1, and progesterone receptor expression in clinicopathologic subsets of meningioma: a correlative immunohistochemical study of 175 cases

The molecular pathogenesis of meningiomas is poorly characterized. Loss of NF2 (merlin) expression has been reported in 30%-80% of all sporadic meningiomas. Recently, we found that loss of expression for a second Protein 4.1-family tumor suppressor. DAL-1, is also common. A biologically important role for progesterone receptor (PR) has also been proposed based on its reported inverse relationship with tumor grade. In order to better define the pathogenetic roles of these proteins, we studied the merlin, DAL-1, and PR immunoprofiles in 175 fully characterized meningiomas, including nonrecurring versus recurring benign, proliferative versus brain invasive atypical and anaplastic subtypes. Loss of expression for either Protein 4.1-family tumor suppressor (merlin or DAL-1) was almost universal (92%), with combined losses being common (58%). Individually, absence of merlin or DAL-1 protein was detected in 74% and 76% respectively, with no significant differences among the 5 subsets. PR immunoreactivity was commonly associated with retained DAL-1 expression (p < 0.001) and with tumor grade, with 51% of benign, 21% of atypical, and 11% of anaplastic tumors staining positive (p < 0.001). We conclude that PR immunohistochemistry may have diagnostic utility in meningothelial neoplasms. Protein 4.1-family tumor suppressor losses are likely important early events in meningioma pathogenesis, whereas PR expression is associated with benignity.     

Localization of the neuronal class III beta-tubulin in oligodendrogliomas: comparison with Ki-67 proliferative index and 1p/19q status

The class III beta-tubulin isotype (betaIII) is widely regarded as a neuronal marker in development and neoplasia. Whereas the expression of betaIII in neuronal/neuroblastic tumors is differentiation-dependent, the aberrant expression of this cytoskeletal protein in astrocytomas is associated with an ascending gradient of malignancy. To test the generality of this observation we have compared the immunoreactivity (IR) profiles of the betaIII isotype with the Ki-67 nuclear antigen proliferative index in 41 archival, surgically excised oligodendrogliomas (32 classical [WHO grade II] and 9 anaplastic [WHO grade III]). Seventeen of 41 tumors were examined by quantitative microsatellite analysis for loss of 1p and/or 19q. Minimal deletion regions were defined on 1p (D1S468, D1S214) and 19q (D19S408, D19S867). Three of 10 classical oligodendrogliomas had combined 1p/19q loss, while 2 exhibited loss of either 1p or 19q. Three of 7 anaplastic tumors had combined 1p/19q loss. BetaIII IR was present in all tumors, but was significantly greater in the anaplastic (median labeling index [MLI] 61%, interquartile range [IQR] 55%-64%) as compared with the classical variants (MLI, 19%, IQR, 11-36%) (p < 0.0001). A highly significant relationship was found to exist between betaIII and Ki-67 LIs (betaIII, p < 0.0001 and Ki-67, p < 0.0001. r = 0.809). BetaIII localization delineated hitherto understated unipolar or bipolar tumor phenotypes with growth cones and leading cell processes resembling migrating oligodendrocyte progenitor cells. Codistribution of betaIII and GFAP IR was present in "gliofibrillary" tumor areas. Synaptophysin IR was detected in rare tumor cells (mean LI, 0.7%), and only in 4/41 samples (10%), denoting a lack of relationship between betaIII and synaptophysin expression. No significant differences in betaIII LIs were observed in tumors with 1p and/or 19q loss as compared to those with 1p/19q intact status. Increased betaIII IR in oligodendrogliomas is associated with an ascending degree of malignancy and thus is a potentially useful tumor marker. However, the significance of high betaIII LIs in low-grade oligodendrogliomas with respect to prognostic and predictive value requires further evaluation. Class III beta-tubulin expression in oligodendrogliomas should not be construed as a priori evidence of divergent neuronal differentiation.     

The expression of cell cycle regulatory proteins in oligodendroglial tumors

Oligodendroglial tumors are mainly classified histologically into 2 types of tumors--oligodendrogliomas and oligoastrocytomas--whether the tumor includes astrocytic component or not, and these are, respectively, divided histologically into 2 different malignant groups, low-grade (WHO grade II) and high-grade or anaplastic (WHO grade III). In this study, we investigated the expression of the cell cycle-related proteins and analyzed the relationship between the labeling index (LI: the percentage of positive nuclei) of these proteins and 2 histopathological phenotypes, grade and prognosis. Forty-four specimens were examined, including 11 oligodendorogliomas (0), 5 oligoastrocytomas (OA), 18 anaplastic oligodendrogliomas (aO) and 10 anaplastic oligoastrocytomas (aOA), according to the WHO classification. Of these, 19 specimens were obtained from recurrent tumors of 8 cases. The mean LI of all the investigated proteins between O and OA, and aO and aOA showed no significant differences. The mean MIB-1 LI, pRb LI, p53 LI and p14 LI of GIII were significantly higher than GII, while the mean p27 LI of GIII was significantly lower than GII. In the recurrent cases, we noted correlations between the disease-free period and MIB-1 LI (inverse), p27 LI and p14 (inverse). Significant correlations were noted between MIB-1 LI and pRb LI, MIB-1 LI and cycD1 LI, MIB-1 LI and p27 LI (inverse), pRb LI and cycD1 LI, cycD1 LI and cdk4 LI and pRb LI and p27 LI (inverse) in the pRb/cycD1-cdk4/p27 pathway, and between MIB-1 LI and p53 LI, MIB-1 LI and p14 LI, p53 LI and p14 LI, p53 LI and MDM2 LI and MDM2 LI and p14 LI in the p53/MDM2/p14 pathway. In conclusion, both pRb/cycD1-cdk4/p27 and p53/N4DM2/p14 pathways correlate with malignant progression, and MIB-1 LI, pRb LI, p27 LI, p53 LI and p14 LI reflect the histopathological malignancy of oligodendroglial tumors. MIB-1 LI, pRb LI and p27 LI are especially useful as indicators of malignancy of oligodendroglial tumors.     

Clinical and histological features of multiple meningiomas compared with solitary meningiomas

Between 1991 and 2002, 456 patients with an intracranial meningioma were treated. Thirty-nine of these had more than one meningioma (8.6%). The mean age was 58 years (27-85 years). Sex distribution was 8.8:1 (35 female, four male). There was no associated spinal meningioma. No patient had neurofibromatosis. In 19 patients all meningiomas were removed. Twelve showed the same histology, seven had different histological features. In the remaining 20 patients only the symptomatic meningioma was removed. Recurrences occurred in 11 patients (28.2%). Six patients died during follow-up. Multiple meningiomas have their own clinical features. Besides a high female preponderance, PR expression was stronger in multiple meningiomas than in solitary meningiomas while p53 status and MIB-1 LI were similar between the two groups. Progesterone receptor, p53 status and MIB-1 LI were valuable markers for predicting a patient's outcome in multiple meningiomas. The number of meningiomas is growing in patients with recurrent meningiomas.     

Immunohistochemical analysis of cyclin A in astrocytic tumours

Cyclins are important regulators of the cell cycle; there is increasing evidence that some cyclins are positively involved in carcinogenesis. Amplification and translocation of the cyclin genes and overexpression of their mRNAs and proteins have been observed in a variety of tumours. We studied cyclin A protein in astrocytic tumours by immunohistochemical analysis. Immunohistochemistry with microwave antigen retrieval was carried out on formalin fixed, paraffin embedded material from 15 glioblastomas (WHO grade IV), 10 anaplastic astrocytomas (WHO grade III), seven diffuse low grade astrocytomas (WHO grade II) and nine pilocytic astrocytomas (WHO grade I) using antibodies against cyclin A and a proliferation marker MIB1. Staining for these antibodies was seen mainly in the tumour cell nuclei; 66% of all cases showing staining for cyclin A and 95% of all cases staining for MIB1. Mean labelling indices (LI) for cyclin A were higher in glioblastoma (mean LI-6.7) and anaplastic astrocytoma (mean LI-5.9) than low grade diffuse astrocytoma (mean LI-1.7) and pilocytic astrocytoma (mean LI −0.12), although there was no clear cut off point between the various tumour types. A good correlation was seen between labelling indices of cyclin A and MIB1 (Pearson correlation coefficient r =0.59, P <0.0001). Cyclin A is variably expressed in astrocytic tumours, either reflecting increased tumour proliferation (cyclin A being an integral component of the cell cycle), an alteration of its gene, protein upregulation or regulation of apoptosis. The genetic basis of expression of cyclin A in astrocytic tumours remains to be determined.     

Morphometrical analysis of nucleolin immunohistochemistry in meningiomas

Nucleolin (110 kDa) is a major nucleolar protein in eukaryotic cells and one of the nucleolar organizer region (NOR)-associated proteins. We studied immunohistochemically 32 cases of meningioma, using specific antisera against nucleolin, and analyzed various nucleolin parameters, such as the number of regions and the total area of nucleolin staining per nucleus. The mean number and area of nucleolin stainings per nucleus were compared with the histological malignancy and Ki-67/MIB-1 proliferation index; the correlation with parameters of silver-stained NOR (AgNOR) was also studied. The results showed that there were statistically significant differences in the mean number and area of nucleolin stainings per nucleus between meningiomas and other two groups, atypical and anaplastic meningiomas (P < 0.05), although there was no difference between atypical and anaplastic meningiomas. The mean number and area of nucleolin stainings per nucleus were correlated with the incidence of Ki-67 positivity and AgNOR area. In view of the technical problems inherent in AgNOR staining, immunohistochemistry for nucleolin may represent a more specific and reproducible means for NOR visualization and be a promising technique for assessing cell proliferation. Received: 4 September 1995 / Revised, accepted: 20 December 1995     

Evaluation of p53 protein expression and proliferative potential based on the MIB-1 positive index in astrocytic gliomas

Fifty-seven patients with infiltrative astrocytic gliomas, comprising 29 cases of glioblastoma, 13 cases of anaplastic astrocytoma and 15 cases of low-grade astrocytoma, were examined. In 12 cases of astrocytic glioma, the p53 gene mutation was investigated by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP). p53 overexpression was observed in 20 (35%) of the 57 patients with astrocytic gliomas. The occurrence of p53 overexpression was apparently correlated with the histological grading of the astrocytic gliomas. Of the 20 patients with glioblastoma who were less than 60 years old (mean age ± SD, 39.2 ± 15.0 years), 50% demonstrated p53 overexpression, whereas only 2 (22%) patients with glioblastoma who were more than 60 years old (mean age ± SD, 65.1 ± 5.8 years) had p53 overexpression. A substantial difference in survival associated with glioblastoma was noted between the p53-positive group (mean survival 28.9 months) and the p53-negative group (mean survival 11.3 months) based on Kaplan-Meier survival curves (P= 0.01). Even among patients with glioblastoma who were less than 60 years old, a better survival rate was recognized in those with p53 overexpression than in those without p53 (P= 0.03). The MIB-1 indices tended to increase with tumor malignancy, and a poor survival time was significantly associated with elevated values for the MIB-1 index. A substantial difference in survival between the two groups of patients who had MIB-1 indices of above 5% and below 5% was evident from the Kaplan-Meier survival curves (P= 0.04). The group that had no p53, and MIB-1 indices of above 5%, was found to show the malignant gliomas most frequently. Although most of the gliomas with p53 overexpression demonstrated MIB-1 indices of above 5%, there was no significant correlation between p53 protein expression and the MIB-1 index. Of the 12 patients with astrocytic glioma who were examined by PCR-SSCP, 3 (one glioblastoma and 2 anaplastic astrocytomas) revealed p53 gene mutation correlated with p53 (DO-7) overexpression.     

Loss of Heterozygosity at 1p, 7q, 17p, and 22q in Meningiomas

Objective

Allelic losses or loss of heterozygosity (LOH) at many chromosomal loci have been found in the cells of meningiomas. The objective of this study was to evaluate LOH at several loci of different chromosomes (1p32, 17p13, 7q21, 7q31, and 22q13) in different grades of meningiomas.

Methods

Forty surgical specimens were obtained and classified as benign, atypical, and anaplastic meningiomas. After DNA extraction, ten polymorphic microsatellite markers were used to detect LOH. Medical and surgical records, as well as pathologic findings, were reviewed retrospectively.

Results

LOH at 1p32 was detected in 24%, 60%, and 60% in benign, atypical, and anaplastic meningiomas, respectively. Whereas LOH at 7q21 was found in only one atypical meningioma. LOH at 7q31 was found in one benign meningioma and one atypical meningioma. LOH at 17p13 was detected in 4%, 40%, and 80% in benign, atypical, and anaplastic meningiomas, respectively. LOH at 22q13 was seen in 48%, 60%, and 60% in benign, atypical, and anaplastic meningiomas, respectively. LOH results at 1p32 and 17p13 showed statistically significant differences between benign and non-benign meningiomas.

Conclusion

LOH at 1p32 and 17p13 showed a strong correlation with tumor progression. On the other hand, LOH at 7q21 and 7q31 may not contribute to the development of the meningiomas.     

Immunocytochemical analysis of glucose transporter protein‐1 (GLUT‐1) in typical,brain invasive,atypical and anaplastic meningioma

Glucose transporter‐1 (GLUT‐1) is one of the major isoforms of the family of glucose transporter proteins that facilitates the import of glucose in human cells to fuel anaerobic metabolism. The present study was meant to determine the extent of the anaerobic/hypoxic state of the intratumoral microenvironment by staining for GLUT‐1 in intracranial non‐embolized typical (WHO grade I; n = 40), brain invasive and atypical (each WHO grade II; n = 38) and anaplastic meningiomas (WHO grade III, n = 6). In addition, GLUT‐1 staining levels were compared with the various histological criteria used for diagnosing WHO grade II and III meningiomas, namely, brain invasion, increased mitotic activity and atypical cytoarchitectural change, defined by the presence of at least three out of hypercellularity, sheet‐like growth, prominent nucleoli, small cell change and “spontaneous” necrosis. The level of tumor hypoxia was assessed by converting the extent and intensity of the stainings by multiplication in an immunoreactive score (IRS) and statistically evaluated. The results were as follows. (1) While GLUT‐1 expression was found to be mainly weak in WHO grade I meningiomas (IRS = 1–4) and to be consistently strong in WHO grade III meningiomas (IRS = 6–12), in WHO grade II meningiomas GLUT‐1 expression was variable (IRS = 1–9). (2) Histologically typical, but brain invasive meningiomas (WHO grade II) showed no or similarly low levels of GLUT‐1 expression as observed in WHO grade I meningiomas (IRS = 0–4). (3) GLUT‐1 expression was observed in the form of a patchy, multifocal staining reaction in 76% of stained WHO grade I‐III meningiomas, while diffuse staining (in 11%) and combined multifocal and areas of diffuse staining (in 13%) were only detected in WHO grades II and III meningiomas, except for uniform staining in angiomatous WHO grade I meningioma. (4) “Spontaneous” necrosis and small cell change typically occurred away from the intratumoral capillary network embedded within the pattern of GLUT‐1 staining. Taken together, GLUT‐1 staining cannot be applied as a substitute for histologic grading in order to predict tumor behavior. However, assessment of tumor hypoxia in association with “spontaneous” necrosis and foci of small cell change may substantially contribute to the neuropathologic diagnosis of WHO grades II and III meningioma.     

Metallothionein overexpression in human brain tumours

Metallothioneins (MTs) are metal binding proteins overexpressed in various human neoplasms which are associated with resistance to cytotoxic drugs. A series of 156 archival human brain tumours were investigated immunohistochemically for expression of MTs; these included 10 low-grade gliomas, 44 high-grade gliomas, 98 meningeal tumours (19 classical, 30 atypical, 38 anaplastic meningiomas, and 11 haemangiopericytomas or papillary meningiomas), and 4 other tumours. Low-grade gliomas showed heterogeneous MT expression; 32 high-grade gliomas (72.7%) showed MT expression of more than 25% of tumour cells without statistically significant differences between first operations and recurrent tumours. In 2 glioblastomas, the presence of MT was confirmed by Western blotting. The extent of MT immunoexpression showed a statistically significant inverse relationship to the degree of p53 immunoreactivity. In meningiomas, a tendency to a higher percentage of MT-expressing cells was observed from classical over atypical to anaplastic meningiomas, but these differences were not statistically significant. In conclusion, MT expression is present in a significant portion of, especially malignant, brain tumours and might be involved in their poor response to antineoplastic drugs. Received: 10 August 1995 / Revised: 15 February 1997, 14 April 1997 / Revised, accepted: 7 July 1997     

Significance of cyclin D1 expression in meningiomas: a preliminary study.

Forty-four evaluable patients with intracranial meningiomas were assessed for the expression of the cell-cycle regulator cyclin D1 and of proteins involved in proliferation and apoptosis such as PCNA, MIB-1, p53 and bcl-2. Analyses were carried out by western blot and immunohistochemistry after immediate processing of fresh tumor specimens. By western blot, expression of cyclin D1 significantly correlated with p53 (p=0.02) and with proliferative activity, as assessed by PCNA expression (p=0.0009). By immunohistochemistry, a significant relationship between cyclin D1 and the proliferation marker MIB-1 was confirmed (p=0.05), whereas significance with bcl-2 expression was not found (p=0.01). Moreover, although the association with tumor grade appeared of borderline statistical significance (p=0.07), all the grade II/III meningiomas showed increased expression of cyclin D1 and high proliferative activity. In conclusion, data from this preliminary study seem to suggest a potential value of the combined expression of cyclin D1 and proliferation indicators in defining subgroups of meningiomas with a more aggressive biological behavior.     

Pathodiagnostic parameters for meningioma grading

Meningiomas are usually slow-growing benign tumors, for which complete removal can be difficult and recurrence is an issue. In this study the relationship between pathodiagnostic parameters, histological grade, and MIB-1 monoclonal antibody expression in meningioma diagnosed over 10 years in Shohada Hospital, Tehran, was assessed. All cases were re-evaluated according to the latest World Health Organization (WHO) Classification. Between January 1997 and December 2006, a total of 4885 intracranial tumors were diagnosed at Shohada Hospital, 378 (7.74%) of which were meningiomas. All slides stained with hematoxylin and eosin were reviewed by two independent pathologists and all the diagnoses reconfirmed; histological anaplasia was classified according to the grading of the WHO Working Group 2000 as benign (Grade I), atypical with incipient signs of anaplasia (Grade II), or overtly anaplastic (Grade III). The mean age of patients with meningiomas was 49.11+/-12.99 years (range 6-78 years, median=50); females outnumbered males by a ratio of 1.7 to 1. Presenting symptoms were headache/vertigo (66.7%) and epilepsy (28.5%). Convexity meningiomas were most common, followed by meningiomas of the sphenoid ridge and cerebellopontine angle. There was no relationship between the location of the tumor and the histopathological features. The association between mitotic rate, increased cellularity, nucleo-cytoplasmic ratio, and sheet-like spreading was especially strong. Histopathological study of completely resected meningiomas showed that loss of architecture, frequent mitotic figures, a high cellularity, increased nucleo-cytoplasmic ratio, a prominent nucleolus, brain invasion, and necrosis were correlated with the grade of the meningiomas. Overall, the mitotic count was the most important marker for tumor grade.