原发性脑瘤的分子遗传学研究进展

［摘要］ 原发性脑瘤是发生于神经系统常见的疾病,高度恶性的胶质瘤占原发性脑瘤的40%,主要分为I型胶质母细胞瘤（继发性胶质母细胞瘤）和II型胶质母细胞瘤（原发性胶质母细胞瘤）,二者的产生有着不同的遗传学改变。I型胶质母细胞瘤的产生途径是从一种恶性程度较低的星形细胞瘤（II级,主要为p53基因突变和血小板来源的生长因子/受体过表达）至恶性的间变型星型细胞瘤（III级,主要为Rb基因突变,CDK4基因扩增,9p、11p、13q和19q的等位基因缺失）,再到胶质母细胞瘤（IV级,最常见的遗传学改变是7号和20号染色体的获得,10号染色体的丢失以及PTEN和LRRC4基因的缺失,PDGFα及其受体的过表达）的渐进的发展过程;而II型胶质母细胞瘤则是一种没有恶性程度渐进过程的原发性胶质母细胞瘤,表皮生长因子受体基因的扩增是最常见的遗传学改变。     

ATRX在胶质瘤诊断及患者预后评估中的应用北大核心CSCD

目的探讨中国成人幕上胶质瘤中ATRX和p53基因突变在胶质瘤诊断及预后评估中的指导价值。方法选择整合诊断为WHOⅡ级、Ⅲ级的星形细胞瘤,IDH突变型;弥漫性星形细胞瘤,IDH野生型;WHOⅡ级、Ⅲ级的少突胶质细胞瘤,IDH突变型伴1p／19q共缺失,合计83例。采用免疫组织化学染色法检测ATRX蛋白失表达及p53蛋白过表达情况。分析两者的相关性及其与患者总生存期的关系。结果WHOⅡ级、Ⅲ级星形细胞瘤,IDH突变型及WHOⅡ级、Ⅲ级少突胶质细胞瘤,IDH突变型伴1p／19q共缺失的病例中的ATRX失表达率为85．19％（23／27）和0（0／53,P〈0．01）。在ATRX失表达病例中69．57％（16／23）同时存在p53过表达,二者密切相关（P〈0．01）。生存分析结果提示存在ATRX失表达、p53阴性的患者的总生存期长（P=0．013）。结论ATRX基因突变是较低级别星形细胞起源肿瘤的分子遗传特征之一,可以协助p53用于星形细胞瘤的诊断。ATRX联合p53基因突变检测可用于指导胶质瘤的预后评估。     

SV40大T抗原在人脑肿瘤中与p53形成特异性复合物

目的 探讨SV40早期区域基因编码产物大T抗原（Tag) 表达及与抑癌蛋白p53的相互作用在人脑肿瘤发生发展中的意义。方法 采用免疫共沉淀及Western印迹法检测43例人脑肿瘤组织及5例正常人脑组织中Tag的表达，并对18例Tag阳性瘤组织检测Tag-p53复合物的存在。结果 Tag在5例室管膜瘤及2例脉络丛乳头状瘤中全部表达，垂体腺瘤（5／6）、星形胶质细胞瘤（7／10）、脑膜瘤（4／6）、多形性胶质母细胞瘤（3／5）及髓母细胞瘤（2／5）均有Tag的表达，3例少枝胶质细胞瘤、1例松果体瘤及5例正常人脑组织无Tag表达；检测18例Tag阳性瘤组织均发现Tag与p53形成特异性复合物。结论 在人脑肿瘤组织中Tag广泛表达，Tag可与p53形成特异性复合物，Tag-p53特异性复合物的形成导致p53失活，可能是SV40致人脑肿瘤发生的一个重要机理。     

少突胶质细胞瘤的分子遗传学、病理与临床预后分析

目的 探讨少突胶质细胞肿瘤遗传分子表型、病理和临床预后的关系。方法 对51例（对）少突胶质细胞肿瘤和外周血进行DNA的提取,变性梯度凝胶电泳（DGGE）和DNA测序检测抑癌基因TP53、PTEN／MMAC1和p18突变;多重PCR检测EGFR扩增、p16／CDKN2A和p18缺失;多因素分析预后和生存期。结果 26例少突胶质细胞瘤中TP53和p18突变各1例;未发现PTEN／MMAC1突变;19．2％EGFR扩增;27％p16／CDKN2A缺失。25例GBMO中TP53,p18和PTEN／MMAC1突变分别是24％、0和20％。44％EGFR扩增,48％p16／CDKN2A缺失。所有肿瘤均未见p18同源性缺失。结论 缺乏TP53和PTEN／MMAC1突变是少突胶质细胞肿瘤独特的分子特性。其恶化进展和生存期短与EGFR扩增密切相关。     

第5版WHO中枢神经系统肿瘤分类成人型弥漫性胶质瘤和局限性星形细胞胶质瘤解读

2021年第5版WHO中枢神经系统肿瘤分类首次将胶质瘤分为成人型和儿童型, 并根据肿瘤的生长浸润情况分为弥漫性和局限性。成人型胶质瘤和儿童型胶质瘤在临床病理特征、分子改变及预后等方面均有所不同。其中成人型弥漫性胶质瘤包括IDH突变型星形细胞瘤、IDH突变伴1p/19q联合缺失的少突胶质细胞瘤、IDH野生型胶质母细胞瘤3种主要类型。局限性星形细胞胶质瘤指的是相对局限的生长模式, 包括毛细胞型星形细胞瘤、具有毛样特征的高级别星形细胞瘤、多形性黄色星形细胞瘤、室管膜下巨细胞星形细胞瘤、脊索样胶质瘤、星形母细胞瘤伴MN1改变6种主要类型。本文就第5版WHO中枢神经系统肿瘤分类中关于成人型弥漫性胶质瘤和局限性星形细胞胶质瘤进行解读。     

67例颅内星形细胞肿瘤临床病理分析

目的：探讨颅内星形细胞肿瘤的组织类型、分级与复发、预后的关系。方法：对６７例颅内星形细胞肿瘤的临床和病理资源进行统计分析。结果：免疫组织化学标记能帮助鉴定组织类型和颅内星形细胞肿瘤的分化程度。间质性星形细胞瘤和胶质母细胞瘤其术后２年、５年的生存率偏低（Ｐ〈０．００５）。结论：间变性星形细胞瘤和肥胖细胞星形细胞瘤更具恶性,易复发。胶质母细胞瘤在颅内肿瘤中恶性程度最高,预后差。     

水通道蛋白1、5在星形细胞瘤中的表达变化

目的:观察水通道蛋白1、5(AQP1、5)在人不同病理级别星形细胞瘤组织中的表达差异,探讨星形细胞瘤增殖、生长的分子机制.方法:收集人各个病理级别星形细胞瘤标本55例,以肿瘤周围相对正常脑组织作为对照,采用H-E染色诊断分级,石蜡切片免疫组织化学、免疫印迹分析及逆转录聚合酶链式反应观察AQP1、5及其mRNA的表达变化.结果:与正常脑组织相比,人星形胶质瘤组织中AQP1及其mRNA表达上调,随着星形细胞瘤病理级别的升高,AQP1及其mRNA表达增强,胶质母细胞瘤组织表达最强烈;而AQP5及其mRNA仅在高恶性星形细胞瘤组织中表达增强.结论:AQP1在人星形细胞瘤组织中表达与其病理级别相关,而AQP5仅在人高恶性星形细胞瘤组织中表达增强,提示不同病理级别胶质瘤组织中AQP的表达规律不尽相同.     

胶质瘤中失调的microRNA及相关基因研究进展

胶质瘤是一种常见的脑肿瘤,发生于神经外胚层。按细胞种类分,胶质瘤的主要类型有星形胶质细胞瘤、少突胶质细胞瘤和胶质母细胞瘤。2007年,世界卫生组织按胶质瘤的恶性程度和预后的好     

星形细胞肿瘤中PTEN蛋白表达及与微血管密度的相关性

目的 :研究不同恶性程度星形细胞肿瘤中PTEN蛋白的表达及与肿瘤微血管密度 (MVD)之间的相关性。方法 :应用免疫组织化学S P法检测 72例星形细胞肿瘤和非肿瘤脑组织中PTEN蛋白的表达并对肿瘤MVD计数 ,分析其意义及两者间的相关性。结果 :PTEN阳性染色主要定位于细胞质中 ,肿瘤总阳性率为 5 4 17% (39/ 72 ) ,其中Ⅱ、Ⅲ、Ⅳ级者PTEN阳性表达率分别为 81 82 % (18/ 2 2 )、42 86 % (15 / 35 )和 37 5 0 % (6 / 15 )。星形细胞瘤PTEN表达率明显高于间变性星形细胞瘤和多形性胶质母细胞瘤 (P <0 0 1) ;星形细胞肿瘤MVD计数 ,72例肿瘤平均MVD为 38 2 2 ,其中Ⅱ、Ⅲ、Ⅳ级者MVD分别为2 8 81± 9 42、41 17± 13 96和 5 3 11± 15 85 ,肿瘤组各级别间差异均有显著性 (P <0 0 1) ;星形细胞瘤以窦状扩张型血管、间变性星形细胞瘤以芽状或条索状血管为主 ,而多形性胶质母细胞瘤部分以球状血管丛为特征 ;PTEN蛋白的表达与肿瘤中MVD呈负相关 (r =- 0 5 11,P <0 0 1)。结论 :PTEN基因突变或缺失在星形细胞肿瘤的发生发展中可能起重要作用 ,与肿瘤恶性分化程度密切相关 ;PTEN表达的检测结合MVD与形态的测定有助于提高评估患者术后生存的准确性     

少突胶质细胞瘤染色体1p/19 q杂合性缺失与p53蛋白表达的相关性研究

目的 探讨少突胶质细胞瘤染色体1p/19q杂合性缺失及p53蛋白的表达情况,与星形细胞起源的肿瘤进行比较研究并探讨其意义.方法 选择2004-2005年间,经病理组织学诊断为不同类型和级别的胶质瘤合计191例,包括:WHOⅡ级少突胶质细胞瘤116例,其中30例为新鲜组织;间变性少突胶质细胞瘤45例和不同级别星形细胞起源的肿瘤石蜡组织30例;采用PCR-微卫星技术检测染色体1p/19q杂合性缺失情况;采用免疫组织化学方法 对184例胶质瘤石蜡切片p53蛋白表达情况进行半定量分析.结果 86例WHO Ⅱ级少突胶质细胞瘤石蜡标本染色体1p缺失率为69.8%(60/86)、19q缺失率为64.0%(55/86)、1p/19q联合缺失率为57.0%(49/86);45例间变性少突胶质细胞瘤中,1p缺失率为71.1%(32/45)、19q缺失率为60.0%(27/45)、1p/19q联合缺失率为55.6%(25/45);两种级别间差异无统计学意义(P>0.05).30例WHO Ⅱ级少突胶质细胞瘤新鲜标本染色体1p缺失率为70.0%(21/30)、19q缺失率为63.3%(19/30)、1p/19q联合缺失率为60.0%(18/30),与石蜡标本的缺失率比较差异无统计学意义(P>0.05).30例星形细胞起源的肿瘤染色体对应三种缺失率分别为23.3%(7/30)、33.3%(10/30)及20.0%(6/30),与少突胶质细胞瘤差异有统计学意义(P<0.05).86例WHO Ⅱ级少突胶质细胞瘤中,仅7例有p53蛋白阳性表达(占8.1%);45例间变性少突胶质细胞瘤中,有14例呈阳性表达(31.1%),两者差异有统计学意义(P=0.007).少突胶质细胞瘤p53蛋白阳性表达明显低于星形细胞起源的肿瘤(P=0.001).在间变性少突胶质细胞瘤中,染色体1p/19q杂合性缺失与p53蛋白阳性表达呈负相关(P<0.05).结论 石蜡和新鲜组织均可用于染色体1p/19q杂合性缺失的检测.在间变性少突胶质细胞瘤中,染色体1p/19q杂合性缺失与p53蛋白阳性表达呈负相关.检测少突胶质细胞瘤染色体1p/19q杂合性缺失和p53蛋白表达,对提高病理诊断的精确性、指导治疗及预后判断具有重要意义.     

Analysis of 2 antiapoptotic factors in gliomas: bcl-2 overexpression and p53 mutations

BACKGROUND: p53 mutations and immunoreactivity have been described in human gliomas. During the past few years, some authors have found bcl-2 overexpression in astrocytomas, although their correlation with histological grade is a matter of disagreement. A relation between bcl-2 overexpression and p53 immunoreactivity has also been suggested. OBJECTIVES: To analyze the frequency of presentation of bcl-2 and p53, their clinicopathologic implications, and their possible coexpression. METHODS: We studied p53 and bcl-2 with immunohistochemical and molecular methods in 61 gliomas (including 21 astrocytomas, 9 anaplastic astrocytomas, 29 glioblastomas, 1 oligodendroglioma, and 1 mixed glioma). RESULTS: We discovered a high level of bcl-2 overexpression (57%). Overexpression of bcl-2 can be an early event in gliomas tumorigenesis, although no correlation was found with any of the clinicopathologic parameters studied. p53 mutations were present in a small proportion of gliomas (17%). p53 immunoreactivity was present in 34 cases (57%), and it was related to histological grade and a supratentorial location. A high percentage of tumors (26 cases, 42%) presented p53 immunoreactivity without p53 mutations. CONCLUSIONS: Since there was no relation between bcl-2 overexpression and p53 mutations or p53 immunoreactivity, both factors may not act together in the genesis and evolution of gliomas.     

Neural cell adhesion molecule L1 in gliomas: correlation with TGF-beta and p53.

AIMS: To assess immunohistochemically whether the neural cell adhesion molecule L1, which is a member of the immunoglobulin superfamily and has been shown recently to be a stimulating factor for glioma migration, is expressed in glioma tissues, and to investigate factors that can regulate this expression. METHODS: Twenty seven glioma tissue specimens including 13 glioblastomas, seven anaplastic astrocytomas, and seven astrocytomas were examined. Immunohistochemical analyses of L1, p53, and transforming growth cell factor beta (TGF-beta) were performed on each tumour using both polyclonal and monoclonal antibodies. RESULTS: Nine (33%) specimens (six glioblastomas and three anaplastic astrocytomas) had L1 positive immunostaining. p53 positive staining was detected in 10 (43%) of 23 glioma specimens (seven glioblastomas and three anaplastic astrocytomas). TGF-beta positive immunostaining was observed in 12 (52%) of the 23 glioma specimens (six glioblastomas, four anaplastic astrocytomas, and two astrocytomas). There was a statistical correlation between both p53 and L1 expression and TGF-beta and L1 expression. No such correlation was found between p53 and TGF-beta expression. CONCLUSIONS: These results suggest that mutation of the p53 gene or expression of TGF-beta may upregulate the expression of the L1 gene, thus resulting in high grade migration of glioma cells.     

Genetic alterations in pediatric high-grade astrocytomas

High-grade astrocytomas are tumors that are uncommon in children. Relatively few studies have been performed on their molecular properties and so it is not certain whether they follow different genetic pathways from those described in adult diffuse astrocytomas. In this study, we evaluated 24 pediatric high-grade astrocytomas (11 anaplastic astrocytomas and 13 glioblastomas) all of which were sporadic and primary. We studied mutations of p53, phosphatase and tensin homolog (PTEN), loss of heterozygosity (LOH) of chromosomes 17p13, 9p21 and 10q23-25, amplification of epidermal growth factor receptor (EGFR), and overexpression of EGFR and p53 protein. In addition, we searched for microsatellite instability (MSI) by using MSI sensitive and specific microsatellite markers. p53 mutations were found in 38% (9/24) of the high-grade astrocytomas and all brain stem tumors except 2 (71%, 5/7) had p53 mutations. PTEN mutations were found in 8% (2/24) of high-grade astrocytomas. However, no EGFR amplification was found in any of them. LOH was found at 17p13.1 in 50% (3/6 informative tumors), 9p21 in 83% (5/6 informative tumors), and 10q23-25 in 78% (7/9 informative tumors). Four tumors showed MSI, and 2 of them that showed widespread MSI were regarded as tumors with replication error (RER+) phenotype. All 4 tumors with MSI showed concurrent LOH of 9p21 and 10q23-25. Combining gene alterations, LOH, MSI, and gene mutations, inactivation of both alleles of PTEN and p53 was found in 57% (4/7 informative tumors) and 50% (3/6 informative tumors) of the cases respectively. We conclude that development of pediatric high-grade astrocytomas may follow pathways different from the primary or secondary paradigm of adult glioblastomas. In a subset of these tumors, genomic instability was also implicated.     

Distinct patterns of deletion on 10p and 10q suggest involvement of multiple tumor suppressor genes in the development of astrocytic gliomas of different malignancy grades

Deletions of chromosome 10 are the most frequent genetic abnormality in glioblastomas. Several commonly deleted regions have been proposed; however, they are not coincident. We have deletion mapped chromosome 10 in 198 astrocytic gliomas using 53 microsatellite markers. Two commonly deleted regions on 10p were identified, one of which lies between D10S594 and D10S559 and the other between D10S1713 and D10S189. Most of 10q deletions were large and included a region distal to D10S554. Four glioblastomas of 122 had patterns suggestive of homozygous deletions at D10S541, a locus close and distally located to the PTEN/MMAC1 gene. Losses of alleles were found not only in glioblastomas (93%) but also in anaplastic astrocytomas (66%) and in astrocytomas (35%). Most glioblastomas lost one entire chromosome 10, while astrocytomas preferentially lost only 10p. The data suggest that a number of tumor suppressor genes on chromosome 10, in addition to PTEN/MMAC1, may be associated with astrocytic glioma development. Genes Chromosomes Cancer 22:9–15, 1998. © 1998 Wiley-Liss, Inc.     

Clinical evidence of distinct subgroups of astrocytic tumors defined by comparative genomic hybridization

In astrocytic tumors, the relationship between genetic pathways and patients' prognoses has not been fully investigated. In our studies of astrocytic tumors using comparative genomic hybridization, the presence of 8q gain was mutually exclusive of 7p gain or amplification. In this study, 45 cases of astrocytic tumor were divided into 3 groups: those with 7p gain, cases with 8q gain, or those with neither; and their clinical course, p53, and epidermal growth factor receptor (EGFR) expressions and proliferative activity were then compared. Of the cases examined, 17 (12 glioblastomas and 5 anaplastic astrocytomas) showed 7p gain. Eleven cases (5 glioblastomas, 2 anaplastic, and 4 low-grade astrocytomas) showed 8q gain. p53 accumulation was observed more frequently in cases with 8q gain than in those with 7p gain. Astrocytic tumors with 8q gain occurred more frequently in younger patients than those with 7p gain. Kaplan-Meier survival rate analysis showed higher survival rates in patients with 8q gain than in those with 7p gain. This tendency also was observed when only patients with malignant glioma were included in the survival analysis. Our results provide evidence for distinct clinical manifestations in astrocytic tumors with 8q and 7p gain.     

Phenotype vs genotype in the evolution of astrocytic brain tumors

Astrocytic brain tumors are the most frequent human gliomas and they include a wide range of neoplasms with distinct clinical, histopathologic, and genetic features. Diffuse astrocytomas are predominantly located in the cerebral hemispheres of adults and have an inherent tendency to progress to anaplastic astrocytoma and (secondary) glioblastoma. The majority of glioblastomas develop de novo (primary glioblastomas), without an identifiable less-malignant precursor lesion. These subtypes of glioblastoma evolve through different genetic pathways, affect patients at different ages, and are likely to differ in their responses to therapy. Primary glioblastomas occur in older patients and typically show epidermal growth factor receptor (EGFR) overexpression, PTEN mutations, p16 deletions, and, less frequently, MDM2 amplification. Secondary glioblastomas develop in younger patients and often contain TP53 mutations as their earliest detectable alteration. Morphologic variants of glioblastoma were shown to have intermediate clinical and genetic profiles. The giant cell glioblastoma clinically and genetically occupies a hybrid position between primary (de novo) and secondary glioblastomas. Gliosarcomas show identical gene mutations in the gliomatous and sarcomatous tumor components, which strongly supports the concept that there is a monoclonal origin for gliosarcomas and an evolution of the sarcomatous component due to aberrant mesenchymal differentiation in a highly malignant astrocytic neoplasm.     

Overexpression of the EGF Receptor and p53 Mutations are Mutually Exclusive in the Evolution of Primary and Secondary Glioblastomas

Glioblastoma multiforme, the most malignant human brain tumor, may develop de nova (primary glioblastoma) or through progression from low-grade or anaplastic astrocytoma (secondary glioblastoma). We present further evidence that primary and secondary glioblastomas constitute distinct disease entities which develop through the acquisition of different genetic alterations. We analyzed p53 mutations, p53 protein accumulation and epidermal growth factor receptor (EGFR) overexpression in 49 biopsies classified as primary or secondary glioblastorna according to clinical and histopathologic criteria. Patients with primary glioblastoma were selected on the basis of a clinical history of less than 3 months and histopathologic features of glioblastoma at the first biopsy 119 cases; mean age, 55 years). The diagnosis of secondary glioblastomas required at least two biopsies and clinical as well as histologic evidence of progression from low grade or anaplastic astrocytoma (30 cases; mean age, 39 years). DNA sequence analysis showed that p53 mutations were rare in primary glioblastomas (11%) while secondary glioblastomas had a high incidence of p53 mutations (67%), of which 90% were already present in the first biopsy. The incidence of p53 protein accumulation (nuclear immunoreactivity to PAb 1801) was also lower in primary (37%) than in secondary glioblastornas (97%). In contrast, immunoreactivity for the EGF receptor prevailed in primary glioblastornas (63%) but was rare in secondary glioblastornas (10%). Only one out of 49 glioblastomas showed EGFR overexpression and a p53 mutation. These data indicate that overexpression of the EGF receptor and mutations of the p53 tumor suppressor gene are mutually exclusive events defining two different genetic pathways in the evolution of glioblastoma as the common phenotypic endpoint.     

ATRX in Diffuse Gliomas With its Mosaic/Heterogeneous Expression in a Subset

This study aims (1) to evaluate ATRX expression in different grades and subtypes of gliomas and correlate with other hallmark genetic alterations, (2) to identify and characterize mosaic/heterogeneous staining in gliomas in terms of mutation status. One hundred seventy six cases of glioma were assessed for ATRX immunohistochemistry and subdivided into positive, negative and mosaic/heterogeneous staining patterns. Five cases with heterogeneous staining were further subjected to next generation sequencing. Higher frequency of ATRX immune‐negativity was detected in grade II/III astrocytic, oligoastrocytic tumors and secondary glioblastomas (GBMs), while infrequent in primary GBMs and rare in oligodendrogliomas. Loss of expression was significantly associated with IDH1 and/or TP53 mutation, while mutually exclusive with 1p/19q codeletion. Mosaic/heterogeneous staining was detected exclusively in GBMs (21.2%). Two different types of mosaic staining were identified (1) Admixture of positive and negative nuclei or intermixed mosaic and (2) Separate fragments with positive and negative/intermixed mosaic staining. ATRX mutation was identified in 2/5 (40%) cases with mosaic staining while one case showed DAXX mutation. All these cases were characterized by distinctly separate immune‐negative and positive/intermixed foci. Hence, it is suggested that cases with heterogeneous staining (especially those with distinctly negative fragments) should be subjected to mutation analysis.