Trk A, B, and C are commonly expressed in human astrocytes and astrocytic gliomas but not by human oligodendrocytes and oligodendroglioma

Neurotrophins regulate the proliferation and differentiation of neurons in the central nervous system via a family of specialized receptors, including TrkA, TrkB, and TrkC. As little is known about their expression or potential role in human glial tissues and glial tumors, we undertook an immunohistochemical analysis of human glia, glioma tissues and cell cultures of glial tumors to characterize the expression of Trk family members (full-length TrkA, TrkB, the truncated form of TrkB, and TrkC). In normal human brain Trk A, B, and C immunoreactivity was found in neurons and some weak staining was also seen astrocytes. No Trk expression was seen on oligodendrocytes. Strong reactivity was seen in reactive astrocytes in a glial scar. In a total of 34 glioma tissue specimens, which included 16 astrocytic tumors (4 low-grade astrocytomas and 12 glioblastomas multiforme) and 15 oligodendrogliomas (8 low-grade and 7 anaplastic) as well as 3 oligoastrocytomas (WHO grade II), TrkA, B, and C immunoreactivity was observed exclusively in specimens from astrocytic gliomas (16/16), but not in any of the oligodendrocytic gliomas (0/15). In the oligoastrocytomas, staining was restricted to the astrocytic component. In the astrocytoma and oligodendroglioma specimens, Trk A, B, and C immunoreactivity was also seen in the surrounding reactive astrocytes. Trk expression was independent of age, sex or histological grade of the investigated tumors. In six primary cell cultures, one derived from human astrocytes and five established from malignant astrocytomas, only TrkA immunoreactivity could be detected, while TrkB (both full-length and truncated isoforms) and TrkC were absent. The TrkA expression in primary cell cultures decreased with continuous cell passaging, and no Trk could be detected in established cell lines derived from glioblastoma. In conclusion, our data suggest that in human glial tissues Trk A, B, and C may be expressed in a lineage-restricted manner, thereby distinguishing between astrocytes and oligodendrocytes in a marker-like fashion. Trk expression, like GFAP expression appears to be increased in activated (reactive)/ neoplastic astrocytes. Received: 15 January 1998 / Revised, accepted: 27 March 1998     

Expression of tyrosine kinases FAK and Pyk2 in 331 human astrocytomas

The progression of malignancy from astrocytomas to glioblastomas remains clinically as well as histopathologically unpredictable. The focal adhesion kinase (FAK) and the proline-rich tyrosine kinase (Pyk2) show a high expression in glioma cell lines and have an influence on increased cell proliferation and migration of glioma cells in vitro and in vivo. The aim of this study was to correlate the coexpression of FAK and Pyk2 to the WHO grade of malignancy in human astrocytomas. Immunohistochemical staining scores of FAK and Pyk2 were analyzed in 331 astrocytomas and correlated to each other and to the WHO grade. Significant coexpression of FAK and Pyk2 in astrocytomas was demonstrated. Pyk2 expression occurred much more frequently and with higher expression scores within the different WHO grades. Beyond this, a significant correlation between the WHO grade of malignancy of astrocytomas and the expression of FAK, as well as of Pyk2, was detected. This connection and the roles of these two tyrosine kinases in the progression of tumors should be confirmed by further studies.     

Expression pattern of the water channel aquaporin-4 in human gliomas is associated with blood-brain barrier disturbance but not with patient survival

Aquaporin-4 (AQP4), the most prominent CNS water channel, is restricted to the glia limitans and astrocytic endfeet. We previously showed the loss of spatial AQP4 expression in glioblastomas and a redistribution across the cell surface. However, opposing AQP4 functions have been described: protective in vasogenic but detrimental in cytotoxic brain edema. Thus, specific AQP4 induction to prevent or reduce vasogenic edema is suggested. To elucidate the AQP4 role in brain tumors, we investigated 189 WHO grade I-IV gliomas by immunohistochemistry and the prognostic significance for patients' survival. In gliomas, a remarkable de novo AQP4 redistribution was observed in comparison with normal CNS tissue. Surprisingly, the highest membraneous staining levels were seen in pilocytic astrocytomas WHO grade I and grade IV glioblastomas, both significantly higher than in WHO grade II astrocytomas. AQP4 up-regulation was associated with brain edema formation; however, no association between survival and WHO grade-dependent AQP4 expression was seen. Hence, AQP4 redistribution may go along with other tumor properties, such as vascular proliferation and resulting blood-brain barrier disturbance, features usually prominent in pilocytic astrocytomas WHO I and glioblastomas WHO grade IV. In summary, our findings question the protective role of AQP4 in vasogenic brain edema. Although AQP4 was associated with brain edema formation, one has to question the suitability of AQP4 induction as a promising approach in vasogenic brain edema prevention and treatment. In addition, our results provide unexpectedly high AQP4 levels in pilocytic astrocytomas and present AQP4 as tumor progression marker in WHO grade II-IV astrocytomas.     

An immunohistochemical study of aldolase C in normal and neoplastic nervous tissues

Summary Cellular localization of aldolase C isozyme was examined in the normal human brain and in nervous tissue tumors by the indirect immunoperoxidase method using an antibody to aldolase C. In normal brain tissues, staining was most prominent in astrocytes and Purkinje cells, although faint staining was also occasionally observed in some other neurons. Oligodendroglia and ependymal cells showed no distinct staining. The nervous tissue tumors we examined included 34 gliomas (ten astrocytomas and 24 anaplastic gliomas), 30 medulloblastomas, and seven neuronal tumors. Positive staining was observed in some gliomas, but not in the medulloblastomas and neuronal tumors examined. In gliomas, nine of ten astrocytomas and six of 24 anaplastic gliomas showed positive staining in their main constituent cells. In the remaining gliomas, most constituent cells were unstained or positive cells were only sporadically present. These findings indicated that aldolase C was expressed in some of astrocytic glioma cells as in the normal counterpart, more frequently in more differentiated form.     

胶质瘤中EGFR扩增、过表达及其与肿瘤增殖关系的研究

目的探讨表皮生长因子受体（EGFR）在胶质瘤中扩增、过表达及其在肿瘤增殖中的作用机制。方法应用SP免疫组化法、RT—PCR、Southern印迹法检测6例正常脑组织、50例不同级别胶质瘤及2个体外胶质瘤细胞系中在EGFR蛋白水平、mRNA水平、DNA水平的表达及扩增情况，以及与肿瘤增殖活性的相关性。结果不同级别的胶质瘤中，表达与扩增程度不同，Ⅱ级与Ⅲ、Ⅳ级肿瘤之间比较具有显著性差异：EGFR过表达与Ki-67在胶质瘤中的表达呈正相关．而EGFR过表达与扩增并不一致。结论EGFR过表达与胶质瘤的增殖活性增高有密切相关性，推测EGFR过表达是肿瘤进展中的早期事件而非进展期事件。     

人脑胶质瘤中Fas及FasL的表达

目的　探讨Fas及FasL基因在人脑胶质瘤中的表达 ,与肿瘤的病理类型及恶性程度的关系。方法　应用Fas及FasL多抗和Ki 6 7单抗免疫组化染色检测 6例正常脑组织及 6 4例人脑胶质瘤。结果　Fas和FasL在胶质瘤中的总表达率分别为 83%和 75 % ,并随WHO分级升高而升高 ,与Ki 6 7LI呈正相关。Fas、FasL共同阳性率 (共表达率 )为 71% ,与肿瘤级别呈正相关。结论　脑胶质瘤中Fas及FasL表达与肿瘤病理类型及恶性程度密切相关     

Analysis of activated lymphocytes and antigen-present macrophage in human brain tumors using double immunofluorescence staining

Twenty-eight human brain tumors (18 gliomas and 10 metastatic brain tumors) were examined immunohistochemically using anti-Leu 1, -Leu 2 a, -Leu 3a + 3b, -LeuM 5, -HLA-DR, IL-2 receptor, -HLA-ABC and Ki-67 monoclonal antibodies (MoAb). Also, in the specimens, in which Leu 1+ cells and Leu M5+ cells infiltrate, simultaneous detection of Leu 2a, Leu 3a + 3b, or Leu M5 and HLA-DR, was performed by double immunofluorescence staining to analyze the T cell activation and antigen-present macrophage (M phi). Most of low-grade gliomas with low percentage of Ki-67+ cells showed only little lymphocyte and M phi's infiltration. THEre was a tendency toward a marked degree of T cell and M phi infiltration in malignant glioma with higher percentage of Ki-67+ cells. However, in metastatic brain tumors, M phi did not tend to infiltrate. IL-2 receptor+ cells was absent in the majority of brain tumors. Tumor cells and vascular endothelial cells also expressed HLA-DR antigens. The majority of tumor cells expressed HLA-A, B, C antigens. There were no correlation among the degree of T cell and M phi infiltration, MHC antigen expression, and percentage of Ki-67+ cells. Double immunofluorescence staining demonstrated that 42.4% of Leu 2a+ cells, 34.7% of Leu3a+ + 3b+ cells and 32.7% of M5+ cells are HLA-DR positive in glioma, and that 50.2% of Leu2a+ cells, 59.4% of Leu3a + 3b+ cells and 67.3% of LeuM5+ cells are HLA-DR positive in metastatic brain tumors.(ABSTRACT TRUNCATED AT 250 WORDS)     

人脑胶质瘤中Survivin、Ki-67的表达及其临床意义

目的探讨Survivin和Ki-67抗原在人脑胶质瘤中的表达及其临床意义。方法应用免疫组化SP法检测10倒正常脑组织和68例人脑胶质瘤中Survivin和Ki-67的表达。结果Survivin和Ki-67在正常脑组织中均不表达,而在各级别的人脑胶质瘤中均有表达,差异极显著（P％0.01）,Survivin和Ki-67的表达在高级别胶质瘤中显著高于低级别胶质瘤（P％0．01）,且Survivin和Ki-67的表达呈显著正相关（P〈0．05）。结论Ki-67可以作为评估胶质瘤细胞增殖的良好指标,Survivin和Ki-67的表达可以判断胶质瘤的恶性程度,为临床病理分级提供有意义的依据。     

人脑胶质瘤免疫抑制因子TGFβ2及TGFβ1的基因表达

目的 研究人脑胶质瘤主要免疫抑制因子转化生长因子TGFβ2及TGFβ1的基因表达与其胶质瘤恶性程度的关系。方法 采用Northern杂交,免疫组化和Western杂交法检测了50例胶质瘤,。3例恶笥胶质瘤体外细胞系和8例正常脑细胞TGFβ2的达表水平,同时检测其同型异构体TGFβ1的表达水平,结果 正常脑组织几无TGFβ2和TGFβ1表达,而胶质瘤均表达2．8和或5．1kb的TGFβ2mRNA片段和约25000u及30000u的蛋白,TGF和TGFβ1表达水平随肿瘤恶性程度增高而增高,结论 TGFβ2和TGFβ1表达水平与肿瘤恶性程度呈正相关,TGFβ2和TGFβ1可作为恶性胶质瘤免疫基因治疗的侯选基因。     

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

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

Expression of tenascin in human gliomas: its relation to histological malignancy,tumor dedifferentiation and angiogenesis

Summary The immunohistochemical distribution of tenascin (TN), fibronectin (FN), and laminin (LN) was investigated in 56 human gliomas (8 astrocytomas, 15 anaplastic astrocytomas, and 33 glioblastomas) with regards to the histological degree of malignancy and the degree of tumor cell differentiation evaluated by the staining of glial fibrillary acidic protein (GFAP). In 8 anaplastic astrocytomas and 28 glioblastomas, TN was predominantly immunolocalized in the basement membrane zone of the proliferating tumor vessels; sections of all astrocytomas were negative for TN staining. FN was localized in the basement membrane zone of the vessels in all astrocytomas, 12 anaplastic astrocytomas, and 22 glioblastomas. In 7 anaplastic astrocytomas and 19 glioblastomas, both TN and FN were expressed to various degrees in the tumor vessels. However, most of the TN-positive vessels did not express FN, and most of the FN-positive vessels were negative for TN staining. Furthermore, in 6 anaplastic astrocytomas and 12 glioblastomas, either TN of FN, but not both, were expressed in any area on serial sections. Most of the tumor cells around TN-positive, FN-negative tumor vessels did not express GFAP. On the other hand, GFAP was present in most tumor cells around TN-negative, FN-positive vessels. LN was detected in all vascular and pial-glial basement membrane zone of the tissues examined. These findings indicate that the degree of histological malignancy and the degree of cell dedifferentiation of human gliomas correlate well with the expression of TN, but are inversely correlated with the expression of FN. We postulate that the expression of TN, but not of FN, plays a role in the promotion of angiogenesis in malignant gliomas.     

Expression and functional activity of osteoprotegerin in human malignant gliomas

Apo2L/TRAIL-based therapy is a promising experimental approach to the treatment of human malignant gliomas. Osteoprotegerin (OPG) is a soluble decoy receptor for Apo2L/TRAIL that antagonizes Apo2L/TRAIL-induced apoptosis. High levels of OPG expressed by tumor cells might therefore abrogate the activity of exogenously added or adenovirally expessed Apo2L/TRAIL. Here we assessed the expression of OPG in human gliomas in vivo, in primary glioma cell cultures and in established glioma cell lines. Immunohistochemistry revealed weak OPG immunoreactivity in up to 5% of the tumor cells in 8 of 13 glioblastomas. Strong OPG labeling was detected in single scattered tumor cells in one of these specimens. Five glioblastomas did not express OPG. High OPG expression was found in 1 of 6 primary glioma cell cultures and in 1 of 12 established glioma cell lines, T98G. OPG released by T98G cells was biologically active in that it inhibited Apo2L/TRAIL-induced apoptosis in sensitive glioma cells. Altogether, however, these data suggest that OPG expression may not be a major pathway of glioma cell resistance to future Apo2L/TRAIL-based therapeutic approaches.     

血管内皮生长因子与水孔蛋白4在胶质瘤及脑转移瘤中的表达及意义

目的 探讨血管内皮生长因子(VEGF)与水孔蛋白4(AQP4)在胶质瘤及脑转移瘤中的表达,并探讨两者与胶质瘤及脑转移瘤的组织病理学关系及在瘤周水肿形成过程中的作用.方法 选择福建医科大学附属第一医院神经外科自1999年至2001年手术切除并经病理检查证实的胶质瘤石蜡组织标本73例和脑转移瘤组织标本15例,并另取正常脑组织标本8例作为对照,应用免疫组织化学方法检测组织标本中VEGF与AOP4的表达.结果 正常脑组织中未见VEGF表达:高级别胶质瘤与低级别胶质瘤之间、低级别胶质瘤与正常脑组织之间、脑转移瘤与正常脑组织及低级别胶质瘤之间VEGF阳性表达比较差异有统计学意义(P<0.05),而脑转移瘤与高级别胶质瘤之间VEGF阳性表达比较差异无统计学意义(P>0.05).AQP4在所有组织标本中均有表达,正常脑组织与高级别胶质瘤、脑转移瘤之间,低级别胶质瘤与高级别胶质瘤、脑转移瘤之间AQP4阳性表达比较差异有统计学意义(P<0.05),而正常脑组织与低级别胶质瘤之间、脑转移瘤与高级别胶质瘤之间AQP4阳性表达比较差异无统计学意义(P>0.05).Spearman相关分析显示两者在胶质瘤及脑转移瘤组织中表达呈正相关关系(r=0.516,P<0.05).结论 VEGF与AQP4是参与形成肿瘤周围水肿的重要分子生物学因素,且两者可能存在某种协同作用.     

Altered expression of Cx43 in astrocytic tumors

OBJECTIVE: To evaluate the Cx43 expression of astrocytic tumors and correlate their expression with degrees of malignancy and proliferation activity of tumors. METHODS: Cx43 expression in eight normal brain tissues, 44 freshly resected astrocytic tumor specimens and four malignant glioma cell lines were examined by Northern blot analysis and immunohistochemical staining. The proliferation activity of tumors was measured by Ki67 labeling index (Ki67LI) with immunostaining. Scrape loading and dye transfer assay was used for examination of gap junction intercellular communication (GJIC) in glioma cell lines. RESULTS: Twenty-three out of 44 astrocytic tumors (52%) expressed both Cx43 mRNA and Protein. Cx43 expression was decreased with the ascending of tumor grade and negatively correlated with Ki67LI. GJIC was interrupted in glioma cell lines deficient in Cx43 expression. CONCLUSIONS: Cx43 expression level is inversely correlated with the tumor grade and proliferation activity of tumor, suggesting the potential role of Cx43 in the malignant progression of astrocytic tumors.