| Background:Glioma is the most common type of malignant brain tumor, Although actively treatments consisting of surgical resection, adjuvant radiation therapy and chemotherapy, prognosis for advanced patients suffering from high-grade gliomas remains poor, especially glioblastoma multiform(GBM). Glioma especially high-grade glioma has high aggressive, and neoplasm tissues often hit the around normal brain tissue, and relapse easily after operation, patients has very short survival time. For GBM patients, the average median survival is only about one year, during the past decade has changed little. Therefore, an urgently new treatment strategies and the development of new treatments is under the way.In recent years, with the development of tumor molecular biology, molecular target therapy has become an important treatment and has made significant progress, especially the epidermal growth factor receptor (EGFR) target therapy, which has become a hot research area. Epidermal growth factor receptor (EGFR; erb-B1) is a170-kd transmembrane glycoprotein receptor and a member of the c-erbB family of tyrosine kinase receptor proteins. EGFR is activated by binding to its ligands such as EGF and transforming growth factor-alpha (TGF-a), resulting in homo-or hetero-dimerization with another member of the c-erbB family and subsequent autophosphorylation and initiating the downstream signalling pathways. In recent research, about40-50%gliomas have abnormal EGFR expression, and accompanied by amplification and mutation, the most common mutation is epidermal growth factor receptor variant Ⅲ (EGFRvⅢ). EGFRvⅢ was not present in normal tissue and indentified as specific mutation, so it may provide specific targets for immunotherapy and new way for target therapy.The aim of our study was to evaluate the expression levels of EGFR and EGFRvⅢ in human primary gliomas tissues by immunohistochemistry (IHC) and EGFR gene amplification by Fluorescence in situ hybridization (FISH). We investigated the association between EGFR protein overexpression and gene amplification in gliomas. In addition, whether EGFR overexpression and/or gene amplification were associated with a variety of clinicopathological features including survival and prognosis was determined.Objective:To investigate the protein overexpression and gene status of EGFR and its mutant variant Ⅲ (EGFRvⅢ) in gliomas, assess the association with clinicopathological parameters to survival, and study the EGFR status and survival in different age distribution of glioma patients, which may help to identify their potential role as molecular targets of therapy.Methods:Immunohistochemistry (IHC) was performed to analyze the expression of EGFR and EGFRvⅢ, and Fluorescence in situ hybridization (FISH) was performed to analyze the EGFR amplification in158cases with primary gliomas (grade Ⅰ14cases, gradeⅡ32cases, grade Ⅲ27cases, grade Ⅳ85cases) and20cases normal brain tissue. Statistical analysis was done using SPSS, version16.0. Univariate and multivariate Cox regression analyses were performed to identify the clinical and molecular variables related to survival. Kaplan-Meier survival curves were also calculated. The associations between protein expression and different clinical parameters were evaluated using Fisher’s exact test or χ2test. The differences between groups were tested by log-rank analyzes. The cutoff probability value for all tests was set at <0.05for statistical significance.Results:The overexpression of EGFR in20cases normal brain tissue,14cases grade Ⅰ,32cases grade Ⅱ,27cases gradeⅢ,85cases grade Ⅳ were0%(20/20),7.1%(1/14)50.0%(16/32),62.9%(17/27), and80.0%(68/85), respectively. The overexpression of EGFR has statistical significance in different grade gliomas (P<0.05). In102cases (64.6%) of EGFR overexpression,55cases (53.9%) were scored as3+EGFR staining and47cases (46.1%) scored2+staining. The overexpression of EGFR was significantly correlated with WHO grade and KPS (both P<0.05), but not with other parameters (P>0.05). The overexpression of EGFR has no statistical significance among age>60and <60years glioma patients (P>0.05).The expression of EGFRvⅢ in20cases normal brain tissue,14cases grade Ⅰ,32cases gradeⅡ,27cases gradeⅢ,85cases grade Ⅳ were0%(0/20),0%(0/14),9.4%(3/32),22.2%(6/27) and45.2%(38/84), respectively. The expression of EGFRvⅢ has statistical significance in different grade gliomas (P<0.05). The expression of EGFRvⅢ was significantly correlated with WHO grade, gender, age and KPS (all P<0.05), but not with other parameters. The expression of EGFRvⅢ was more common in age≥60than<60glioma patients (P<0.05).EGFR gene amplification in20cases normal brain tissue,14cases grade Ⅰ,32cases grade Ⅱ,27cases gradeⅢ,85cases grade Ⅳ were0%(0/20),0%(0/14),3.1%(1/32),22.2%(6/27)and45.9%(39/85), respectively. EGFR gene amplification was found in46cases (29.1%), EGFR amplification positive cases were present in44cases (95.7%) of EGFR overexpression cases, of which were consisted of27cases (61.4%) scored3+for IHC and17cases (38.6%) scored2+for IHC. EGFR amplification percentage was higher in high-grade than low-grade gliomas (P<0.05). EGFR gene status was significantly associated with WHO grades, age and KPS scores (all P<0.05) of patients with gliomas, but not with other parameters. EGFR amplification in patients older than60years of age was significantly higher than that in younger patients (P<0.05). EGFR amplification was significantly correlated with overexpression of EGFR (P<0.05) and expression of EGFRvⅢ (P<0.05).The median survival in different grade was96.3,84.9,14.6and12.3months respectively (P<0.05), and the median survival in high-grade and low-grade gliomas was86.4and12.5months respectively (P<0.05). Univariate analyses of each factor with Cox log-rank analysis show that WHO grade, age, EGFR overexpression, EGFRvⅢ expression, EGFR gene amplification, radiotherapy, resection range, KPS and tumor size were significantly associated with prognosis (all P<0.05). In addition, we performed a multiparametric Cox regression analysis, including the following variables:WHO grade, patient gender, age, KPS, expression of EGFR and EGFRvIII, EGFR amplification, radiotherapy, resection range, chemotherapy, tumor size and tumor location. Cox’s multifactor analysis showed WHO grade (P<0.05), age (P<0.05), KPS (P<0.05) and EGFR gene amplification (P<0.05) were independent prognosis factors for human gliomas. The median survival of patients with EGFR amplification was significantly shorter than no EGFR amplification (45.8and11.9months, respectively, P<0.05). In patients above60years old, we found WHO grade (P<0.05), KPS (P<0.05) and EGFRvⅢ (P<0.05) were independent prognosis factors.Conclusions:1, EGFR expression and gene abnormality are involved in the development of gliomas, and EGFR variant Ⅲ is related to biological behaviour of gliomas2, EGFR amplification and EGFR protein expression has a significant and positive correlation 3, EGFR amplification was an independent prognosis factor in all age gliomas patients, and EGFRvⅢ was an independent prognosis factor in=60years gliomas patients4, EGFR and its variant Ⅲ may be clinically useful prognostic markers and provide new strategies for EGFR-targeted therapy... |
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