EGFR Overexpression And Gene Amplification And Their Clinicopathology Correlation In Esophageal Squamous Cell Carcinoma

Background:Esophageal carcinoma is one of the most frequent malignancies in China, and squamous cell carcinoma (SCC) is the main histological type. It generally has a poor prognosis because it is usually in an advanced stage at the time of diagnosis. Despite recent progress in chemotherapeutic, radiotherapeutic and surgical treatment, the five-year survival rate is still less than 20%. 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. EGFR is widely distributed in human epithelial cell membrane, and the majority of epithelial tumors have high expression of EGFR. Signal transduction effect mediated by EGFR includes tumor cell proliferation, migration, apoptosis inhibition, and angiogenesis and so on. Therefore, EGFR is one of the most promising molecular targets, but the eligibility criteria for EGFR target therapy in esophageal carcinomas are not fully established. There is little research to evaluate ESCC EGFR overexpression and gene status in China. But it is of importance for selecting patients who may respond to EGFR target therapy. In addition, Akt and Raf are located in the important position in the PI3K/Akt and Ras/Raf/MEK/ERK pathway respectively, which mediated by EGFR. More and more information demonstrate:AKT kinase and its mediated PI3K/Akt pathway, and the Raf kinase and its mediated Ras/Raf/MEK/ERK pathway play an important role in tumor occurrence and development. In addition, there are evidences that most of the tumors are not dominated by a single signal transduction pathway, so multi-target therapy may achieve greater efficacy. However, there is little research for their co-expression in esophageal carcinoma at home and abroad. Whether Akt or B-raf expression is well correlated with EGFR expression and whether they can prompt the prognosis of patients is currently uncertain. In order to help to identify those patients who may benefit from anti-EGFR therapy and/or multi-target therapy, we sought to clarify:(1) the ESCC EGFR expression and gene status; (2) the ESCC Akt and B-raf expression; (3) the correlation between EGFR expression and gene status; (4) the correlation of EGFR, Akt, and B-raf in ESCC; (5) the correlation between the above parameters and clinicalpathological parameters; (6) survival analysis.Objectives:To investigate the protein overexpression and gene status of EGFR and expression of EGFR downstream signal molecular Akt, B-raf in ESCC, and help to identify patients who may benefit from EGFR target therapy and mutil-target therapy.Methods:IHC was performed to analyze the expression of EGFR in 50 cases of normal esophageal tissue,50 cases of squamous epithelial reactive hyperplasis,50 cases of low grade intraepithelial neoplasia,42 cases of high grade intraepithelial neoplasia, and 105 cases of ESCC. FISH was performed to analyze the gene status of EGFR in 84 cases of ESCC,18 cases of squamous epithelial dysplasia, and 18 cases of normal esophageal tissue. In addition, IHC was performed to analyze the expression of Akt, B-raf in 11 cases of normal esophageal tissue,16 cases of squamous epithelial dysplasia and 105 cases of ESCC.Statistical analysis was performed using SPSS 15.0. x2 test and Kaplan-Meier survival analysis was performed, and P< 0.05 was considered statistically significant. Results:The IHC-positive rates of EGFR in 50 cases of normal esophageal tissue,50 cases of squamous epithelial reactive hyperplasis,50 cases of low grade intraepithelial neoplasia,42 cases of high grade intraepithelial neoplasia, and 105 cases of ESCC were 0(0/50),2%(1/50),4%(2/50),76%(32/42), and 86%(90/105) respectively. The difference of expression of EGFR among different esophageal groups had statistically significance (p<0.05). Among the 105 cases of ESCC, overexpression of EGFR was found in 90 cases (86%), of which 55 cases scored 3+for EGFR staining and 35 cases scored 2+staining. In ESCC, the expression of EGFR was significantly correlated with depth of invision and TNM stage (p<0.05), but not with other parameters. The FISH-positive rates of EGFR in 84 cases of ESCC,18 cases of squamous epithelial dysplasia, and 18 cases of normal esophageal tissue were 33.3%(28/84),0(0/18) and 0(0/18) respectively. In ESCC, EGFR gene amplification was found in 20(24%) cases, high polysomy in 8(9.5%) cases, disomy in 35 cases, low trisomy in 17 cases, high trisomy in 4 cases; EGFR FISH-positive was significantly correlated with depth of invasivion, lymph node metastasis and TNM staging(p<0.05). EGFR FISH-positive was significantly associated with overexpression of EGFR. The IHC-positive rates of Akt in 11 cases of normal esophageal tissue,16 cases of squamous epithelial dysplasia, and 105 cases of ESCC were 82%(9/11),88%(14/16), and 67%(70/105); B-raf 27%(3/11),44%(7/16), and 73%(77/105). The difference of expression of B-raf among different esophageal groups had statistically significance(p < 0.05), while that of the expression of Akt had no statistically significance. In ESCC, the expression of Akt was significantly correlated with age, differentiation and depth of invision(p< 0.05), the expression of B-raf was significantly correlated with lymph node metastasis and TNM stage(p< 0.05). The relationship of EGFR expression to B-raf in ESCC was significant(p< 0.05). Conclusions:EGFR overexpression and gene abnormality are involved in the tumorigenesis and development of esophageal squamous cell carcinomas. Expression of EGFR and its downstream molecules Akt and B-raf are related to biological behaviors of esophageal squamous cell carcinomas. Our data provided an important basis for anti-EGFR target therapy of esophageal squamous cell carcinomas.