Expression Of EGFR And β-catenin In Esophageal Squamous Cell Carcinoma And Its Clinical Significance

Backgrand and Objective: Esophageal carcinoma is one of the gastrointestinal malignancies which threatens severely the health of the human beings, and esophageal squamous cell carcinoma(ESCC) is more common. There is higher incidence rate in china than other countries over the world, what' more, its death rate is very high in china. In our country, it is the second next to gastric cancer in gastrointestinal carcinoma. It is particularly prevalent in northern china, especially Linzhou city of Henan province that is one of high-incidence areas in china, even over the world. Carcinogenesis of esophageal carcinoma is involved in multiple factor and steps. Poor prognosis is mainly because of strong reproductive activity and invasiveness, enen if some superficial esophageal carcinoma of slow growth is also accompanied with deep infiltration. With the development of molecular biology, it has become the development direction to raise therapetic efficacy of malignant tumor that we make use of the indexes of molecular biology to judge prognosis, guide combined therapy and develop molecular biotherapy. Epidermal growth factor receptor(EGFR) belongs to I type transmembrane protein tyrosine kinase which bindings its ligand activates a series of cascade reaction of the signal transduction system of downstream, and finally causes increase of transcriptional level of intranuclear response genes which stimulate cell proliferation and transformation. Nearly, Some studies have shown that EGFR plays a impont role in proliferation, differentiation, anti-apoptosis, neovascularization and metastasis of tumour cell.β-catenin is a kind of multifunction protein which not only participate the formation of E-cad/cat complex that produce an effect in cell adhesion, but also is a key link of Wnt signal transduction pathway that participate the regulation of cell proliferation and differentiation. Study shows that the activation of EGFR can regulate the phosphorylation ofβ-catenin in E-cad/cat complex, which results in the dissociation ofβ-catenin from the complex, accordingly that can facilitate the tumorous metastasis. In order to provide some evidence in elucidating the prognosis and guiding treatment, the experiment investigates the expression of EGFR andβ-catenin in esophageal squamous cell carcinoma and analyzes their interrelationship with clinicopathological parameters.Materials and methods: (1) S-P Immunohistochemistry was used. 60 cases of esophageal squamous cell carcinoma tissue were obtained from resected samples in Surgery at the Second hospital of Jiaozuo City from January 1992 to August 2000 (the same case included esophageal squamous cell carcinoma and tumor-adjacent normal esophageal tissue beyond 5 meters), which were confirmed by pathology (H&E stained slides). The patients who included male 33 and female 27 were all from 35 to 73 yearold with a mean age of 50. Well, moderately, poorly differentiated samples were 34, 12, 14, respectedly. 31 cases had lymph node metastasis, and 29 cases had no lymph node metastasis. According to the standard of TNM staging, the patients with stage I, II, III, IV were 17, 12, 15, 16, respectively. As for infiltrative depth, the patients with T₁, T₂, T₃, T₄ were 13, 12, 21, 14, respectively. Follow-up period ranged from 6 to 18 months after surgery. Among these cases, 29 cases died, 31 cases still survive.(2) Mouse anti-human monoclonal antibodies (anti-EGFR, anti-β-catenin), immunohistochemical and DAB kit were purchased from Zhongshan Jinqiao Biotechnology Limited Company, Beingjing. Paraffin sections of 4μm thickness were employed to restore antigen after deparaffinage, hydration and heating by use of electric stove. EGFR,β-catenin monoclonal antibodies diluted 1:100. PBS served as negative control, and confirmed ESCC tissues of EGFR,β-catenin positive staining served as positive control.(3) SPSS10.0 statistical software was used to analyze the data. The x² test and Spearman rank correlation coefficient analysis were used to assess the univariate association between the immunohistochemical status and the clinicopathological characteristics. Survival analysis methods included Kaplan-Meier, Log-rank test. A difference was considered significant if P value was less than 0.05.Results: 1. The positive location and expression of EGFR,β-catenin: (1) The positive expression of EGFR was mainly located in cytoplasm, but nearby matrix was not observed positive staining. The positive expression rates of tumor-adjacent normal esophageal tissues and ESCC tissues werel8.3%(11/60), 71.7%(43/60) respectively. The difference was significant (x²=34.478, P<0.01) .(2) The positive staining ofβ-catenin in tumor-adjacent normal esophageal tissues was all located on cell membrance, and there was no visible positive signal in cytoplasm. Abnormal expression was observed in ESCC tissues, which meant the membrance staining decreased and mainly located in the cytoplasm or nucleus. The positive expression rates of tumor-adjacent normal esophageal tissues and ESCC tissues were 91.7%(55/60), 65%(39/60) respectively. The difference was significant (X²=34.478, P<0.01) .2. The relationship between the expression of EGFR,β-catenin and clinocopathologic characteristics, prognosis: (1) In ESCC, the positive expression rate of EGFR increased with higher dedifferentiation, deeper infiltration and lymph node metastasis. The positive rates were 57.7%(15/26), 82.4%(28/34) respectively in carcinomas with well or moderately, poorly differentiation. The positive rates were 48.0%(12/25) in subadventitial infiltration group (T1, T2)versus 77.1%(27/35)in adventitial or extraadventitial group(T3, T4). In cancer tissues with no lymph node metastasis or lymph node metastasis, The positive rates were 58.6%(17/29), 83.9%(26/31) respectively. All the differences were signifinat(P<0.05). According to the standard of TNM staging, the patients of positive expression of EGFR with stage III, IV were 28 cases(90.3%), which was significantly higher than the ones with stage I, II(51.7%, 15/29)(P<0.05). About eighteen-month survival rate, the survival rate of the patients who had positive expression of EGFR was 41.9%(18/43) in comparison with the one of the patients who had negtive expression of EGFR, 76.5%(13/17). There was significant difference between them(P<0.05).(2) In 60 cases of ESCC, the positive expression rate ofβ-catenin in carcinoma tissues with well differentiation(88.5%, 23/26) was significantly higher than the ones with moderately, poorly differentiation(47.8%,16/34)(P<0.05). Significant difference was found between the positive expression rate in cancer tissues with lymph node metastasis(82.8%, 24/29) and the one with no lymph node metastasis (48.4%, 15/31)(P<0.05). The positive expression rate ofβ-catenin in carcinoma tissues with stage I , II was 79.3%(23/29), stage III, IV 51.6%(16/31). There was significant difference between them(P<0.05). The eighteen-month survival rate of the patients who had positive expression ofβ-catenin, 59.0%(23/39) was significantly higher than the one of the patients who had negtive expression ofβ-catenin, 38.1%(8/21). No significant difference was seen in infiltrative depth. The positive expression rate ofβ-catenin in carcinoma with T1, T2 was 56%( 14/25) versus 71.4%(25/35) in carcinoma with T3, T4.3. The correlative analysis to the expression of EGFR andβ-catenin in ESCC: The expression of EGFR andβ-catenin were both positive in 23 cases of ESCC but both negative in 1 cases. 20 cases were EGFR positive andβ-catenin negative. 16 cases were EGFR negative andβ-catenin positive. There was negative correlation between them(r= -0.384, P=0.002).Conclusions: 1. The overexpression of EGFR was seen in ESCC. There was relationship between the expression of EGFR and TNM staging, differentiated grade, lymph node metastasis, eighteen-month survival rate and infiltrative depth. The overexpression of EGFR may play a important role in the development, infiltration and metastasis of Esophageal squamous cell carcinoma, and the patients who have the overexpression of EGFR have poor prognosis.2. In ESCC, the membranous expression ofβ-catenin decreased, and the abnormal expression was seen in cytoplasm or nucleus. The expression ofβ-catenin had correlation with TNM staging, differentiated grade, lymph node metastasis, eighteen-month survival rate, but no correlation with infiltrative depth. The results indicate that the abnormal expression ofβ-catenin may participate in the development and metastasis of Esophageal squamous cell carcinoma, which has relationship with poor prognosis.3. In ESCC, there was negative correlation between the expression of EGFR andβ-catenin. This indicates certain controlling relation may exist in them. They cooperate to take part in the development and evolution.4. EGFR andβ-catenin had close relationship in developing and metastasizing of ESCC. Combined mornitoring the two indexex may supply help in judgement of the developing degree and prognosis of Esophageal carcinoma, and supply a new method for gene therapy of Esophageal carcinoma.