Abstract:       Background and purpose: The incidence of esophageal cancer of Kazakh race is higher than that of Han people. EphA2, as a member of Eph protein family, is related to a variety of malignant tumors. This study used immunohistochemical method and enzyme-linked immunoassay to detect EphA2 in tissues and serums of Kazakh and Han patients. Therefore to analyze the expression differences of EphA2 in esophageal squamous cell carcinoma (ESCC) tissues and serum of Kazakh and Han patients in Xinjiang, and the relationship with pathological features. Methods: The expression of EphA2 protein was detected by immunohistochemistry method in 100 cases of ESCC tissues and adjacent normal esophageal tissues; Then was tested by ELISA in those cases’ serum and 60 healthy persons. Results: The positive expression rate of EphA2 protein in ESCC and corresponding adjacent tissues were 72.0%, 28.0% in Kazakh, and 62.0%, 26.0% in Han people, respectively, and the differences were statistically significant (P=0.000) in the 2 nations. EphA2 protein levels in serum of ESCC and healthy persons, and Kazakh were (58.36±12.60) and (29.39±7.34) pg/mL, Han Chinese were (58.79±13.29) and (29.39±7.34) pg/mL respectively, there were statistical significance (P=0.000). In ESCC of Kazakh and Han people, EphA2 protein expression had relationship with lymph node metastasis, TNM stage and tumor depth of invasion (P<0.05). In the serum of Kazakh and Han ESCC patients, the expression of EphA2 protein was related to TNM stage (P<0.05), while in the Kazakh esophageal cancer, the expression level was also correlated with the depth of tumor invasion (P=0.001). The positive expression rates of EphA2 protein in Kazakh and Han ESCC specimens were 72.0% and 62.0%, respectively; the protein level in the serum of patients in the 2 nations were (58.36±12.60) and (58.79±13.29) pg/mL, respectively. The protein levels in tissues and serum of the 2 different nations has no statistical significance (P>0.05). Conclusion: The high expression of EphA2 protein may contribute to the occurrence, invasion and metastasis of Kazakh and Han ESCC patients. EphA2 protein expression in tissues and serum of patients with ESCC may be related to the primary tumor invasion, lymph node metastasis and TNM stage. The expression of EphA2 protein in peripheral blood of patients with esophageal cancer in Kazakh may be related to depth the of invasion.

Key words: Esophageal neoplasm, Squamous cell carcinoma, EphA2, Immunohistochemical method, ELISA