ObjectiveTo investigate the expression level and the clinical significance of Traf-2 and Nck-interacting protein kinase (TNIK) in gastric cancer tissues.MethodsWe retrospectively collected 78 cases of gastric cancer and its adjacent tissues which were diagnosed by surgery and pathology, all the patients received surgery in the Department of General Surgery in Luoyang Central Hospital Affiliated to Zhengzhou University, from July 2014 to December 2017, as well as 42 cases of gastric ulcer tissues in the same period. The expression of TNIK protein was detected by using immunohistochemical method and Western blot method in 78 cases of human gastric cancer tissues, corresponding adjacent normal tissues, and 42 cases of gastric ulcer tissues, the relationship between expression of TNIK protein and clinicopathologial features of gastric cancer was explored.ResultsThe positive expression rate of TNIK protein in gastric cancer tissues was 66.67% (52/78), and adjacent cancer tissues showed low expression rate of 11.54% (9/78), while it was 21.43% (9/42) in gastric ulcer tissues. On the positive expression rate of TNIK protein, gastric cancer tissues compared with adjacent cancer tissues and gastric ulcer tissues, the difference was statistically significant (P<0.05), however, there was no statistically significant difference between adjacent cancer tissues and gastric ulcer tissues (P>0.05). Western blot method showed that the expression level of TNIK protein in gastric cancer tissues was all significantly higher than that in adjacent cancer tissues and gastric ulcer tissues, the differences were statistically significant (P<0.05), but the difference was not significant when compared the adjacent cancer tissues and gastric ulcer tissues (P=0.772). The expression of TNIK protein was irrelevent to sexual distinction, CEA value, tumor diameter, and pathological type (P>0.05), while it was closely related to patients’ age, TNM stage, differentiation grade, distant metastasis, and lymph node metastasis (P<0.05). The prognosis of patients with positive expression of TNIK protein was worse than that of patients with negative expression of TNIK protein (P<0.05).ConclusionTNIK protein is highly expressed in gastric cancer tissues, which is associated with poorly prognostic factors and poor prognosis, and it may be a therapeutic target in patients with gastric cancer.