ObjectiveTo determine the expressions of Lgr5 protein and Ki-67 protein in gastric cancer tissues, and to analyze the possible function in the carcinogenesis and development of gastric cancer.MethodsThe SABC immunohistochemical method was adopted to examine the expressions of Lgr5 protein and Ki-67 protein in the 69 paraffin slices of gastric cancer from the patients, with the adjacent normal gastric tissue as the control group. The statistical relationship between the expressions of these two kinds of proteins and clinicopathologic features of gastric cancer was examined respectively.ResultsIn the gastric cancer tissue group, the expressions of Lgr5 protein and Ki-67 protein upregulated in comparison to the adjacent normal gastric tissue group [Lgr5 protein: 87.0% (60/69) versus 16.7% (5/30), χ2=45.81, P<0.001; Ki-67 protein: 79.7% (55/69) versus 36.7% (11/30), χ2=17.43, P<0.001]. The expressions of Lgr5 protein and Ki-67 protein all upregulated in the N1–N3 stage groups, lowly differentiated+undifferentiated groups and positive Helicobacter pylori (HP) groups. The expression of Lgr5 protein upregulated in the T3+T4 stage groups in comparison to T1+T2 stage groups, while, no significant relationship was found in the expression of Ki-67 protein and tumor T staging. No significant relationship was found between the gender or metastasis and the expression of these two proteins. There was a positive correlation between the Lgr5 protein expression and the Ki-67 protein expression in the gastric cancer (rs=0.340, P=0.004).ConclusionsIn the development progress of gastric cancer, the Lgr5 protein might get involved in the mechanism of tumor invasion, lymph nodal metastasis, and low differentiation. Ki-67 protein might get involved in the mechanism of lymph nodal metastasis and low differentiation. The two proteins, together with the HP infection, might play a synergistic role in tumorigenesis and development.