High TREM2 expression correlates with poor prognosis in gastric cancer

Triggering receptor expressed on myeloid cells 2 (TREM2) is a member of the immunoglobulin superfamily and associates with TYRO protein tyrosine kinase-binding protein at the cell membrane to form a receptor signaling complex. Gastric cancer (GC) is one of the most common human cancers in the world. We found that TREM2 expressions in GC and adjacent tissues were significantly different. The goal of this study was to measure TREM2 protein and mRNA expression levels in GC tissues and evaluate their value as potential prognostic markers. We analyzed TREM2 mRNA and protein expression by quantitative real-time polymerase chain reaction and immunohistochemistry, respectively, in 317 samples of GC tissue, matched normal tissue, or benign gastric lesions. The associations between TREM2 level and various clinicopathologic characteristics were assessed, and the correlation between TREM2 expression and prognosis of GC patients was analyzed using Oncomine and Kaplan-Meier Plotter online resources. TREM2 mRNA and protein expression levels were both significantly higher in GC compared with normal gastric tissues (P < .0001 and P < .001, respectively). Among the clinicopathological characteristics evaluated, differentiation (P < .05), N stage (P < .001), and TNM stage (P < .001) were all significantly associated with high TREM2 expression. TREM2 levels were inversely correlated with patient prognosis. Our data suggest that TREM2 expression could be an effective prognostic biomarker for GC.