Tim-3 Up-regulation in Patients with Gastric Cancer and Peptic Ulcer Disease

BACKGROUND: T-cell immunoglobulin and mucin domain protein-3 (Tim-3), an inhibitory immunoregulatory receptor, has been recently implicated in tumor biology and tumor-associated immune suppression. In the present study, expression of Tim-3 was evaluated in gastric cancer (GC) and peptic ulcer disease (PUD) at both mRNA and protein levels. METHODS: A total of 133 gastric tissue biopsies, comprising 43 from GC cases, 48 from PUD and 42 from non-ulcer dyspepsia (NUD) serving as controls were collected. Additionally, non-neoplastic adjacent tissue biopsies were also obtained from 6 patients with GC. Infection with Helicobacter pylori was determined by the rapid urease test for all participants and H&E staining was conducted for GC and PUD patients. Tim-3 relative mRNA expression was determined by SYBR Green based Real-Time PCR using β-actin as a reference gene. Tim-3 protein expression was also studied by immunohistochemistry in 7 GC, 7 PUD and 10 NUD tissue samples. RESULTS: Tim-3 was expressed at higher levels in GC (p=0.030) and PUD (p=0.022) cases compared to he NUD group. Among paired samples obtained from gastric cancer patients, tumor tissues showed elevated Tim-3 expression (p=0.019) in comparison with adjacent non-neoplastic biopsies. Tim-3 mRNA findings were supported by detection of more Tim-3 protein in cancerous (p=0.002) and ulcerative (p=0.01) tissues than in controls. Tim-3 was similarly expressed in H. pylori positive and negative cases. CONCLUSION: Higher Tim-3 expression in patients with gastric cancer and peptic ulcer implies that it might be involved in immune regulation and establishment of these gastrointestinal diseases. Targeted immunotherapy by blocking of inhibitory receptors like Tim-3 could be a promising approach for gastric cancer treatment.