Document Type : Research Articles
Department of Immunology, Shiraz University of Medical Sciences, Shiraz, Iran.
Department of Pathology, Shiraz University of Medical Sciences, Shiraz, Iran.
Institute for Cancer Research, Shiraz University of Medical Sciences, Shiraz, Iran.
Background: Overexpression of human leukocyte antigen G (HLA-G) and increased plasma levels of soluble
HLA-G (sHLA-G) have been reported in different human malignancies, and are believed to be involved in tumor immune
evasion. Objectives: This study was designed to evaluate the expression of HLA-G in tumor tissues and the plasma
levels of sHLA-G in patients with gastrointestinal cancer, and to determine their associations with clinicopathological
factors. The link between Helicobacter pylori infection and increased HLA-G expression or sHLA-G levels was also
investigated in patients with gastric cancer. Methods: HLA-G expression was investigated in tumor tissues from 100
patients with gastric and colorectal adenocarcinoma using immunohistochemistry test, and plasma levels of sHLA-G
were measured in 82 patients with ELISA method. The presence of H. pylori genome was investigated in tumor
tissues from 25 patients with gastric cancer by PCR method. Results: HLA-G expression was observed in 43% of
colorectal cancers and 34.6% of gastric cancers, and was not related with any of the clinicopathological factors. There
was a significant correlation between increased sHLA-G level and stage I tumors. Eight of 25 (32%) gastric cancer
specimens were positive for H. pylori, of which 3 samples were positive for HLA-G. Soluble HLA-G levels were above
the cut-off value in all H. pylori-positive patients. Conclusion: Plasma levels of sHLA-G were significantly increased
in our patients with a sensitivity of 89% and a specificity of 62%. Soluble HLA-G level can be considered a useful
indicator for the early diagnosis of gastric and colorectal adenocarcinoma.