Prognostic value of expression levels of miR-148a, miR-152 and HLA-G in colon cancer

Aberrant expression of human leukocyte antigen G (HLA-G), an immunosuppressive molecule, has been observed in various cancer types. The exact mechanism of HLA-G expression is unclear. HLA-G expression is associated with low expression levels of microRNA (miR)-148a and miR-152. To the best of our knowledge, the prognostic value of the expression levels of miR-148a, miR-152 and HLA-G has not been investigated in colon cancer. The aim of the present study was to investigate the relationship between the presence of HLA-G molecules and the expression levels of miR-148 and miR-152 in colon cancer. In addition, the association of both HLA-G and miR expression with survival results and clinicopathological data was determined. An immunohistochemical method was used for detection of HLA-G expression in the tumor tissues and adjacent healthy tissues of 108 patients with colon cancer. Reverse transcription-quantitative PCR was used for miR analysis. HLA-G was expressed in 82 (75.9%) of the cancer samples, and there was no staining in normal tissues. HLA-G expression >20%, which was found in 41.7% (45/108) of the patients with colon cancer, was significantly positively associated with patient survival (P=0.039). Additionally, miR-148a levels were lower in the tumor tissues compared with the adjacent healthy tissues. No differences were found for miR-152 expression. In addition, mir-148a levels were found to be significantly lower (P=0.001) in HLA-G-positive tumor tissues than HLA-G-negative tumor tissues, but no such relationship was found for miR-152 levels. The presence of HLA-G expression was associated with poor survival outcomes. HLA-G is one of the prognostic factors in colon cancer, and decreased miR-148a expression in colon cancer tissues may be associated with HLA-G-mediated carcinogenesis.