Plasma soluble human leukocyte antigen G predicts the long-term prognosis in patients with colorectal cancer

Colorectal cancer (CRC) is the third most common tumor in the world, ranking fourth in the cause of cancer death (1). Although 60% to 70% of colorectal cancer patients are diagnosed with locally advanced tumors at the initial diagnosis, half of the patients will eventually relapse or metastasize after radical resection (2,3). Although the effectiveness of the current comprehensive treatment of colorectal cancer is significantly improved compared with before, and the five-year survival rate is also significantly improved. However, due to the large population with CRC, there are still many patients affected by poor prognosis. Therefore, finding suitable long-term prognostic indicators is essential for monitoring patients with a high risk of poor prognosis and, therefore, to improve prognosis. Many studies have shown that changes in the body’s immune status and inflammatory response are strictly related to the occurrence, development, and prognosis of tumors (4,5). Human leukocyte antigen G (HLA-G) belongs to non-classical HLA class I molecules, and is one of the immunosuppressive molecules for innate immunity and acquired immunity. The initial transcription product can be encoded to produce seven isomers, including four membrane-bound types (HLA-G1–HLA-G4) and three soluble types (HLA-G5–HLA-G7). Also, HLA -G1 can be hydrolyzed by matrix metalloproteinases to form another soluble HLA-G1 molecule (6). HLA-G molecules can bind to their corresponding receptors, including immunoglobulin-like transcript 2 (immunoglobulin-1ike transcript 2, ILT2), immunoglobulin-like transcript 4 (immunoglobulin-like transcript 4, ILT4), and Killer cell immunoglobulin-like receptor 2DL4 (KIR2DL4) participates in tumor immune escape by inhibiting the killing of natural killer (NK), inhibiting the proliferation of effector T cells and inducing the production of Treg cells and abnormally expressed HLA-G is often associated with various malignant tumors (7). This study aims to evaluate the long-term predictive value of soluble human leukocyte antigen G (soluble HLA-G, sHLA-G) in colorectal cancer through a two-center retrospective study since no research has investigate the long-term predictive value of this molecule in patients with CRC