Abstract
Human leukocyte antigen **(**HLA)โG inhibits functions of immune component cells and promotes malignant cells evading from antitumor immunity. We investigated the clinical relevance of HLAโG expression in esophageal squamous cell carcinoma (ESCC). In our study, HLAโG expression in 79 primary ESCC lesions and corresponding adjacent normal tissues were analyzed with immunohistochemistry. Soluble HLAโG (sHLAโG) in plasma was detected with enzymeโlinked immunosorbent assay (ELISA) in 41 ESCC patients (including 19 caseโmatched lesions and plasma samples) and in 153 normal healthy controls. HLAโG expression was observed in 65.8% (52/79) of the ESCC lesions but not in adjacent normal esophageal tissues. HLAโG expression was more frequently observed in patients with advanced disease stage (III/IV vs. I/II, p = 0.01). Patients with HLAโG expression had a significantly worse survival, and HLAโG could be an independent prognostic factor. sHLAโG levels in plasma were significantly increased in patients compared to normal controls (median: 152.4 U/ml vs. 8.9 U/ml, p < 0.001). The area under receiverโoperating characteristic (ROC) curve for sHLAโG in plasma was 0.992. However, no significant correlation was found between sHLAโG in plasma and clinical parameters studied. In conclusion, our findings indicated that HLAโG expression in ESCC is associated with poor survival and could be a prognostic indicator. Furthermore, increased levels of sHLAโG in plasma might be a useful preoperative biomarker for diagnosis.