Tumor-specific upregulation of human leukocyte antigen-G expression in bladder transitional cell carcinoma

Human leukocyte antigen-G (HLA-G) is a potent immunosuppressive molecule that induces functional silencing of both innate and adaptive immune responses. The relevance of the aberrant HLA-G expression in malignant contexts has been intensively investigated. However, its expression status and clinical significance in bladder cancer remain to be elucidated. In the current study, HLA-G expression in 75 primary bladder transitional cell carcinoma (TCC) lesions was analyzed with immunohistochemistry, and relationship between HLA-G expression and clinical parameters, including disease stage was evaluated. Plasma soluble HLA-G levels were analyzed in 15 TCC patients and 109 normal controls. Data revealed that HLA-G was expressed in 68.0% (51/75) primary TCC lesions, whereas it was undetectable in adjacent normal bladder tissues. The proportion of HLA-G expression in TCC samples varied from negative to 100%, and no significant association was observed for the HLA-G expression status with the patient age, gender, and disease stage. Furthermore, no significance for sHLA-G levels was observed between the TCC patients and normal controls (median 10.75 vs 8.69 U/ml, p = 0.578). Given its immunotolerant properties, our finding suggested that lesion HLA-G expression upregulated in bladder TCC lesions might be an additional mechanism for tumor cells evading from host immunosurveillance; however, its clinical relevance needs further investigation.