Human leucocyte antigen‐G 14‐bp InDel polymorphism and oral squamous cell carcinoma risk in Chinese Han population: A case–control study

Human leucocyte antigen‐G (HLA‐G) is a nonclassical HLA class I molecule involved in tumour immune escape. The purpose of this study was to investigate the association between the 14‐bp insertion/deletion (InDel) polymorphism in the 3′ untranslated region (3′‐UTR) of HLA‐G gene and oral squamous cell carcinoma (OSCC) risk in Chinese Han population (216 cases and 193 healthy controls), and furthermore, to evaluate serum soluble HLA‐G (sHLA‐G) levels in the OSCC patients. Our results demonstrated that the Ins allele was significantly less frequent in the OSCC patients than that in the healthy controls (odds ratio [OR] = 0.75; 95% confidence interval [CI]: 0.57–0.99; p = 0.040). Distribution of the 14‐bp genotypes in the OSCC patients and the healthy controls revealed that the Ins/Ins genotype was associated with decreased OSCC risk in both the codominant model (Ins/Ins versus Del/Del; OR = 0.57; 95% CI = 0.33–0.99; p = 0.044) and the log‐additive model (OR = 0.76; 95% CI: 0.58–0.99; p = 0.044). The serum sHLA‐G level was significantly higher in the OSCC patients than those in the healthy controls (p < 0.001). Receiver operating characteristic (ROC) curve revealed the valuable diagnostic value of sHLA‐G for OSCC detection, with an area under the ROC curve (AUC) of 0.891 (95% CI: 0.856–0.925, p < 0.001). The OSCC patients with Ins/Ins genotype had lower serum sHLA‐G levels than those with Ins/Del and Del/Del genotypes (p = 0.015). Furthermore, serum sHLA‐G levels were significantly increased with the increasing TNM stages of the OSCC patients (p = 0.017). Our findings revealed that the HLA‐G 14‐bp InDel polymorphism might be a genetic risk factor for OSCC susceptibility, and the serum sHLA‐G may act as a promising biomarker for noninvasive diagnosis of OSCC.