Abstract: Objective To investigate the expression characteristics of bone marrow stromal cell antigen 2 (BST2) gene in human laryngeal squamous cell carcinoma and its relationship with the prognosis and pathological features of patients, and to determine the effects of BST2 gene silencing on the proliferation, invasion and migration of laryngeal cancer cell lines. 
 Methods Immunohistochemistry was used to detect the differential expression of BST2 in laryngeal cancer tissues and adjacent tissues. The effects of BST2 gene silencing on cell proliferation,migration ability and invasion ability were detected by cell counting kit 8 (CCK-8) method, cell scratch test, and Transwell test, respectively. Clinical data of patients were collected to analyze the correlation between clinical parameters and the expression level of BST2 protein. Kaplan-Meier survival curve was used to compare the survival time of patients with different expressions of BST2 protein. Univariate and multivariate Cox regression analyses were used to analyze the effects of clinical characteristics on survival time of patients. The predictive value of BST2 was evaluated by receiver operating characteristic (ROC) curve. 
 Results The immunohistochemical results showed that the expression of BST2 protein in laryngeal cancer tissues was higher than that in adjacent tissues, showing significant difference (P＜0.001). In the TU686 cell line, the results of CCK-8 showed that the OD value of siRNA-3 group was 2.35±0.18 at 48 h, which was significantly lower than that of the normal control group 2.87±0.13 and negative control group 2.71±0.12 (F=16.330, P＜0.001). The cell scratch test showed that the healing rate of the BST2 gene silencing group was (15.1±3.71)% at 12 h, which was significantly lower than that of the normal control group (35.07±5.25)% and the negative control group (33.03±5.04)% (F=16.280, P=0.004); the healing rate was （30.41±4.01）% at 24 h, which was significantly lower than that of the normal control group (75.05±4.44)% and the negative control group (70.6±4.97)% (F=89.951, P＜0.001). The Tanswell experiment showed that the number of invasive cells in the BST2 gene silencing group was 82.67±2.51, which was significantly lower than that of the normal control group 134.67±2.52 and the negative control group 121.67±4.73 (F=188.314, P＜0.001).  There were significant differences in the expression of BST2 in patients with different clinical stages (P=0.032) and survival time (P＜0.001). Kaplan-Meier survival curve analysis showed that higher BST2 expression level was associated with shorter survival time (HR=5.102, P＜0.0001). Univariate analysis results showed that, clinical stage (χ2=17.383, P＜0.001), lymph node metastasis (χ2=14.928, P＜0.001) and BST2 expression level (χ2=21.165, P＜0.001) were significantly correlated with the survival time of laryngeal cancer patients. The results of multivariate COX regression model showed that, clinical stage (HR=4.228, 95%CI: 1.881-9.501, P＜0.001) and BST2 expression level (HR=4.757, 95%CI: 2.259-10.019, P＜0.001) was influencing factors of the survival time of these patients, and ROC analysis showed that the expression level of BST2 had a good predictive value for the prognosis of the patients (AUC=0.730). 
 Conclusion BST2 protein is highly expressed in laryngeal cancer tissues, and the high expression of BST2 can promote the proliferation, invasion and migration of laryngeal cancer cells. In addition, the high expression rate of BST2 is related to the survival of laryngeal cancer patients. 

Key words: laryngeal neoplasms, bone marrow stromal cell antigen 2, survival