Expression and clinical significance of B cell translocation gene 2 in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is widely known as a highly fatal cancer, and thus it is important to identify tumor-specific and radiosensitivity-specific markers in ESCC. B cell translocation gene 2 (BTG2) has been considered a novel tumor suppressor gene or radiotherapy sensitivity-associated gene. However, the relationship between BTG2 and ESCC development and radiotherapy sensitivity is uncertain. The present study aims to explore the expression and clinical significance of B cell translocation gene 2 (BTG2) in ESCC by analyzing the RNAseq data from the TCGA and immunohistochemical staining of ESCC samples. We found that the level of BTG2 mRNA was significantly decreased in ESCC patients, and further decreased significantly in radiotherapy resistant patients compared to sensitive patients. The positive expression rate of BTG2 protein was 56.0% (103/184) in 184 ESCC tissue samples and 84.0% (42/50) in normal esophageal mucosal samples, respectively. The positive ratios of BTG2 expression in radiotherapy-sensitive group and radiotherapy resistant group were 57.9% (22/38) and 23.5% (4/17), respectively. Furthermore, the analysis indicates that the expression level of BTG2 significantly correlated with lymph node metastasis and clinical staging in ESCC patients. A multivariate analysis with Cox regression model showed that BTG2 level was an independent risk factor affecting the prognosis of ESCC patients. Above all, the downregulation of BTG2 may be used as a molecular marker to identify and predict ESCC progression and radiosensitivity.