High Expression of LAMP3 Is a Novel Biomarker of Poor Prognosis in Patients with Esophageal Squamous Cell Carcinoma

Lysosomal-associated membrane protein 3 (LAMP3), identified as a molecular marker of mature dendritic cells, is one of the LAMP family members. Its expression was induced by hypoxia, and was associated with hypoxia mediated metastasis in breast and cervical cancers. However, epithelial expression of LAMP3 and its prognostic value in esophageal squamous cell carcinoma (ESCC) is still unknown. In the current study, mRNA expression of LAMP3 in 157 ESCC tissues and 50 adjacent normal tissues was detected by quantitative real-time PCR (qRT-PCR). LAMP3 protein expression in 46 paired cancerous and normal tissues was detected by immunohistochemistry (IHC). Then, DNA copy number was examined to observe its potential correlation with mRNA expression. The results showed that both mRNA and protein expression level of LAMP3 was significantly higher in cancerous tissues compared with normal controls (p < 0.001). LAMP3 DNA copy number was amplified in 70% of ESCC tissues and positive correlated with mRNA expression (p = 0.037). Furthermore, patients with higher LAMP3 expression had worse overall survival (HR = 1.90, 95% CI = 1.17-3.09, p = 0.010) and disease-free survival (HR = 1.80, 95% CI = 1.18-2.74, p = 0.006). In conclusion, our results suggest that epithelial LAMP3 expression is an independent prognostic biomarker for ESCC.