Decreased expression of CD63 tetraspanin protein predicts elevated malignant potential in human esophageal cancer

The tetraspanin CD63 has been described to have critical roles in multiple biological processes, including tumorigenesis and metastasis in several types of cancer. However, its role in esophageal carcinoma (EC) has not been reported. In the current study, immunohistochemistry was used to investigate CD63 expression in 106 esophageal cancer samples, 49 adjacent esophagus tissues and 17 normal esophagus mucosa tissues. The results revealed that the overexpression of CD63 was observed in esophageal cancer samples and negatively correlated with tumor stage and lymph node metastasis. To further evaluate the role of CD63 in esophageal carcinoma, the invasiveness of EC cells was analyzed using matrigel invasion assays and wound healing assays in vitro. Furthermore, it was found that CD63 knockdown increased the invasiveness of TE-1 cells through the upregulation of matrix metalloproteinase (MMP) expression via promoting epithelial-mesenchymal transition. The current data therefore suggested that low levels of CD63 expression may be involved in the tumor progression of esophageal carcinoma.