Expression of cystatin C and its effect on EC9706 cells in esophageal carcinoma.

OBJECTIVE To investigate the expression of cystatin C gene and its effect on the proliferation, apoptosis and invasiveness of EC9706 cells in esophageal carcinoma. METHODS 56 cases of esophageal carcinoma were randomly collected from our hospital. Samples of human esophageal carcinomas and matched normal esophageal mucosal epithelium were selected by resection operation from these patients. Expression of cathepsin B and cystatin C in these specimens were determined by immunohistochemistry and qRT-PCR. Next, lentiviral vectors of over-expression and interference for cystatin C gene were constructed, and both were transfected into EC9706 cells, and then the levels of cystatin C mRNA and protein were detected by qRT-PCR and Western blot. The effect of over and low-expressed cystatin C on the proliferation, apoptosis and invasiveness of esophageal carcinoma cells were detected by MTT assay, flow cytometry and Transwell assay. RESULTS Compared with normal esophageal epithelial tissues, mRNA and protein levels of cathepsin B and cystatin C in esophageal carcinoma tissues were significantly increased (P<0.05). Lentiviral vectors of over-expression and interference for cystatin C gene were successfully transfected into EC9706 cells. Over or low-expression cystatin C had no effect on EC9706 cells proliferation but had a reverse relationship with the apoptosis. However, cystatin C over-expression significantly decreased tumor invasiveness (P<0.05) while the invasiveness of EC9706 cells was significantly enhanced by RNAi-mediated abrogation of cystatin C gene expression (P<0.05). CONCLUSION Over-expressed cystatin C could inhibit the invasiveness of esophageal carcinoma cells.