Tetraspanin CD81 is expressed in human parotid cancer tissue and mediates cell proliferation

Abstract

ObjectiveCD81, a transmembrane protein belonging to the tetraspanin family, has recently attracted attention as a therapeutic target for cancer owing to its important role in human cancer biology; however, there is no previous knowledge regarding CD81 expression in parotid cancer. Therefore, this study aimed to investigate CD81 expression in human parotid cancer and its involvement in cell proliferation. MethodsTissue samples were collected from 36 patients with parotid cancer, including 10 with salivary duct carcinoma (SDC), 16 with mucoepidermoid carcinoma (MEC), five with adenoid cystic carcinoma (ACC), and five with carcinoma ex pleomorphic adenoma (Ca ex PA). CD81 expressions in the parotid cancer tissues were evaluated using western blotting and immunohistochemistry. Parotid cancer cell lines were established. The effect of suppressing CD81 expression by small interfering RNA (siRNA) and the effect of our anti-CD81 monoclonal antibody on the growth of parotid cancer cells were evaluated. ResultsThe immunohistochemical expressions of CD81 on tumor cell membranes were observed in the SDC and MEC tissues but not in the ACC and Ca ex PA tissues. Furthermore, inhibition of CD81 expression by siRNA suppressed the growth of parotid cancer cells, while the mouse monoclonal antibody against CD81 inhibited parotid cancer cell growth in a concentration-dependent manner. ConclusionsThe expression of CD81 was observed in the SDC and MEC tissues. Proliferation of parotid cancer tissue-derived cells was suppressed by inhibition of CD81 expression.