EMP3 (epithelial membrane protein 3)

Abstract

Epithelial membrane protein 3 (EMP3) has recently been proposed as a candidate tumor suppressor gene (TSG) for some kinds of solid tumors. EMP3 downregulation has been explained by its epigenetic silencing through aberrant hypermethylation of the promoter region. EMP3 repression in cancer seems to be an organspecific phenomenon, common in neuroblastoma and gliomas, relatively common in breast cancer, and rare in esophageal squamous cell carcinoma (ESCC). Among cancer-derived cell lines, it prevails in neuroblastoma, breast cancer and ESCC whereas it is rare in glioma, non-small cell lung carcnoma (NSCLC), gastric and colon cancer-derived cell lines. EMP3 expression level is associated with clinical prognosis in neuoblastoma, ESCC, NSCLC and upper urinary tract urothelial carcinoma. In contrast, EMP3 expression may be a novel marker of tumor aggressiveness in breast cancer whereas in gliomas, EMP3 represssion by aberrant hypermethylation has a prognostic signifcance. In both tumor types, however, alternative mechanisms to the EMP3 epigenetic silencing may exist to explain EMP3 down-regulation. Moreover, EMP3 may be involved in the prostate cancer suscpetibility.