Tissue microarray analysis for epithelial membrane protein-2 as a novel biomarker for gliomas.

Epithelial membrane protein-2 (EMP2) expression is noted in many human cancers. We evaluated EMP2 as a biomarker in gliomas. A large tissue microarray of lower grade glioma (WHO grades II-III, n = 19 patients) and glioblastoma (GBM) (WHO grade IV, n = 50 patients) was stained for EMP2. EMP2 expression was dichotomized to low or high expression scores and correlated with clinical data. The mean EMP2 expression was 1.68 in lower grade gliomas versus 2.20 in GBMs (P = 0.01). The percentage of samples with high EMP2 expression was greater in GBMs than lower grade gliomas (90.0 vs. 52.6%, P = 0.001). No significant difference was found between median survival among patients with GBM tumors exhibiting high EMP2 expression and survival of those with low EMP2 expression (8.38 vs. 10.98 months, P = 0.39). However, EMP2 expression ≥2 correlated with decreased survival (r = -0.39, P = 0.001). The EMP2 expression level also correlated with Ki-67 positivity (r = 0.34, P = 0.008). The mortality hazard ratio for GBM patients with EMP2 score of 3 or higher was 1.92 (CI 0.69-5.30). Our findings suggest that elevated EMP2 expression is associated with GBM. With other biomarkers, EMP2 may have use as a molecular target for the diagnosis and treatment of gliomas.