O10.08 * HIGH G-PROTEIN-COUPLED RECEPTORS 65 (GPR65) EXPRESSION PREDICTS A POORER SURGICAL OUTCOME OF GLIOBLASTOMA PATIENTS

OBJECTIVES: To investigate the expression and prognostic value of G-protein-coupled receptors 65 (GPR65, also known as T-cell death-associated gene 8, TDAG8) in glioblastoma patients. METHODS: We determined the expression of GPR65 using immunohistochemistry in tissue microarrays containing 102 GBM samples and 15 normal brain samples. Cumulative survival was calculated by the Kaplan-Meier method and analyzed by the log-rank test. Univariate and multivariate analyses were performed by the stepwise forward Cox regression model. RESULTS: GPR65 protein levels were significantly elevated in glioblastoma tissues compared with those of normal brain tissues for nearly 5 folds (P < 0.001). In addition to standard therapy, patients with high GPR65 protein expression had significantly shorter OS and PFS than those with low GPR65 expression (OS: 14.6 versus 22.6 months or 14.7 versus 22.6 months, p = 0.047 and 0.040, respectively; PFS: 12.5 versus 18.9 months or 12.8 versus 19.0 months, p = 0.089 and p = 0.085, respectively). In multivariate analysis, Cox regression model identified high GPR65 expression as an independent prognostic factor for OS and PFS (Hazard ration [HR] = 1.599 and 1.593; p = 0.037 and 0.034, respectively) of primary GBM patients. No adjuvant radiotherapy, small extent of resection were other three independent risk factors of poor prognosis in glioblastoma patients. CONCLUSION: High GPR65 expression occurs in a significant subset of glioblastoma patients and predicts a poorer outcome. The study identifies a potentially useful molecular marker for the categorization and targeted therapy of glioblastoma.