P17.12.B FEASIBILITY OF PROLYL OLIGOPEPTIDASE (PREP) AS TUMOR BIOMARKER IN GLIOBLASTOMA PATIENTS: A PILOT STUDY

Abstract BACKGROUND Prolyl oligopeptidase (PREP) is a serine protease that hydrolyzes biologically active oligopeptides on their carboxyl side. PREP has been connected with multiple physiological and pathological conditions. Moreover, increased PREP activities have been found in tumors, although its involvement in the modulation of cancer mechanism is still unclear. Thus, the identification of PREP and clarification of its clinical significance are important for improving the diagnosis and treatment of brain tumors. The purpose of this study was to analyze the expression of PREP and its diagnostic and prognostic value in patients with Glioblastoma (GBM). Materials and METHODS In this study, GBM patients and controls were enrolled and clinical data and PREP expression, from serum and biopsies, were collected. The relationships between PREP, Protein phosphatase 2A (PP2A), STAT3 and Transforming growth factor-β (TGF- β) were also analyzed from clinical data. RESULTS Our study found that PREP was significantly upregulated in the serum samples and in biopsy from GBM patients compared with controls. This upregulation was negatively correlated with survival, but significantly correlated with age and Mindbomb Homolog-1 Index (MIB1). Also, PREP expression was inversely correlated with tumor suppressor PP2A in biopsy from GBM patients, while PREP protein levels resulted to be positively correlated with STAT3 and TGF-β protein expression. CONCLUSION s: The detection of PREP in serum and biopsies have the potential to serve as diagnostic and prognostic biomarker in GBM patient. The findings may provide diagnostic and therapeutic target for GBM.