10027-CBMS-3 POSTOPERATIVE EPILEPTOGENICITY IN GLIOBLASTOMA ARE ACHIEVED AS THE RESULT OF INTERACTIVE FLUCTUATIONS OF GLUTAMATE AND STEM CELL MARKER

Abstract BACKGROUND AND OBJECTIVE In our recent Glioblastoma multiforme (GBM) cases, postoperative epilepsy mostly occurred later than twenty-eight days after surgery. CD44, a stem cell marker, is known to relate with tumor cell invasiveness, however, little are known with epilepsy nor glutamate (Glu). We investigated the relationship between CD44 and the pathophysiology of this post operative late-phase epilepsy. MATERIALS AND METHODS A total of 10 GBM cases received surgery and postoperative treatment at our institute were divided into two groups; 4 cases of epilepsy onset, group E, and 6 cases without, group NE. In each group, the tumor was separated into core and periphery, from which Glu was measured (Amino Acid Analyzer L8900; Hitachi High-Tech Corporation) with expression of xCT, EAAT2 and CD44 examined (Western blot). The same objects were also examined on our three glioma stem-like cell (GSC) lines. In addition, we figured Factor X (F-X) as a key related factor, and evaluated the same objects on the GSCs under conditioned F-X (under submission). RESULTS Group E showed higher Glu than group NE both in the core and periphery. CD44 expression was significantly higher in group E in the periphery, and xCT was higher in group E both in the core and periphery. EAAT2 was lower in group E both in the core and periphery. Among the GSCs, GSC-2 had the highest CD44 expression while having the lowest xCT and extracellular Glu, and the highest EAAT2. In addition, CD44 knockdown in GSC-2 resulted in significant increase of xCT expression and extracellular Glu. Furthermore, changing the concentration of F-X low to high led to decreased expression of CD44 and increased xCT. CONCLUSION The postoperative epileptogenicity could be gained by the increase of Glu which results from the alterations of CD44, xCT and EAAT2. F-X could enhance the ability of Glu discharge.