Abstract 854: Claudin-5 Expression in Tumor Cells is a Potential Prognostic Marker in Pediatric Ependymoma

Abstract Ependymomas are common pediatric brain tumors that originate from the ependymal cell layer and characterized by poor prognosis due to frequent recurrence. However, the current WHO grading system fails to accurately predict clinical behavior. In a retrospective study, we performed the immunohistochemical analysis of 35 pediatric ependymomas for critical components of the cell-cell junctions including cadherins, claudins and occludins. Surprisingly, we found that a number of supratentorial but not infratentorial ependymoma expressed high levels of the brain endothelial cell tight junction component claudin-5 in tumor cells. Interestingly, this region specific expression pattern was also found in the choroid plexus epithelium of the lateral ventricles from tumor free neonatal tissue samples. Ultrastructural studies of human ependyma from various brain regions confimed that the observed protein expression pattern results in distinct regional differences in cell-cell junction organization and thus in ependymal barrier function. Nevertheless, we observed a significant increase in overall survival in patients bearing claudin-5 expressing ependymoma cells. These findings might - at least in part - be explained by the high expression cell-cell junction proteins that can interfere with the invasive capacity of tumor cells. Our data indicates that the assessment of claudin-5 expression in ependymoma cells is a potentially useful prognostic marker in this pediatric CNS malignancy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 854.