Abstract 3876: EphrinB3 and EphrinB4 receptors: potential therapeutic targets in glioblastoma
Authors: Sreeraman Kumar Radhika , Macaulay Robert J. B. , Rutherford Hannah C. , Barkey Natalie , Li Jiannong , Kim Jongphil , Koomen John M. , Morse David L. 
Published: July 2016

Introduction: Glioblastoma (GBM) is the most common primary malignant neoplasm of the central nervous system in adults with poor median overall survival despite advances in tumor. CD133 is a known putative cancer stem cell marker, and we aimed to identify markers in CD133+ GBM tumor initiating cell lines (CSCs) with an infiltrative phenotype that could serve as therapeutic targets.

Methods: Expression (mRNA) microarray datasets including 22,278 probes for known cell-surface markers in three CD133+ CSCs and 17 normal brain tissue lines were obtained. We identified genes with uniformly high mRNA expression, filtered for known localization at the cell-surface and for non- or low expression in normal brain. Ephrin B3 receptor (EphB3), ephrin B4 receptor (EphB4) and fibroblast growth factor receptor (FGFR1) were highly expressed. Protein expression was established by mass spectrometry using CD133+ cell line extracts and then assessed in 27 patient GBM (IDH-wildtype) tumor samples by immunohistochemistry. Expression was graded based of the percentage of cells positive and intensity of staining the tumor, interface and uninvolved brain. One-way ANOVA was used to test any group difference among any combination of two genes; Tukey honest significant difference method was used to adjust for p value for pairwise comparison in tumor locations. Spearman correlation analysis was applied to determine potential correlation co-expression EphB3 and EphB4. The Gamma statistic was used to identify correlation of intensity of staining with tumor location, and the Fisher's exact test was utilized to elucidate potential significance.

Results: High expression (&gt; 50% of cells stained) was 7/27 for EphB3, 8/27 for EphB4, and 18/27 for FGFR1. EphB3 and EphB4 are significantly associated with tissue location based on percentage of cells stained in each location (p &lt; 0.05). When compared to the uninvolved brain, EphB3 and EphB4 expression in the tumor and interface tissues were significantly higher (p&lt;0.05). EphB3 expression was significantly correlated with EphB4 expression (p &lt; 0.05) in tumor tissue, though the correlation was weak (r = 0.414) EphB3 and EphB4 intensity were positively associated with tissue location: 0.53 [0.21 - 0.86] and EphB4 0.45 [0.09 - 0.80] respectively. FGFR-1 was not associated with tumor location in terms of both percentage and intensity of staining.

Conclusion: In terms of percentage and intensity of staining at the uninvolved brain, interface and normal tissue, EphB3 and EphB4 were significantly associated with those three tissue locations. EphB3 and EphB4 were highly expressed in tumor and interface tissue relative to the normal tissue. Co-expression of EphB3 and EphB4 in tumor tissue was correlated. Evaluation with clinical parameters may disclose subsets of these tumors with varying infiltrative potential.

Citation Format: Radhika Sreeraman Kumar, Robert J. B. Macaulay, Hannah C. Rutherford, Natalie Barkey, Jiannong Li, Jongphil Kim, John M. Koomen, David L. Morse. EphrinB3 and EphrinB4 receptors: potential therapeutic targets in glioblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3876.