Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0017636 (glioblastoma)
 18,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eph receptor tyrosine kinases are involved in nervous system development. Eph ligands, termed ephrins, are transmembrane proteins that bind to Eph receptors, the mutual activation of which causes repulsive effects in reciprocally contacting cells. Previously, we showed that overexpression of EphB2 in glioma cells increases cell invasion. Here, expression profiles of ephrin-B family members were determined in four glioma cell lines and in invading glioblastoma cells collected by laser capture microdissection. Ephrin-B3 mRNA was up-regulated in migrating cells of four of four glioma cell lines (1.3- to 1.7-fold) and in invading tumor cells of eight of eight biopsy specimens (1.2- to 10.0-fold). Forced expression of ephrin-B3 in low expressor cell lines (U87, T98G) stimulated cell migration and invasion in vitro and ex vivo, concomitant with tyrosine phosphorylation of ephrin-B3. In high expressor cell lines (U251, SNB19), ephrin-B3 colocalized with Rac1 to lamellipodia of motile wild-type cells. Cells transfected with ephrin-B3 small interfering RNA (siRNA) showed significant morphologic change and decreased invasion in vitro and ex vivo. Depletion of endogenous ephrin-B3 expression abrogated the increase of migration and invasion induced by EphB2/Fc, indicating increased invasion is dependent on ephrin-B3 activation. Furthermore, using a Rac1-GTP pull-down assay, we showed that ephrin-B3 is associated with Rac1 activation. Reduction of Rac1 by siRNA negated the increased invasion by addition of EphB2/Fc. In human glioma specimens, ephrin-B3 expression and phosphorylation correlated with increasing tumor grade. Immunohistochemistry revealed robust staining for phosphorylated ephrin-B and ephrin-B3 in invading glioblastoma cells. These data show that ephrin-B3 expression and signaling through Rac1 are critically important to glioma invasion.
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PMID:Ephrin-B3 ligand promotes glioma invasion through activation of Rac1. 1695 Nov 61

EphA4, an Ephrins tyrosine kinase receptor, behaves as a dependence receptor (DR) by triggering cell apoptosis in the absence of its ligand Ephrin-B3. DRs act as conditional tumor suppressors, engaging cell death based on ligand availability; this mechanism is bypassed by overexpression of DRs ligands in some aggressive cancers. The pair EphA4/Ephrin-B3 favors survival of neuronal progenitors of the brain subventricular zone, an area where glioblastoma multiform (GBM) are thought to originate. Here, we report that Ephrin-B3 is highly expressed in human biopsies and that it inhibits EphA4 pro-apoptotic activity in tumor cells. Angiogenesis is directly correlated with GBM aggressiveness and we demonstrate that Ephrin-B3 also supports the survival of endothelial cells in vitro and in vivo. Lastly, silencing of Ephrin-B3 decreases tumor vascularization and growth in a xenograft mice model. Interference with EphA4/Ephrin-B3 interaction could then be envisaged as a relevant strategy to slow GBM growth by enhancing EphA4-induced cell death.
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PMID:Ephrin-B3 supports glioblastoma growth by inhibiting apoptosis induced by the dependence receptor EphA4. 2842 6