EGR-1 is Regulated by N-Methyl-D-Aspartate-Receptor Stimulation and Associated with Patient Survival in Human High Grade Astrocytomas
Early growth response-1 (EGR-1) is considered a central regulator in tumor cell proliferation, migration and angiogenesis and a promising candidate for gene therapy in human astrocytomas. However, conflicting data have been reported suggesting that both tumor promoting and anti-tumor activity of EGR-1 and its regulation, expression and prognostic significance still remain enigmatic. Our study explored EGR-1 expression and regulation in astrocytomas and its association with patient survival. As we detected two EGR-1 mRNA variants, one containing a N-methyl-D-aspartate-receptor (NMDA-R) responsive cytoplasmic polyadenylation element (CPE), further experiments were performed to determine the functional role of this pathway. After NMDA stimulation of SV-FHAS and neoplastic astrocytes, real-time polymerase chain reaction showed an increase of the CPE, containing EGR-1 splice variant only in astrocytoma cells. The surface expression and functionality of NMDA-R were demonstrated by flow cytometric analysis and measurement of increased intracellular Ca2+. EGR-1 was mainly restricted to tumor cells expressing NMDA-R and significantly up-regulated in astrocytic tumors compared with normal brain. Further, EGR-1 expression was significantly (P < 0.007) associated with enhanced patient survival and was an independent prognostic factor in multivariate analysis in high grade astrocytomas. The NMDA-R-mediated EGR-1 expression, therefore, seems to be a promising target for novel clinical approaches to astrocytoma treatment.
Document Type: Research Article
Affiliations: 1: Institute of Pathology, University of Heidelberg, Heidelberg, Germany. 2: Department of Physiology, University of Tübingen, Tübingen, Germany. 3: Children's Hospital, University of Tübingen, Tübingen, Germany. 4: Institute of Brain Research, University of Tübingen, Tübingen, Germany. 5: Department of Neurosurgery, University Hospital of Zürich, Zürich, Switzerland. 6: Department of General Neurology and Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany. 7: Medical Clinic, Sports Medicine, University of Tübingen, Tübingen, Germany.
Publication date: April 1, 2009