EphA2 promotes infiltrative invasion of glioma stem cells in vivo through cross-talk with Akt and regulates stem cell properties.
Diffuse infiltrative invasion is a major cause for the dismal prognosis of glioblastoma multiforme (GBM), but the underlying mechanisms remain incompletely understood. Using human glioma stem cells (GSCs) that recapitulate the invasive propensity of primary GBM, we find that EphA2 critically regulates GBM invasion in vivo. EphA2 was expressed in all seven GSC lines examined, and overexpression of EphA2 enhanced intracranial invasion. The effects required Akt-mediated phosphorylation of EphA2 on serine 897. In vitro the Akt-EphA2 signaling axis is maintained in the absence of ephrin-A ligands and is disrupted upon ligand stimulation. To test whether ephrin-As in tumor microenvironment can regulate GSC invasion, the newly established Efna1;Efna3;Efna4 triple knockout mice (TKO) were used in an ex vivo brain slice invasion assay. We observed significantly increased GSC invasion through the brain slices of TKO mice relative to wild-type (WT) littermates. Mechanistically EphA2 knockdown suppressed stem cell properties of GSCs, causing diminished self-renewal, reduced stem marker expression and decreased tumorigenicity. In a subset of GSCs, the reduced stem cell properties were associated with lower Sox2 expression. Overexpression of EphA2 promoted stem cell properties in a kinase-independent manner and increased Sox2 expression. Disruption of Akt-EphA2 cross-talk attenuated stem cell marker expression and neurosphere formation while having minimal effects on tumorigenesis. Taken together, the results show that EphA2 endows invasiveness of GSCs in vivo in cooperation with Akt and regulates glioma stem cell properties.
1] Rammelkamp Center for Research, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA [2] Department of Pharmacology and Oncology, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
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Miao
VelociGene Division, Regeneron Pharmaceuticals Inc., Tarrytown, NY, USA.
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Gale
1] Rammelkamp Center for Research, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA [2] Department of Pharmacology and Oncology, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
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Guo
1] Rammelkamp Center for Research, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA [2] Department of Pharmacology and Oncology, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
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Qian
1] Rammelkamp Center for Research, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA [2] Department of Pharmacology and Oncology, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
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Petty
1] Rammelkamp Center for Research, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA [2] Department of Pharmacology and Oncology, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
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Kaspar
VelociGene Division, Regeneron Pharmaceuticals Inc., Tarrytown, NY, USA.
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Murphy
VelociGene Division, Regeneron Pharmaceuticals Inc., Tarrytown, NY, USA.
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Valenzuela
VelociGene Division, Regeneron Pharmaceuticals Inc., Tarrytown, NY, USA.
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Yancopoulos
1] Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA [2] Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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Hambardzumyan
1] Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA [2] Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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Lathia
1] Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA [2] Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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Rich
1] Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA [2] Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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Lee
1] Rammelkamp Center for Research, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH, USA [2] Department of Pharmacology and Oncology, Case Western Reserve University School of Medicine, Cleveland, OH, USA [3] Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
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B
Wang
D000818:Animals; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology; D063646:Carcinogenesis / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D005909:Glioblastoma / Q000235:genetics* / Q000473:pathology; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009361:Neoplasm Invasiveness / Q000235:genetics; D014411:Neoplastic Stem Cells / Q000473:pathology; D051058:Oncogene Protein v-akt / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation / Q000235:genetics; D036104:Receptor, EphA2 / Q000235:genetics*; D055748:SOXB1 Transcription Factors / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics
D055748:SOXB1 Transcription Factors; D036104:Receptor, EphA2; D051058:Oncogene Protein v-akt