EphA2 Receptor Unliganded Dimers Suppress EphA2 Pro-tumorigenic Signaling

• Published in: The Journal of biological chemistry 2015-11, Vol.290 (45), p.27271-27279
• Main Authors: Singh, Deo R., Ahmed, Fozia, King, Christopher, Gupta, Nisha, Salotto, Matt, Pasquale, Elena B., Hristova, Kalina
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Cell Movement; dimerization; HEK293 Cells; Humans; Ligands; membrane protein; Mutagenesis, Site-Directed; Oncogene Proteins - chemistry; Oncogene Proteins - genetics; Oncogene Proteins - metabolism; Osmotic Pressure; Phosphorylation; Protein Interaction Domains and Motifs; Protein Multimerization; Protein Stability; Protein Structure, Quaternary; receptor tyrosine kinase; Receptor, EphA2 - chemistry; Receptor, EphA2 - genetics; Receptor, EphA2 - metabolism; Signal Transduction; thermodynamics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M115.676866

The EphA2 receptor tyrosine kinase promotes cell migration and cancer malignancy through a ligand- and kinase-independent distinctive mechanism that has been linked to high Ser-897 phosphorylation and low tyrosine phosphorylation. Here, we demonstrate that EphA2 forms dimers in the plasma membrane of HEK293T cells in the absence of ephrin ligand binding, suggesting that the current seeding mechanism model of EphA2 activation is incomplete. We also characterize a dimerization-deficient EphA2 mutant that shows enhanced ability to promote cell migration, concomitant with increased Ser-897 phosphorylation and decreased tyrosine phosphorylation compared with EphA2 wild type. Our data reveal a correlation between unliganded dimerization and tumorigenic signaling and suggest that EphA2 pro-tumorigenic activity is mediated by the EphA2 monomer. Thus, a therapeutic strategy that aims at the stabilization of EphA2 dimers may be beneficial for the treatment of cancers linked to EphA2 overexpression. Background: The EphA2 receptor tyrosine kinase can promote cell migration and cancer malignancy in the absence of ligand binding. Results: We uncover a correlation between unliganded dimerization and tumorigenic signaling. Conclusion: EphA2 pro-tumorigenic signaling is likely mediated by the EphA2 monomer. Significance: A therapeutic strategy that aims at the stabilization of EphA2 dimers may be beneficial for the treatment of cancers linked to EphA2 overexpression.