title: An engineered Axl 'decoy receptor' effectively silences the Gas6-Axl signaling axis.
abstract: Aberrant signaling through the Axl receptor tyrosine kinase has been associated with a myriad of human diseases, most notably metastatic cancer, identifying Axl and its ligand Gas6 as important therapeutic targets. Using rational and combinatorial approaches, we engineered an Axl 'decoy receptor' that binds Gas6 with high affinity and inhibits its function, offering an alternative approach from drug discovery efforts that directly target Axl. Four mutations within this high-affinity Axl variant caused structural alterations in side chains across the Gas6-Axl binding interface, stabilizing a conformational change on Gas6. When reformatted as an Fc fusion, the engineered decoy receptor bound Gas6 with femtomolar affinity, an 80-fold improvement compared to binding of the wild-type Axl receptor, allowing effective sequestration of Gas6 and specific abrogation of Axl signaling. Moreover, increased Gas6 binding affinity was critical and correlative with the ability of decoy receptors to potently inhibit metastasis and disease progression in vivo.
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California, USA.
authors.forename: Mihalis S
authors.initials: MS
authors.lastname: Kariolis
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford University, Stanford, California, USA.
authors.forename: Yu Rebecca
authors.initials: YR
authors.lastname: Miao
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California, USA.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Jones
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California, USA.
authors.forename: Shiven
authors.initials: S
authors.lastname: Kapur
authors.affiliation: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California, USA.
authors.forename: Irimpan I
authors.initials: II
authors.lastname: Mathews
authors.affiliation: Department of Radiation Oncology, Stanford University School of Medicine, Stanford University, Stanford, California, USA.
authors.forename: Amato J
authors.initials: AJ
authors.lastname: Giaccia
authors.affiliation: 1] Department of Bioengineering, Stanford University, Stanford, California, USA. [2] Department of Chemical Engineering, Stanford University, Stanford, California, USA.
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Cochran
mesh_terms: D000818:Animals; D001665:Binding Sites; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D005818:Genetic Engineering; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology* / Q000627:therapeutic use; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009362:Neoplasm Metastasis / Q000188:drug therapy; D009374:Neoplasms, Experimental / Q000188:drug therapy / Q000473:pathology; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013329:Structure-Activity Relationship; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6
chemical_list: D007141:Immunoglobulin Fc Fragments; D036341:Intercellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6