title: Small molecule inhibitors block Gas6-inducible TAM activation and tumorigenicity.
abstract: TAM receptors (Tyro-3, Axl, and Mertk) are a family of three homologous type I receptor tyrosine kinases that are implicated in several human malignancies. Overexpression of TAMs and their major ligand Growth arrest-specific factor 6 (Gas6) is associated with more aggressive staging of cancers, poorer predicted patient survival, acquired drug resistance and metastasis. Here we describe small molecule inhibitors (RU-301 and RU-302) that target the extracellular domain of Axl at the interface of the Ig-1 ectodomain of Axl and the Lg-1 of Gas6. These inhibitors effectively block Gas6-inducible Axl receptor activation with low micromolar IC50sin cell-based reporter assays, inhibit Gas6-inducible motility in Axl-expressing cell lines, and suppress H1299 lung cancer tumor growth in a mouse xenograft NOD-SCIDγ model. Furthermore, using homology models and biochemical verifications, we show that RU301 and 302 also inhibit Gas6 inducible activation of Mertk and Tyro3 suggesting they can act as pan-TAM inhibitors that block the interface between the TAM Ig1 ectodomain and the Gas6 Lg domain. Together, these observations establish that small molecules that bind to the interface between TAM Ig1 domain and Gas6 Lg1 domain can inhibit TAM activation, and support the further development of small molecule Gas6-TAM interaction inhibitors as a novel class of cancer therapeutics.
authors.affiliation: Rutgers University, New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, 205 South Orange Ave, Newark, NJ 07103, USA.
authors.forename: Stanley G
authors.initials: SG
authors.lastname: Kimani
authors.affiliation: Rutgers University, New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, 205 South Orange Ave, Newark, NJ 07103, USA.
authors.forename: Sushil
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Rutgers University, Cancer Institute of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08903, USA.
authors.forename: Nitu
authors.initials: N
authors.lastname: Bansal
authors.affiliation: Department of Molecular Microbiology and Immunology, and Department of Biochemistry, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Kamalendra
authors.initials: K
authors.lastname: Singh
authors.affiliation: Rutgers University, Office of Advanced Research Computing, 96 Frelinghuysen Road, Piscataway, NJ 08854, USA.|Rutgers University, Robert Wood Johnson Medical Center, Department of Pharmacology, 675 Hoes Lane, Piscataway, NJ 08854, USA.
authors.forename: Vladyslav
authors.initials: V
authors.lastname: Kholodovych
authors.affiliation: Rutgers University, New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, 205 South Orange Ave, Newark, NJ 07103, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Comollo
authors.affiliation: Rutgers University, Cancer Institute of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08903, USA.
authors.forename: Youyi
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Rutgers University, New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, 205 South Orange Ave, Newark, NJ 07103, USA.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Kotenko
authors.affiliation: Department of Molecular Microbiology and Immunology, and Department of Biochemistry, Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Stefan G
authors.initials: SG
authors.lastname: Sarafianos
authors.affiliation: Rutgers University, Cancer Institute of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08903, USA.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Bertino
authors.affiliation: Rutgers University, Cancer Institute of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08903, USA.|Rutgers University, Robert Wood Johnson Medical Center, Department of Pharmacology, 675 Hoes Lane, Piscataway, NJ 08854, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Welsh
authors.affiliation: Rutgers University, New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Cancer Center, 205 South Orange Ave, Newark, NJ 07103, USA.
authors.forename: Raymond B
authors.initials: RB
authors.lastname: Birge
mesh_terms: D000818:Animals; D001665:Binding Sites; D001835:Body Weight / Q000187:drug effects; D063646:Carcinogenesis / Q000187:drug effects*; D045744:Cell Line, Tumor; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D007555:Isoxazoles / Q000494:pharmacology*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D010879:Piperazines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D014183:Transplantation, Heterologous; D000076202:c-Mer Tyrosine Kinase / Q000737:chemistry / Q000378:metabolism*; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D007555:Isoxazoles; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D000076202:c-Mer Tyrosine Kinase; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6; C000629047:RU-301; C000629048:RU-302; C097072:MERTK protein, human; C084944:TYRO3 protein, human