Systematic Profiling of Mitogen-Inducible Gene 6 and Its Derived Peptides Binding to Receptor Tyrosine Kinases in Bone Cancers at Molecular and Cellular Levels

Mitogen-inducible gene 6 (Mig6) is a tumor suppressor that inactivates oncogenic kinases by disrupting the dimerization of kinase domain using its segment 1 (SGT1). Traditionally, Mig6 has been documented as a cognate binder of the ErbB family of receptor tyrosine kinases (RTKs). Considering that the kinase domains of RTKs are highly conserved that share significant homology in sequence, structure and function, we herein assumed that the Mig6 SGT1 should not only bind to ErbBs, but can also target and then inhibit other RTKs in bone cancers and bone cancer pain. In this study, we systematically profiled the binding behavior of Mig6 SGT1 segment peptide against various ontology-enriched RTKs that are semantically relevant with bone cancers. A variety of RTKs were computationally identified as the potential binding hits of Mig6 SGT1; most of them have been previously reported to be involved in the cell signaling pathways of bone cancer pathogenesis. Binding analysis further revealed that the VEGFR1 and VEGFR2 kinases are two potent binders of Mig6 SGT1, which are comparable with or even stronger than the EGFR, while other two FGFR1 and FGFR2 kinases were also observed to have a moderate potency to Mig6 SGT1. Interaction modeling and dynamics simulation revealed that the full-length Mig6 SGT1 segment contains three hotspot sub-peptide fragments sbpt1, sbpt2 and sbpt3, which are primarily responsible for SGT1 binding to RTKs and can interact with the kinase dimerization interface in an independent manner. The sbpt2 was found as a moderately potent binder of VEGFR1 kinase domain at molecular level, while the Mig6 SGT1 and its derived sbpt1 and sbpt2 were observed to have similar suppressing effects on human osteosarcoma at cellular level.