title: Drug binding and resistance mechanism of KIT tyrosine kinase revealed by hydrogen/deuterium exchange FTICR mass spectrometry.
abstract: Mutations of the receptor tyrosine kinase KIT are linked to certain cancers such as gastrointestinal stromal tumors (GISTs). Biophysical, biochemical, and structural studies have provided insight into the molecular basis of resistance to the KIT inhibitors, imatinib and sunitinib. Here, solution-phase hydrogen/deuterium exchange (HDX) and direct binding mass spectrometry experiments provide a link between static structure models and the dynamic equilibrium of the multiple states of KIT, supporting that sunitinib targets the autoinhibited conformation of WT-KIT. The D816H mutation shifts the KIT conformational equilibrium toward the activated state. The V560D mutant exhibits two low energy conformations: one is more flexible and resembles the D816H mutant shifted toward the activated conformation, and the other is less flexible and resembles the wild-type KIT in the autoinhibited conformation. This result correlates with the V560D mutant exhibiting a sensitivity to sunitinib that is less than for WT KIT but greater than for KIT D816H. These findings support the elucidation of the resistance mechanism for the KIT mutants.
authors.affiliation: Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310-4005, USA.
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Zhang
authors.forename: Xiu
authors.initials: X
authors.lastname: Yu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Greig
authors.forename: Ketan S
authors.initials: KS
authors.lastname: Gajiwala
authors.forename: Joe C
authors.initials: JC
authors.lastname: Wu
authors.forename: Wade
authors.initials: W
authors.lastname: Diehl
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Lunney
authors.forename: Mark R
authors.initials: MR
authors.lastname: Emmett
authors.forename: Alan G
authors.initials: AG
authors.lastname: Marshall
mesh_terms: D019943:Amino Acid Substitution; D001549:Benzamides; D001665:Binding Sites; D041961:Deuterium Exchange Measurement; D004351:Drug Resistance; D000068877:Imatinib Mesylate; D007211:Indoles / Q000737:chemistry / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D010879:Piperazines / Q000737:chemistry / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000737:chemistry* / Q000378:metabolism*; D011743:Pyrimidines / Q000737:chemistry / Q000378:metabolism; D011758:Pyrroles / Q000737:chemistry / Q000378:metabolism; D000077210:Sunitinib
chemical_list: D001549:Benzamides; D007211:Indoles; D010879:Piperazines; D011743:Pyrimidines; D011758:Pyrroles; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit; D000077210:Sunitinib