Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310-4005, USA.
Protein Sci. 2010 Apr;19(4):703-15. doi: 10.1002/pro.347.
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.
受体酪氨酸激酶 KIT 的突变与某些癌症有关，如胃肠道间质瘤（GIST）。生物物理、生化和结构研究为了解 KIT 抑制剂伊马替尼和舒尼替尼的耐药机制提供了线索。在这里，溶液相氢/氘交换（HDX）和直接结合质谱实验将静态结构模型与 KIT 多种状态的动态平衡联系起来，支持舒尼替尼以 WT-KIT 的自动抑制构象为靶点。D816H 突变使 KIT 构象平衡向激活状态移动。V560D 突变体表现出两种低能量构象：一种更灵活，类似于向激活构象移动的 D816H 突变体，另一种则不那么灵活，类似于自动抑制构象中的野生型 KIT。这一结果与 V560D 突变体对舒尼替尼的敏感性低于 WT KIT 但高于 KIT D816H 的结果相吻合。这些发现支持阐明 KIT 突变体的耐药机制。
