突变型 FMS 样酪氨酸激酶 3 的选择性降解需要 BIM 依赖性的热休克蛋白消耗。
Selective degradation of mutant FMS-like tyrosine kinase-3 requires BIM-dependent depletion of heat shock proteins.
发表日期：2024 Sep 17
作者：
Melisa Halilovic, Mohamed Abdelsalam, Joanna Zabkiewicz, Michelle Lazenby, Caroline Alvares, Matthias Schmidt, Walburgis Brenner, Sara Najafi, Ina Oehme, Christoph Hieber, Yanira Zeyn, Matthias Bros, Wolfgang Sippl, Oliver H Krämer
来源：
LEUKEMIA
摘要：
FMS 样酪氨酸激酶 3 (FLT3-ITD) 的内部串联重复是急性髓系白血病 (AML) 的常见突变。诱导突变 FLT3 蛋白酶体降解的蛋白水解靶向嵌合体 (PROTAC) 成为创新的药理学方法。控制泛素蛋白酶体系统之外的靶向蛋白水解的分子机制尚不清楚，PROTAC 是唯一已知的 FLT3 降解剂类型。我们报道基于 von-Hippel-Lindau 泛素连接酶的 FLT3 PROTAC MA49 (melotinib-49) 和 FLT3 疏水标记分子 MA50 (halotinib-50) 减少内质网相关的致癌性 FLT3-ITD，但保留 FLT3。纳摩尔剂量的 MA49 和 MA50 使用 FLT3-ITD 诱导人白血病细胞系和原代 AML 母细胞凋亡 (p< 0.05-0.0001)，但不诱导原代造血干细胞和分化免疫细胞、FLT3 野生型细胞、视网膜细胞、和c-KIT依赖性细胞。 MA49 针对 FLT3-ITD 阳性白血病细胞的体内活性在斑马鱼模型中得到验证。降解剂诱导的 FLT3-ITD 丢失涉及促凋亡 BH3 蛋白 BIM 和先前未识别的降解剂诱导的蛋白质折叠伴侣的损耗。 HSP90 和 HSP110 的表达水平与 AML 患者生存率降低相关 (p<0.1)，HSP90、HSP110 和 BIM 与原代 AML 细胞中 FLT3 的表达相关 (p<0.01)。 HSP90 抑制降解剂引起的 FLT3-ITD 消除，从而建立机械定义的反馈电路。© 2024。作者。
Internal tandem duplications in the FMS-like tyrosine kinase-3 (FLT3-ITD) are common mutations in acute myeloid leukemia (AML). Proteolysis-targeting chimeras (PROTACs) that induce proteasomal degradation of mutated FLT3 emerge as innovative pharmacological approach. Molecular mechanisms that control targeted proteolysis beyond the ubiquitin-proteasome-system are undefined and PROTACs are the only known type of FLT3 degraders. We report that the von-Hippel-Lindau ubiquitin-ligase based FLT3 PROTAC MA49 (melotinib-49) and the FLT3 hydrophobic tagging molecule MA50 (halotinib-50) reduce endoplasmic reticulum-associated, oncogenic FLT3-ITD but spare FLT3. Nanomolar doses of MA49 and MA50 induce apoptosis of human leukemic cell lines and primary AML blasts with FLT3-ITD (p < 0.05-0.0001), but not of primary hematopoietic stem cells and differentiated immune cells, FLT3 wild-type cells, retinal cells, and c-KIT-dependent cells. In vivo activity of MA49 against FLT3-ITD-positive leukemia cells is verified in a Danio rerio model. The degrader-induced loss of FLT3-ITD involves the pro-apoptotic BH3-only protein BIM and a previously unidentified degrader-induced depletion of protein-folding chaperones. The expression levels of HSP90 and HSP110 correlate with reduced AML patient survival (p < 0.1) and HSP90, HSP110, and BIM are linked to the expression of FLT3 in primary AML cells (p < 0.01). HSP90 suppresses degrader-induced FLT3-ITD elimination and thereby establishes a mechanistically defined feed-back circuit.© 2024. The Author(s).