Targeting BCR-ABL1 in Chronic Myeloid Leukemia by PROTAC-Mediated Targeted Protein Degradation
Targeting BCR-ABL1 in Chronic Myeloid Leukemia by PROTAC-Mediated Targeted Protein Degradation
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DOI：
10.1158/0008-5472.can-19-1236
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发表时间：
2019-09-15
期刊：
影响因子：
11.2
通讯作者：
Crews, Craig M.
中科院分区：
文献类型：
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作者：
Burslem, George M.;Schultz, Anna Reister;Crews, Craig M.
尽管使用癌蛋白BCR-ABL 1的ATP竞争性酪氨酸激酶抑制剂已使慢性粒细胞白血病（CML）患者获得持久的反应，但耐药性和残留白血病干细胞的问题仍然存在。为了测试BCR-ABL 1激酶的降解是否可以提供改善的反应，我们开发了一系列蛋白水解靶向嵌合体（PROTAC），其变构靶向BCR-ABL 1蛋白并招募E3连接酶Von Hippel-Lindau，导致致癌融合蛋白的泛素化和随后的降解。在表达BCR-ABL 1的人CML K562细胞和鼠Ba/F3细胞中，先导化合物GMB-475诱导了蛋白酶体的快速降解和下游生物标志物（如STAT 5）的抑制，与缺乏降解活性的非对映体对照相比，敏感性增加。值得注意的是，GMB-475抑制某些临床相关BCR-ABL 1激酶结构域点突变体的增殖，并进一步使Ba/F3 BCR-ABL 1细胞对伊马替尼的抑制作用敏感，同时证明对Ba/F3亲本细胞无毒性。反相蛋白阵列分析表明，与BCR-ABL 1降解相关的磷酸化SHP 2、GAB 2和SHC水平存在额外差异。重要的是，GMB-475降低了原代CML CD 34（+）细胞的活力并增加了细胞凋亡，在相同浓度下对健康CD 34（+）细胞没有影响。GMB-475降解BCR-ABL 1并降低原代CML干细胞中的细胞活力。总之，这些发现表明，BCR-ABL 1激酶抑制和蛋白质降解的结合可能代表了解决BCR-ABL 1依赖性耐药性的策略，并需要进一步研究持久性白血病干细胞的根除，这些干细胞既不依赖于BCR-ABL 1蛋白的存在也不依赖于BCR-ABL 1蛋白的活性。意义：CML中小分子诱导的BCR-ABL 1降解提供了优于抑制的优势，并提供了对CML干细胞生物学的见解。
Although the use of ATP-competitive tyrosine kinase inhibitors of oncoprotein BCR-ABL1 has enabled durable responses in patients with chronic myeloid leukemia (CML), issues of drug resistance and residual leukemic stem cells remain. To test whether the degradation of BCR-ABL1 kinase could offer improved response, we developed a series of proteolysis-targeting chimera (PROTAC) that allosterically target BCR-ABL1 protein and recruit the E3 ligase Von Hippel-Lindau, resulting in ubiquitination and subsequent degradation of the oncogenic fusion protein. In both human CML K562 cells and murine Ba/F3 cells expressing BCR-ABL1, lead compound GMB-475 induced rapid proteasomal degradation and inhibition of downstream biomarkers, such as STAT5, and showed increased sensitivity compared with diastereomeric controls lacking degradation activity. Notably, GMB-475 inhibited the proliferation of certain clinically relevant BCR-ABL1 kinase domain point mutants and further sensitized Ba/F3 BCR-ABL1 cells to inhibition by imatinib, while demonstrating no toxicity toward Ba/F3 parental cells. Reverse phase protein array analysis suggested additional differences in levels of phosphorylated SHP2, GAB2, and SHC associated with BCR-ABL1 degradation. Importantly, GMB-475 reduced viability and increased apoptosis in primary CML CD34(+) cells, with no effect on healthy CD34(+) cells at identical concentrations. GMB-475 degraded BCR-ABL1 and reduced cell viability in primary CML stem cells. Together, these findings suggest that combined BCR-ABL1 kinase inhibition and protein degradation may represent a strategy to address BCR-ABL1-dependent drug resistance, and warrant further investigation into the eradication of persistent leukemic stem cells, which rely on neither the presence nor the activity of the BCR-ABL1 protein for survival.Significance: Small-molecule-induced degradation of BCR-ABL1 in CML provides an advantage over inhibition and provides insights into CML stem cell biology.