Novel Oncogenic Mutations of CBL in Human Acute Myeloid Leukemia That Activate Growth and Survival Pathways Depend on Increased Metabolism
Novel Oncogenic Mutations of CBL in Human Acute Myeloid Leukemia That Activate Growth and Survival Pathways Depend on Increased Metabolism
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DOI：
10.1074/jbc.m110.106161
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发表时间：
2010-10-15
影响因子：
4.8
通讯作者：
Sattler, Martin
中科院分区：
文献类型：
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作者：
Fernandes, Margret S.;Reddy, Mamatha M.;Sattler, Martin
急性髓系白血病(AML)以多种突变事件为特征，这些突变事件影响细胞的增殖、生存和分化。最近，E3泛素连接酶CBL连接序列中的α螺旋结构的功能增益突变与AML有关。我们在AML标本中发现了四个新的CBL突变，包括一个点突变(Y371H)和一个假定的剪接位点突变。对这两个CBL突变体的鉴定表明，与受体酪氨酸激酶Flt3(FMS样酪氨酸激酶3)或KIT共表达分别诱导了配体非依赖性生长或配体高反应性。表达突变型CBL的细胞生长需要Flt3的表达和活性。除了依赖于CBL的Flt3和CBL本身的磷酸化外，转化还与Akt和STAT5的激活有关，并需要小GTP酶Rho、Rac和CDc42的功能性表达。此外，这些突变导致细胞内活性氧水平的结构性升高，这通常与癌细胞中葡萄糖代谢的增加有关。用2-脱氧葡萄糖抑制己糖激酶，阻断了CBL突变体的转化活性，减少了信号机制的激活。总体而言，我们的数据表明，CBL的突变在多个水平上改变了细胞生物学，不仅需要激活受体近端的信号事件，还需要增加细胞的葡萄糖代谢。由CBL功能获得突变激活的通路可以有效地被小分子药物靶向。
Acute myeloid leukemia (AML) is characterized by multiple mutagenic events that affect proliferation, survival, as well as differentiation. Recently, gain-of-function mutations in the alpha helical structure within the linker sequence of the E3 ubiquitin ligase CBL have been associated with AML. We identified four novel CBL mutations, including a point mutation (Y371H) and a putative splice site mutation in AML specimens. Characterization of these two CBL mutants revealed that coexpression with the receptor tyrosine kinases FLT3 (Fms-like tyrosine kinase 3) or KIT-induced ligand independent growth or ligand hyperresponsiveness, respectively. Growth of cells expressing mutant CBL required expression and kinase activity of FLT3. In addition to the CBL-dependent phosphorylation of FLT3 and CBL itself, transformation was associated with activation of Akt and STAT5 and required functional expression of the small GTPases Rho, Rac, and Cdc42. Furthermore, the mutations led to constitutively elevated intracellular reactive oxygen species levels, which is commonly linked to increased glucose metabolism in cancer cells. Inhibition of hexokinase with 2-deoxyglucose blocked the transforming activity of CBL mutants and reduced activation of signaling mechanisms. Overall, our data demonstrate that mutations of CBL alter cellular biology at multiple levels and require not only the activation of receptor proximal signaling events but also an increase in cellular glucose metabolism. Pathways that are activated by CBL gain-of-function mutations can be efficiently targeted by small molecule drugs.