Inhibition of Grb2 expression demonstrates an important role in BCR-ABL-mediated MAPK activation and transformation of primary human hematopoietic cells.
Inhibition of Grb2 expression demonstrates an important role in BCR-ABL-mediated MAPK activation and transformation of primary human hematopoietic cells.
复制标题
作者：
慢性髓系白血病(CML)是bcr/abl癌基因在原始造血细胞中表达的结果。然而，bcr/abl激活的信号机制依赖于其表达的细胞环境，而bcr-abl转化原始人类造血细胞的机制尚不清楚。我们以往的研究表明，bcr/abl-Y177基因在慢性粒细胞白血病RAS激活和人类造血祖细胞转化中起重要作用。适配蛋白生长因子受体结合蛋白-2(Grb2)可以结合磷酸化的bcr/abl-Y177，诱导Grb2-SOS复合体的形成，激活RAS信号。我们通过将表达shRNA的慢病毒载体和表达bcr/abl的逆转录病毒载体共转导人CD34+细胞，研究了Grb2在CML祖细胞转化中的作用。我们发现Grb2基因敲除显著抑制了表达bcr-abl的CD34+细胞的增殖和存活，但不能控制CD34+细胞。Grb2基因敲除可降低表达bcr-Abl基因的造血细胞的MAPK活性。结论：抑制Grb2的表达在bcr-abl介导的MAPK的激活和转化中起重要作用。这些结果支持进一步研究Grb2介导的信号的下游效应，并针对Grb2相互作用在CML的治疗中的作用。
Chronic myeloid leukemia (CML) results from expression of the BCR/ABL oncogene in a primitive hematopoietic cell. However BCR/ABL-activated signaling mechanisms are dependent on the cellular context in which it is expressed, and mechanisms underlying primitive human hematopoietic cell transformation by BCR-ABL are not well understood. Our previous studies have shown that BCR/ABL-Y177 plays an essential role in Ras activation and human hematopoietic progenitor transformation in CML. The adapter protein growth factor receptor binding protein-2 (Grb2) can bind phosphorylated BCR/ABL-Y177, induce Grb2-SoS complex formation, and activate Ras signaling. We investigated the role of Grb2 in CML progenitor transformation by co-transducing human CD34+ cells with lentivirus vectors expressing shRNA to Grb2 and retrovirus vectors expressing BCR/ABL. We show that Grb2 knockdown significantly inhibits proliferation and survival of BCR-ABL-expressing CD34+ cells, but not control CD34+ cells. Grb2 knockdown reduced MAPK activity in BCR-Abl-expressing hematopoietic cells. We conclude that inhibition of Grb2 expression demonstrates an important role in BCR-ABL mediated MAPK activation and transformation of primary human hematopoietic cells. These results support further investigation of downstream effectors of Grb2-mediated signals and targeting of Grb2 interactions in the treatment of CML.