Gotoh A, Miyazawa K, Ohyashiki K, Tauchi T, Boswell H S, Broxmeyer H E, Toyama K
First Department of Internal Medicine, Tokyo Medical College, Japan.
Exp Hematol. 1995 Oct;23(11):1153-9.
Focal adhesion kinase (p125FAK; FAK) is a protein tyrosine kinase that is tyrosine-phosphorylated in response to v-src-mediated transformation, cell adhesion, and stimulation with neuropeptides. To elucidate a possible functional relationship between FAK and BCR-ABL oncoprotein detected in Philadelphia chromosome-positive (Ph+) leukemias, we investigated the tyrosine phosphorylation state of FAK in a murine growth factor-dependent cell line and in its stable human bcr-abl cDNA transfectant. In interleukin-3 (IL-3)-dependent NFS/N1.H7 cells, tyrosine phosphorylation of FAK was not detected after stimulation with either IL-3 or Steel factor (SLF), both of which involve Ras-mediated signaling pathways. However, stable gene transfection with p210bcr-abl cDNA into H7 cells made these cells growth factor-independent for proliferation and resulted in constitutive tyrosine phosphorylation and kinase activation of FAK. Constitutive phosphorylation and activation of FAK was also observed in all Ph+ leukemia cell lines examined--that is, K562, TS9;22, and YS9;22, which express p210BCR-ABL, and NALM-21 and OM9;22, which express p185BCR-ABL. Ph-negative (Ph-) cell lines, such as MO7e and JM, did not show any detectable tyrosine phosphorylation of FAK. FAK phosphorylation in BCR-ABL-expressing cells was inhibited in a dose-dependent manner by cytochalasin D, a reagent that disrupts the intracellular network of actin filaments. However, no suppression of kinase activity or protein expression of BCR-ABL was observed after treatment with cytochalasin D. A physical association between BCR-ABL and FAK was not apparent. These data suggest that BCR-ABL may be involved in the activation of FAK. Moreover, FAK may be distinct from components in Ras-mediated signaling cascades that are activated by stimulation of myeloid cells with various cytokines.
粘着斑激酶（p125FAK；FAK）是一种蛋白质酪氨酸激酶，在受到v-src介导的转化、细胞粘附以及神经肽刺激时会发生酪氨酸磷酸化。为了阐明FAK与在费城染色体阳性（Ph+）白血病中检测到的BCR-ABL癌蛋白之间可能存在的功能关系，我们研究了FAK在小鼠生长因子依赖性细胞系及其稳定的人bcr-abl cDNA转染细胞中的酪氨酸磷酸化状态。在白细胞介素-3（IL-3）依赖性NFS/N1.H7细胞中，用IL-3或Steel因子（SLF）刺激后均未检测到FAK的酪氨酸磷酸化，这两种因子均涉及Ras介导的信号通路。然而，将p210bcr-abl cDNA稳定转染到H7细胞中，使这些细胞在增殖时不依赖生长因子，并导致FAK的组成型酪氨酸磷酸化和激酶激活。在所有检测的Ph+白血病细胞系中也观察到了FAK的组成型磷酸化和激活，即表达p210BCR-ABL的K562、TS9;22和YS9;22，以及表达p185BCR-ABL的NALM-21和OM9;22。Ph阴性（Ph-）细胞系，如MO7e和JM，未显示出任何可检测到的FAK酪氨酸磷酸化。用细胞松弛素D（一种破坏肌动蛋白丝细胞内网络的试剂）以剂量依赖性方式抑制了表达BCR-ABL的细胞中FAK的磷酸化。然而，用细胞松弛素D处理后未观察到BCR-ABL激酶活性或蛋白表达的抑制。BCR-ABL与FAK之间未发现明显的物理关联。这些数据表明BCR-ABL可能参与了FAK的激活。此外，FAK可能与Ras介导的信号级联反应中的成分不同，后者通过用各种细胞因子刺激髓系细胞而被激活。
