慢性淋巴细胞白血病(CLL)B细胞上的血管内皮生长因子(VEGF)受体与信号转导和转录激活因子1及3相互作用:对凋亡抗性的影响

VEGF receptors on chronic lymphocytic leukemia (CLL) B cells interact with STAT 1 and 3: implication for apoptosis resistance.

作者信息

Lee Y K, Shanafelt T D, Bone N D, Strege A K, Jelinek D F, Kay N E

机构信息

Department of Internal Medicine, Division of Hematology, Mayo Clinic, Rochester, MN 55905, USA.

出版信息

Leukemia. 2005 Apr;19(4):513-23. doi: 10.1038/sj.leu.2403667.

Abstract

We have previously shown that chronic lymphocytic leukemia (CLL) B cells secrete vascular endothelial growth factor (VEGF) in vitro, have constitutively active VEGF receptors R1 and R2, and respond to exogenous VEGF by specifically upregulating Mcl-1 and XIAP in association with decreased cell death. We found that epigallocatechin (EGCG) decreases VEGF receptor phosphorylation and induces apoptosis in CLL B cells. The mechanism(s) by which VEGF receptor activation increases Mcl-1 and XIAP and promotes survival remains unknown. To further define the signaling pathway mediating VEGF induction of antiapoptotic proteins in CLL B-cells, we investigated downstream effects of VEGF-VEGF receptor binding on the STAT signaling pathway. We find that CLL B cells abundantly express cytoplasmic serine phosphorylated (p)-STAT-1 and p-STAT-3, VEGF-R1/2 are physically associated with p-STAT-1 and p-STAT-3, and p-STAT-3 (but not p-STAT-1) is found in the CLL nucleus. VEGF receptor ligation selectively induces activation and perinuclear translocation of STAT 3 through receptor-mediated endocytosis. The inhibition of VEGF receptor activation with either tyrosine kinase inhibitors or VEGF neutralizing antibodies inhibit VEGF receptor phosphorylation, decrease p-STAT-3 (serine 727), Mcl-1, and induces cell death in CLL B cells. Thus, a VEGF-VEGF receptor pathway in CLL B cells can be linked to activation of STAT proteins that are able to enhance their apoptotic resistance.

摘要

我们之前已经表明,慢性淋巴细胞白血病(CLL)B细胞在体外分泌血管内皮生长因子(VEGF),具有组成性激活的VEGF受体R1和R2,并通过特异性上调Mcl-1和XIAP以及减少细胞死亡来对外源性VEGF作出反应。我们发现表没食子儿茶素(EGCG)可降低VEGF受体磷酸化并诱导CLL B细胞凋亡。VEGF受体激活增加Mcl-1和XIAP并促进存活的机制尚不清楚。为了进一步确定介导VEGF诱导CLL B细胞中抗凋亡蛋白的信号通路,我们研究了VEGF-VEGF受体结合对STAT信号通路的下游效应。我们发现CLL B细胞大量表达细胞质丝氨酸磷酸化(p)-STAT-1和p-STAT-3,VEGF-R1/2与p-STAT-1和p-STAT-3在物理上相关联,并且在CLL细胞核中发现了p-STAT-3(而非p-STAT-1)。VEGF受体连接通过受体介导的内吞作用选择性地诱导STAT 3的激活和核周转位。用酪氨酸激酶抑制剂或VEGF中和抗体抑制VEGF受体激活可抑制VEGF受体磷酸化,降低p-STAT-3(丝氨酸727)、Mcl-1,并诱导CLL B细胞死亡。因此,CLL B细胞中的VEGF-VEGF受体途径可与能够增强其抗凋亡能力的STAT蛋白激活相关联。

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