Woerner B Mark, Warrington Nicole M, Kung Andrew L, Perry Arie, Rubin Joshua B
Department of Pediatrics, Division of Pediatric Hematology/Oncology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Cancer Res. 2005 Dec 15;65(24):11392-9. doi: 10.1158/0008-5472.CAN-05-0847.
The chemokine receptor CXCR4 is expressed in many cancers where it may regulate tumor cell growth and migration. The role of CXCR4 in cancer will depend on it being in an activated, signaling state. To better define the significance of CXCR4 expression in cancer, we developed an antibody that can distinguish CXCR4 phosphorylated on serine 339, a residue previously identified as a site for ligand-induced phosphorylation. With this antibody, we investigated the mechanisms of CXCR4 phosphorylation and evaluated the phosphorylation status of CXCR4 in human astrocytomas. In vitro, phosphorylation of serine 339 occurred in response to CXCL12 or epidermal growth factor (EGF) treatment and was increased by protein kinase C activation. In all grades of astrocytomas, CXCR4 was expressed in tumor cells and some endothelial cells, whereas CXCL12 was present in endothelial cells and infiltrating microglia. We found that CXCR4 phosphorylated on serine 339 was present in tumor cells and vascular endothelial cells in all grades of astrocytoma. These data indicate that CXCR4 is expressed and activated in astrocytomas and that phosphorylation of CXCR4 can occur through ligand activation or transactivation via the EGF receptor. These studies extend the potential roles of CXCR4 in cancer to include functions associated with benign (grade 1) tumors. The ability to distinguish phosphorylated CXCR4 will be invaluable for the continued analysis of the role of CXCR4 in cancer and the development of CXCR4 antagonist therapy for patients suffering with primary tumors of the brain and other sites.
趋化因子受体CXCR4在许多癌症中表达，它可能调节肿瘤细胞的生长和迁移。CXCR4在癌症中的作用将取决于其处于激活的信号传导状态。为了更好地界定CXCR4在癌症中表达的意义，我们研发了一种抗体，该抗体能够区分丝氨酸339位点磷酸化的CXCR4，该位点先前被确定为配体诱导磷酸化的位点。利用这种抗体，我们研究了CXCR4磷酸化的机制，并评估了人星形细胞瘤中CXCR4的磷酸化状态。在体外，丝氨酸339的磷酸化是对CXCL12或表皮生长因子（EGF）处理的反应，并且通过蛋白激酶C的激活而增加。在所有级别的星形细胞瘤中，CXCR4在肿瘤细胞和一些内皮细胞中表达，而CXCL12存在于内皮细胞和浸润的小胶质细胞中。我们发现，在所有级别的星形细胞瘤中，丝氨酸339磷酸化的CXCR4存在于肿瘤细胞和血管内皮细胞中。这些数据表明，CXCR4在星形细胞瘤中表达并被激活，并且CXCR4的磷酸化可通过配体激活或经由表皮生长因子受体的转激活而发生。这些研究扩展了CXCR4在癌症中的潜在作用，使其包括与良性（1级）肿瘤相关的功能。区分磷酸化CXCR4的能力对于持续分析CXCR4在癌症中的作用以及为患有原发性脑肿瘤和其他部位肿瘤的患者开发CXCR4拮抗剂疗法将具有极高的价值。
