Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI.
Transl Oncol. 2013 Apr;6(2):216-25. doi: 10.1593/tlo.13133. Epub 2013 Apr 1.
The signaling mediated by the chemokine receptor CXC chemokine receptor 2 (CXCR2) plays an important role in promoting the progression of many cancers, including pancreatic cancer, one of the most lethal human malignancies. CXCR2 possesses a consensus PSD-95/DlgA/ZO-1 (PDZ) motif at its carboxyl termini, which might interact with potential PDZ scaffold/adaptor proteins. We have previously reported that CXCR2 PDZ motif-mediated protein interaction is an important regulator for neutrophil functions. Here, using a series of biochemical assays, we demonstrate that CXCR2 is physically coupled to its downstream effector phospholipase C-β3 (PLC-β3) that is mediated by PDZ scaffold protein Na(+)/H(+) exchange regulatory factor 1 (NHERF1) into a macromolecular signaling complex both in vitro and in pancreatic cancer cells. We also observe that disrupting the CXCR2 complex, by gene delivery or peptide delivery of exogenous CXCR2 C-tail, significantly inhibits the biologic functions of pancreatic cancer cells (i.e., proliferation and invasion) in a PDZ motif-dependent manner. In addition, using a human pancreatic tumor xenograft model, we show that gene delivery of CXCR2 C-tail sequence (containing the PDZ motif) by adeno-associated virus type 2 viral vector potently suppresses human pancreatic tumor growth in immunodeficient mice. In summary, our results suggest the existence of a physical and functional coupling of CXCR2 and PLC-β3 mediated through NHERF1, forming a macromolecular complex that is critical for efficient and specific CXCR2 signaling in pancreatic cancer progression. Disrupting this CXCR2 complex could represent a novel and effective treatment strategy against pancreatic cancer.
趋化因子受体 CXC 趋化因子受体 2（CXCR2）介导的信号转导在促进许多癌症的进展中起着重要作用，包括胰腺癌，这是人类最致命的恶性肿瘤之一。CXCR2 在其羧基末端具有一个 PDZ 基序（PSD-95/DlgA/ZO-1）共识基序，该基序可能与潜在的 PDZ 支架/衔接蛋白相互作用。我们之前报道过，CXCR2 PDZ 基序介导的蛋白质相互作用是调节中性粒细胞功能的重要因素。在这里，我们使用一系列生化测定法证明，CXCR2 通过 PDZ 支架蛋白 Na+/H+交换调节因子 1（NHERF1）与下游效应物磷脂酶 C-β3（PLC-β3）物理偶联，形成一个在体外和胰腺癌细胞中的大分子信号复合物。我们还观察到，通过基因传递或外源性 CXCR2 C 端肽的传递破坏 CXCR2 复合物，以 PDZ 基序依赖性方式显著抑制胰腺癌细胞的生物学功能（即增殖和侵袭）。此外，我们使用人胰腺肿瘤异种移植模型表明，腺相关病毒 2 病毒载体的 CXCR2 C 端序列（包含 PDZ 基序）的基因传递可有力地抑制免疫缺陷小鼠中的人胰腺肿瘤生长。总之，我们的结果表明，通过 NHERF1 介导 CXCR2 和 PLC-β3 之间存在物理和功能偶联，形成一个大分子复合物，对于 CXCR2 在胰腺癌细胞进展中的有效和特异性信号转导至关重要。破坏这种 CXCR2 复合物可能代表针对胰腺癌的一种新的有效治疗策略。
