Global analysis of L1-transcriptomes identified IGFBP-2 as a target of ezrin and NF-κB signaling that promotes colon cancer progression
Global analysis of L1-transcriptomes identified IGFBP-2 as a target of ezrin and NF-κB signaling that promotes colon cancer progression
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DOI：
10.1038/onc.2012.340
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发表时间：
2013-07-04
期刊：
影响因子：
8
通讯作者：
Ben-Ze'ev, A.
中科院分区：
文献类型：
--
作者：
Ben-Shmuel, A.;Shvab, A.;Ben-Ze'ev, A.
L1是一种免疫球蛋白样蛋白家族的神经元细胞粘附受体，作为Wnt/ β -连环蛋白信号传导的靶基因在侵袭性结直肠癌（CRC）细胞中表达。CRC细胞中L1的过度表达增强了细胞的运动和增殖，并导致肝转移。我们最近发现ezrin和I κ B- nf - κ B通路对CRC细胞中L1赋予的生物学特性至关重要。在这里，我们研究了潜在的分子机制，发现L1通过rho相关蛋白激酶（ROCK）增强ezrin磷酸化，这是L1-ezrin在近膜区域共定位和增强细胞运动性所必需的。将表达l1的结直肠癌细胞的转录组与表达ezrin的小发夹RNA （shRNA）的相同细胞的转录组进行比较。在被L1和ezrin上调表达的基因中，我们发现了胰岛素样生长因子结合蛋白2 (IGFBP-2)，并发现其表达的增加是由nf - κ b介导的IGFBP-2基因启动子的反激活介导的。组成型激活突变ezrin （Ezrin567D）的表达也可以增加结直肠癌细胞中IGFBP-2的水平。在缺乏L1的CRC细胞中，IGFBP-2的过表达增强了细胞增殖（在缺乏血清的情况下）、细胞运动、肿瘤发生和诱导的肝转移，类似于L1的过表达。在L1转染的细胞中抑制内源性IGFBP-2可抑制L1赋予的这些特性。我们检测到IGFBP-2在正常粘膜中人类结肠隐巢底部的一个独特组织中，并且在与NF-kappa B的磷酸化p65亚基共定位的人类CRC组织样本中水平升高。最后，我们发现IGFBP-2和L1可以形成一个分子复合物，这表明L1介导的信号通路L1-ezrin-NF-kappa B诱导IGFBP-2表达，在CRC进展中起重要作用。
L1, a neuronal cell adhesion receptor of the immunoglobulin-like protein family is expressed in invading colorectal cancer (CRC) cells as a target gene of Wnt/beta-catenin signaling. Overexpression of L1 in CRC cells enhances cell motility and proliferation, and confers liver metastasis. We recently identified ezrin and the I kappa B-NF-kappa B pathway as essential for the biological properties conferred by L1 in CRC cells. Here, we studied the underlying molecular mechanisms and found that L1 enhances ezrin phosphorylation, via Rho-associated protein kinase (ROCK), and is required for L1-ezrin co-localization at the juxtamembrane domain and for enhancing cell motility. Global transcriptomes from L1-expressing CRC cells were compared with transcriptomes from the same cells expressing small hairpin RNA (shRNA) to ezrin. Among the genes whose expression was elevated by L1 and ezrin we identified insulin-like growth factor-binding protein 2 (IGFBP-2) and showed that its increased expression is mediated by an NF-kappa B-mediated transactivation of the IGFBP-2 gene promoter. Expression of a constitutively activated mutant ezrin (Ezrin567D) could also increase IGFBP-2 levels in CRC cells. Overexpression of IGFBP-2 in CRC cells lacking L1-enhanced cell proliferation (in the absence of serum), cell motility, tumorigenesis and induced liver metastasis, similar to L1 overexpression. Suppression of endogenous IGFBP-2 in L1-transfected cells inhibited these properties conferred by L1. We detected IGFBP-2 in a unique organization at the bottom of human colonic crypts in normal mucosa and at increased levels throughout human CRC tissue samples co-localizing with the phosphorylated p65 subunit of NF-kappa B. Finally, we found that IGFBP-2 and L1 can form a molecular complex suggesting that L1-mediated signaling by the L1-ezrin-NF-kappa B pathway, that induces IGFBP-2 expression, has an important role in CRC progression.