TGF-β Negatively Regulates CXCL1 Chemokine Expression in Mammary Fibroblasts through Enhancement of Smad2/3 and Suppression of HGF/c-Met Signaling Mechanisms.
TGF-β Negatively Regulates CXCL1 Chemokine Expression in Mammary Fibroblasts through Enhancement of Smad2/3 and Suppression of HGF/c-Met Signaling Mechanisms.
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DOI：
10.1371/journal.pone.0135063
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Cheng N
中科院分区：
文献类型：
--
作者：
Fang WB;Mafuvadze B;Yao M;Zou A;Portsche M;Cheng N
成纤维细胞是乳腺癌间质的主要细胞成分，并影响上皮细胞的生长、存活和侵袭。与正常组织成纤维细胞相比，癌相关成纤维细胞（CAF）显示出包括生长因子和细胞因子在内的许多可溶性因子的表达增加。然而，这些因素的表达调控机制仍然知之甚少。最近的研究表明，乳腺CAFs过度表达趋化因子CXCL 1，这是肿瘤侵袭和化疗耐药性的关键调节因子。CAFs中CXCL 1表达增加与患者预后不良相关，并与TGF-β信号传导成分表达减少相关。这些研究的目的是利用细胞培养和生物化学方法了解TGF-β在调节CAFs中CXCL 1表达中的作用。我们发现TGF-β处理通过Smad 2/3依赖性机制降低CAFs中CXCL 1的表达。染色质免疫沉淀和定点突变分析揭示了两个新的结合位点在CXCL 1启动子重要的Smad 2/3调制CXCL 1的表达。Smad 2/3蛋白还负调控肝细胞生长因子（HGF）的表达，发现HGF通过c-Met受体依赖性机制正调控CAFs中CXCL 1的表达。CAFs中的HGF/c-Met信号是NF-κB活性所必需的，NF-κ B是CXCL 1表达的转录激活因子。这些研究表明，TGF-β通过与启动子结合的Smad 2/3和通过抑制HGF/c-Met自分泌信号负调控CAFs中CXCL 1的表达。这些研究揭示了TGF-β和HGF（关键肿瘤促进因子）如何调节CAFs中CXCL 1趋化因子表达的新见解。
Fibroblasts are major cellular components of the breast cancer stroma, and influence the growth, survival and invasion of epithelial cells. Compared to normal tissue fibroblasts, carcinoma associated fibroblasts (CAFs) show increased expression of numerous soluble factors including growth factors and cytokines. However, the mechanisms regulating expression of these factors remain poorly understood. Recent studies have shown that breast CAFs overexpress the chemokine CXCL1, a key regulator of tumor invasion and chemo-resistance. Increased expression of CXCL1 in CAFs correlated with poor patient prognosis, and was associated with decreased expression of TGF-β signaling components. The goal of these studies was to understand the role of TGF-β in regulating CXCL1 expression in CAFs, using cell culture and biochemical approaches. We found that TGF-β treatment decreased CXCL1 expression in CAFs, through Smad2/3 dependent mechanisms. Chromatin immunoprecipitation and site-directed mutagenesis assays revealed two new binding sites in the CXCL1 promoter important for Smad2/3 modulation of CXCL1 expression. Smad2/3 proteins also negatively regulated expression of Hepatocyte Growth Factor (HGF), which was found to positively regulate CXCL1 expression in CAFs through c-Met receptor dependent mechanisms. HGF/c-Met signaling in CAFs was required for activity of NF-κB, a transcriptional activator of CXCL1 expression. These studies indicate that TGF-β negatively regulates CXCL1 expression in CAFs through Smad2/3 binding to the promoter, and through suppression of HGF/c-Met autocrine signaling. These studies reveal novel insight into how TGF-β and HGF, key tumor promoting factors modulate CXCL1 chemokine expression in CAFs.