Acquisition of epithelial-mesenchymal transition phenotype in the tamoxifen-resistant breast cancer cell: a new role for G protein-coupled estrogen receptor in mediating tamoxifen resistance through cancer-associated fibroblast-derived fibronectin and β1-integrin signaling pathway in tumor cells.
Acquisition of epithelial-mesenchymal transition phenotype in the tamoxifen-resistant breast cancer cell: a new role for G protein-coupled estrogen receptor in mediating tamoxifen resistance through cancer-associated fibroblast-derived fibronectin and β1-integrin signaling pathway in tumor cells.
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DOI：
10.1186/s13058-015-0579-y
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发表时间：
2015-05-21
期刊：
影响因子：
--
通讯作者：
Yang G
中科院分区：
文献类型：
--
作者：
Yuan J;Liu M;Yang L;Tu G;Zhu Q;Chen M;Cheng H;Luo H;Fu W;Li Z;Yang G
获得性他莫昔芬耐药仍然是乳腺癌内分泌治疗的主要障碍。β1-整合素是G蛋白偶联雌激素受体（GPER）的靶基因之一，GPER是一种新的雌激素受体，被认为是他莫昔芬耐药的引发剂。在这里，我们研究了β1-整合素在gper介导的乳腺癌他莫昔芬耐药中的作用。应用免疫组织化学方法对53例转移瘤和配对原发瘤中β1-整合素及上皮间质转化生物标志物的表达进行了检测。通过MTT和Transwell试验研究了β1-整合素在MCF-7细胞衍生的耐他莫昔芬（MCF-7R）亚克隆和MCF-7R β1-整合素沉默亚克隆中的功能。使用特异性抑制剂和Western blotting分析确定了相关的信号通路。GPER、β1-整合素和间充质生物标志物（vimentin和纤维连接蛋白）在转移瘤中的表达高于相应的原发肿瘤；转移灶中β1-整合素和GPER的表达模式接近。与MCF-7细胞相比，MCF-7R细胞中β1整合素的表达也有所增加。在MCF-7R细胞中，β1-整合素的上调是由GPER激动剂诱导的，并被GPER拮抗剂和GPER抑制剂阻断。此外，表皮生长因子受体/细胞外调节蛋白激酶（EGFR/ERK）信号通路参与了这种转录调节，因为这些激酶的特异性抑制剂也降低了gper诱导的β1整合素的上调。有趣的是，β1-整合素的沉默部分恢复了MCF-7R细胞对他莫昔芬的敏感性，α5β1-整合素亚基可能是导致这一现象的原因。重要的是，MCF-7R细胞中β1-整合素的下调减少了由癌症相关成纤维细胞或癌症相关成纤维细胞的产物纤维连接蛋白诱导的细胞迁移和上皮-间质转化。此外，β1整合素的下游激酶包括局灶黏附激酶、Src和AKT在MCF-7R细胞中被激活，可能参与了癌细胞和癌症相关成纤维细胞之间的相互作用。在MCF-7R细胞中，GPER/EGFR/ERK信号上调β1整合素的表达并激活下游激酶，这有助于癌症相关成纤维细胞诱导的细胞迁移和上皮-间质转化。GPER可能通过β1-整合素依赖模式与肿瘤微环境相互作用，促进了他莫昔芬耐药。因此，β1-整合素可能是改善乳腺癌患者抗激素治疗反应的潜在靶点。本文的在线版本（doi:10.1186/s13058-015-0579-y）包含补充材料，仅供授权用户使用。
Acquired tamoxifen resistance remains the major obstacle to breast cancer endocrine therapy. β1-integrin was identified as one of the target genes of G protein-coupled estrogen receptor (GPER), a novel estrogen receptor recognized as an initiator of tamoxifen resistance. Here, we investigated the role of β1-integrin in GPER-mediated tamoxifen resistance in breast cancer. The expression of β1-integrin and biomarkers of epithelial-mesenchymal transition were evaluated immunohistochemically in 53 specimens of metastases and paired primary tumors. The function of β1-integrin was investigated in tamoxifen-resistant (MCF-7R) subclones, derived from parental MCF-7 cells, and MCF-7R β1-integrin-silenced subclones in MTT and Transwell assays. Involved signaling pathways were identified using specific inhibitors and Western blotting analysis. GPER, β1-integrin and mesenchymal biomarkers (vimentin and fibronectin) expression in metastases increased compared to the corresponding primary tumors; a close expression pattern of β1-integrin and GPER were in metastases. Increased β1-integrin expression was also confirmed in MCF-7R cells compared with MCF-7 cells. This upregulation of β1-integrin was induced by agonists of GPER and blocked by both antagonist and knockdown of it in MCF-7R cells. Moreover, the epidermal growth factor receptor/extracellular regulated protein kinase (EGFR/ERK) signaling pathway was involved in this transcriptional regulation since specific inhibitors of these kinases also reduced the GPER-induced upregulation of β1-integrin. Interestingly, silencing of β1-integrin partially rescued the sensitivity of MCF-7R cells to tamoxifen and the α5β1-integrin subunit is probably responsible for this phenomenon. Importantly, the cell migration and epithelial-mesenchymal transition induced by cancer-associated fibroblasts, or the product of cancer-associated fibroblasts, fibronectin, were reduced by knockdown of β1-integrin in MCF-7R cells. In addition, the downstream kinases of β1-integrin including focal adhesion kinase, Src and AKT were activated in MCF-7R cells and may be involved in the interaction between cancer cells and cancer-associated fibroblasts. GPER/EGFR/ERK signaling upregulates β1-integrin expression and activates downstream kinases, which contributes to cancer-associated fibroblast-induced cell migration and epithelial-mesenchymal transition, in MCF-7R cells. GPER probably contributes to tamoxifen resistance via interaction with the tumor microenvironment in a β1-integrin-dependent pattern. Thus, β1-integrin may be a potential target to improve anti-hormone therapy responses in breast cancer patients. The online version of this article (doi:10.1186/s13058-015-0579-y) contains supplementary material, which is available to authorized users.
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