雌激素诱导的 miR-196a 升高通过靶向乳腺癌中的 SPRED1 促进肿瘤生长和转移。
Estrogen-induced miR-196a elevation promotes tumor growth and metastasis via targeting SPRED1 in breast cancer.
机构信息
The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, 450052, Henan, China.
Key Laboratory of Human Functional Genomics of Jiangsu Province, State Key Lab of Reproductive Medicine, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention, and Treatment Department of Pathology, Cancer Center, Department of Pathology, Nanjing Medical University, 140 Hanzhong Road, Nanjing, China.
出版信息
Mol Cancer. 2018 Apr 23;17(1):83. doi: 10.1186/s12943-018-0830-0.
BACKGROUND
Estrogen plays a critical role in breast cancer (BC) progression through estrogen receptor (ER)-mediated gene regulation. Emerging studies suggest that the malignant progress of BC cells is influenced by the cross talk between microRNAs (miRNAs) and ER-α signaling. However, the mechanism and functional linkage between estrogen and miRNAs remain unclear.
METHODS
The expression levels of miR-196a and SPRED1 in BC were tested by qRT-PCR in 46 paired BC and adjacent tissues and by the GEO datasets. The role of miR-196a in estrogen-induced BC development was examined by CCK-8 assay, wound healing assay, Matrigel invasion assay and tumorigenicity assay in nude mice. The binding site of ER-α in miR-196a promoter region was analyzed by ChIP-seq, ChIP assay and luciferase reporter assay. The potential targets of miR-196a in BC cells were explored using the luciferase reporter assay and western blot analysis, and the correlation between miR-196a and SPRED1 was analyzed by Spearman's correlation analysis in BC specimens and GEO dataset. TCGA BRCA data was used to characterize the ESR1 signatures according to MSigDB gene set.
RESULTS
The expression levels of miR-196a were higher in ER-positive (ER+) breast tumors compared to ER-negative (ER-) tumor tissue samples. Besides, miR-196a was involved in estrogen-induced BC cell proliferation, migration and invasion. Notably, the up-regulation of miR-196a was mediated by a direct interaction with estrogen receptor α (ER-α) but not estrogen receptor β (ER-β) in its promoter region, and miR-196a expression levels were positively correlated to ER-α signature scores. Furthermore, SPRED1 was a new direct target of miR-196a which participated in miR-196a-promoted BC development and was suppressed by ligand-activated ER-α signal pathway. Finally, forced expression of miR-196a induced tumor growth of MCF7 cells, while inhibition of miR-196a significantly suppressed the tumor progress in vivo.
CONCLUSIONS
Overall, the identification of estrogen/miR-196a/SPRED1 cascade will shed light on new molecular mechanism of estrogen signaling in BC development and therapy.
背景
雌激素通过雌激素受体（ER）介导的基因调控在乳腺癌（BC）的进展中起着关键作用。新的研究表明，BC 细胞的恶性进展受到 microRNAs（miRNAs）和 ER-α 信号转导之间的串扰影响。然而，雌激素和 miRNAs 之间的机制和功能联系仍不清楚。
方法
通过 qRT-PCR 在 46 对 BC 和相邻组织以及 GEO 数据集中检测 BC 中 miR-196a 和 SPRED1 的表达水平。通过 CCK-8 测定、划痕愈合测定、Matrigel 侵袭测定和裸鼠肿瘤生成测定来检测 miR-196a 在雌激素诱导的 BC 发育中的作用。通过 ChIP-seq、ChIP 测定和荧光素酶报告基因测定分析 ER-α 在 miR-196a 启动子区域的结合位点。使用荧光素酶报告基因测定和 Western blot 分析探索 BC 细胞中 miR-196a 的潜在靶标，并通过 Spearman 相关性分析在 BC 标本和 GEO 数据集中分析 miR-196a 和 SPRED1 之间的相关性。使用 TCGA BRCA 数据根据 MSigDB 基因集来表征 ESR1 特征。
结果
与 ER-阴性（ER-）肿瘤组织样本相比，miR-196a 在 ER-阳性（ER+）乳腺癌肿瘤中的表达水平更高。此外，miR-196a 参与了雌激素诱导的 BC 细胞增殖、迁移和侵袭。值得注意的是，miR-196a 的上调是通过其启动子区域与雌激素受体 α（ER-α）的直接相互作用介导的，而不是与雌激素受体 β（ER-β）的相互作用，并且 miR-196a 的表达水平与 ER-α 特征评分呈正相关。此外，SPRED1 是 miR-196a 的新的直接靶标，它参与了 miR-196a 促进的 BC 发展，并受到配体激活的 ER-α 信号通路的抑制。最后，miR-196a 的强制表达诱导 MCF7 细胞的肿瘤生长，而 miR-196a 的抑制显著抑制体内肿瘤的进展。
结论
总的来说，鉴定出的雌激素/miR-196a/SPRED1 级联将为雌激素信号在 BC 发展和治疗中的新分子机制提供启示。
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