PIK3R1 targeting by miR-21 suppresses tumor cell migration and invasion by reducing PI3K/AKT signaling and reversing EMT, and predicts clinical outcome of breast cancer.
PIK3R1 targeting by miR-21 suppresses tumor cell migration and invasion by reducing PI3K/AKT signaling and reversing EMT, and predicts clinical outcome of breast cancer.
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miR-21 靶向 PIK3R1 通过减少 PI3K/AKT 信号传导和逆转 EMT 来抑制肿瘤细胞迁移和侵袭，并预测乳腺癌的临床结果。
DOI：
10.3892/ijo.2015.3287
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发表时间：
2016-02
影响因子：
5.2
通讯作者：
Chen J
中科院分区：
文献类型：
--
作者：
Yan LX;Liu YH;Xiang JW;Wu QN;Xu LB;Luo XL;Zhu XL;Liu C;Xu FP;Luo DL;Mei P;Xu J;Zhang KP;Chen J
我们先前已经表明，miR-21的失调在乳腺癌中起着oncomiR的作用。本研究的目的是阐明miR-21调节乳腺肿瘤迁移和侵袭的机制。我们应用基因组微阵列数据的通路分析和靶点预测算法进行miR-21靶点筛选，并使用荧光素酶报告分析来确定直接靶点。在此基础上，我们对320例乳腺癌石蜡包埋组织进行了靶基因磷酸肌醇-3-激酶调节亚基1（α）（PIK 3R 1）的功能研究，并通过免疫组化和RT-qPCR检测了PIK 3R 1编码蛋白（p85α）和miR-21的表达，以评估其表达与预后的相关性。首先，我们发现PIK 3R 1抑制乳腺癌细胞的生长、侵袭和转移特性。接下来，我们将PIK 3R 1鉴定为miR-21的直接靶点，并表明它受miR-21的负调控。此外，我们证明p85α过表达表型模拟了antimiR-21对乳腺癌细胞生长、迁移和侵袭的抑制作用，表明其在乳腺癌中的肿瘤抑制作用。相反，PIK 3R 1敲低消除了antimiR-21对乳腺癌细胞的诱导作用。值得注意的是，antimiR-21诱导增加了p85α，同时降低了p-AKT水平。此外，antimiR-21/PIK 3R 1诱导的乳腺癌细胞侵袭性抑制是通过逆转上皮间质转化（EMT）介导的。在320例乳腺癌患者中，25例（7.8%）发现p85α下调，并与较低的5年无病生存期（DFS）和总生存期（OS）相关。综上所述，我们提供了新的证据，即miR-21敲低抑制细胞生长，迁移和侵袭，部分通过抑制PI 3 K/AKT激活，通过直接靶向PIK 3R 1和逆转EMT在乳腺癌中。p85α下调定义了具有较短5年DFS和OS的特定乳腺癌亚组，其可能需要更积极的治疗。
We have previously shown that dysregulation of miR-21 functioned as an oncomiR in breast cancer. The aim of the present study was to elucidate the mechanisms by which miR-21 regulate breast tumor migration and invasion. We applied pathway analysis on genome microarray data and target-predicting algorithms for miR-21 target screening, and used luciferase reporting assay to confirm the direct target. Thereafter, we investigated the function of the target gene phosphoinositide-3-kinase, regulatory subunit 1 (α) (PIK3R1), and detected PIK3R1 coding protein (p85α) by immunohistochemistry and miR-21 by RT-qPCR on 320 archival paraffin-embedded tissues of breast cancer to evaluate the correlation of their expression with prognosis. First, we found that PIK3R1 suppressed growth, invasiveness, and metastatic properties of breast cancer cells. Next, we identified the PIK3R1 as a direct target of miR-21 and showed that it was negatively regulated by miR-21. Furthermore, we demonstrated that p85α overexpression phenocopied the suppression effects of antimiR-21 on breast cancer cell growth, migration and invasion, indicating its tumor suppressor role in breast cancer. On the contrary, PIK3R1 knockdown abrogated antimiR-21-induced effect on breast cancer cells. Notably, antimiR-21 induction increased p85α, accompanied by decreased p-AKT level. Besides, antimiR-21/PIK3R1-induced suppression of invasiveness in breast cancer cells was mediated by reversing epithelial-mesenchymal transition (EMT). p85α downregulation was found in 25 (7.8%) of the 320 breast cancer patients, and was associated with inferior 5-year disease-free survival (DFS) and overall survival (OS). Taken together, we provide novel evidence that miR-21 knockdown suppresses cell growth, migration and invasion partly by inhibiting PI3K/AKT activation via direct targeting PIK3R1 and reversing EMT in breast cancer. p85α downregulation defined a specific subgroup of breast cancer with shorter 5-year DFS and OS, which may require more aggressive treatment.