Biochemistry, Biochemical Analysis & Matrix Pathobiology Res. Group, Laboratory of Biochemistry, Department of Chemistry, University of Patras, Patras 26110, Greece; Department of Gynecology and Obstetrics, Münster University Hospital, Münster 48149, Germany.
Department for Life Quality Studies, University of Bologna, Rimini 47100, Italy.
Matrix Biol. 2017 Dec;64:94-111. doi: 10.1016/j.matbio.2017.08.002. Epub 2017 Aug 8.
Even though the role of estrogen receptor alpha (ERα) in the modulation of breast cancer cells' behavior is thoroughly studied, the biological functions of its isoform, ERβ, are less elucidated. The suppression of ERβ in the aggressive ERα-negative MDA-MB-231 breast cancer cells resulted in the inhibition of epithelial to mesenchymal transition (EMT) and major changes in the basic functional properties and expression levels of certain matrix components of breast cancer cells. This arrest in metastatic potential of breast cancer cells suggests the contribution of ERβ in the induction of a more aggressive phenotype in MDA-MB-231 breast cancer cells. The epigenetic alterations are responsible for the ability of the tumor cells to metastasize. Here, we report for the first time that the suppression of ERβ in MDA-MB-231 breast cancer cells leads to significant changes in the expression profiles of specific microRNAs, including miR-10b, miR-200b and miR-145. Growth of MCF-7 and MDA-MB-231 cells in estrogen-free medium has a diverse impact on miRNA expression and the behavior of these cells, suggesting the specific effect of estradiol on the miRNA expression profile depending on the ER status of breast cancer cells. Enhanced miR-10b expression or silencing of miR-145 clearly revealed that these microRNAs can regulate the functional properties, EMT program and the expression of major matrix components known to be implicated in breast cancer aggressiveness. Our data revealed that miR-10b is strongly implicated in the regulation of functional properties, EMT program and Erk1/2 signaling in shERβ MDA-MB-231 cells, thus affecting the extracellular matrix (ECM) composition, including syndecan-1, proteolytic behavior, especially MMP2, MMP7 and MMP9 expression and subsequently the aggressiveness of these cells. Accordingly, the inhibition of miR-145 expression significantly increased the aggressiveness of shERβ MDA-MB-231 cells and induced EMT. Moreover, miR-145 inhibition resulted in important changes in the gene and protein levels of ECM mediators, such as HER2 and several MMPs, whereas it significantly increased the phosphorylated levels of Erk1/2 kinases in these cells, suggesting the crucial role of miR-145 in this signaling pathway. These novel results suggest that the alterations in cell behavior and in ECM composition caused by the suppression of ERβ in MDA-MB-231 cells are closely related to certain epigenetic miRNA-induced alterations. Targeting the ERβ-regulated miR-10b and miR-145 is a promising tool for diagnosis and pharmaceutical targeting in breast cancer.
尽管雌激素受体 α (ERα) 在调节乳腺癌细胞行为方面的作用已被深入研究，但它的异构体 ERβ 的生物学功能却知之甚少。在侵袭性 ERα 阴性 MDA-MB-231 乳腺癌细胞中抑制 ERβ，导致上皮间质转化 (EMT) 的抑制和乳腺癌细胞某些基质成分的基本功能特性和表达水平的重大变化。这种对乳腺癌细胞转移潜能的抑制提示 ERβ 在 MDA-MB-231 乳腺癌细胞诱导更侵袭表型中的作用。表观遗传改变是肿瘤细胞转移的能力的原因。在这里，我们首次报道，在 MDA-MB-231 乳腺癌细胞中抑制 ERβ 导致特定 microRNA（包括 miR-10b、miR-200b 和 miR-145）表达谱的显著变化。MCF-7 和 MDA-MB-231 细胞在无雌激素培养基中的生长对 miRNA 表达和这些细胞的行为有不同的影响，这表明雌激素对 miRNA 表达谱的特定影响取决于乳腺癌细胞的 ER 状态。增强的 miR-10b 表达或 miR-145 的沉默清楚地表明，这些 microRNA 可以调节功能特性、EMT 程序和主要基质成分的表达，这些成分已知与乳腺癌的侵袭性有关。我们的数据表明，miR-10b 在 shERβ MDA-MB-231 细胞中强烈参与调节功能特性、EMT 程序和 Erk1/2 信号转导，从而影响细胞外基质 (ECM) 组成，包括 syndecan-1、蛋白水解行为，特别是 MMP2、MMP7 和 MMP9 的表达，随后影响这些细胞的侵袭性。因此，抑制 miR-145 的表达显著增加了 shERβ MDA-MB-231 细胞的侵袭性并诱导 EMT。此外，miR-145 抑制导致 ECM 介质基因和蛋白水平的重要变化，如 HER2 和几种 MMPs，而在这些细胞中，Erk1/2 激酶的磷酸化水平显著增加，提示 miR-145 在该信号通路中的关键作用。这些新的结果表明，在 MDA-MB-231 细胞中抑制 ERβ 引起的细胞行为和 ECM 组成的改变与某些表观遗传 miRNA 诱导的改变密切相关。针对 ERβ 调节的 miR-10b 和 miR-145 是诊断和乳腺癌药物靶向的有前途的工具。
