MicroRNAs (miRNAs) are small non-coding RNAs that mainly act by binding to target genes to regulate their expression. Due to the multitude of genes regulated by miRNAs they have been subject of extensive research in the past few years. This state-of-the-art review summarizes the current knowledge about miRNAs and illustrates their role as powerful regulators of physiological processes. Moreover, it highlights their aberrant expression in disease, including specific cancer types and the differential hosting-metastases preferences that influence several steps of tumorigenesis. Considering the incidence of breast cancer and that the metastatic disease is presently the major cause of death in women, emphasis is put in the role of miRNAs in breast cancer and in the regulation of the different steps of the metastatic cascade. Furthermore, we depict their involvement in the cascade of events underlying breast cancer brain metastasis formation and development. Collectively, this review shall contribute to a better understanding of the uniqueness of the biologic roles of miRNAs in these processes, to the awareness of miRNAs as new and reliable biomarkers and/or of therapeutic targets, which can change the landscape of a poor prognosis and low survival rates condition of advanced breast cancer patients.

中文翻译：

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健康和疾病中的 miRNA：关注乳腺癌向大脑的转移级联。

MicroRNA (miRNA) 是一种小的非编码 RNA，主要通过与靶基因结合来调节其表达。由于 miRNA 调控的基因众多，因此它们在过去几年中一直是广泛研究的主题。这篇最先进的综述总结了当前有关 miRNA 的知识，并说明了它们作为生理过程的强大调节剂的作用。此外，它强调了它们在疾病中的异常表达，包括特定的癌症类型和影响肿瘤发生几个步骤的不同宿主转移偏好。考虑到乳腺癌的发病率以及转移性疾病目前是女性死亡的主要原因，重点关注 miRNA 在乳腺癌中的作用以及转移级联不同步骤的调节。此外，我们描述了它们参与乳腺癌脑转移形成和发展的一系列事件。总的来说，这篇综述将有助于更好地理解 miRNA 在这些过程中生物学作用的独特性，有助于认识 miRNA 作为新的可靠的生物标志物和/或治疗靶点，这可以改变不良预后的现状，晚期乳腺癌患者的生存率较低。