MicroRNAs, short non-coding single-stranded RNAs, are important regulators and gatekeepers of the coding genes in the human genome. MicroRNAs are highly conserved among species and expressed in different tissues and cell types. They are involved in almost all the biological processes as apoptosis, proliferation, cell cycle arrest and differentiation. Playing all these roles, it is not surprising that the deregulation of the microRNA profile causes a number of diseases including cancer. Breast cancer, the most commonly diagnosed malignancy in women, accounts for the highest cancer-related deaths worldwide. Different microRNAs were shown to be up or down regulated in breast cancer. MicroRNAs can function as oncogenes or tumor suppressors according to their targets. In this review, the most common microRNAs implicated in breast cancer are fully illustrated with their targets. Besides, the review highlights the effect of exosomal microRNA on breast cancer and the effect of microRNAs on drug and therapies resistance as well as the miRNA-based therapeutic strategies used until today.

MicroRNA是短的非编码单链RNA，是人类基因组中编码基因的重要调节剂和关守者。MicroRNA在物种之间高度保守，并在不同的组织和细胞类型中表达。它们参与几乎所有的生物学过程，例如凋亡，增殖，细胞周期停滞和分化。发挥所有这些作用，microRNA谱的失调会引起包括癌症在内的许多疾病就不足为奇了。乳腺癌是女性中最常被诊断出的恶性肿瘤，在全球范围内，与癌症相关的死亡人数最高。在乳腺癌中显示出不同的微RNA被上调或下调。MicroRNA可以根据其目标充当癌基因或抑癌基因。在这篇评论中 涉及乳腺癌的最常见microRNA及其靶标已得到充分说明。此外，综述重点介绍了外泌体microRNA对乳腺癌的影响以及microRNA对药物和治疗耐药性的影响，以及直至今天为止所使用的基于miRNA的治疗策略。