中文摘要：

微小RNA（microRNAs,miRNAs）是一类高度保守的非编码单链RNA,通过与靶基因mRNA的3＇非编码区特异性结合,在转录后水平沉默靶基因表达,从而发挥着功能。一些研究表明miR-181a的表达与肿瘤密切相关,对肿瘤的形成、侵袭及转移起着很重要的作用。miR-181a在乳腺癌中的作用,目前还有诸多争议,一些研究表明miR-181a具有抑癌基因的作用,而另一些研究发现其具有促进肿瘤生成、转移的作用。本文就其在乳腺癌细胞中发挥作用的潜在作用机制,以及其未来临床应用可能,如作为肿瘤标志物用于早期乳腺癌诊断,评估病人化学药物治疗（以下简称化疗）敏感性,作为辅助化疗药物增强化疗敏感性药物等方面进行综述。

英文摘要：

MicroRNAs （miRNAs） are highly conserved non-coding single stranded RNAs.miRNAs participate in fundamental biological processes and pathophysiological processes by silencing their target mRNAs expression through binding to their 3 untranslated regions （3-UTRs）.Emerging studies have shown that alterations of miR-181a levels are involved in the initiation, progression and metastasis of human cancers.Some studies have indicated that miR-181a serves as tumor suppressors, and others have revealed the oncogenic roles of miR-181a.A growing number of evidence has linked the pathological role of miR-181a to breast cancer.Here, we specifically summarize the various published data of the links between miR-181a and breast cancers, and to explain the potential clinical application of miR-181a.miR-181a may be used as a clinically diagnostic biomarkers of breast cancer for early stage diagnosis, for evaluation of the chemotherapy sensitivity, and for directing the clinical treatment in patients.