中文摘要：

小RNA（microRNA,miRNA）是近年发现的一类内源性非编码单链RNA,在转录后水平对基因表达发挥负调控作用,参与细胞生长、发育、凋亡等重要生物过程.研究发现miRNA-21在肿瘤的发生发展过程中扮演着非常重要的角色,在不同类型肿瘤中的表达均出现明显上升,与肿瘤细胞的增殖、侵袭、血管的生成和抗药性等生物学行为相关.本文将从miRNA-21的表达与定位、对靶基因的调控以及对miRNA-21的转录调控等方面进行综述.

英文摘要：

MicroRNAs （mRNAs） are a class of endogenous small noncoding single-stranded RNAs that negatively regulate gene expression at the post-transcriptional level. MicroRNAs are involved in diverse biological processes, including development, cell differentiation and cell death. It was found that miRNA-21 played an important role in the course of oncogenesis. The expression of miRNA-21 is significantly upregulated in different kinds of solid tumors. It is involved in cell proliferation, cell invasiveness, angiogenesis and other biological behaviors. This review summarizes the current knowledge concerning the expression and location of miRNA-21 and the regulatory network related to miRNA-21 in cancer.