中文摘要：

Let-7是目前研究最为广泛的microRNA家族之一。通过转录后调控机制,let-7可以特异性结合到信使RNA（mRNA）上,从而降解靶基因mRNA或抑制其翻译。研究表明,let-7家族在干细胞与肿瘤干细胞中参与多种调控机制,在维持干细胞特性（stemness）,即高增殖、低分化和自我更新能力的过程中起到重要调控作用。本文将从干细胞与肿瘤干细胞两个方面,综述let-7与细胞＂干性＂间存在的联系和调控机制。

英文摘要：

Originally discovery indicates a class of miRNA, let-7, which binds to target messenger RNAs （mRNA） through a post-transcription regulation and induces either translation repression or mRNA degradation, plays a regulatory role in the stem cells/cancer stem ceils self renewal, development, differentiation, metastasis and apoptosis. Based on these findings about let-7＇s function and its regulatory processes, this review will summarizes these processes and the potential role in the stem cell and cancer stem cell. A more complete understand of its function on stemness will thus find new solution to the research, the diagnose and therapy of human cancer.