Abstract：
MicroRNAs (miRNAs/miRs) are a type of endogenous non‑coding small RNA that regulates gene expression. miRNAs regulate gene expression at the post‑transcriptional level by targeting the 3\'‑untranslated region (3\'UTR) of cytoplasmic messenger RNAs (mRNAs). Recent research has confirmed the presence of mature miRNAs in the nucleus, which bind nascent RNA transcripts, gene promoter or enhancer regions, and regulate gene expression via epigenetic pathways. Some miRNAs have been shown to function as oncogenes or tumor suppressor genes by modulating molecular pathways involved in human cancers. Notably, a novel molecular mechanism underlying the dysregulation of miRNA expression in cancer has recently been discovered, indicating that miRNAs may be involved in tumorigenesis via a nuclear function that influences gene transcription and epigenetic states, elucidating their potential therapeutic implications. The present review article discusses the import of nuclear miRNAs, nucleus‑cytoplasm transport mechanisms and the nuclear functions of miRNAs in cancer. In addition, some software tools for predicting miRNA binding sites are also discussed. Nuclear miRNAs supplement miRNA regulatory networks in cancer as a non‑canonical aspect of miRNA action. Further research into this aspect may be critical for understanding the role of nuclear miRNAs in the development of human cancers.
摘要：
microRNAs（miRNAs/miRs）是一类内源性非编码小RNA，可调节基因表达。miRNA通过靶向细胞质信使RNA（mRNA）的3''-非翻译区（3'UTR）在转录后水平调节基因表达。最近的研究已经证实在细胞核中存在成熟的miRNAs,结合新生的RNA转录物，基因启动子或增强子区，并通过表观遗传途径调节基因表达。已显示一些miRNA通过调节涉及人类癌症的分子途径而作为癌基因或肿瘤抑制基因起作用。值得注意的是,最近发现了一种新的miRNA表达失调的分子机制,表明miRNA可能通过影响基因转录和表观遗传状态的核功能参与肿瘤发生，阐明其潜在的治疗意义。本综述文章讨论了核miRNA的进口，细胞核-细胞质转运机制和miRNA在癌症中的核功能。此外,还讨论了一些预测miRNA结合位点的软件工具。核miRNA作为miRNA作用的非规范方面补充癌症中的miRNA调控网络。对这一方面的进一步研究可能对于理解核miRNA在人类癌症发展中的作用至关重要。
