Metastasis, is a development of secondary tumor growths at a distance from the primary site, and closely related to poor prognosis and mortality. However, there is still no effective treatment for metastatic cancer. Therefore, there is an urgent need to find an effective therapy for cancer metastasis. Plenty of evidence indicates that miR-9 can function as a promoter or suppressor in cancer metastasis and coordinate multistep of metastatic process. In this review, we summarize the different roles of miR-9 with the corresponding molecular mechanisms in metastasis of twelve common cancers and the multiple mechanisms underlying miR-9-mediated regulation of metastasis, benefiting the further research of miR-9 and metastasis, and hoping to bridge it with clinical applications.

转移是在远离原发部位的继发性肿瘤生长的发展，与不良预后和死亡率密切相关。然而，对于转移性癌症仍然没有有效的治疗方法。因此，迫切需要寻找一种有效的癌症转移疗法。大量证据表明，miR-9 可以作为癌症转移的启动子或抑制子，并协调转移过程的多步骤。在这篇综述中，我们总结了miR-9在十二种常见癌症转移中的不同作用及其相应的分子机制，以及miR-9介导的转移调控的多种机制，有助于进一步研究miR-9与转移，以及希望将其与临床应用联系起来。