Increasing studies have revealed the importance of microRNAs (miRNAs) in tumorigenesis and tumor progression. miR-455-3p is a newly identified tumor suppressive RNA in various human cancers. However, the expression pattern and clinical significance of miR-455-3p in colorectal cancer (CRC) remains unclear. We found that expression of miR-455-3p was significantly reduced in CRC tissues and cell lines. In addition, we show that low miR-455-3p expression is associated with larger tumor size, advanced tumor stage, and poorer overall survival of CRC patients. Furthermore, in vitro experiments revealed that overexpression of miR-455-3p represses cell proliferation. Importantly, we show that the tumor protein translationally controlled 1 (TPT1) is a direct target of miR-455-3p. Moreover, expression of TPT1 was inversely correlated with the expression of miR-455-3p. Loss-of-function of TPT1 had a similar effect on CRC cell proliferation in vitro as gain-of-function of miR-455-3p. Taken together, these data suggest that miR-455-3p functions as tumor suppressive RNA by targeting TPT1 in CRC, and it might be a potential therapeutic target for CRC patients.,IJCEP Copyright © 2018.