Abstract
MicroRNAs (miRNAs) serve important roles in regulating cancer cell proliferation and metastasis. The same hairpin RNA structure may produce mature products from each strand, termed miR-5p and miR-3p, which can bind different mRNAs. Previously, the present authors reported that miR-339-5p could inhibit cell proliferation and migration by targeting the 3'-untranslated region (3'-UTR) of PRL-1 mRNA. The present study analyzed the expression, function and preliminary regulatory mechanism of miR-339-3p in colorectal cancer (CRC). The results of reverse transcription-quantitative polymerase chain reaction analysis demonstrated that miR-339-3p is downregulated in CRC specimens and highly invasive cell lines. Furthermore, the low-level expression of miR-339-3p was significantly associated with lymph node metastasis in patients with CRC; however, reduced miR-339-3p expression was not associated with age, gender or the differentiation status of the tumor. Overexpression of miR-339-3p was sufficient to suppress tumor growth and metastasis in vitro. In addition, the present study demonstrated that unlike miR-339-5p, PRL-1 expression was not regulated by miR-339-3p. The findings of the present study indicate that miR-339-5p and miR-339-3p may target different mRNA. The target gene of miR-339-3p requires future identification.