miR-339-3p inhibits proliferation and metastasis of colorectal cancer

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.