407018

MIR27A

microRNA 27a;MIR27A;microRNA 27a

hsa-mir-27a

19p13.13

ncRNA

MicroRNAs (miRNAs) have been shown to function as key regulators of tumor progression and metastasis. Recent studies have indicated that the miRNAs comprising the miR-23b/27b/24 cluster might influence tumor metastasis, although the precise nature of this regulation remains unclear. Here, expression of the miR-23b/27b/24 cluster is found to correlate with metastatic potential in mouse and human breast cancer cell lines and is elevated in metastatic lung lesions in human breast cancer patients. Ectopic expression of the miRNAs in the weakly metastatic mouse 4TO7 mammary tumor cell line had no effect on proliferation or morphology of tumor cells in vitro but was found to increase lung metastasis in a mouse model of breast cancer metastasis. Furthermore, gene expression profiling analysis of miRNA overexpressing 4TO7 cells revealed the direct targeting of prosaposin (PSAP), which encodes a secreted protein found to be inversely correlated with metastatic progression in human breast cancer patients. Importantly, ectopic expression of PSAP was able to suppress the metastatic phenotype in highly metastatic 4T1 and MDA-MB-231 SCP28 cells, as well as in cells ectopically expressing miR-23b/27b/24. These findings support a metastasis-promoting function of the miR-23b/27b/24 cluster of miRNAs, which functions in part through the direct inhibition of PSAP.

microRNAs (miRNAs) play an important role in tumorigenesis. However, the mechanisms by which miRNAs regulate gastric cancer metastasis remain poorly understood. In the current study, we defined the target genes and biological functions of miR-27 with a luciferase reporter assay and Western blot analysis. We verified that miR-27 levels were increased in gastric cancer tissues. The overexpression of miR-27 promoted the metastasis of AGS cells, whereas its depletion decreased cell metastasis. Up-regulation of miR-27 increased the levels of the epithelial-mesenchymal transition (EMT)-associated genes ZEB1, ZEB2, Slug, and Vimentin, as well as decreased E-cadherin levels. We demonstrated that miR-27 promoted EMT by activating the Wnt pathway. Finally, the APC gene was identified as the direct and functional target of miR-27. These results suggest an important role of miR-27 in regulating metastasis of gastric cancer and implicate the potential application of miR-27 in gastric cancer therapy.