Biomed Pharmacother. 2015;75:111C16. studied. Here we demonstrated the role of miR-548m in modulating EMT in the breast cancer cell lines MDA-MB-231 and MCF-7. Expression data for primary breast cancer obtained from NCBI GEO data sets showed that miR-548m expression was downregulated in breast cancer patients compared with healthy group. We hypothesize that miR-548m acts as a tumor suppressor in breast cancer. Overexpression of miR-548m in both cell lines increased E-cadherin expression and decreased the EMT-associated transcription factors SNAI1, SNAI2, ZEB1, and ZEB2, as well as MMP9 expression. Consequently, migration and invasion capabilities of both MDA-MB-231 and MCF-7 cells were significantly inhibited in miR-548m-overexpressing cells. Analysis of 1 1,059 putative target genes of miR-548m revealed common pathways involving both tight junction and the mTOR signaling pathway, which has potential impacts on cell migration and invasion. Furthermore, this study identified aryl hydrocarbon receptor (AHR) as a direct target of miR-548m in breast cancer cells. Taken together, our findings suggest a novel function of miR-548m in reversing MLS0315771 the EMT of breast cancer by reducing their migratory and invasive potentials, at least in part via targeting AHR expression. values (adj. luciferase (Rgene under the control of the PGK promoter, and Rgene under the control of an SV40 promoter (as a transfection control) within the activities. Statistical Analysis Each experiment was performed three times at least. The results were expressed as the mean??standard error of the mean (SEM). Differences between values were statistically analyzed using Students luciferase activity. GAPDH was used as an internal control, respectively, to normalize the results. Graphs are displayed as mean??SEM, family of transcription factors. Expression of SNAI1, but not SNAI2, was downregulated in MDA-MB-231 following overexpression with miR-548m. By contrast, in MCF-7 cells, the expression of SNAI2 but not SNAI1 was downregulated. This disparity could be attributed to intrinsic regulatory network modulating SNAI1 and SNAI2, despite both being E-cadherin repressors. This is especially the case of the miR-548m/AHR axis, since activation of AHR has been shown to induce the transcriptional activation of its direct target, SNAI243. In addition, protein expression analysis could be done to detect proteins of EMT markers in breast cancer cells. EMT is also largely discussed as a promoter of metastasis, enabling motility and invasion of epithelial cells in cancer progression. In this study, miR-548m significantly reduces migration and invasion of breast cancer cells with no effect on cell proliferation. However, there have been a limited number of researches that directly address the biological role of miR-548m specifically. Lwin et al. showed the biological function of miR-548m in lymphoma progression, where miR-548m was found acting as a tumor suppressor by directly targeting HDAC6 and formed a feed-forward loop with c-Myc, MLS0315771 which later contributed to stroma-mediated c-Myc activation and miR-548m downregulation in a lymphoma microenvironment44. HDAC6 is related to several cell functions, including tubulin stabilization, cell motility, and cell cycle progression45. Interestingly, recent studies have shown that miR-548 family members are generally involved in regulating cell proliferation, apoptosis, migration, and invasion, where they act as tumor suppressor miRNA20,22,46 or oncogenic miRNA21,47 in different types of cancers. These suggested that miR-548 MLS0315771 family members might take on different functions in different types of cancers. The differential effects could have been contributed by the ability of a particular miRNA to target multiple mRNAs, thus consequently different MLS0315771 pathways and functions in tumorigenesis48C51. Indeed, in a screening for EMT modulators in bladder cancer, miR-548m was identified as an inducer Rabbit polyclonal to PELI1 of mesenchymal phenotype52. This is in contrast with other conserved miRNA families, such as let-7, that have an exact seed sequence that leads to similar targets, functions, and molecular mechanisms53. Taken together, these results indicate that the inhibitory effect of miR-548m.