Effects And Mechanism Of MicroRNA-346 On Prostate Cancer Cell Migration And Invasion

Objective: The objective of this study was to investigate the effect of miR-346 on migration and invasion ability of prostate cancer DU145 and PC-3 cells, and to investigate whether miR-346 have any effects on epithelial-mesenchymal transition(EMT) of prostate cancer and if any, the mechanism.Methods: Synthesized mimics or inhibitors of miR-346 were transfected into human CRPC cell lines DU145 and PC-3 using Lipofectamine-2000. Change of the migration and invasion ability of the PCa cells were evaluated using Transwell migration/invasion assays and wound-healing assay. Meanwhile the expression of SMAD3 and SMAD4, which are key moleculars in the TGFβ/smad signaling pathway, as well as the EMT markers including E-cadherin and N-cadherin were evaluated using qPCR and Western blot assay.Results: Wound-healing assay and Transwell migration assay showed that PCa cell mobility were significantly promoted upon transfection of miR-346 mimics and inhibited upon transfection of miR-346 inhibitors. Transwell invasion assays showed the similar results as that in the migration assays. QPCR and Western Blot showed that mRNA and protein expression of SMAD3 and SMAD4 were decreased when transfected with miR-346 mimics, or vice versa, increased in the miR-346 inhibitor group. Further research in DU145 cells showed that the protein expression of E-cadherin was decreased and N-cadherin increased when miR-346 was added in. Accordingly, when we used the miR-346 inhibitor, we got opposite results as were expected.Conclusions: The abilities of migration and invasion of both DU145 and PC-3 cells were closely-related to the expression level of miR-346; the protein level of epithelial marker E-cadherin was negative correlation with the expression of miR-346, wheile the protein level of mesenchymal marker N-cadherin was positive correlation with the expression of miR-346. MiR-346 may promote EMT to promote PCa metastasis. MiR-346 inhibits the expression of both SMAD3 and SMAD4, and consequently, maybe by regulating the TGFβ signal-pathway, affects the progression of PCa.