Objective: The aim of this study was to evaluate the mechanisms involved with miRNA-708 and its targeting of bone morphogenetic protein and activin membrane-bound inhibitor in cell proliferation, migration, and apoptosis in mice with melanoma via the Wnt and transforming growth factor β signaling pathways.
Methods: Sixty mice were recruited of which 40 were subsequently assigned into the experimental group (22 mice were successfully established as melanoma model and 18 mice used in tumor xenograft), and the normal control group consisted of 20 mice. B16 cells were assigned to the normal, blank, and negative control, miR-708 mimics, miR-708 inhibitors, si-BAMBI, and miR-708 inhibitors + si-bone morphogenetic protein and activin membrane-bound inhibitor groups. Western blotting and reverse transcription quantitative polymerase chain reaction were employed to detect the expression levels within the tissues and cell lines. TCF luciferase reporter (TOP-FLASH) or a control vector (FOP-FLASH) was applied to detect the activity of the Wnt signaling pathway. MTT3-(4,5-Dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide assay, flow cytometry, scratch test, and Transwell assay were conducted, respectively, for cell proliferation, apoptosis, migration, and invasion, while tumor xenograft procedures were performed on the nude mice recruited for the study.
Results: Compared to the normal control group, the model group displayed increased expressions of bone morphogenetic protein and activin membrane-bound inhibitor, Wnt10B, P53, and Bcl-2; TOPflash activity; β-catenin expression; cell proliferation; migration; and invasion capabilities while decreased expressions of miR-708, vascular endothelial growth factor, Fas, Bax, Caspase-3, and cleaved Caspase-3 and apoptosis rate. Compared to the blank and negative control groups, the miR-708 mimics and small-interfering RNA-bone morphogenetic protein and activin membrane-bound inhibitor groups exhibited decreases expressions of bone morphogenetic protein and activin membrane-bound inhibitor, Wnt10B, P53, and Bcl-2 and decreased proliferation, migration, and invasion capabilities, while increases in the apoptosis rate, expressions of vascular endothelial growth factor, Fas, Bax, Caspase-3, and cleaved Caspase-3; however, downregulated levels of TOPflash activity and β-catenin expression were recorded. The miR-708 inhibitors group displayed an opposite trend.
Conclusion: Downregulation of miR-708-targeted bone morphogenetic protein and activin membrane-bound inhibitor inhibits the proliferation and migration of melanoma cells through the activation of the transforming growth factor β pathway and the suppression of Wnt pathway.
Keywords: BAMBI gene; TGF-β signaling pathway; Wnt signaling pathway; apoptosis; melanoma; miRNA-708; migration; proliferation.