The migratory capacity was evaluated as the total number of cells on the lower surface of the membrane, as determined by microscopy. Western blot analysis The cells in each well, including dead cells floating in the medium, were harvested and lysed in RIPA buffer. The protein concentrations of the lysates were determined using a bicinchoninic acid protein assay kit (Pierce Biotech). An aliquot of the lysate containing 50 μg proteins was subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis and then transferred to polyvinylidene fluoride membranes.
The membranes were blocked with blocking JAK inhibitor buffer (TBST containing 5% non-fat milk) for 1 h at room temperature and then incubated overnight at 4 °C with the following specific primary
antibodies: BIRC5, LASP1 β-actin (Cell Signaling Technology). Belinostat Subsequent incubation with the appropriate horseradish peroxidase-conjugated Semaxanib secondary antibodies was performed for 2 h at room temperature. Signals were detected using enhanced chemiluminescence reagents (Thermo). Luciferase reporter assay To evaluate the function of miR-203, the 3’-UTRs of BIRC5 and LASP1 with a miR-203 targeting sequence were cloned into the pMIR-REPORT luciferase reporter vector (Ambion). The sequences used to amplify BIRC5 3’-UTR were 5’-AAAGCCGGCCTGAAGTCTGGCGTAAGATG-3’ (forward) and 5’-GGACTAGTCCACATGAGACTTTATTG-3’ (reverse). The sequences used to amplify LASP1 3’-UTR were 5’-AAAGCCGGCGTCTTCTCTACAGTTCAC -3’ (forward) and 5’-GGACTAGTCCAGGAGAAAGATTCACTTG-3’
(reverse). Mutant BIRC5 and LASP1 3’-UTRs bearing a substitution of three nucleotides (TTT to CCC) in the miR-203 target sequence were generated using a Site-Directed Mutagenesis Kit (Agilent Technologies). Cells were co-transfected with luciferase reporter plasmids and miR-203 precursor (or control miRNA) along with Renilla Luciferase phRG-TK (Promega) as an internal control using Lipofectamine 2000 (Invitrogen). Luciferase activity was measured 72 h after transfection using the Dual-Luciferase Prostatic acid phosphatase Reporter Assay System (Promega). All experiments were performed in triplicate. Statistical analysis Statistical analysis was performed using one-way ANOVA or Student’s t test. Values of P < 0.05 were considered significant. Data were represented as the mean ± S.D. GraphPad Prism 5.0 software was used for all data analysis. Results miR-203 expression was decreased in TNBC cell lines while BIRC5 and LASP1 expression was increased We detected the abundance of miR-203 in triple-negative human breast cancer cell lines: MDA-MB-468 and MDA-MB-231 and a normal breast cell line: MCF-10A, by real-time PCR. TNBC cell lines (MDA-MB-468 and MDA-MB-231) showed significant miR-203 repression than normal breast cell line MCF-10A. We also detected BIRC5 and LASP1 expression at mRNA level in breast cancer cell lines and MCF-10A cell line.