Fig. 5

miR-135b-5p negatively regulated expression of AGR2 and increased doxorubicin-sensitivity of MCF-7 cells in vitro. a MCF-7 cells were transfected with mimics of a control miRNA, miR-135b-5p or miR-194-5p. Twenty-four hours after transfection, level of AGR2 mRNA was measured by qPCR (n = 3). b AGR2 3′-UTR (1097 bp) and a mutant AGR2 3′-UTR (1090 bp) fragments were synthesized and cloned to pmirGLO Dual-Luciferase miRNA Target Expression Vector. Luciferase vector and miR-135b-5p mimic were co-transfected into MCF-7 cells. Twenty-four hours after transfection, firefly and renilla luciferase activities of cell lysate were analyzed. Luciferase activity was expressed as ratio of Firefly/Renilla. c MCF-7 cells were transfected with mimics of a control miRNA or miR-135b-5p, followed by treatment with doxorubicin (100 nM) for 48 h. AGR2-expression was detected using western blot. d-e MCF-7 cells were stably transduced with lentivirual vector expressing double strand precursors of a control miRNA or miR-135b. d AGR2-expression was detected using western blot. e Cell viability was measured by CCK-8 assay (n = 6). f Cells were treated with doxorubicin for 48 h followed by measuring for cell viability (n = 6). Experiment was repeated three times. Expression levels of mRNA represent fold changes. Data are shown as mean ± SD and are compared using unpaired t test or one-way ANOVA test. *, p < 0.05; n.s., no significance