Figure 1

miR-26 inhibits breast cancer cell growth. (a, b) Effect of 17β-estradiol (E2) on miR-26a and miR-26b expression. MCF-7 and T47D were treated with 10 nmol/l E2 in phenol red-free medium containing 5% charcoal-stripped fetal bovine serum and microRNAs (miRNAs) from a triplicate sample were isolated at indicated time points. The miRNA level was measured by TaqMan stem-loop quantitative real-time polymerase chain reaction (qRT-PCR). U6 was used as an internal control. Relative expression level of (a) miR-26a and (b) miR-26b. (c) MCF-7 cells after 2 days of E2 deprivation were transfected with NC, miR-26a or miR-26b mimics and 1 day later were seeded in six-well plates with or without 10 nmol/l E2. At the indicated time points after transfection, cells were trypsinized and total cell numbers were counted using Trypan blue. (d) MCF-7 cells after 2 days of E2 deprival were transfected with NC, miR-26a or miR-26b mimics and 1 day later were seeded in 96-well plates with or without 10 nmol/l E2. At 72 hours after plating, the MTT assay was performed to determine the proliferation (viability) of MCF-7 cells. (e) Sequences of mature miR-26a/b, and one repeat of sponge. (f, g) Relative expression levels of miR-26a and miR-26b between MCF-7-Vec, MCF-7-Sponge-miR-26 or T47D-Vec, T47D-Sponge-miR-26 were measured by TaqMan stem-loop qRT-PCR. (h) MCF-7-Vec and MCF-7-Sponge-miR-26 cells after 3 days of E2 deprivation were seeded in six-well plates with or without 10 nmol/l E2. At the indicated time points, MCF-7-Vec and MCF-7-Sponge-miR-26 cells were trypsinized and total cell numbers were counted using Trypan blue. (i) MCF-7-Vec and MCF-7-Sponge-miR-26 cells after 3 days of E2 deprivation were seeded in 96-well plates with or without 10 nmol/l E2. At 96 hours after plating, the MTT assay was performed to determine the proliferation of MCF-7-Vec and MCF-7-Sponge-miR-26 cells. *P < 0.05. **P < 0.01.