The online version of this article (https://doi.org/10.1186/s12943-017-0754-0) contains supplementary material, which is available to authorized users.
Triple-negative breast cancer (TNBC) is highly invasive and aggressive and lacks specific molecular targets to improve the prognosis. MiR-25-3p promotes proliferation of many tumors and its role and underlying mechanisms in TNBC remain to be well elucidated.
Differential expression of miR-25-3p in TNBC was measured with quantitative real-time PCR (qRT-PCR) in both TNBC tissues and cell lines and was validated in the Cancer Genome Atlas (TCGA) database. The effects of miR-25-3p on proliferation, apoptosis capacity of TNBC were evaluated using Cell counting kit-8 (CCK-8), colony formation assay and Annexin V-FITC/PI analyses. The tumor growth in vivo was observed in xenograft model. Luciferase reporter assay, qPCR and western blot were performed to validate a potential target of miR-25-3p in TNBC. Involvement of the AKT and MAPK pathways was investigated by western blot.
MiR-25-3p was found to be upregulated in TNBC in tissues and cell lines. MiR-25-3p promoted TNBC cell proliferation in vitro and tumor growth in xenograft model, while suppression of miR-25-3p induced cell apoptosis. The luciferase reporter assay confirmed that B-cell translocation gene 2 (BTG2) might be a direct target of miR-25-3p, and its expression was negatively regulated by miR-25-3p. Moreover, inhibition of BTG2 expression accounted for the role of miR-25-3p in TNBC. Furthermore, BTG2 suppression might indirectly activate the AKT and ERK-MAPK signaling pathways to mediate the downstream effects of miR-25-3p.
This study demonstrates that miR-25-3p promotes proliferation by targeting tumor suppressor BTG2 and may identify new diagnostic and therapeutic targets in TNBC.
Additional file 1: Table S1. Nine differentially expressed miRNAs from miRNA microarray assay in TNBC and adjacent normal tissues. (DOCX 126 kb)12943_2017_754_MOESM1_ESM.docx
Additional file 2: FigureS1. a. qRT-PCR was used to verify the expression of miR-25-3p in MDA-MB-231 and Sum-1315 cells transfected with mimics b. Cell proliferation was determined by CCK-8 assays in MDA-MB-231, Sum-1315 cells transfected with miR-25-3p mimics. c. The colony formation results of cells transfected with mimics lentivirus. *p < 0.05, **p < 0.01. The data expressed as the mean ± SD. (TIFF 1901 kb)12943_2017_754_MOESM2_ESM.tif
Additional file 3: Figure S2. a. Edu cell growth in MDA-MB-231, Sum-1315 after transfection with miR-25-3p-mimics compared with the control. b. Flow cytometry analysis of the effect of miR-25-3p expression alteration on cell apoptosis and apoptotic marker expression. *p < 0.05, **p < 0.01. The data expressed as the mean ± SD. (TIFF 3545 kb)12943_2017_754_MOESM3_ESM.tif
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- MiR-25-3p promotes the proliferation of triple negative breast cancer by targeting BTG2
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