title: MicroRNA miR-590-5p inhibits breast cancer cell stemness and metastasis by targeting SOX2.
abstract: SOX2 (Sry-related high-mobility box SOX-2) is a transcription factor, which is essential for maintaining the cancer cell stemness. However, the role of microRNAs targeting  SOX2 in cancer cell stemness remains unclear. We examined the effect of miR-590-5p, which targeted  SOX2, on the breast cancer cell stemness and metastasis.
  
  
  
  We predicted and screened microRNA targeting SOX2, and further investigated the regulatory role of miR-590-5p on the level of SOX2 with Western blot, luciferase reporting assay and qRT-PCR analysis. Flow cytometry was performed to detect the effect of miR-590-5p on the breast cancer stem cell population with ALDEFLUOR Assay. We inoculated the breast cancer cells transfected with or without miR-590-5p to NOD/SCID mice to detect the tumorigenicity in vivo. Finally, forty-nine pairs of breast cancer samples and adjacent noncancerous tissues were obtained, and immunohistochemistry (IHC) with SOX2 antibody and qRT-PCR assay were used to quantify the expression of miR-590-5p in breast cancer samples.
  
  
  
  miR-590-5p significantly downregulated the SOX2 protein expression, and inhibition of miR-590-5p increased SOX2 expression. The luciferase reporter assay indicated that miR-590-5p decreased the SOX2 3'UTR (3' untranslated region) reporter activity but not the luciferase activity of the mutant reporter, in which the binding sites for miR-590-5p were mutated. ALDEFLUOR Assay showed that miR-590-5p significantly decreased breast cancer stem cells population. NOD/SCID nude mice experiments indicated that miR-590-5p significantly inhibited tumorigenicity of breast cancer cells. IHC assay and qRT-PCR suggested that miR-590-5p expression was downregulated in breast cancer patients, and negatively correlated with SOX2.
  
  
  
  miR-590-5p inhibited breast cancer cell stemness through targeting SOX2. Our study indicated that miR-590-5p might be a useful strategy for breast cancer treatment.
authors.affiliation: Department of Medical Oncology, Capital Medical University Cancer Center, Beijing Shijitan Hospital, Beijing, P.R. China. jun.ren@duke.edu.
authors.forename: L
authors.initials: L
authors.lastname: Zhou
authors.forename: L-C
authors.initials: LC
authors.lastname: Zhao
authors.forename: N
authors.initials: N
authors.lastname: Jiang
authors.forename: X-L
authors.initials: XL
authors.lastname: Wang
authors.forename: X-N
authors.initials: XN
authors.lastname: Zhou
authors.forename: X-L
authors.initials: XL
authors.lastname: Luo
authors.forename: J
authors.initials: J
authors.lastname: Ren
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D008819:Mice, Nude; D016513:Mice, SCID; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D014411:Neoplastic Stem Cells / Q000473:pathology*; D055748:SOXB1 Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C568221:MIRN590 microRNA, human; D035683:MicroRNAs; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors