title: MicroRNA-200 family modulation in distinct breast cancer phenotypes.
abstract: The epithelial to mesenchymal transition (EMT) contributes to tumor invasion and metastasis in a variety of cancer types. In human breast cancer, gene expression studies have determined that basal-B/claudin-low and metaplastic cancers exhibit EMT-related characteristics, but the molecular mechanisms underlying this observation are unknown. As the family of miR-200 microRNAs has been shown to regulate EMT in normal tissues and cancer, here we evaluated whether the expression of the miR-200 family (miR-200f) and their epigenetic state correlate with EMT features in human breast carcinomas. We analyzed by qRT-PCR the expression of miR-200f members and various EMT-transcriptional inducers in a series of 70 breast cancers comprising an array of phenotypic subtypes: estrogen receptor positive (ER+), HER2 positive (HER2+), and triple negative (TN), including a subset of metaplastic breast carcinomas (MBCs) with sarcomatous (homologous or heterologous) differentiation. No MBCs with squamous differentiation were included. The DNA methylation status of miR-200f loci in tumor samples were inspected using Sequenom MassArray® MALDI-TOF platform. We also used two non-tumorigenic breast basal cell lines that spontaneously undergo EMT to study the modulation of miR-200f expression during EMT in vitro. We demonstrate that miR-200f is strongly decreased in MBCs compared with other cancer types. TN and HER2+ breast cancers also exhibited lower miR-200f expression than ER+ tumors. Significantly, the decreased miR-200f expression found in MBCs is accompanied by an increase in the expression levels of EMT-transcriptional inducers, and hypermethylation of the miR-200c-141 locus. Similar to tumor samples, we demonstrated that downregulation of miR-200f and hypermethylation of the miR-200c-141 locus, together with upregulation of EMT-transcriptional inducers also occur in an in vitro cellular model of spontaneous EMT. Thus, the expression and methylation status of miR-200f could be used as hypothetical biomarkers to assess the occurrence of EMT in breast cancer.
authors.affiliation: Department of Pathology, Instituto de Biomedicina de Sevilla-CSIC-Universidad de Sevilla, Hospital Universitario Virgen del Rocío, Seville, Spain.
authors.forename: María Ángeles
authors.initials: MÁ
authors.lastname: Castilla
authors.forename: Juan
authors.initials: J
authors.lastname: Díaz-Martín
authors.forename: David
authors.initials: D
authors.lastname: Sarrió
authors.forename: Laura
authors.initials: L
authors.lastname: Romero-Pérez
authors.forename: María Ángeles
authors.initials: MÁ
authors.lastname: López-García
authors.forename: Begoña
authors.initials: B
authors.lastname: Vieites
authors.forename: Michele
authors.initials: M
authors.lastname: Biscuola
authors.forename: Susana
authors.initials: S
authors.lastname: Ramiro-Fuentes
authors.forename: Clare M
authors.initials: CM
authors.lastname: Isacke
authors.forename: José
authors.initials: J
authors.lastname: Palacios
mesh_terms: D001940:Breast / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D004247:DNA / Q000235:genetics; D019175:DNA Methylation; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D010641:Phenotype; D011401:Promoter Regions, Genetic
chemical_list: C533896:MIRN200 microRNA, human; D035683:MicroRNAs; D004247:DNA