MicroRNA-200 Family Modulation in Distinct Breast Cancer Phenotypes

• Published in: PloS one Vol. 7; no. 10; p. e47709
• Main Authors: Castilla, María Ángeles, Díaz-Martín, Juan, Sarrió, David, Romero-Pérez, Laura, López-García, María Ángeles, Vieites, Begoña, Biscuola, Michele, Ramiro-Fuentes, Susana, Isacke, Clare M., Palacios, José
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 24.10.2012; Public Library of Science (PLoS)
• Subjects: Biology; Biomarkers; Breast - metabolism; Breast - pathology; Breast cancer; Breast carcinoma; Breast Neoplasms - genetics; Breast Neoplasms - pathology; Cancer; Cancer genetics; Cell Line, Tumor; Deoxyribonucleic acid; Differentiation; DNA; DNA - genetics; DNA Methylation; Epigenetic inheritance; Epigenetics; Epithelial-Mesenchymal Transition; ErbB-2 protein; Estrogen receptors; Estrogens; Female; Gene expression; Gene Expression Regulation, Neoplastic; Genes; Genetic aspects; Genotype & phenotype; Homology; Humans; Loci; Medical research; Medicine; Mesenchyme; Metastases; Metastasis; Methylation; MicroRNA; MicroRNAs; MicroRNAs - genetics; miRNA; Modulation; Molecular modelling; Pathology; Phenotype; Promoter Regions, Genetic; Ribonucleic acid; RNA; Stem cells; Tissues; Transcription; Transcription factors; Tumorigenesis; Tumors; Spain
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0047709

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.