RT Journal Article T1 MicroRNA-200 family modulation in distinct breast cancer phenotypes. A1 Castilla, María Ángeles A1 Díaz-Martín, Juan A1 Sarrió, David A1 Romero-Pérez, Laura A1 López-García, María Ángeles A1 Vieites, Begoña A1 Biscuola, Michele A1 Ramiro-Fuentes, Susana A1 Isacke, Clare M A1 Palacios, José K1 Neoplasias de la Mama K1 Fenotipo K1 Transición Epitelial-Mesenquimal AB 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. PB Public Library of Science YR 2012 FD 2012-10-24 LK http://hdl.handle.net/10668/847 UL http://hdl.handle.net/10668/847 LA en NO Castilla MÁ, Díaz-Martín J, Sarrió D, Romero-Pérez L, López-García MÁ, Vieites B, et al. MicroRNA-200 family modulation in distinct breast cancer phenotypes. PLoS ONE; 7(10):e47709 NO Journal Article; Research Support, Non-U.S. Gov't; DS RISalud RD Apr 19, 2025