title: Triple-negative and luminal A breast tumors: differential expression of miR-18a-5p, miR-17-5p, and miR-20a-5p.
abstract: New concepts in epigenetics, microRNAs, and gene expression analysis have significantly enhanced knowledge of cancer pathogenesis over the last decade. MicroRNAs (miRNAs) are a class of non-coding RNAs that regulate gene expression by base pairing with target messenger RNAs (mRNAs), resulting in the repression of translation or the degradation of mRNA. To compare the carcinogenic process in tumors with different prognoses, we used real-time RT-PCR to evaluate the miRNA expression profiles of 24 triple-negative breast invasive ductal carcinoma, 20 luminal A breast invasive ductal carcinoma, and 13 normal breast parenchyma controls. We extracted total RNA from tissues fixed in formol and embedded in paraffin (FFPE). Results revealed the upregulation of miR-96-5p (9.35-fold; p = 0.000115), miR-182-5p (7.75-fold; p = 0.000033), miR-7-5p (6.71-fold; p = 0.015626), and miR-21-5p (6.10-fold; p = 0.000000) in tumors group. In addition, the expression of miR-125b-5p (4.49-fold; p = 0.000000) and miR-205-5p (4.36-fold; p = 0.006098) was downregulated. When the expression profiles of triple-negative and luminal A tumors were compared, there was enhanced expression of miR-17-5p (4.27-fold; p = 0.000664), miR-18a-5p (9.68-fold; p = 0.000545), and miR-20a-5 (4.07-fold; p = 0.001487) in the triple-negative tumors compared with luminal A. These data suggest that there is a similar regulation of certain miRNAs in triple-negative and luminal A tumors. However, it is possible that differences in the expression of miR-17-92 cluster will explain the phenotypic differences between these molecular tumor subtypes.
authors.affiliation: Laboratório de Ginecologia Molecular e Estrutural-LIM 58, Disciplina de Ginecologia, Faculdade de Medicina, Universidade de São Paulo, Rua Dr Arnaldo, 255, Sala 2031, São Paulo-SP, Brazil.
authors.forename: Carlos Marino Cabral
authors.initials: CM
authors.lastname: Calvano Filho
authors.forename: Daniele Carvalho
authors.initials: DC
authors.lastname: Calvano-Mendes
authors.forename: Kátia Cândido
authors.initials: KC
authors.lastname: Carvalho
authors.forename: Gustavo Arantes
authors.initials: GA
authors.lastname: Maciel
authors.forename: Marcos Desidério
authors.initials: MD
authors.lastname: Ricci
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Torres
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Filassi
authors.forename: Edmund Chada
authors.initials: EC
authors.lastname: Baracat
mesh_terms: D001940:Breast / Q000378:metabolism; D018270:Carcinoma, Ductal, Breast / Q000235:genetics; D005260:Female; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000032:analysis*; D064726:Triple Negative Breast Neoplasms / Q000235:genetics*
chemical_list: D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D035683:MicroRNAs; C085126:FOXO1 protein, human; C524941:MIRN17 microRNA, human; C581632:MIRN18 microRNA, human; C534425:MIR205, human; C534451:MIRN20a microRNA, human