RESUMO
TP53 is the most frequently mutated gene in human cancers. Most TP53 genomic alterations are missense mutations, which cause a loss of its tumour suppressor functions while providing mutant p53 (mut_p53) with oncogenic features (gain-of-function). Loss of p53 tumour suppressor functions alters the transcription of both protein-coding and non-protein-coding genes. Gain-of-function of mut_p53 triggers modification in gene expression as well; however, the impact of mut_p53 on the transcription of the non-protein-coding genes and whether these non-protein-coding genes affect oncogenic properties of cancer cell lines are not fully explored. In this study, we suggested that LINC01605 (also known as lincDUSP) is a long non-coding RNA regulated by mut_p53 and proved that mut_p53 directly regulates LINC01605 by binding to an enhancer region downstream of the LINC01605 locus. We also showed that the loss or downregulation of LINC01605 impairs cell migration in a breast cancer cell line. Eventually, by performing a combined analysis of RNA-seq data generated in mut_TP53-silenced and LINC01605 knockout cells, we showed that LINC01605 and mut_p53 share common gene pathways. Overall, our findings underline the importance of ncRNAs in the mut_p53 network in breast and ovarian cancer cell lines and in particular the importance of LINC01605 in mut_p53 pro-migratory pathways.
Assuntos
Neoplasias Ovarianas , RNA Longo não Codificante , Proteína Supressora de Tumor p53 , Feminino , Humanos , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Mutação de Sentido Incorreto , Neoplasias Ovarianas/genética , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , RNA Longo não Codificante/genéticaRESUMO
Loss of expression of miR-200 family members has been implicated in cellular plasticity, a phenomenon that accounts for epithelial-to-mesenchymal transition (EMT) and stem-like features of many carcinomas and is considered a major cause of tumor aggressiveness and drug resistance. Nevertheless, the mechanisms of miR-200 downregulation in breast cancer are still largely unknown. Here we show that miR-200c expression inversely correlates with miR-200c/miR-141 locus methylation in triple-negative breast tumors (TNBC). Importantly, low levels of miR-200c expression and high levels of miR-200c/miR-141 locus methylation associated with lymph node metastasis. Moreover, miR-200c/miR-141 locus methylation was significantly related to high expression of ZEB1 in two independent TNBC series. Silencing of ZEB1 in vitro reduced miR-200c/miR-141 DNA methylation and, concurrently, decreased histone H3K9 trimethylation. This chromatin modifications were paralleled by an increase in the expression of both miR-200c and E-cadherin. Similar effects were achieved by treatment with a demethylating agent. Our data suggest that gene methylation is an important element in the regulation of the miR-200c/ZEB1 axis and that chromatin remodeling of the miR-200c/miR-141 locus is affected by ZEB1 and, thus, contributes to ZEB1-induced cellular plasticity. © 2016 Wiley Periodicals, Inc.
Assuntos
Biomarcadores Tumorais/genética , Epigênese Genética/genética , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , MicroRNAs/genética , Neoplasias de Mama Triplo Negativas/genética , Homeobox 1 de Ligação a E-box em Dedo de Zinco/metabolismo , Apoptose , Western Blotting , Movimento Celular , Proliferação de Células , Terapia Combinada , Metilação de DNA , Transição Epitelial-Mesenquimal , Feminino , Seguimentos , Humanos , Técnicas Imunoenzimáticas , Metástase Linfática , Pessoa de Meia-Idade , Gradação de Tumores , Invasividade Neoplásica , Estadiamento de Neoplasias , Prognóstico , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Estudos Retrospectivos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Taxa de Sobrevida , Neoplasias de Mama Triplo Negativas/patologia , Neoplasias de Mama Triplo Negativas/terapia , Células Tumorais Cultivadas , Homeobox 1 de Ligação a E-box em Dedo de Zinco/genéticaRESUMO
Increasing evidence indicates that invasive properties of breast cancers rely on gain of mesenchymal and stem features, which has suggested that the dual targeting of these phenotypes may represent an appealing therapeutic strategy. It is known that the fraction of stem cells can be enriched by culturing breast cancer cells as mammospheres (MS), but whether these pro-stem conditions favor also the expansion of cells provided of mesenchymal features is still undefined. In the attempt to shed light on this issue, we compared the phenotypes of a panel of 10 breast cancer cell lines representative of distinct subtypes (luminal, HER2-positive, basal-like and claudin-low), grown in adherent conditions and as mammospheres. Under MS-proficient conditions, the increment in the fraction of stem-like cells was associated to upregulation of the mesenchymal marker Vimentin and downregulation of the epithelial markers expressed by luminal cells (E-cadherin, KRT18, KRT19, ESR1). Luminal cells tended also to upregulate the myoepithelial marker CD10. Taken together, our data indicate that MS-proficient conditions do favor mesenchymal/myoepithelial features, and indicate that the use of mammospheres as an in vitro tumor model may efficiently allow the exploitation of therapeutic approaches aimed at targeting aggressive tumors that have undergone epithelial-to-mesenchymal transition
