RESUMO
Yin Yang 1 (YY1) is highly expressed in various types of cancers and regulates tumorigenesis through multiple pathways. In the present study, we evaluated YY1 expression levels in breast cancer cell lines, a breast cancer TMA, and two gene arrays. We observed that, compared with normal samples, YY1 is generally overexpressed in breast cancer cells and tissues. In functional studies, depletion of YY1 inhibited the clonogenicity, migration, invasion, and tumor formation of breast cancer cells, but did not affect the clonogenicity of nontumorigenic cells. Conversely, ectopically expressed YY1 enhanced the migration and invasion of nontumorigenic MCF-10A breast cells. In both a monolayer culture condition and a three-dimensional Matrigel system, silenced YY1 expression changed the architecture of breast cancer MCF-7 cells to that resembling MCF-10A cells, whereas ectopically expressed YY1 in MCF-10A cells had the opposite effect. Furthermore, we detected an inverse correlation between YY1 and p27 expression in both breast cancer cells and xenograft tumors with manipulated YY1 expression. Counteracting the changes in p27 expression attenuated the effects of YY1 alterations on these cells. In addition, YY1 promoted p27 ubiquitination and physically interacted with p27. In conclusion, our data suggest that YY1 is an oncogene and identify p27 as a new target of YY1.
Assuntos
Neoplasias da Mama/metabolismo , Antígeno Nuclear de Célula em Proliferação/metabolismo , Fator de Transcrição YY1/fisiologia , Animais , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Ciclo Celular/fisiologia , Movimento Celular/fisiologia , Proliferação de Células , Forma Celular/fisiologia , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica/fisiologia , Técnicas de Silenciamento de Genes , Humanos , Camundongos , Camundongos Nus , Invasividade Neoplásica , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Proteínas de Neoplasias/fisiologia , Transplante de Neoplasias , Células-Tronco Neoplásicas/patologia , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Antígeno Nuclear de Célula em Proliferação/genética , Processamento de Proteína Pós-Traducional/fisiologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Transplante Heterólogo , Células Tumorais Cultivadas , Regulação para Cima/fisiologia , Fator de Transcrição YY1/genética , Fator de Transcrição YY1/metabolismoRESUMO
Yin Yang 1 (YY1) is a multifunctional protein with regulatory potential in tumorigenesis. Ample studies demonstrated the activities of YY1 in regulating gene expression and mediating differential protein modifications. However, the mechanisms underlying YY1 gene expression are relatively understudied. G-quadruplexes (G4s) are four-stranded structures or motifs formed by guanine-rich DNA or RNA domains. The presence of G4 structures in a gene promoter or the 5'-UTR of its mRNA can markedly affect its expression. In this report, we provide strong evidence showing the presence of G4 structures in the promoter and the 5'-UTR of YY1. In reporter assays, mutations in these G4 structure forming sequences increased the expression of Gaussia luciferase (Gluc) downstream of either YY1 promoter or 5'-UTR. We also discovered that G4 Resolvase 1 (G4R1) enhanced the Gluc expression mediated by the YY1 promoter, but not the YY1 5'-UTR. Consistently, G4R1 binds the G4 motif of the YY1 promoter in vitro and ectopically expressed G4R1 increased endogenous YY1 levels. In addition, the analysis of a gene array data consisting of the breast cancer samples of 258 patients also indicates a significant, positive correlation between G4R1 and YY1 expression.
Assuntos
Regiões 5' não Traduzidas , RNA Helicases DEAD-box/metabolismo , Quadruplex G , Regiões Promotoras Genéticas , Recombinases/metabolismo , Fator de Transcrição YY1/genética , Sequência de Bases , Neoplasias da Mama/enzimologia , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Cátions Monovalentes/química , Linhagem Celular , Dicroísmo Circular , DNA/química , Pegada de DNA , Feminino , Sequência Rica em GC , Expressão Gênica , Genes Reporter , Humanos , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos/química , RNA/química , Fator de Transcrição YY1/metabolismoRESUMO
As a transcription factor, Yin Yang 1 (YY1) regulates the transcription of a dazzling list of genes and the number of its targets still mounts. Recent studies revealed that YY1 possesses functions independent of its DNA binding activity and its regulatory role in tumorigenesis has started to emerge.