RESUMO
BHLHE40 and BHLHE41 (BHLHE40/41) are basic helix-loop-helix type transcription factors that play key roles in multiple cell behaviors. BHLHE40/41 were recently shown to be involved in an epithelial-to-mesenchymal transition (EMT). However, the precise mechanism of EMT control by BHLHE40/41 remains unclear. In the present study, we demonstrated that BHLHE40/41 expression was controlled in a pathological stage-dependent manner in human endometrial cancer (HEC). Our in vitro assays showed that BHLHE40/41 suppressed tumor cell invasion. BHLHE40/41 also suppressed the transcription of the EMT effectors SNAI1, SNAI2, and TWIST1. We identified the critical promoter regions of TWIST1 for its basal transcriptional activity. We elucidated that the transcription factor SP1 was involved in the basal transcriptional activity of TWIST1 and that BHLHE40/41 competed with SP1 for DNA binding to regulate gene transcription. This study is the first to report the detailed functions of BHLHE40 and BHLHE41 in the suppression of EMT effectors in vitro. Our results suggest that BHLHE40/41 suppress tumor cell invasion by inhibiting EMT in tumor cells. We propose that BHLHE40/41 are promising markers to predict the aggressiveness of each HEC case and that molecular targeting strategies involving BHLHE40/41 and SP1 may effectively regulate HEC progression.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Neoplasias do Endométrio/genética , Proteínas de Homeodomínio/genética , Proteínas Nucleares/genética , Fator de Transcrição Sp1/genética , Proteína 1 Relacionada a Twist/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/biossíntese , Sítios de Ligação/genética , Biomarcadores Tumorais/genética , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Progressão da Doença , Neoplasias do Endométrio/patologia , Transição Epitelial-Mesenquimal/genética , Feminino , Células HEK293 , Proteínas de Homeodomínio/biossíntese , Humanos , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Regiões Promotoras Genéticas/genética , Interferência de RNA , RNA Mensageiro/genética , RNA Interferente Pequeno , Fatores de Transcrição da Família Snail , Fatores de Transcrição/genética , Transcrição Gênica/genéticaRESUMO
Homeodomain-only protein/not expressed in choriocarcinoma clone 1 (HOP/NECC1) is a newly identified gene that modifies the expression of cardiac-specific genes and thereby regulates heart development. More recently, HOP/NECC1 was reported to be a suppressor of choriocarcinogenesis. Here, we examined the temporal expression profile of HOP/NECC1 in wild-type mouse placenta. We found that E8.5-E9.5 wild-type placenta expressed HOP/NECC1 in the giant cell and spongiotrophoblast layers. HOP/NECC1 (-/-) placenta exhibited marked propagation of giant cell layers and, in turn reduction of spongiotrophoblast formation. We demonstrated SRF transcriptional activity increased in the differentiating trophoblasts and forced expression of SRF in a trophoblast stem (TS) cell line induces the differentiation into giant cells. Negative regulation of SRF (serum response factor) by the binding of HOP/NECC1 protein contributed at least in part to the generation of these placental defects. Gradual induction of HOP/NECC1 in response to differentiation stimuli may result in the decision to differentiate into a particular type of trophoblastic cell lineage and result in non-lethal defects shown by the HOP/NECC1 (-/-) placentas.
Assuntos
Diferenciação Celular , Proteínas de Homeodomínio/fisiologia , Trofoblastos/citologia , Proteínas Supressoras de Tumor/fisiologia , Animais , Linhagem da Célula , Feminino , Perfilação da Expressão Gênica , Genótipo , Proteínas de Homeodomínio/genética , Humanos , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Fatores de Tempo , Proteínas Supressoras de Tumor/genéticaRESUMO
Complete hydatidiform moles (CHMs) are a type of androgenetic fertilization without an ovum. Cases of CHM exhibit a generalized swelling of the villi and are known to be highly associated with persistent disease or carcinoma. In contrast, partial hydatidiform moles (PHMs) also show characteristic hydropic changes among the villi, but the incidence of secondary disease is relatively low. Because PHMs are fertilized by one ovum and two sperm and CHMs are fertilized by one or two sperm alone, we considered whether or not maternally imprinted genes might be useful for achieving a differential diagnosis. The validity of the imprinted genes in CHMs was assessed by implementation of a microarray technique. Among the genes examined, TSSC3, SLC22A1L, KCNQ1, and Decorin were shown to be down-regulated, and TSSC3 was the most markedly suppressed of these genes. In this study, 20 cases of CHM, the diagnosis of which was confirmed by DNA polymorphism, were investigated. In all of these cases, the expression of TSSC3 was completely absent, as determined by Western blot analysis. Conversely, 12 cases of PHM, also diagnosed by DNA polymorphism, were examined here; in all of these 12 cases, TSSC3 was found to be expressed normally. Immunohistochemical (IHC) analysis also produced the same results. The complete silencing of TSSC3 in cases of CHM will provide a novel, convenient strategy for the diagnosis of molar lesions in the placenta.
