ABSTRACT
ABSTRACT Objective: To verify the physiological action of triiodothyronine T3 on the expression of transforming growth factor α (TGFA) mRNA in MCF7 cells by inhibition of RNA Polymerase II and the MAPK/ERK pathway Materials and methods: The cell line was treated with T3 at a physiological dose (10−9M) for 10 minutes, 1 and 4 hour (h) in the presence or absence of the inhibitors, α-amanitin (RNA polymerase II inhibitor) and PD98059 (MAPK/ERK pathway inhibitor). TGFA mRNA expression was analyzed by RT-PCR. For data analysis, we used ANOVA, complemented with the Tukey test and Student t-test, with a minimum significance of 5%. Results: T3 increases the expression of TGFA mRNA in MCF7 cells in 4 h of treatment. Inhibition of RNA polymerase II modulates the effect of T3 treatment on the expression of TGFA in MCF7 cells. Activation of the MAPK/ERK pathway is not required for T3 to affect the expression of TGFA mRNA. Conclusion: Treatment with a physiological concentration of T3 after RNA polymerase II inhibition altered the expression of TGFA. Inhibition of the MAPK/ERK pathway after T3 treatment does not interfere with the TGFA gene expression in a breast adenocarcinoma cell line.
Subject(s)
Humans , Female , Triiodothyronine/genetics , Breast Neoplasms/genetics , Adenocarcinoma/genetics , Gene Expression Regulation, Neoplastic/genetics , Transforming Growth Factor alpha/genetics , MAP Kinase Signaling System/genetics , Triiodothyronine/metabolism , Triiodothyronine/pharmacology , Proto-Oncogenes/genetics , Breast Neoplasms/metabolism , RNA, Messenger/genetics , Adenocarcinoma/metabolism , Transforming Growth Factor alpha/drug effects , Transforming Growth Factor alpha/metabolism , Cell Line, Tumor/metabolism , MCF-7 Cells/metabolismABSTRACT
OBJECTIVE: We sought to identify glycolysis, glycogenolysis, lipolysis, Krebs cycle, respiratory chain, and oxidative phosphorylation enzymes simultaneously regulated by T3 and cAMP. MATERIALS AND METHODS: We performed in silico analysis of 56 promoters to search for cis-cAMP (CREB) and cis-thyroid (TRE) response elements, considering UCP1, SERCA2 and glyceraldehyde 3-phosphate dehydrogenase as reference. Only regulatory regions with prior in vitro validation were selected. RESULTS: 29/56 enzymes presented potential TREs in their regulatory sequence, and some scored over 0.80 (better predictive value 1): citrate synthase, phosphoglucose isomerase, succinate dehydrogenases A/C, UCP3, UCP2, UCP4, UCP5, phosphoglycerate mutase, glyceraldehyde 3-P dehydrogenase, glucokinase, malate dehydrogenase, acyl-CoA transferase (thiolase), cytochrome a3, and lactate dehydrogenase. Moreover, some enzymes have not yet been described in the literature as genomically regulated by T3. CONCLUSION: Our results point to other enzymes which may possibly be regulated by T3 and CREB, and speculate their joint roles in contributing to the optimal thermogenic acclimation.
OBJETIVO: Identificar enzimas das vias da glicólise, glicogenólise, lipólise, ciclo de Krebs, cadeia respiratória e fosforilação oxidativa possivelmente reguladas por T3 e cAMP. MATERIAIS E MÉTODOS: Analisamos 56 genes metabólicos in silico mediante a identificação dos elementos cis de regulação gênica responsivos ao T3 e cAMP (TREs, thyroid response elements e CREs, cAMP response elements), utilizando como referência o promotor da UCP1, SERCA2 e gliceraldeído 3-fosfato desidrogenase. Selecionamos somente os promotores com estudo funcional prévio in vitro. RESULTADOS: 29/56 enzimas apresentaram TREs em suas regiões regulatórias, parte com escore > 0,80 (melhor valor preditivo 1): citrato sintase, fosfoglucose isomerase, succinato desidrogenase A/C, UCP3, UCP2, UCP4, UCP5, fosfoglicerato mutase, gliceraldeído 3-P desidrogenase, glucoquinase, malato desidrogenase, acil-CoA transferase (tiolase), citocromo a3, e lactato desidrogenase; parte desconhecida como regulada por T3. CONCLUSÃO: Os resultados do presente estudo apontam para novos genes regulados por T3 e cAMP e, por conseguinte, sua contribuição na regulação da termogênese.