RESUMO
OBJECTIVE: To investigate the expression of SMAD proteins in human thyroid tissues since the inactivation of TGF-beta/activin signaling components is reported in several types of cancer. Phosphorylated SMAD 2 and SMAD3 (pSMAD2/3) associated with the SMAD4 induce the signal transduction generated by TGF-beta and activin, while SMAD7 inhibits this intracellular signaling. Although TGF-beta and activin exert antiproliferative roles in thyroid follicular cells, thyroid tumors express high levels of these proteins. MATERIALS AND METHODS: The protein expression of SMADs was evaluated in multinodular goiter, follicular adenoma, papillary and follicular carcinomas by immunohistochemistry. RESULTS: The expression of pSMAD2/3, SMAD4 and SMAD7 was observed in both benign and malignant thyroid tumors. Although pSMAD2/3, SMAD4 and SMAD7 exhibited high cytoplasmic staining in carcinomas, the nuclear staining of pSMAD2/3 was not different between benign and malignant lesions. CONCLUSIONS: The finding of SMADs expression in thyroid cells and the presence of pSMAD2/3 and SMAD4 proteins in the nucleus of tumor cells indicates propagation of TGF-beta/activin signaling. However, the high expression of the inhibitory SMAD7, mostly in malignant tumors, could contribute to the attenuation of the SMADs antiproliferative signaling in thyroid carcinomas.
Assuntos
Ativinas/fisiologia , Proteínas Smad Reguladas por Receptor/metabolismo , Neoplasias da Glândula Tireoide/metabolismo , Fator de Crescimento Transformador beta/fisiologia , Adenoma/metabolismo , Carcinoma Papilar, Variante Folicular/metabolismo , Bócio Nodular/metabolismo , Humanos , Transdução de Sinais/fisiologia , Proteína Smad2/análise , Proteína Smad3/análise , Proteína Smad4/análise , Proteína Smad7/análiseRESUMO
OBJECTIVE: To investigate the expression of SMAD proteins in human thyroid tissues since the inactivation of TGF-β/activin signaling components is reported in several types of cancer. Phosphorylated SMAD 2 and SMAD3 (pSMAD2/3) associated with the SMAD4 induce the signal transduction generated by TGF-β and activin, while SMAD7 inhibits this intracellular signaling. Although TGF-β and activin exert antiproliferative roles in thyroid follicular cells, thyroid tumors express high levels of these proteins. MATERIALS AND METHODS: The protein expression of SMADs was evaluated in multinodular goiter, follicular adenoma, papillary and follicular carcinomas by immunohistochemistry. RESULTS: The expression of pSMAD2/3, SMAD4 and SMAD7 was observed in both benign and malignant thyroid tumors. Although pSMAD2/3, SMAD4 and SMAD7 exhibited high cytoplasmic staining in carcinomas, the nuclear staining of pSMAD2/3 was not different between benign and malignant lesions. CONCLUSIONS: The finding of SMADs expression in thyroid cells and the presence of pSMAD2/3 and SMAD4 proteins in the nucleus of tumor cells indicates propagation of TGF-β/activin signaling. However, the high expression of the inhibitory SMAD7, mostly in malignant tumors, could contribute to the attenuation of the SMADs antiproliferative signaling in thyroid carcinomas.
OBJETIVO: Investigar a expressão de proteínas SMAD em tecidos de tiroide humana desde que a inativação dos componentes da sinalização de TGF-β/activina é relatada em diversos tipos de câncer. SMAD 2 e SMAD3 fosforilados (pSMAD2/3) associados com SMAD4 induzem a transmissão do sinal gerado por TGF-β e activina, enquanto SMAD7 inibe essa sinalização intracelular. Embora TGF-β e activina exerçam efeitos antiproliferativos nas células foliculares da tiroide, tumores de tiroide expressam altos níveis dessas proteínas. MATERIAIS E MÉTODOS: A expressão proteica de SMADs foi avaliada em bócio multinodular, adenoma folicular, carcinomas papilífero e folicular por imuno-histoquímica. RESULTADOS: A expressão de pSMAD2/3, SMAD4 e SMAD7 foi observada tanto em tumores benignos como malignos da tiroide. Embora pSMAD2/3, SMAD4 e SMAD7 exibissem alta positividade citoplasmática em carcinomas, a positividade nuclear de pSMAD2/3 não foi diferente entre lesões benignas e malignas da tiroide. CONCLUSÕES: O achado da expressão de SMADs em células tiroidianas e a presença das proteínas pSMAD2/3 e SMAD4 no núcleo de células tumorais indicam propagação da sinalização TGF-β/activina. Contudo, a alta expressão de SMAD7 inibitório, principalmente em tumores malignos, poderia contribuir para atenuação da sinalização antiproliferativa de SMADs em carcinomas de tiroide.
Assuntos
Humanos , Ativinas/fisiologia , Proteínas Smad Reguladas por Receptor/metabolismo , Neoplasias da Glândula Tireoide/metabolismo , Fator de Crescimento Transformador beta/fisiologia , Adenoma/metabolismo , Carcinoma Papilar, Variante Folicular/metabolismo , Bócio Nodular/metabolismo , Transdução de Sinais/fisiologia , /análise , /análise , /análise , /análiseRESUMO
TGFbeta and activin are members of the TGFbeta superfamily and play a wide role in development, proliferation and apoptosis. These growth factors exert their biological effects by binding to the type I and II membrane receptors to transduce their signalling through the nucleus by phosphorylation of R-SMADs (SMAD 2/3) and co-SMADs (Smad 4). The proper control of TGFbeta/activin pathway is negatively regulated by inhibitory SMAD (SMAD7) and by E3 ubiquitination enzymes (Smurfs). Physiologically, TGFbeta and activin act as potent growth inhibitors in thyroid follicular cell. Thus, alterations in the receptors and components of SMAD signalling pathway are associated with several types of tumors. Since TGFbeta and activin generate their intracellular signalling through the same components of the SMAD pathway, the unbalance of this pathway impairs both of anti-mitogenic signals in the cell. This review addresses aspects of the molecular mechanisms in the understanding of resistance to the growth inhibitory effects of TGFbeta and activin due to the disequilibrium in the SMAD inhibitory pathway in thyroid neoplasia.
Assuntos
Ativinas/metabolismo , Transdução de Sinais/fisiologia , Proteínas Smad/metabolismo , Neoplasias da Glândula Tireoide/metabolismo , Transativadores/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Linhagem Celular , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Humanos , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação , Receptores de Fatores de Crescimento/genética , Receptores de Fatores de Crescimento/metabolismo , Proteína Smad7 , Neoplasias da Glândula Tireoide/genética , Transativadores/genética , Transcrição Gênica , Ubiquitina-Proteína LigasesRESUMO
TGFbeta e activina são membros da superfamília TGFbeta e desempenham um amplo papel no desenvolvimento, proliferação e apoptose. Estes fatores de crescimento exercem seus efeitos biológicos ligando-se a receptores de membrana do tipo I e do tipo II que transduzem a sinalização até o núcleo através da fosforilação das proteínas R-SMADs (SMAD 2/3) e co-SMADs (SMAD4). O controle apropriado da via de TGFbeta/activina ainda depende da regulação negativa exercida pelo SMAD inibitório (SMAD7) e pelas enzimas E3 de ubiquitinação (Smurfs). Fisiologicamente, TGFbeta e activina atuam como potentes inibidores da proliferação na célula folicular tiroidiana. Desta forma, alterações de receptores e componentes da via de sinalização SMAD estão associadas a diferentes tipos de tumores. Desde que TGFbeta e activina geram sua sinalização intracelular utilizando os mesmos componentes da via SMAD, o desequilíbrio desta via prejudica dois processos anti-mitogênicos da célula. Nesta revisão, enfocamos aspectos que indicam o mecanismo de resistência ao efeito inibitório de TGFbeta e activina ocasionado pelo desequilíbrio da via de sinalização SMAD nas neoplasias da tiróide.
TGFbeta and activin are members of the TGFbeta superfamily and play a wide role in development, proliferation and apoptosis. These growth factors exert their biological effects by binding to the type I and II membrane receptors to transduce their signalling through the nucleus by phosphorylation of R-SMADs (SMAD 2/3) and co-SMADs (Smad 4). The proper control of TGFbeta/activin pathway is negatively regulated by inhibitory SMAD (SMAD7) and by E3 ubiquitination enzymes (Smurfs). Physiologically, TGFbeta and activin act as potent growth inhibitors in thyroid follicular cell. Thus, alterations in the receptors and components of SMAD signalling pathway are associated with several types of tumors. Since TGFbeta and activin generate their intracellular signalling through the same components of the SMAD pathway, the unbalance of this pathway impairs both of anti-mitogenic signals in the cell. This review addresses aspects of the molecular mechanisms in the understanding of resistance to the growth inhibitory effects of TGFbeta and activin due to the disequilibrium in the SMAD inhibitory pathway in thyroid neoplasia.
Assuntos
Humanos , Ativinas/metabolismo , Transdução de Sinais/fisiologia , Proteínas Smad/metabolismo , Neoplasias da Glândula Tireoide/metabolismo , Transativadores/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Linhagem Celular , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação , Receptores de Fatores de Crescimento/genética , Receptores de Fatores de Crescimento/metabolismo , Transcrição Gênica , Neoplasias da Glândula Tireoide/genética , Transativadores/genética , Ubiquitina-Proteína LigasesRESUMO
A detailed genome mapping analysis of 213,636 expressed sequence tags (EST) derived from nontumor and tumor tissues of the oral cavity, larynx, pharynx, and thyroid was done. Transcripts matching known human genes were identified; potential new splice variants were flagged and subjected to manual curation, pointing to 788 putatively new alternative splicing isoforms, the majority (75%) being insertion events. A subset of 34 new splicing isoforms (5% of 788 events) was selected and 23 (68%) were confirmed by reverse transcription-PCR and DNA sequencing. Putative new genes were revealed, including six transcripts mapped to well-studied chromosomes such as 22, as well as transcripts that mapped to 253 intergenic regions. In addition, 2,251 noncoding intronic RNAs, eventually involved in transcriptional regulation, were found. A set of 250 candidate markers for loss of heterozygosis or gene amplification was selected by identifying transcripts that mapped to genomic regions previously known to be frequently amplified or deleted in head, neck, and thyroid tumors. Three of these markers were evaluated by quantitative reverse transcription-PCR in an independent set of individual samples. Along with detailed clinical data about tumor origin, the information reported here is now publicly available on a dedicated Web site as a resource for further biological investigation. This first in silico reconstruction of the head, neck, and thyroid transcriptomes points to a wealth of new candidate markers that can be used for future studies on the molecular basis of these tumors. Similar analysis is warranted for a number of other tumors for which large EST data sets are available.
Assuntos
Perfilação da Expressão Gênica , Marcadores Genéticos , Neoplasias de Cabeça e Pescoço/genética , RNA Mensageiro/genética , Neoplasias da Glândula Tireoide/genética , Transcrição Gênica , Processamento Alternativo , Etiquetas de Sequências Expressas , Neoplasias de Cabeça e Pescoço/metabolismo , Humanos , Laringe/metabolismo , Boca/metabolismo , Faringe/metabolismo , Reação em Cadeia da Polimerase , Isoformas de Proteínas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Glândula Tireoide/metabolismo , Neoplasias da Glândula Tireoide/metabolismoRESUMO
Thyroid tumors originate from two cell types: 1) medullar carcinoma from parafolicullar cells and 2) the tumors derived from follicular epithelial cells, which include multinodular goiter, adenomas, differentiated carcinomas (papillary and follicular carcinoma) and undifferentiated carcinoma (anaplastic carcinoma). Because of the tumors distinct biological behavior, there is a requirement for a specific therapeutic approach. Some thyroid cancer specific mutations have been identified using molecular biology and more recently, genomic methodology. We now understand much of the alterations that occur in the expression of growth factors, receptors and the intracellular signaling pathway. However, none of these have yet proven to be efficient as a marker for diagnosis and prognosis, nor are they helpful in establishing a targeted therapeutic approach. In this review, we will discuss the main aspects of thyroid tumorigenesis and evaluate the potential of these factors as markers for thyroid follicular neoplasia.
Assuntos
Neoplasias da Glândula Tireoide/diagnóstico , Neoplasias da Glândula Tireoide/genética , Biomarcadores Tumorais/análise , Biomarcadores Tumorais/biossíntese , Proteínas de Ciclo Celular/fisiologia , Rearranjo Gênico , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/fisiologiaRESUMO
Um marcador biológico ideal deve ser específico e sensível para identificar o tipo tumoral e caracterizar o estágio da progressão neoplásica. Os tumores de tiróide originam-se de dois tipos celulares: 1) carcinoma medular originário de células parafoliculares; e 2) as neoplasias de células epiteliais foliculares, que incluem bócio, adenomas, carcinomas diferenciados (carcinoma papilífero e carcinoma folicular) e carcinoma indiferenciado (carcinoma anaplásico). O comportamento biológico distinto faz com que cada tipo tumoral necessite de uma conduta terapêutica específica. O conhecimento acumulado ao longo destes anos, utilizando métodos de biologia molecular e, mais recentemente, a genômica, identificou mutações específicas de câncer de tiróide e, atualmente, entendemos muito das alterações que ocorrem na expressão de fatores de crescimento, seus receptores e proteínas sinalizadoras intracelular nas neoplasias tiroidianas. Contudo, apesar desses, até o momento não dispomos de um marcador eficiente que auxilie no diagnóstico e prognóstico e, conseqüentemente, para indicação de uma terapêutica mais adequada. Nesta revisão, discutiremos os principais aspectos relacionados à tumorigênese tiroidiana, avaliando o potencial destes fatores como marcador em neoplasia folicular de tiróide.
Assuntos
Humanos , Neoplasias da Glândula Tireoide/diagnóstico , Neoplasias da Glândula Tireoide/genética , Proteínas de Ciclo Celular/fisiologia , Rearranjo Gênico , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Biomarcadores Tumorais/análise , Biomarcadores Tumorais/biossínteseRESUMO
Activins are dimeric proteins of the transforming growth factor beta superfamily, which exhibit multiple functions in gonadal and extragonadal tissues. Expression of activin A, composed of two betaA subunits, has been shown in the thyroid, whereas there has been no study regarding activin B (betaBbetaB) in this gland. In other tissues, such as the gonads, pancreas, and adrenal cortex, expression of both activin betaA and activin betaB has been described. In this study, we detected activin betaB mRNA and protein expression using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry in rat experimental goiter and in human thyroid, including multinodular goiter, follicular adenoma, papillary carcinoma, and follicular carcinoma. Activin betaA mRNA and protein expression was also investigated in rat and human thyroid tissue. The expression of both activin betaB and activin betaA was highest in rat methimazole-induced goiter and in human follicular adenoma, and papillary and follicular carcinomas when compared with multinodular goiter and normal thyroid tissue. The increased expression of activin betaB as well as activin betaA, observed in this study, suggests that activin B and activin A may be involved in the proliferative and neoplastic processes of the thyroid.
Assuntos
Bócio/metabolismo , Subunidades beta de Inibinas/biossíntese , Neoplasias da Glândula Tireoide/metabolismo , Animais , Sequência de Bases , Primers do DNA/genética , Bócio/induzido quimicamente , Bócio/patologia , Humanos , Imuno-Histoquímica/métodos , Subunidades beta de Inibinas/genética , Masculino , Metimazol/toxicidade , Dados de Sequência Molecular , RNA Mensageiro/biossíntese , Ratos , Ratos Wistar , Glândula Tireoide/citologia , Glândula Tireoide/metabolismo , Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/patologiaRESUMO
Galectin-3 is a protein of the lectin family that has been associated with neoplastic processes in various tissues. In the thyroid, expression of this protein has been described in differentiated follicular cancer, suggesting that the immunohistochemical study of galectin-3 may be a potential marker of malignancy in thyroid neoplasms. The confirmation of these results may represent an extremely useful tool for presurgical diagnosis and medical conduct. In this study, galectin-3 protein and mRNA expression were analyzed in the thyroid tissues from 87 patients with histomorphological diagnosis of multinodular goiter (MNG) (n = 24), follicular adenoma (n = 31), follicular carcinoma (n = 20), papillary carcinoma (n = 12), and five normal tissues. Galectin-3 protein expression was detected by immunohistochemical method in light, fluorescence, and confocal microscopy, using monoclonal antibody. Galectin-3 mRNA expression was detected by the RT-PCR method. Our results showed that the majority of carcinomas expressed galectin-3 protein (follicular, 90%; papillary, 100%). However, in contrast to the previously published data, benign lesions also expressed galectin-3 (adenoma, 45%; MNG, 17%). We further demonstrated by RT-PCR that thyroid tissues with diagnosis of adenoma and MNG-expressed galectin-3 mRNA. Although the galectin-3 immunostaining demonstrated a sensitivity of 93.8% in the identification of cancer, the accuracy in the distinction between benign and malignant tissues was 77.0%. This accuracy was even lower (68.6%) when the galectin-3 expression in follicular adenoma was compared with follicular carcinoma. Thus, the use of galectin-3 immunodetection as a molecular marker for thyroid carcinoma must be interpreted with caution, particularly in the differentiation between thyroid follicular carcinoma and follicular adenoma.
