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1.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-30962160

RESUMO

Although iodine nutrition in Spain has improved in recent years, the problem is not completely resolved. It is necessary that health institutions establish measures to ensure an adequate iodine nutrition of the population, especially among the highest risk groups (children and adolescents, women of childbearing age, pregnant women and nursing mothers). A low salt intake should be advised, but it should be iodized. It is also imperative that food control agencies establish effective control over adequate iodization of salt. Indicators on iodine nutrition should be included in future health surveys. The EUthyroid study and the Krakow Declaration on iodine nutrition provide an opportunity to set up a pan-European plan for the prevention of iodine deficiency that should be considered and used by health authorities.

2.
Endocr Relat Cancer ; 25(4): R225-R245, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29437784

RESUMO

Iodide (I-) metabolism is crucial for the synthesis of thyroid hormones (THs) in the thyroid and the subsequent action of these hormones in the organism. I- is principally transported by the sodium iodide symporter (NIS) and by the anion exchanger PENDRIN, and recent studies have demonstrated the direct participation of new transporters including anoctamin 1 (ANO1), cystic fibrosis transmembrane conductance regulator (CFTR) and sodium multivitamin transporter (SMVT). Several of these transporters have been found expressed in various tissues, implicating them in I- recycling. New research supports the exciting idea that I- participates as a protective antioxidant and can be oxidized to hypoiodite, a potent oxidant involved in the host defense against microorganisms. This was possibly the original role of I- in biological systems, before the appearance of TH in evolution. I- per se participates in its own regulation, and new evidence indicates that it may be antineoplastic, anti-proliferative and cytotoxic in human cancer. Alterations in the expression of I- transporters are associated with tumor development in a cancer-type-dependent manner and, accordingly, NIS, CFTR and ANO1 have been proposed as tumor markers. Radioactive iodide has been the mainstay adjuvant treatment for thyroid cancer for the last seven decades by virtue of its active transport by NIS. The rapid advancement of techniques that detect radioisotopes, in particular I-, has made NIS a preferred target-specific theranostic agent.

3.
Endocrinol Diabetes Nutr ; 64(2): 109-117, 2017 02.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-28440775

RESUMO

The association between diabetes and cancer was hypothesized almost one century ago. Today, a vast number of epidemiological studies support that obese and diabetic populations are more likely to experience tissue-specific cancers, but the underlying molecular mechanisms remain unknown. Obesity, diabetes, and cancer share many hormonal, immune, and metabolic changes that may account for the relationship between diabetes and cancer. In addition, antidiabetic treatments may have an impact on the occurrence and course of some cancers. Moreover, some anticancer treatments may induce diabetes. These observations aroused a great controversy because of the ethical implications and the associated commercial interests. We report an epidemiological update from a mechanistic perspective that suggests the existence of many common and differential individual mechanisms linking obesity and type 1 and 2 diabetes mellitus to certain cancers. The challenge today is to identify the molecular links responsible for this association. Classification of cancers by their molecular signatures may facilitate future mechanistic and epidemiological studies.

4.
Br J Cancer ; 114(7): 716-22, 2016 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-26908326

RESUMO

Increasing evidence suggests a complex relationship between obesity, diabetes and cancer. Here we review the evidence for the association between obesity and diabetes and a wide range of cancer types. In many cases the evidence for a positive association is strong, but for other cancer types a more complex picture emerges with some site-specific cancers associated with obesity but not to diabetes, and some associated with type I but not type II diabetes. The evidence therefore suggests the existence of cumulative common and differential mechanisms influencing the relationship between these diseases. Importantly, we highlight the influence of antidiabetics on cancer and antineoplastic agents on diabetes and in particular that antineoplastic targeting of insulin/IGF-1 signalling induces hyperglycaemia that often evolves to overt diabetes. Overall, a coincidence of diabetes and cancer worsens outcome and increases mortality. Future epidemiology should consider dose and time of exposure to both disease and treatment, and should classify cancers by their molecular signatures. Well-controlled studies on the development of diabetes upon cancer treatment are necessary and should identify the underlying mechanisms responsible for these reciprocal interactions. Given the global epidemic of diabetes, preventing both cancer occurrence in diabetics and the onset of diabetes in cancer patients will translate into a substantial socioeconomic benefit.


Assuntos
Diabetes Mellitus Tipo 2/epidemiologia , Hipoglicemiantes/farmacologia , Neoplasias/epidemiologia , Obesidade/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/etiologia , Humanos , Neoplasias/etiologia
5.
Antioxid Redox Signal ; 24(15): 855-66, 2016 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-26650895

RESUMO

AIMS: The sodium-iodide symporter (NIS) mediates the uptake of I(-) by the thyroid follicular cell and is essential for thyroid hormone biosynthesis. Nis expression is stimulated by thyroid-stimulating hormone (TSH) and also requires paired box 8 (Pax8) to bind to its promoter. Pax8 binding activity depends on its redox state by a mechanism involving thioredoxin/thioredoxin reductase-1 (Txn/TxnRd1) reduction of apurinic/apyrimidinic endonuclease 1 (Ape1). In this study, we investigate the role of Se in Nis expression. RESULTS: Selenium increases TSH-induced Nis expression and activity in rat thyroid cells. The stimulatory effect of Se occurs at the transcriptional level and is only observed for Nis promoters containing a Pax8 binding site in the Nis upstream enhancer, suggesting that Pax8 is involved in this effect. In fact, Se increases Pax8 expression and its DNA-binding capacity, and in Pax8-silenced rat thyroid cells, Nis is not Se responsive. By inhibiting Ape1 and TxnRd1 functions, we found that both enzymes are crucial for TSH and TSH plus Se stimulation of Pax8 activity and mediate the Nis response to Se treatment. INNOVATION: We describe that Se increases Nis expression and activity. We demonstrate that this effect is dependent on the redox functions of Ape1 and Txn/TxnRd1 through control of the DNA binding activity of Pax8. CONCLUSION: Nis expression is controlled by Txn/Ape1 through a TSH/Se-dependent mechanism. These findings open a new field of study regarding the regulation of Nis activity in thyroid cells. Antioxid. Redox Signal. 24, 855-866.


Assuntos
DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Fator de Transcrição PAX8/metabolismo , Selênio/fisiologia , Simportadores/genética , Tiorredoxinas/fisiologia , Tireotropina/fisiologia , Animais , Linhagem Celular , Glutationa Peroxidase/metabolismo , Oxirredução , Ligação Proteica , Ratos , Simportadores/metabolismo , Tiorredoxina Redutase 1/metabolismo , Transcrição Genética , Ativação Transcricional
6.
Biochim Biophys Acta ; 1839(11): 1141-50, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25091498

RESUMO

Minutes after ingestion of fat or carbohydrates, vesicles stored in enteroendocrine cells release their content of incretin peptide hormones that, together with absorbed glucose, enhance insulin secretion by beta-pancreatic cells. Freshly-made incretins must therefore be packed into new vesicles in anticipation of the next meal with cells adjusting new incretin production to be proportional to the level of previous insulin release and absorbed blood glucose. Here we show that insulin stimulates the expression of the major human incretin, glucose-dependent insulinotropic peptide (GIP) in enteroendocrine cells but requires glucose to do it. Akt-dependent release of FoxO1 and glucose-dependent binding of LEF1/ß-catenin mediate induction of Gip expression while insulin-induced phosphorylation of ß-catenin does not alter its localization or transcriptional activity in enteroendocrine cells. Our results reveal a glucose-regulated feedback loop at the entero-insular axis, where glucose levels determine basal and insulin-induced Gip expression; GIP stimulation of insulin release, physiologically ensures a fine control of glucose homeostasis. How enteroendocrine cells adjust incretin production to replace incretin stores for future use is a key issue because GIP malfunction is linked to all forms of diabetes.


Assuntos
Fatores de Transcrição Forkhead/genética , Polipeptídeo Inibidor Gástrico/genética , Glucose/farmacologia , Insulina/farmacologia , Fator 1 de Ligação ao Facilitador Linfoide/genética , beta Catenina/genética , Células Cultivadas , Células Enteroendócrinas/efeitos dos fármacos , Células Enteroendócrinas/metabolismo , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead/metabolismo , Polipeptídeo Inibidor Gástrico/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Fator 1 de Ligação ao Facilitador Linfoide/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , beta Catenina/metabolismo
7.
J Clin Endocrinol Metab ; 99(7): E1199-208, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24708099

RESUMO

CONTEXT: The sodium iodide symporter (NIS) mediates active transport of iodide into the thyroid and the lactating mammary glands and is highly expressed in thyroid and breast carcinomas. NIS is clinically very relevant because it allows the treatment with radioiodine of thyroid cancer patients. OBJECTIVE: In this study we wanted to explore whether NIS is expressed in the ovary and in ovarian cancer. METHODS/PATIENTS: Methods included NIS and paired box 8 expression and function in ovarian cancer patients and rats by immunochemistry, immunoblot, RT-PCR, and iodide uptake. RESULTS: Here we demonstrate for the first time that NIS is expressed in the ovary and fallopian tube and actively accumulates significant levels of radioiodide in vivo. In a large survey of menstruating women receiving radioiodide for medical purposes, 15% showed significant uptake in the normal reproductive tract. Ovarian NIS activity is influenced by the estrous cycle stage in rats, being up-regulated during peak levels of estrogens occurring immediately before the ovulation. We unveil that the regulatory mechanism underlying this phenomenon is based on the functional cooperation of estrogen receptor-α and paired box 8. We also show that NIS is highly expressed in ovarian cancer, predicting a poor prognosis in these patients. CONCLUSIONS: These results provide the basis that will help minimize the impact of therapeutic doses of radioiodide on gonadal function. We also suggest that NIS is a new ovarian cancer marker, opening a door for the use of radioiodide in the diagnosis and treatment of ovarian cancer patients.


Assuntos
Genitália Feminina/metabolismo , Iodo/metabolismo , Neoplasias Epiteliais e Glandulares/diagnóstico , Neoplasias Ovarianas/diagnóstico , Simportadores/fisiologia , Adulto , Animais , Carcinoma Epitelial do Ovário , Feminino , Genitália Feminina/patologia , Células HeLa , Humanos , Pessoa de Meia-Idade , Neoplasias Epiteliais e Glandulares/genética , Neoplasias Epiteliais e Glandulares/metabolismo , Neoplasias Epiteliais e Glandulares/patologia , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Prognóstico , Ratos , Ratos Wistar
8.
J Mol Endocrinol ; 52(1): R51-66, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24049067

RESUMO

Extensive epidemiological studies suggest that the diabetic population is at higher risk of site-specific cancers. The diabetes-cancer link has been hypothesized to rely on various hormonal (insulin, IGF1, adipokines), immunological (inflammation), or metabolic (hyperglycemia) characteristics of the disease and even on certain treatments. Inflammation may have an important but incompletely understood role. As a growth factor, insulin directly, or indirectly through IGF1, has been considered the major link between diabetes and cancer, while high glucose has been considered as a subordinate cause. Here we discuss the evidence that supports a role for insulin/IGF1 in general in cancer, and the mechanism by which hyperglycemia may enhance the appearance, growth and survival of diabetes-associated cancers. High glucose triggers several direct and indirect mechanisms that cooperate to promote cancer cell proliferation, migration, invasion and immunological escape. In particular, high glucose enhancement of WNT/ß-catenin signaling in cancer cells promotes proliferation, survival and senescence bypass, and represents a previously unrecognized direct mechanism linking diabetes-associated hyperglycemia to cancer. Increased glucose uptake is a hallmark of tumor cells and may ensure enhanced WNT signaling for continuous proliferation. Mechanistically, high glucose unbalances acetylation through increased p300 acetyl transferase and decreased sirtuin 1 deacetylase activity, leading to ß-catenin acetylation at lysine K354, a requirement for nuclear accumulation and transcriptional activation of WNT-target genes. The impact of high glucose on ß-catenin illustrates the remodeling of cancer-associated signaling pathways by metabolites. Metabolic remodeling of cancer-associated signaling will receive much research attention in the coming years. Future epidemiological studies may be guided and complemented by the identification of these metabolic interplays. Together, these studies should lead to the development of new preventive strategies for diabetes-associated cancers.


Assuntos
Complicações do Diabetes/metabolismo , Neoplasias/etiologia , Neoplasias/metabolismo , Acetilação , Animais , Glicemia , Complicações do Diabetes/epidemiologia , Glucose/metabolismo , Humanos , Hiperglicemia/complicações , Hiperglicemia/metabolismo , Hiperinsulinismo/complicações , Hiperinsulinismo/metabolismo , Neoplasias/epidemiologia , Risco , Transdução de Sinais , Proteínas Wnt/metabolismo , beta Catenina/metabolismo
9.
Mol Cell ; 49(3): 474-86, 2013 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-23273980

RESUMO

Nuclear accumulation of ß-catenin, a widely recognized marker of poor cancer prognosis, drives cancer cell proliferation and senescence bypass and regulates incretins, critical regulators of fat and glucose metabolism. Diabetes, characterized by elevated blood glucose levels, is associated with increased cancer risk, partly because of increased insulin growth factor 1 signaling, but whether elevated glucose directly impacts cancer-associated signal-transduction pathways is unknown. Here, we show that high glucose is essential for nuclear localization of ß-catenin in response to Wnt signaling. Glucose-dependent ß-catenin nuclear retention requires lysine 354 and is mediated by alteration of the balance between p300 and sirtuins that trigger ß-catenin acetylation. Consequently ß-catenin accumulates in the nucleus and activates target promoters under combined glucose and Wnt stimulation, but not with either stimulus alone. Our results reveal a mechanism by which high glucose enhances signaling through the cancer-associated Wnt/ß-catenin pathway and may explain the increased frequency of cancer associated with obesity and diabetes.


Assuntos
Glucose/farmacologia , Neoplasias/metabolismo , Via de Sinalização Wnt/efeitos dos fármacos , beta Catenina/metabolismo , Acetilação/efeitos dos fármacos , Linhagem Celular Tumoral , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Cromatina/metabolismo , Citosol/efeitos dos fármacos , Citosol/metabolismo , Proteína p300 Associada a E1A/metabolismo , Polipeptídeo Inibidor Gástrico/genética , Polipeptídeo Inibidor Gástrico/metabolismo , Humanos , Cloreto de Lítio/farmacologia , Fator 1 de Ligação ao Facilitador Linfoide/metabolismo , Neoplasias/patologia , Regiões Promotoras Genéticas/genética , Ligação Proteica/efeitos dos fármacos , Estabilidade Proteica/efeitos dos fármacos , Sirtuínas/metabolismo , Fatores de Transcrição TCF/metabolismo , Transcrição Genética/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacos , Ativação Transcricional/genética , Proteína Wnt3A/farmacologia
10.
Mol Endocrinol ; 25(11): 1924-35, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21903721

RESUMO

The phenomenon that supraphysiological doses of iodide (I(-)) temporarily inhibit thyroid hormone synthesis is known as thyroid iodide autoregulation. Recovery of thyroid function has been attributed to sodium-iodide symporter (NIS) inhibition, but the diversity of available data makes it difficult to reach definitive conclusions. Iodide excess induces reactive oxygen species production and cell toxicity. However, the roles of the oxidative state of the cell and antioxidant selenoproteins in I(-) autoregulation have never been explored. Here we analyze the effects of high I(-) doses in rat thyroids and in PCCl3 cells in the period comprising I(-) autoregulation (i.e. 0-72 h after I(-) administration), focusing on NIS expression, redox state, and the expression and activity of selenoproteins. Our results show that NIS mRNA inhibition by I(-) does not occur at the transcriptional level, because neither NIS promoter activity nor Pax8 expression or its binding to DNA was modulated. Because I(-) uptake was inhibited much earlier than NIS protein, and no effect was observed on its subcellular localization, we suggest that I(-) is inhibiting NIS in the plasma membrane. The increased reactive oxygen species production leads to an increase in thioredoxin reductase mRNA levels and enzyme activity, which reduces the oxidative stress. Inhibition of thioredoxin reductase at either gene expression or activity levels prevented NIS recovery, thus illustrating a new role played by this selenoprotein in the regulation of cell homeostasis and consequently in I(-) autoregulation.


Assuntos
Iodetos/farmacologia , Tiorredoxina Dissulfeto Redutase/metabolismo , Glândula Tireoide/enzimologia , Animais , Western Blotting , Linhagem Celular , Ensaio de Desvio de Mobilidade Eletroforética , Masculino , Oxirredução/efeitos dos fármacos , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Simportadores/genética , Simportadores/metabolismo , Tiorredoxina Dissulfeto Redutase/genética , Glândula Tireoide/efeitos dos fármacos , Glândula Tireoide/metabolismo
11.
J Clin Endocrinol Metab ; 96(9): E1435-43, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21697253

RESUMO

CONTEXT: Telomerase promoters (hTERT and hTR) are useful for transcriptional targeting in gene therapy models of cancer. Telomerase-driven expression of the sodium iodide symporter (NIS) in tumor cells has been successfully used as a reporter gene in vivo using positron emission tomography (PET) imaging. OBJECTIVE: The aim of this study was to investigate the NIS-mediated therapeutic effect of telomerase promoters in a wide variety of human cancer cell lines. DESIGN AND METHODS: Promoter fragments from either hTERT or hTR were used to drive the expression of NIS in cell lines derived from melanoma (M14), breast (MDA-MB-231), colon (HT-29), lung (H460), ovarian (OVCAR-3), and thyroid (TPC-1) carcinomas. Iodide uptake assays, protein immunodetection, and clonigenic assays were used to confirm NIS functional expression and the (131)I-mediated cytopathic effect. Tumor xenografts in mice were infected with hTERT and hTR and then treated using radioiodide. RESULTS: Both promoters were selectively active in cancer cells that were effectively killed by exposure to (131)I. One single dose of 1 mCi (131)I markedly suppressed tumor growth of melanoma-derived tumor xenografts compared with controls. This effect was more modest in colon cancer-derived xenografts in part due to the reduced infectivity and the tumor cystic nature. The therapeutic effect of hTR promoter was found to be stronger than that of hTERT promoter. CONCLUSIONS: These results demonstrate that telomerase-driven expression of NIS could potentially have applications for (131)I therapy of a wide variety of cancers. Additionally, this is the first study to report NIS-mediated (131)I therapy of melanoma tumors in vivo.


Assuntos
Terapia Genética/métodos , Neoplasias/radioterapia , Simportadores/genética , Telomerase/genética , Animais , Linhagem Celular Tumoral , Humanos , Radioisótopos do Iodo/uso terapêutico , Camundongos , Transplante de Neoplasias , Neoplasias/genética , Neoplasias/metabolismo , Regiões Promotoras Genéticas , Simportadores/metabolismo , Telomerase/metabolismo
12.
Eur J Nucl Med Mol Imaging ; 37(7): 1377-85, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20140612

RESUMO

PURPOSE: In vivo imaging of the spread of oncolytic viruses using the Na/I symporter (NIS) has been proposed. Here, we assessed whether the presence of NIS in the viral genome affects the therapeutic efficacy of the oncolytic adenovirus dl922-947 following intraperitoneal administration, in a mouse model of peritoneal ovarian carcinoma. METHODS: We generated AdAM7, a dl922-947 oncolytic adenovirus encoding the NIS coding sequence. Iodide uptake, NIS expression, infectivity and cell-killing activity of AdAM7, as well as that of relevant controls, were determined in vitro. In vivo, the propagation of this virus in the peritoneal cavity of tumour-bearing mice was determined using SPECT/CT imaging and its therapeutic efficacy was evaluated. RESULTS: In vitro infection of ovarian carcinoma IGROV-1 cells with ADAM7 led to functional expression of NIS. However, the insertion of NIS into the viral genome resulted in a loss of efficacy of the virus in terms of replication and cytotoxicity. In vivo, on SPECT/CT imaging AdAM7 was only detectable in the peritoneal cavity of animals bearing peritoneal ovarian tumours for up to 5 days after intraperitoneal administration. Therapeutic experiments in vivo demonstrated that AdAM7 is as potent as its NIS-negative counterpart. CONCLUSION: This study demonstrated that despite the detrimental effect observed in vitro, insertion of the reporter gene NIS in an oncolytic adenovirus did not affect its therapeutic efficacy in vivo. We conclude that NIS is a highly relevant reporter gene to monitor the fate of oncolytic adenovectors in live subjects.


Assuntos
Adenoviridae/fisiologia , Genes Reporter/genética , Imagem Molecular/métodos , Vírus Oncolíticos/fisiologia , Neoplasias Peritoneais/virologia , Simportadores/genética , Replicação Viral , Adenoviridae/genética , Animais , Linhagem Celular Tumoral , Feminino , Regulação Neoplásica da Expressão Gênica , Genoma Viral/genética , Injeções Intraperitoneais , Camundongos , Vírus Oncolíticos/genética , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/terapia , Neoplasias Ovarianas/virologia , Neoplasias Peritoneais/genética , Neoplasias Peritoneais/terapia
13.
Cancer Res ; 69(21): 8317-25, 2009 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-19861538

RESUMO

The activating mutation BRAF(V600E) is a frequent genetic event in papillary thyroid carcinomas (PTC) that predicts a poor prognosis, leading to loss of sodium/iodide symporter (NIS) expression and subsequent radioiodide-refractory metastatic disease. The molecular basis of such an aggressive behavior induced by BRAF remains unclear. Here, we show a mechanism through which BRAF induces NIS repression and promotes epithelial to mesenchimal transition and invasion based on the operation of an autocrine transforming growth factor (TGF)beta loop. BRAF induces secretion of functional TGFbeta and blocking TGFbeta/Smad signaling at multiple levels rescues BRAF-induced NIS repression. Although this mechanism is MAP/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK independent, secreted TGFbeta cooperates with MEK-ERK signaling in BRAF-induced cell migration, Matrigel invasion, and EMT. Consistent with this process, TGFbeta and other key components of TGFbeta signaling, such as TbetaRII and pSmad2, are overexpressed in human PTC, suggesting a widespread activation of this pathway by locally released TGFbeta. Moreover, this high TGFbeta/Smad activity is associated with PTC invasion, nodal metastasis, and BRAF status. Interestingly, TGFbeta is overexpressed in the invasive front, whereas NIS is preferentially expressed in the central regions of the tumors, suggesting that this negative correlation between TGFbeta and NIS occurs locally inside the tumor. Our study describes a novel mechanism of NIS repression in thyroid cancer and provides evidence that TGFbeta may play a key role in promoting radioiodide resistance and tumor invasion during PTC progression.


Assuntos
Carcinoma Papilar/patologia , Mutação/genética , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas B-raf/metabolismo , Simportadores/genética , Neoplasias da Glândula Tireoide/patologia , Fator de Crescimento Transformador beta/metabolismo , Adulto , Comunicação Autócrina , Western Blotting , Carcinoma Papilar/genética , Carcinoma Papilar/metabolismo , Regulação para Baixo , Ensaio de Imunoadsorção Enzimática , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Imunofluorescência , Regulação Neoplásica da Expressão Gênica , Humanos , Técnicas Imunoenzimáticas , Iodetos/metabolismo , Luciferases/metabolismo , Masculino , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Invasividade Neoplásica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Fatores de Crescimento Transformadores beta/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína Smad2/metabolismo , Simportadores/metabolismo , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/metabolismo , Fator de Crescimento Transformador beta/genética , Células Tumorais Cultivadas
14.
Endocrinology ; 149(6): 3077-84, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18339708

RESUMO

I(-) is actively transported into thyrocytes via the Na+/I(-) symporter (NIS), a key glycoprotein located on the basolateral plasma membrane. The cDNA encoding rat NIS was identified in our laboratory, where an extensive structure/function characterization of NIS is being conducted. Several NIS mutants have been identified as causes of congenital I(-) transport defect (ITD), including V59E NIS. ITD is characterized by low thyroid I(-) uptake, low saliva/plasma I(-) ratio, hypothyroidism, and goiter and may cause mental retardation if untreated. Studies of other ITD-causing NIS mutants have revealed valuable information regarding NIS structure/function. V59E NIS was reported to exhibit as much as 30% of the activity of wild-type NIS. However, this observation was at variance with the patients' phenotype of total lack of activity. We have thoroughly characterized V59E NIS and studied several amino acid substitutions at position 59. We demonstrated that, in contrast to the previous report, V59E NIS is inactive, although it is properly targeted to the plasma membrane. Glu and all other charged amino acids or Pro at position 59 also yielded nonfunctional NIS proteins. However, I(-) uptake was rescued to different degrees by the other substitutions. Although the Km values for Na+ and I(-) were not altered in these active mutants, we found that the structural requirement for NIS function at position 59 is a neutral, helix-promoting amino acid. This result suggests that the region that contains V59 may be involved in intramembrane helix-helix interactions during the transport cycle without being in direct contact with the substrates.


Assuntos
Doenças Genéticas Inatas/genética , Simportadores/genética , Substituição de Aminoácidos , Animais , Transporte Biológico , Células COS , Cercopithecus aethiops , DNA Complementar/genética , Haplorrinos , Humanos , Iodetos/metabolismo , Cinética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Polimorfismo de Nucleotídeo Único , Conformação Proteica , Simportadores/química , Simportadores/metabolismo
15.
J Biol Chem ; 282(35): 25290-8, 2007 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-17606623

RESUMO

The Na+/I- symporter (NIS) is a key plasma membrane glycoprotein that mediates Na+-dependent active I- transport in the thyroid, lactating breast, and other tissues. The OH group of the side chain at position 354 in transmembrane segment (TMS) IX of NIS has been demonstrated to be essential for NIS function, as revealed by the study of the congenital I- transport defect-causing T354P NIS mutation. TMS IX has the most beta-OH group-containing amino acids (Ser and Thr) of any TMS in NIS. We have thoroughly characterized the functional significance of all Ser and Thr in TMS IX in NIS, as well as of other residues in TMS IX that are highly conserved in other transporters of the SLC5A protein family. Here we show that five beta-OH group-containing residues (Thr-351, Ser-353, Thr-354, Ser-356, and Thr-357) and Asn-360, all of which putatively face the same side of the helix in TMS IX, plus Asp-369, located in the membrane/cytosol interface, play key roles in NIS function and seem to be involved in Na+ binding/translocation.


Assuntos
Glicoproteínas/metabolismo , Iodo/metabolismo , Sódio/metabolismo , Simportadores/metabolismo , Sequência de Aminoácidos/genética , Substituição de Aminoácidos , Animais , Sítios de Ligação/genética , Glicoproteínas/genética , Transporte de Íons/fisiologia , Mutação de Sentido Incorreto , Especificidade de Órgãos/fisiologia , Ligação Proteica/genética , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína/genética , Ratos , Simportadores/genética
16.
Mol Endocrinol ; 20(5): 1121-37, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16439463

RESUMO

The sodium/iodide symporter (NIS) mediates a remarkably effective targeted radioiodide therapy in thyroid cancer; this approach is an emerging candidate for treating other cancers that express NIS, whether endogenously or by exogenous gene transfer. Thus far, the only extrathyroidal malignancy known to express functional NIS endogenously is breast cancer. Therapeutic efficacy in thyroid cancer requires that radioiodide uptake be maximized in tumor cells by manipulating well-known regulatory factors of NIS expression in thyroid cells, such as TSH, which stimulates NIS expression via cAMP. Similarly, therapeutic efficacy in breast cancer will likely depend on manipulating NIS regulation in mammary cells, which differs from that in the thyroid. Human breast adenocarcinoma MCF-7 cells modestly express endogenous NIS when treated with all-trans-retinoic acid (tRa). We report here that hydrocortisone and ATP each markedly stimulates tRa-induced NIS protein expression and plasma membrane targeting in MCF-7 cells, leading to at least a 100% increase in iodide uptake. Surprisingly, the adenyl cyclase activator forskolin, which promotes NIS expression in thyroid cells, markedly decreases tRa-induced NIS protein expression in MCF-7 cells. Isobutylmethylxanthine increases tRa-induced NIS expression in MCF-7 cells, probably through a purinergic signaling system independent of isobutylmethylxanthine's action as a phosphodiesterase inhibitor. We also observed that neither iodide, which at high concentrations down-regulates NIS in the thyroid, nor cAMP has a significant effect on NIS expression in MCF-7 cells. Our findings may open new strategies for breast-selective pharmacological modulation of functional NIS expression, thus improving the feasibility of using radioiodide to effectively treat breast cancer.


Assuntos
Trifosfato de Adenosina/farmacologia , Neoplasias da Mama/metabolismo , Hidrocortisona/farmacologia , Iodetos/metabolismo , Simportadores/agonistas , 1-Metil-3-Isobutilxantina/farmacologia , Inibidores de Adenilil Ciclases , Adenilil Ciclases/farmacologia , Transporte Biológico/efeitos dos fármacos , Membrana Celular/metabolismo , Células Cultivadas , Colforsina/farmacologia , Feminino , Humanos , Inibidores de Fosfodiesterase/farmacologia , Transdução de Sinais , Simportadores/metabolismo , Glândula Tireoide/metabolismo , Tretinoína/farmacologia
17.
Mol Endocrinol ; 19(11): 2847-58, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15976004

RESUMO

The Na+/I- symporter (NIS) is a key membrane glycoprotein that mediates active I- transport in the thyroid and other tissues. Upon isolation of the cDNA encoding NIS, 10 NIS mutations that cause congenital iodide transport defect have been identified. Three of these mutations (T354P, G395R, and Q267E) have been thoroughly characterized at the molecular level. All three NIS mutant proteins are correctly targeted to the plasma membrane; however, whereas Q267E displays minimal activity, T354P and G395R are inactive. Here, we show that in contrast to these mutants, G543E NIS matures only partially and is retained intracellularly; thus, it is not targeted properly to the cell surface, apparently because of faulty folding. These findings indicate that the G543 residue plays significant roles in NIS maturation and trafficking. Remarkably, NIS activity was rescued by small neutral amino acid substitutions (volume < 129 A3) at this position, suggesting that G543 is in a tightly packed region of NIS.


Assuntos
Iodetos/metabolismo , Iodo/deficiência , Simportadores/genética , Simportadores/metabolismo , Doenças da Glândula Tireoide/genética , Substituição de Aminoácidos , Animais , Transporte Biológico , Células COS , Membrana Celular/química , Cercopithecus aethiops , Citoplasma/química , Ácido Glutâmico/genética , Glicina/genética , Humanos , Mutação , Estrutura Secundária de Proteína , Transporte Proteico , Simportadores/análise , Transfecção , Vesículas Transportadoras/metabolismo
18.
J Cell Sci ; 117(Pt 5): 677-87, 2004 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-14734652

RESUMO

The Na(+)/I(-) symporter (NIS) is a key plasma membrane glycoprotein that mediates active iodide (I(-)) transport in the thyroid and other tissues. Since isolation of the cDNA encoding NIS (G. Dai, O. Levy, and N. Carrasco (1996) Nature 379, 458-460), ten mutations in NIS have been identified as causes of congenital iodide transport defect (ITD). Two of these mutations (T354P and G395R) have been thoroughly characterized at the molecular level. Both mutant NIS proteins are inactive but normally expressed and correctly targeted to the plasma membrane. The hydroxyl group at the beta-carbon of residue 354 is essential for NIS function, whereas the presence of a charged or large side-chain at position 395 interferes with NIS function. We report the extensive molecular analysis of the Q267E mutation in COS-7 cells transfected with rat or human Q267E NIS cDNA constructs. We used site-directed mutagenesis to engineer various residue substitutions into position 267. In contrast to previous suggestions that Q267E NIS was inactive, possibly because of a trafficking defect, we conclusively show that Q267E NIS is modestly active and properly targeted to the plasma membrane. Q267E NIS exhibited lower V(max) values for I(-) than wild-type NIS, suggesting that the decreased level of activity of Q267E NIS is due to a lower catalytic rate. That Q267E NIS retains even partial activity sets this ITD-causing mutant apart from T354P and G395R NIS. The presence of charged residues (of any polarity) other than Glu at position 267 rendered NIS inactive without affecting its expression or targeting, but substitution with neutral residues at this position was compatible with partial activity.


Assuntos
Iodetos/metabolismo , Mutação de Sentido Incorreto/genética , Simportadores/genética , Simportadores/metabolismo , Alanina/genética , Alanina/metabolismo , Substituição de Aminoácidos/genética , Animais , Asparagina/genética , Asparagina/metabolismo , Transporte Biológico , Biotinilação , Células COS , Linhagem Celular , Membrana Celular/metabolismo , Ácido Glutâmico/genética , Ácido Glutâmico/metabolismo , Glutamina/genética , Glutamina/metabolismo , Humanos , Cinética , Sódio/metabolismo , Glândula Tireoide/metabolismo
19.
Endocr Rev ; 24(1): 48-77, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12588808

RESUMO

The Na(+)/I(-) symporter (NIS) is an integral plasma membrane glycoprotein that mediates active I(-) transport into the thyroid follicular cells, the first step in thyroid hormone biosynthesis. NIS-mediated thyroidal I(-) transport from the bloodstream to the colloid is a vectorial process made possible by the selective targeting of NIS to the basolateral membrane. NIS also mediates active I(-) transport in other tissues, including salivary glands, gastric mucosa, and lactating mammary gland, in which it translocates I(-) into the milk for thyroid hormone biosynthesis by the nursing newborn. NIS provides the basis for the effective diagnostic and therapeutic management of thyroid cancer and its metastases with radioiodide. NIS research has proceeded at an astounding pace after the 1996 isolation of the rat NIS cDNA, comprising the elucidation of NIS secondary structure and topology, biogenesis and posttranslational modifications, transcriptional and posttranscriptional regulation, electrophysiological analysis, isolation of the human NIS cDNA, and determination of the human NIS genomic organization. Clinically related topics include the analysis of congenital I(-) transport defect-causing NIS mutations and the role of NIS in thyroid cancer. NIS has been transduced into various kinds of cancer cells to render them susceptible to destruction with radioiodide. Most dramatically, the discovery of endogenous NIS expression in more than 80% of human breast cancer samples has raised the possibility that radioiodide may be a valuable novel tool in breast cancer diagnosis and treatment.


Assuntos
Simportadores/genética , Simportadores/fisiologia , Doenças Autoimunes , Transporte Biológico/genética , Neoplasias da Mama , Regulação da Expressão Gênica , Humanos , Iodetos/metabolismo , Mutação , Especificidade de Órgãos , Transdução de Sinais , Doenças da Glândula Tireoide , Neoplasias da Glândula Tireoide , Transcrição Genética , Transfecção
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