Advances in Na(+)/I(-) symporter (NIS) research in the thyroid and beyond

Structure-Related Thyroid Disrupting Effect of Perfluorooctanesulfonate-like Substances in Zebrafish Larvae

Chlorinated polyfluorooctane ether sulfonate (6:2 Cl-PFESA), hydrogenated polyfluorooctane ether sulfonate (6:2 H-PFESA), and chlorinated polyfluorooctanesulfonate (Cl-PFOS) share structural similarities with the regulated perfluorooctanesulfonate (PFOS), but their toxic potential is rarely known. Here, the thyroid disrupting potential of these four compounds in zebrafish larvae has been comparably investigated. PFOS, Cl-PFOS, and 6:2 Cl-PFESA were accumulated in the larvae at similar levels, approximately 1.3-1.6 times higher than 6:2 H-PFESA. Additionally, PFOS, Cl-PFOS, and 6:2 Cl-PFESA exhibited stronger disruption than 6:2 H-PFESA on genetic regulation, particularly concerning thyroid hormone (TH) activation and action and on TH homeostasis in both free and total forms of thyroxine (T4) and 3,5,3'-triiodothyronine (T3). These results indicate that chlorination or oxygen insertion does not substantially alter the thyrotoxicity of PFOS, but hydrogenation mitigates it. Molecular docking analysis and the luciferase reporter gene assay provided mechanistic perspectives that the PFOS-like substances could competitively replace THs to bind with TH plasma and membrane transporters, thereby disrupting TH transport and action, respectively. Moreover, they are also potent to disrupt TH synthesis and activation through Na+/K+-dependent transport of I- or competitive binding to the sites of deiodinases.

The potential role of reprogrammed glucose metabolism: an emerging actionable codependent target in thyroid cancer

Although the incidence of thyroid cancer is increasing year by year, most patients, especially those with differentiated thyroid cancer, can usually be cured with surgery, radioactive iodine, and thyroid-stimulating hormone suppression. However, treatment options for patients with poorly differentiated thyroid cancers or radioiodine-refractory thyroid cancer have historically been limited. Altered energy metabolism is one of the hallmarks of cancer and a well-documented feature in thyroid cancer. In a hypoxic environment with extreme nutrient deficiencies resulting from uncontrolled growth, thyroid cancer cells utilize "metabolic reprogramming" to satisfy their energy demand and support malignant behaviors such as metastasis. This review summarizes past and recent advances in our understanding of the reprogramming of glucose metabolism in thyroid cancer cells, which we expect will yield new therapeutic approaches for patients with special pathological types of thyroid cancer by targeting reprogrammed glucose metabolism.

Maternal exposure to dietary uranium causes oxidative stress and thyroid disruption in zebrafish offspring

The contamination of uranium in aquatic ecosystems has raised growing global concern. However, the understanding of its chronic effects on aquatic organisms is limited, particularly with regards to transgenerational toxicity. In this study, we evaluated the maternal transfer risk of uranium using zebrafish. Sexually mature female zebrafish were exposed to 2 and 20 ng/g of uranium-spiked food for 28 days. The induced bioconcentration, thyroid disruption, and oxidative stress in both the adults (F0) and their embryos (F1) were further investigated. Element analysis showed that uranium was present in both F0 and F1, with higher concentrations observed in F1, indicating significant maternal offloading to the offspring. Meanwhile, an increased malformation and decreased swim speed were observed in the F1. Thyroid hormone analysis revealed significant decreases in the levels of triiodothyronine (T3) in both the F0 adults and F1 embryos, but thyroxine (T4) was not significantly affected. Additionally, the activities of antioxidant defenses, including catalase (CAT) and superoxide dismutase (SOD), and the expression of glutathione (GSH) and malondialdehyde (MDA) were significantly altered in the F0 and F1 larvae at 120 hpf. The hypothalamic-pituitary-thyroid (HPT) axis, oxidative stress, and apoptosis-related gene transcription expression were also significantly affected in both generations. Taken together, these findings highlight the importance of considering maternal transfer in uranium risk assessments.

Incidentally Detected Metachronous Malignancy in Patients of Papillary Carcinoma of Thyroid Posthigh-Dose Radioiodine Therapy

Thyroid cancer is one of the most common endocrine cancers. The most common histological subtypes are papillary and follicular variants; these are "differentiated thyroid cancers" and are associated with an excellent prognosis. The exact mechanism of thyroid cancer is not known. Several genetic alterations and environmental factors are found to be associated with this cancer. Patients with differentiated thyroid cancer are treated with postoperative radioactive iodine (RAI) therapy to ablate residual thyroid tissue and metastatic micro-foci. It is thought that after RAI, there is an increased risk of secondary malignancies such as lung, renal, and stomach cancer and lymphomas. However, the risk of secondary malignancy is not clear. They may be associated with genetic syndromes, environmental factors, and radiation exposure. The secondary malignancy may be detected incidentally during follow-up or present with signs and symptoms of that malignancy. There is no direct association between second malignancy and radiation exposure in I-131 therapies. We present a case series of five patients treated with high doses of I-131 for the remnant. The patients developed metachronous malignancies later in life.

A biologically based computational model for the hypothalamic-pituitary-thyroid (HPT) axis in Xenopus laevis larvae

A biologically based computational model was developed to describe the hypothalamic-pituitary-thyroid (HPT) axis in developing Xenopus laevis larvae. The goal of this effort was to develop a tool that can be used to better understand mechanisms of thyroid hormone-mediated metamorphosis in X. laevis and predict organismal outcomes when those mechanisms are perturbed by chemical toxicants. In this report, we describe efforts to simulate the normal biology of control organisms. The structure of the model borrows from established models of HPT axis function in mammals. Additional features specific to X. laevis account for the effects of organism growth, growth of the thyroid gland, and developmental changes in regulation of thyroid stimulating hormone (TSH) by circulating thyroid hormones (THs). Calibration was achieved by simulating observed changes in stored and circulating levels of THs during a critical developmental window (Nieuwkoop and Faber stages 54-57) that encompasses widely used in vivo chemical testing protocols. The resulting model predicts that multiple homeostatic processes, operating in concert, can act to preserve circulating levels of THs despite profound impairments in TH synthesis. Represented in the model are several biochemical processes for which there are high-throughput in vitro chemical screening assays. By linking the HPT axis model to a toxicokinetic model of chemical uptake and distribution, it may be possible to use this vitro effects information to predict chemical effects in X. laevis larvae resulting from defined chemical exposures.

Microcystin-LR induced transgenerational effects of thyroid disruption in zebrafish offspring by endoplasmic reticulum stress-mediated thyroglobulin accumulation and apoptosis

MC-LR can interfere with thyroid function in fish, but the underlying mechanism is still unclear. Current study focuses to study the intergenerational inheritance of MC-LR-induced thyroid toxicity in zebrafish and in rat thyroid cells. In vivo experiments, adult female zebrafish (F0) were exposed to MC-LR (0, 5, and 25 μg/L) for 90 days and mated with male zebrafish without MC-LR exposure to generate F1 generation. F1 embryos were allowed to develop normally to 7 days post-fertilization (dpf) in clear water. In the F0 generation, MC-LR induced disturbance of the hypothalamic-pituitary-thyroid (HPT) axis, leading to a decrease in the production of thyroid hormones. Maternal MC-LR exposure also induced growth inhibition by altering thyroid hormones (THs) homeostasis and interfering with thyroid metabolism and development in F1 offspring. Mechanistically, MC-LR caused excessive accumulation of ROS and induced ER stress that further lead to activation of UPR in the F0 and F1 offspring of zebrafish. Interestingly, our findings suggested that MC-LR exposure hampered thyroglobulin turnover by triggering IRE1 and PERK pathway in zebrafish and FRTL-5 thyroid cells, thus disturbing the thyroid endocrine system and contributing to the thyroid toxicity from maternal to its F1 offspring of zebrafish. Particularly, inhibition of the IRE1 pathway by siRNA could alleviate thyroid development injury induced by MC-LR in FRTL-5 cells. In addition, MC-LR induced thyroid cell apoptosis by triggering ER stress. Taken together, our results demonstrated that maternal MC-LR exposure causes thyroid endocrine disruption by ER stress contributing to transgenerational effects in zebrafish offspring.

Perfluorohexanoic acid caused disruption of the hypothalamus-pituitary-thyroid axis in zebrafish larvae

Perfluorohexanoic acid (PFHxA) has been recognized as an alternative to the wide usage of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) in the fluoropolymer industry for years. PFHxA has been frequently detected in the environment due to its wide application. However, the ecological safety of PFHxA, especially its toxicological effects on aquatic organisms, remains obscure. In the present study, PFHxA at different concentrations (0, 0.48, 2.4, and 12 mg/L) was added to the culture medium for zebrafish embryo/larval exposure at 96 h postfertilization (hpf). Zebrafish larvae showed a slow body growth trend and changes in thyroid hormone levels (THs) upon PFHxA exposure, indicating the interference effect of PFHxA on fish larval development. Moreover, the transcription levels of genes related to the hypothalamic-pituitary-thyroid (HPT) axis were also analyzed. The gene expression level of thyroid hormone receptor β (trβ) was upregulated in a dose-dependent manner. Exposure to 0.48 mg/L PFHxA increased the expression levels of the thyrotrophic-releasing hormone (trh) and thyroid hormone receptor α (trα). Significant increases in corticotrophin-releasing hormone (crh) and transthyretin (ttr) gene expression were also observed when the zebrafish larvae were treated with 12 mg/L PFHxA, except iodothyronine deiodinases (dio1), which decreased obviously at that point. There were significant declines in the transcription of both thyroid-stimulating hormone β (tshβ) and uridinediphosphate-glucuronosyltransferase (ugt1ab) upon exposure to 2.4 mg/L PFHxA. In addition, PFHxA induced a dose-related inhibitory effect on the transcription of sodium/iodide symporter (nis). Finally, the thyroid status will be destroyed after exposure to PFHxA, thus leading to growth impairment in zebrafish larvae.

Long-term low-dose oxytetracycline potentially leads to neurobehavioural changes

Trace levels of oxytetracycline (OTC)-a veterinary antibiotic and feed additive-are widespread in the environment. Studies revealed that OTC potentially impairs thyroid function, which may affect neurobehaviour; however, the impact of exposure to environmental concentrations of OTC on adult neurobehaviour is unknown. In this study, the effects of OTC on zebrafish after 30-day exposure were investigated. The total swimming distance was significantly increased under vibration and light/dark stimulation, while time spent in the white area was prolonged during the black/white preference test, indicating that the zebrafish became bolder and more impulsive under low OTC exposure. Additionally, monoamine neurotransmitter (5-hydroxytryptamine, dopamine, norepinephrine) levels were decreased and gene expression of monoamine oxidase (mao) involved in neurotransmitter metabolism was upregulated at the transcription level after OTC exposure. Because triiodothyronine (T3) levels were enhanced following exposure to OTC, we speculated that T3 may mediate OTC damage to the nervous system. Our simulated molecular docking analysis showed that OTC combined with the sodium iodide cotransporter protein may result in excessive T3 synthesis. We further exposed zebrafish to T3, and they exhibited similar behaviour to the OTC exposure group. In conclusion, environmental OTC may activate monoamine oxidase and enhance the metabolism of monoaminergic neurotransmitters via T3, thereby inducing abnormal neurobehaviour.

Early Predictive Response to Multi-Tyrosine Kinase Inhibitors in Advanced Refractory Radioactive-Iodine Differentiated Thyroid Cancer: A New Challenge for [18F]FDG PET/CT

Differentiated thyroid cancer (DTC) represents the most common thyroid cancer histotype. Generally, it exhibits a good prognosis after conventional treatments; nevertheless, about 20% of patients can develop a local recurrence and/or distant metastasis. In one-third of advanced DTC, the metastatic lesions lose the ability to take up iodine and become radioactive iodine-refractory (RAI-R) DTC. In this set of patients, the possibility to perform localized treatments should always be taken into consideration before the initiation of systemic therapy. In the last decade, some multi-tyrosine kinase inhibitor (MKI) drugs were approved for advanced DTC, impacting on patient’s survival rate, but at the same time, these therapies have been associated with several adverse events. In this clinical context, the role of 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography ([¹⁸F]FDG PET/CT) in the early treatment response to these innovative therapies was investigated, in order to assess the potentiality of this diagnostic tool in the early recognition of non-responders, avoiding unnecessary therapy. Herein, we aimed to present a critical overview about the reliability of [¹⁸F]FDG PET/CT in the early predictive response to MKIs in advanced differentiated thyroid cancer.

The Association Between Radioiodine Refractory in Papillary Thyroid Carcinoma, Sodium/Iodide Symporter Expression, and BRAF V600E Mutation

Objective

To study the association between radioiodine refractory papillary thyroid carcinoma, sodium/iodide symporter (NIS) expression, and the BRAF ^V600E mutation.

Methods

A study was conducted on 30 radioiodine refractory papillary thyroid carcinoma patients and 30 radioiodine-avid papillary thyroid carcinoma patients. The expressions of sodium/iodide symporter and BRAF ^V600E mutated protein were determined by immunohistochemistry using formalin-fixed, paraffin-embedded tissue.

Results

The mutated BRAF ^V600E protein was identified in 26 radioiodine refractory papillary thyroid carcinoma subjects (86.7%) and 22 radioiodine-avid papillary thyroid carcinoma subjects (73.3%), with no significant difference between the 2 groups (P = 0.3). Sodium/iodide symporter expression was detected in 4 of 30 cases (13.3%) from the radioiodine-avid papillary thyroid carcinoma group but was negative for all radioiodine refractory cases. There was no association between sodium/iodide symporter expression and radioiodine refractory papillary thyroid carcinoma (P = 0.11). Cases with positive NIS expression were likely negative for BRAF ^V600E mutation (3/4; P = 0.02).

Conclusion

Papillary thyroid carcinomas with BRAF ^V600E mutation were more likely to be negative for NIS expression. BRAF ^V600E mutation and NIS expressions cannot be used to predict radioiodine sensitivity.

The flavonoid quercetin reduces cell migration and increases NIS and E-cadherin mRNA in the human thyroid cancer cell line BCPAP

Thyroid cancer is the most frequent cancer of the endocrine system. Most patients are treated with thyroidectomy followed by radioiodine therapy. However, in part of the patients, a reduction of the sodium-iodide symporter (NIS) occurs, rendering radioiodine therapy ineffective. Moreover, epithelial-mesenchymal transition (EMT) may occur, leading to more aggressive and invasive features. Herein, we evaluated the effect of the flavonoid quercetin on EMT and NIS expression in BCPAP, a papillary thyroid carcinoma cell line. BCPAP was treated with 100 μM quercetin for 24 h and cell viability, apoptosis, EMT markers and NIS were evaluated. Quercetin decreased cell viability by enhancing apoptosis. The flavonoid also reduced matrix metalloproteinase 9 and increased E-cadherin mRNA levels, inhibiting BCPAP adhesion and migration. Additionally, quercetin increased NIS expression and function. Thus, our results suggest that quercetin could be useful as adjuvant in thyroid cancer therapy, inducing apoptosis, reducing invasion and increasing the efficacy of radioiodine therapy.

Waterborne uranium causes toxic effect and thyroid disruption in zebrafish larvae

Uranium is a radioactive element that is widely present in aquatic environment. However, limited knowledge is available about the effect of uranium on thyroid system, which plays a key role in the development of animals. In this study, zebrafish embryos were exposed to different environmentally relevant concentrations of uranium (2, 20 and 100 μg/L) for 120 h. The bioaccumulation, developmental toxicities, changes of thyroid hormones (THs) and key genes related to the hypothalamic-pituitary-thyroid (HPT) axis in larvae were analyzed after exposure. Results showed that uranium could bioaccumulate in zebrafish larvae, with the bioconcentration factors ranging from 49.6 to 523. Consequently, significant developmental toxicities and changes in locomotor activities were observed with a concentration-dependent manner. The levels of triiodothyronine (T3) levels in larvae were substantially decreased, whereas those of thyroxine (T4) were increased in fish bodies. The levels of THs were regulated by the negative feedback loops through HPT axis related genes, most of which (NIS, Deio1, Deio2, TRα, TSHβ and UGT1ab) were significantly depressed after exposure to uranium. Our results suggest the potential toxicities and thyroid disruption of uranium on zebrafish, which would provide baseline data set for better understanding the impact of waterborne uranium on aquatic organisms and the associated mechanisms. This study also highlights the key role of thyroid disruption in the ecological risk assessment of uranium pollution.

Proteomic Profiles of Thyroid Gland and Gene Expression of the Hypothalamic-Pituitary-Thyroid Axis Are Modulated by Exposure to AgNPs during Prepubertal Rat Stages

Silver nanoparticles (AgNPs) have potent antimicrobial activity and, for this reason, are incorporated into a variety of products, raising concern about their potential risks and impacts on human health and the environment. The developmental period is highly dependent on thyroid hormones (THs), and puberty is a sensitive period, where changes in the hormonal environment may have permanent effects. We evaluated the hypothalamic-pituitary (HP)-thyroid axis after exposure to low doses of AgNPs using a validated protocol to assess pubertal development and thyroid function in immature male rats. For stimulatory events of the HP-thyroid axis, we observed an increase in the expression of Trh mRNA and serum triiodothyronine. Negative feedback reduced the hypothalamic expression of Dio2 mRNA and increased the expression of Thra1, Thra2, and Thrb2 mRNAs. In the pituitary, there was a reduced expression of Mct-8 mRNA and Dio2 mRNA. For peripheral T3-target tissues, a reduced expression of Mct-8 mRNA was observed in the heart and liver. An increased expression of Dio3 mRNA was observed in the heart and liver, and an increased expression of Thrb2 mRNA was observed in the liver. The quantitative proteomic profile of the thyroid gland indicated a reduction in cytoskeletal proteins (Cap1, Cav1, Lasp1, Marcks, and Tpm4; 1.875 μg AgNP/kg) and a reduction in the profile of chaperones (Hsp90aa1, Hsp90ab1, Hspa8, Hspa9, P4hb) and proteins that participate in the N-glycosylation process (Ddost, Rpn1 and Rpn2) (15 μg AgNP/kg). Exposure to low doses of AgNPs during the window of puberty development affects the regulation of the HP-thyroid axis with further consequences in thyroid gland physiology.

Low-dose effects on thyroid disruption in zebrafish by long-term exposure to oxytetracycline

As a feed additive in agriculture, the antibiotic oxytetracycline (OTC) has become widely distributed in the natural environment, leading to the exposure of many organisms to low doses of OTC. Although OTC is clinically contraindicated in children because of its multiple side effects, the effect of exposure to low doses of environmental OTC on children is unknown, particularly during development. In this study, we investigated the effects of OTC on the thyroid endocrine system in zebrafish, through determinations of the whole-body contents of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) by enzyme-linked immunosorbent assay, and analysis of the mRNA expression of regulatory genes involved in the hypothalamus-pituitary-thyroid (HPT) axis using quantitative real-time polymerase chain reaction. Zebrafish embryos were exposed to OTC at environmentally relevant concentrations from 2 h to 120 days post-fertilisation. After exposure to OTC at 1,000 and 5,000 ng/L, T3 contents were significantly enhanced (37.8% and 45.1%, respectively) and TSH contents were reduced (16% and 16.3%, respectively) compared with those in the controls. The OTC-driven increase in the transcription of genes involved in thyroid synthesis (tpo and nis) may be responsible for the altered T3 levels. These data indicate that OTC may cause thyroid dysfunction and lead to reduced TSH secretion owing to enhanced negative feedback control of the HPT axis. Meanwhile, a decrease in body length, weight, and BMI and an increase in heart rate were observed with increasing OTC exposure. In conclusion, our results indicate that long-term exposure to low concentrations of OTC may alter the transcription of key genes involved in the HPT axis, as well as T3 and TSH contents, thereby disrupting the thyroid system and affecting the growth and development of zebrafish.

Keratinocyte Growth Factor-1 Protects Radioiodine-Induced Salivary Gland Dysfunction in Mice

Background: Most patients with thyroid cancer suffer from salivary gland (SG) dysfunctions after radioiodine (RI) therapy. We investigated the effects of keratinocyte growth factor (KGF)-1 on RI-induced SG dysfunction in an animal model. Methods: Six C57BL/6 mice were assigned to each of the following groups: treatment naïve control group, RI group, and RI+KGF-1 group. Body and SG weights, salivary flow rates, salivary lag times and changes in 99mTc pertechnetate uptake and excretion were measured, and histologic changes were noted. Amylase activities and epidermal growth factor (EGF) concentrations in saliva were also measured. In addition, TUNEL assays were performed and apoptosis-related protein expressions were assessed. Results: RI-induced reductions in salivary flow rates and increases in salivary lag times observed in the RI group were not observed in RI+KGF-1 group. Mice in RI group had higher HIF1a levels than controls, but HIF1a levels in RI+KGF-1 group were similar to those in control group. Furthermore, mice in RI+KGF-1 group had more mucin stained acini and decreased periductal fibrosis than mice in RI group, and tissue remodeling of many salivary epithelial cells (AQP5) and endothelial cells (CD31) were observed in RI+KGF-1 group. Amylase activity and expression in saliva were greater in RI+KGF-1 group than in RI group, and fewer apoptotic cells were observed in RI+KGF-1 group. Furthermore, BCLxl (anti-apoptotic) expression was higher, and Bax (pro-apoptotic) expression was lower in RI+KGF-1 group than in RI group. Conclusions: Local delivery of KGF-1 might prevent RI-induced SG damage by reducing apoptosis.

Acrylamide induces a thyroid allostasis-adaptive response in prepubertal exposed rats

•

Acrylamide acts as endocrine disruptor for the thyroid gland function.

•

Acrylamide increases the transcript expression of proteins related to THs synthesis.

•

Exposure to acrylamide alters the hypothalamus-pituitary-thyroid axis homeostasis.

•

Acrylamide induces allostatic regulation of the hypothalamus-pituitary-thyroid axis.

Some endocrine-disrupting chemicals (EDCs) can affect the endocrine system through covalent interactions with specific sites, leading to deregulation of physiological homeostasis. The acrylamide (AA) present in some fried or baked foods is an example of an electrophile molecule that is able to form adducts with nucleophilic regions of nervous system proteins leading to neurological defects. A positive correlation between increased urinary AA metabolite concentration and reduced levels of thyroid hormones (TH) was described in adolescents and young adults. Thus, this study aimed to evaluate whether AA affects the physiology of the hypothalamus-pituitary-thyroid (HPT) axis and the possible repercussions in peripheral TH-target systems. For this, male Wistar rats were exposed to doses of 2.5 or 5.0 mg AA/Kg/day, based on the LOAEL (Lowest Observed Adverse Effect Level) during prepubertal development. The expression of molecular markers of HPT functionality was investigated in the hypothalamus, pituitary, thyroid, heart and liver, as well as the hormonal and lipid profiles in blood samples. Herein, we showed that AA acts as EDCs for thyroid gland function, increasing the transcript expression of several proteins related to TH synthesis and altering hypothalamus-pituitary-thyroid axis homeostasis, an effect evidenced by the higher levels of THs in the serum. Compensatory mechanisms were observed in TH-target tissues, such as an increase in Dio3 mRNA expression in the liver and a reduction in Mct8 transcript content in the hearts of AA-treated rats. Together, these results pointed out an allostatic regulation of the HPT axis induced by AA and suggest that chronic exposure to it, mainly associated with food consumption, might be related to the higher prevalence of thyroid dysfunctions.

TNFα-mediated activation of NF-κB downregulates sodium-iodide symporter expression in thyroid cells

The sodium-iodide symporter (NIS) mediates transport of iodide across the basolateral membrane of thyroid cells. NIS expression in thyroid cancer (TC) cells allows the use of radioactive iodine (RAI) as a diagnostic and therapeutic tool, being RAI therapy the systemic treatment of choice for metastatic disease. Still, a significant proportion of patients with advanced TC lose the ability to respond to RAI therapy and no effective alternative therapies are available. Defective NIS expression is the main reason for impaired iodide uptake in TC and NIS downregulation has been associated with several pathways linked to malignant transformation. NF-κB signaling is one of the pathways associated with TC. Interestingly, NIS expression can be negatively regulated by TNF-α, a bona fide activator of NF-κB with a central role in thyroid autoimmunity. This prompted us to clarify NF-kB’s role in this process. We confirmed that TNF-α leads to downregulation of TSH-induced NIS expression in non-neoplastic thyroid follicular cell-derived models. Notably, a similar effect was observed when NF-κB activation was triggered independently of ligand-receptor specificity, using phorbol-myristate-acetate (PMA). TNF-α and PMA downregulation of NIS expression was reverted when NF-κB-dependent transcription was blocked, demonstrating the requirement for NF-kB activity. Additionally, TNF-α and PMA were shown to have a negative impact on TSH-induced iodide uptake, consistent with the observed transcriptional downregulation of NIS. Our data support the involvement of NF-κB-directed transcription in the modulation of NIS expression, where up- or down-regulation of NIS depends on the combined output to NF-κB of several converging pathways. A better understanding of the mechanisms underlying NIS expression in the context of normal thyroid physiology may guide the development of pharmacological strategies to increase the efficiency of iodide uptake. Such strategies would be extremely useful in improving the response to RAI therapy in refractory-TC.

Embryonic exposure to soil samples from a gangue stacking area induces thyroid hormone disruption in zebrafish

The total accumulative stockpiles of gangue from long-term coal mining exceed 1 billion tons and occupy 182 square kilometers, and 50 million tons of additional gangue are generated per year in Shanxi, a major energy province in China. The objective of this study was to examine whether exposure to village soils affected by gangue stacking would disrupt thyroid hormone system homeostasis and eventually affect endocrine system and development, using zebrafish (Danio rerio) as a model organism. The zebrafish embryos were exposed to village soil leachates at 0, 1:9, 1:3 and 1:1 from 1 to 120 h postfertilization (hpf), and the sample caused a dose-dependent increase in the mortality and malformation rate, and decrease in the heart rate, hatching rate and body length of zebrafish larvae. Importantly, the soil leachate alleviated the whole-body triiodothyronine (T3) and thyroxine (T4) levels at higher concentrations, and altered the expression of the hypothalamic-pituitary-thyroid (HPT) axis-regulating genes crh, trh, tshβ, nis, tg, nkx2.1, pax8, hhex, ttr, dio1, dio2, ugt1ab, trα, and trβ and the PAH exposure-related genes ahr2 and cyp1a. These findings highlight the potential risk of thyroid hormone disruption and developmental toxicity from soil samples around coal gangue stacking areas.

Thyroid endocrine disruption effects of perfluoroalkyl phosphinic acids on zebrafish at early development

Perfluoroalkyl phosphinic acids (PFPiAs, including 6:6, 6:8 and 8:8 PFPiAs) are one kind of emerging perfluoroalkyl substances and usually used as leveling and wetting agents in household cleaning products and pesticide formulations. In this study, zebrafish embryos (6 h post-fertilization [hpf]) were exposed to 6:6, 6:8 and 8:8 PFPiAs individually (0.5, 5 and 50 nM) for 168 hpf. 8:8 PFPiA at 5 and 50 nM reduced the body length, while all treatments of 6:8 and 8:8 PFPiA depressed the heartbeat of the zebrafish larvae. 8:8 PFPiA at 50 nM distinctly enhanced the thyroxine (T4) and triiodothyronine (T3) contents. In a negative feedback mechanism, the three PFPiAs remarkably suppressed the genes responsible for THs regulation (corticotropin-releasing hormone, crh; thyroid stimulating hormone, tshβ), and 8:8 PFPiA displayed the strongest effect. In addition, 8:8 PFPiA significantly promoted the gene expressions corresponding to THs transport, metabolism and action (transthyretin, ttr; uridine diphosphate glucuronosyltransferase, ugt1ab; deiodinases, dio1 and dio2; thyroid hormone receptors, trα and trβ). As a result, 8:8 PFPiA displayed the strongest thyroid endocrine disrupting effect and significantly affected the growth of zebrafish larvae among the three PFPiAs in the present study.

Human Bone Marrow Mesenchymal Stem Cells Functionalized by Hybrid Baculovirus-Adeno-Associated Viral Vectors for Targeting Hypopharyngeal Carcinoma

Hypopharyngeal carcinoma is a common malignant tumor of the head and neck with a very poor prognosis; the median survival time for curatively treated patients was 17.2 months in India. However, cell-based gene therapy holds promise to improve patient outcomes. In this study, we investigated whether human bone marrow mesenchymal stem cells (BMSCs) possess potential homing capacity for hypopharyngeal carcinoma. To monitor the efficiency of BMSC transplantation therapy through reporter gene imaging, we employed a hybrid baculovirus vector containing the Luc-P2A-eGFP fusion or sodium iodide symporter (NIS) sequence under the control of the cytomegalovirus promoter. To enhance the transfection efficiency, baculovirus vectors (Bac-CMV-Luc-P2A-eGFP-ITR and Bac-CMV-NIS-ITR) were flanked by inverted terminal repeats (ITRs), which are key elements of adeno-associated viruses. The infection efficiency of Bac-CMV-Luc-P2A-eGFP-ITR in BMSCs was as high as 92.84 ± 1.14% with no obvious toxic effects at a multiplicity of infection of 400. Moreover, Bac-CMV-NIS-ITR-infected BMSCs showed highly efficient radioactive iodide (¹²⁵I) uptake; these high uptake levels were maintained for at least 2 h. Transwell migration assays further demonstrated the chemotaxis of BMSCs to hypopharyngeal carcinoma cells (FaDu cells) in vitro. BMSCs modified by firefly luciferase report gene or NIS were injected into nude mice with hypopharyngeal carcinoma, and changes in the localization of the BMSCs were successfully tracked with bioluminescent imaging and micro-single-photon emission computed tomography imaging. These data indicate the potential utility of BMSCs as a promising targeted-delivery vehicle for hypopharyngeal carcinoma gene therapy. Importantly, BMSCs may represent a promising targeting vector for general tumor radionuclide therapy.

The Human Sodium Iodide Symporter as a Reporter Gene for Studying Middle East Respiratory Syndrome Coronavirus Pathogenesis

Single photon emission computed tomography (SPECT) is frequently used in oncology and cardiology to evaluate disease progression and/or treatment efficacy. Such technology allows for real-time evaluation of disease progression and when applied to studying infectious diseases may provide insight into pathogenesis. Insertion of a SPECT-compatible reporter gene into a virus may provide insight into mechanisms of pathogenesis and viral tropism. The human sodium iodide symporter (hNIS), a SPECT and positron emission tomography reporter gene, was inserted into Middle East respiratory syndrome coronavirus (MERS-CoV), a recently emerged virus that can cause severe respiratory disease and death in afflicted humans to obtain a quantifiable and sensitive marker for viral replication to further MERS-CoV animal model development. The recombinant virus was evaluated for fitness, stability, and reporter gene functionality. The recombinant and parental viruses demonstrated equal fitness in terms of peak titer and replication kinetics, were stable for up to six in vitro passages, and were functional. Further in vivo evaluation indicated variable stability, but resolution limits hampered in vivo functional evaluation. These data support the further development of hNIS for monitoring infection in animal models of viral disease.IMPORTANCE Advanced medical imaging such as single photon emission computed tomography with computed tomography (SPECT/CT) enhances fields such as oncology and cardiology. Application of SPECT/CT, magnetic resonance imaging, and positron emission tomography to infectious disease may enhance pathogenesis studies and provide alternate biomarkers of disease progression. The experiments described in this article focus on insertion of a SPECT/CT-compatible reporter gene into MERS-CoV to demonstrate that a functional SPECT/CT reporter gene can be inserted into a virus.

Impact of Patient Age and Histological Type on Radioactive Iodine Avidity of Recurrent Lesions of Differentiated Thyroid Carcinoma

BACKGROUND

Age is a prognostic factor for recurrent differentiated thyroid carcinoma (DTC) and may be related to radioactive iodine (RAI) nonavidity. Indications for molecular-targeted drugs (MTDs) are currently limited to RAI-refractory DTC. Demonstrating refractoriness to RAI, mainly indicated by RAI nonavidity, may be a barrier to the introduction of MTDs for elderly patients. The present study was conducted to evaluate the impact of age and histological type on the RAI avidity of recurrent lesions of DTC.

METHODS

Two hundred fifty-eight patients (189 patients with classic papillary thyroid carcinoma [cPTC], 8 patients with follicular variant of papillary thyroid carcinoma, and 61 patients with follicular thyroid carcinoma), who underwent their first RAI whole-body scanning for recurrent DTC at our institution between 2004 and 2013, were retrospectively studied. Radioactive iodine uptake was determined by visible uptake by metastatic lesion(s) in a diagnostic RAI-whole-body scan.

RESULTS

The prevalence of RAI-avid lung metastases in cPTC indicated a significant, inverse correlation with age (<55 years, 36.2%; ≥55 years, 3%; P < 0.001). By contrast, for follicular thyroid carcinoma, the prevalence of RAI avidity was not influenced by age. Similar tendencies were observed for lymph node metastases.

CONCLUSIONS

Radioactive iodine avidity by metastatic lesions of cPTC in elderly patients, especially those older than 55 years, was seldom demonstrated. Adherence to a strategy of restricting MTD administration after confirmation of RAI refractoriness should be revisited for elderly patients. A strategy of omitting RAI treatment should be taken into account when considering age and histological type.

Environmentally relevant concentrations of mercury exposure alter thyroid hormone levels and gene expression in the hypothalamic-pituitary-thyroid axis of zebrafish larvae

Mercury (Hg) is one of the most toxic heavy metals that can cause severe damage to fish. Studies have demonstrated that Hg has a specific affinity for the endocrine system, but little is known about the effects of Hg on thyroid endocrine system in fish. In this study, zebrafish embryos were exposed to environmentally relevant concentrations of 1, 4, and 16 μg/L Hg²⁺ (added as HgCl₂) from 2 h post-fertilization (hpf) to 168 hpf. Thyroid hormone (TH) levels and mRNA expression levels of genes involved in the hypothalamus-pituitary-thyroid (HPT) axis were determined. The results showed that exposure to 16 μg/L Hg²⁺ increased the whole-body thyroxine (T4) and triiodothyronine (T3) levels. The transcription levels of corticotrophin releasing hormone (crh) and thyroid stimulating hormone (tshβ) were up-regulated by Hg²⁺ exposure. Analysis of the mRNA levels of genes related to thyroid development (hhex, nkx2.1, and pax8) and THs synthesis (nis and tg) revealed that exposure to higher Hg²⁺ concentrations markedly up-regulated hhex, nkx2.1, nis, and tg expression, while had no significant effect on the transcripts of pax8. For the transcription of two types of deiodinases (deio1 and deio2), deio1 showed no significant changes in all the treatments, whereas deio2 was significantly up-regulated in the 16 μg/L Hg²⁺ group. In addition, Hg²⁺ exposure up-regulated thyroid hormone receptor β (trβ) mRNA level, while the transcription of trα was not changed. Overall, our study indicated that environmentally relevant concentrations of Hg²⁺ exposure could alter TH levels and the transcription of related HPT-axis genes, disturbing the normal processes of TH metabolism.

Incidence of Second Malignancy in Patients with Papillary Thyroid Cancer from Surveillance, Epidemiology, and End Results 13 Dataset

Increased risk of second primary malignancy (SPM) in papillary thyroid cancer (PTC) has been reported. Here, we present the most updated incidence rates of second primary malignancy from original diagnosis of PTC by using the data from the Surveillance, Epidemiology, and End Results. In this cohort, 3,200 patients developed SPM, a substantially higher number than in the reference population of 2,749 with observed to expected ratio (O/E) of 1.16 (95% CI; 1.12–1.21). Bone and joint cancer had the highest O/E ratio of 4.26 (95% confidence interval [CI] 2.33–7.15) followed by salivary gland (O/E 4.15; 95% CI 2.76–6.0) and acute lymphocytic leukemia (O/E 3.98; 95% CI 2.12–6.8). Mean age at the diagnosis of SPM was 64.4 years old. Interestingly, incidence of colorectal cancer was lower in thyroid cancer survivors compared to general population (large intestine O/E 0.3; 95% CI 0.06–0.88, rectum O/E 0.6; 95% CI 0.41–0.85); however, this was not observed in patients who underwent radiation therapy. The incidence of SPM at all sites was higher during 2000–2012 compared to 1992–1999 (O/E 1.24 versus 1.10). Surprisingly, patients with micropapillary cancer had higher incidence of SPM than counterparts with a larger tumor in radiation group (O/E of 1.40 versus 1.15). O/E of all cancers were higher in males compared to females with O/E of 1.41 versus 1.17 during the period of 2000–2012. Diagnosis of PTC before age 50, especially at age 30–34, was associated with higher incidence of overall SPM (age 30–34; O/E 1.43; 95% CI; 1.19–1.71). Efficient monitoring strategies that include age at the time of thyroid cancer diagnosis, exposure to radiation, gender, and genetic susceptibility may successfully detect SPM earlier in the disease course. This is especially important given the excellent prognosis of the initial thyroid cancer itself.

Exposure to PFDoA causes disruption of the hypothalamus-pituitary-thyroid axis in zebrafish larvae

Perfluorododecanoic acid (PFDoA), a kind of perfluorinated carboxylic acid (PFCA) with 12 carbon atoms, has an extensive industrial utilization and is widespread in both wildlife and the water environment, and was reported to have the potential to cause a disruption in the thyroid hormone system homeostasis. In this study, zebrafish embryos/larvae were exposed to different concentrations of PFDoA (0, 0.24, 1.2, 6 mg/L) for 96 h post-fertilization (hpf). PFDoA exposure caused obvious growth restriction connected with the reduced thyroid hormones (THs) contents in zebrafish larvae, strengthening the interference effect on the growth of fish larvae. The transcriptional level of genes within the hypothalamic-pituitary-thyroid (HPT) axis was analyzed. The gene expression levels of thyrotropin-releasing hormone (trh) and corticotrophin-releasing hormone (crh) were upregulated upon exposure to 6 mg/L of PFDoA, and iodothyronine deiodinases (dio2) was upregulated in the 1.2 mg/L PFDoA group. The transcription of thyroglobulin (tg) and thyroid receptor (trβ) were significantly downregulated upon exposure to 1.2 mg/L and 6 mg/L of PFDoA. PFDoA could also decrease the levels of sodium/iodide symporter (nis) and transthyretin (ttr) gene expression in a concentration-dependent manner after exposure. A significant decrease in thyroid-stimulating hormoneβ (tshβ), uridinediphosphate-glucuronosyltransferase (ugt1ab) and thyroid receptor (trα) gene expression were observed at 6 mg/L PFDoA exposure. Upregulation and downregulation of iodothyronine deiodinases (dio1) gene expression were observed upon the treatment of 1.2 mg/L and 6 mg/L PFDoA, respectively. All the data demonstrated that gene expression in the HPT axis altered after different PFDoA treatment and the potential mechanisms of the disruption of thyroid status could occur at several steps in the process of synthesis, regulation, and action of thyroid hormones.

Epigenetic Modifications in Thyroid Cancer Cells Restore NIS and Radio-Iodine Uptake and Promote Cell Death

Epigenetic modifications have been identified as being responsible for the de-differentiation of thyroid tissue and its malignant transformation. Cell proliferation inhibitory effects of the pan-deacetylase inhibitors panobinostat, SAHA and Trichostatin A (TSA), the modulation of the sodium iodide symporter (NIS; SLC5A5), thyroid transcription factor 1 (TTF1), high mobility group A2 (HMGA2), and H19 and their putative targeting miRNAs have been evaluated in vitro. The cell viability was measured in five thyroid cancer cell lines (FTC133, TPC1, BCPAP, 8505C, C643) by real time cell analyzer xCELLigence. Expression of the above mentioned markers was performed by RT-qPCR and Western Blot. Radioiodine up-take was detected by Gamma Counter with I¹³¹. Cell viability decreased after treatment in all five cell lines. 10 nM panobinostat; 1 µM TSA or 10 µM SAHA caused a significant over-expression of NIS transcript in all five cell lines, whereas NIS protein was up-regulated in FTC133, BCPAP, and C643 cell lines only. Radioiodine up-take increased in FTC133 and C643 cells after 48 h of treatment with 10 nM panobinostat and 1 µM TSA. A significant down-regulation of the oncogene HMGA2 was detected in all five cell lines; except for TPC1 cells that were treated with 1 µM TSA. In accordance, hsa-let-7b-5p and hsa-let-7f-5p were stable or significantly over-expressed in all of the cell lines, except for TPC1 cells that were treated with 10 µM SAHA. TTF1 was significantly down-regulated in FTC133, BCPAP, and 8505C cells; whereas, TPC1 and C643 showed an up-regulated or stable expression. TTF1 was over-expressed in samples of human anaplastic thyroid cancer; whereas, it was down-regulated in follicular and undetectable in papillary thyroid cancer. H19 was over-expressed after 48 h treatment, except for BCPAP cells that were treated with panobinostat and SAHA. H19 was differently expressed in human anaplastic, follicular and papillary thyroid tumor samples. Deacetylase inhibitors reduced cell viability, restored NIS and H19, and suppressed the oncogenes HMGA2 and TTF1 in thyroid cancer cells.

"With a little help from my friends" - The role of microbiota in thyroid hormone metabolism and enterohepatic recycling

The gut microbiota is composed of over 1200 species of anaerobes and aerobes bacteria along with bacteriophages, viruses and fungal species. Increasing evidence indicates that the intestinal microbiota, beside digestive equilibrium, is also crucial for immunologic, hormonal and metabolic homeostasis. The intestinal microbiota interacts with distant organs by signals which may be part of the bacteria themselves or their metabolites. Dysbiosis has been observed in inflammatory or autoimmune disorders such as multiple sclerosis or type 1 diabetes as well as in obesity and type 2 diabetes. Functional thyroid disorders were associated with bacterial overgrowth and a different microbial composition. Although thyroid metabolism was apparently disregarded, the interference of microbiota on peripheral iodothyronine homeostasis is an intriguing issue. In this review we focused on the interactions of intestinal microbiota with thyroid-related micronutrients and with the metabolic steps of endogenous and exogenous iodothyronines.

Iodide Binding in Sodium-Coupled Cotransporters

Several apical iodide translocation pathways have been proposed for iodide efflux out of thyroid follicular cells, including a pathway mediated by the sodium-coupled monocarboxylate transporter 1 (SMCT1), which remains controversial. Herein, we evaluate structural and functional similarities between SMCT1 and the well-studied sodium-iodide symporter (NIS) that mediates the first step of iodide entry into the thyroid. Free-energy calculations using a force field with electronic polarizability verify the presence of a conserved iodide-binding pocket between the TM2, TM3, and TM7 segments in hNIS, where iodide is coordinated by Phe67, Gln72, Cys91, and Gln94. We demonstrate the mutation of residue Gly93 of hNIS to a larger amino acid expels the side chain of a critical tryptophan residue (Trp255) into the interior of the binding pocket, partially occluding the iodide binding site and reducing iodide affinity, which is consistent with previous reports associating mutation of this residue with iodide uptake deficiency and hypothyroidism. Furthermore, we find that the position of Trp255 in this hNIS mutant mirrors that of Trp253 in wild-type hSMCT1, where a threonine (Thr91) occupies the position homologous to that occupied by glycine in wild-type hNIS (Gly93). Correspondingly, mutation of Thr91 to glycine in hSMCT1 makes the pocket structure more like that of wild-type hNIS, increasing its iodide affinity. These results suggest that wild-type hSMCT1 in the inward-facing conformation may bind iodide only very weakly, which may have implications for its ability to transport iodide.

Urinary Iodine, Perchlorate, and Thiocyanate Concentrations in U.S. Lactating Women

BACKGROUND

Iodine is an essential micronutrient for thyroid hormone production. Adequate iodine intake and normal thyroid function are important during early development, and breastfed infants rely on maternal iodine excreted in breast milk for their iodine nutrition. The proportion of women in the United States of childbearing age with urinary iodine concentration (UIC) <50 μg/L has been increasing, and a subset of lactating women may have inadequate iodine intake. UIC may also be influenced by environmental exposure to perchlorate and thiocyanate, competitive inhibitors of iodine transport into thyroid, and lactating mammary glands. Data regarding UIC in U.S. lactating women are limited. To adequately assess the iodine sufficiency of lactating women and potential associations with environmental perchlorate and thiocyanate exposure, we conducted a multicenter, cross-sectional study of urinary iodine, perchlorate, and thiocyanate concentrations in healthy U.S. lactating women.

METHODS

Lactating women ≥18 years of age were recruited from three U.S. geographic regions: California, Massachusetts, and Ohio/Illinois from November 2008 to June 2016. Demographic information and multivitamin supplements use were obtained. Iodine, perchlorate, and thiocyanate levels were measured from spot urine samples. Correlations between urinary iodine, perchlorate, and thiocyanate levels were determined using Spearman's rank correlation. Multivariable regression models were used to assess predictors of urinary iodine, perchlorate, and thiocyanate levels, and UIC <100 μg/L.

RESULTS

A total of 376 subjects (≥125 from each geographic region) were included in the final analyses [mean (SD) age 31.1 (5.6) years, 37% white, 31% black, and 11% Hispanic]. Seventy-seven percent used multivitamin supplements, 5% reported active cigarette smoking, and 45% were exclusively breastfeeding. Median urinary iodine, perchlorate, and thiocyanate concentrations were 143 μg/L, 3.1 μg/L, and 514 μg/L, respectively. One-third of women had UIC <100 μg/L. Spot urinary iodine, perchlorate, and thiocyanate levels all significantly positively correlated to each other. No significant predictors of UIC, UIC <100 μg/L, or urinary perchlorate levels were identified. Smoking, race/ethnicity, and marital status were significant predictors of urinary thiocyanate levels.

CONCLUSION

Lactating women in three U.S. geographic regions are iodine sufficient with an overall median UIC of 143 μg/L. Given ubiquitous exposure to perchlorate and thiocyanate, adequate iodine nutrition should be emphasized, along with consideration to decrease these exposures in lactating women to protect developing infants.

Acute exposure to tris (2-butoxyethyl) phosphate (TBOEP) affects growth and development of embryo-larval zebrafish

Tris (2-butoxyethyl) phosphate (TBOEP), is used as a flame retardant worldwide. It is an additive in materials and can be easily discharged into the surrounding environment. There is evidence linking TBOEP exposure to abnormal development and growth in zebrafish embryos/larvae. Here, using zebrafish embryo as a model, we investigated toxicological effects on developing zebrafish (Danio rerio) caused by TBOEP at concentrations of 0, 20, 200, 1000, 2000μg/L starting from 2h post-fertilization (hpf). Our findings revealed that TBOEP exposure caused developmental toxicity, such as malformation, growth delay and decreased heart rate in zebrafish larvae. Correlation analysis indicated that inhibition of growth was possibly due to down-regulation of expression of genes related to the growth hormone/insulin-like growth factor (GH/IGF) axis. Furthermore, exposure to TBOEP significantly increased thyroxine (T4) and 3,5,3'-triiodothyronine (T3) in whole larvae. In addition, changed expression of genes involved in the hypothalamic-pituitary-thyroid (HPT) axis was observed, indicating that perturbation of HPT axis might be responsible for the developmental damage and growth delay induced by TBOEP. The present study provides a new set of evidence that exposure of embryo-larval zebrafish to TBOEP can cause perturbation of GH/IGF axis and HPT axis, which could result in developmental impairment and growth inhibition.

All-trans retinoic acid suppresses malignant characteristics of CD133-positive thyroid cancer stem cells and induces apoptosis

Recently, diagnoses of radioiodine-refractory differentiated thyroid cancer (RAI-R DTC) have become more common; prognosis is poor. It has been suggested that cancer stem cells account for radiotherapy resistance. By flow cytometry, different expression percents of CD133 and OCT4 in thyroid cancer cell lines were detected. By real-time quantitative PCR, different mRNA expression of CD133, OCT4, GLUT1, thyroglobulin (TG), thyroperoxidase (TPO) and sodium iodine symporter (NIS) was analyzed; the localization of CD133, OCT4, and NIS expression was examined using immunofluorescence confocal microscopy. Different expression of CD133, OCT4, and NIS in 21 human thyroid cancer and nodule tissues was investigated using immunohistochemistry. CD133-positive cells were isolated by magnetic sorting. Stronger colony formation ability of CD133-positive and weaker ability of CD133-negative cells in vivo were examined by colony formation. The effects of all-trans retinoic acid (ATRA) on CD133-positive cells in vivo were explored with Cell Counting Kit-8, colony formation, apoptosis, cell cycle, and ethynyl deoxyuridine assays. The ARO cell line and RAI-R DTC tissue specimens had more CD133-positive cells. NIS expression was significantly lower in RAI-R DTC tissue compared to radioiodine-sensitive DTC (RAI-DTC) tissue and specimens from patients with thyroid nodule. ATRA inhibited the stem cell characteristics of CD133-positive cells and induced CD133-positive cell differentiation to CD133-negative cells, and promoted CD133-positive cell apoptosis.

Transcriptional and Biochemical Alterations in Zebrafish Eleuthero-Embryos (Danio rerio) After Exposure to Synthetic Progestogen Dydrogesterone

Little information has so far been known on the effects of synthetic progestogen dydrogesterone (DDG) in organisms like fish. This study aimed to investigate the effects of DDG on the transcriptional and biochemical alterations in zebrafish eleuthero-embryos. Zebrafish eleuthero-embryos were analyzed for the transcriptional alterations by real-time quantitative PCR (RT-qPCR) and biochemical changes by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FITR) after 144 h exposure to DDG. The results of qPCR analysis showed that DDG exposure significantly suppressed the transcriptions of target genes involved in hypothalamic-pituitary-thyroid (HPT) axis, while it induced the expression of target genes mRNA belonging to hypothalamic-pituitary-gonad (HPG) axis. In addition, ATR-FTIR spectroscopy analysis showed that the biochemical alterations of protein, nucleic acid and lipid were observed following DDG treatment. The finding from this study suggests that DDG exposure could have potential multiple effects in fish.

3-Iodothyronamine Decreases Expression of Genes Involved in Iodide Metabolism in Mouse Thyroids and Inhibits Iodide Uptake in PCCL3 Thyrocytes

BACKGROUND

3-Iodothyronamine (3-T₁AM) is an endogenous decarboxylated thyroid hormone (TH) metabolite. Pharmacological doses of 3-T₁AM decrease heart rate, body temperature, and metabolic rate in rodents-effects that are contrary to classic TH excess. Furthermore, a single dose of 3-T₁AM was shown to suppress the hypothalamic-pituitary-thyroid (HPT) axis in rats. It was hypothesized that 3-T₁AM might play a role in the fine-tuning of TH action and might have a direct regulatory effect on the thyroid gland.

METHODS

This study tested whether repeated 3-T₁AM treatment interfered with thyroid function and the HPT axis in mice. Therefore, male C57BL/6 mice were intraperitoneally injected with 5 mg/kg of 3-T₁AM or vehicle daily for seven days. Additionally, the effects of 3-T₁AM on the differentiated rat thyrocyte cell line PCCL3 were analyzed.

RESULTS

Repeated administration of 3-T₁AM decreased thyroidal mRNA content of the sodium iodide symporter (Nis), thyroglobulin, and pendrin in mice. No interference with the HPT axis was observed, as determined by unaltered pituitary mRNA levels of triiodothyronine-responsive genes, including thyrotropin subunit β. Furthermore, 3-T₁AM treatment did not change transcript levels of hepatic triiodothyronine-responsive genes, such as deiodinase 1. In line with this, serum TH concentrations were not changed after the treatment period of seven days. In concordance with the in vivo findings, 3-T₁AM decreased the thyrotropin-dependent expression of Nis and functional iodide uptake in PCCL3 cells in vitro. Additionally, uptake and metabolism of 3-T₁AM by PCCL3 cells was observed, as well as 3-T₁AM-dependent changes in intracellular Ca²⁺ concentration that might be involved in mediating the reported effects.

CONCLUSIONS

In conclusion, 3-T₁AM application decreased expression of selected TH synthesis genes by acting directly on the thyroid gland, and it might therefore affect TH synthesis without involvement of the HPT axis.

Is there an association between thyroid function abnormalities and breast cancer?

OBJECTIVE

The aim of this study was to evaluate the association between thyroid function abnormalities and breast cancer and, in particular, the prognostic markers of breast cancer..

SUBJECTS AND METHODS

Baseline levels of thyrotropin, free triiodothyronine, free thyroxine and thyroid autoantibodies were measured in 97 women with primary breast cancer, 27 women with benign breast disease, and 4 women with atypical ductal hyperplasia. Their baseline levels were compared with those in 48 healthy women with a normal mammography in the last 2 years.

RESULTS

There were no significant associations between history of thyroid disease and breast cancer (p = 0.33). The mean baseline levels of triiodothyronine and thyrotropin did not differ significantly between the compared groups. The mean baseline levels of free thyroxine were found to be significantly higher in the breast cancer group, even after adjusting for thyroid replacement therapy. The presence of thyroid antibodies did not differ significantly between the compared groups. In a subgroup analysis, breast cancer cases with thyroid disease and particularly hypothyroidism had a significantly lower incidence of lymph node metastases compared with breast cancer cases without thyroid disease.

CONCLUSIONS

Our data confirmed the proliferative effect of thyroid hormones on breast cells, which had previously been shown in vitro. Additionally, thyroid disease and particularly hypothyroid function appeared to be associated with a lower incidence of lymph node metastases. Further studies to determine the prognostic role of thyroid hormones in breast cancer are warranted.

Thyroid malignant neoplasm-associated biomarkers as targets for oncolytic virotherapy

Biomarkers associated with thyroid malignant neoplasm (TMN) have been widely applied in clinical diagnosis and in research oncological programs. The identification of novel TMN biomarkers has greatly improved the efficacy of clinical diagnosis. A more accurate diagnosis may lead to better clinical outcomes and effective treatments. However, the major deficiency of conventional chemotherapy and radiotherapy is lack of specificity. Due to the macrokinetic interactions, adverse side effects will occur, including chemotherapy and radiotherapy resistance. Therefore, a new treatment is urgently needed. As an alternative approach, oncolytic virotherapy may represent an opportunity for treatment strategies that can more specifically target tumor cells. In most cases, viral entry requires the expression of specific receptors on the surface of the host cell. Currently, molecular virologists and gene therapists are working on engineering oncolytic viruses with altered tropism for the specific targeting of malignant cells. This review focuses on the strategy of biomarkers for the production of novel TMN oncolytic therapeutics, which may improve the specificity of targeting of tumor cells and limit adverse effects in patients.

Thyroid antagonists and thyroid indicators in U.S. pregnant women in the Vanguard Study of the National Children's Study

The sodium iodide-symporter (NIS) mediates uptake of iodide into thyroid follicular cells. This key step in thyroid hormone synthesis is inhibited by perchlorate, thiocyanate (SCN) and nitrate (NO3) anions. When these exposures occur during pregnancy the resulting decreases in thyroid hormones may adversely affect neurodevelopment of the human fetus. Our objectives were to describe and examine the relationship of these anions to the serum thyroid indicators, thyroid stimulating hormone (TSH) and free thyroxine (FT4), in third trimester women from the initial Vanguard Study of the National Children's Study (NCS); and to compare urine perchlorate results with those in pregnant women from the National Health and Nutritional Examination Survey (NHANES). Urinary perchlorate, SCN, NO3, and iodine, serum TSH, FT4, and cotinine were measured and a food frequency questionnaire (FFQ) was administered to pregnant women enrolled in the initial Vanguard Study. We used multiple regression models of FT4 and TSH that included perchlorate equivalent concentration (PEC, which estimates combined inhibitory effects of the anions perchlorate, SCN, and NO3 on the NIS). We used multiple regression to model predictors of each urinary anion, using FFQ results, drinking water source, season of year, smoking status, and demographic characteristics. Descriptive statistics were calculated for pregnant women in NHANES 2001-2012. The geometric mean (GM) for urinary perchlorate was 4.04µg/L, for TSH 1.46mIU/L, and the arithmetic mean for FT4 1.11ng/dL in 359 NCS women. In 330 women with completed FFQs, consumption of leafy greens, winter season, and Hispanic ethnicity were significant predictors of higher urinary perchlorate, which differed significantly by study site and primary drinking water source, and bottled water was associated with higher urinary perchlorate compared to filtered tap water. Leafy greens consumption was associated with higher urinary NO3 and higher urinary SCN. There was no association between urinary perchlorate or PEC and TSH or FT4, even for women with urinary iodine <100µg/L. GM urinary perchlorate concentrations in the full sample (n=494) of third trimester NCS women (4.03µg/L) were similar to pregnant women in NHANES (3.58µg/L).

MicroRNAs let7 expression in thyroid cancer: correlation with their deputed targets HMGA2 and SLC5A5

PURPOSE

Thyroid cancer (TC), the most common endocrine malignancy, increases its incidence worldwide. MicroRNAs have been shown to be abnormally expressed in tumors and could represent valid diagnostic markers for patients affected by TC. Our aim was to analyze the expression of tumorsuppressor hsa-let7b-5p and hsa-let7f-5p, together with their predicted targets SLC5A5 (NIS) and HMGA2, in papillary (PTC), follicular (FTC) and anaplastic (ATC).

METHODS

8 FTC, 14 PTC, 12 ATC and three normal thyroid tissue samples were analyzed for the expression of pre-let7b, hsa-let7b-5p and hsa-let7f-5p as SLC5A5 and HMGA2 by RT-qPCR. Data were analyzed by REST 2008.

RESULTS

FTC patients showed a significant down-regulation of hsa-let7b-5p and its precursor. hsa-let7f-5p was overexpressed, and SLC5A5 was strongly suppressed. HMGA2 was overexpressed, reflecting no correlation with its regulatory let7 miRNAs. PTC samples were characterized by up-regulation of hsa-let7b-5p, its precursor and hsa-let7f-5p. SLC5A5 was strongly suppressed in comparison with normal thyroid tissue. HMGA2 was overexpressed, as shown in FTC, also. ATC samples showed a similar miRNAs profile as PTC. In contrast with FTC and PTC, these patients showed a stable or up-regulated SLC5A5 and HMGA2.

CONCLUSIONS

Expression of HMGA2 is not correlated with the regulatory let7 miRNAs. Interestingly, SLC5A5 was down-regulated in FTC and PTC. Its expression could be modulated by hsa-let-7f-5p. ATC showed a loss of SLC5A5/hsa-let7f-5p correlation. SLC5A5, in ATC, needs further investigation to clarify the genetic/epigenetic mechanism altering its expression.

Exposure to2,2',4,4'-tetrabromodiphenyl ether (BDE-47) alters thyroid hormone levels and thyroid hormone-regulated gene transcription in manila clam Ruditapes philippinarum

Polybrominated diphenyl ethers (PBDEs) have the potential to disturb the thyroid endocrine system in vertebrates, but little is known about the disruptive effects of PBDEs on marine bivalves. In this study, we first examined the effects of BDE-47 exposure on growth of juvenile manila clams Ruditapes philippinarum. The result showed that 1.0 and 10 μg L(-1) BDE-47 had adverse effects on 14-d shell-length growth of juvenile clams. Then, one-year-old adult clams were exposed to 0, 0.1 and 1 μg L(-1) BDE-47 for 15 d. BDE-47 (1 μg L(-1)) exposure caused significant decreases of total T4 (thyroxine) by 40% and T3 (3,5,3'-triiodothyronine) by 75% concentrations in haemolymph of the clams. Transcription of genes involved in thyroid hormone synthesis and metabolism were also studied by quantitative RT-PCR. Gene expression levels of sodium iodide symporter (rp-NIS), iodothyronine deiodinase (rp-Deio) and thyroid peroxidase (rp-TPO) were increased in a dose-dependent manner at day 5 and day 10, while monocarboxylate transporter 8 (rp-Mct8) was downregulated at day 5, day 10 and day 15. The effect and preliminary mechanism observed in the present study were consistent with the results from previous studies on rodent and fish, implying that exposure to BDE-47 may pose threat to thyroid hormone homeostasis in bivalves through thyroid synthesis and metabolism pathways. This study may provide a first step towards understanding of the thyroid function disruptive effects of PBDEs on marine bivalves and the underlying mechanism across taxonomic groups and phyla.

Placental transfer of and infantile exposure to perchlorate

Fetuses and infants are vulnerable to perchlorate toxicity. We assessed fetal and infantile exposure to perchlorate in two Chinese cities (Nanchang and Tianjin). Perchlorate was widely found (82%-100%) in breast milk, dissolved infant formula, infants' urine, maternal and cord blood samples. Perchlorate levels in infants' urine (mean ± standard deviation: 22.4 ± 35.6 ng mL(-1)), breast milk (36.6 ± 48.1 ng mL(-1)), and cord blood (3.18 ± 3.83 ng mL(-1)) samples collected from Nanchang and Tianjin were approximately an order of magnitude higher than those reported for the U.S. Perchlorate concentrations in cord blood were comparable to that in maternal blood, indicating that perchlorate is transferred from mother to fetus through placenta. Among all infants providing urine samples, the average daily intake of perchlorate (DOSEU) was estimated to be 1.17 ± 1.57 μg kg(-1) bw d(-1), and 40% of these infants had DOSEU exceeding the RfD (0.7 μg kg(-1) bw d(-1)) recommended by U.S. EPA. However, approximately 70% of exclusively breast-fed infants had perchlorate exposure dose via breast milk exceeding the RfD. For breast-fed infants, breast milk was the overwhelmingly predominant exposure pathway; while infant formula and indoor dust ingestion were major perchlorate exposure sources for formula-fed infants. To our knowledge, this is the first report to assess the fetal and infantile exposure to perchlorate in China.

Fluoride caused thyroid endocrine disruption in male zebrafish (Danio rerio)

Excessive fluoride in natural water ecosystem has the potential to detrimentally affect thyroid endocrine system, but little is known of such effects or underlying mechanisms in fish. In the present study, we evaluated the effects of fluoride on growth performance, thyroid histopathology, thyroid hormone levels, and gene expressions in the HPT axis in male zebrafish (Danio rerio) exposed to different determined concentrations of 0.1, 0.9, 2.0 and 4.1 M of fluoride to investigate the effects of fluoride on thyroid endocrine system and the potential toxic mechanisms caused by fluoride. The results indicated that the growth of the male zebrafish used in the experiments was significantly inhibited, the thyroid microtrastructure was changed, and the levels of T3 and T4 were disturbed in fluoride-exposed male fish. In addition, the expressional profiles of genes in HPT axis displayed alteration. The expressions of all studied genes were significantly increased in all fluoride-exposed male fish after exposure for 45 days. The transcriptional levels of corticotrophin-releasing hormone (CRH), thyroid-stimulating hormone (TSH), thyroglobulin (TG), sodium iodide symporter (NIS), iodothyronine I (DIO1), and thyroid hormone receptor alpha (TRα) were also elevated in all fluoride-exposed male fish after 90 days of exposure, while the inconsistent expressions were found in the mRNA of iodothyronineⅡ (DIO2), UDP glucuronosyltransferase 1 family a, b (UGT1ab), transthyretin (TTR), and thyroid hormone receptor beta (TRβ). These results demonstrated that fluoride could notably inhibit the growth of zebrafish, and significantly affect thyroid endocrine system by changing the microtrastructure of thyroid, altering thyroid hormone levels and endocrine-related gene expressions in male zebrafish. All above indicated that fluoride could pose a great threat to thyroid endocrine system, thus detrimentally affected the normal function of thyroid of male zebrafish.

Microcystin-RR exposure results in growth impairment by disrupting thyroid endocrine in zebrafish larvae

Recent studies have shown that cyanobacteria-derived microcystins (MCs) have the potential to disrupt endocrine systems. However, the effects of microcystin-RR (MC-RR) and their underlying mechanisms are poorly resolved in fish. In this study, MC-RR exposure through submersion caused serious developmental toxicity, such as growth delay and depressed heart rates in zebrafish larvae. We also detected decreased levels of thyroid hormones (THs), suggesting that MC-RR-triggered thyroid endocrine disruption might contribute to the growth impairment observed in developing zebrafish. To further our understanding of mechanisms of MC-RR-induced endocrine toxicity, quantitative real-time PCR (QPCR) analysis was performed on hypothalamic-pituitary-thyroid (HPT) axis related genes, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid receptors (TRα and TRβ) and iodothyronine deiodinases (Dio1 and Dio2), of developing zebrafish embryos exposed to 0, 0.3, 1.0 or 3.0mgL(-1) MC-RR until 96h post-fertilization. Our results showed that transcription pattern of HPT axis related genes were greatly changed by MC-RR exposure, except TG gene. Furthermore, western blot was used to validate the results of gene expression. The results showed protein synthesis of TG was not affected, while that of NIS was significantly up-regulated, which are in accordance with gene expression. The overall results indicated that exposure to MC-RR can induce developmental toxicity, which might be associated with thyroid endocrine disruption in developing zebrafish larvae.

Increased risk of second primary malignancy in pediatric and young adult patients treated with radioactive iodine for differentiated thyroid cancer

INTRODUCTION

The long-term sequelae of radioactive iodine (RAI) for differentiated thyroid cancer (DTC) in pediatric and young adult patients are not well-defined. Epidemiologic analyses of second primary malignancy (SPM) risk have only been performed in the adult population. Existing data are limited to case series with limited follow-up. The objective of this study was to analyze the elevated risk of SPM attributable to RAI in young patients treated for DTC.

METHODS

Population-based analysis of 3850 pediatric and young adult patients (<25 years old) undergoing treatment with surgery with/without RAI for DTC, followed in the Surveillance, Epidemiology, and End Results cancer registry (1973-2008), equating to 54,727 person-years at risk (PYR). The excess risk of SPM was calculated relative to a reference population and expressed as standardized incidence ratio (SIR) and excess absolute risk (EAR) per 10,000 PYR. Excess risk was compared in RAI-treated and non-RAI-treated patients.

RESULTS

A total of 1571 patients (40%) received RAI. The percentage of patients treated with RAI increased over time, from 4% in 1973 to 62% in 2008 (p<0.001). Among patients who received RAI, 26 SPMs were observed, and 18.3 were expected. The relative risk of SPM at any site was significantly elevated (SIR=1.42), corresponding to 4.4 excess cases per 10,000 PYR. SPM risk was not elevated in the non-RAI-treated cohort (SIR=1.01, EAR=0). Patients treated with RAI were at dramatically elevated risk for development of a salivary malignancy (SIR=34.1), corresponding to 1.7 excess cases per 10,000 PYR. The risk of leukemia in RAI-treated patients was elevated (SIR=4.0, EAR=0.9) but did not reach statistical significance. There was no elevated risk of salivary cancer or leukemia in the non-RAI-treated cohort.

CONCLUSIONS

Pediatric and young adult patients who receive RAI for DTC experience an elevated risk of SPM, mainly salivary gland cancer. These risks appear to be only slightly higher than in adult patients. Over a decade, approximately 1 in 227 RAI-treated patients will develop an SPM, and 1 in 588 RAI-treated patients will develop a salivary cancer, attributable to RAI. Because the expected survival time for young DTC patients is long, it is critical to weigh the benefits of RAI carefully against the small, but real, increase in SPM risk.

Iodide- and glucose-handling gene expression regulated by sorafenib or cabozantinib in papillary thyroid cancer

CONTEXT

The aberrant silencing of iodide-handling genes accompanied by up-regulation of glucose metabolism presents a major challenge for radioiodine treatment of papillary thyroid cancer (PTC).

OBJECTIVE

This study aimed to evaluate the effect of tyrosine kinase inhibitors on iodide-handling and glucose-handling gene expression in BHP 2-7 cells harboring RET/PTC1 rearrangement.

MAIN OUTCOME MEASURES

In this in vitro study, the effects of sorafenib or cabozantinib on cell growth, cycles, and apoptosis were investigated by cell proliferation assay, cell cycle analysis, and Annexin V-FITC apoptosis assay, respectively. The effect of both agents on signal transduction pathways was evaluated using the Western blot. Quantitative real-time PCR, Western blot, immunofluorescence, and radioisotope uptake assays were used to assess iodide-handling and glucose-handling gene expression.

RESULTS

Both compounds inhibited cell proliferation in a time-dependent and dose-dependent manner and caused cell cycle arrest in the G0/G1 phase. Sorafenib blocked RET, AKT, and ERK1/2 phosphorylation, whereas cabozantinib blocked RET and AKT phosphorylation. The restoration of iodide-handling gene expression and inhibition of glucose transporter 1 and 3 expression could be induced by either drug. The robust expression of sodium/iodide symporter induced by either agent was confirmed, and (125)I uptake was correspondingly enhanced. (18)F-fluorodeoxyglucose accumulation was significantly decreased after treatment by either sorafenib or cabozantinib.

CONCLUSIONS

Sorafenib and cabozantinib had marked effects on cell proliferation, cell cycle arrest, and signal transduction pathways in PTC cells harboring RET/PTC1 rearrangement. Both agents could be potentially used to enhance the expression of iodide-handling genes and inhibit the expression of glucose transporter genes.

Excess iodide induces an acute inhibition of the sodium/iodide symporter in thyroid male rat cells by increasing reactive oxygen species

Na+/I- symporter (NIS) mediates iodide (I-) uptake in the thyroid gland, the first and rate-limiting step in the biosynthesis of the thyroid hormones. The expression and function of NIS in thyroid cells is mainly regulated by TSH and by the intracellular concentration of I-. High doses of I- for 1 or 2 days inhibit the synthesis of thyroid hormones, a process known as the Wolff-Chaikoff effect. The cellular mechanisms responsible for this physiological response are mediated in part by the inhibition of I- uptake through a reduction of NIS expression. Here we show that inhibition of I- uptake occurs as early as 2 hours or 5 hours after exposure to excess I- in FRTL-5 cells and the rat thyroid gland, respectively. Inhibition of I- uptake was not due to reduced NIS expression or altered localization in thyroid cells. We observed that incubation of FRTL-5 cells with excess I- for 2 hours increased H2O2 generation. Furthermore, the inhibitory effect of excess I- on NIS-mediated I- transport could be recapitulated by H2O2 and reverted by reactive derived oxygen species scavengers. The data shown here support the notion that excess I- inhibits NIS at the cell surface at early times by means of a posttranslational mechanism that involves reactive derived oxygen species.

Cancer stratification by molecular imaging

The lack of specificity of traditional cytotoxic drugs has triggered the development of anticancer agents that selectively address specific molecular targets. An intrinsic property of these specialized drugs is their limited applicability for specific patient subgroups. Consequently, the generation of information about tumor characteristics is the key to exploit the potential of these drugs. Currently, cancer stratification relies on three approaches: Gene expression analysis and cancer proteomics, immunohistochemistry and molecular imaging. In order to enable the precise localization of functionally expressed targets, molecular imaging combines highly selective biomarkers and intense signal sources. Thus, cancer stratification and localization are performed simultaneously. Many cancer types are characterized by altered receptor expression, such as somatostatin receptors, folate receptors or Her2 (human epidermal growth factor receptor 2). Similar correlations are also known for a multitude of transporters, such as glucose transporters, amino acid transporters or hNIS (human sodium iodide symporter), as well as cell specific proteins, such as the prostate specific membrane antigen, integrins, and CD20. This review provides a comprehensive description of the methods, targets and agents used in molecular imaging, to outline their application for cancer stratification. Emphasis is placed on radiotracers which are used to identify altered expression patterns of cancer associated markers.

Progesterone and norgestrel alter transcriptional expression of genes along the hypothalamic-pituitary-thyroid axis in zebrafish embryos-larvae

The aim of this study was to investigate the effects of progestins on the hypothalamic-pituitary-thyroid (HPT) axis in the early stage of zebrafish. Zebrafish embryos were exposed to progesterone (P4) or norgestrel (NGT) at 5, 50 and 100 ng L(-1) for 144 h post fertilization (hpf), and the transcriptional levels of target genes along the hypothalamic-pituitary-thyroid axis were determined daily. The results showed that P4 had only minor effects on the mRNA expression of thyroglobulin (Tg), iodothyronine deiodinase type Ι (Dio1) and thyroid hormone receptor β (Thrb) genes. Similarly, the effects of NGT on transcripts of thyrotropin-releasing hormone (Trh), Dio1, iodothyronine deiodinase type II (Dio2) and thyroid hormone receptor α (Thra) genes were generally low. In addition, NGT resulted in some alterations of Tg and Thrb transcripts at different time points. However, a strong induction of Nis mRNA by P4 and NGT was observed in zebrafish embryos-larvae. The overall results showed that besides Nis no effects on the hypothalamic-pituitary-thyroid (HPT) axis are observed following exposure to P4 and NGT, which imply that both P4 and NGT have potential effects on the thyroid endocrine system by inducing transcript of Nis gene during the early stage of zebrafish.

All-trans-retinoic acid promotes iodine uptake via up- regulating the sodium iodide symporter in medullary thyroid cancer stem cells

Recently, the main therapy of medullary thyroid cancer (MTC) is surgical, but by which way there is a poor prognosis with a mean survival of only 5 years. In some cases, some researchers found that it is the medullary thyroid cancer stem cells (MTCSCs) that cause metastasis and recurrence. This study aimed to eradicate MTCSCs through administration of all-trans-retinoic acid (ATRA). Here we demonstrate that MTCSCs possess stem- like properties in serum-free medium. The ABCG2, OCT4 and sodium iodide symporter (NIS) were changed by ATRA. Additionally, we found that ATRA can increase the expression of NIS in vivo. All the data suggested that ATRA could increase the iodine uptake of MTCSCs through NIS.

Molecular pathogenesis of spondylocheirodysplastic Ehlers-Danlos syndrome caused by mutant ZIP13 proteins

The zinc transporter protein ZIP13 plays critical roles in bone, tooth, and connective tissue development, and its dysfunction is responsible for the spondylocheirodysplastic form of Ehlers-Danlos syndrome (SCD-EDS, OMIM 612350). Here, we report the molecular pathogenic mechanism of SCD-EDS caused by two different mutant ZIP13 proteins found in human patients: ZIP13(G64D), in which Gly at amino acid position 64 is replaced by Asp, and ZIP13(ΔFLA), which contains a deletion of Phe-Leu-Ala. We demonstrated that both the ZIP13(G64D) and ZIP13(ΔFLA) protein levels are decreased by degradation via the valosin-containing protein (VCP)-linked ubiquitin proteasome pathway. The inhibition of degradation pathways rescued the protein expression levels, resulting in improved intracellular Zn homeostasis. Our findings uncover the pathogenic mechanisms elicited by mutant ZIP13 proteins. Further elucidation of these degradation processes may lead to novel therapeutic targets for SCD-EDS.

Expression of thyrotropin receptor, thyroglobulin, sodium-iodide symporter, and thyroperoxidase by fibrocytes depends on AIRE

CONTEXT

CD34(+) fibrocytes, bone marrow-derived progenitor cells, infiltrate orbital connective tissue in thyroid-associated ophthalmopathy, a manifestation of Graves' disease. In the orbit, they become CD34(+) fibroblasts and coexist with native CD34(-) fibroblasts. Fibrocytes have been shown to express TSH receptor and thyroglobulin.

OBJECTIVE

The objective of the study was to determine whether a broader repertoire of thyroid protein expression can be detected in fibrocytes and whether a common factor is responsible.

DESIGN/SETTING/PARTICIPANTS

Fibrocytes and fibroblasts were collected and analyzed from healthy individuals and those with Graves' disease in an academic clinical practice.

MAIN OUTCOME MEASURES

Real-time PCR, Western blot analysis, gene promoter analysis, cell transfections, and flow cytometric cell sorting were performed.

RESULTS

We detect two additional thyroid proteins expressed by fibrocytes, namely sodium-iodide symporter and thyroperoxidase. The autoimmune regulator (AIRE) protein appears necessary for this expression. AIRE expression in fibrocytes results from an active AIRE gene promoter and stable AIRE mRNA. Knocking down AIRE with a targeting small interfering RNA reduces the expression of these thyroid proteins in fibrocytes as well as the transcription factors paired box-8 and thyroid transcription factor-1. When compared with an unaffected first-degree relative, levels of these proteins are substantially reduced in fibrocytes from an individual with an inactivating AIRE mutation. Levels of AIRE and the thyroid proteins are lower in orbital fibroblasts from patients with thyroid-associated ophthalmopathy than in fibrocytes. However, when mixed fibroblast populations are sorted into pure CD34(+) and CD34(-) subsets, the levels of these proteins are dramatically increased selectively in CD34(+) fibroblasts.

CONCLUSIONS

Fibrocytes express four proteins, the aggregate expression of which was previously thought to be restricted to thyroid epithelium. These proteins represent the necessary molecular biosynthetic machinery necessary for thyroid hormone production. Our findings implicate AIRE in the promiscuous expression of thyroid proteins in fibrocytes.