The mammary gland iodide transporter is expressed during lactation and in breast cancer

Combined Vorinostat and Chloroquine Inhibit Sodium-Iodide Symporter Endocytosis and Enhance Radionuclide Uptake In Vivo

PURPOSE

Patients with aggressive thyroid cancer are frequently failed by the central therapy of ablative radioiodide (RAI) uptake, due to reduced plasma membrane (PM) localization of the sodium/iodide symporter (NIS). We aimed to understand how NIS is endocytosed away from the PM of human thyroid cancer cells, and whether this was druggable in vivo.

EXPERIMENTAL DESIGN

Informed by analysis of endocytic gene expression in patients with aggressive thyroid cancer, we used mutagenesis, NanoBiT interaction assays, cell surface biotinylation assays, RAI uptake, and NanoBRET to understand the mechanisms of NIS endocytosis in transformed cell lines and patient-derived human primary thyroid cells. Systemic drug responses were monitored via 99mTc pertechnetate gamma counting and gene expression in BALB/c mice.

RESULTS

We identified an acidic dipeptide within the NIS C-terminus that mediates binding to the σ2 subunit of the Adaptor Protein 2 (AP2) heterotetramer. We discovered that the FDA-approved drug chloroquine (CQ) modulates NIS accumulation at the PM in a functional manner that is AP2 dependent. In vivo, CQ treatment of BALB/c mice significantly enhanced thyroidal uptake of 99mTc pertechnetate in combination with the histone deacetylase (HDAC) inhibitor vorinostat/SAHA, accompanied by increased thyroidal NIS mRNA. Bioinformatic analyses validated the clinical relevance of AP2 genes with disease-free survival in RAI-treated DTC, enabling construction of an AP2 gene-related risk score classifier for predicting recurrence.

CONCLUSIONS

NIS internalization is specifically druggable in vivo. Our data, therefore, provide new translatable potential for improving RAI therapy using FDA-approved drugs in patients with aggressive thyroid cancer. See related commentary by Lechner and Brent, p. 1220.

Thyroid Hormone Changes Correlate to Combined Breast Cancer with Primary Thyroid Cancer

Background

Breast cancer and thyroid cancer are two prevalent malignancies in women, and a potential association between the two diseases has been suggested.

Methods

This retrospective case-control study was conducted involving 97 patients with breast cancer and thyroid cancer (BC-TC group) and 97 age-matched patients with breast cancer alone (BC group). Thyroid hormone levels, including triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid-stimulating hormone (TSH), were analyzed in healthy controls, BC patients, and BC-TC patients.

Results

BC-TC patients exhibited a higher rate of estrogen receptor (ER) and progesterone receptor (PR) positivity compared to BC patients. Serum T3 levels were significantly decreased in BC and BC-TC patients compared to healthy controls. However, there was no significant difference in T3 levels between BC and BC-TC patients. Serum TSH levels were significantly higher in BC-TC patients compared to BC patients.

Conclusion

ER positivity, PR positivity, and serum TSH levels greater than 4.45 mU/L were independent risk factors for primary thyroid cancer in breast cancer patients.

Iodine Metabolism and Thyroid Function During the Perinatal Period: Maternal-Neonatal Correlation and Effects of Topical Povidone-Iodine Skin Disinfectants

An adequate maternal iodine intake during pregnancy and lactation is essential for growth and mental development in fetuses and newborns. There are limited data on perinatal iodine metabolism in mothers and infants, as well as the effect of povidone-iodine (PVP-I) antiseptics used in cesarean delivery. The urinary iodine concentration (UIC), serum iodine, thyrotropin (TSH), free thyroxine (FT4), and breast milk iodine concentration (BMIC) were measured consecutively in a total of 327 mothers and 249 term-infants in two prospective studies. The maternal median UIC was 164 μg/L in the third trimester, increased to 256 μg/L at 44 h after birth, and then decreased to 116 μg/L 1 month later. The BMIC on the 4th and 32th postpartum days was 17.6 and 13.5 μg/100 g, respectively. In neonatal infants born to the mothers unexposed to PVP-I, the median UIC was 131 μg/L in the first voiding urine and increased to 272 μg/L on day 4 and then slightly decreased to 265 μg/L on day 28 suggesting sufficient iodine reserve at birth. PVP-I antiseptics containing 1 g of iodine for skin preparation at cesarean delivery transiently increased maternal serum iodine concentration (1.9-fold), UIC (7.8-fold) at 41 h after surgery and BMIC, while it had little effect on maternal TSH, FT4, and neonatal UIC, TSH, or FT4. The iodine status of pregnant women and their infants was adequate in this population; however, the UIC in lactating mothers at one postpartum month was low enough to suggest iodine deficiency or near iodine deficiency. Further studies are necessary.

The master role of polarized NIS expression in regulating iodine metabolism in the human body

Objective

The aim of this study was to investigate how polarized sodium iodide symporter (NIS) expression may regulate iodide metabolism in vivo.

Materials and methods

Polarized NIS expression was analyzed in tissues that accumulate iodide by the use of immunohistochemistry and polyclonal antibody against the C-terminal end of human NIS (hNIS).

Results

Iodide absorption in the human intestine occurs via NIS expressed in the apical membrane. Iodide is secreted into the lumen of the stomach and salivary glands via NIS expressed in the basolateral membrane and then circulates back from the small intestine to the bloodstream via NIS expressed in the apical membrane.

Conclusion

Polarized NIS expression in the human body regulates intestinal-bloodstream recirculation of iodide, perhaps prolonging the availability of iodide in the bloodstream. This leads to more efficient iodide trapping by the thyroid gland. Understanding the regulation and manipulating gastrointestinal iodide recirculation could increase radioiodine availability during theranostic NIS applications.

Structural insights into the mechanism of the sodium/iodide symporter

The sodium/iodide symporter (NIS) is the essential plasma membrane protein that mediates active iodide (I-) transport into the thyroid gland, the first step in the biosynthesis of the thyroid hormones-the master regulators of intermediary metabolism. NIS couples the inward translocation of I- against its electrochemical gradient to the inward transport of Na+ down its electrochemical gradient1,2. For nearly 50 years before its molecular identification3, NIS was the molecule at the centre of the single most effective internal radiation cancer therapy: radioiodide (131I-) treatment for thyroid cancer2. Mutations in NIS cause congenital hypothyroidism, which must be treated immediately after birth to prevent stunted growth and cognitive deficiency2. Here we report three structures of rat NIS, determined by single-particle cryo-electron microscopy: one with no substrates bound; one with two Na+ and one I- bound; and one with one Na+ and the oxyanion perrhenate bound. Structural analyses, functional characterization and computational studies show the substrate-binding sites and key residues for transport activity. Our results yield insights into how NIS selects, couples and translocates anions-thereby establishing a framework for understanding NIS function-and how it transports different substrates with different stoichiometries and releases substrates from its substrate-binding cavity into the cytosol.

Links between Breast and Thyroid Cancer: Hormones, Genetic Susceptibility and Medical Interventions

Breast and thyroid glands are two common sites of female malignancies. Since the late 19th century, physicians have found that the cancers in either thyroid or mammary gland might increase the risk of second primary cancers in the other site. From then on, many observational clinical studies have confirmed the hypothesis and more than one theory has been developed to explain the phenomenon. Since the two glands both have secretory functions and are regulated by the hypothalamic-pituitary axis, they may share some common oncogenic molecular pathways. However, other risks factors, including medical interventions and hormones, are also observed to play a role. This article aims to provide a comprehensive review of the associations between the two cancers. The putative mechanisms, such as hormone alteration, autoimmune attack, genetic predisposition and other life-related factors are reviewed and discussed. Medical interventions, such as chemotherapy and radiotherapy, can also increase the risk of second primary cancers. This review will provide novel insights into the research designs, clinical managements and treatments of thyroid and breast cancer patients.

Mechanisms of Sodium/Iodide Symporter-Mediated Mammary Gland Iodine Compensation during Lactation

This research aimed to investigate the compensation mechanism of iodine deficiency and excess in the mammary gland during lactation. Female rats were divided into the low iodine group (LI), the normal iodine group (NI), the 10-fold high iodine group (10HI) and the 50-fold high iodine group (50HI). We measured the iodine levels in the urine, blood, milk, and mammary gland. The protein expression of sodium/iodide symporter (NIS), DPAGT1, and valosin-containing protein (VCP) in the mammary gland was also studied. The 24-hour urinary iodine concentration, serum total iodine concentration, serum non-protein-bound iodine concentration, breast milk iodine concentration, and mammary gland iodine content in the 50HI group were significantly higher than those in the NI group (p < 0.05). Compared with the NI group, NIS expression in the 50HI group significantly decreased (p < 0.05). DAPGT1 expression was significantly higher in the LI group than in the NI group (p < 0.05). The expression level of VCP was significantly increased in the 10HI and 50HI groups. In conclusion, milk iodine concentration is positively correlated with iodine intake, and the lactating mammary gland regulates the glycosylation and degradation of NIS by regulating DPAGT1 and VCP, thus regulating milk iodine level. However, the mammary gland has a limited role in compensating for iodine deficiency and excess.

The Role of Iodine for Thyroid Function in Lactating Women and Infants

Iodine is a micronutrient needed for the production of thyroid hormones, which regulate metabolism, growth, and development. Iodine deficiency or excess may alter the thyroid hormone synthesis. The potential effects on infant development depend on the degree, timing, and duration of exposure. The iodine requirement is particularly high during infancy because of elevated thyroid hormone turnover. Breastfed infants rely on iodine provided by human milk, but the iodine concentration in breast milk is determined by the maternal iodine intake. Diets in many countries cannot provide sufficient iodine, and deficiency is prevented by iodine fortification of salt. However, the coverage of iodized salt varies between countries. Epidemiological data suggest large differences in the iodine intake in lactating women, infants, and toddlers worldwide, ranging from deficient to excessive intake. In this review, we provide an overview of the current knowledge and recent advances in the understanding of iodine nutrition and its association with thyroid function in lactating women, infants, and toddlers. We discuss risk factors for iodine malnutrition and the impact of targeted intervention strategies on these vulnerable population groups. We highlight the importance of appropriate definitions of optimal iodine nutrition and the need for more data assessing the risk of mild iodine deficiency for thyroid disorders during the first 2 years in life.

Targeting non-canonical pathways as a strategy to modulate the sodium iodide symporter

The sodium iodide symporter (NIS) functions to transport iodide and is critical for successful radioiodide ablation of cancer cells. Approaches to bolster NIS function and diminish recurrence post-radioiodide therapy are impeded by oncogenic pathways that suppress NIS, as well as the inherent complexity of NIS regulation. Here, we utilize NIS in high-throughput drug screening and undertake rigorous evaluation of lead compounds to identify and target key processes underpinning NIS function. We find that multiple proteostasis pathways, including proteasomal degradation and autophagy, are central to the cellular processing of NIS. Utilizing inhibitors targeting distinct molecular processes, we pinpoint combinatorial drug strategies giving robust >5-fold increases in radioiodide uptake. We also reveal significant dysregulation of core proteostasis genes in human tumors, identifying a 13-gene risk score classifier as an independent predictor of recurrence in radioiodide-treated patients. We thus propose and discuss a model for targetable steps of intracellular processing of NIS function.

Assessment and treatment of thyroid disorders in pregnancy and the postpartum period

Thyroid disorders are prevalent in pregnant women. Furthermore, thyroid hormone has a critical role in fetal development and thyroid dysfunction can adversely affect obstetric outcomes. Thus, the appropriate management of hyperthyroidism, most commonly caused by Graves disease, and hypothyroidism, which in iodine sufficient regions is most commonly caused by Hashimoto thyroiditis, in pregnancy is important for the health of both pregnant women and their offspring. Gestational transient thyrotoxicosis can also occur during pregnancy and should be differentiated from Graves disease. Effects of thyroid autoimmunity and subclinical hypothyroidism in pregnancy remain controversial. Iodine deficiency is the leading cause of hypothyroidism worldwide. Despite global efforts to eradicate iodine deficiency disorders, pregnant women remain at risk of iodine deficiency due to increased iodine requirements during gestation. The incidence of thyroid cancer is increasing worldwide, including in young adults. As such, the diagnosis of thyroid nodules or thyroid cancer during pregnancy is becoming more frequent. The evaluation and management of thyroid nodules and thyroid cancer in pregnancy pose a particular challenge. Postpartum thyroiditis can occur up to 1 year after delivery and must be differentiated from other forms of thyroid dysfunction, as treatment differs. This Review provides current evidence and recommendations for the evaluation and management of thyroid disorders in pregnancy and in the postpartum period.

An Intramolecular Ionic Interaction Linking Defective Sodium/Iodide Symporter Transport to the Plasma Membrane and Dyshormonogenic Congenital Hypothyroidism

Background: The sodium/iodide symporter (NIS) mediates active iodide accumulation in the thyroid follicular cell. Autosomal recessive iodide transport defect (ITD)-causing loss-of-function NIS variants lead to dyshormonogenic congenital hypothyroidism due to deficient iodide accumulation for thyroid hormonogenesis. Here, we aimed to identify, and if so to functionally characterize, novel ITD-causing NIS pathogenic variants in a patient diagnosed with severe dyshormonogenic congenital hypothyroidism due to a defect in iodide accumulation in the thyroid follicular cell, as suggested by nondetectable radioiodide accumulation in a normally located thyroid gland, as well as in salivary glands. Methods: The proposita NIS-coding SLC5A5 gene was sequenced using Sanger sequencing. In silico analysis and functional in vitro characterization of the novel NIS variants were performed. Results: Sanger sequencing revealed novel compound heterozygous SLC5A5 gene variants (c.970-3C>A and c.1106A>T, p.D369V). In silico analysis suggested that c.970-3C>A disrupts the canonical splice acceptor site located in intron 7. Splicing minigene reporter assay revealed that c.970-3C>A causes exon 8 skipping during NIS pre-mRNA splicing leading to the NIS pathogenic variant p.Y324Hfs*148. Moreover, in silico analysis indicated p.D369V as pathogenic. Functional in vitro studies demonstrated that p.D369V NIS does not mediate iodide accumulation, as p.D369V causes NIS to be retained in the endoplasmic reticulum. Mechanistically, we propose an intramolecular ionic interaction involving the β carboxyl group of D369 and the guanidinium group of R130, located in transmembrane segment 4. Of note, an Asp residue at position 369-which is highly conserved in SLC5A family members-is required for functional NIS expression at the plasma membrane. Conclusions: We uncovered a critical intramolecular interaction between R130 and D369 required for NIS maturation and plasma membrane expression. Moreover, we identified the first intronic variant causing aberrant NIS pre-mRNA splicing, thus expanding the mutational landscape in the SLC5A5 gene leading to dyshormonogenic congenital hypothyroidism.

Benign thyroid disease and the risk of breast cancer: An updated systematic review and meta-analysis

BACKGROUND

The correlation between benign thyroid disease (BTD) and breast cancer (BC) has long been discussed. However, the definite relationship and potential mechanism between them are still disputed. The current meta-analysis aimed at performing a comprehensive assessment of the relationship between different types of benign thyroid disease and the risk of breast cancer, furthermore, assessing whether benign thyroid disease exerts an influence on the aggressiveness of breast cancer.

METHOD

A systematic literature search (PubMed, Web of Science, MEDLINE, and Embase databases) identified studies to evaluate the correlation between BTD and BC risk. Data were analyzed using version 16.0 STATA software, including the odds ratio (OR) and its corresponding 95% confidence intervals (CIs). Publication bias and quality assessment were conducted for the included studies.

RESULT

Overall, 18 studies involving 422,384 patients with BTD were incorporated. The outcome showed that autoimmune thyroiditis (OR: 2.56, 95%CI: 1.95-3.37, I^{2 =} 0.0%, p=0.460), goiter (OR: 2.13, 95%CI: 1.19-3.79, I^{2 =} 80.6%, p=0.000), and Graves' disease (OR: 5.01, 95%CI: 1.49-16.82, I^{2 =} 0.0%, p=0.358) was connected with a higher risk of BC. Both hypothyroidism (OR: 0.82, 95%CI: 0.64-1.04, I^{2 =} 85.0%, p=0.000) and hyperthyroidism (OR: 1.07, 95%CI: 0.93-1.24, I^{2 =} 24.9%, p=0.206) had no significant association with the risk of BC. Additionally, the pooled analysis showed no apparent correlation between BTD and aggressiveness of BC. However, subgroup analysis indicated a positive relationship between BTD and aggressiveness of BC in the Europe subgroup (HR: 2.05, 95%CI: 1.32-3.17, I^{2 =} 86.4%, p=0.000).

CONCLUSION

Autoimmune thyroiditis, goiter, and Graves' disease are connected with an increased risk of BC. Furthermore, subgroup analysis suggested that BTD increases the aggressiveness of BC in the European population geographically. Nevertheless, further research is needed to prove these discoveries.

The Iodine Rush: Over- or Under-Iodination Risk in the Prophylactic Use of Iodine for Thyroid Blocking in the Event of a Nuclear Disaster

Iodine is an essential element for the production of thyroid hormones (THs). Both deficient and excess iodine intakes may precipitate in adverse thyroidal events. Radioactive iodine (RI) is a common byproduct of nuclear fission processes. During nuclear emergencies RI may be released in a plume, or cloud, contaminating the environment. If inhaled or ingested, it may lead to internal radiation exposure and the uptake of RI mainly by the thyroid gland that absorbs stable iodine (SI) and RI in the same way. A dose of radiation delivered to the thyroid gland is a main risk factor for the thyroid cancer development. The SI prophylaxis helps prevent childhood thyroid cancer. The thyroid gland saturation with prophylactic SI ingestion, reduces the internal exposure of the thyroid by blocking the uptake of RI and inhibiting iodide organification. However, negative impact of inadequate SI intake must be considered. We provide an overview on the recommended iodine intake and the impact of SI and RI on thyroid in children and adolescents, discussing the benefits and adverse effects of the prophylactic SI for thyroid blocking during a nuclear accident. The use of SI for protection against RI may be recommended in cases of radiological or nuclear emergencies, moreover the administration of iodine for prophylactic purposes should be cautious. Benefits and risks should also be considered according to age. Adverse effects from iodine administration cannot be excluded. Precise indications are mandatory to use the iodine for thyroid blocking. Due to this natural adaption mechanism it's possible to tolerate large doses of iodine without clinical effects, however, a prolonged assumption of the iodine when not needed can be dangerous and may precipitate in severe thyroidal and non-thyroidal negative effects.

Potassium Iodide Nanoparticles Enhance Radiotherapy against Breast Cancer by Exploiting the Sodium-Iodide Symporter

Iodine has shown promise in enhancing radiotherapy. However, conventional iodine compounds show fast clearance and low retention inside cancer cells, limiting their application as a radiosensitizer. Herein, we synthesize poly(maleic anhydride-alt-1-octadecene) coated KI nanoparticles (PMAO-KI NPs) and evaluate their potential for enhancing radiotherapy. Owing to the polymer coating, the KI core of PMAO-KI NPs is not instantly dissolved in aqueous solutions but slowly degraded, allowing for controlled release of iodide (I^-). I^- is transported into cells via the sodium iodide symporter (NIS), which is upregulated in breast cancer cells. Our results show that PMAO-KI NPs can enhance radiation-induced production of reactive oxygen species such as hydroxyl radicals. When tested in vitro with MCF-7 cells, PMAO-KI NPs promote radiation-induced DNA double-strand breaks and lipid peroxidation, causing a drop in cancer cell viability and reproductivity. When tested in MCF-7 bearing mice, PMAO-KI NPs show significant radiosensitizing effects, leading to complete tumor eradication in 80% of the treated animals without inducing additional toxicity. Overall, our strategy exploits electrolyte nanoparticles to deliver iodide into cancer cells through NIS, thus promoting radiotherapy against breast cancer.

Thyroid Gene Mutations in Pregnant and Breastfeeding Women Diagnosed With Transient Congenital Hypothyroidism: Implications for the Offspring's Health

Fetus and infants require appropriate thyroid hormone levels and iodine during pregnancy and lactation. Nature endorses the mother to supply thyroid hormones to the fetus and iodine to the lactating infant. Genetic variations on thyroid proteins that cause dyshormonogenic congenital hypothyroidism could in pregnant and breastfeeding women impair the delivery of thyroid hormones and iodine to the offspring. The review discusses maternal genetic variations in thyroid proteins that, in the context of pregnancy and/or breastfeeding, could trigger thyroid hormone deficiency or iodide transport defect that will affect the proper development of the offspring.

A case of the accumulation of 131-iodine in the mammary gland after remnant ablation for papillary thyroid carcinoma on lactating period

The accumulation of 131-iodine is known to occur in the extrathyroidal tissues, such as the salivary glands and the gastrointestinal tract during radioactive iodine therapy. It is considered to be due to the expression of sodium iodide symporter. A 36-year-old lactating female was treated for remnant ablation for papillary thyroid carcinoma (pT1bN1bM0 pStage I) on the condition that she refrained from breastfeeding and was separated from her child and was milked to promote the excretion of 131-iodine until the accumulation disappeared on scintigram imaging. Scintigram showed the decrease and disappearance of the 131-iodine accumulation and the external dose rate was measured and confirmed to have decreased on the day 7 and 14 after the treatment. In conclusion, remnant ablation may be available by milking and separation from the child for 7 to 14 days.

Lithium from breast-milk inhibits thyroid iodine uptake and hormone production, which are remedied by maternal iodine supplementation

BACKGROUND

Lithium is especially taken as a maintenance medication for Bipolar Disorder. In women with bipolar disorder, lithium is often effective during postpartum period, but breast-feeding for medicated mothers is controversial because of harmful effects for her child. At present, the biological mechanisms of lithium are not well-understood, affecting its usage and overall health implications.

PROCEDURE

We developed a rat lithium and breast-feeding model at human therapeutic levels to study the effects of lithium exposure through breast-milk on pups' thyroid function. Novel laser analytical spectroscopy, along with traditional blood and immunohistochemical tests, were applied to further investigate the mechanisms behind the thyroid dysfunction. Maternal iodine supplementation was evaluated as a therapeutic method to address the pups' thyroid dysfunction.

RESULTS

Pups exposed to lithium via breastmilk, even with the dam on a sub-therapeutic level, experienced weight gain, reduced blood thyroxine (T₄ ), and elevated blood urea nitrogen, indicating effects on thyroid and kidney function. We show that lithium inhibited iodine uptake by thyroid follicles, initiating a mechanism that reduced iodination of tyrosine, thyroglobulin cleavage, and thyroid hormone production. Importantly, infant thyroid function can be significantly improved by administering supplementary iodine to the medicated dam's diet during breast-feeding.

CONCLUSION

These results elucidate the mechanisms of lithium in thyroid function, provide valuable information on use postpartum, and suggest a clinically applicable remedy to side-effects. The results are particularly important for patients (and their infants) who respond well to lithium and need, or choose, to breast-feed.

The Iodide Transport Defect-Causing Y348D Mutation in the Na+/I- Symporter Renders the Protein Intrinsically Inactive and Impairs Its Targeting to the Plasma Membrane

Background: The sodium/iodide (Na⁺/I^-) symporter (NIS) mediates active transport of I^- into the thyroid gland. Mutations in the SLC5A5 gene, which encodes NIS, cause I^- transport defects (ITDs)-which, if left untreated, lead to congenital hypothyroidism and consequent cognitive and developmental deficiencies. The ITD-causing NIS mutation Y348D, located in transmembrane segment (TMS) 9, was reported in three Sudanese patients. Methods: We generated cDNAs coding for Y348D NIS and mutants with other hydrophilic and hydrophobic amino acid substitutions at position 348 and transfected them into cells. The activity of the resulting mutants was quantitated by radioiodide transport assays. NIS glycosylation was investigated by Western blotting after endoglycosidase H (Endo H) and PNGase-F glycosidase treatment. Subcellular localization of the mutant proteins was ascertained by flow cytometry analysis, cell surface biotinylation, and immunofluorescence. The intrinsic activity of Y348D was studied by measuring radioiodide transport in membrane vesicles prepared from Y348D-NIS-expressing cells. Our NIS homology models and molecular dynamics simulations were used to identify residues that interact with Y348 and investigate possible interactions between Y348 and the membrane. The sequences of several Slc5 family transporters were aligned, and a phylogenetic tree was generated in ClustalX. Results: Cells expressing Y348D NIS transport no I^-. Furthermore, Y348D NIS is only partially glycosylated, is retained intracellularly, and is intrinsically inactive. Hydrophilic residues other than Asp at position 348 also yield NIS proteins that fail to be targeted to the plasma membrane (PM), whereas hydrophobic residues at this position, which we show do not interact with the membrane, rescue PM targeting and function. Conclusions: Y348D NIS does not reach the PM and is intrinsically inactive. Hydrophobic amino acid substitutions at position 348, however, preserve NIS activity. Our findings are consistent with our homology model's prediction that Y348 should face the side opposite the TMS9 residues that coordinate Na⁺ and participate in Na⁺ transport, and with the notion that Y348 interacts only with hydrophobic residues. Hydrophilic or charged residues at position 348 have deleterious effects on NIS PM targeting and activity, whereas a hydrophobic residue at this position rescues NIS activity.

Characterization of Genetic Variants in the SLC5A5 Gene and Associations With Breast Milk Iodine Concentration in Lactating Women of African Descent: The NUPED Study

Background: The sodium iodide symporter is responsible for the transfer of iodine into breast milk and is encoded for by the SLC5A5 gene. The role of genetic variants in the SLC5A5 gene locus in relation to the transfer of iodine from plasma into breast milk in healthy lactating individuals has, to our knowledge, not been explored. Objective: To identify and characterize possible genetic variants of the SLC5A5 gene in women of African descent living in urban South Africa, and to study associations with breast milk iodine concentrations (BMIC) in lactating women. Methods: This study is affiliated to the Nutrition during Pregnancy and Early Development (NuPED) cohort study (n = 250 enrolled pregnant women). In a randomly selected sub-sample of 32 women, the SLC5A5 gene was sequenced to identify known and novel variants. Of the identified variants, genotyping of selected variants was performed in all pregnant women who gave consent for genetic analyses (n = 246), to determine the frequency of the variants in the study sample. Urinary iodine concentration (UIC) in spot urine samples and BMIC were measured to determine iodine status. Associations of SLC5A5 genetic variants with BMIC were studied in lactating women (n = 55). Results: We identified 27 variants from sequencing of gene exomes and 10 variants were selected for further study. There was a significant difference in BMIC between the genotypes of the rs775249401 variant (P = 0.042), with the homozygous GG group having lower BMIC [86.8 (54.9-167.9) μg/L] compared to the (A) allele carriers rs775249401(AG+AA) [143.9 (122.4-169.3) μg/L] (P = 0.042). Of the rs775249401(GG), 49% had UIC <100 μg/L and 61% had BMIC <100 μg/L. On the other hand, 60% of the rs775249401(AG+AA) carriers had UIC <100 μg/L, and none had a BMIC <100 μg/L. Conclusion: Our results suggest that A-allele carriers of rs775249401(AG+AA) are likely to have higher iodine transfer into breast milk compared to the homozygous GG counterparts. Thus, genetic variations in the SLC5A5 gene may play an important role in the transfer of iodine from plasma into breast milk and may partially explain inter-individual variability in BMIC.

The PDZ protein SCRIB regulates sodium/iodide symporter (NIS) expression at the basolateral plasma membrane

The sodium/iodide symporter (NIS) expresses at the basolateral plasma membrane of the thyroid follicular cell and mediates iodide accumulation required for normal thyroid hormonogenesis. Loss-of-function NIS variants cause congenital hypothyroidism due to impaired iodide accumulation in thyroid follicular cells underscoring the significance of NIS for thyroid physiology. Here we report novel findings derived from the thorough characterization of the nonsense NIS mutant p.R636* NIS-leading to a truncated protein missing the last eight amino acids-identified in twins with congenital hypothyroidism. R636* NIS is severely mislocalized into intracellular vesicular compartments due to the lack of a conserved carboxy-terminal type 1 PDZ-binding motif. As a result, R636* NIS is barely targeted to the plasma membrane and therefore iodide transport is reduced. Deletion of the PDZ-binding motif causes NIS accumulation into late endosomes and lysosomes. Using PDZ domain arrays, we revealed that the PDZ-domain containing protein SCRIB binds to the carboxy-terminus of NIS by a PDZ-PDZ interaction. Furthermore, in CRISPR/Cas9-based SCRIB deficient cells, NIS expression at the basolateral plasma membrane is compromised, leading to NIS localization into intracellular vesicular compartments. We conclude that the PDZ-binding motif is a plasma membrane retention signal that participates in the polarized expression of NIS by selectively interacting with the PDZ-domain containing protein SCRIB, thus retaining the transporter at the basolateral plasma membrane. Our data provide insights into the molecular mechanisms that regulate NIS expression at the plasma membrane, a topic of great interest in the thyroid cancer field considering the relevance of NIS-mediated radioactive iodide therapy for differentiated thyroid carcinoma.

Cryo-EM: A new dawn in thyroid biology

The thyroid gland accumulates the rare dietary element iodine and incorporates it into iodinated thyroid hormones, utilising several tightly regulated reactions and molecular mechanisms. Thyroid hormones are essential in vertebrates and play a central role in many biological processes, such as development, thermogenesis and growth. The control of these functions is exerted through the binding of hormones to nuclear thyroid hormone receptors that rule the transcription of numerous metabolic genes. Over the last 50 years, thyroid biology has been studied extensively at the cellular and organismal levels, revealing its multiple clinical implications, yet, a complete molecular understanding is still lacking. This includes the atomic structures of crucial pathway components that would be needed to elucidate molecular mechanisms. Here we review the currently known protein structures involved in thyroid hormone synthesis, regulation, transport, and actions. We also highlight targets for future investigations that will significantly benefit from recent advances in macromolecular structure determination by electron cryo-microscopy (cryo-EM). As an example, we demonstrate how cryo-EM was crucial to obtain the structure of the large thyroid hormone precursor protein, thyroglobulin. We discuss modern cryo-EM compared to other structure determination methods and how an integrated structural and cell biological approach will help filling the molecular knowledge gap in our understanding of thyroid hormone metabolism. Together with clinical, cellular and high-throughput 'omics' studies, atomic structures of thyroid components will provide an important framework to map disease mutations and to interpret and predict thyroid phenotypes.

A Novel SLC5A5 Variant Reveals the Crucial Role of Kinesin Light Chain 2 in Thyroid Hormonogenesis

CONTEXT

Iodide transport defect (ITD) (Online Mendelian Inheritance in Man No. 274400) is an uncommon cause of dyshormonogenic congenital hypothyroidism due to loss-of-function variants in the SLC5A5 gene, which encodes the sodium/iodide symporter (NIS), causing deficient iodide accumulation in thyroid follicular cells.

OBJECTIVE

This work aims to determine the molecular basis of a patient's ITD clinical phenotype.

METHODS

The propositus was diagnosed with dyshormonogenic congenital hypothyroidism with minimal 99mTc-pertechnetate accumulation in a eutopic thyroid gland. The propositus SLC5A5 gene was sequenced. Functional in vitro characterization of the novel NIS variant was performed.

RESULTS

Sanger sequencing revealed a novel homozygous missense p.G561E NIS variant. Mechanistically, the G561E substitution reduces iodide uptake, because targeting of G561E NIS to the plasma membrane is reduced. Biochemical analyses revealed that G561E impairs the recognition of an adjacent tryptophan-acidic motif by the kinesin-1 subunit kinesin light chain 2 (KLC2), interfering with NIS maturation beyond the endoplasmic reticulum, and reducing iodide accumulation. Structural bioinformatic analysis suggests that G561E shifts the equilibrium of the unstructured tryptophan-acidic motif toward a more structured conformation unrecognizable to KLC2. Consistently, knockdown of Klc2 causes defective NIS maturation and consequently decreases iodide accumulation in rat thyroid cells. Morpholino knockdown of klc2 reduces thyroid hormone synthesis in zebrafish larvae leading to a hypothyroid state as revealed by expression profiling of key genes related to the hypothalamic-pituitary-thyroid axis.

CONCLUSION

We report a novel NIS pathogenic variant associated with dyshormonogenic congenital hypothyroidism. Detailed molecular characterization of G561E NIS uncovered the significance of KLC2 in thyroid physiology.

UFL1 regulates milk protein and fat synthesis-related gene expression of bovine mammary epithelial cells probably via the mTOR signaling pathway

UFL1 is an ufmylation (a novel post-translational modification) E3 ligase, mainly located in the endoplasmic reticulum (ER), that has emerged as a significant regulator of several physiological and pathological processes. Yet its physiological function in milk synthesis in bovine mammary epithelial cells (BMECs) remains unknown. In this study, we investigated the effects of UFL1 in milk protein and fat synthesis-related gene expression, with a particular emphasis on the role of UFL1 in LPS-treated BMECs. Results showed that UFL1 depletion significantly reduced the expression of milk protein and fat synthesis-related gene and mTOR phosphorylation in both normal and LPS-treated BMECs. Overexpression of UFL1 enhanced the activation of the mTOR and milk protein and fat synthesis-related gene expression. Collectively, these above results strongly demonstrate that UFL1 could regulate milk protein and fat synthesis-related gene expression of BMECs probably via the mTOR signaling pathway.

Causes of False-Positive Radioactive Iodine Uptake in Patients with Differentiated Thyroid Cancer

Purpose

Radioactive iodine (RAI) whole-body scan is a sensitive imaging modality routinely used in patients with differentiated thyroid cancer to detect persistent and recurrent disease. However, there can be false-positive RAI uptake that can lead to misdiagnosis and misclassification of a patient’s cancer stage. Recognizing the causes of false positivity can avoid unnecessary testing and treatment as well as emotional stress. In this review, we discuss causes and summarize various mechanisms for false-positive uptake.

Recent Findings

We report a patient with differentiated thyroid cancer who was found to have Mycobacterium avium complex infection as the cause of false-positive RAI uptake in the lungs. Using this case example, we discuss and summarize findings from the literature on etiologies of false-positive RAI uptake. We also supplement additional original images illustrating other examples of false RAI uptake.

Summary

False-positive RAI uptake may arise from different causes and RAI scans need to be interpreted in the context of the patient’s history and corresponding cross-sectional imaging findings on workup. Understanding the potential pitfalls of the RAI scan and the mechanisms underlying false uptake are vital in the care of patients with differentiated thyroid cancer.

Defending Effects of Iodide Transfer in Placental Barrier Against Maternal Iodine Deficiency

Objective: Placental iodide transport is necessary for maintaining an adequate iodide supply to the developing fetus. We hypothesized that compounds from the placental barrier can compensate for decreases in maternal iodine intake and normalize fetal iodine levels. Methods: Pregnant rats administered different amounts of iodine (1.24, 2.5, 5, or 10 μg/day) were evaluated on gestational day (gd) 16 and 20. The iodine levels in maternal blood, amniotic fluid (AF), and placental tissue were estimated using As-Ce catalytic spectrophotometry. The protein and/or messenger RNA (mRNA) levels of sodium iodide symporter (NIS), pendrin, alpha-smooth muscle actin (α-SMA), and CD31 in the placental labyrinth, trophoblast cells isolated using laser capture microdissection (LCM), and/or fetomaternal thyroid were detected using immunoblotting, real-time polymerase chain reaction, and/or immunohistochemistry. Results: When iodine intake was reduced, iodine levels in maternal blood gradually decreased; however, placental iodine levels were not significantly different between groups on gd16 and gd20. Minimal changes were observed in AF iodine levels on gd16, and a mild decreasing trend was observed (iodine dose, 10 to 1.24 μg/day) on gd20. NIS protein, which was linearly distributed along the basolateral membrane of maternal-fetal thyroid follicles, gradually increased with decreasing iodine levels. Regarding iodine deficiency in the placental labyrinth on gd16 and gd20, pendrin and glycosylated NIS proteins were significantly upregulated in a dose-dependent manner. However, the mRNA levels were unchanged. Furthermore, the conversion of NIS protein from the nonglycosylated to the glycosylated form increased. In trophoblast cells isolated using LCM, PDS mRNA levels increased in the 1.24-μg/day group on gd16 but not NIS mRNA levels. There was a smaller α-SMA+ area in the labyrinth zone on gd16 and gd20; however, the proportional CD31+ area increased on gd16 and reduced on gd20 with decreased iodine levels. Conclusions: All mechanisms upregulating the expression of iodine transporters and changes in villous stroma and microvessel area in the placental labyrinth can promote iodide transfer from mother to fetus in iodine deficiency, especially before the onset of fetal thyroid function. Compensatory NIS protein regulation in the placenta against decreased iodine intake mainly occurs during translation and glycosylation modification after translation. Pendrin may be more important than NIS in the mediation of placental iodide transport.

Radio-Iodide Treatment: From Molecular Aspects to the Clinical View

Simple Summary

This year marks the 80th commemoration of the first time that radio-iodide treatment (RAI) was used. RAI is one of the most effective targeted internal radiation anticancer therapies ever devised and it has been used for many decades, however, a thorough understanding of the underlying molecular mechanisms involved could greatly improve the success of this therapy. This is an in-depth innovative review focusing on the molecular mechanisms underlying radio-iodide therapy in thyroid cancer and how the alteration of these mechanisms affects the results in the clinic.

Abstract

Thyroid radio-iodide therapy (RAI) is one of the oldest known and used targeted therapies. In thyroid cancer, it has been used for more than eight decades and is still being used to improve thyroid tumor treatment to eliminate remnants after thyroid surgery, and tumor metastases. Knowledge at the molecular level of the genes/proteins involved in the process has led to improvements in therapy, both from the point of view of when, how much, and how to use the therapy according to tumor type. The effectiveness of this therapy has spread into other types of targeted therapies, and this has made sodium/iodide symporter (NIS) one of the favorite theragnostic tools. Here we focus on describing the molecular mechanisms involved in radio-iodide therapy and how the alteration of these mechanisms in thyroid tumor progression affects the diagnosis and results of therapy in the clinic. We analyze basic questions when facing treatment, such as: (1) how the incorporation of radioiodine in normal, tumor, and metastatic thyroid cells occurs and how it is regulated; (2) the pros and cons of thyroid hormonal deprivation vs. recombinant human Thyroid Stimulating Hormone (rhTSH) in radioiodine residence time, treatment efficacy, thyroglobulin levels and organification, and its influence on diagnostic imaging tests and metastasis treatment; and (3) the effect of stunning and the possible causes. We discuss the possible incorporation of massive sequencing data into clinical practice, and we conclude with a socioeconomical and clinical vision of the above aspects.

In vitro assays for characterization of distinct multiple catalytic activities of thyroid peroxidase using LC-MS/MS

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Multiple reactions catalyzed by thyroid peroxidase (TPO) were monitored by a battery of unique in vitro assays.

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Monoiodination and diiodination of L-Tyr to MIT and DIT was examined in a single assay.

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MIT to DIT and T3 to T4 monoiodination reactions were monitored separately.

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DIT to T4 conversion assay was used to study coupling of iodotyrosine phenolic rings.

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Distinct Km, Vmax, Kcat and Kcat/ Km values for each of the TPO catalysed reaction are presented.

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Differential response of 5 known inhibitors with specific TPO reactions was studied.

A diverse set of environmental contaminants have raised a concern about their potential adverse effects on endocrine signaling. Robust and widely accepted battery of in vitro assays is available to assess the disruption of androgenic and estrogenic pathways. However, such definitive systems to investigate effects on the disruption of thyroid pathways by the xenobiotics are not yet well established. One of the major “Molecular Initiating Events” (MIEs) in thyroid disruption involves targeting of thyroid peroxidase (TPO), a key enzyme involved in thyroid hormone synthesis. TPO catalyzes mono- and diiodination of L-Tyrosine (L-Tyr) to generate 3-Iodo-l-tyrosine (MIT) and 3,5-Diiodo-l-tyrosine (DIT), respectively, followed by the coupling of iodinated tyrosine rings to generate thyroid hormones, 3,3’5-Triiodo-l-thyronine (T3) and Levothyroxine (T4).

We sought to develop a robust, sensitive, and rapid in vitro assay systems to evaluate the effects of test chemicals on the multiple catalytic activities of thyroid peroxidase. Simple in vitro assays were designed to study TPO mediated distinct reactions using a single LC-MS/MS method.

Herein, we describe a battery of assays to investigate the iodination of L-Tyr to MIT and DIT, MIT to DIT as well as, T3 to T4 catalyzed by rat thyroid TPO. Importantly, two sequential reactions involving mono- and diiodination of L-Tyr could be analyzed in a single assay. The assay that monitors in vitro conversion of DIT to T4 was developed to study the coupling of tyrosine rings. Enzyme kinetics studies revealed distinct characteristics of multiple reactions catalyzed by TPO. Further, the known TPO inhibitors were used to assess their potency towards individual TPO substrates and reactions. The resultant half maximum inhibitory concentration (IC₅₀) values highlighted differential targeting of TPO catalyzed reactions by the same inhibitor. Overall results underscore the need to develop more nuanced approaches that account for distinct multiple catalytic activities of TPO.

Tumor microenvironment affects exogenous sodium/iodide symporter expression

For decades, sodium/iodide symporter NIS-mediated iodide uptake has played a crucial role in the radioactive ablation of thyroid cancer cells. NIS-based gene therapy has also become a promising tool for the treatment of tumors of extrathyroidal origin. But its applicability has been hampered by reduced expression of NIS, resulting in a moderated capacity to accumulate 131I and in inefficient ablation. Despite numerous preclinical enhancement strategies, the understanding of NIS expression within tumors remains limited. This study aims at a better understanding of the functional behavior of exogenous NIS expression in the context of malignant solid tumors that are characterized by rapid growth with an insufficient vasculature, leading to hypoxia and quiescence. Using subcutaneous HT29NIS and K7M2NIS tumors, we show that NIS-mediated uptake and NIS expression at the plasma membrane of cancer cells are impaired in the intratumoral regions. For a better understanding of the underlying molecular mechanisms induced by hypoxia and quiescence (separately and in combination), we performed experiments on HT29NIS cancer cells. Hypoxia and quiescence were both found to impair NIS-mediated uptake through mechanisms including NIS mis-localization. Modifications in the expression of proteins and metabolites involved in plasma membrane localization and in energy metabolism were found using untargeted proteomics and metabolomics approaches. In conclusion, our results provide evidence that hypoxia and quiescence impair NIS expression at the plasma membrane, and iodide uptake. Our study also shows that the tumor microenvironment is an important parameter for successful NIS-based cancer treatment.

Expression of the sodium iodide symporter (NIS) in reproductive and neural tissues of teleost fish

Iodine, an essential component of thyroid hormones, can only be obtained through the diet. The sodium iodide symporter (NIS) transports iodide across mammalian intestinal and thyroid epithelia to deliver iodide for thyroid hormone production. Using reverse transcription-polymerase chain reaction (RT-PCR) we confirmed that mRNA for a homolog of mammalian NIS is expressed in comparable locations, both sub-pharyngeal thyroid tissue and intestine, in multiple teleost fish species, supporting a conserved mechanism for intestinal-thyroid iodine transport across vertebrates. To determine when in embryogenesis NIS expression is initiated we utilized in situ hybridization (ISH) during development of zebrafish (Danio rerio) embryos. This revealed expression of nis as early as 2 days post fertilization (dpf) along the dorsal surface of the yolk sac, suggesting a function to import iodine from yolk. To evaluate the potential for maternal deposition of iodine in yolk, RT-PCR and further in situ staining of ovarian tissue in gravid female zebrafish confirmed NIS mRNA presence in the ooplasm and granulosa layer of early stage follicles. This further suggests that maternally-deposited NIS mRNA may be available for early embryogenesis. Unexpectedly, ISH in embryos revealed robust nis expression in the central nervous system throughout days 2-5 days post fertilization, with adult whole brain ISH localizing expression in the hypothalamus, cerebellum, and optic tectum. RT-PCR on whole brain tissue from five species of adult fish representing three taxonomic orders likewise revealed robust CNS expression. These unexpected locations of nis expression suggest novel, as yet undescribed reproductive and neural functions of NIS in teleost species.

Low Basal CB2R in Dopamine Neurons and Microglia Influences Cannabinoid Tetrad Effects

There are two well-characterized cannabinoid receptors (CB1R and CB2R and other candidates): the central nervous system (CNS) enriched CB1R and peripheral tissue enriched CB2R with a wide dynamic range of expression levels in different cell types of human tissues. Hepatocytes and neurons express low baseline CB1R and CB2R, respectively, and their cell-type-specific functions are not well defined. Here we report inducible expression of CB1R in the liver by high-fat and high sugar diet and CB2R in cortical neurons by methamphetamine. While there is less controversy about hepatocyte CB1R, the presence of functional neuronal CB2R is still debated to date. We found that neuron CB2R basal expression was higher than that of hepatocyte CB1R by measuring mRNA levels of specific isoform CB2A in neurons isolated by fluorescence-activated cell sorting (FACS) and CB1A in hepatocytes isolated by collagenase perfusion of liver. For in vivo studies, we generated hepatocyte, dopaminergic neuron, and microglia-specific conditional knockout mice (Abl-Cnr1Δ, Dat-Cnr2Δ, and Cx3cr1-Cnr2Δ) of CB1R and CB2R by crossing Cnr1f/f and Cnr2f/f strains to Abl-Cre, Dat-Cre, and Cx3cr1-Cre deleter mouse strains, respectively. Our data reveals that neuron and microglia CB2Rs are involved in the "tetrad" effects of the mixed agonist WIN 55212-2, CB1R selective agonist arachidonyl-2'-chloroethylamide (ACEA), and CB2R selective agonist JWH133. Dat-Cnr2Δ and Cx3cr1-Cnr2Δ mice showed genotypic differences in hypomobility, hypothermia, analgesia, and catalepsy induced by the synthetic cannabinoids. Alcohol conditioned place preference was abolished in DAT-Cnr2Δ mice and remained intact in Cx3cr1-Cnr2Δ mice in comparison to WT mice. These Cre-loxP recombinant mouse lines provide unique approaches in cannabinoid research for dissecting the complex endocannabinoid system that is implicated in many chronic disorders.

FOXA1 Regulation Turns Benzamide HDACi Treatment Effect-Specific in BC, Promoting NIS Gene-Mediated Targeted Radioiodine Therapy

Human sodium iodide symporter (NIS) gene mediated radio-ablation is a successful procedure in thyroid cancer clinics. In recent years, natural expression of NIS is reported in breast cancer (BC) cases but is yet to make its mark as a therapeutic procedure in BC clinics. A pre-exposure to histone deacetylase (HDAC) inhibitors to amplify endogenous NIS expression was attempted, but achieving cancer tissue-specific enhancement of NIS in patients is an important challenge to win. Here, for the first time, we show that a benzamide class of HDACi (bHDACi) can significantly induce NIS gene expression and function (p < 0.05) in BC cells with minimal off-target effects. Transcription factor (TF) profiler and promoter binding array reveals 22 TFs differentially activated by CI-994, of which FOXA1 is identified as a unique and positive regulator of NIS. Clonogenic assay shows reduced survival with bHDACi + ¹³¹I combination treatment. Further, AR-42 and MS-275 treatment shows enhanced NIS expression in an orthotopic breast tumor model. Combining bHDACi with 1 mCi ¹³¹I shows 40% drop in signal (p < 0.05), indicating enhanced radio-ablation effect. Cerenkov imaging revealed higher accumulation of ¹³¹I in MS-275-treated tumors. Thus, bHDACi-mediated selective enhancement ensuring minimal off-target effect is a step further toward using NIS as a therapeutic target for BC.

Perfluorooctane sulfonic acid, a persistent organic pollutant, inhibits iodide accumulation by thyroid follicular cells in vitro

Poly- and perfluoroalkyl substances (PFAS) are a class of endocrine disrupting chemicals (EDCs) reported to alter thyroid function. Iodide uptake by thyroid follicular cells, an early step in the synthesis of thyroid hormones, is a potential target for thyroid disruption by EDCs. The aim of the present study was to evaluate the acute effects of perfluorooctane sulfonic acid (PFOS) and perfluorooctane carboxylic acid (PFOA), two of the most abundant PFAS in the environment, on iodide transport by thyroid follicular cells in vitro. Dynamic changes in intracellular iodide concentration were monitored by live cell imaging using YFP-H148Q/I152, a genetically encoded fluorescent iodide biosensor. PFOS, but not PFOA, acutely and reversibly inhibited iodide accumulation by FRTL-5 thyrocytes, as well as by HEK-293 cells transiently expressing the Sodium Iodide Symporter (NIS). PFOS prevented NIS-mediated iodide uptake and reduced intracellular iodide concentration in iodide-containing cells, mimicking the effect of the NIS inhibitor perchlorate. PFOS did not affect iodide efflux from thyroid cells. The results of this study suggest that disruption of iodide homeostasis in thyroid cells may be a potential mechanism for anti-thyroid health effects of PFOS. The study also confirms the utility of the YFP-H148Q/I152 cell-based assay to screen environmental PFAS, and other EDCs, for anti-thyroid activity.

Development and validation of prognostic gene signature for basal-like breast cancer and high-grade serous ovarian cancer

PURPOSE

Molecular similarities have been reported between basal-like breast cancer (BLBC) and high-grade serous ovarian cancer (HGSOC). To date, there have been no prognostic biomarkers that can provide risk stratification and inform treatment decisions for both BLBC and HGSOC. In this study, we developed a molecular signature for risk stratification in BLBC and further validated this signature in HGSOC.

METHODS

RNA-seq data was downloaded from The Cancer Genome Atlas (TCGA) project for 190 BLBC and 314 HGSOC patients. Analyses of differentially expressed genes between recurrent vs. non-recurrent cases were performed using different bioinformatics methods. Gene Signature was established using weighted linear combination of gene expression levels. Their prognostic performance was evaluated using survival analysis based on progression-free interval (PFI) and disease-free interval (DFI).

RESULTS

63 genes were differentially expressed between 18 recurrent and 40 non-recurrent BLBC patients by two different methods. The recurrence index (RI) calculated from this 63-gene signature significantly stratified BLBC patients into two risk groups with 38 and 152 patients in the low-risk (RI-Low) and high-risk (RI-High) groups, respectively (p = 0.0004 and 0.0023 for PFI and DFI, respectively). Similar performance was obtained in the HGSOC cohort (p = 0.0131 and 0.004 for PFI and DFI, respectively). Multivariate Cox regression adjusting for age, grade, and stage showed that the 63-gene signature remained statistically significant in stratifying HGSOC patients (p = 0.0005).

CONCLUSION

A gene signature was identified to predict recurrence in BLBC and HGSOC patients. With further validation, this signature may provide an additional prognostic tool for clinicians to better manage BLBC, many of which are triple-negative and HGSOC patients who are currently difficult to treat.

Iodine status and supplementation before, during, and after pregnancy

Iodine intake is essential for the production of thyroid hormone. Iodine deficiency remains a public health problem in many regions around the world. Iodine deficiency can present as a spectrum of disorders depending on the degree of severity. Pregnant and lactating women are particularly vulnerable to iodine deficiency disorders because of their increased iodine requirements. Severe maternal iodine deficiency has been associated with cretinism or impaired neurodevelopment in children as well as obstetric complications. Universal salt iodization has been shown to prevent these disorders in severely iodine deficient areas. Recently, observational studies have demonstrated an association between mild-to-moderate iodine deficiency and poorer cognitive outcomes in children. In this review, we describe the iodine requirements for pregnant and lactating women, how population iodine status can be assessed, the effects of maternal iodine deficiency and excess, and current data regarding efficacy of iodine supplementation for women who are pregnant or lactating.

Modulation of VEGF Expression and Oxidative Stress Response by Iodine Deficiency in Irradiated Cancerous and Non-Cancerous Breast Cells

Breast cancer remains a major concern and its physiopathology is influenced by iodine deficiency (ID) and radiation exposure. Since radiation and ID can separately induce oxidative stress (OS) and microvascular responses in breast, their combination could additively increase these responses. Therefore, ID was induced in MCF7 and MCF12A breast cell lines by medium change. Cells were then X-irradiated with doses of 0.05, 0.1, or 3 Gy. In MCF12A cells, both ID and radiation (0.1 and 3 Gy) increased OS and vascular endothelial growth factor (VEGF) expression, with an additive effect when the highest dose was combined with ID. However, in MCF7 cells no additive effect was observed. VEGF mRNA up-regulation was reactive oxygen species (ROS)-dependent, involving radiation-induced mitochondrial ROS. Results on total VEGF mRNA hold true for the pro-angiogenic isoform VEGF165 mRNA, but the treatments did not modulate the anti-angiogenic isoform VEGF165b. Radiation-induced antioxidant response was differentially regulated upon ID in both cell lines. Thus, radiation response is modulated according to iodine status and cell type and can lead to additive effects on ROS and VEGF. As these are often involved in cancer initiation and progression, we believe that iodine status should be taken into account in radiation prevention policies.

Possible Effects of Perchlorate Contamination of Drinking Water on Thyroid Health

Background

Perchlorate is an anion that occurs as a contaminant in groundwater. It originates from the improper disposal of ammonium perchlorate, a component of rocket fuel. The objective of this study was to explore whether the exposure to perchlorate in drinking water had an impact on the thyroid function of the population residing near an ammonium perchlorate plant in Kerala. Methodology. Using an ecological study design, we compared the serum levels of thyroid-stimulating hormone, thyroxine, and thyroid peroxidase antibodies among a representative sample of 289 study subjects from the area surrounding the ammonium perchlorate enrichment plant to 281 study subjects in a control area.

Results

The perchlorate concentration in the groundwater varied from 1600 ppb to 57,000 ppb in the 10 samples from the contaminated area and was below 24 ppb in all locations in the control area. No significant differences were found in the mean serum TSH concentration and mean T4 levels between the subjects from the contaminated area and the control area. On regression analysis, perchlorate contamination was not found to be a significant predictor of TSH.

Conclusion

This study did not find any significant association between perchlorate in drinking water and changes in thyroid hormone levels. Our findings indicate the need for further investigation of this hypothesis using urinary perchlorate as a measure of individual exposure.

Allosteric regulation of mammalian Na+/I- symporter activity by perchlorate

The Na⁺/I^- symporter (NIS), the plasma membrane protein that actively transports I^- (stoichiometry 2Na⁺:1I^-) in thyroid physiology and radioiodide-based thyroid cancer treatment, also transports the environmental pollutant perchlorate (stoichiometry 1Na⁺:1ClO₄^-), which competes with I^- for transport. Until now, the mechanism by which NIS transports different anion substrates with different stoichiometries has remained unelucidated. We carried out transport measurements and analyzed these using a statistical thermodynamics-based equation and electrophysiological experiments to show that the different stoichiometry of ClO₄^- transport is due to ClO₄^- binding to a high-affinity non-transport allosteric site that prevents Na⁺ from binding to one of its two sites. Furthermore, low concentrations of ClO₄^- inhibit I^- transport not only by competition but also, critically, by changing the stoichiometry of I^- transport to 1:1, which greatly reduces the driving force. The data reveal that ClO₄^- pollution in drinking water is more dangerous than previously thought.

Genetic and Physiological Factors Affecting Human Milk Production and Composition

Human milk is considered the optimal nutrition for infants as it provides additional attributes other than nutritional support for the infant and contributes to the mother's health as well. Although breastfeeding is the most natural modality to feed infants, nowadays, many mothers complain about breastfeeding difficulties. In addition to environmental factors that may influence lactation outcomes including maternal nutrition status, partner's support, stress, and latching ability of the infant, intrinsic factors such as maternal genetics may also affect the quantitative production and qualitative content of human milk. These genetic factors, which may largely affect the infant's growth and development, as well as the mother's breastfeeding experience, are the subject of the present review. We specifically describe genetic variations that were shown to affect quantitative human milk supply and/or its qualitative content. We further discuss possible implications and methods for diagnosis as well as treatment modalities. Although cases of nutrient-deficient human milk are considered rare, in some ethnic groups, genetic variations that affect human milk content are more abundant, and they should receive greater attention for diagnosis and treatment when necessary. From a future perspective, early genetic diagnosis should be directed to target and treat breastfeeding difficulties in real time.

Iodine Deficiency and Supplementation in Pregnancy

Iodine deficiency during pregnancy is an important global public health issue and the leading preventable cause of neurodevelopmental impairments worldwide. The effects of severe iodine deficiency during pregnancy, including adverse obstetric outcomes and decreased child intelligence quotient, have been clearly established. However, the effects of mild-to-moderate deficiency remain less well understood. Pregnant and lactating women have higher iodine requirements than other adults; intakes of 220 to 250 µg/d in pregnancy and 250 to 290 µg/d in lactation. In this article, we describe iodine metabolism, iodine requirements in pregnancy and lactation, the effects of both iodine deficiency and excessive iodine intakes in pregnancy, and the efficacy of iodine supplementation.

Uptake of [¹⁸F]tetrafluoroborate in MCF-7 Breast Cancer Cells is Induced after Stimulation of the Sodium Iodide Symporter

BACKGROUND

The human sodium iodide symporter (hNIS) has been the most important target in nuclear medicine regarding thyroid-related diseases. Although hNIS-expression can also be determined in extra-thyroidal tumors, imaging hNIS with positron emission tomography has not been exploited clinically.

OBJECTIVE

Here, we evaluated the accumulation of the novel hNIS-substrate [18F]tetrafluoroborate ([18F]TFB) in the endogenously hNIS-expressing breast cancer cell line MCF-7 after an improved radiosynthesis and pharmacological stimulation.

METHODS

[18F]TFB was prepared under mild reaction conditions (40°C, 25 min) and its uptake properties were investigated in MCF-7 cells pretreated with a combination of all-trans retinoic acid plus methasone-derivatives and compared to the clinically established tracers [131I]iodide and [99mTc]pertechnetate. Specificity of the tracer accumulation was assessed by inhibition experiments using NaBF4, KSO3F, KI and KIO3.

RESULTS

[18F]TFB was obtained with a radiochemical yield of 24.0 ± 6.6 % (n = 17) within 40 min after high pressure liquid chromatography-separation and with 26.8 ± 6.2 % (n = 13) within 45 min after adapting the procedure on a synthesis module using higher starting activities (> 10 GBq). After pharmacological treatment, a 4-fold increase in hNIS-expression on the MCF-7 cell surface was achieved, resulting in a significantly higher [18F]TFB uptake into the cells (up to 58-fold) as compared to control experiments. Inhibition studies using various NIS-substrates confirmed the specificity of [18F]TFB for hNIS.

CONCLUSION

[18F]TFB was shown to be a promising hNIS-substrate in our model using the human MCF-7 breast cancer cell line mandating in vivo evaluations in xenografted studies and in patients.

1,25-hydroxyvitamin D3 decreases endoplasmic reticulum stress-induced inflammatory response in mammary epithelial cells

Recent studies indicated that intramammary administration of active vitamin D₃ hormone (1,25D₃) inhibits the inflammatory process associated with mastitis. We hypothesized that attenuation of endoplasmic reticulum (ER) stress by 1,25D₃ in mammary epithelial cells (MECs) is an important cellular mechanism contributing to this beneficial effect of intramammary treatment with 1,25D₃. To test this hypothesis, the effect of 1,25D₃ was studied on induction of ER stress in a transformed human MEC line, MCF-7 cells. Treatment with two different ER stress inducers, thapsigargin (TG) and tunicamycin (TM), caused a dose-dependent induction of ER stress as evident from up-regulation of protein kinase RNA-like ER kinase (PERK), heat shock protein family A (Hsp70) member 5 (HSPA5), activating transcription factor (ATF4), ATF6, DNA damage inducible transcript 3 (DDIT3) and spliced X-box binding protein 1 (sXBP1) and impaired cell viability and decreased expression of vitamin D receptor (VDR) in MCF-7 cells (P < 0.05). Treatment with 1,25D₃ (100 nM) inhibited TG (10 nM)- and TM (1 μg/mL)-induced mRNA and/or protein levels of ATF4, ATF6, DDIT3 and HSPA5 in MCF-7 cells (P < 0.05). In addition, 1,25D₃ (100 nM) antagonized the effect of TG (10 nM) and TM (1 μg/mL) on mRNA and protein levels of VDR and mRNA levels of genes involved in production and degradation of 1,25D₃ in MCF-7 cells (P < 0.05). Moreover, 1,25D₃ (100 nM) inhibited nuclear factor-κB (NF-κB) activation in response to TM (10 nM) and TG (1 μg/mL) in MCF-7 cells. In conclusion, the present findings show that 1,25D₃ is effective in attenuating ER stress and the NF-κB-driven inflammatory response in MCF-7 cells. This indicates that attenuation of ER stress by 1,25D₃ in MECs may contribute to the recently observed inhibitory effect of intramammary treatment of dairy cows with 1,25D₃ on the inflammatory process associated with mastitis.

Breast Milk Iodine Concentration Is Associated with Infant Growth, Independent of Maternal Weight

In breastfed infants, human milk provides the primary source of iodine to meet demands during this vulnerable period of growth and development. Iodine is a key micronutrient that plays an essential role in hormone synthesis. Despite the importance of iodine, there is limited understanding of the maternal factors that influence milk iodine content and how milk iodine intake during infancy is related to postnatal growth. We examined breast milk samples from near 2 weeks and 2 months post-partum in a mother-infant dyad cohort of mothers with pre-pregnancy weight status defined by body mass index (BMI). Normal (NW, BMI < 25.0 kg/m2) is compared to overweight/obesity (OW/OB, BMI ≥ 25.0 kg/m2). The milk iodine concentration was determined by inductively coupled plasma mass spectrometry. We evaluated the associations between iodine content at 2 weeks and infant anthropometrics over the first year of life using multivariable linear mixed modeling. Iodine concentrations generally decreased from 2 weeks to 2 months. We observed no significant difference in iodine based on maternal weight. A higher iodine concentration at 2 weeks was associated with a larger increase in infant weight-for-age and weight-for-length Z-score change per month from 2 weeks to 1 year. This pilot study shows that early iodine intake may influence infant growth trajectory independent of maternal pre-pregnancy weight status.

Analysis Natrium Iodide Symporter Expression in Breast Cancer Subtypes for Radioiodine Therapy Response

Purpose

This study investigates natrium iodide symporter (NIS) expression in three breast cancer subtypes to predict radioiodine response.

Materials and Methods

Frozen breast tissues from triple negative (TN), human epidermal receptor 2 (HER2+), and luminal A cancers were used in this research. NIS protein expression in each subtype was analyzed using immunohistochemistry (IHC) and western blot (WB). Secondary data such as age, subtypes, and Ki 67 index were drawn from the surgical oncologist database. Breast cancer cell lines were used to investigate the effect of radioiodine by measuring cell proliferation.

Results

The forty-one breast cancer samples were analyzed consisted of the following subtypes: TN, HER2+, and luminal A were 58%, 22%, and 20% respectively. The stages of disease were 2A to 4A. Most of samples were at 3B. Ki 67 index of TN, HER2+, and luminal A were 21 ± 12, 19 ± 5, and 7 ± 3 respectively. The NIS expression was detected in 95% of samples in cytoplasm and/or cell membrane; 93% of samples were invasive breast carcinomas. Only 20% of the samples showed NIS expression at cell membrane; four samples were HER2+, and other four were TN subtypes. NIS membrane score was significantly positively correlated with Ki67 index, p = 0.04. NIS protein expression was detected at sizes 88 kDa, 50 kDa, and 27 kDa. Cell proliferation rate means of MDA-MB 231, SKBR3, and MCF7 cells were 81.6 ± 4, 10.6 ± 5, and 15.4 ± 13 respectively (p = 0.009).

Conclusion

NIS protein expression is detectable in breast cancer cells to varying degrees. HER2+ is the most likely to express NIS in the cell membrane followed by TN subtypes. This indicates that radioiodine could be used as a novel adjuvant treatment in breast cancer.

Targeting uptake transporters for cancer imaging and treatment

Cancer cells reprogram their gene expression to promote growth, survival, proliferation, and invasiveness. The unique expression of certain uptake transporters in cancers and their innate function to concentrate small molecular substrates in cells make them ideal targets for selective delivering imaging and therapeutic agents into cancer cells. In this review, we focus on several solute carrier (SLC) transporters known to be involved in transporting clinically used radiopharmaceutical agents into cancer cells, including the sodium/iodine symporter (NIS), norepinephrine transporter (NET), glucose transporter 1 (GLUT1), and monocarboxylate transporters (MCTs). The molecular and functional characteristics of these transporters are reviewed with special emphasis on their specific expressions in cancers and interaction with imaging or theranostic agents [e.g., I-123, I-131, ¹²³I-iobenguane (mIBG), ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and ¹³C pyruvate]. Current clinical applications and research areas of these transporters in cancer diagnosis and treatment are discussed. Finally, we offer our views on emerging opportunities and challenges in targeting transporters for cancer imaging and treatment. By analyzing the few clinically successful examples, we hope much interest can be garnered in cancer research towards uptake transporters and their potential applications in cancer diagnosis and treatment.

Targeting Novel Sodium Iodide Symporter Interactors ADP-Ribosylation Factor 4 and Valosin-Containing Protein Enhances Radioiodine Uptake

The sodium iodide symporter (NIS) is required for iodide uptake, which facilitates thyroid hormone biosynthesis. NIS has been exploited for over 75 years in ablative radioiodine (RAI) treatment of thyroid cancer, where its ability to transport radioisotopes depends on its localization to the plasma membrane. The advent of NIS-based in vivo imaging and theranostic strategies in other malignancies and disease modalities has recently increased the clinical importance of NIS. However, NIS trafficking remains ill-defined. Here, we used tandem mass spectrometry followed by coimmunoprecipitation and proximity ligation assays to identify and validate two key nodes-ADP-ribosylation factor 4 (ARF4) and valosin-containing protein (VCP)-controlling NIS trafficking. Using cell-surface biotinylation assays and highly inclined and laminated optical sheet microscopy, we demonstrated that ARF4 enhanced NIS vesicular trafficking from the Golgi to the plasma membrane, whereas VCP-a principal component of endoplasmic reticulum (ER)-associated degradation-governed NIS proteolysis. Gene expression analysis indicated VCP expression was particularly induced in aggressive thyroid cancers and in patients who had poorer outcomes following RAI treatment. Two repurposed FDA-approved VCP inhibitors abrogated VCP-mediated repression of NIS function, resulting in significantly increased NIS at the cell-surface and markedly increased RAI uptake in mouse and human thyroid models. Collectively, these discoveries delineate NIS trafficking and highlight the new possibility of systemically enhancing RAI therapy in patients using FDA-approved drugs. SIGNIFICANCE: These findings show that ARF4 and VCP are involved in NIS trafficking to the plasma membrane and highlight the possible therapeutic role of VCP inhibitors in enhancing radioiodine effectiveness in radioiodine-refractory thyroid cancer.

Mannose glycosylation is an integral step for NIS localization and function in human breast cancer cells

Chasing an intriguing biological question on the disparity of sodium iodide symporter (NIS, officially known as SLC5A5) expression and function in the clinical scenario of breast cancer, this study addresses key molecular defects involved. NIS in cancer patients has primarily been recorded to be a cytoplasmic protein, thus limiting the scope for targeted radio-iodine therapy. We developed NIS transgene-overexpressing MCF-7 breast cancer cells, and found a few clonal derivatives that show predominant expression of NIS in the plasma membrane. The majority of clones, however, showed cytosolic NIS expression over long passages. Cells expressing membranous NIS show unperturbed dynamic trafficking of NIS through secretory pathway organelles when compared to cells expressing cytoplasmic NIS or to parental cells. Further, treatment of cells expressing membranous NIS with specific glycosylation inhibitors highlighted the importance of inherent glycosylation processing and an 84 gene signature glycosylation RT-Profiler array revealed that clones expressing NIS in their membrane cluster separately compared to the other cells. We further confirm a role of three differentially expressed genes, i.e. MAN1B1, MAN1A1 and MAN2A1, in regulating NIS localization by RNA interference. Thus, this study shows the important role of mannosidase in N-glycosylation processing in order to correctly traffic NIS to the plasma membrane in breast cancer cells.This article has an associated First Person interview with the first author of the paper.

Association between benign thyroid disease and breast cancer: a single center experience

BACKGROUND

The relationship between breast cancer (BC) and thyroid disease (TD) is still controversial. The aim of the study was to investigate the possible coexistence of TD in patients with newly diagnosed BC and its correlation with BC clinical presentation with regard to menopausal status and stage of disease.

METHODS

This is a retrospective cohort study of all patients treated for primary BC between 2014 and 2016 at the Breast Unit of Trieste University Hospital. Clinical charts and reports were reviewed for coexisting thyroid disorders (i.e. hyperthyroidism, hypothyroidism, benign TD, thyroid cancer, thyroid autoimmunity) and menopausal status at the time of BC diagnosis. Biomolecular profile, stage, and grading of BC were also evaluated.

RESULTS

A total of 786 women and 7 men were included in the study. Co-presence of TD was found in 161(20.3%) cases: of these, 151(19.4%) patients presented benign TD and 10(1.3%) patients presented thyroid carcinoma. Thyroid autoimmunity was found in 51(32%) patients. Regarding thyroid function, 88(55%) patients had hypothyroidism, 19(12%) hyperthyroidism, and 54(33%) normal thyroid function. No statistically significant correlation was found between age and TD (p = 0.16), although TD was more common in women aged ≥60 years. Women with BC diagnosed at pre-menopausal age were more likely to have thyroid autoimmune diseases (45% vs. 29%, p = 0.05). No association was detected among BC molecular profiles with either thyroid autoimmunity (p = 0.26) or altered thyroid function (p = 0.63). High-grade BC was more frequent in women with hyperthyroidism (52.9%, p = 0.04), but the grading was independent from the presence of thyroid autoimmune disease (p = 0.87). BC stage was related to both thyroid autoimmunity (p = 0.04) and thyroid function (p < 0.001), with 55.2% of women affected by benign TD presenting with stage I BC and more aggressive BCs found in hypothyroid patients.

CONCLUSIONS

According our study results, patients with primary BC present a greater incidence of autoimmunity disorders, especially when diagnosed in the pre-menopausal setting. However, further prospective studies are required to definitively prove causality.

Variation of iodine concentration in breast milk and urine in exclusively breastfeeding women and their infants during the first 24 wk after childbirth

OBJECTIVE

The aim of this study was to observe the variation of iodine concentration in breast milk and urine in exclusively breastfeeding women and their infants during the first 24 wk after childbirth.

METHODS

In all, 634 exclusively breastfeeding mother-infant pairs were enrolled at hospital and followed at the 1, 4, 8, 12, 16, and 24 wk postpartum. Spot infant urinary iodine concentration (I-UIC), maternal urinary iodine concentration UIC (M-UIC), and breast milk iodine concentration (BMIC) in bilateral breasts were measured.

RESULTS

During the first 24 wk, the median I-UIC was 216 (139-362) and 122 (68-217) μg/L in lactating mothers, both indicating iodine sufficiency. A strong correlation and no difference were found between BMIC in bilateral breasts. The mean BMIC (M-BMIC) of the two breasts was 165 (112-257) μg/L with a Bland-Altman index of 2.1%. Positive correlations were found between M-BMIC and I-UIC (r = 0.353, P < 0.001), between M-BMIC and M-UIC (r = 0.339, P < 0.001), and between I-UIC and M-UIC (r = 0.222, P < 0.001). M-BMIC was significantly higher than M-UIC (P < 0.001) and lower than I-UIC (P < 0.001). M-BMIC declined from week 1 to week 8 postpartum, both I-UIC and M-UIC dropped from week 1 to week 4 postpartum and stabilized thereafter.

CONCLUSION

The iodine nutrition in lactating women and infants were adequate during the first 24 wk after childbirth. M-BMIC declined from week 1 to week 8 postpartum. Both I-UIC and M-UIC dropped from week 1 to week 4 postpartum. Further studies are needed to explore a more definitive BMIC and UIC range for an optimal iodine status in lactating women and breastfed infants.