NIS Expression Research Articles

Effects of bamboo shoots (Bambusa balcooa) on thyroid hormone synthesizing regulatory elements at cellular and molecular levels in thyrocytes.

Bamboo shoots (BS) are consumed in various forms and used largely in naturopathy for curing ailments since ancient times to present days. It is eaten in South East Asian countries in several indigenous preparations. In north east India, it is consumed predominantly and used as natural cure to treat various diseases. Although known for its beneficial effects, adverse effects including goitrogenic/antithyroidal potential are emerging. Endemic goiter exists in Manipur, India even after adequate iodine intake for consumption of BS. It is thus important to study the impact of this goitrogenic food on certain thyroid hormone synthesizing regulatory factors at cellular and molecular level in thyrocytes. Phytochemical analysis of BS - Bambusa balcooa Roxb (BSBR) extract conducted. IC50 of the extract on thyrocytes in culture was determined. To study the antithyroid effects of this goitrogenic food, activity status of Na+-K+-ATPase, TPO and Deiodinase, mRNA and protein expressions of NIS, TPO and PAX8 were investigated with and without extra iodine in culture media. Simultaneously ROS generation in terms of H2O2 and antioxidant status, NO, LPO were assayed. Activities of the studied enzymes decreased depending on dose and time with increased H2O2, decreased antioxidants followed by increased NO with LPO. DNA damage and LDH also increased while mRNA and protein expression of NIS, TPO and PAX8 were downregulated. Extra iodine ameliorated all such effects partially. Bioactive constituents of the extract imbalances oxidative status of thyrocytes impairing action of hormone synthesizing elements at cellular and molecular level.

Integrin αvβ3-Mediated Effects of Thyroid Hormones on Mesenchymal Stem Cells in Tumor Angiogenesis.

Background: Several clinical and experimental studies have implicated thyroid hormones in cancer progression. Cancer-relevant effects, including stimulation of tumor growth and new blood vessel formation by angiogenesis, are thought to be mediated by a nonclassical signaling pathway initiated through integrin αvβ3 expressed on cancer cells and proliferating endothelium. In an earlier study, we established mesenchymal stem cells (MSCs), important contributors to the fibrovascular network of tumors, as new thyroid hormone-dependent targets. Here, we evaluated the effects of the thyroid hormones triiodothyronine (T3) and thyroxine (T4) versus Tetrac, an integrin-specific inhibitor of thyroid hormone action, on MSCs in tumor angiogenesis. Methods: Modulation of the expression and secretion of angiogenesis-relevant factors by thyroid hormones in primary human MSCs and their effect on endothelial cell tube formation were tested in vitro. We further engineered MSCs to express the sodium iodide symporter (NIS) reporter gene under control of a hypoxia-responsive promoter and the vascular endothelial growth factor (VEGF) promoter to test effects on these pathways in vitro and, for VEGF, in vivo in an orthotopic hepatocellular carcinoma (HCC) xenograft mouse model by positron emission tomography imaging. Results: T3 and T4 increased the expression of pro-angiogenic genes in MSCs and NIS-mediated radioiodide uptake in both NIS reporter MSC lines in the presence of HCC cell-conditioned medium. Supernatant from thyroid hormone-treated MSCs significantly enhanced endothelial cell tube formation. Tetrac and/or inhibitors of signaling pathways downstream of the integrin reversed all these effects. Tumoral radioiodide uptake in vivo demonstrated successful recruitment of MSCs to tumors and VEGF promoter-driven NIS expression. Hyperthyroid mice showed an increased radioiodide uptake compared with euthyroid mice, while tracer uptake was markedly reduced in hypothyroid and Tetrac-treated mice. Conclusions: Our data suggest that thyroid hormones influence angiogenic signaling in MSCs via integrin αvβ3 and further substantiate the anti-angiogenic activity of Tetrac in the tumor microenvironment.

Expression of pendrin and NIS iodide transporters in human breast tumor and peri-tumoral tissue.

IntroductionThyroid iodide transporters, Na+/I– symporter (NIS) and pendrin (PDS), are responsible for supplying this vital micronutrient for thyroid hormone synthesis by thyroid peroxidase (TPO). Both proteins were shown to be expressed, apart from the thyroid, also in other human tissues, including lactating mammary gland. NIS expression in human breast cancers has been widely studied. On the other hand, until now PDS mRNA levels in breast tumor tissue have been estimated only in high throughput analyses. Previously, we have observed that TPO is expressed in normal and cancerous human breast tissues and shows enzymatic activity. However, biochemical activity of TPO in human breast cancer cells requires iodide transport by NIS and PDS. Therefore, to extend our previous study on TPO expression and function in human breast tumors we performed analysis of NIS and PDS levels in the same group of patients.Material and methodsThe study involved detection of NIS and PDS protein levels by immunohistochemistry and Western blotting, as well as mRNA levels by real-time quantitative polymerase chain reaction.ResultsHere we provide direct evidence that NIS and PDS are expressed in human breast cancer tissue, with NIS levels being increased and PDS levels decreased in tumor tissue. Interestingly, PDS mRNA levels in breast cancer tissue seem to be influenced by the estrogen receptor status and age of the patients, while NIS mRNA levels were dependent on histological type of the tumor.ConclusionsThis study provides valuable information important for consideration in diagnostic or therapeutic application of radioiodine in breast cancer management.

Antagonistic effects of RAC1 and tumor-related RAC1b on NIS expression in thyroid.

Thyroid cancer (TC) is the most common endocrine malignancy. The sodium-iodide symporter (NIS), responsible for active transport of iodide into thyroid cells, allows the use of radioactive iodine (RAI) as the systemic treatment of choice for TC metastatic disease. Still, patients with advanced forms of TC often lose the ability to respond to RAI therapy, which results in worse survival rates. We have shown that the overexpression of RAC1b, a tumor-related RAC1 splice variant, is associated with less favorable clinical outcomes in differentiated TCs derived from the follicular epithelial (DTCs). RAC1b overexpression is also significantly associated with the presence of MAPK-activating BRAFV600E mutation, which has been previously implicated in the loss of NIS expression. Here, we show that increased RAC1b levels are associated with NIS downregulation in DTCs and demonstrate that ectopic overexpression of RAC1b in non-transformed thyroid cells is sufficient to decrease TSH-induced NIS expression, antagonizing the positive effect of the canonically spliced RAC1 GTPase. Moreover, we clearly document for the first time in thyroid cells that both NIS expression and iodide uptake are hampered by RAC1 inhibition, highlighting the role of RAC1 in promoting TSH-induced NIS expression. Our findings support a role for RAC1 and RAC1b signaling in the regulation of NIS expression in thyroid cells and suggest that RAC1b in cooperation with other cancer-associated signaling cues may be implicated in the response of DTCs to RAI therapy.

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.

Inhibition of microRNA-875-5p promotes radioiodine uptake in poorly differentiated thyroid carcinoma cells by upregulating sodium-iodide symporter.

Poorly differentiated thyroid carcinoma (PDTC) is an endocrine malignancy that is challenging to treat due to its limited radioiodine uptake. microRNAs (miRNAs or miRs) have been shown to be useful in treating many types of tumors, including PDTC. This study aims to evaluate the potential effect of miR-875-5p on the radioiodine uptake of PDTC and to clarify the underlying mechanisms. Expression of miR-875-5p and sodium-iodide symporter (NIS) in tissues and cell lines was determined using RT-qPCR. The binding relationship between miR-875-5p and NIS was predicted through in silico analysis and verified by dual-luciferase reporter gene assay. A series of miR-875-5p mimic, miR-875-5p inhibitor, shRNA against NIS, and overexpressed NIS plasmids were introduced into PDTC cells. We then evaluated the cell viability, colony formation, apoptosis, and radioiodine uptake of each PDTC sample via CCK-8 assay, clonogenic assay, flow cytometry, and γ counter, respectively. miR-875-5p was found to be highly expressed, but NIS was poorly expressed in DTC tissues and PDTC cell lines. NIS was verified to be a target gene of miR-875-5p. Upregulation of miR-875-5p was found to induce PDTC cell proliferation, and reduce apoptosis and radioiodine uptake in vitro through down-regulation of NIS. In an in vivo orthotopic model, the enhancement of miR-875-5p led to the reduction of NIS expression and radioiodine uptake in the thyroid tumors. Altogether, the findings of the current study suggest that down-regulated miR-875-5p expression could promote its target gene NIS to increase radioiodine uptake in PDTC, constituting a preventive strategy against PDTC.

Dual inhibition of BRAF and MEK increases expression of sodium iodide symporter in patient-derived papillary thyroid cancer cells in vitro

BackgroundThe majority of papillary thyroid cancers are driven by acquired mutations typically in the BRAF or RAS genes that aberrantly activate the mitogen-activated protein kinase pathway. This process leads to malignant transformation, dedifferentiation, and a decrease in the expression of the sodium-iodide symporter (NIS; SLC5A5), which results in resistance to radioactive iodine therapy. We sought to determine whether inhibition of aberrant mitogen-activated protein kinase-signaling can restore NIS expression. MethodsWe prospectively developed cultures of papillary thyroid cancers derived from operative specimens and applied drug treatments for 24 hours. Samples were genotyped to identify BRAF and RAS mutations. We performed quantitative PCR to measure NIS expression after treatment. ResultsWe evaluated 24 patient papillary thyroid cancer specimens; BRAFV600E mutations were identified in 18 out of 24 (75.0%); 1 patient tumor had an HRAS mutation, and the remaining 5 were BRAF and RAS wildtype. Dual treatment with dabrafenib and trametinib increased NIS expression (mean fold change 4.01 ± 2.04, P < .001), and single treatment with dabrafenib had no effect (mean fold change 0.98 ± 0.42, P = .84). Tumor samples that had above-median NIS expression increases came from younger patients (39 vs 63 years, P < .05). ConclusionDual treatment with BRAF and MEK inhibitors upregulated NIS expression, suggesting that this treatment regimen may increase tumor iodine uptake. The effect was greatest in tumor cells from younger patients.

Radiation-Induced Amplification of TGFB1-Induced Mesenchymal Stem Cell-Mediated Sodium Iodide Symporter (NIS) Gene 131I Therapy.

The innate tumor homing potential of mesenchymal stem cells (MSCs) has been used for a targeted delivery of the theranostic sodium iodide symporter (NIS) transgene into solid tumors. We have previously shown that external beam radiotherapy (EBRT) results in the enhanced recruitment of NIS-expressing MSCs into human hepatocellular carcinoma (HuH7). In parallel, the tumor-associated cytokine TGFB1 becomes strongly upregulated in HuH7 tumors in response to EBRT. We therefore evaluated the effects of combining focused EBRT (5 Gy) with MSC-mediated systemic delivery of the theranostic NIS transgene under control of a synthetic TGFB1-inducible SMAD-responsive promoter (SMAD-NIS-MSCs) using 123I-scintigraphy followed by 131I therapy in CD1 nu/nu mice harboring subcutaneous human hepatocellular carcinoma (HuH7). Following tumor irradiation and SMAD-NIS-MSC application, tumoral iodide uptake monitored in vivo by 123I-scintigraphy was enhanced as compared with nonirradiated tumors. Combination of EBRT and SMAD-NIS-MSC-mediated 131I therapy resulted in a significantly improved delay in tumor growth and prolonged survival in therapy mice as compared with the combined therapy using CMV-NIS-MSCs or to control groups receiving EBRT or saline only, or EBRT together with SMAD-NIS-MSCs and saline applications. MSC-based NIS-mediated 131I therapy after EBRT treatment dramatically enhanced therapeutic efficacy when a TGFB1-inducible SMAD-responsive promoter was used to drive NIS expression in adoptively applied MSCs. The remarkable therapeutic effect seen is thought to be linked in large part to the enhanced TGFB1 produced in this context, which leads to a highly selective and focused amplification of MSC-based NIS expression within the tumor milieu.

Divergence of Iodine and Thyroid Hormones in the Fetal and Maternal Parts of Human-Term Placenta.

The human placenta is an important organ that forms a barrier where maternal and fetal exchange takes place. The placenta transport iodine to the fetal circulation by transfer of maternal iodine and deiodination of thyroid hormones (THs). The aim of the study was to examine the distribution of iodine and thyroid hormone transporters in the maternal and fetal sides of human-term placenta. A cross-sectional study was performed at the First Affiliated Hospital of China Medical University. Placental samples (maternal and fetal surfaces) were collected from 113 healthy-term pregnant women. The iodine content; the concentration of thyroxine (T4), triiodothyronine (T3), and reverse T3 (rT3); and the enzyme activity of placental type 2 iodothyronine deiodinase (D2) and D3 were examined. The mRNA and protein localization/expression of iodine and thyroid hormone transporters in the placenta were also studied. We also analyzed the association between expression level of Na+/I- symporter (NIS), thyroid hormone transporter protein, D3 activity in maternal and fetal surfaces of placenta with iodine content, and thyroid hormone levels. Iodine levels in placental samples from the maternal side were significantly higher than those in samples from the fetal side. T3 and T4 expression in fetal placenta was significantly lower than in maternal placenta. D3 activity in the fetal side of the placentas was significantly higher than that in the maternal side. The mRNA and protein expression of monocarboxylate transporters 8 (MCT8), L-amino acid transporters 1 (LAT1), organic anion transporting polypeptides 4A1 (OATP4A1), and TH binding protein transthyretin (TTR) were significantly increased in maternal side, while the NIS expression was higher in fetal side of human-term placenta. In conclusion, the enzymatic deiodination of thyroid hormones forms a barrier which reduces transplacental passage of the hormones and that the maternal part of the placenta is the primary factor in the mechanism regulating the hormonal transfer.

Expression of NIS, VEGF-A and Thyroid Autoantibody in Papillary Thyroid Carcinoma with or without Hashimoto’s Disease

Background: Since the incidence of papillary thyroid carcinoma (PTC) combined with Hashimoto’s thyroiditis (HT) has increased year by year, but the mechanism is still unknown, the goal of this study was to investigate the expression of Na⁺/I^– symporter (NIS), vascular endothelial growth factor (VEGF)-A and thyroid autoantibodies in HT combined with PTC, and to explore the relationship between HT and PTC. Methods: Real-time fluorescence quantitative polymerase chain reaction was used to detect the expression of VEGF-A and NIS in 38 cases of PTC and HT combined with PTC and in 20 cases of normal tissues; preoperative serum TPOAb and TgAb levels in each group were detected by ELISA. Results: The expression of VEGF-A in PTC and HT combined with PTC was significantly higher than that in normal tissues (p < 0.05), and the expression of VEGF-A in HT combined with PTC was higher than that in PTC (p < 0.05). The expression of NIS mRNA in PTC and HT combined with PTC was significantly decreased compared to that in normal tissues (p < 0.05), and NIS mRNA in HT combined with PTC tissue was lower than that in PTC tissue (p < 0.05). The preoperative levels of TPOAb and TgAb in the HT combined with PTC group were higher than those in the normal group and the PTC group (p < 0.05). Conclusion: The presence of HT may inhibit iodine uptake and cause a decrease in NIS. Increased levels of TPOAb and TgAb in HT patients lead to a high expression of TSH and stimulate VEGF secretion. This may explain why HT could accelerate the occurrence and development of PTC.

HMGB1-mediated autophagy regulates sodium/iodide symporter protein degradation in thyroid cancer cells

BackgroundSodium/iodide symporter (NIS)-mediated iodide uptake plays an important physiological role in regulating thyroid gland function, as well as in diagnosing and treating Graves’ disease and thyroid cancer. High-mobility group box 1 (HMGB1), a highly conserved nuclear protein, is a positive regulator of autophagy conferring resistance to chemotherapy, radiotherapy and immunotherapy in cancer cells. Here the authors intended to identify the role of HMGB1 in Hank’s balanced salt solution (HBSS)-induced autophagy, explore NIS protein degradation through a autophagy-lysosome pathway in thyroid cancer cells and elucidate the possible molecular mechanisms.MethodsImmunohistochemical staining and reverse transcription-polymerase chain reaction (RT-PCR) were performed for detecting the expression of HMGB1 in different tissues. HMGB1 was knocked down by lentiviral transfection in FTC-133/TPC-1 cells. Autophagic markers LC3-II, p62, Beclin1 and autophagosomal formation were employed for evaluating HMGB1-mediated autophagy in HBSS-treated cells by Western blot, immunofluorescence and electron microscopy. Western blot, quantitative RT-PCR and gamma counter analysis were performed for detecting NIS expression and iodide uptake in HMGB1-knockdown cells after different treatments. The reactive oxygen species (ROS) level, ROS-mediated LC3-II expression and HMGB1 cytosolic translocation were detected by fluorospectrophotometer, flow cytometry, Western blot and immunofluorescence. HMGB1-mediated AMPK, mTOR and p70S6K phosphorylation (p-AMPK, p-mTOR & p-p70S6K) were detected by Western blot. Furthermore, a nude murine model with transplanted tumor was employed for examining the effect of HMGB1-mediated autophagy on imaging and biodistribution of 99mTcO4−. NIS, Beclin1, p-AMPK and p-mTOR were detected by immunohistochemical staining and Western blot in transplanted tumor samples.ResultsHMGB1 was a critical regulator of autophagy-mediated NIS degradation in HBSS-treated FTC-133/TPC-1 cells. And HMGB1 up-regulation was rather prevalent in thyroid cancer tissues and closely correlated with worse overall lymph node metastasis and clinical stage. HMGB1-knockdown dramatically suppressed autophagy, NIS degradation and boosted iodide uptake in HBSS-treated cells. Moreover, HBSS enhanced ROS-sustained autophagy and promoted the cytosolic translocation of HMGB1. A knockdown of HMGB1 suppressed LC3-II conversion and NIS degradation via an AMPK/mTOR-dependent signal pathway through a regulation of ROS generation, rather than ATP. Furthermore, these data were further supported by our in vivo experiment of xenografts formed by HMGB1 knockdown cells reverting the uptake of 99mTcO4− as compared with control shRNA-transfected cells in hunger group.ConclusionsActing as a critical regulator of autophagy-mediated NIS degradation via ROS/AMPK/mTOR pathway, HMGB1is a potential intervention target of radioiodine therapy in thyroid cancer.

Abstract 920: p97/VCP: A novel interactor of the sodium iodide symporter, which can be pharmacologically targeted to increase radioiodine uptake in thyroid and breast cancer cells

Abstract By exploiting the canonical function of the sodium iodide symporter (NIS), ablative radioiodine therapy is an effective treatment for papillary thyroid cancer (PTC). Unfortunately, ~25% of PTC patients are unable to accumulate therapeutically sufficient radioiodine due to diminished expression and/or altered plasma membrane localization of NIS. Patients with radioiodine-refractory PTC have reduced mean survival times. Radioiodine therapy has been proposed as a viable treatment for breast cancer but is hampered by low levels of membranous NIS localization. Currently, however, the regulation of NIS membrane localization remains ill-defined. Mass spectrometry identified the protein p97/VCP as a novel NIS interactor, which was validated through co-immunoprecipitation and proximity ligation assays. p97 siRNA depletion increased NIS-mediated radioiodine uptake by 97% and 141% in the lentivirally-expressing NIS MDA-MB-231 breast and TPC1 thyroid cancer cell lines respectively (p&amp;lt;0.05), and significantly boosted endogenous NIS function in human primary thyrocytes (p&amp;lt;0.05). Conversely, p97 overexpression significantly repressed NIS function in all cell systems, accompanied by lowered membranous NIS localization (p&amp;lt;0.05), as quantified via cell surface biotinylation assays. We next identified five different allosteric p97 inhibitors - Eeyarestatin-1, NMS-873, Astemizole, Clotrimazole and Ebastine - which were all able to overcome p97 inhibition of NIS function in TPC1 and MDA-MB-231 cell lines lentivirally-expressing NIS, significantly increasing NIS function by at least 100%. TCGA analyses of matched PTCs revealed p97 mRNA expression is highly upregulated in PTC compared to matched normal thyroid (n=58, p&amp;lt;0.05), providing a putative explanation for repressed NIS function. In a wider cohort of 413 PTC patients, high tumoral p97 expression was associated with a worse disease-free survival when compared to low p97 expression (p&amp;lt;0.01, hazard ratio (HR): 2.924 (95% CI, 1.280-6.683)). Strikingly, in patients that did not receive radioiodine, high tumoral p97 expression had no significant effect on disease-free survival (n=136, p=NS, HR: 0.020 (95% CI, 0.000013-31.192)), whereas in patients who received radioiodine, high tumoral p97 expression resulted in a markedly worse disease-free survival (n=194, p&amp;lt;0.01, HR: 6.043 (95% CI, 1.749-20.879)). This is indicative that high p97 expression correlates with a worse response to radioiodine therapy. Our data therefore highlight a new pathway of NIS regulation. Critically, two of these p97 inhibitors are already FDA-approved, highlighting a novel potential therapeutic strategy for enhancing radioiodine uptake in patients with radioiodine-refractory PTC and increasing the feasibility of radioiodine therapy in breast cancer via the transient inhibition of p97 activity. Citation Format: Alice Fletcher, Martin L. Read, Vikki L. Poole, Vicki E. Smith, Christopher J. McCabe. p97/VCP: A novel interactor of the sodium iodide symporter, which can be pharmacologically targeted to increase radioiodine uptake in thyroid and breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 920.

β-catenin nuclear translocation represses thyroid cancer stem cells differentiating into cells with sodium-iodine symporter functional expression

Objective: To confirm whether β-catenin nuclear translocation in thyroid cancer stem cells can differentiate into thyroid cancer cells without functional membrane expression of sodium-iodine transporter (NIS) and be resistant to iodide 131 treatment. Methods: Thyroid cancer stem cells were firstly isolated as a side population (SP) from human thyroid cancer cell line FTC133. The SP cells from FTC133 were transfected with β-catenin, and then differentiated. The cells were further collected for Western blot, Transwell and MTT assay to investigate the epithelial-mesenchymal transition (EMT) characteristics, tumor growth, invasion, and iodine uptake potency in vitro. Functional NIS expression and iodide uptake in differentiated cells were detected with immunofluorescent staining and iodide uptake assay, respectively. Subcutaneous severe combined immunodeficient (SCID) mice tumor model was induced with differentiated cancer cells to explore the in vivo effect of radioiodine treatment. Further immunohistochemical staining was performed to reveal the changes of functional proteins involved in tumor radioiodine treatment. Results: Side population was isolated from FTC133 accounting for about 0.03%, with high expression of stem cell markers and decreased expression of differentiated cell markers. Western blot showed prominent EMT phenotype in the differentiated cells from β-catenin transfected stem cell model, with absence of epithelial expression of E-cadherin and cytokeratin 18, as well as abnormal expression of vimentin,fibronectin and urokinase-type plasminogen activator. Moreover,compared with cells differentiated from untransfected or empty plasmid transfected stem cells, in vitro proliferation markedly increased 85.4% and 81.0%, respectively (both P<0.01); while in vitro invasion augmented 78.8% and 84.4%, respectively (both P<0.01). Immunofluorescent staining identified that, after transfected with β-catenin, differentiated cells underwent β-catenin nuclear translocation and NIS localization transferred from membrane to plasma, compared with cells from untransfected or empty plasmid transfected stem cells. Cell iodide uptake in vitro decreased about 52.8% and 45.2%, respectively (both P<0.01). Furthermore, in vivo experiment further demonstrated that, cells differentiated from β-catenin transfected stem cells were found with much higher tumor proliferation,tumor growth rate and larger tumor mass after radioiodine 131 treatment (both P<0.05). Conclusion: Induction of β-catenin nuclear translocation in stem cells may generate differentiated thyroid cancer cells that are not sensitive to radioiodine treatment.

The cholesterol-derived metabolite dendrogenin A functionally reprograms breast adenocarcinoma and undifferentiated thyroid cancer cells

Dendrogenin A (DDA) is a tumor suppressor mammalian cholesterol-derived metabolite and a new class of ligand of the Liver X receptor (LXR), which displays tumor cell differentiation. In human MCF7 breast adenocarcinoma cells, DDA-induced cell differentiation was associated with an increased accumulation of neutral lipids and proteins found in milk indicating that DDA re-activates some functions of lactating cells. Active iodide transport occurs in the normal lactating mammary cells through the sodium/iodide symporter (NIS) and iodide (I) is secreted into milk to be used by the nursing newborn for thyroid hormones biosynthesis. In the present study, we assessed whether DDA may induce other characteristic of lactating cells such as NIS expression and iodine uptake in MCF7 breast cancer cells and extended this study to the papillary B-CPAP and undifferentiated anaplastic 8505c thyroid cancer cells. Moreover, we evaluated DDA impact on the expression of thyroid specific proteins involved in thyroid hormone biogenesis. We report here that DDA induces NIS expression in MCF7 cells and significantly increases the uptake of 131-I by acting through the LXR. In addition, DDA induces phenotypic, molecular and functional characteristics of redifferentiation in the two human thyroid carcinoma cell lines and the uptake of 131-I in the undifferentiated 8505c cells was associated with a strong expression of all the specific proteins involved in thyroid hormone biosynthesis, TSH receptor, thyroperoxidase and thyroglobulin. 131-I incorporation in the 8505c cells was stimulated by DDA as well as by the synthetic LXR ligand, GW3965. Together these data show that the re-differentiation of breast and thyroid cancer cells by DDA, is associated with the recovery of functional NIS expression and involves an LXR-dependent mechanism. These results open new avenues of research for the diagnosis of thyroid cancers as well as the development of new therapeutic approaches for radioiodine refractory thyroid cancers.

NIS and epithelial-mesenchymal transition marker expression of circulating tumor cells for predicting and monitoring the radioactive iodine-131 therapy effect in differentiated thyroid cancers.

Current methods, such as serum thyroglobulin measurement and medical imaging, have limitations in the routine monitoring of the disease status and treatment response of patients with differentiated thyroid cancers (DTCs), and additional methods remain to be explored. The aim of this study was to investigate the clinical value of the sodium/iodide symporter (NIS) expression and epithelial-mesenchymal transition (EMT) phenotypes of circulating tumor cells (CTCs) in monitoring the disease status and treatment response of DTC. Blood samples were obtained from DTC patients before (1 to 3months after total thyroidectomy) and 4 to 6months after radioactive iodine-131 (RAI) therapy for the CTC assessments. The number, NIS expression, and EMT phenotypes of CTCs were enumerated and characterized with CanPatrol™ CTC enrichment and mRNA in situ hybridization. Postoperative NIS high expression was independently correlated with a better response to first RAI therapy and good treatment efficacy. Postoperative NIS-/epithelial-/mesenchymal+ CTCs presence was independently correlated with a worse response to first RAI therapy. The numbers of total NIS+ CTCs and NIS+/epithelial+/mesenchymal+ CTCs after first RAI therapy were negatively correlated with a better response to RAI therapy only in univariate analyses. Univariate and multivariate analyses showed that a decreased or unchanged number of total NIS+ CTCs after RAI therapy may denote good efficacy and effective RAI therapy. These preliminary data suggest that assessment of the NIS expression and EMT phenotypes of CTCs may serve as potential adjuncts for predicting and monitoring the curative effect of RAI therapy in DTC patients and avoid ineffective treatment. Further validation is warranted.

Effect of excessive iodine intake on the 99Tcm-pertechnetate uptake function of thyroid and the related mechanism

Objective To study the influence of excessive iodine intake on the 99Tcm-pertechnetate uptake function of thyroid and explore the related mechanism. Methods A total of 150 male Wistar rats were divided into normal iodine group (NI group) and 4 high iodine (HI) groups (10HI, 50HI, 100HI and 500HI group) with completely random method. Each group included 30 rats. Rats in HI groups were intragastrically administrated with different concentrations of KIO3, and rats in NI group were administrated with the same amount of distilled water. After a 7 d HI diet, each group was randomly divided into 3 subgroups: 7 d group (HI diet for 7 d), 10 d group (HI diet for 7 d + limiting iodine for 3 d) and 14 d group (HI diet for 7 d + limiting iodine for 7 d). All rats were given 1.85 MBq 99TcmO4-, then the thyroid glands were isolated and weighed 20 min post-injection. The radioactive counts were measured and the thyroid uptake percentage activity of injected dose per gram of tissue (%ID/g) of 99TcmO4- for each sample was calculated. Sodium-iodide symporter (NIS) expression level was analyzed by Western blot. One-way analysis of variance or Welch test was used to compare the differences among groups, and Spearman rank correlation analysis was also used. Results At the same observation time, the %ID/g of 99TcmO4- and NIS expression among different HI groups were statistically significant (F values: 48.825-119.219, all P 0.05). Significant differences of %ID/g of 99TcmO4- and NIS expression were found among different time subgroups in 50HI, 100HI and 500HI groups (F values: 10.442-90.408, all P<0.01). Spearman correlation analysis showed that the concentration of iodine correlated negatively with %ID/g of 99TcmO4- and NIS expression (rs values: -0.853 and -0.950, both P<0.01), while the %ID/g of 99TcmO4- and NIS expression was positively correlated (rs=0.925, P<0.01). Conclusions Excessive iodine intake can inhibit thyroid uptake of 99TcmO4- in rats, which is associated with the down-regulation of NIS expression. The degree of inhibition correlates positively with iodine concentration, and correlates negatively with NIS expression. The degree of recovery of NIS and %ID/g of 99TcmO4- may relate to the time of limiting the iodine intake. Key words: Thyroid gland; Sodium pertechnetate Tc 99m; Iodine; Rats; Sodium/iodide symporter

SUN-339 External Beam Radiation Therapy Improves TGFB1-Induced Mesenchymal Stem Cell-Mediated NIS Gene 131I Therapy

The sodium iodide symporter (NIS) is the operational molecule that has allowed the efficient treatment of thyroid malignancies by the administration of 131I for over 70 years. Various vector-driven approaches are currently under investigation to introduce the NIS gene into non-thyroidal tumors in order to more broadly apply this effective anticancer therapy. One such system makes use of genetically engineered mesenchymal stem cells (MSC) as therapy vehicles for the delivery of NIS into solid tumors. MSCs show an innate ability to home to and invade tumor environments in response to the danger signals and inflammatory cytokines produced by the tumor milieu. We and others have demonstrated that tissue or signal-specific gene promoters are able to enhance the specificity of MSC-mediated NIS transgene expression in tumors. External beam radiation therapy (EBRT), a standard principal therapeutic modality for the treatment of cancer, results in tissue damage and hence enhanced recruitment of NIS-expressing MSCs into human hepatocellular carcinoma (HuH7). At the same time, the tumor-associated cytokine TGFB1 is strongly upregulated in HuH7 tumors in response to radiation pretreatment. In the current study, we show that combining EBRT with MSC-based NIS-mediated 131I therapy dramatically enhances therapeutic efficacy when a synthetic TGFB1-inducible SMAD-responsive promoter, as opposed to a constitutive CMV-promoter, is used to drive NIS expression in MSCs. It is thought that the remarkable therapeutic effect seen is linked to the enhanced TGFB1 produced in this context, which leads to a highly selective and focused amplification of MSC-based NIS expression within the tumor milieu.

Decreased All- trans Retinoic Acid-Induced Expression of Sodium-Iodide Transporter in Mammary Epithelial Cells Caused by Conjugated Linoleic Acid Isomers.

Expression of sodium-iodide symporter (NIS) is stimulated by sterol-regulatory-element-binding transcription factors (SREBFs) in mammary epithelial MCF-7 cells. Because conjugated linoleic acid (CLA) isomers have been shown to inhibit transcriptional activity of SREBFs in the mammary gland, the hypothesis was tested that CLA isomers inhibit NIS expression induced by all- trans retinoic acid (ATRA) in MCF-7 cells through inhibiting SREBF activity. c9t11-CLA and t10c12-CLA decreased ATRA-induced NIS-mRNA expression from 1.00 (ATRA alone) to 0.80 ± 0.12 (200 μM c9t11-CLA, P < 0.05) and 0.62 ± 0.10 (200 μM t10c12-CLA, P < 0.05), NIS-protein expression from 1.00 (ATRA alone) to 0.77 ± 0.08 (200 μM c9t11-CLA, P < 0.05) and 0.63 ± 0.05 (200 μM t10c12-CLA, P < 0.05), and NIS-promoter activity from 1.00 (ATRA alone) to 0.74 ± 0.13 (200 μM c9t11-CLA, P < 0.05) and 0.76 ± 0.13 (200 μM t10c12-CLA, P < 0.05); however, c9t11-CLA and t10c12-CLA increased the mRNA levels of SREBF isoforms and their target genes. In contrast, the mRNA expression of peroxisome-proliferator-activated receptor γ (PPARG) was strongly induced by ATRA alone but decreased by CLA isomers from 1.00 (ATRA alone) to 0.80 ± 0.06 (200 μM c9t11-CLA, P < 0.05) and 0.86 ± 0.06 (200 μM t10c12-CLA, P < 0.05). Overexpression of PPARγ in MCF-7 cells increased basal NIS-promoter activity, and treatment with the PPARγ ligand troglitazone stimulated ATRA-induced NIS-promoter activity. In conclusion, the results suggest that CLA isomers exert their effect on the expression of NIS by decreasing PPARG expression in MCF-7 cells.

The Influence of Energy Depletion by Metformin or Hypocaloric Diet on Thyroid Iodine Uptake in Healthy Volunteers: a Randomized Trial

Sufficient thyroid iodine uptake is needed to ensure effective radioactive iodine (RAI) treatment, which is mediated by the sodium-iodide symporter (NIS). Activation of AMP-activated-protein-kinase (AMPK), leads to decreased NIS expression and thyroid iodine uptake in in vitro and animal models. Clinically relevant conditions that lead to AMPK activation include metformin use and hypocaloric conditions. Here, we aim to assess the effects of metformin and hypocaloric diet on thyroid iodine uptake in healthy volunteers. Healthy male volunteers were included and randomized. Group 1 (n = 8) received metformin, group 2 (n = 7) followed a hypocaloric diet (1500 kcal/day), superposed on a moderate iodine restriction diet; Baseline measurements included thyroid iodine-123 (I-123) uptake and TSH, fT4, T3 and rT3 levels. After two weeks, thyroid function and I-123 uptake measurements were repeated. Baseline characteristics were similar between groups. Levels of TSH and fT4 were similar after each intervention. T3 decreased after hypocaloric diet and metformin (−0.2 ± 0.19 nmol/L, p = 0.0327; respectively −0.13 ± 0.13 nmol/L, p = 0.0282), resulting in decreased T3/rT3 ratios. There was no significant difference in thyroid I-123 uptake after each intervention. In conclusion, metformin treatment and hypocaloric diet resulted in a significant decrease in T3 levels and T3/rT3 ratios in healthy volunteers, without significant effects on thyroid iodine uptake. We found no indications that metformin or hypocaloric diet will have clinically relevant effects on RAI uptake.

Over-expression of miR-206 decreases the Euthyrox-resistance by targeting MAP4K3 in papillary thyroid carcinoma

PurposemicroRNAs (miRNAs) play a critical role in drug resistance of multiple cancers including papillary thyroid carcinoma (PTC), indicating the potential of miRNAs as chemoresistance regulators in cancer treatment. The aim of this paper is to explore the relationship between miR-206 and chemoresistance of PTC. MethodsqRT-PCR was conducted to examine the expression of miR-206 in PTC tissues, parental and TPC-1/euthyrox. The CCK-8 assay, EdU assay and flow cytometry were performed to test cells viability, proliferation and apoptosis, respectively. Luciferase reporter assay was used to confirm the potential target of miR-206. Western blotting analysis was performed to evaluate the expressions of related-proteins. ResultsmiR-206 was significantly down-regulated in PTC tissues, parental and TPC-1/euthyrox. Moreover, the expression of miR-206 was exceptionally lower in TPC-1/euthyrox cells than that in TPC-1 cells. Furthermore, we found that over-expression of miR-206 could notably decrease the IC50 values both in TPC-1 and TPC-1/euthyrox cells, which indicated that miR-206 played an essential role in the euthyrox resistance in PTC. In addition, up-regulation of miR-206 inhibited the proliferation, induced apoptosis, suppressed the expressions of multidrug resistance-related proteins, including p-gp, MRP, BCRP and LRP, in euthyrox-resistant PTC cells. Besides, over-expression of miR-206 could notably promoted the expression of NIS, an intrinsic membrane protein that mediates the active transport of iodide into the thyroid and other tissues, playing a critical role in the progress. Further, miR-206 was demonstrated to be able to bind to MAP4K3 and negatively regulated the expression of MAP4K3. Besides, MAP4K3 was clearly up-regulated in PTC tissues, parental and TPC-1/euthyrox cells, and down-regulation of miR-206 attenuated the effect of si-MAP4K3 on the euthyrox sensitivity in euthyrox-resistant PTC cells. Moreover, TPC-1/euthyrox cells transfected with miR-206 mimics could significantly inhibit the expressions of p-p38, p-JNK and p-Erk, which indicated that miR-206 might play an essential role in the euthyrox resistance in PTC by negatively regulating the p38 and JNK signaling pathway. ConclusionmiR-206 contributed to euthyrox resistance in PTC cells through blockage p38 and JNK signaling pathway by targeting MAP4K3, providing a potential therapeutic application for the treatment of patients with euthyrox-resistant PTC in the further.