A perspective view of sodium iodide symporter research and its clinical implications

Dual targeting of MAPK and PI3K pathways unlocks redifferentiation of Braf-mutated thyroid cancer organoids

Thyroid cancer is the most common endocrine malignancy and several genetic events have been described to promote the development of thyroid carcinogenesis. Besides the effects of specific mutations on thyroid cancer development, the molecular mechanisms controlling tumorigenesis, tumor behavior, and drug resistance are still largely unknown. Cancer organoids have been proposed as a powerful tool to study aspects related to tumor development and progression and appear promising to test individual responses to therapies. Here, using mESC-derived thyroid organoids, we developed a BrafV637E-inducible model able to recapitulate the features of papillary thyroid cancer in vitro. Overexpression of the murine BrafV637E mutation, equivalent to BrafV600E in humans, rapidly triggers to MAPK activation, cell dedifferentiation, and disruption of follicular organization. BrafV637E-expressing organoids show a transcriptomic signature for p53, focal adhesion, ECM-receptor interactions, EMT, and inflammatory signaling pathways. Finally, PTC-like thyroid organoids were used for drug screening assays. The combination of MAPK and PI3K inhibitors reversed BrafV637E oncogene-promoted cell dedifferentiation while restoring thyroid follicle organization and function in vitro. Our results demonstrate that pluripotent stem cells-derived thyroid cancer organoids can mimic tumor development and features while providing an efficient tool for testing novel targeted therapies.

Bisphenol analogues induce thyroid dysfunction via the disruption of the thyroid hormone synthesis pathway

Bisphenol analogues are widely used in industrial and daily-use consumer products having imperfect thyroid hormones (THs) structures. Widespread exposure interferes with thyroid-related health outcomes in human. The mechanisms of disruption on TH synthesis and subsequent thyroid dysfunction by different bisphenol analogues remain unclear. Here, we evaluated bisphenol-induced thyroid endocrine disruption in C57BL/6 mice at doses of 0.002, 0.02, 2, and 20 mg/kg body weight/day (BW/d) for five consecutive weeks. Administration of 20 mg/kg BW/d bisphenol S (BPS) and 2 mg/kg BW/d tetrabromobisphenol S (TBBPS) significantly increased serum thyrotropin (TSH) levels to 1.21-fold and 1.20-fold of control group, respectively, indicating that bisphenols induced thyroid dysfunction in mice. Height of the thyroid follicle epithelium significantly increased to 1.27-, 1.24-, 1.26-, and 1.36-fold compared to control group with BPA, BPS, TBBPA, and TBBPS at 20 mg/kg BW/d, respectively, indicating impairment of the thyroid gland structure, and TBBPS showed potent effect. Exposure to bisphenol analogues of 0.02 mg/kg BW/d downregulated the protein expression levels of thyrotropin receptor, the sodium/iodide symporter, thyroperoxidase. The TH-dependent effects were further determined using the T-Screen assay at 10-11 M to 10-5 M concentrations. Bisphenol analogues significantly decreased TH-dependent GH3 cell proliferation, indicating the antagonistic activity of bisphenol analogues. The gene responsible for THs synthesis of thyrotropin releasing hormone receptor and TSH were upregulated, but downregulation of thyroid receptor β was observed. Our results suggest that bisphenol analogues distinctly induce thyroid dysfunction via TH synthesis, implying adverse effect of bisphenol analogues on TH homeostasis and subsequent physiological processes.

The role of BRAF V600E mutation in post-surgical 131I therapy in papillary thyroid carcinoma: a study based on SPECT-CT uptake analysis

BACKGROUND

The BRAF V600E mutation (BRAF mut) in papillary thyroid cancer (PTC) has been associated with poor response to therapy with ¹³¹I in patients with metastases but the results in postsurgical treatment are controversial. Our main objective is to investigate the impact of the mutation on the biokinetics of the administered ¹³¹I therapy after surgery.

METHODS

A prospective study was designed, from July 2015 to January 2018 which included patients with PTC receiving ¹³¹I therapy after surgical treatment. To study the biokinetics of the radioiodine in postoperative thyroid remnants, SPECT-CT images were acquired so as to obtain the following variables: percentage of remnant uptake at 2 and 7 days post-administration, effective half-life and time-integrated activity coefficient. All of them were compared depending on the mutational diagnosis and other clinical features and pathological variables.

RESULTS

Sixty-one patients, and in total 103 thyroid remnants, were included. About 59% of patients were BRAF mutated. The mutation was associated with classic variant (88.5% vs. 11.5%; P=0.0001), desmoplastic reaction (85.7% vs. 14.3%; P=0.002), smaller tumor size (1.5 vs. 2.1 cm; P=0.024), nodal disease (3.3 vs. 1; P=0.001) and advanced stages (76.9% vs. 23%; P=0.014). The BRAFmut group had a lower percentage of ¹³¹I uptake at 2 days (0.17% vs. 0.47%; P=0.001) and at 7 days (0.02% vs. 0.1%; P=0.013); and a lower time-integrated activity coefficient (0.05h vs. 0.17 h; P=0.002). In univariate analysis, in addition to the mutation, the histological variant was significant but only for time-integrated activity coefficient (P=0.04). In multivariate analysis, only mutation determined the 2-day uptake (P<0.001) and the time-integrated activity coefficient (P<0.001).

CONCLUSIONS

The BRAF V600E mutation is associated with lower ¹³¹I uptake in thyroid remnants. Furthermore, it is an independent factor that decreases the effect of post-surgical ¹³¹I therapy, and therefore, it could be used as a potential tool to optimize the treatment of PTC.

Overexpression of Both Human Sodium Iodide Symporter (NIS) and BRG1-Bromodomain Synergistically Enhances Radioiodine Sensitivity by Stabilizing p53 through NPM1 Expression

Improved therapeutic strategies are required to minimize side effects associated with radioiodine gene therapy to avoid unnecessary damage to normal cells and radiation-induced secondary malignancies. We previously reported that codon-optimized sodium iodide symporter (oNIS) enhances absorption of I-131 and that the brahma-associated gene 1 bromodomain (BRG1-BRD) causes inefficient DNA damage repair after high-energy X-ray therapy. To increase the therapeutic effect without applying excessive radiation, we considered the combination of oNIS and BRG1-BRD as gene therapy for the most effective radioiodine treatment. The antitumor effect of I-131 with oNIS or oNIS+BRD expression was examined by tumor xenograft models along with functional assays at the cellular level. The synergistic effect of both BRG1-BRD and oNIS gene overexpression resulted in more DNA double-strand breaks and led to reduced cell proliferation/survival rates after I-131 treatment, which was mediated by the p53/p21 pathway. We found increased p53, p21, and nucleophosmin 1 (NPM1) in oNIS- and BRD-expressing cells following I-131 treatment, even though the remaining levels of citrulline and protein arginine deiminase 4 (PAD4) were unchanged at the protein level.

Sinomenine Hydrochloride Promotes TSHR-Dependent Redifferentiation in Papillary Thyroid Cancer

Radioactive iodine (RAI) plays an important role in the diagnosis and treatment of papillary thyroid cancer (PTC). The curative effects of RAI therapy are not only related to radiosensitivity but also closely related to the accumulation of radionuclides in the lesion in PTC. Sinomenine hydrochloride (SH) can suppress tumor growth and increase radiosensitivity in several tumor cells, including PTC. The aim of this research was to investigate the therapeutic potential of SH on PTC cell redifferentiation. In this study, we treated BCPAP and TPC-1 cells with SH and tested the expression of thyroid differentiation-related genes. RAI uptake caused by SH-pretreatment was also evaluated. The results indicate that 4 mM SH significantly inhibited proliferation and increased the expression of the thyroid iodine-handling gene compared with the control group (p < 0.005), including the sodium/iodide symporter (NIS). Furthermore, SH also upregulated the membrane localization of NIS and RAI uptake. We further verified that upregulation of NIS was associated with the activation of the thyroid-stimulating hormone receptor (TSHR)/cyclic adenosine monophosphate (cAMP) signaling pathway. In conclusion, SH can inhibit proliferation, induce apoptosis, promote redifferentiation, and then increase the efficacy of RAI therapy in PTC cells. Thus, our results suggest that SH could be useful as an adjuvant therapy in combination with RAI therapy in PTC.

Redox Homeostasis in Thyroid Cancer: Implications in Na+/I- Symporter (NIS) Regulation

Radioiodine therapy (RAI) is a standard and effective therapeutic approach for differentiated thyroid cancers (DTCs) based on the unique capacity for iodide uptake and accumulation of the thyroid gland through the Na⁺/I⁻ symporter (NIS). However, around 5–15% of DTC patients may become refractory to radioiodine, which is associated with a worse prognosis. The loss of RAI avidity due to thyroid cancers is attributed to cell dedifferentiation, resulting in NIS repression by transcriptional and post-transcriptional mechanisms. Targeting the signaling pathways potentially involved in this process to induce de novo iodide uptake in refractory tumors is the rationale of “redifferentiation strategies”. Oxidative stress (OS) results from the imbalance between ROS production and depuration that favors a pro-oxidative environment, resulting from increased ROS production, decreased antioxidant defenses, or both. NIS expression and function are regulated by the cellular redox state in cancer and non-cancer contexts. In addition, OS has been implicated in thyroid tumorigenesis and thyroid cancer cell dedifferentiation. Here, we review the main aspects of redox homeostasis in thyrocytes and discuss potential ROS-dependent mechanisms involved in NIS repression in thyroid cancer.

The Role of the Kinase Inhibitors in Thyroid Cancers

Thyroid cancer is the most common endocrine malignancy, accounting for about 3% of all cancer cases each year worldwide with increasing incidence, but with the mortality remaining stable at low levels. This contradiction is due to overdiagnosis of indolent neoplasms identified by neck ultrasound screening that would remain otherwise asymptomatic. Differentiated thyroid carcinomas (DTCs) are almost curable for 95% with a good prognosis. However, 5% of these tumours worsened toward aggressive forms: large tumours with extravasal invasion, either with regional lymph node or distant metastasis, that represent a serious clinical challenge. The unveiling of the genomic landscape of these tumours shows that the most frequent mutations occur in tyrosine kinase receptors (RET), in components of the MAPK/PI3K signalling pathway (RAS and BRAF) or chromosomal rearrangements (RET/PTC and NTRK hybrids); thus, tyrosine-kinase inhibitor (TKI) treatments arose in the last decade as the most effective therapeutic option for these aggressive tumours to mitigate the MAPK/PI3K activation. In this review, we summarize the variants of malignant thyroid cancers, the molecular mechanisms and factors known to contribute to thyroid cell plasticity and the approved drugs in the clinical trials and those under investigation, providing an overview of available treatments toward a genome-driven oncology, the only opportunity to beat cancer eventually through tailoring the therapy to individual genetic alterations. However, radiotherapeutic and chemotherapeutic resistances to these anticancer treatments are common and, wherever possible, we discuss these issues.

A Critical Balance Between PAX8 and the Hippo Mediator TAZ Determines Sodium/Iodide Symporter Expression and Function

Background: The Hippo pathway has a fundamental role in tissue homeostasis, but little is known about how this signaling cascade is controlled in the thyroid. PAX8 is an essential driver of thyroid differentiation and is involved in the control of genes crucial for thyroid hormone biosynthesis, including the sodium/iodide symporter (NIS; SLC5A5). A role for the Hippo mediator transcriptional coactivator with PDZ-binding motif (TAZ) as a coactivator of PAX8 to promote thyroglobulin expression has been previously described. Here, we studied the role of TAZ on thyroid differentiation focusing on PAX8-mediated Slc5a5 transcription. Methods: Gene silencing and overexpression assays were performed in rat PCCl3 thyroid follicular cells (TFCs) to determine the role of TAZ in the regulation of Slc5a5. Transcriptional activity of the Hippo mediators was investigated by chromatin immunoprecipitation and promoter-reporter gene activity. Hippo component levels and location were analyzed in PCCl3 cells and in mouse thyroid under different treatment conditions. Results: By suppressing the expression of PAX8 and its binding to the Slc5a5 upstream enhancer, TAZ inhibits Slc5a5 expression, impairing NIS membrane location and activity. Other Hippo effectors such as YAP1 and TEAD1 were not required for the repressor effect of TAZ. We also found an interplay between the Hippo, thyrotropin (TSH), and transforming growth factor β1 (TGFβ) pathways in TFCs. TSH via cyclic adenosine monophosphate activated Hippo signaling pathway and, consequently, TAZ was excluded from the nucleus. We confirmed this in hypothyroid mice, characterized by elevated TSH serum levels, which showed downregulated activation of Hippo signaling in thyroid. Conversely, TAZ nuclear retention was promoted by TGFβ, a potent NIS repressor, and TAZ silencing markedly relieved the TGFβ-induced inhibition of the symporter. Conclusions: We demonstrate that the effects of TAZ are promoter specific, as it functions as a corepressor of PAX8 to modulate Slc5a5 expression in TFCs. Overall, our data place TAZ as an integrator of the different signaling pathways that control NIS expression, pointing to a role for TAZ in thyroid differentiation and identifying the Hippo pathway as a relevant target to recover NIS levels in thyroid cancer cells.

Evaluation of [18F]tetrafluoroborate as a Potential PET Imaging Agent in a Sodium Iodide Symporter-Transfected Cell Line A549 and Endogenous NIS-Expressing Cell Lines MKN45 and K1

[¹⁸F]tetrafluoroborate (TFB) has been introduced as the ¹⁸F-labeled PET imaging probe for the human sodium iodide symporter (NIS). Noninvasive NIS imaging using [¹⁸F]TFB has received much interest in recent years for evaluating various NIS-expressing tumors. Cancers are a global concern with enormous implications; therefore, improving diagnostic methods for accurate detection of cancer is extremely important. Our aim was to investigate the PET imaging capabilities of [¹⁸F]TFB in NIS-transfected lung cell line A549 and endogenous NIS-expressing tumor cells, such as thyroid cancer K1 and gastric cancer MKN45, and broaden its application in the medical field. Western blot and flow cytometry were used to assess the NIS expression level. Radioactivity counts of [¹⁸F]TFB, in vitro, in the three tumor cells were substantially higher than those in the KI inhibition group in the uptake experiment. In vivo PET imaging clearly delineated the three tumors based on the specific accumulation of [¹⁸F]TFB in a mouse model. Ex vivo biodistribution investigation showed high [¹⁸F]TFB absorption in the tumor location, which was consistent with the PET imaging results. These results support the use of NIS-transfected lung cell line A549 and NIS-expressing tumor cells MKN45 and K1, to investigate probing capabilities of [¹⁸F]TFB. We also demonstrate, for the first time, the feasibility of [¹⁸F]TFB in diagnosing stomach cancer. In conclusion, this study illustrates the promising future of [¹⁸F]TFB for tumor diagnosis and NIS reporter imaging.

Evaluating the Therapeutic Efficacy of Radiolabeled BSA@CuS Nanoparticle-induced Radio-photothermal Therapy against Anaplastic Thyroid Cancer

PURPOSE

Bovine serum albumin (BSA) has been employed as a mild biological template in nanoscale particles. Copper sulfide (CuS) has been used for photothermal therapy (PTT) in several studies. In this study, we aimed to synthesize the ¹³¹ I-labeled BSA-modified CuS nanoparticles (¹³¹ I-BSA@CuS), with attributes of both radiotherapy and PTT, as a therapeutic agent against anaplastic thyroid carcinoma (ATC).

METHOD

BSA@CuS nanoparticles were prepared using the solvothermal reaction and then labeled with Na¹³¹ I by the chloramine-T method. The products were characterized and their cytotoxicity was investigated in vitro and in vivo. The therapeutic efficacy of ¹³¹ I-BSA@CuS was evaluated in ARO cell (an ATC cell line) subcutaneous tumors.

RESULTS

The nanoparticles showed good biocompatibility and low toxicity in vitro and in vivo. BSA@CuS rapidly and effectively converted the light energy from an 808 nm laser into thermal energy with a conversion efficiency of 28.07%. SPECT/CT imaging demonstrated that the accumulation of radioactivity peaked within 24 h and resided in the tumors for 5 days post intratumoral injection. In vivo assays indicated that, compared to monotherapy, the synthesized nanoparticles employing both PTT and radiotherapy possess better therapeutic efficacy against tumors.

CONCLUSION

The synthesized nanomaterial showed uniform dispersion, good stability and aqueous solubility, excellent photothermal properties, and long-term retention in ATC. Hence, combined radiotherapy and PTT can significantly inhibit tumor growth compared to monotherapy, and can be applied in clinical settings.

Oncolytic virotherapy as promising immunotherapy against cancer: mechanisms of resistance to oncolytic viruses

Oncolytic virotherapy has currently emerged as a powerful therapeutic approach in cancer treatment. Although the history of using viruses goes back to the early 20th century, the approval of talimogene laherparepvec (T-VEC) in 2015 increased interest in oncolytic viruses (OVs). OVs are multifaceted biotherapeutic agents because they replicate in and kill tumor cells and augment immune responses by releasing immunostimulatory molecules from lysed cells. Despite promising results, some limitations hinder the efficacy of oncolytic virotherapy. The delivery challenges and the upregulation of checkpoints following oncolytic virotherapy also mediate resistance to OVs by diminishing immune responses. Furthermore, the localization of receptors of viruses in the tight junctions, interferon responses, and the aberrant expression of genes involved in the cell cycle of the virus, including their infection and replication, reduce the efficacy of OVs. In this review, we present different mechanisms of resistance to OVs and strategies to overcome them.

A review on the advances and challenges of immunotherapy for head and neck cancer

Head and neck cancer (HNC), which includes lip and oral cavity, larynx, nasopharynx, oropharynx, and hypopharynx malignancies, is one of the most common cancers worldwide. Due to the interaction of tumor cells with immune cells in the tumor microenvironment, immunotherapy of HNCs, along with traditional treatments such as chemotherapy, radiotherapy, and surgery, has attracted much attention. Four main immunotherapy strategies in HNCs have been developed, including oncolytic viruses, monoclonal antibodies, chimeric antigen receptor T cells (CAR-T cells), and therapeutic vaccines. Oncorine (H101), an approved oncolytic adenovirus in China, is the pioneer of immunotherapy for the treatment of HNCs. Pembrolizumab and nivolumab are mAbs against PD-L1 that have been approved for recurrent and metastatic HNC patients. To date, several clinical trials using immunotherapy agents and their combination are under investigation. In this review, we summarize current the interaction of tumor cells with immune cells in the tumor microenvironment of HNCs, the main strategies that have been applied for immunotherapy of HNCs, obstacles that hinder the success of immunotherapies in patients with HNCs, as well as solutions for overcoming the challenges to enhance the response of HNCs to immunotherapies.

Cancer imaging and therapy utilizing a novel NIS-expressing adenovirus: The role of adenovirus death protein deletion

Encoding the sodium iodide symporter (NIS) by an adenovirus (Ad) is a promising strategy to facilitate non-invasive imaging and radiotherapy of pancreatic cancer. However, insufficient levels of NIS expression in tumor cells have limited its clinical translation. To optimize Ad-based radiotherapy and imaging, we investigated the effect of Ad death protein (ADP) deletion on NIS expression. We cloned two sets of oncolytic NIS-expressing Ads that differed only in the presence or absence of ADP. We found that ADP expression negatively affected NIS membrane localization and inhibited radiotracer uptake. ADP deletion significantly improved NIS-based imaging in pancreatic cancer models including patient-derived xenografts, where effective imaging was possible for up to 6 weeks after a single virus injection. This study demonstrates that improved oncolysis may hinder the therapeutic effect of oncolytic viruses designed to express NIS. In vivo studies in combination with ¹³¹I showed potential for effective radiotherapy. This also highlights the need for further investigation into optimal timing of ¹³¹I administration and suggests that repeated doses of ¹³¹I should be considered to improve efficacy in clinical trials. We conclude that ADP deletion is essential for effective NIS-based theranostics in cancer.

Esophageal 99mTc-pertechnetate uptake mimicking an autonomous thyroid adenoma in a patient with subacute thyroiditis: a case report

Subacute thyroiditis (SAT) is one of the most common causes of thyrotoxicosis. Thyroid scans with radioiodine or technetium-99m pertechnetate (99mTc) are often performed in the workup of patients with thyrotoxicosis, particularly to differentiate between SAT and Graves’s disease. Although very helpful, thyroid scans are prone to pitfalls that may occasionally lead to misdiagnosis. These pitfalls are largely related to physiologic uptake of radioiodine or 99mTc in non-thyroidal tissue, such as salivary gland and stomach that may result in false-positive findings. We present herein a very rare case of SAT misdiagnosed as an autonomous thyroid adenoma most likely due to focal 99mTc uptake in the esophagus. This case may have implications for the management of patients with suspected SAT, who undergo a radioiodine or 99mTc thyroid scan.

A Novel Tyrosine Kinase Inhibitor Can Augment Radioactive Iodine Uptake Through Endogenous Sodium/Iodide Symporter Expression in Anaplastic Thyroid Cancer

Background: Radioactive iodine (RAI) therapy is an important strategy in the treatment of thyroid cancer. However, anaplastic thyroid cancer (ATC), a rare malignancy, exhibits severe dedifferentiation characteristics along with a lack of sodium iodide symporter (NIS) expression and function. Therefore, RAI therapy is ineffective and contributes toward poor prognosis of these patients. Recently, small-molecule tyrosine kinase inhibitors (TKIs) have been used to treat thyroid cancer patients for restoring NIS expression and function and RAI uptake capacity. However, most results reported thus far are associated with differentiated thyroid cancer. In this study, we identified a new TKI and investigated its effects on cell redifferentiation, NIS function, and RAI therapy in ATC. Methods: We identified a new TKI, "5-(5-{4H, 5H,6H-cyclopenta[b]thiophen-2-yl}-1,3,4-oxadiazol-2-yl)-1-methyl-1,2-dihydropyridin-2-one" (CTOM-DHP), using a high-throughput screening system. CTOM-DHP was exposed to 8505C ATC cells at different concentrations and time points. Concentrations of 12.5 and 25 μM and an incubation time of 72 hours were chosen as the conditions for subsequent NIS promoter assays and NIS mRNA and protein expression experiments. In addition, we examined factors related to iodide metabolism after CTOM-DHP treatment as well as the signaling pathways mediating the effects of CTOM-DHP on endogenous NIS expression. RAI uptake and ¹³¹I cytotoxicity effects caused by CTOM-DHP pretreatment were also evaluated in vitro and in vivo. Results: Promoter assays as well as mRNA and protein expression analyses confirmed that NIS expression was augmented by treatment of 8505C ATC cells with CTOM-DHP. Moreover, CTOM-DHP treatment robustly increased the expression of other thyroid-specific proteins and thyroid transcription factors related to iodide metabolism. Enhancement of NIS function was demonstrated by an increase in ¹²⁵I uptake and ¹³¹I cytotoxicity. Increased endogenous NIS expression was associated with the inhibition of PI3K/Akt and MAPK signaling pathways. In vivo results also demonstrated an increase in NIS promoter activity and RAI avidity in response to CTOM-DHP treatment. Furthermore, ¹³¹I-mediated therapeutic effects preferentially improved in a tumor xenograft mice model. Conclusions: CTOM-DHP, a new TKI identified in this study, enhances endogenous NIS expression and thereby is a promising compound for restoring RAI avidity in ATC.

A negative association between urinary iodine concentration and the prevalence of hyperuricemia and gout: a cross-sectional and population-based study in Mainland China

BACKGROUND AND AIMS

Iodine is one of the most important trace elements in the human body. It is not only the main component of thyroid hormones but also has extrathyroid biological functions. To date, there have been no large-scale epidemiological studies on the relationship between hyperuricemia and iodine intake, although both are closely related to health. A population-based epidemiological survey in China offers such an opportunity.

METHODS

This population-based cross-sectional study recruited 75,653 adults aged ≥ 18 years from 2015 to 2017 with a randomized, multistage, stratified sampling strategy. Serum uric acid levels and urinary iodine concentrations (UICs) were measured.

RESULTS

Stratified by UIC, the prevalence of hyperuricemia was 17.8%, 18.8%, 16.0% and 13.7% in the UIC < 100, 100-199, 200-299, and ≥ 300 μg/L groups, respectively; the prevalence of gout was 4.0%, 3.4%, 2.4% and 1.7%, respectively. The prevalence of gout decreased significantly as the UIC increased. The prevalence of hyperuricemia and gout were markedly higher in postmenopausal females than in the premenopausal population (hyperuricemia: 15.9% vs. 8.3%, X² = 520.072, p < 0.001; gout: 3.6% vs. 1.3%, X² = 219.889, p < 0.001), and the prevalence decreased as the UIC increased. Subjects in the more than adequate and excessive iodine groups had lower likelihoods of having hyperuricemia [aOR = 0.81 (95% CI 0.77-0.85), aOR = 0.68 (95% CI 0.64-0.72)] and lower odds of having gout than subjects in the adequate iodine (AI) group [aOR = 0.77 (95% CI 0.68-0.86), aOR = 0.59 (95% CI 0.51-0.68)].

CONCLUSIONS

UIC was inversely associated with the occurrence of hyperuricemia and gout. More in-depth research and prospective studies are needed to explore the molecular mechanisms and confirm the observed association.

Iodine‑131 metabolic radiotherapy leads to cell death and genomic alterations through NIS overexpression on cholangiocarcinoma

Cholangiocarcinoma (CC) is an aggressive liver tumor with limited therapeutic options. Natrium-iodide symporter (NIS) mediates the uptake of iodine by the thyroid, representing a key component in metabolic radiotherapy using iodine-131 (¹³¹I) for the treatment of thyroid cancer. NIS expression is increased in CC, providing the opportunity for a novel therapeutic approach for this type of tumor. Thus, in this study, we aimed to evaluate therapeutic efficacy of ¹³¹I in two human CC cell lines. Uptake experiments analyzed the ¹³¹I uptake profiles of the tumor cell lines under study. The cells were irradiated with various doses of ¹³¹I to evaluate and characterize the effects of metabolic radiotherapy. NIS protein expression was assessed by immunofluorescence methods. Cell survival was evaluated by clonogenic assay and flow cytometry was used to assess cell viability, and the type of death and alterations in the cell cycle. The genomic and epigenetic characterization of both CC cells was performed before and after irradiation. NIS gene expression was evaluated in the CC cells by RT-qPCR. The results revealed that CC cells had a higher expression of NIS. ¹³¹I induced a decrease in cell survival in a dose-dependent manner. With the increasing irradiation dose, a decrease in cell viability was observed, with a consequent increase in cell death by initial apoptosis. Karyotype and array comparative genomic hybridization (aCGH) analyses revealed that both CC cell lines were near-triploid with several numerical and structural chromosomal rearrangements. NIS gene expression was increased in the TFK-1 and HuCCT1 cells in a time-dependent manner. On the whole, the findings of this study demonstrate that the presence of NIS in cholangiocarcinoma cell lines is crucial for the decreased cell viability and survival observed following the exposure of cholangiocarcinoma cells to ¹³¹I.

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 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.

Dimerization of the Sodium/Iodide Symporter

Background: The ability of thyroid follicular epithelial cells to accumulate iodide via the sodium/iodide symporter (NIS) is exploited to successfully treat most thyroid cancers, although a subset of patients lose functional NIS activity and become unresponsive to radioiodide therapy, with poor clinical outcome. Our knowledge of NIS regulation remains limited, however. While numerous membrane proteins are functionally regulated via dimerization, there is little definitive evidence of NIS dimerization, and whether this might impact upon radioiodide uptake and treatment success is entirely unknown. We hypothesized that NIS dimerizes and that dimerization is a prerequisite for iodide uptake. Methods: Coimmunoprecipitation, proximity ligation, and Förster resonance energy transfer (FRET) assays were used to assess NIS:NIS interaction. To identify residues involved in dimerization, a homology model of NIS structure was built based on the crystal structure of the dimeric bacterial protein vSGLT. Results: Abundant cellular NIS dimerization was confirmed in vitro via three discrete methodologies. FRET and proximity ligation assays demonstrated that while NIS can exist as a dimer at the plasma membrane (PM), it is also apparent in other cellular compartments. Homology modeling revealed one key potential site of dimeric interaction, with six residues <3Å apart. In particular, NIS residues Y242, T243, and Q471 were identified as critical to dimerization. Individual mutation of residues Y242 and T243 rendered NIS nonfunctional, while abrogation of Q471 did not impact radioiodide uptake. FRET data show that the putative dimerization interface can tolerate the loss of one, but not two, of these three clustered residues. Conclusions: We show for the first time that NIS dimerizes in vitro, and we identify the key residues via which this happens. We hypothesize that dimerization of NIS is critical to its trafficking to the PM and may therefore represent a new mechanism that would need to be considered in overcoming therapeutic failure in patients with thyroid cancer.

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.

Radioactive Iodine-Refractory Differentiated Thyroid Cancer and Redifferentiation Therapy

The retained functionality of the sodium iodide symporter (NIS) expressed in differentiated thyroid cancer (DTC) cells allows the further utilization of post-surgical radioactive iodine (RAI) therapy, which is an effective treatment for reducing the risk of recurrence, and even the mortality, of DTC. Whereas, the dedifferentiation of DTC could influence the expression of functional NIS, thereby reducing the efficacy of RAI therapy in advanced DTC. Genetic alternations (such as BRAF and the rearranged during transfection [RET]/papillary thyroid cancer [PTC] rearrangement) have been widely reported to be prominently responsible for the onset, progression, and dedifferentiation of PTC, mainly through activating the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signaling cascades. These genetic alternations have been suggested to associate with the reduced expression of iodide-handling genes in thyroid cancer, especially the NIS gene, disabling iodine uptake and causing resistance to RAI therapy. Recently, novel and promising approaches aiming at various targets have been attempted to restore the expression of these iodine-metabolizing genes and enhance iodine uptake through in vitro studies and studies of RAI-refractory (RAIR)-DTC patients. In this review, we discuss the regulation of NIS, known mechanisms of dedifferentiation including the MAPK and PI3K pathways, and the current status of redifferentiation therapy for RAIR-DTC patients.

Biomolecules of 2-Thiouracil, 4-Thiouracil and 2,4-Dithiouracil: A DFT Study of the Hydration, Molecular Docking and Effect in DNA:RNAMicrohelixes

The molecular structure of 2-thiouracil, 4-thiouracil and 2,4-dithiouracil was analyzed under the effect of the first and second hydration shell by using the B3LYP density functional (DFT) method, and the results were compared to those obtained for the uracil molecule. A slight difference in the water distribution appears in these molecules. On the hydration of these molecules several trends in bond lengths and atomic charges were established. The ring in uracil molecule appears easier to be deformed and adapted to different environments as compared to that when it is thio-substituted. Molecular docking calculations of 2-thiouracil against three different pathogens: Bacillus subtilis, Escherichia coli and Candida albicans were carried out. Docking calculations of 2,4-dithiouracil ligand with various targeted proteins were also performed. Different DNA: RNA hybrid microhelixes with uridine, 2-thiouridine, 4-thiouridine and 2,4-dithiouridine nucleosides were optimized in a simple model with three nucleotide base pairs. Two main types of microhelixes were analyzed in detail depending on the intramolecular H-bond of the 2'-OH group. The weaker Watson-Crick (WC) base pair formed with thio-substituted uracil than with unsubstituted ones slightly deforms the helical and backbone parameters, especially with 2,4-dithiouridine. However, the thio-substitution significantly increases the dipole moment of the A-type microhelixes, as well as the rise and propeller twist parameters.

Rhenium-188 Labeled Radiopharmaceuticals: Current Clinical Applications in Oncology and Promising Perspectives

Rhenium-188 (¹⁸⁸Re) is a high energy beta-emitting radioisotope with a short 16.9 h physical half-life, which has been shown to be a very attractive candidate for use in therapeutic nuclear medicine. The high beta emission has an average energy of 784 keV and a maximum energy of 2.12 MeV, sufficient to penetrate and destroy targeted abnormal tissues. In addition, the low-abundant gamma emission of 155 keV (15%) is efficient for imaging and for dosimetric calculations. These key characteristics identify ¹⁸⁸Re as an important therapeutic radioisotope for routine clinical use. Moreover, the highly reproducible on-demand availability of ¹⁸⁸Re from the ¹⁸⁸W/¹⁸⁸Re generator system is an important feature and permits installation in hospital-based or central radiopharmacies for cost-effective availability of no-carrier-added (NCA) ¹⁸⁸Re. Rhenium-188 and technetium-99 m exhibit similar chemical properties and represent a “theranostic pair.” Thus, preparation and targeting of ¹⁸⁸Re agents for therapy is similar to imaging agents prepared with ^99mTc, the most commonly used diagnostic radionuclide. Over the last three decades, radiopharmaceuticals based on ¹⁸⁸Re-labeled small molecules, including peptides, antibodies, Lipiodol and particulates have been reported. The successful application of these ¹⁸⁸Re-labeled therapeutic radiopharmaceuticals has been reported in multiple early phase clinical trials for the management of various primary tumors, bone metastasis, rheumatoid arthritis, and endocoronary interventions. This article reviews the use of ¹⁸⁸Re-radiopharmaceuticals which have been investigated in patients for cancer treatment, demonstrating that ¹⁸⁸Re represents a cost effective alternative for routine clinical use in comparison to more expensive and/or less readily available therapeutic radioisotopes.

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

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

A review on the mechanism of iodide metabolic dysfunction in differentiated thyroid cancer

The incidence of differentiated thyroid cancer (DTC) has been increasing rapidly worldwide, and the risk factors remain unclear. With the growing number of patients with DTC, the related issues have been gradually highlighted. ¹³¹Iodide (¹³¹I) is an important treatment for DTC and has the potential to reduce the risk of recurrence. ¹³¹I is also an effective treatment for distant metastases of thyroid carcinoma. However, iodide metabolism dysfunction in metastatic foci causes patients to lose the opportunity of ¹³¹I treatment. This article reviews the related mechanisms of iodide metabolism dysfunction in DTC cells and summarizes the clinical transformation progression.

Differentiated thyroid cancer theranostics: radioiodine and beyond

The term theranostics is the combination of a diagnostic tool that helps to define the right therapeutic tool for specific disease. It signifies the "we know which sites require treatment (diagnostic scan) and confirm that those sites have been treated (post-therapy scan)" demonstrating the achievable tumor dose concept. This term was first used by John Funkhouser at the beginning of the 90s, at the same time the concept of personalized medicine appeared. In nuclear medicine, theranostics is easy to apply and understand because of an easy switch from diagnosis to therapy with the same vector. It helps in maximizing tumor dose and sparing normal tissue with high specific and rapid uptake in metastasis. The oldest application of this concept is radioactive iodine I-131 (RAI). The first treatment based on the theranostic concept was performed on thyroid cancer patients with RAI in 1946. From then on management of differentiated thyroid cancer (DTC) has evolved on the multimodality concept. We now use the term "our" patient instead of "my" patient to signify this. However, the initial surgical management followed by RAI as per the theranostics has remained the mainstay in achieving a cure in most of DTC patients. The normal thyroid cells metabolise iodine, the principle of which is utilized in imaging of the thyroid gland with isotopes of iodine. RAI treatment of DTC is based on the principle of sodium iodide symporter (NIS) expressing thyroid cells with DTC cells having the ability of trapping circulating RAI successfully helping in treatment of residual and metastatic disease. NIS is usually negative in poorly differentiated cells and is inversely proportional to Glucose transporter receptor Type 1 expression. Both positive and negative NIS are the key components of the theranostic approach in treatment of DTC. Presence or absence of NIS is documented by either whole body iodine scintigraphy (WBS) or 2-deoxy-2(¹⁸F) fludeoxyglucose (FDG) positron emission tomography computed tomography (PET-CT). Currently, single photon emission CT and CT (SPECT-CT) has significantly improved the precision and sensitivity of whole body iodine scintigraphy with its capability of accurate localization of disease foci whether iodine avid or non-avid. This has helped in a more personalized approach in treatment. This review will give an overview of the role of NIS in the theranostic approach to management with RAI, its current status and also the molecular approach to treatment in RAI refractory disease.

Bone Marrow-Derived Mesenchymal Stem Cell-Mediated Dual-Gene Therapy for Glioblastoma

Bone-marrow mesenchymal stem cells (BMSCs) have been used for systemic delivery of therapeutic genes to solid tumors. However, the optimal treatment time post-BMSC implantation and the assessment of the long-term fate of therapeutic BMSCs post-tumor treatment are critical if such promising therapies are to be translated into clinical practice. An efficient BMSC-based therapeutic strategy has been developed that simultaneously allows killing of tumor cells, inhibiting of tumor angiogenesis, and assessment and eradication of implanted BMSCs after treatment of glioblastoma. BMSCs were engineered to co-express the angiogenesis inhibitor kringle 5 (K5) of human plasminogen, under the control of the cytomegalovirus promoter (CMV) and the human sodium-iodide symporter (NIS), involved in uptake of radioisotopes, under the control of early growth response factor 1 (Egr1), a radiation-activated promoter. A significant decrease in tumor growth and tumor angiogenesis and a subsequent increase in survival were observed when mice bearing glioblastoma were treated with ¹⁸⁸Re post-therapeutic intravenous BMSC implantation. Furthermore, the systemic administration of ¹⁸⁸Re post-tumor treatment selectively eliminated therapeutic BMSCs expressing NIS, which was monitored in real time by ¹²⁵I micro single photon emission computed tomography/computed tomography imaging. Meanwhile, the Egr1 promoter induced a ¹⁸⁸Re radiation positive feedback effect absorbed by NIS. After intravenous BMSC implantation, BMSCs levels in the tumor and lung both peaked on day 10 and decreased to the lowest levels on days 24 and 17, respectively. These findings suggest that day 17 post-BMSC implantation could be an optimal time for ¹⁸⁸Re treatment. These results provide a new adjuvant therapy mediated by BMSCs for glioblastoma treatment.

A false-positive I-131 finding of duodenum diverticulum in thyroid cancer evaluation by SPECT/CT: A case report

RATIONALE

Iodine-131 (I-131) is a sensitive marker for the detection of differentiated thyroid cancer (DTC). I-131 whole-body scintigraphy (WBS) has been used widely in evaluation of DTC patient. However, I-131 WBS exists many false-positive uptake of I-131 because radioiodine uptake can also be seen in healthy tissue or in a variety of benign and malignant non-thyroidal tumors.

PATIENT CONCERNS

A 44-year-old woman with a papillary thyroid carcinoma for the purpose of ablation therapy after a total thyroidectomy. I-131 WBS showed intensive uptake by thyroid remnant. Meanwhile, a focus of increased activity was seen in right upper abdomen.

DISGNOSES, INTERVENTIONS AND OUTCOMES

Based on an I-131 single-photon emission computed tomography/computed tomography (SPECT/CT) fusion imaging combining a Tc-99m pertechnetate dynamic SPECT scan and SPECT/CT fusion imaging with oral administration of iodine contrast agent, a descending duodenum diverticulum was diagnosed. This patient was then treated with conservative treatment, such as diet regulation, rest, appropriate use of antacids and antispasmodic agents, etc. So far, she recovered uneventfully with no any complications.

LESSONS

Duodenum diverticulum is a rare false-positive uptake of I-131, it might be a diagnostic challenge when there are many false-positive uptake of I-131 in evaluation of DTC. So it must be significant to be familiar with these physiologic and pathologic variants of I-131 uptake and make further efforts to accurately interpret radioiodine scintigraphy results.

NIS expression in thyroid tumors, relation with prognosis clinicopathological and molecular features

Thyroid cancer therapy is based on surgery followed by radioiodine treatment. The incorporation of radioiodine by cancer cells is mediated by sodium iodide symporter (NIS) (codified by the SLC5A5 gene), that is functional only when targeted to the cell membrane. We aimed to evaluate if NIS expression in thyroid primary tumors would be helpful in predicting tumor behavior, response to therapy and prognosis. NIS expression was addressed by qPCR and immunohistochemistry. In order to validate our data, we also studied SLC5A5 expression on 378 primary papillary thyroid carcinomas from The Cancer Genome Atlas (TCGA) database. In our series, SLC5A5 expression was lower in carcinomas with vascular invasion and with extrathyroidal extension and in those harboring BRAFV600E mutation. Analysis of SLC5A5 expression from TCGA database confirmed our results. Furthermore, it showed that larger tumors, with locoregional recurrences and/or distant metastases or harboring RAS, BRAF and/or TERT promoter (TERTp) mutations presented significantly less SLC5A5 expression. Regarding immunohistochemistry, 12/211 of the cases demonstrated NIS in the membrane of tumor cells, those cases showed variable outcomes concerning therapy success, prognosis and all but one were wild type for BRAF, NRAS and TERTp mutations. SLC5A5 mRNA lower expression is associated with features of aggressiveness and with key genetic alterations involving BRAF, RAS and TERTp. Mutations in these genes seem to decrease protein expression and its targeting to the cell membrane. SLC5A5 mRNA expression is more informative than NIS immunohistochemical expression regarding tumor aggressiveness and prognostic features.

Pictorial Review of False-Positive Results on Radioiodine Scintigrams of Patients with Differentiated Thyroid Cancer

Radioiodine has served an important role in the diagnostic workup and treatment of patients with differentiated thyroid cancer for more than 6 decades. The interpretation of radioiodine scintigraphic studies should be performed in conjunction with a comprehensive history, histopathologic correlation, and pertinent laboratory values, as well as correlation with available anatomic images and the findings from physical examination. A thorough understanding of the physiology and biodistribution of radioiodine is critical when interpreting radioiodine scintigraphic studies to avoid misinterpretation of physiologic and nonthyroid pathologic variants as thyroid cancer metastases. Differentiating a false-positive finding from a true metastasis on pretherapy radioiodine scintigrams is important to determine the appropriate radioiodine treatment dose. The correct interpretation of posttherapy radioiodine scintigraphic studies is also important to determine if repeat radioiodine treatment will be necessary and for the future clinical and imaging followup of the patient. A variety of different factors, such as the presence of the sodium-iodide symporter and the passive diffusion or retention of radioiodine in normal and pathologic structures, can result in false-positive results on radioiodine scintigrams. Numerous false-positive findings have been reported in the literature and are further demonstrated with the increasing availability of single photon emission computed tomography (SPECT) integrated with computed tomography (CT) as true dual-modality imaging (SPECT/CT). SPECT/CT has been documented to be of incremental value in the accurate anatomic localization and characterization of radioiodine uptake as false-positive findings, particularly in cases with discordant findings of a low serum thyroglobulin level but positive findings on radioiodine whole-body planar scintigrams. The objectives of this review are to describe the physiology and biodistribution of radioiodine and to provide examples of false-positive results on radioiodine scintigrams, with clinical and anatomic correlation, in the following categories of radioiodine uptake: functional uptake secondary to sodium-iodide symporter expression, radioiodine retention, nonthyroid neoplasms, inflammatory or infectious uptake, contamination, and other causes. ^©RSNA, 2017.

Genetically Engineered Vaccinia Viruses As Agents for Cancer Treatment, Imaging, and Transgene Delivery

Despite advances in technology, the formidable challenge of treating cancer, especially if advanced, still remains with no significant improvement in survival rates, even with the most common forms of cancer. Oncolytic viral therapies have shown great promise for the treatment of various cancers, with the possible advantages of stronger treatment efficacy compared to conventional therapy due to higher tumor selectivity, and less toxicity. They are able to preferentially and selectively propagate in cancer cells, consequently destroying tumor tissue mainly via cell lysis, while leaving non-cancerous tissues unharmed. Several wild-type and genetically engineered vaccinia virus (VACV) strains have been tested in both preclinical and clinical trials with promising results. Greater understanding and advancements in molecular biology have enabled the generation of genetically engineered oncolytic viruses for safer and more efficacious treatment, including arming VACVs with cytokines and immunostimulatory molecules, anti-angiogenic agents, and enzyme prodrug therapy, in addition to combining VACVs with conventional external and systemic radiotherapy, chemotherapy, immunotherapy, and other virus strains. Furthermore, novel oncolytic vaccinia virus strains have been generated that express reporter genes for the tracking and imaging of viral therapy and monitoring of therapeutic response. Further study is needed to unlock VACVs’ full potential as part of the future of cancer therapy.

Effects of Long-Term In Vivo Exposure to Di-2-Ethylhexylphthalate on Thyroid Hormones and the TSH/TSHR Signaling Pathways in Wistar Rats

Di-(2-ethylhexyl)phthalate (DEHP) was a widely used chemical with human toxicity. Recent in vivo and in vitro studies suggested that DEHP-exposure may be associated with altered serum thyroid hormones (THs) levels, but the underlying molecular mechanisms were largely unknown. To explore the possible molecular mechanisms, 128 Wistar rats were dosed with DEHP by gavage at 0, 150, 300, and 600 mg/kg/day for 3 months (M) and 6 M, respectively. After exposure, expression of genes and proteins in the thyroid, pituitary, and hypothalamus tissues of rats were analyzed by Q-PCR and western blot, while the sera and urine samples were assayed by radioimmunoassay and ELISA. Results showed that serum THs levels were suppressed by DEHP on the whole. DEHP treatment influenced the levels of rats’ thyrotropin releasing hormone receptor (TRHr), Deiodinases 1 (D1), thyroid stimulating hormone beta (TSHβ), sodium iodide symporter (NIS), thyroid stimulating hormone receptor (TSHr), thyroperoxidase (TPO), thyroid transcription factor 1 (TTF-1), and thyroglobulin (TG) mRNA/protein expression in the hypothalamus-pituitary-thyroid (HPT) axis and decreased urine iodine. Taken together, observed findings indicate that DEHP could reduce thyroid hormones via disturbing the HPT axis, and the activated TSH/TSHR pathway is required to regulate thyroid function via altering TRHr, TSHβ, NIS, TSHr, TPO, TTF-1 and TG mRNA/protein expression of the HPT axis.

Longitudinal Assessment of Lung Cancer Progression in Mice Using the Sodium Iodide Symporter Reporter Gene and SPECT/CT Imaging

Lung cancer has the highest mortality rate of any tissue-specific cancer in both men and women. Research continues to investigate novel drugs and therapies to mitigate poor treatment efficacy, but the lack of a good descriptive lung cancer animal model for preclinical drug evaluation remains an obstacle. Here we describe the development of an orthotopic lung cancer animal model which utilizes the human sodium iodide symporter gene (hNIS; SLC5A5) as an imaging reporter gene for the purpose of non-invasive, longitudinal tumor quantification. hNIS is a glycoprotein that naturally transports iodide (I-) into thyroid cells and has the ability to symport the radiotracer 99mTc-pertechnetate (99mTcO4-). A549 lung adenocarcinoma cells were genetically modified with plasmid or lentiviral vectors to express hNIS. Modified cells were implanted into athymic nude mice to develop two tumor models: a subcutaneous and an orthotopic xenograft tumor model. Tumor progression was longitudinally imaged using SPECT/CT and quantified by SPECT voxel analysis. hNIS expression in lung tumors was analyzed by quantitative real-time PCR. Additionally, hematoxylin and eosin staining and visual inspection of pulmonary tumors was performed. We observed that lentiviral transduction provided enhanced and stable hNIS expression in A549 cells. Furthermore, 99mTcO4- uptake and accumulation was observed within lung tumors allowing for imaging and quantification of tumor mass at two-time points. This study illustrates the development of an orthotopic lung cancer model that can be longitudinally imaged throughout the experimental timeline thus avoiding inter-animal variability and leading to a reduction in total animal numbers. Furthermore, our orthotopic lung cancer animal model is clinically relevant and the genetic modification of cells for SPECT/CT imaging can be translated to other tissue-specific tumor animal models.

[(18)F]tetrafluoroborate as a PET tracer for the sodium/iodide symporter: the importance of specific activity

BACKGROUND

[(18)F]BF4 (-), the first (18)F-labelled PET imaging agent for the sodium/iodide symporter (NIS), was produced by isotopic exchange yielding a product with limited specific activity (SA, ca. 1 GBq/μmol) posing a risk of sub-optimal target-to-background ratios (TBR) in PET images due to saturation of NIS in vivo. We sought to quantify this risk and to develop a method of production of [(18)F]BF4 (-) with higher SA.

METHODS

A new radiosynthesis of [(18)F]BF4 (-) was developed, involving reaction of [(18)F]F(-) with boron trifluoride diethyl etherate under anhydrous conditions, guided by (11)B and (19)F NMR studies of equilibria involving BF4 (-) and BF3. The SA of the product was determined by ion chromatography. The IC50 of [(19)F]BF4 (-) as an inhibitor of [(18)F]BF4 (-) uptake was determined in vitro using HCT116-C19 human colon cancer cells expressing the human form of NIS (hNIS). The influence of [(19)F]BF4 (-) dose on biodistribution in vivo was evaluated in normal mice by nanoPET imaging and ex vivo tissue counting.

RESULTS

An IC50 of 4.8 μΜ was found in vitro indicating a significant risk of in vivo NIS saturation at SA achieved by the isotopic exchange labelling method. In vivo thyroid and salivary gland uptake decreased significantly with [(19)F]BF4 (-) doses above ca. 10 μg/kg. The new radiosynthesis gave high radiochemical purity (>99 %) and moderate yield (15 %) and improved SA (>5 GBq/μmol) from a starting activity of only 1.5 GBq.

CONCLUSIONS

[(18)F]BF4 (-) produced at previously reported levels of SA (1 GBq/μmol) can lead to reduced uptake in NIS-expressing tissues in mice. This is much less likely in humans. The synthetic approach described provides an alternative for production of [(18)F]BF4 (-) at higher SA with sufficient yield and without need for unusually high starting activity of [(18)F]fluoride, removing the risk of NIS saturation in vivo even in mice.

TRIAL REGISTRATION

ISRCTN75827286 .

Variants and pitfalls on radioiodine scans in pediatric patients with differentiated thyroid carcinoma

BACKGROUND

Potentially false-positive findings on radioiodine scans in children with differentiated thyroid carcinoma can mimic functioning thyroid tissue and functioning thyroid carcinomatous tissue. Such false-positive findings comprise variants and pitfalls that can vary slightly in children as compared with adults.

OBJECTIVE

To determine the patterns and frequency of these potential false-positive findings on radioiodine scans in children with differentiated thyroid carcinoma.

MATERIALS AND METHODS

We reviewed a total of 223 radioiodine scans from 53 pediatric patients (mean age 13.3 years, 37 girls) with differentiated thyroid carcinoma. Focal or regional activity that likely did not represent functioning thyroid tissue or functioning thyroid carcinomatous tissue were categorized as variants or pitfalls. The final diagnosis was confirmed by reviewing the concurrent and follow-up clinical data, correlative ultrasonography, CT scanning, serum thyroglobulin and antithyroglobulin antibody levels. We calculated the frequency of these variants and pitfalls from diagnostic and post-therapy radioiodine scans.

RESULTS

The most common variant on the radioiodine scans was the thymic activity (24/223, 10.8%) followed by the cardiac activity (8/223, 3.6%). Salivary contamination and star artifact, caused by prominent thyroid remnant, were the most important observed pitfalls.

CONCLUSION

Variants and pitfalls that mimic functioning thyroid tissue or functioning thyroid carcinomatous tissue on radioiodine scan in children with differentiated thyroid carcinoma are not infrequent, but they decrease in frequency on successive radioiodine scans. Potential false-positive findings can be minimized with proper knowledge of the common variants and pitfalls in children and correlation with clinical, laboratory and imaging data.

Enhancing Expression of Functional Human Sodium Iodide Symporter and Somatostatin Receptor in Recombinant Oncolytic Vaccinia Virus for In Vivo Imaging of Tumors

Oncolytic virus (OV) therapy has emerged as a novel tool in our therapeutic arsenals for fighting cancer. As a live biologic agent, OV has the ability to target and selectively amplify at the tumor sites. We have reported that a vaccinia-based OV (Pexa-Vec) has shown good efficacy in preclinical models and in clinical trials. To give an additional tool to clinicians to allow both treatment of the tumor and improved visualization of tumor margins, we developed new viral-based platforms with 2 specific gene reporters.

METHODS

We incorporated the human sodium iodide symporter (hNIS) and the human somatostatin receptor 2 (hSSR2) in the vaccinia-based OV and tested viral constructs for their abilities to track and treat tumor development in vivo.

RESULTS

Early and high-level expression of hNIS is detrimental to the recombinant virus, leading to the aggregation of hNIS protein and early cell death. Putting hNIS under a late synthetic promoter allowed a higher functional expression of the protein and much stronger ¹²³I or ⁹⁹Tc uptake. In vivo, the hNIS-containing virus infected and amplified in the tumor site, showing a better efficacy than the parental virus. The hNIS expression at the tumor site allowed for the imaging of viral infection and tumor regression. Similarly, hSSR2-containing OV vaccinia infected and lysed cancer cells.

CONCLUSION

When tumor-bearing mice were given hNIS- and hSSR2-containing OV, ⁹⁹Tc and ¹¹¹In signals coalesced at the tumor, highlighting the power of using these viruses for tumor diagnosis and treatment.

Thyroid malignant neoplasm-associated biomarkers as targets for oncolytic virotherapy

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

Use of rhenium-188 for in vivo imaging and treatment of human cervical cancer cells transfected with lentivirus expressing sodium iodide symporter

Although survival rates for cervical cancer have improved, they need further improvement in patients with distant metastases. The sodium iodine symporter (NIS) gene has often been used in cancer therapy and imaging. We examined the therapeutic effects of rhenium-188 (188Re) in a cervical cancer xenograft model expressing the NIS gene under the control of the tumor-specific human telomerase reverse transcriptase (hTERT) promoter. We constructed two recombinant lentiviral vectors expressing enhanced green fluorescent protein (eGFP) or the NIS gene driven by the hTERT promoter. To determine the tumor-specific transcriptional activity of the hTERT promoter, the eGFP-expressing vector was stably transfected into tumor cells and normal cells. A cervical cancer HeLa cell line stably expressing NIS (HeLa-TERTNIS) was created and examined in a similar way. HeLa and HeLa-TERTNIS tumor xenografts were transplanted in nude mice, and in vivo 188Re distribution was measured using micro-SPECT/CT imaging. The therapeutic effects of 188Re were assessed over 21 days on the basis of tumor volume and the immunohistochemical findings of excised tumors. eGFP expression controlled by the hTERT promoter was substantially higher in the tumor cells than normal cells. Quantitative PCR and western blotting confirmed that HeLa-TERTNIS cells expressed high levels of NIS mRNA and protein, respectively. Further, 188Re uptake and accumulation were significantly higher in HeLa-TERTNIS cells and xenografts than HeLa cells and xenografts. In vitro and in vivo, 188Re significantly reduced the survival of HeLa-TERTNIS cells and inhibited the growth of HeLa-TERTNIS xenografts, respectively. Immunohistochemical staining showed that HeLa-TERTNIS xenograft tumors expressed higher levels of NIS and caspase-3 and lower levels of Ki-67 than HeLa xenograft tumors. Our findings indicated that hTERT promoter-driven expression of the NIS gene in HeLa cells led to 188Re uptake and therapeutic effects. Thus, NIS-based gene therapy and imaging using the hTERT promoter and 188Re may be possible.

Linking loss of sodium-iodide symporter expression to DNA damage

Radiotherapy of thyroid cancer with I-131 is abrogated by inherent loss of radioiodine uptake due to loss of sodium iodide symporter (NIS) expression in poorly differentiated tumor cells. It is also known that ionizing radiation per se down-regulates NIS (the stunning effect), but the mechanism is unknown. Here we investigated whether loss of NIS-mediated iodide transport may be elicited by DNA damage. Calicheamicin, a fungal toxin that specifically cleaves double-stranded DNA, induced a full scale DNA damage response mediated by the ataxia-telangiectasia mutated (ATM) kinase in quiescent normal thyrocytes. At sublethal concentrations (<1nM) calicheamicin blocked NIS mRNA expression and transepithelial iodide transport as stimulated by thyrotropin; loss of function occurred at a much faster rate than after I-131 irradiation. KU-55933, a selective ATM kinase inhibitor, partly rescued NIS expression and iodide transport in DNA-damaged cells. Prolonged ATM inhibition in healthy cells also repressed NIS-mediated iodide transport. ATM-dependent loss of iodide transport was counteracted by IGF-1. Together, these findings indicate that NIS, the major iodide transporter of the thyroid gland, is susceptible to DNA damage involving ATM-mediated mechanisms. This uncovers novel means of poor radioiodine uptake in thyroid cells subjected to extrinsic or intrinsic genotoxic stress.

Signaling Pathways in Thyroid Cancer and Their Therapeutic Implications

Thyroid cancer is a common malignancy of endocrine system, and has now become the fastest increasing cancer among all the malignancies. The development, progression, invasion, and metastasis are closely associated with multiple signaling pathways and the functions of related molecules, such as Src, Janus kinase (JAK)-signal transducers and activators of transcription (STAT), mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/Akt, NF-κB, thyroid stimulating hormone receptor (TSHR), Wnt-β-catenin and Notch signaling pathways. Each of the signaling pathways could exert its function singly or through network with other pathways. These pathways could cooperate, promote, antagonize, or interact with each other to form a complex network for the regulation. Dysfunction of this network could increase the development, progression, invasion, and metastasis of thyroid cancer. Inoperable thyroid cancer still has a poor prognosis. However, signaling pathway-related targeted therapies offer the hope of longer quality of meaningful life for this small group of patients. Signaling pathway-related targets provide unprecedented opportunities for further research and clinical development of novel treatment strategies for this cancer. In the present work, the advances in these signaling pathways and targeted treatments of thyroid cancer were reviewed.

S-Nitrosylation of NF-κB p65 Inhibits TSH-Induced Na(+)/I(-) Symporter Expression

Nitric oxide (NO) is a ubiquitous signaling molecule involved in a wide variety of cellular physiological processes. In thyroid cells, NO-synthase III-endogenously produced NO reduces TSH-stimulated thyroid-specific gene expression, suggesting a potential autocrine role of NO in modulating thyroid function. Further studies indicate that NO induces thyroid dedifferentiation, because NO donors repress TSH-stimulated iodide (I(-)) uptake. Here, we investigated the molecular mechanism underlying the NO-inhibited Na(+)/I(-) symporter (NIS)-mediated I(-) uptake in thyroid cells. We showed that NO donors reduce I(-) uptake in a concentration-dependent manner, which correlates with decreased NIS protein expression. NO-reduced I(-) uptake results from transcriptional repression of NIS gene rather than posttranslational modifications reducing functional NIS expression at the plasma membrane. We observed that NO donors repress TSH-induced NIS gene expression by reducing the transcriptional activity of the nuclear factor-κB subunit p65. NO-promoted p65 S-nitrosylation reduces p65-mediated transactivation of the NIS promoter in response to TSH stimulation. Overall, our data are consistent with the notion that NO plays a role as an inhibitory signal to counterbalance TSH-stimulated nuclear factor-κB activation, thus modulating thyroid hormone biosynthesis.

Somatostatin activates Ras and ERK1/2 via a G protein βγ-subunit-initiated pathway in thyroid cells

Somatostatin (SST) is one of the main regulators of thyroid function. It acts by binding to its receptors, which lead to the dissociation of G proteins into Gαi and Gβγ subunits. However, much less is known about the function of Gβγ in thyroid cells. Here, we studied the role of SST and Gβγ dimers released upon SST stimulation on the Ras-ERK1/2 pathway in FTRL-5 thyroid cells. We demonstrate that SST activates Ras through Gi proteins, since SST-induced Ras activation is inhibited by pertussis toxin. Moreover, the specific sequestration of Gβγ dimers decreases Ras-GTP and phosphorylated ERK1/2 levels, and overexpression of Gβγ increases ERK1/2 phosphorylation induced by SST, indicating that Gβγ dimers released after SST treatment mediate activation of Ras and ERK1/2. On the other hand, SST treatment does not modify the expression of the thyroid differentiation marker sodium/iodide symporter (NIS) through ERK1/2 activation. However, SST increases AKT activation and the inhibition of the Src/PI3K/AKT pathway increases NIS levels in SST-treated cells. Thus, we conclude that, in thyroid cells, signalling from SST receptors to ERK1/2 involves a Gβγ-mediated signal acting on a Ras-dependent pathway. Moreover, we demonstrate that SST might regulates NIS expression through a Src/PI3K/AKT-dependent mechanism, but not through ERK1/2 signalling, showing the main role of this hormone in thyroid function.

The use of the NIS reporter gene for optimizing oncolytic virotherapy

Introduction: Oncolytic viruses are experimental cancer therapies being translated to the clinic. They are unique in their ability to amplify within the body, therefore requiring careful monitoring of viral replication and biodistribution. Traditional monitoring strategies fail to recapitulate the dynamic nature of oncolytic virotherapy. Consequently, clinically relevant, noninvasive, high resolution strategies are needed to effectively track virotherapy in real time.

Areas covered: The expression of the sodium iodide symporter (NIS) reporter gene is tightly coupled to viral genome replication and mediates radioisotope concentration, allowing noninvasive molecular nuclear imaging of active viral infection with high resolution. This provides insight into replication kinetics, biodistribution, the impact of vector design, administration, and dosing on therapeutic outcomes, and highlights the heterogeneity of spatial distribution and temporal evolution of infection. NIS-mediated imaging in clinical trials confirms the feasibility of this technology to noninvasively and longitudinally observe oncolytic virus infection, replication, and distribution.

Expert opinion: NIS-mediated imaging provides detailed functional and molecular information on the evolution of oncolytic virus infection in living animals. The use of NIS reporter gene imaging has rapidly advanced to provide unparalleled insight into the spatial and temporal context of oncolytic infection which will be integral to optimization of oncolytic treatment strategies.

Advances in the design and development of oncolytic measles viruses

A successful oncolytic virus is one that selectively propagates and destroys cancerous tissue without causing excessive damage to the normal surrounding tissue. Oncolytic measles virus (MV) is one such virus that exhibits this characteristic and thus has rapidly emerged as a potentially useful anticancer modality. Derivatives of the Edmonston MV vaccine strain possess a remarkable safety record in humans. Promising results in preclinical animal models and evidence of biological activity in early phase trials contribute to the enthusiasm. Genetic modifications have enabled MV to evolve from a vaccine agent to a potential anticancer therapy. Specifically, alterations of the MV genome have led to improved tumor selectivity and delivery, therapeutic potency, and immune system modulation. In this article, we will review the advancements that have been made in the design and development of MV that have led to its use as a cancer therapy. In addition, we will discuss the evidence supporting its use, as well as the challenges associated with MV as a potential cancer therapeutic.

Antisense-miR-21 enhances differentiation/apoptosis and reduces cancer stemness state on anaplastic thyroid cancer

Anaplastic thyroid carcinoma (ATC) is the most aggressive malignancy in thyroid cancers. Resistance to current therapies is still a challenge. MicroRNAs are a class of small non-coding RNAs, regulating gene expression. MiR-21 is an oncomiR that is overexpressed in nearly all cancers including ATC. Accumulating evidence suggested that miR-21 has a role in cancer stemness state, apoptosis, cell cycle progression, and differentiation. Therefore, we evaluated the application of Off-miR-21 to sequester the microRNA for therapeutic purposes on ATC cell lines. In this study, C643 and SW1736 were transducted by hsa-miR-21 antagomir (Off-miR-21). PTEN gene expression was performed as a known target of miR-21. Stemness state in cancer stem cells (CSCs) was evaluated by the changes of CSC biomarkers including Oct-4 and ABCG2. Apoptosis was assessed by PDCD4 and Mcl-1 gene expression and flow cytometry. Sodium/iodide symporter (NIS) and thyroglobulin (TG) were measured as ATC differentiation markers. In addition, cell cycle progression was investigated via the alterations of p21 gene expression and flow cytometry. Specific downregulation of miR-21 induced the differentiation and apoptosis in C643 and SW1736. Inversely, the treatment inhibited stemness state and cell cycle progression. Knockdown of miR-21 significantly increased the expression of PDCD4, p21, NIS, and TG while leading to decreased expression of Oct-4, ABCG2, and Mcl-1.Taken together, the results suggest that miR-21, as an oncomiR, has a role not only in stemness state but also in tumor growth, differentiation, and apoptosis. Hence, suppression of miR-21 could pave the way for ATC therapy.