Thyrotropin (TSH) suppression is required in the management of patients with papillary thyroid carcinoma (PTC) to improve their outcomes, inevitably causing iatrogenic thyrotoxicosis. Nevertheless, the evidence supporting this practice remains limited and weak, and in vitro studies examining the mitogenic effects of TSH in cancerous cells used supraphysiological doses of bovine TSH, which produced conflicting results. Our study explores, for the first time, the impact of human recombinant thyrotropin (rh-TSH) on human PTC cell lines (K1 and TPC-1) that were transformed to overexpress the thyrotropin receptor (TSHR). The cells were treated with escalating doses of rh-TSH under various conditions, such as the presence or absence of insulin. The expression levels of TSHR and thyroglobulin (Tg) were determined, and subsequently, the proliferation and migration of both transformed and non-transformed cells were assessed. Under the conditions employed, rh-TSH was not adequate to induce either the proliferation or the migration rate of the cells, while Tg expression was increased. Our experiments indicate that clinically relevant concentrations of rh-TSH cannot induce proliferation and migration in PTC cell lines, even after the overexpression of TSHR. Further research is warranted to dissect the underlying molecular mechanisms, and these results could translate into better management of treatment for PTC patients.

UNASSIGNED: Manifestations of thyroid-associated ophthalmopathy (TAO) vary greatly. Few tools and indicators are available to assess TAO, restricting personalized diagnosis and treatment.
UNASSIGNED: To identify an aptamer targeting thyroid-stimulating hormone receptor (TSHR) and utilize this aptamer to evaluate clinical activity in patients with TAO.
UNASSIGNED: An aptamer targeting TSHR was developed by exponential enrichment and systematic evaluation of TSHR ligands. After truncation and optimization, the affinity, equilibrium dissociation constant, and serum stability of this aptamer were evaluated. The affinity of the TSHR-targeting aptamer to isolated fibrocytes was assessed, as was aptamer internalization by fibrocytes. The mechanism of binding was determined by molecular docking. The correlation between disease manifestations and the percentage of TSHR-positive cells was assessed by correlation analysis.
UNASSIGNED: The aptamer TSHR-21-42 was developed to bind to TSHR, with the equilibrium dissociation constant being 71.46 Kd. Isolated fibrocytes were shown to bind TSHR-21-42 through TSHR, with its affinity maintained at various temperatures and ion concentrations. TSHR-21-42 could compete with anti-TSHR antibody, both for binding site to TSHR and uptake by cells after binding. In addition, TSHR-21-42 could bind to leukocytes in peripheral blood, with this binding differing in patients with TAO and healthy control subjects. The percentage of TSHR-positive monocytes, as determined by binding of TSHR-21-42, correlated positively with clinical activity score in patients with TAO, indicating that TSHR-21-42 binding could assess the severity of TAO.
UNASSIGNED: This aptamer targeting TSHR may be used to objectively assess disease activity in patients with TAO, by evaluating the percentages of TSHR positive cells in peripheral blood.

Graves\' disease is a type of autoimmune hyperthyroidism caused by thyroid-stimulating antibodies (TSAb).1 The combination of a porcine thyroid cell bioassay and cyclic adenosine monophosphate (cAMP) immunoassay (TSAb-enzyme immunoassay; EIA) is a clinically approved TSAb measurement method. Due to the requirement of multiple procedures and a long assay time of 6 h in the TSAb-EIA, a simplified and rapid assay is desired. Herein, we developed a rapid homogeneous TSAb bioassay (rapid-TSAb assay) using the human embryonic kidney cell line (HEK293), engineered to express the human thyroid-stimulating hormone receptor (TSHR), along with a cAMP-dependent luminescence biosensor. The measurement consists of three steps: thawing frozen cells, blood sample addition, and luminescence detection. The procedures can be conducted within 1 h. The World Health Organization International Standard TSAb (NIBSC 08/204) stimulated the cells co-expressing TSHR and cAMP biosensor. The intra- and inter-assay coefficients of variance were < 10%. Stimulation activity using wild-type TSHR and chimeric TSHR (Mc4) almost completely correlated with the tested Graves\' disease and normal samples. In the rapid-TSAb assay, the evaluation of 39 samples, including TSHR antibody-positive sera, yielded a sensitivity of 100.0% and a specificity of 90.9%, compared to the TSAb-EIA control. The rapid-TSAb assay enables simple and rapid measurement of TSAb and is promising for improving the diagnosis of autoimmune thyroid diseases.

UNASSIGNED: Genetic defects in the human thyroid-stimulating hormone (TSH) receptor (TSHR) gene can cause congenital hypothyroidism (CH). However, the biological functions and comprehensive genotype-phenotype relationships for most TSHR variants associated with CH remain unexplored. We aimed to identify TSHR variants in Chinese patients with CH, analyze the functions of the variants, and explore the relationships between TSHR genotypes and clinical phenotypes.
UNASSIGNED: In total, 367 patients with CH were recruited for TSHR variant screening using whole-exome sequencing. The effects of the variants were evaluated by in-silico programs such as SIFT and polyphen2. Furthermore, these variants were transfected into 293T cells to detect their Gs/cyclic AMP and Gq/11 signaling activity.
UNASSIGNED: Among the 367 patients with CH, 17 TSHR variants, including three novel variants, were identified in 45 patients, and 18 patients carried biallelic TSHR variants. In vitro experiments showed that 10 variants were associated with Gs/cyclic AMP and Gq/11 signaling pathway impairment to varying degrees. Patients with TSHR biallelic variants had lower serum TSH levels and higher free triiodothyronine and thyroxine levels at diagnosis than those with DUOX2 biallelic variants.
UNASSIGNED: We found a high frequency of TSHR variants in Chinese patients with CH (12.3%), and 4.9% of cases were caused by TSHR biallelic variants. Ten variants were identified as loss-of-function variants. The data suggest that the clinical phenotype of CH patients caused by TSHR biallelic variants is relatively mild. Our study expands the TSHR variant spectrum and provides further evidence for the elucidation of the genetic etiology of CH.

Research on modulation of iodine uptake by thyroid cells could help improve radioiodine treatment of dogs with thyroid tumors. The aim of this study was to characterize the immunohistochemical expression of thyroid transcription factor-1 (TTF-1), thyroglobulin, thyrotropin receptor (TSHR), sodium iodide symporter (NIS), pendrin, thyroid peroxidase (TPO), vimentin, and Ki-67 in follicular cell thyroid carcinomas (FTCs) and medullary thyroid carcinomas (MTCs), and to compare protein expression between FTC causing hyperthyroidism and FTC of euthyroid dogs. Immunohistochemistry was performed in 25 FTCs (9 follicular, 8 follicular-compact, and 8 compact) and 8 MTCs. FTCs and MTCs were positive for TTF-1, and expression was higher in FTCs of euthyroid dogs compared with FTCs of hyperthyroid dogs (P= .041). Immunolabeling for thyroglobulin was higher in follicular and follicular-compact FTCs compared with compact FTCs (P = .001), while vimentin expression was higher in follicular-compact FTCs compared with follicular FTCs (P = .011). The expression of TSHR, NIS, pendrin, and TPO was not significantly different among the different subtypes of FTCs or between FTCs causing hyperthyroidism and FTCs in euthyroid dogs. TSHR, NIS, pendrin, and TPO were also expressed in MTCs. Ki-67 labeling index was comparable between FTCs and MTCs, and between FTCs causing hyperthyroidism and FTCs in euthyroid dogs. Proteins of iodine transport were also expressed in canine MTCs, which could have implications for diagnosis and treatment. The different expression of thyroglobulin and vimentin between FTC histological subtypes could reflect variations in tumor differentiation.

Somatostatin receptor type 2 (SSTR2) and thyroid-stimulating hormone receptor (TSHR) display variable expression in primary thyroid tumors and have been implicated as theranostic targets. This study was designed to explore the differential expression of SSTR2 and TSHR in oncocytic (Hurthle cell) carcinoma (OC) vs oncocytic adenoma (OA). We performed a retrospective review for oncocytic neoplasms treated at our institution from 2012 to 2019. Formalin-fixed paraffin-embedded tissue blocks were used for tissue microarray construction. Tissue microarray blocks were cut into 5-μm sections and stained with anti-SSTR2 and anti-TSHR antibodies. Immunostains were analyzed by 3 independent pathologists. χ2 and logistic regression analysis were used to analyze clinical and pathologic variables. Sixty-seven specimens were analyzed with 15 OA and 52 OC. The mean age was 57 years, 61.2% were women, and 70% were White. SSTR2 positivity was noted in 2 OA (13%) and 15 OC (28%; 10 primary, 4 recurrent, and 1 metastatic) (P = .22). TSHR positivity was noted in 11 OA (73%) and 32 OC (62%; 31 primary and 1 metastatic) (P = .40). Those who presented with or developed clinical recurrence/metastasis were more likely to be SSTR2-positive (50% vs 21%; P = .04) and TSHR-negative (64.3% vs 28.9%; P = .02) than primary OC patients. Widely invasive OC was more likely to be SSTR2-positive compared to all other OC subtypes (minimally invasive and angioinvasive) (P = .003). For all patients with OC, TSHR positivity was inversely correlated with SSTR2 positivity (odds ratio, 0.12; CI, 0.03-0.43; P = .006). This relationship was not seen in the patients with OA (odds ratio, 0.30; CI, 0.01-9.14; P = .440). Our results show that recurrent/metastatic OC was more likely to be SSTR2-positive and TSHR-negative than primary OC. Patients with OC displayed a significant inverse relationship between SSTR2 and TSHR expression that was not seen in patients with OA. This may be a key relationship that can be used to prognosticate and treat OCs.

BACKGROUND: Recurrent and metastatic thyroid cancer is more invasive and can transform to dedifferentiated thyroid cancer, thus leading to a severe decline in the 10-year survival. The thyroid-stimulating hormone receptor (TSHR) plays an important role in differentiation process. We aim to find a therapeutic target in redifferentiation strategies for thyroid cancer.
METHODS: Our study integrated the differentially expressed genes acquired from the Gene Expression Omnibus database by comparing TSHR expression levels in the Cancer Genome Atlas database. We conducted functional enrichment analysis and verified the expression of these genes by RT-PCR in 68 pairs of thyroid tumor and paratumor tissues. Artificial intelligence-enabled virtual screening was combined with the VirtualFlow platform for deep docking.
RESULTS: We identified five genes (KCNJ16, SLC26A4, TG, TPO, and SYT1) as potential cancer treatment targets. TSHR and KCNJ16 were downregulated in the thyroid tumor tissues, compared with paired normal tissues. In addition, KCNJ16 was lower in the vascular/capsular invasion group. Enrichment analyses revealed that KCNJ16 may play a significant role in cell growth and differentiation. The inward rectifier potassium channel 5.1 (Kir5.1, encoded by KCNJ16) emerged as an interesting target in thyroid cancer. Artificial intelligence-facilitated molecular docking identified Z2087256678_2, Z2211139111_1, Z2211139111_2, and PV-000592319198_1 (-7.3 kcal/mol) as the most potent commercially available molecular targeting Kir5.1.
CONCLUSIONS: This study may provide greater insights into the differentiation features associated with TSHR expression in thyroid cancer, and Kir5.1 may be a potential therapeutic target in the redifferentiation strategies for recurrent and metastatic thyroid cancer.

Allosteric regulation is critical for the functioning of G protein-coupled receptors (GPCRs) and their signaling pathways. Endogenous allosteric regulators of GPCRs are simple ions, various biomolecules, and protein components of GPCR signaling (G proteins and β-arrestins). The stability and functional activity of GPCR complexes is also due to multicenter allosteric interactions between protomers. The complexity of allosteric effects caused by numerous regulators differing in structure, availability, and mechanisms of action predetermines the multiplicity and different topology of allosteric sites in GPCRs. These sites can be localized in extracellular loops; inside the transmembrane tunnel and in its upper and lower vestibules; in cytoplasmic loops; and on the outer, membrane-contacting surface of the transmembrane domain. They are involved in the regulation of basal and orthosteric agonist-stimulated receptor activity, biased agonism, GPCR-complex formation, and endocytosis. They are targets for a large number of synthetic allosteric regulators and modulators, including those constructed using molecular docking. The review is devoted to the principles and mechanisms of GPCRs allosteric regulation, the multiplicity of allosteric sites and their topology, and the endogenous and synthetic allosteric regulators, including autoantibodies and pepducins. The allosteric regulation of chemokine receptors, proteinase-activated receptors, thyroid-stimulating and luteinizing hormone receptors, and beta-adrenergic receptors are described in more detail.

UNASSIGNED: To investigate the expression of TSH receptors (TSHR) in various subtypes of Papillary thyroid carcinomas (PTC) by immunohistochemistry.
UNASSIGNED: Retrospective analyses were carried out to the clinical data of 108 PTC patients randomly admitted into the Department of Thyroidthyroid surgery thyroid surgery and Breast Surgery, The Second Hospital of Hebei Medical University from March 2020 to December 2020. The archived paraffin blocks of the 108 cases as well as 18 contiguous normal thyroid tissues (control group) were taken from the Department of Pathology of The Second Hospital of Hebei Medical University. The pathological types of all PTC tissues were detected and the expression of TSHR was determined.
UNASSIGNED: TSHR expression was 86.11% positive in PTC tissues; with 85.00% positive in classical group; with 75.86% positive in micro group; with 84.61% positive in follicular group; with 83.33% positive in oncocytic group; with 50.00% positive in invasive group. TSHR expression was 100% in normal thyroid tissues. So TSHR expression in normal thyroid tissues is significantly higher than that in PTC; TSHR expression in microcarcinoma is stronger than in the other subtypes; there is no significant difference among the other subtypes.
UNASSIGNED: TSH suppression works better on microcarcinoma than on the other subtypes. And the effects on non-invasive subtypes are better than on invasive subtypes.

The development of low-molecular-weight antagonists of thyroid-stimulating hormone (TSH) receptor is a promising trend in the treatment of autoimmune hyperthyroidism. We studied the effect of thieno[2,3-d]-pyrimidine derivative TPY1 on TSH-stimulated synthesis of thyroid hormones in the culture of FRTL-5 thyrocytes and on thyroliberin-stimulated production of thyroid hormones in rat blood. Preincubation of FRTL-5 cells with TPY1 suppressed the stimulatory effect of TSH on the synthesis of thyroxine and triiodothyronine. Intraperitoneal injection of TPY1 in a dose of 25 mg/kg reduced thyroliberin-stimulated levels of thyroid hormones in the blood and inhibited the expression of genes encoding thyroid peroxidase, thyroglobulin, and Na+/I- cotransporter responsible for thyroxine synthesis. In the absence of thyroliberin stimulation, TPY1 did not affect the levels of thyroid hormones and expression of thyroidogenesis genes. Thus, a new TPY1 antagonist of TSH receptor can be a prototype of a drug for the treatment of autoimmune hyperthyroidism.