Glucose transporters in the thyroid

Positron Emission Tomography/Computed Tomography in Thyroid Cancer: An Updated Review

PET/computed tomography (CT) is a valuable hybrid imaging modality for the evaluation of thyroid cancer, potentially impacting management decisions. 18F-fluorodeoxyglucose (FDG) PET/CT has proven utility for recurrence evaluation in differentiated thyroid cancer (DTC) patients having thyroglobulin elevation with negative iodine scintigraphy. Aggressive histologic subtypes such as anaplastic thyroid cancer shower higher FDG uptake. 18F-FDOPA is the preferred PET tracer for medullary thyroid cancer. Fibroblast activation protein inhibitor and arginylglycylaspartic acid -based radiotracers have emerged as promising PET agents for radioiodine refractory DTC patients with the potential for theranostic application.

Identification of SLC2A3 as a prognostic indicator correlated with the NF-κB/EMT axis and immune response in head and neck squamous cell carcinoma

SLC2A3 is an important member of the glucose transporter superfamily. It has been recently suggested that upregulation of SLC2A3 is associated with poor survival and acts as a prognostic marker in a variety of tumors. Unfortunately, the prognostic role of SLC2A3 in head and neck squamous cell carcinoma (HNSC) is less known. In the present study, we analyzed SLC2A3 expression in HNSC and its correlation with prognosis using TCGA and GEO databases. The results showed that SLC2A3 mRNA expression was higher in HNSC compared with adjacent normal tissues, which was validated with our 9 pairs of HNSC specimens. Moreover, high SLC2A3 expression predicted poor prognosis in HNSC patients. Mechanistically, GSEA revealed that high expression of SLC2A3 was enriched in epithelial-mesenchymal transition (EMT) and NF-κB signaling. In HNSC cell lines, SLC2A3 knockdown inhibited cell proliferation and migration. In addition, NF-κB P65 and EMT-related gene expression was suppressed upon SLC2A3 knockdown, indicating that SLC2A3 may play a preeminent role in the progression of HNSC through the NF-κB/EMT axis. Meanwhile, the expression of SLC2A3 was negatively correlated with immune cells, suggesting that SLC2A3 may be involved in the immune response in HNSC. The correlation between SLC2A3 expression and drug sensitivity was further assessed. In conclusion, our study demonstrated that SLC2A3 could predict the prognosis of HNSC patients and mediate the progression of HNSC via the NF-κB/EMT axis and immune responses.

Metabolic Reprogramming of Thyroid Cancer Cells and Crosstalk in Their Microenvironment

Metabolism differs significantly between tumor and normal cells. Metabolic reprogramming in cancer cells and metabolic interplay in the tumor microenvironment (TME) are important for tumor formation and progression. Tumor cells show changes in both catabolism and anabolism. Altered aerobic glycolysis, known as the Warburg effect, is a well-recognized characteristic of tumor cell energy metabolism. Compared with normal cells, tumor cells consume more glucose and glutamine. The enhanced anabolism in tumor cells includes de novo lipid synthesis as well as protein and nucleic acid synthesis. Although these forms of energy supply are uneconomical, they are required for the functioning of cancer cells, including those in thyroid cancer (TC). Increasing attention has recently focused on alterations of the TME. Understanding the metabolic changes governing the intricate relationship between TC cells and the TME may provide novel ideas for the treatment of TC.

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

Simple Summary

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

Abstract

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

Tunicamycin as a Novel Redifferentiation Agent in Radioiodine Therapy for Anaplastic Thyroid Cancer

The silencing of thyroid-related genes presents difficulties in radioiodine therapy for anaplastic thyroid cancers (ATCs). Tunicamycin (TM), an N-linked glycosylation inhibitor, is an anticancer drug. Herein, we investigated TM-induced restoration of responsiveness to radioiodine therapy in radioiodine refractory ATCs. ¹²⁵I uptake increased in TM-treated ATC cell lines, including BHT101 and CAL62, which was inhibited by KClO₄, a sodium-iodide symporter (NIS) inhibitor. TM upregulated the mRNA expression of iodide-handling genes and the protein expression of NIS. TM blocked pERK1/2 phosphorylation in both cell lines, but AKT (protein kinase B) phosphorylation was only observed in CAL62 cells. The downregulation of glucose transporter 1 protein was confirmed in TM-treated cells, with a significant reduction in ¹⁸F-fluorodeoxyglucose (FDG) uptake. A significant reduction in colony-forming ability and marked tumor growth inhibition were observed in the combination group. TM was revealed to possess a novel function as a redifferentiation inducer in ATC as it induces the restoration of iodide-handling gene expression and radioiodine avidity, thereby facilitating effective radioiodine therapy.

Physiological and Pathophysiological Roles of Ion Transporter-Mediated Metabolism in the Thyroid Gland and in Thyroid Cancer

Thyroid cancer is the most common type of endocrine tumor and has shown an increasing annual incidence, especially among women. Patients with thyroid cancer have a good prognosis, with a high five-year survival rate; however, the recurrence rate and disease status of thyroid cancer remain a burden for patients, which compels us to further elucidate the pathogenesis of this disease. Recently, ion transporters have gradually become a hot topic in the field of thyroid gland biology and cancer research. Additionally, alterations in the metabolic state of tumor cells and protein molecules have gradually become the focus of scientific research. This review focuses on the progress in understanding the physiological and pathophysiological roles of ion transporter-mediated metabolism in both the thyroid gland and thyroid cancer. We also hope to shed light on new targets for the treatment and prognosis of thyroid cancer.

Regulators of glucose uptake in thyroid cancer cell lines

Abstract

Thyroid cancer is the most common sort of endocrine-related cancer with more prevalent in women and elderly individuals which has quickly widespread expansion in worldwide over the recent decades. Common features of malignant thyroid cells are to have accelerated metabolism and increased glucose uptake to optimize their energy supply which provides a fundamental advantage for growth. In tumor cells the retaining of required energy charge for cell survival is imperative, indeed glucose transporters are enable of promoting of this task. According to this relation it has been reported the upregulation of glucose transporters in various types of cancers. Human studies indicated that poor survival can be occurred following the high levels of GLUT1 expression in tumors. GLUT-1 and GLUT3 are the glucose transporters which seems to be mainly engaged with the oncogenesis of thyroid cancer and their expression in malignant tissues is much more than in the normal one. They are promising targets for the advancement of anticancer strategies. The lack of oncosuppressors have dominant effect on the membrane expression of GLUT1 and glucose uptake. Overexpression of hypoxia inducible factors have been additionally connected with distant metastasis in thyroid cancers which mediates transcriptional regulation of glycolytic genes including GLUT1 and GLUT3. Though the physiological role of the thyroid gland is well illustrated, but the metabolic regulations in thyroid cancer remain evasive. In this study we discuss proliferation pathways of the key regulators and signaling molecules such as PI3K-Akt, HIF-1, MicroRNA, PTEN, AMPK, BRAF, c-Myc, TSH, Iodide and p53 which includes in the regulation of GLUTs in thyroid cancer cells. Incidence of deregulations in cellular energetics and metabolism are the most serious signs of cancers. In conclusion, understanding the mechanisms of glucose transportation in normal and pathologic thyroid tissues is critically important and could provide significant insights in science of diagnosis and treatment of thyroid disease.

A Novel Orally Active Inverse Agonist of Estrogen-related Receptor Gamma (ERRγ), DN200434, A Booster of NIS in Anaplastic Thyroid Cancer

PURPOSE

New strategies to restore sodium iodide symporter (NIS) expression and function in radioiodine therapy-refractive anaplastic thyroid cancers (ATCs) are urgently required. Recently, we reported the regulatory role of estrogen-related receptor gamma (ERRγ) in ATC cell NIS function. Herein, we identified DN200434 as a highly potent (functional IC₅₀ = 0.006 μmol/L), selective, and orally available ERRγ inverse agonist for NIS enhancement in ATC.

EXPERIMENTAL DESIGN

We sought to identify better ERRγ-targeting ligands and explored the crystal structure of ERRγ in complex with DN200434. After treating ATC cells with DN200434, the change in iodide-handling gene expression, as well as radioiodine avidity was examined. ATC tumor-bearing mice were orally administered with DN200434, followed by ¹²⁴I-positron emission tomography/CT (PET/CT). For radioiodine therapy, ATC tumor-bearing mice treated with DN200434 were administered ¹³¹I (beta ray-emitting therapeutic radioiodine) and then bioluminescent imaging was performed to monitor the therapeutic effects. Histologic analysis was performed to evaluate ERRγ expression status in normal tissue and ATC tissue, respectively.

RESULTS

DN200434-ERRγ complex crystallographic studies revealed that DN200434 binds to key ERRγ binding pocket residues through four-way interactions. DN200434 effectively upregulated iodide-handling genes and restored radioiodine avidity in ATC tumor lesions, as confirmed by ¹²⁴I-PET/CT. DN200434 enhanced ATC tumor radioiodine therapy susceptibility, markedly inhibiting tumor growth. Histologic findings of patients with ATC showed higher ERRγ expression in tumors than in normal tissue, supporting ERRγ as a therapeutic target for ATC.

CONCLUSIONS

DN200434 shows potential clinical applicability for diagnosis and treatment of ATC or other poorly differentiated thyroid cancers.

Clinical significance of patterns of increased [18F]-FDG uptake in the thyroid gland: a pictorial review

In the diagnosis and staging of oncologic patients, [¹⁸F]-fluorodeoxyglucose positron emission tomography (FDG-PET) is well recognized as an important functional imaging modality. FDG-PET also has been used for cancer screening in healthy individuals. In general, the normal thyroid gland shows absent or low uptake on FDG-PET, which is often identified as an incidental finding on PET. Today, thyroid FDG uptake can be seen in three patterns: diffuse; focal; and diffuse-plus-focal. Diffuse thyroid uptake is mainly considered an indicator of chronic thyroiditis. Focal thyroid uptake has been associated with malignancy (range 25-50%). Diffuse-plus-focal uptake is not well recognized and might also indicate a risk of malignancy. Understanding the patterns of thyroid FDG uptake is thus important for nuclear medicine physicians or radiologists when giving recommendations to the referring physician. In this pictorial review, we show the clinical significance of different patterns of thyroid uptake on FDG-PET [PET/computed tomography (CT)], including ultrasonography (US) findings.

Relationships between transporter expression and the status of BRAF V600E mutation and F-18 FDG uptake in papillary thyroid carcinomas

PURPOSE

The purpose of this study was to evaluate the expression of the glucose transporters GLUT1 and GLUT3 in papillary thyroid carcinomas (PTCs) and to elucidate their relationship with the BRAF V600E mutation and F-18 FDG uptake.

MATERIALS AND METHODS

We retrospectively analyzed data of 52 PTC patients (41 women and 11 men; mean age, 52.4 ± 14.5 years). F-18 FDG PET/CT was performed preoperatively, and the maximum standardized uptake value (SUVmax) was calculated. GLUT1/GLUT3 expression was determined immunohistochemically, and the BRAF V600E mutation was detected using DNA sequencing.

RESULTS

GLUT1 and GLUT3 were expressed in 82.7% (43/52) and 59.6% (31/52) PTCs, respectively. The BRAF V600E mutation was detected in 65.4% (34/52) PTCs. The odds ratio between GLUT1 expression and the BRAF V600E mutation was 5.2 (95% CI, 1.11-24.05; p < 0.05), and that between GLUT3 expression and the BRAF V600E mutation was 3.8 (95% CI, 1.14-12.53; p < 0.05). The SUVmax of PTCs was significantly higher if they carried the BRAF V600E mutation (11.3 ± 2.0, compared with 5.7 ± 1.4 for wild type BRAF tumors, Mann-Whitney test, p = 0.016). Neither GLUT1 nor GLUT3 expression was significantly associated with the SUVmax of F-18 FDG PET/CT in PTCs.

CONCLUSIONS

Our findings confirmed that both GLUT1 and GLUT3 are strongly expressed by PTCs, although their expression was not significantly associated with the SUVmax of F-18 FDG PET/CT. However, GLUT1 and GLUT3 expressions were significantly associated with the presence of the BRAF V600E mutation, and the SUVmax of tumors was significantly higher in the presence of the mutated BRAF gene.

No evidence for a decreased risk of thyroid cancer in association with use of metformin or other antidiabetic drugs: a case-control study

Background

Use of metformin has been associated with a decreased cancer risk. We aimed to explore whether use of metformin or other antidiabetic drugs is associated with a decreased risk for thyroid cancer.

Methods

We conducted a case-control analysis (1995 to 2014) using the U.K.-based Clinical Practice Research Datalink (CPRD). Cases had a first-time diagnosis of thyroid cancer, six controls per case were matched on age, sex, calendar time, general practice, and number of years of active history in the database prior to the index date. We assessed odds ratios (ORs) with 95 % confidence intervals (95 % CI), adjusted for body mass index (BMI), smoking, and diabetes mellitus.

Results

In 1229 cases and 7374 matched controls, the risk of thyroid cancer associated with ever use of metformin yielded an adjusted OR of 1.48, 95 % CI 0.86–2.54. The relative risk estimate was highest in long-term (≥30 prescriptions) users of metformin (adjusted OR 1.83, 95 % CI 0.92–3.65), based on a limited number of 26 exposed cases. No such association was found in users of sulfonylurea, insulin, or thiazolidinediones (TZD). Neither a diabetes diagnosis (adjusted OR 1.17, 95 % CI 0.89–1.54), nor diabetes duration >8 years (adjusted OR 1.22, 95 % CI 0.60–2.51) altered the risk of thyroid cancer.

Conclusion

In our observational study with limited statistical power, neither use of metformin nor of other antidiabetic drugs were associated with a decreased risk of thyroid cancer.

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

CONTEXT

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

OBJECTIVE

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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

PTEN regulates plasma membrane expression of glucose transporter 1 and glucose uptake in thyroid cancer cells

Glucose represents an important source of energy for the cells. Proliferating cancer cells consume elevated quantity of glucose, which is converted into lactate regardless of the presence of oxygen. This phenomenon, known as the Warburg effect, has been proven to be useful for imaging metabolically active tumours in cancer patients by (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET). Glucose is internalised in the cells by glucose transporters (GLUTs) belonging to the GLUT family. GLUT1 (SLC2A1) is the most prevalent isoform in more aggressive and less differentiated thyroid cancer histotypes. In a previous work, we found that loss of expression of PTEN was associated with increased expression of GLUT1 on the plasma membrane (PM) and probability of detecting thyroid incidentalomas by FDG-PET. Herein, we investigated the molecular pathways that govern the expression of GLUT1 on the PM and the glucose uptake in WRO (expressing WT PTEN) and FTC133 (PTEN null) follicular thyroid cancer cells cultured under glucose-depleted conditions. The membrane expression of GLUT1 was enhanced in glucose-deprived cells. Through genetic manipulations of PTEN expression, we could demonstrate that the lack of this oncosuppressor has a dominant effect on the membrane expression of GLUT1 and glucose uptake. We conclude that loss of function of PTEN increases the probability of cancer detection by FDG-PET or other glucose-based imaging diagnosis.

PTEN deficiency and mutant p53 confer glucose-addiction to thyroid cancer cells: impact of glucose depletion on cell proliferation, cell survival, autophagy and cell migration

Proliferating cancer cells oxidize glucose through the glycolytic pathway. Since this metabolism is less profitable in terms of ATP production, cancer cells consume large quantity of glucose, and those that experience insufficient blood supply become glucose-addicted. We have analyzed the response to glucose depletion in WRO and FTC133 follicular thyroid cancer cells, which differ in the expression of two key regulators of the glucose metabolism. WRO cells, which express wild type p53 and PTEN, showed a higher rate of cell proliferation and were much less sensitive to glucose-depletion than FTC133 cells, which are PTEN null and express mutant p53. Glucose depletion slowed-down the autophagy flux in FTC133 cells, not in WRO cells. In a wound-healing assay, WRO cells were shown to migrate faster than FTC133 cells. Glucose depletion slowed down the cell migration rate, and these effects were more evident in FTC133 cells. Genetic silencing of either wild-type PTEN or p53 in WRO cells resulted in increased uptake of glucose, whereas the ectopic expression of PTEN in FTC133 cells resulted in diminished glucose uptake. In conclusion, compared to WRO, FTC133 cells were higher glucose up-taker and consumer. These data do not support the general contention that cancer cells lacking PTEN or expressing the mutant p53R273H are more aggressive and prone to better face glucose depletion. We propose that concurrent PTEN deficiency and mutant p53 leads to a glucose-addiction state that renders the cancer cell more sensitive to glucose restriction. The present observation substantiates the view that glucose-restriction may be an adjuvant strategy to combat these tumours.

AMP-activated protein kinase upregulates glucose uptake in thyroid PCCL3 cells independent of thyrotropin

BACKGROUND

Glucose is transported into cells by specific glucose transporter proteins (GLUTs) that are widely expressed in a tissue-specific manner. The mechanisms that regulate glucose uptake and metabolism in thyroid cells are poorly defined. Recently, our group showed that AMP-activated protein kinase (AMPK) plays a pivotal role in the rat thyroid gland, downregulating iodide uptake by thyroid cells even in the presence of its main stimulator thyrotropin (TSH). Since AMPK increases glucose uptake in different tissues, and taken into consideration that in pathophysiological conditions such as thyroid cancer a negative correlation between iodide and glucose uptake occurs, we hypothesized that AMPK might modulate glucose uptake in thyroid cells.

METHODS

Rat follicular thyroid PCCL3 cells cultivated in Ham's F-12 supplemented with 5% calf serum and hormones were exposed to the AMPK pharmacological activator 5-aminoimidazole-4 carboxamide ribonucleoside (AICAR) or AMPK antagonist compound C for 24 hours either in the presence or absence of TSH. Glucose uptake was assessed in vitro using 2-deoxy-D-[(3)H]glucose.

RESULTS

AMPK activation by AICAR induced a significant increase in glucose uptake by PCCL3 cells, an effect that was completely reversed by the AMPK inhibitor compound C. Also, the AICAR mediated increase in glucose uptake was detected either in the presence or absence of TSH. The mechanism by which AICAR increases glucose uptake is related to higher levels of GLUT 1 protein content and hexokinase (HK) activity in thyroid cells.

CONCLUSION

Our results show that AMPK activation significantly upregulates GLUT 1 content and glucose uptake, and it also stimulates hexokinase activity, the first step of glycolysis.

Regulation of uptake of 18F-FDG by a follicular human thyroid cancer cell line with mutation-activated K-ras

Dedifferentiation of thyroid carcinoma is accompanied by increased accumulation of the PET tracer (18)F-FDG. The molecular mechanisms responsible for this phenomenon are poorly understood. Therefore, we studied the regulation of (18)F-FDG uptake by the human follicular thyroid carcinoma cell line ML-1 and the as-yet-unknown oncogene expression of that cell line. The data obtained in ML-1 were compared with those of a well-differentiated thyroid cell line of rat origin (FRTL-5).

METHODS

The expression of the thyroid-stimulating hormone (TSH) receptor was investigated by immunocytochemistry, and the expression of the glucose transporters (GLUTs) was determined by Western blotting. Mutation analysis of ML-1 was performed for K-ras codons 12 and 13. The effect of TSH on intracellular cAMP levels was determined by a competitive enzyme immunoassay. Cells were incubated with (18)F-FDG (0.5-1.0 MBq/mL) for 1 h, and tracer uptake was related to protein concentration. The effects of bovine TSH, the cAMP analog (Bu)(2)cAMP, and the phosphatidylinositol-3-kinase (PI3-kinase) inhibitor LY294002 on (18)F-FDG uptake were investigated.

RESULTS

The TSH receptor was present in both cell lines. FRTL-5 clearly expressed GLUT-1 and also GLUT-4. In ML-1 only, the expression of GLUT-3 was detected. TSH and (Bu)(2)cAMP had a significant effect on (18)F-FDG uptake or GLUT-1 expression in FRTL-5, but not in ML-1 cells. PI3-kinase inhibition by LY294002 downregulated (18)F-FDG uptake in FRTL-5 by 58% +/- 9% (n = 6) and in ML-1 by 26% +/- 5% (n = 42, both P < 0.05). Mutation analysis of ML-1 cells revealed a Gly12Ser point mutation at codon 12 of the K-ras gene.

CONCLUSION

(18)F-FDG uptake in the thyroid carcinoma cell line ML-1 is no longer regulated by TSH or cAMP or mediated by GLUT-1. However, in this cell line, this variable is still governed to some extent by PI3-kinase located downstream to the constitutively active K-ras in the Ras-PI3-kinase-Akt pathway. These data suggest that increases in (18)F-FDG uptake in thyroid carcinomas observed in vivo by PET may reflect activation of intracellular signal transduction cascades by oncogenes.

Reciprocal immunohistochemical expression of sodium/iodide symporter and hexokinase I in primary thyroid tumors with synchronous cervical metastasis

OBJECTIVES/HYPOTHESIS

Sodium/iodide symporter (NIS) is a glycoprotein which is related to the concentration of radioiodine in thyroid cancer. Glucose transporter-1 (Glut-1) and hexokinases (HK) are glycoproteins related to glucose metabolism (i.e., uptake and phosphorylation) in various cancers. The aim of this study was to determine the immunohistochemical patterns of expression and mutual relationships between NIS, Glut-1, HK I, and HK II in primary thyroid tumors and synchronous cervical metastatic tumors.

STUDY DESIGN

Retrospective experimental study.

METHODS

Nine cases of follicular carcinomas, sixteen cases of papillary carcinomas, and four cases of anaplastic carcinomas were included. The immunohistochemical staining intensities were categorized (scored) as negative (0), weak (1), positive (2), or strongly positive (3) and dichotomized as a negative/weak (scores 0 or 1) or positive expression (scores 2 or 3).

RESULTS

NIS had a positive expression in good prognostic types of thyroid carcinomas, such as follicular carcinomas, more often, while having a positive expression in poor prognostic types of thyroid carcinomas, such as anaplastic carcinomas (P = .033) less often; HK I had the opposite pattern of expression (P = .033). Primary thyroid tumors and corresponding synchronous cervical metastatic tumors had a similar pattern of expression for NIS, HK I, and HK II. NIS had a reciprocal relationship with HK I as compared to Glut-1 with respect to staining intensity on each primary tumor (P = .040).

CONCLUSION

Reciprocal staining pattern of NIS and HK I on primary tumors is related to the staining pattern of NIS and HK I on synchronous as well as occult cervical metastatic tumors.

Expression analysis of facilitative glucose transporters (GLUTs) in human thyroid carcinoma cell lines and primary tumors

Fluorine-18-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) is based on cell capability to take-up glucose. While a significantly higher expression of the glucose transporter GLUT1 has been reported in thyroid tumors only few data are available on the expression of other GLUT isoforms. We studied several GLUT isoforms expression in thyroid tumor cell lines deriving from anaplastic (ARO, FRO), papillary (NPA), follicular (WRO) and medullary (TT) human thyroid carcinoma. GLUT1 and GLUT3 were also studied in 157 human thyroid malignant and benign tissues. Quantitative Real-time RT-PCR analysis revealed that GLUT1 mRNA levels were higher in less-differentiated cells (ARO, FRO) while GLUT3 mRNA levels were prevalent in well-differentiated cells (NPA, WRO). Accordingly, Western blot showed high expression and correct membrane targeting of GLUT1 protein in ARO and FRO and of GLUT3 protein in NPA and WRO. All cell lines were able to take-up different rates of (3)H-deoxy-glucose. The analysis of GLUT1 and GLUT3 mRNA expression in human thyroid tissues showed the prevalence of GLUT1, but not of GLUT3, in malignant with respect to normal tissues. Finally, both GLUT1 and GLUT3 showed a slightly higher expression in anaplastic than in well-differentiated tumors. In conclusion, we showed that GLUT1 and GLUT3 were the most important glucose transporters in the thyroid tumoral cells. In particular GLUT1 was the most prevalent in less-differentiated cells (ARO and FRO) while GLUT3 was the most prevalent in well-differentiated cells (NPA and WRO). A similar pattern of expression was found for GLUT1 but not for GLUT3 in human thyroid tumors.

Molecular characteristics in papillary thyroid cancers (PTCs) with no 131I uptake

OBJECTIVE

Papillary thyroid cancers (PTCs) with no iodine uptake have an aggressive behaviour and a poor prognosis. The aim of our study was to characterize, at molecular level, a subset of PTC with no 131 iodine ((131)I) uptake.

DESIGN AND METHODS

Forty-eight cancer tissues were divided into three groups: Group 1, 28 primary cancers; Group 2, 7 recurrences capable of trapping (131)I; and Group 3, 13 recurrences incapable of trapping (131)I. mRNA levels of thyroid genes (sodium/iodide symporter NIS, thyroglobulin, thyroperoxidase and pendrin) and glycolytic metabolism genes (GLUT-1, hexokinase I and II) and BRAF mutations were evaluated in the different groups.

RESULTS

Cancers with no (131)I uptake had slightly reduced NIS, significantly reduced thyroglobulin (P < 0.01), thyroperoxidase (P = 0.01) and pendrin (P = 0.03) and significantly increased GLUT-1 (P = 0.01) gene expression levels; and a high frequency of BRAF mutations (77%). BRAF(V600E) mutation, in both primary and metastatic thyroid cancers, is associated with a marked drop in thyroperoxidase (29-fold) and pendrin (20-fold) expression and a considerable increase (five-fold) in GLUT-1 expression.

CONCLUSIONS

(1) The loss of (131)I uptake in recurrences depends not only on a decrease in NIS gene, but possibly on a reduction in the molecules regulating its intracellular metabolism; (2) the high GLUT-1 gene expression supports the use of positron emission tomography with specific tracers in clinical management of such cancers; and (3) BRAF(V600E) point mutations may lead to less differentiated phenotypes, suggesting a worse prognosis.