CD73 expression in normal, hyperplastic, and neoplastic thyroid: a systematic evaluation revealing CD73 overexpression as a feature of papillary carcinomas.

CD73 converts AMP to adenosine, an immunosuppressive metabolite that promotes tumorigenesis. This study presents a systematic evaluation of CD73 expression in benign, hyperplastic, and neoplastic thyroid. CD73 expression was assessed by immunohistochemistry in 142 thyroid samples. CD73 was expressed in normal thyroid (3/6) and goiter (5/6), with an apical pattern and mild intensity. Apical and mild CD73 expression was also present in oncocytic cell adenomas/carcinomas (9/10; 5/8) and in follicular adenomas/carcinomas (12/18; 23/27). In contrast, papillary thyroid carcinomas featured extensive and intense CD73 staining (49/50) (vs. normal thyroid/goiter, p < 0.001). Seven of nine anaplastic carcinomas were CD73-positive with heterogeneous extensiveness of staining. Medullary and poorly differentiated carcinomas were mostly CD73-negative (1/6; 2/2). These results were corroborated by NT5E mRNA profiling. Papillary carcinomas feature enhanced CD73 protein and mRNA expression with distinct and intense staining, more pronounced in the invasive fronts of the tumors.

Prevalence of c.2268dup and detection of two novel alterations, c.670_672del and c.1186C>T, in the TPO gene in a cohort of Malaysian-Chinese with thyroid dyshormonogenesis.

OBJECTIVES: The c.2268dup mutation in the thyroid peroxidase (TPO) gene is the most common TPO alteration reported in Taiwanese patients with thyroid dyshormonogenesis. The ancestors of these patients are believed to originate from the southern province of China. Our previous study showed that this mutation leads to reduced abundance of the TPO protein and loss of TPO enzyme activity in a Malaysian-Chinese family with goitrous hypothyroidism. The aim of our study was to provide further data on the incidence of the c.2268dup mutation in a cohort of Malaysian-Chinese and its possible phenotypic effects. SETTING: Cohort study. PARTICIPANTS: Twelve biologically unrelated Malaysian-Chinese patients with congenital hypothyroidism were recruited in this study. All patients showed high thyrotropin and low free thyroxine levels at the time of diagnosis with proven presence of a thyroid gland. PRIMARY OUTCOME MEASURE: Screening of the c.2268dup mutation in the TPO gene in all patients was carried out using a PCR-direct DNA sequencing method. SECONDARY OUTCOME MEASURE: Further screening for mutations in other exonic regions of the TPO gene was carried out if the patient was a carrier of the c.2268dup mutation. RESULTS: The c.2268dup mutation was detected in 4 of the 12 patients. Apart from the c.2268dup and a previously documented mutation (c.2647C>T), two novel TPO alterations, c.670_672del and c.1186C>T, were also detected in our patients. In silico analyses predicted that the novel alterations affect the structure/function of the TPO protein. CONCLUSIONS: The c.2268dup mutation was detected in approximately one-third of the Malaysian-Chinese patients with thyroid dyshormonogenesis. The detection of the novel c.670_672del and c.1186C>T alterations expand the mutation spectrum of TPO associated with thyroid dyshormonogenesis.

Functional analyses of C.2268dup in thyroid peroxidase gene associated with goitrous congenital hypothyroidism.

The c.2268dup mutation in thyroid peroxidase (TPO) gene was reported to be a founder mutation in Taiwanese patients with dyshormonogenetic congenital hypothyroidism (CH). The functional impact of the mutation is not well documented. In this study, homozygous c.2268dup mutation was detected in two Malaysian-Chinese sisters with goitrous CH. Normal and alternatively spliced TPO mRNA transcripts were present in thyroid tissues of the two sisters. The abnormal transcript contained 34 nucleotides originating from intron 12. The c.2268dup is predicted to generate a premature termination codon (PTC) at position 757 (p.Glu757X). Instead of restoring the normal reading frame, the alternatively spliced transcript has led to another stop codon at position 740 (p.Asp739ValfsX740). The two PTCs are located at 116 and 201 nucleotides upstream of the exons 13/14 junction fulfilling the requirement for a nonsense-mediated mRNA decay (NMD). Quantitative RT-PCR revealed an abundance of unidentified transcripts believed to be associated with the NMD. TPO enzyme activity was not detected in both patients, even though a faint TPO band of about 80 kD was present. In conclusion, the c.2268dup mutation leads to the formation of normal and alternatively spliced TPO mRNA transcripts with a consequential loss of TPO enzymatic activity in Malaysian-Chinese patients with goitrous CH.

Variable clinical phenotypes in a family with homozygous c.1159G>A mutation in the thyroid peroxidase gene.

BACKGROUND: Defects in the thyroid peroxidase (TPO) gene have been associated with goitrous congenital hypothyroidism (CH). CASE REPORT: In this study, we report 3 siblings possessing a homozygous mutation, c.1159G>A, but exhibiting different clinical phenotypes in a Malaysian-Malay family. The index patient was diagnosed with CH during a routine neonatal screening but the other 2 siblings appeared to be asymptomatic until the ages of 19 and 12.5, respectively, when they started to develop goiter. RESULTS AND CONCLUSION: The mutation was predicted to interrupt the correct splicing of pre-mRNA and also lead to structural alterations in the functional sites of the mutant TPO. The current results suggest the association of goiter development with a homozygous c.1159G>A mutation, but the CH in the index patient could be triggered by other genetic and epigenetic factors distinct from the c.1159G>A mutation.

A comparative study on the effects of excess iodine and herbs with excess iodine on thyroid oxidative stress in iodine-deficient rats.

This study aimed to compare the effect of excess iodine and herbs with excess iodine on treating iodine deficiency-induced goiter from the perspective of oxidative stress and to measure selenium values in Chinese herbs. One hundred twenty 4-week-old Wistar rats were selected and randomly divided into four groups after inducing iodine-deficiency goiter: normal control group (NC), model control group (MC), iodine excess group (IE), and herbs with iodine excess group (HIE). The activities of oxidative enzymes and levels of oxidative products were measured using biochemical tests. The expression of 4-hydroxynonenal (4-HNE) in the thyroid was detected by immunohistochemistry and the expression of peroxiredoxin 5 (PRDX5) by the Western blot and immunohistochemistry. Selenium values in iodine-excessive herbs were measured by hydride generation-atomic fluorescence spectrometry. The herbs with iodine excess were tested to contain rich selenium. The activities of superoxide dismutase (SOD) and PRDX5 increased markedly, and the values of malondialdehyde (MDA) and 4-HNE decreased significantly in the HIE group. In conclusion, compared with excess iodine, herbs with excess iodine damaged thyroid follicular cells less, which may be related to the increase of antioxidant capacity and rich selenium values in iodine-excessive herbs.

Significance of autotaxin activity and overexpression in comparison to soluble intercellular adhesion molecule in thyroid cancer.

BACKGROUND: The objective of this study was to evaluate the role of autotaxin (ATX) activity and gene expression compared to soluble intercellular adhesion molecule-1 (sICAM-1) in thyroid carcinoma.
 PATIENTS AND METHODS: Sixty-five patients with thyroid swelling were included. There were 20 cases of simple multinodular goiter (group I), 15 cases of follicular adenoma (group II) and 30 cases of thyroid cancer (group III). Group III was further subdivided into negative and positive lymph nodes (group IIIa and IIIb; 22 and 8 cases, respectively). sICAM-1 concentration and ATX activity were measured using colorimetric enzyme-linked immunosorbent assay (ELISA), while ATX gene expression was detected by real-time polymerase chain reaction (PCR).
 RESULTS: sICAM-1 level, ATX activity and gene expression were significantly elevated in patients with thyroid carcinoma compared to other groups. The ATX activity showed significantly higher sensitivity and specificity than sICAM-1 (100% and 97.1% vs 93.3% and 88.6%, respectively). Both sICAM-1 and ATX values were significantly higher in patients with positive lymph nodes compared to those without lymph node involvement (p<0.001). Higher levels of ATX activity and gene expression were significantly correlated with larger tumor size and undifferentiated pathological subtype in thyroid carcinoma. In this respect, ATX was superior to sICAM-1.
 CONCLUSION: Our data suggest that ATX activity and gene expression are reliable diagnostic and prognostic tools in thyroid carcinoma compared to sICAM-1.

Congenital goitrous primary hypothyroidism in two German families caused by novel thyroid peroxidase (TPO) gene mutations.

Congenital hypothyroidism occurs with a prevalence of approximately 1:3 500. Defects in thyroid hormone synthesis which lead to goitrous hypothyroidism account for 10-15% of these cases. Several genetic defects have been characterized and mutations in the thyroid peroxidase (TPO) gene are the most common cause for dyshormonogenesis.So far, more than 80 mutations in the TPO gene have been described, resulting in a variable decrease in TPO bioactivity. Clinically TPO defects manifest with congenital primary goitrous hypothyroidism.We here present 2 children with congenital primary hypothyroidism, who were identified to have compound heterozygous TPO mutations. They both shared the same novel mutation in the TPO gene (C756R) in exon 13. One case presented with an apparently dominant inheritance of thyroid dyshormonogenesis.

Positive correlation between type 1 and 2 iodothyronine deiodinases activities in human goiters.

Type 1 (D1) and 2 (D2) iodothyronine deiodinases are selenocysteine-containing enzymes that catalyze the deiodination of T4 to T3 in the thyroid and in peripheral tissues. Despite their importance to the plasma T3 pool in human beings, there are few studies about their behavior in human thyroids. In order to better understand iodothyronine deiodinase regulation in the thyroid gland, we studied thyroid tissue samples from follicular adenoma (AD, n = 5), toxic diffuse goiter (TDG, n = 6), nontoxic multinodular goiter (NMG, n = 40), papillary thyroid carcinoma (PTC, n = 8), and surrounding normal tissues (NT, n = 7) from 36 patients submitted to elective thyroidectomy. D1 and D2 activities were determined by quantification of the radioiodine released by ¹²5I-rT3 or ¹²5I-T4 under standardized conditions, and expressed as pmol rT3 deiodinated per minute and mg protein (pmol rT3 min⁻¹ mg⁻¹ ptn) and fmol T4 deiodinated per minute and mg protein (fmol T4 min⁻¹ mg⁻¹ ptn), respectively. D1 activity detected in TDG and AD tissues were significantly higher than in NT, PTC or NMG samples. D2 activity was also significantly higher in TDG and AD samples than in PTC, NMG, or NT. There was great variability in D1 and D2 enzymatic activities from distinct patients as well as from different areas from the same goiter. There was a positive correlation (P < 0,0001, r = 0.4942) between D1 and D2 activities when all samples were taken into account, suggesting that-in the thyroid-these two iodothyronine deiodinases may have related regulatory mechanisms, even if conditioned by other as yet unknown factors.

Relaxin enhances the collagenolytic activity and in vitro invasiveness by upregulating matrix metalloproteinases in human thyroid carcinoma cells.

In this study, we identified differential expression of immunoreactive matrix metalloproteinase 2 (MMP2)/gelatinase A, membrane-anchored MT1-MMP/MMP14, and human relaxin-2 (RLN2) in human benign and malignant thyroid tissues. MMP2 and MT1-MMP were detected in the majority of thyroid cancer tissues and colocalized with RLN2-positive cells. MMP2 was mostly absent in goiter tissues and, similar to RLN2, may serve as a marker for thyroid cancer. MMP2 and MT1-MMP were identified as novel RLN2 targets. RLN2 caused a significant downregulation of tissue inhibitor of MMP (TIMP) 3 protein levels but did not change the expression levels of MMP13, and TIMP1, TIMP2, and TIMP4 in human thyroid carcinoma cells. RLN2 failed to affect the expression of MMP1, 3, 8, and 9 in the thyroid carcinoma cells investigated. Stable RLN2 transfectants secreted enhanced levels of bioactive MMP2 which contributed to the increased collagenolytic activity and in vitro invasiveness into collagen matrix by human thyroid cancer cells. Three-dimensional reconstitution of confocal fluorescent microscopy images revealed larger-sized invadopodia, with intense MT1-MMP accumulation at the leading migrating edge in RLN2 transfectants when compared with enhanced green fluorescent protein clones. In RLN2 transfectants actin stress fibers contributed to pseudopodia formation. In conclusion, enhanced tumor cell invasion by RLN2 involves the formation of MT1-MMP-enriched invadopodia that lead to increased collagenolytic cell invasion by human thyroid cancer cells.

Lack of complex I is associated with oncocytic thyroid tumours.

Oncocytic tumours are characterised by hyperproliferation of mitochondria. We immunohistochemically analysed all enzymes of the oxidative phosphorylation system in 19 oncocytic thyroid tumours. A specific lack of complex I was detected, which was expressed at <5% of the level determined in surrounding non-cancerous tissue.

Mutations in the iodotyrosine deiodinase gene and hypothyroidism.

DEHAL1 has been identified as the gene encoding iodotyrosine deiodinase in the thyroid, where it controls the reuse of iodide for thyroid hormone synthesis. We screened patients with hypothyroidism who had features suggestive of an iodotyrosine deiodinase defect for mutations in DEHAL1. Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase. Patients had severe goitrous hypothyroidism, which was evident in infancy and childhood. Two patients had cognitive deficits due to late diagnosis and treatment. Thus, mutations in DEHAL1 led to a deficiency in iodotyrosine deiodinase in these patients. Because infants with DEHAL1 defects may have normal thyroid function at birth, they may be missed by neonatal screening programs for congenital hypothyroidism.

Pseudodominant inheritance of goitrous congenital hypothyroidism caused by TPO mutations: molecular and in silico studies.

CONTEXT AND OBJECTIVE: Most cases of goitrous congenital hypothyroidism (CH) from thyroid dyshormonogenesis 1) follow a recessive mode of inheritance and 2) are due to mutations in the thyroid peroxidase gene (TPO). We report the genetic mechanism underlying the apparently dominant inheritance of goitrous CH in a nonconsanguineous family of French Canadian origin. DESIGN, SETTING, AND PARTICIPANTS: Two brothers identified by newborn TSH screening had severe hypothyroidism and a goiter with increased (99m)Tc uptake. The mother was euthyroid, but the father and two paternal uncles had also been diagnosed with goitrous CH. After having excluded PAX8 gene mutations, we hypothesized that the underlying defect could be TPO mutations. RESULTS: Both compound heterozygous siblings had inherited a mutant TPO allele carried by their mother (c.1496delC; p.Pro499Argfs2X), and from their father, one brother had inherited a missense mutation (c.1978C-->G; p.Gln660Glu) and the other an insertion (c.1955insT; p.Phe653Valfs15X). The thyroid gland of one uncle who is a compound heterozygote for TPO mutations (p.Phe653Valfs15X/p.Gln660Glu) was removed because of concurrent multiple endocrine neoplasia type 2A. Immunohistochemistry revealed normal TPO staining, implying that Gln660Glu TPO is expressed properly. Modeling of this mutant in silico suggests that its three-dimensional structure is conserved, whereas the electrostatic binding energy between the Gln660Glu TPO and its heme group becomes repulsive. CONCLUSION: We report a pedigree presenting with pseudodominant goitrous CH due to segregation of three different TPO mutations. Although goitrous CH generally follows a recessive mode of inheritance, the high frequency of TPO mutations carriers may lead to pseudodominant inheritance.

Pten loss in the mouse thyroid causes goiter and follicular adenomas: insights into thyroid function and Cowden disease pathogenesis.

Inactivation and silencing of the tumor suppressor PTEN are found in many different epithelial tumors, including thyroid neoplasia. Cowden Disease patients, who harbor germ-line PTEN mutations, often display thyroid abnormalities, including multinodular goiter and follicular adenomas, and are at increased risk of thyroid cancer. To gain insights into the role PTEN plays in thyroid function and disease, we have generated a mouse strain, in which Cre-mediated recombination is used to specifically delete Pten in the thyrocytes. We found that Pten mutant mice develop diffuse goiter characterized by extremely enlarged follicles, in the presence of normal thyroid-stimulating hormone and T4 hormone levels. Loss of Pten resulted in a significant increase in the thyrocyte proliferative index, which was more prominent in the female mice, and in increased cell density in the female thyroid glands. Surprisingly, goitrogen treatment did not cause a substantial increase of the mutant thyroid size and increased only to some extent the proliferation index of the female thyrocytes, suggesting that a relevant part of the thyroid-stimulating hormone-induced proliferation signals are funneled through the phosphatidylinositol-3-kinase (PI3K)/Akt cascade. Although complete loss of Pten was not sufficient to cause invasive tumors, over two thirds of the mutant females developed follicular adenomas by 10 months of age, showing that loss of Pten renders the thyroid highly susceptible to neoplastic transformation through mechanisms that include increased thyrocyte proliferation. Our findings show that constitutive activation of the PI3K/Akt cascade is sufficient to stimulate continuous autonomous growth and provide novel clues to the pathogenesis of Cowden Disease and sporadic nontoxic goiter.

CNS hypomyelination in Rat Terrier dogs with congenital goiter and a mutation in the thyroid peroxidase gene.

Arrested physical development and neurologic abnormalities were identified in 3 of 5 Rat Terrier puppies at 9 weeks of age. Bilaterally firm symmetrical masses were palpated in the region of the thyroid glands. Low serum total (T4) and free thyroxine (FT4, by equilibrium dialysis) and markedly elevated thyroid stimulating hormone (TSH) concentrations supported the diagnosis of hypothyroidism. At necropsy, the thyroid gland was grossly enlarged and histologically exhibited severe, diffuse hyperplasia of the follicular epithelium. Gross examination of the central nervous system revealed a myelin deficiency, most evident in the corpus callosum. Regional distribution of hypomyelination was confirmed histologically, affecting the corpus callosum and, to a lesser degree, the corona radiata, the longitudinal fibers of the pons, the pyramids, and the lateral funiculi of the spinal cord. Myelin reduction was paralleled by axon reduction, suggesting that hypomyelination was a consequence of reduced axonal formation. A homozygous nonsense mutation in the thyroid peroxidase gene was identified in the affected puppies. The dam and a clinically normal litter mate were heterozygous for this mutation, confirming simple autosomal recessive inheritance of the disease trait. The same mutation, causing congenital hypothyroidism with a goiter was previously described in the Toy Fox Terrier breed. Given the ongoing practice of introducing the Toy Fox Terrier genetic background into some Rat Terrier breeding programs to obtain a smaller stature and the apparent relative incidence of the disorder in the 2 breeds, it is likely that this mutation crossed into the Rat Terrier breed from Toy Fox Terriers fairly recently.

Inhibition of thyroid peroxidase by Myrcia uniflora flavonoids.

Thyroid peroxidase (TPO), the key enzyme in thyroid hormone biosynthesis, is inhibited by dietary flavonoids; thus, a high consumption of plants containing inhibitory flavonoids may affect thyroid function and lead to hypothyroidism. In this work, TPO inhibition by the aqueous partition of Myrcia uniflora and its isolated compounds has been evaluated. The aqueous partition of the methanolic extract of M. uniflora is able to inhibit TPO activity in vitro. Two known flavonoids were isolated and characterized by mass spectrometry and (1)H NMR from plant extracts: mearnsitrin and myricitrin. The degree of TPO inhibition produced by the aqueous solution of the flavonoids was very high, with a 50% inhibition of the original TPO activity (IC(50)) obtained at 1.97 microM mearnsitrin and at 2.88 microM myricitrin. These results suggest that the indiscriminated consumption of M. uniflora pharmaceutical products allied to the nutritional deficiency of iodine might contribute to the development of hypothyroidism and goiter.

Studies on the goitrogenic mechanism of action of N,N,N',N'-tetramethylthiourea.

N,N,N',N'-Tetramethylthiourea (TMTU) is a rat goitrogen inducing thyroid hyperplasia, hypertrophy, and tumor formation. Little is known about the exact underlying mechanism of action. As thyroid peroxidase (TPO) and type I iodothyronine deiodinase (ID-I) have been established as targets of goitrogenic thiourea derivatives, we investigated interactions of TMTU with target enzymes using a partially purified fraction from hog thyroids or solubilized hog thyroid microsomes and 10,000g supernatant from rat liver homogenate, respectively, as enzyme sources. For comparison, comprehensively characterized goitrogenic thiourea derivatives were studied as well. In contrast to propylthiouracil (PTU), and like ethylenethiourea (ETU), TMTU only marginally affected TPO-catalyzed oxidation of guaiacol. TMTU, like ETU, concentration-dependently suppressed TPO-catalyzed iodine formation with concomitant oxidative metabolism. Suppression ceased upon consumption of thiourea derivatives, the rate of the reappearing iodine formation was similar to that of controls. TMTU, like ETU, also suppressed non-enzymatic and TPO-catalyzed monoiodination of l-tyrosine with a stoichiometry of 2:1, i.e., one molecule of thiourea derivative suppressed two times monoiodination. TMTU and ETU were unable to irreversibly inhibit TPO. In contrast to PTU, TMTU did not inhibit ID-I. These findings provide evidence that TMTU interferes with thyroid hormone synthesis at the level of iodination and demonstrate a metabolic route for the oxidative detoxification of TMTU in the thyroid suggesting that low-level or intermittent exposure to TMTU would have only minimal effects on thyroid hormone synthesis. Finally, it can be concluded that meaningful toxicological studies on TPO inhibition can be performed without a need for highly purified TPO.

Telomerase activity in "suspicious" thyroid cytology.

BACKGROUND: Telomerase activity (TA) has been detected in most malignant neoplasms, including thyroid carcinomas. The authors studied the utility of TA detection as an ancillary tool to thyroid fine-needle aspiration (FNA) for patients with nonconclusive cytologic diagnoses. METHODS: Material obtained by FNA from palpable thyroid nodules in 167 consecutive patients was processed for conventional cytologic studies and simultaneously for TA study. Another 8 patients were excluded from TA because of the presence of lymphocytes. All patients with negative results cases were followed for > 1 year, and those who had tumors that were suspicious or positive by FNA or TA underwent resection for pathologic study of nodules. TA was analyzed by telomere repeat amplification protocol-polymerase chain reaction analysis. RESULTS: After excluding 20 patients because of insufficient material for cytologic study, 120 patients had negative results for malignant cells in cytology material, and the remaining 27 patients had results that were either suspicious (n = 21 patients) or positive (n = 6 patients). Histopathologic confirmation was obtained in 23 patients, including 18 with suspicious cytology (1 with scanty material) and 5 with positive FNA. The histopathologic diagnoses were nodular hyperplasia in 5 patients, follicular adenoma in 3 patients, papillary carcinoma in 11 patients, follicular carcinoma in 1 patient, medullary carcinoma in 2 patients, and lymphoma in 1 patient. TA was detected in 6 of 18 histologically confirmed thyroid neoplasms (1 of 3 follicular adenomas, 3 of 11 papillary carcinomas, 0 of 1 follicular carcinoma, 1 of 2 medullary carcinomas, and 1 of 1 lymphoma), including 1 neoplasm with scanty atypical cells. CONCLUSIONS: The detection of TA helped to confirm neoplasia in 6 of 23 suspicious thyroid nodules. Although it was less sensitive than FNA, TA specificity was 100% for neoplasia and 87.5% for malignancy. The sensitivity of thyroid FNA increased with the use of TA detection when cytology was nonconclusive for malignancy.

Five novel inactivating mutations in the thyroid peroxidase gene responsible for congenital goiter and iodide organification defect.

Thyroid peroxidase (TPO) defects, typically transmitted as autosomal recessive traits, result in hypothyroid goiters with failure to convert iodide into organic iodine. We analyzed the TPO gene in 14 unrelated patients with clinical evidence of iodide organification defects. Seven of the affected individuals harbored mutations in the TPO gene; one was compound heterozygous, the others were simply heterozygous for TPO mutations. Five novel mutations have been identified, one of which was found to be a single nucleotide deletion, while the other four were single nucleotide substitutions. A frameshift mutation c.387delC was detected in exon 5 which leads to an early termination signal in exon 7 (p.N129fsX208). Two missense mutations were identified in exon 8. The first, a c.920A>C transversion that results in a p.N307T substitution, was found in two patients. The second, a c.1297G>A transition, results in p.V433M. A c.1496C>T transition was detected in exon 9 that caused the substitution p.P499L. Finally, in exon 14 a c.2422T>C transition was identified, causing a p.C808R change. In addition, the previously reported GGCC duplication in exon 8 (c.1186_1187insGGCC; p.R396fsX472) was also detected in two affected individuals, one of whom was a compound heterozygous (p.R396fsX472/p.V433M).

Expression of telomerase genes in thyroid carcinoma.

Telomerase (T) is a ribonucleoprotein complex that includes the telomerase RNA component (hTR), telomerase associated protein (TP1) and the telomerase catalytic subunit (hTERT). Telomerase has been shown in stem cells and found to be activated in tumor tissues and immortalized cells. We wanted to test whether the expression of the telomerase complex subunits correlate with the enzyme activity in human thyroid tissue. Hence, we determined the expression of hTERT, hTR and TP1 mRNA by RT-PCR and compared the results to telomerase activity as detected by the telomeric repeat amplification protocol (TRAP) assay. Fifteen benign goiters (G), 11 follicular carcinomas (FTC) including 2 oncocytic follicular carcinomas (also called Hurthle cell carcinoma, oFTC), 12 papillary carcinomas (PTC) including 3 microcarcinomas (mPTC), and 12 undifferentiated anaplastic thyroid carcinomas (UTC) were investigated. Experienced pathologists performed histological and pTNM classification in each specimen. RT-PCR analysis revealed that TP1 was ubiquitously expressed in all G and carcinomas. hTR was expressed in 4 out of 15 G, in 2 out of 3 mPTC, in 5 out of 9 PTC, in 5 out of 9 FTC, in all oFTC and in 9 out of 12 UTC samples. Regarding all carcinomas, no statistically significant correlation was observed between hTR-expression and tumor stage, lymph node or distant metastasis. hTERT-expression was associated with malignancy and tumor stage. All mPTC and 13 out of 15 G did not express hTERT, whereas all samples of pT3-4 tumor stage of FTC, PTC, UTC and all oFTC were positive for hTERT. No telomerase activity could be detected in G. Telomerase activity in carcinoma was only measurable in tissues that expressed the catalytic subunit hTERT. Our data indicate that telomerase activity is up-regulated in neoplastic cells. In contrast to TP1 and hTR, hTERT and telomerase activity may be of help in identifying invasive tumors and may be additional markers for classification of benign goiter and malignant thyroid carcinoma.

Anti-goitrous effect of lecithin-bound iodine in propylthiouracil treated rats.

OBJECTIVE: Excess iodine and some iodine-containing compounds are known to affect various parameters of thyroid function. Lecithin-bound iodine (LBI) is a compound which induces involution of an enlarged thyroid. LBI was tested for its ability to affect thyroid ornithine decarboxylase (ODC) activity and apoptosis. METHODS: LBI was given orally to propylthiouracil-pretreated rats and the changes in ODC activity and apoptosis were observed. The thyroid apoptosis was detected by DNA laddering and flow cytometry. RESULTS: LBI suppressed the thyroid ODC activity within one hour after its administration and lowered slightly but significantly the thyroid putrescine levels at 3 h. The DNA cleavage ladder was evident at 3-6 h after LBI treatment. Propylthiouracil induced thyroid enlargement was reduced significantly at 3 days after chronic treatment with LBI. The thyroidal content of putrescine was also decreased after chronic treatment. These effects of LBI were essentially the same as those of excess iodide, while other iodinated compounds including amiodarone, iopanoic acid and erythrosine had no effect on the thyroid ODC activity. CONCLUSIONS: These results suggest that LBI may exert its anti-goitrous effects, consisting of the inhibition of ODC activity and apoptosis, in the form of inorganic iodide in vivo.