DNA FISH Diagnostic Assay on Cytological Samples of Thyroid Follicular Neoplasms.

Although fine-needle aspiration cytology (FNAC) is helpful in determining whether thyroid nodules are benign or malignant, this distinction remains a cytological challenge in follicular neoplasms. Identification of genomic alterations in cytological specimens with direct and routine techniques would therefore have great clinical value. A series of 153 cases consisting of 72 and 81 histopathologically confirmed classic follicular adenomas (cFAs) and classic follicular thyroid carcinomas (cFTCs), respectively, was studied by means of different molecular techniques in three different cohorts of patients (pts). In the first cohort (training set) of 66 pts, three specific alterations characterized by array comparative genomic hybridization (aCGH) were exclusively found in half of cFTCs. These structural abnormalities corresponded to losses of 1p36.33-35.1 and 22q13.2-13.31, and gain of whole chromosome X. The second independent cohort (validation set) of 60 pts confirmed these data on touch preparations of frozen follicular neoplasms by triple DNA fluorescent in situ hybridization using selected commercially available probes. The third cohort, consisting of 27 archived cytological samples from an equal number of pts that had been obtained for preoperative FNAC and morphologically classified as and histologically verified to be follicular neoplasms, confirmed our previous findings and showed the feasibility of the DNA FISH (DNA fluorescent in situ hybridization) assay. All together, these data suggest that our triple DNA FISH diagnostic assay may detect 50% of cFTCs with a specificity higher than 98% and be useful as a low-cost adjunct to cytomorphology to help further classify follicular neoplasms on already routinely stained cytological specimens.

Ultrasound criteria of malignancy for cervical lymph nodes in patients followed up for differentiated thyroid cancer.

CONTEXT: Neck ultrasonography (US) has become a keystone in the follow-up of patients with differentiated thyroid cancer. OBJECTIVE: The aim of this study was to determine specificity and sensitivity of ultrasound criteria of malignancy for cervical lymph nodes (LNs) in patients with differentiated thyroid cancer. DESIGN: We prospectively studied 19 patients referred to the Institut Gustave Roussy for neck LN dissection. All patients underwent a neck US within 4 d prior to surgery. Only LNs that were unequivocally matched between US and pathology were taken into account for the analysis. RESULTS: One hundred three LNs were detected on US, 578 LNs were surgically removed, and 56 LNs were analyzed (28 benign and 28 malignant). Sensitivity and specificity were 68 and 75% for the long axis (> or =1 cm), 61 and 96% for the short axis (>5 mm), 46 and 64% for the round shape (long to short axis ratio < 2), 100 and 29% for the loss of fatty hyperechoic hilum, 39 and 18% for hypoechogenicity, 11 and 100% for cystic appearance, 46 and 100% for hyperechoic punctuations, and 86 and 82% for peripheral vascularization. CONCLUSION: Cystic appearance, hyperechoic punctuations, loss of hilum, and peripheral vascularization can be considered as major ultrasound criteria of LN malignancy. LNs with cystic appearance or hyperechoic punctuations are highly suspicious of malignancy. LNs with a hyperechoic hilum should be considered as benign. Peripheral vascularization has the best sensitivity-specificity compromise. Round shape, hypoechogenicity, and the loss of hilum taken as single criteria are not specific enough to suspect malignancy.

Prognostic parameters of metastatic adrenocortical carcinoma.

CONTEXT: Prognostic parameters of metastatic adrenocortical carcinoma (ACC) are poorly characterized. OBJECTIVE: The objective of the study was to describe the clinical presentation of metastatic ACC and determine prognostic factors for survival. DESIGN: This was a retrospective cohort study (1988-2004). SETTING: The study was conducted in an institutional practice. PATIENTS: Participants included 124 consecutive patients with metastatic ACC, 70 from Gustave-Roussy Institute (main cohort) and 54 patients from the Cochin Hospital (validation cohort). Clinical data concerning all patients, histopathologic slides of primary tumors (44 in the main cohort and 40 in the validation cohort), and molecular biology data on 15 primary tumors (main cohort) were analyzed. INTERVENTION: There was no intervention. MAIN OUTCOME: The main outcome was the specific survival after discovery of the first metastasis (Kaplan-Meier method). This included univariate analysis on the main cohort, confirmed on the validation cohort and then analyzed in a multivariate analysis. RESULTS: In the main cohort, overall median survival was 20 months. In univariate analysis, the presence of hepatic and bone metastases, the number of metastatic lesions and the number of tumoral organs at the time of the first metastasis, a high mitotic rate (>20 per 50 high-power field), and atypical mitoses in the primary tumor predicted survival (P = 0.05, 0.003, 0.046, 0.001, 0.01, and < 0.001, respectively). The number of tumoral organs and a high mitotic rate were confirmed on the validation cohort (P = 0.009 and 0.03, respectively). These two parameters were confirmed in multivariate analysis (P = 0.0058 and 0.049). CONCLUSION: Metastatic ACC is a heterogeneous disease with poor outcome. The combination of the number of tumoral organs at the time of the first metastasis and the mitotic rate can predict different outcomes.

Sodium/iodide symporter (NIS) gene expression is the limiting step for the onset of thyroid function in the human fetus.

CONTEXT: Terminal differentiation of the human thyroid is characterized by the onset of follicle formation and thyroid hormone synthesis at 11 gestational weeks (GW). OBJECTIVE: This study aimed to investigate the ontogeny of thyroglobulin (Tg), thyroid peroxidase (TPO), sodium/iodide symporter (NIS), pendrin (PDS), dual oxidase 2 (DUOX2), thyroid-stimulating hormone receptor (TSHR), and thyroid transcription factor 1 (TITF1), forkhead box E1 (FOXE1), and paired box gene 8 (PAX8) in the developing human thyroid. DESIGN: Thyroid tissues from human embryos and fetuses (7-33 GW; n = 45) were analyzed by quantitative PCR to monitor mRNA expression for each gene and by immunohistochemistry to determine the cellular distribution of TITF1, TSHR, Tg, TPO, NIS, and the onset of T4 production. A broken line regression model was fitted for each gene to compare the loglinear increase in expression before and after the onset of T4 synthesis. RESULTS: TITF1, FOXE1, PAX8, TSHR, and DUOX2 were stably expressed from 7 to 33 GW. Tg, TPO, and PDS expression was detectable as early as 7 GW and was correlated with gestational age (all, P < 0.01), and the slope of the regression line was significantly different before and after the onset of T4 synthesis at 11 GW (all, P < 0.01). NIS expression appeared last and showed the highest fit by the broken line regression model of all genes (correlation age P < 0.0001, broken line regression P < 0.0001). Immunohistochemical studies detected TITF1, TSHR, and Tg in unpolarized thyrocytes before follicle formation. T(4) and NIS labeling were only found in developing follicles from 11 GW on. CONCLUSION: These results imply a key role of NIS for the onset of human thyroid function.

Poorly differentiated follicular thyroid carcinoma: prognostic factors and relevance of histological classification.

OBJECTIVE: Poorly differentiated follicular thyroid carcinoma (PDFC) is a tumor of follicular cell origin with attributes intermediate between well-differentiated carcinomas and anaplastic carcinomas, but neither a clear histological description nor an established definition of prognostic indicators are available. DESIGN: This study correlates the clinical outcome and survival of 40 PDFC patients with histological architecture, cytological characteristics, and expression of various markers of cell proliferation and differentiation (cyclin A, cyclin B1, cyclin D1, cyclin E, Ki67, thyroperoxidase, galectin 3, dual oxidase [Duox], vascular endothelial growth factor, epidermal growth factor receptor, and p53). MAIN OUTCOME: At 5 years, the overall survival rate was 63% and the metastasis-free survival rate was 57%. An older age at the time of diagnosis and a larger tumor size were associated with an increased risk of distant metastases and of cancer-related death. Polymorph architecture was associated with a reduced risk of metastases, whereas a high expression of Duox was associated with a reduced risk of death. In these patients with PDFC, no other histological features or expression of any other marker had a prognostic significance. CONCLUSION: PDFC has a more aggressive behavior than well-differentiated carcinomas; prognosis is related to indicators that are also relevant in patients with well-differentiated carcinomas.

Functional characterization of human thyroid tissue with immunohistochemistry.

Immunohistochemistry provides insights in the expression of functional proteins and of their localization in normal thyroid tissue and in thyroid diseases. In hyperfunctional thyroid tissues, staining for sodium/iodide symporter (NIS), pendrin, thyroid peroxidase (TPO), and thyroglobulin (Tg) is increased. In hypofunctioning thyroid tissues, NIS staining is markedly decreased; in benign hypofunctioning adenomas, the expression of the other functional proteins is unmodified or slightly decreased, whereas their expression is profoundly decreased or absent in differentiated thyroid carcinoma.

Medullary thyroid carcinoma arises in the absence of prolactin signaling.

Prolactin, a pituitary hormone, exerts pleiotropic effects in various cells. These effects are mediated by a membrane receptor highly expressed in many tissues. To analyze prolactin effects on the thyroid gland, we first identified prolactin receptor (PRLR) mRNAs by in situ hybridization. To further evaluate the physiologic relevance of PRLR actions in the thyroid in vivo, we used PRLR knockout mice. Whereas the histologic structure of thyroid of PRLR-null mice was not disturbed, we show that T4 levels are lower in null animals (13.63 +/- 2.98 versus 10.78 +/- 2.25 pmol/L in null mice), confirming that prolactin participates in the control of thyroid metabolism. To further investigate thyroid effects in mice, we measured body temperature and thyroid-stimulating hormone in young and adult male and/or female PRLR-null mice and their normal siblings. Surprisingly, in null animals, we saw medullary thyroid carcinoma (MTC) arising from parafollicular C cells producing calcitonin. The incidence of these carcinomas attained 41% in PRLR-null mice, whereas this malignant tumor occurs sporadically or as a component of the familial cancer syndrome in humans. This finding suggests that PRLR-null mice could represent a valuable animal model for MTC, which could be compared with existing MTC models. These observations suggest a possible link between the appearance of this carcinoma and the absence of prolactin signaling.

Ductal metaplasia in chronic lymphocytic thyroiditis as a manifestation of phylogenic regression to an exocrine structure.

From a morphologic and functional point of view the thyroid can be considered as both an exocrine and endocrine organ. Firstly, thyroglobulin is secreted at the apical pole of the thyrocyte. Secondly, after endocytosis thyroglobulin is lysed and T3 and T4 are secreted at the basal pole into the bloodstream. However, usually exocrine glands are constituted of 2 well separate components: an acinus/alveolar component and an exocrine duct component. Under particular conditions such as chronic injury the acinus/alveolar component is rapidly destroyed, whereas the ductal component seems to be far more resistant and can proliferate giving rise to a tubular network described as "ductulus reaction" or "ductal metaplasia." Normal exocrine ducts and metaplastic ducts exhibit common genetic and phenotypic features directly related to their tubular morphology. In this study, we describe in lymphocytic autoimmune thyroiditis the appearance of ductal-like structures which displayed the features of ductal metaplasia.

Prognostic factors for persistent or recurrent disease of papillary thyroid carcinoma with neck lymph node metastases and/or tumor extension beyond the thyroid capsule at initial diagnosis.

CONTEXT: Reliable prognostic factors are needed in papillary thyroid cancer patients to adapt initial therapy and follow-up schemes to the risks of persistent and recurrent disease. OBJECTIVE AND SETTINGS: To evaluate the respective prognostic impact of the extent of lymph node (LN) involvement and tumor extension beyond the thyroid capsule, we studied a group of 148 consecutive papillary thyroid cancer patients with LN metastases and/or extrathyroidal tumor extension. Initial treatment, performed at the Institut Gustave Roussy between 1987 and 1997, included in all patients a total thyroidectomy with central and ipsilateral en bloc neck dissection followed by radioactive iodine ablation. RESULTS: Uptake outside the thyroid bed, demonstrating persistent disease, was found on the postablation total body scan (TBS) in 22% of the patients. With a mean follow-up of 8 yr, eight patients (7%) with a normal postablation TBS experienced a recurrence. Ten-year disease-specific survival rate was 99% (confidence interval, 97-100%). Significant risk factors for persistent disease included the numbers of LN metastases (>10) and LN metastases with extracapsular extension (ECE-LN >3), tumor size (>4 cm), and LN metastases location (central). Significant risk factors for recurrent disease included the numbers of LN metastases (>10), ECE-LN (>3), and thyroglobulin level measured 6-12 months after initial treatment after T4 withdrawal. CONCLUSION: We highlight an excellent survival rate and suggest risk classifications of persistent and recurrent disease based on the numbers of LN metastases and ECE-LN, LN metastases location, tumor size, and thyroglobulin level.

Radiation exposure and familial aggregation of cancers as risk factors for colorectal cancer after radioiodine treatment for thyroid carcinoma.

PURPOSE: In thyroid cancer patients, radioiodine treatment has been shown to be associated with an increased risk of colon carcinoma. The aim of this study in thyroid cancer patients was to evaluate the role of familial factors in the risk of colorectal cancer and their potential interaction with radioiodine exposure. METHODS AND MATERIALS: We performed a case-control study on 15 colorectal cancer patients and 76 matched control subjects, nested in a cohort of 3708 thyroid cancer patients treated between 1933 and 1998. For each patient, the radiation dose delivered to the colon by radioiodine was estimated by use of standard tables. In those who received external radiation therapy, the average radiation doses delivered to the colon and rectum were estimated by use of DOS_Eg software. A complete familial history was obtained by face-to-face interviews, and a familial index was defined to evaluate the degree of familial aggregation. RESULTS: The risk of colorectal cancer increased with familial aggregation of colorectal cancer (p = 0.02). After adjustment for the radiation dose delivered to the colon and rectum, the risk of colorectal cancer was 2.8-fold higher (95% CI, 1.0-8.0) for patients with at least one relative affected by colorectal cancer than for patients without such a family history (p = 0.05). The radiation dose delivered to the colon and rectum by (131)I and external radiation therapy was associated with an increase of risk near the significance threshold (p = 0.1). No significant interaction was found between radiation dose and having an affected relative (p = 0.9). CONCLUSIONS: The role of familial background in the risk of colorectal cancer following a differentiated thyroid carcinoma appears to increase with the radiation dose delivered to the colon and rectum. However, the study population was small and no interaction was found between these two factors.

Iodotyrosine dehalogenase 1 (DEHAL1) is a transmembrane protein involved in the recycling of iodide close to the thyroglobulin iodination site.

In the thyroid, iodotyrosine dehalogenase acts on the mono and diiodotyrosines released during the hydrolysis of thyroglobulin to liberate iodide, which can then reenter the hormone-producing pathways. It has been reported that the deiodination of iodotyrosines occurs predominantly in the microsomes and is mediated by NADPH. Recently, two cDNAs, 7401- and 7513-base pairs long that encode proteins with a conserved nitroreductase domain were published in GenBank as iodotyrosine dehalogenase 1 (DEHAL1) and iodotyrosine dehalogenase 1B (DEHAL1B), respectively. We report here our investigation of the localization and activity of one of these isoforms, DEHAL1. DEHAL1 mRNA is highly expressed in the thyroid, is up-regulated by cAMP, and encodes a transmembrane protein that efficiently catalyzes the NADPH-dependent deiodination of mono (L-MIT) and diiodotyrosine (L-DIT), with greater activity vs. L-MIT. Iodotyrosine deiodinase was active in HEK293 cells transfected by DEHAL1 cDNA, but not in CHO cells. A fraction of DEHAL1 protein is exposed to the cell surface, as indicated by biotinylation experiments. Immunohistochemistry studies showed that DEHAL1 proteins accumulate at the apical pole of thyrocytes. Taken together, these findings indicate that the deiodination reaction occurs at the apical pole of the thyrocyte and is involved in a rapid iodide recycling process at and/or close to the organification site.

Regulation by human chorionic gonadotropin of sodium/iodide symporter gene expression in the JAr human choriocarcinoma cell line.

Sodium/iodide symporter (NIS) gene and protein expressions have been recently described in human cytotrophoblasts, emphasizing its potential function in the active transport of iodide from the mother to the fetus. In this study we analyzed NIS expression and function in the human JAr placental choriocarcinoma cell line. Using real-time quantitative RT-PCR, we first demonstrated that NIS transcripts are expressed at a high level in JAr cells compared with other cell lines, including thyroid cancer cells. Functional analysis clearly showed that Jar cells are able to concentrate iodide in presence of hCG. Iodide accumulation increased after 2-h exposure to 5 IU/ml hCG, to 6-fold over the basal level after 8 h. This effect was reproduced using forskolin, the cAMP analog (Bu)(2)-cAMP, and phorbol acetate. Moreover, hCG increased both NIS mRNA after 2 h and NIS protein levels after 4 h, reaching a maximum after 8 h in both cases. In conclusion, our data demonstrate that 1) NIS is expressed in JAr cells; 2) iodide transport in JAr cells is regulated by hCG and by cAMP-dependent and -independent mechanisms; 3) the stimulation of iodide uptake is due to an increase in both NIS mRNA and protein levels; and 4) JAr cells may represent an excellent in vitro model suitable to analyze the molecular mechanisms involved in iodide transport from mother to fetus.

Rationale for central and bilateral lymph node dissection in sporadic and hereditary medullary thyroid cancer.

UNLABELLED: A retrospective study was performed on 101 consecutive medullary thyroid cancer (MTC) patients who underwent at Institut Gustave-Roussy (IGR) total thyroidectomy with central and bilateral lymph node dissection. At histology, lymph node metastases were found in 55% of patients. In sporadic MTC, lymph node metastases were observed in the central compartment in 50% of patients, in the ipsilateral jugulocarotid chain in 57%, and in the contralateral jugulocarotid chain in 28%. In hereditary MTC, lymph node metastases were identified in the central compartment in 45% of patients, in the ipsilateral jugulocarotid chain in 36%, and in the contralateral jugulocarotid chain in 19%. Contralateral lymph nodes were found in 37% of metastatic patients with an unilateral tumoral involvement of the thyroid gland. A strong association was observed between tumor size and lymph node involvement for both hereditary and sporadic MTC (P < 0.02). Permanent hypoparathyroidism occurred in 4% of patients and laryngeal nerve palsy in 5%. An undetectable calcitonin level was obtained after surgery in 61% of patients, in 95% of patients without lymph node metastases, and in 32% of patients with lymph node metastases. Among patients with lymph node involvement, undetectable calcitonin level was obtained in 57% of patients with less than or with 10 lymph node metastases and in 4% of patients with more than 10 (P < 0.01). IN CONCLUSION: 1) lymph node metastases occur early in the course of MTC; 2) the pattern of lymph node metastatic distribution in neck areas varied between patients and was not related to the thyroid tumor size; 3) contralateral lymph node metastases were observed even in patients with small thyroid tumor; 4) total thyroidectomy with central and complete bilateral neck dissection should be performed routinely in all patients with sporadic and hereditary MTC, even in those with small thyroid tumors-a contralateral neck dissection may be avoided only in sporadic MTC patients with unilateral involvement of the thyroid gland in the absence of central and ipsilateral neck involvement; and 5) the number of lymph node metastases was predictive of biological cure after surgery.

Identification and characterization of a putative human iodide transporter located at the apical membrane of thyrocytes.

Iodide transport by thyrocytes is a two step process involving transporters located either in the basal or in the apical membranes of the cell. The sodium iodide symporter (NIS) is localized in the basolateral membrane facing the bloodstream and mediates iodide accumulation into thyrocytes. Pendrin has been proposed as an apical transporter. In order to identify new iodide transporters, we developed a PCR cloning strategy based on NIS sequence homologies. From a human kidney cDNA library, we characterized a gene, located on chromosome 12q23, that encodes a 610 amino acid protein sharing 46% identity (70% similarity) with the human NIS. Functional analysis of the protein expressed in mammalian cells indicates that it catalyzes a passive iodide transport. The protein product was immunohistochemically localized at the apical pole of the thyroid cells facing the colloid lumen. These results suggest that this new identified protein mediates iodide transport from the thyrocyte into the colloid lumen through the apical membrane. It was designated hAIT for human Apical Iodide Transporter.

Familial medullary thyroid carcinoma: clinical variability and low aggressiveness associated with RET mutation at codon 804.

Sixty-one heterozygotes harboring the germline V804L mutation of the RET protooncogene were identified in five independent families. A total of 31 subjects underwent surgery. Histology identified C cell hyperplasia in 30 cases, isolated in 12 and associated with medullary thyroid carcinoma (MTC) in 18. Six patients with MTC had lymph node metastases. Among the 14 patients with basal detectable calcitonin (CT) level, 12 had MTC and 2 had isolated C cell hyperplasia. In most individuals carrying 804 RET mutation, C cell disease displayed late onset and an indolent course; a pentagastrin test was negative in the majority of heterozygotes during the first 2 decades and was positive in only half of them during the third and fourth decades of life. Interestingly, concomitant somatic M918T was detected in a 12-yr-old girl with MTC and was likely to be responsible for both the early clinical appearance and the aggressiveness of the disease. Our data show that in these gene carriers, surgery may be postponed to the fourth decade of life or until the pentagastrin stimulation test becomes positive. Indeed, our data should be confirmed on a larger series of V804L carriers, but may offer a balanced strategy to keep under control and prevent development of the full disease phenotype.

Expression of the apical iodide transporter in human thyroid tissues: a comparison study with other iodide transporters.

Iodide transport by thyrocytes involves two transporters, namely the Na(+)/I (-) symporter located at the basolateral pole and possibly pendrin in the apical membranes of the cell. Recently, we identified a human gene and its protein product, designated hAIT, as a putative new transporter involved in iodide transfer across the apical membrane of thyrocytes. In the present report, we analyzed both hAIT gene and protein expressions in a large series of benign and malignant human thyroid tissues. Using immunohistochemistry, hAIT staining was detected in normal thyroid tissue in about 10% of follicles; in positive follicles, 10-40% of thyrocytes, mostly the tall cells, were stained. In thyroid tissues obtained from patients with Graves' disease and toxic adenomas, hAIT mRNA and protein levels were similar to those found in normal tissue. In hypofunctioning adenomas, hAIT mRNA levels were slightly decreased, and apical iodide transporter (AIT) immunostaining was similar to that observed in normal thyroid tissue. AIT staining was stronger in Hürthle cell adenomas and in microfollicular adenomas. In thyroid carcinomas, the mean and median hAIT mRNA levels were significantly decreased. Expression of AIT protein was undetectable in most papillary carcinomas and was weak but detectable in most follicular carcinomas; it was negative in anaplastic carcinomas.

Combined treatment of anaplastic thyroid carcinoma with surgery, chemotherapy, and hyperfractionated accelerated external radiotherapy.

PURPOSE: To analyze a prospective protocol combining surgery, chemotherapy (CT), and hyperfractionated accelerated radiotherapy (RT) in anaplastic thyroid carcinoma. METHODS AND MATERIALS: Thirty anaplastic thyroid carcinoma patients (mean age, 59 years) were treated during 1990-2000. Tumor extended beyond the capsule gland in 26 patients, with tracheal extension in 8. Lymph node metastases were present in 18 patients and lung metastases in 6. Surgery was performed before RT-CT in 20 patients and afterwards in 4. Two cycles of doxorubicin (60 mg/m(2)) and cisplatin (120 mg/m(2)) were delivered before RT and four cycles after RT. RT consisted of two daily fractions of 1.25 Gy, 5 days per week to a total dose of 40 Gy to the cervical lymph node areas and the superior mediastinum. RESULTS: Acute toxicity (World Health Organization criteria) was Grade 3 or 4 pharyngoesophagitis in 10 patients; Grade 4 neutropenia in 21, with infection in 13; and Grade 3 or 4 anemia and thrombopenia in 8 and 4, respectively. At the end of the treatment, a complete local response was observed in 19 patients. With a median follow-up of 45 months (range, 12-78 months), 7 patients were alive in complete remission, of whom 6 had initially received a complete tumor resection. Overall survival rate at 3 years was 27% (95% confidence interval 10-44%) and median survival 10 months. In multivariate analysis, tracheal extension and macroscopic complete tumor resection were significant factors in overall survival. Death was related to local progression in 5% of patients, to distant metastases in 68%, and to both in 27%. CONCLUSIONS: Main toxicity was hematologic. High long-term survival was obtained when RT-CT was given after complete surgery. This protocol avoided local tumor progression, and death was mainly caused by distant metastases.

Age-dependent variation of follicular size and expression of iodine transporters in human thyroid tissue.

UNLABELLED: The high sensitivity of the thyroid gland to the carcinogenic effects of radiation during childhood contrasts with the absence of demonstrable carcinogenic effects of radiation in adults. To better understand these age-related variations, we studied follicular morphometry, functional status, and proliferative activity in 31 thyroid glands removed from relatives of medullary thyroid carcinoma patients, with ages ranging from 3 to 39 y. METHODS: The mean follicular diameter (MFD) was estimated, and immunohistochemistry was performed with antibodies directed to molecules involved in iodide transport (Na(+)/I(-) symporter [NIS], pendrin, and apical iodide transporter), in organification (thyroperoxidase [TPO] and Duox), in cell cycle and growth (Ki-67, cyclin A and D1, and galectin-3), and in angiogenesis (vascular endothelial growth factor and nitric oxide synthase III [NOSIII]). RESULTS: Compared with older patients, patients who were < or =12 y old had a smaller MFD (P < 0.001) and more frequently positive NIS, pendrin, and Duox (P < 0.01). Proliferation rate as indicated by cyclin A expression was also higher in patients < 12 y (P < 0.01) but peaked at the time of puberty. Staining for NIS, pendrin, TPO, Duox, and NOSIII was stronger in thyroid glands with a smaller MFD (P < 0.001). On multiple tests adjusted for age and thyroid mass, TPO, Duox, and NOSIII remained significantly correlated to MFD (P < 0.001), whereas staining for NIS and pendrin did not. This finding suggests that NIS and pendrin expression is related mainly to the age of the patient. CONCLUSION: Smaller follicles with a higher expression of proteins involved in iodide metabolism were found in younger children. In cases of radioiodine contamination in children, the result will be a higher radioactive concentration and, hence, higher radiation doses. This event may induce the development of thyroid cancer under conditions of accelerated proliferation, as evidenced at puberty.

PAX8 and peroxisome proliferator-activated receptor gamma 1 gene expression status in benign and malignant thyroid tissues.

OBJECTIVE: Genetic alterations involving the thyroid transcription factor PAX8 and the peroxisome proliferator-activated receptor gamma 1 (PPARgamma1) genes have been described in thyroid neoplasms. We investigated in a series of thyroid samples, including 14 normal, 13 hyperfunctioning tissues, 26 follicular adenomas, 21 follicular and 41 papillary carcinomas, both the frequency of the PAX8-PPARgamma1 rearrangement and the expression of the PAX8 and PPARgamma transcripts. METHODS: Using RT-PCR followed by sequencing PCR products, PAX8-PPARgamma1 translocation was not detected in benign tissues nor in papillary carcinomas and was detected in 4 (19%) of 21 follicular carcinomas and in one (4%) of 26 follicular adenomas. RESULTS: Specific real-time quantitative RT-PCR (Q RT-PCR) methods detected high levels of PPARgamma transcripts in follicular carcinomas presenting the rearrangement. Interestingly, the level of PPARgamma transcripts was significantly decreased in papillary carcinomas in comparison with those found in benign adenomas and follicular carcinomas. Finally, PAX8 gene expression was decreased in both papillary and follicular thyroid carcinomas, and in these tumors to the same extent in the presence or absence of the rearrangement. These alterations in both PPARgamma and PAX8 gene expression may explain the poorly differentiated histotype of follicular carcinomas harboring the translocation. Immunohistochemistry showed that nuclear PPARgamma staining was weak in normal tissues, adenomas, papillary carcinomas and in some follicular carcinomas, and strong in the follicular carcinomas positive for the PAX8-PPARgamma1 translocation, but also in some follicular tumors in which no translocation could be evidenced. CONCLUSION: These observations confirm that the PAX8-PPARgamma1 translocation characterizes a subset of thyroid follicular carcinomas but is not a specific marker of carcinoma and that its frequency is lower than that initially reported. Finally, immunohistochemistry is not a reliable method for the specific detection of the translocation, that can be specifically evidenced by Q RT-PCR.