Outcome and characteristics of patients with malignant pleural effusion from differentiated thyroid carcinoma.

Metastatic differentiated thyroid carcinoma (DTC) is an uncommon cause of malignant pleural effusion (MPE) and the characteristics and clinical course have been rarely described. Herein, we report a retrospective review of the clinical course of 18 patients (15 women and 3 men) with MPE from DTC who underwent treatment at our institution between January 2005 and December 2014. MPE from DTC was diagnosed based on cytology and/or level of thyroglobulin in the pleural fluid. Pathologically, papillary carcinoma was found in 16 patients and follicular carcinoma in 2 patients. Median ages at initial diagnosis of DTC and MPE were 64 years (range, 22-79) and 74 years (range, 39-86), respectively. All patients showed radiologically apparent lung metastases, with MPE developing after 0-212 months (median, 25). In 16 patients (88.9%), other coexistent distant metastases at the time of MPE diagnosis were found in the bone (n = 10), brain (n = 5), and skin (n = 2). All patients were treated conservatively with palliative thoracentesis or chest tube drainage with or without pleurodesis. Recurrent MPE after treatment was seen in 9 patients; discharge to home health care after treatment for MPE was possible for 14 patients. The overall survival after initial diagnosis varied considerably from 14 months to 37 years, but the median survival after appearance of MPE was 10 months (range, 1-28). Systemic therapy for iodine-resistant recurrent thyroid disease may need to be considered as a treatment option for patients with MPE.

Effects of radioiodine treatment for differentiated thyroid cancer on testis function.

OBJECTIVE: To evaluate the effects of radioactive iodine (RAI) treatment for differentiated thyroid cancer (DTC) on testis function. DESIGN: A prospective longitudinal single-centre study was performed. A comprehensive andrological evaluation including hormonal assessment, semen analysis and scrotal ultrasound was undertaken in male patients undergoing RAI treatment for DTC. METHODS: Hormonal assessment of FSH, LH, testosterone (T), sperm concentration and motility and testis volume were determined in 20 patients in basal conditions, 6 and 12 months after RAI. Results were analysed in the whole group of patients and then separately in those who received one single ablative treatment ('Single' group, n = 10) and those who received multiple treatments ('Multiple' group, n = 10). RESULTS: In basal conditions, 3 of 20 (15%) patients had a reduced sperm count and belonged to the 'Multiple' group. After RAI, an increase of FSH (8·8 ± 1·2 UI/l vs 5·2 ± 1·2, P < 0·005) and a decrease in sperm concentration (28·8 ± 7·7 millions/ml vs 54·5 ± 7·1, P < 0·005) and testis volume (15·2 ± 3·1 vs 13·7 ± 0·8 ml, P < 0·005) occurred at 6 months in the whole group. One year after RAI, seven patients had oligozoospermia (five from the 'Multiple' group and two from the 'Single' group). Permanent impairment of one or more testis function parameters was observed in patients who underwent multiple RAI treatments: 50% for sperm count, 40% for FSH levels and testis volume and, respectively, in 20 and 10% of those who received one single RAI treatment. CONCLUSIONS: The single ablative RAI treatment in cancer patients is better tolerated respect multiple RAI treatments regard testis function. Multiple treatments for recurrent or metastatic disease may cause a permanent impairment of one or more parameters related to the reproductive potential of male patients.

Spinal metastases from thyroid cancer: Some prognostic factors.

BACKGROUND: Spinal metastases (SpMs) from thyroid cancers (TC) significantly reduce quality of life by causing pain, neurological deficits in addition to increasing mortality. Moreover, prognosis factors including surgery remain debated. METHODS: Data were stored in a prospective French national multicenter database of patients treated for SpM between January 2014 and 2017. Fifty-one consecutive patients affected by TC with 173 secondary SpM were included. RESULTS: Mean overall survival (OS) time for all patients from the diagnosis of a thyroid SpM event was 9.1 years (SD 8.7 months). The 1-year, 5-year and 10-year survival estimates were 94% (SD 3.3), 83.8.0% (SD 5.2), and 74.5% (SD 9.9). The median period of time between primary thyroid tumor diagnosis and the SpM event was 31.4 months (SD 71.6). In univariate analysis, good ECOG-PS (status 0 and 1) (p < 0.0001), ambulatory status (Frankel score) (p < 0.0001) and no epidural involvement (p = 0.01), were associated with longer survival, whereas cancer subtype (p = 0.436) and spine surgery showed no association (p = 0.937). Cox multivariate proportional hazard model only identified good ECOG-PS: 0 [HR: 0.3, 95% CI 0.1-0.941; p < 0.0001], 1 [HR: 0.8, 95% CI 0.04-2.124; p = 0.001] and ambulatory neurological status: Frankel E [HR: 0.262, 95% CI 0.048-1.443; p = 0.02] to be independent predictors of better survival. CONCLUSION: For cases presenting SpM from TC, we highlighted that the only prognostic factors were the progression of the cancer (ECOG-PS) and the clinical neurological impact of the SpM (Frankel status). Surgery should be discussed mainly for stabilization and neurological decompression.

P-wave dispersion in endogenous and exogenous subclinical hyperthyroidism.

BACKGROUND: The aim of this study was to measure maximum P wave duration (Pmax) and P wave dispersion (PWD), which can be indicators for the risk of paroxysmal atrial fibrillation when increased, and to reveal their relationship with thyroid hormone levels in patients with endogenous and exogenous subclinical hyperthyroidism. METHODS: Seventy-one patients with sublinical thyrotoxicosis (34 endogenous, 37 exogenous) and 69 healthy individuals were enrolled in the study. Pmax and minimum P wave duration (Pmin) on electrocardiogram recordings were measured and PWD was calculated as Pmax-Pmin. RESULTS: Pmax (p<0.001) and PWD (p<0.001) values were significantly higher in patients with endogenous subclinical hyperthyroidism compared with the control group. Pmax (p<0.001) and PWD (p<0.001) values were significantly higher in patients with exogenous subclinical thyrotoxicosis compared with the control group. Pmax (p=0.710) and PWD (p=0.127) were not significantly different in patients with endogenous subclinical hyperthyroidism compared with exogenous subclinical hyperthyroid patients. Pmax and PWD negatively associated with TSH in endogenous and exogenous subclinical hyperthyroidism. CONCLUSION: In the present study, we observed that Pmax and PWD were longer in patients with endogenous and exogenous subclinical hyperthyroidism. Lack of a difference in Pmax and PWD between patients with endogenous and exogenous subclinical hyperthyroidism seems to support the idea that hormone levels rather than the etiology of thyrotoxicosis affect the heart.

Growth inhibition of thyroid follicular cell-derived cancers by the opioid growth factor (OGF) - opioid growth factor receptor (OGFr) axis.

BACKGROUND: Carcinoma of the thyroid gland is an uncommon cancer, but the most frequent malignancy of the endocrine system. Most thyroid cancers are derived from the follicular cell. Follicular carcinoma (FTC) is considered more malignant than papillary thyroid carcinoma (PTC), and anaplastic thyroid cancer (ATC) is one of the most lethal human cancers. Opioid Growth Factor (OGF; chemical term - [Met5]-enkephalin) and its receptor, OGFr, form an inhibitory axis regulating cell proliferation. Both the peptide and receptor have been detected in a wide variety of cancers, and OGF is currently used clinically as a biotherapy for some non-thyroid neoplasias. This study addressed the question of whether the OGF-OGFr axis is present and functional in human thyroid follicular cell - derived cancer. METHODS: Utilizing human ATC (KAT-18), PTC (KTC-1), and FTC (WRO 82-1) cell lines, immunohistochemistry was employed to ascertain the presence and location of OGF and OGFr. The growth characteristics in the presence of OGF or the opioid antagonist naltrexone (NTX), and the specificity of opioid peptides for proliferation of ATC, were established in KAT-18 cells. Dependence on peptide and receptor were investigated using neutralization studies with antibodies and siRNA experiments, respectively. The mechanism of peptide action on DNA synthesis and cell survival was ascertained. The ubiquity of the OGF-OGFr axis in thyroid follicular cell-derived cancer was assessed in KTC-1 (PTC) and WRO 82-1 (FTC) tumor cells. RESULTS: OGF and OGFr were present in KAT-18 cells. Concentrations of 10-6 M OGF inhibited cell replication up to 30%, whereas NTX increased cell growth up to 35% relative to cultures treated with sterile water. OGF treatment reduced cell number by as much as 38% in KAT-18 ATC in a dose-dependent and receptor-mediated manner. OGF antibodies neutralized the inhibitory effects of OGF, and siRNA knockdown of OGFr negated growth inhibition by OGF. Cell survival was not altered by OGF, but DNA synthesis as recorded by BrdU incorporation was depressed by 28% in OGF-treated cultures compared to those exposed to sterile water. The OGF-OGFr axis was detected and functional in PTC (KTC-1) and FTC (WRO 82-1) cell lines. CONCLUSION: These data suggest that OGF and OGFr are present in follicular-derived thyroid cancers, and that OGF serves in a tonically active inhibitory manner to maintain homeostasis of cell proliferation. These results may provide a biotherapeutic strategy in the treatment of these cancers.

Peroxisome proliferator-activated receptor gamma inhibits follicular and anaplastic thyroid carcinoma cells growth by upregulating p21Cip1/WAF1 gene in a Sp1-dependent manner.

Peroxisome proliferator-activated receptor gamma (PPARgamma) has been demonstrated to be anti-neoplastic against various human tumors. The aim of this study was to delineate the molecular mechanism underlying PPARgamma ligand rosiglitazone (BRL) antiproliferative effects in follicular WRO and anaplastic FRO human thyroid carcinoma cells. BRL upregulated the p21Cip1/WAF1 levels in the two thyroid cancer cells, while did not modify the p53 protein content. Different evidences indicate that the p21Cip1/WAF1 upregulation by BRL requires a functional PPARgamma, since it was reversed by silencing PPARgamma and pretreatment with GW9662, an irreversible PPARgamma antagonist. Transient transfection assays showed that BRL triggered the transcriptional activity of p21Cip1/WAF1 promoter gene in a p53-independent way, being a p21Cip1/WAF1 promoter construct deleted in the p53 sites still activated by BRL. The Sp1 inhibitor mithramycin silenced the p21Cip1/WAF1 promoter activity suggesting an important role of Sp1 in mediating BRL activation. The electrophoretic mobility shift and chromatin immunoprecipitation (ChIP) assays evidenced a functional interaction between PPARgamma and Sp1 in regulating p21Cip1/WAF1. Intriguingly, ChIP analysis revealed in the p21Cip1/WAF1 gene promoter an increased recruitment of the RNA Pol II associated with an increased histone H3 acetylation and a reduced H3 methylation. The biological event, consistent with PPARgamma-induced WRO and FRO cell growth inhibition, was reversed by p21Cip1/WAF1 antisense oligonucleotides and was confirmed by increasing the PPARgamma expression, suggesting a crucial role exerted by p21Cip1/WAF1 in PPARgamma action. Our results further candidate BRL as a potential agent able to inhibit tumor progression of follicular and anaplastic thyroid carcinoma.

Core-needle biopsy versus repeat fine-needle aspiration for thyroid nodules initially read as atypia/follicular lesion of undetermined significance.

BACKGROUND: The purpose of this study was to evaluate the role of core-needle biopsy (CNB) by comparing the results of CNB and repeat fine-needle aspiration (FNA) for thyroid nodules that are initially read as atypia/follicular lesion of undetermined significance (AUS/FLUS) on FNA. METHODS: Among 2631 initial AUS/FLUS FNA results, 505 consecutive nodules (295 repeat FNAs and 210 CNBs) were retrospectively analyzed. The primary outcome was inconclusive (ie, nondiagnostic or AUS/FLUS). The secondary outcomes included inconclusive results of the subcategory, risk factors for inconclusive results, and diagnostic performance. RESULTS: CNB demonstrated significantly fewer inconclusive results than repeat FNA for the overall nodules (40.9% vs 63%; p < .001). Repeat FNA and group FLUS were significant risk factors for inconclusive results (odds ratio = 1.92; p =.001 and odds ratio = 2.08; p <.001, respectively). All diagnostic performances using CNB were higher than repeat FNAs. CONCLUSION: CNB is more useful than repeat FNAs for reducing inconclusive results and improving the diagnostic performance of thyroid nodules with initial AUS/FLUS FNA results. © 2016 Wiley Periodicals, Inc. Head Neck 39: 361-369, 2017.

Expression of vascular endothelial growth factor (VEGF) and its receptors in thyroid carcinomas of follicular origin: a potential autocrine loop.

OBJECTIVE: The aim of this study was to clarify the role of vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) pathways in thyroid tumourigenesis. METHODS: We examined VEGF, VEGFR-1 and VEGFR-2 expression on 34 papillary thyroid carcinomas (PTCs), 18 follicular thyroid carcinomas (FTCs), eight poorly differentiated thyroid carcinomas (PDTCs) and on a thyroid tumour-derived cell line (NPA'87) by immunohistochemistry, reverse transcriptase PCR, immunofluorescence and Western blotting. RESULTS: We have demonstrated that VEGF expression was significantly (P < 0.05) more prevalent in PTCs (79%) than in FTCs (50%) or PDTCs (37%). Similarly, 76% of PTCs, 83% of FTCs and 25% of PDTCs expressed VEGFR-1, whereas 68% of PTCs, 56% of FTCs and 37% of PDTCs expressed VEGFR-2. Coexpression of VEGF and its receptors was observed in 50% of PTCs, 39% of FTCs and 12% of PDTCs, raising the possibility that VEGF may signal in an autocrine loop in these neoplasias, as observed previously for other types of cancer. In agreement with the idea that autocrine VEGF signalling plays an important role in thyroid carcinogenesis, the blockade of either VEGF or its receptors with neutralizing antibodies significantly reduced cell viability and increased apoptosis levels of the VEGFR-positive thyroid tumour cell line NPA'87. CONCLUSIONS: Our results highlight a previously undefined VEGF autocrine action in thyroid carcinomas which could play a crucial role in tumour cell survival and could represent a useful therapeutic target for thyroid tumours.

Gene profiling identifies genes specific for well-differentiated epithelial thyroid tumors.

Thyroid nodules are common. It would very helpful if genetic markers that can diagnose malignancy from fine needle aspiration samples were available. Few such markers has been thus identified and none are specific. Large panels of potential markers can be screened by microarray technology. Studies done to date have concentrated on single tumor types and thus provide no help in identifying tumor subtype specific markers. To that end we have studied gene profiles of 5 types of benign and malignant thyroid nodular tissue (multinodular goiter, follicular adenoma, papillary and follicular carcinomas). We have identified 195 genes whose differential expression clustered into clinically relevant groups. Twenty-eight genes were selected for further confirmation using real time quantitative polymerase chain reaction. Despite the differences in the microarray panels used, we confirmed the differential regulation of 12 genes previously reported in thyroid cancer, although we found the expression of several genes to be regulated in other histological tumor subtypes than originally described. We found, PCSK2, TRIB1, RAP1 GA1 to be specifically overexpressed in follicular cancer and S100A4 and GK2 in papillary carcinoma. SERP1, RNASE 2 and STATA5 were suppressed in papillary thyroid cancer. We have thus identified new potential markers specific to malignant thyroid tumors. It is apparent that a range of nodular thyroid tissue using large tumor sample numbers is necessary to establish robust markers for malignancy and to categorize tumors on the basis of small tumor samples.

Thyroid circadian timing: roles in physiology and thyroid malignancies.

The circadian clock represents an anticipatory mechanism, well preserved in evolution. It has a critical impact on most aspects of the physiology of light-sensitive organisms. These rhythmic processes are governed by environmental cues (fluctuations in light intensity and temperature), an internal circadian timing system, and interactions between this timekeeping system and environmental signals. Endocrine body rhythms, including hypothalamic-pituitary-thyroid (HPT) axis rhythms, are tightly regulated by the circadian system. Although the circadian profiles of thyroid-releasing hormone (TRH), thyroid-stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3) in blood have been well described, relatively few studies have analyzed molecular mechanisms governing the circadian regulation of HPT axis function. In this review, we will discuss the latest findings in the area of complex regulation of thyroid gland function by the circadian oscillator. We will also highlight the molecular makeup of the human thyroid oscillator as well as the potential link between thyroid malignant transformation and alterations in the clockwork.

The Impact of Noninvasive Follicular Variant of Papillary Thyroid Carcinoma on Rates of Malignancy for Fine-Needle Aspiration Diagnostic Categories.

BACKGROUND: Increased recognition of the indolent nature of noninvasive follicular variant of papillary thyroid carcinoma (NFVPTC) along with greater insight into the molecular alterations of these tumors has prompted endocrine pathologists to question whether these tumors warrant a diagnosis of carcinoma. However, a change in terminology would affect the rates of malignancy of fine-needle aspiration (FNA) diagnostic categories. Therefore, the aim of this study was to determine the percentage decrease in associated risk of malignancy for each FNA diagnostic category if NFVPTCs were no longer termed carcinomas. METHODS: We evaluated a cohort of 655 FNAs with subsequent resection specimens over a 22-month time period. The diagnoses of the preceding FNAs were recorded according to the Bethesda System for Reporting Thyroid Cytopathology. For cases with more than one preceding FNA, the FNA diagnosis associated with the highest risk of malignancy was identified. Slides for all resection specimens with a diagnosis of FVPTC were reviewed to identify noninvasive tumors. By definition, all of these tumors were encapsulated, partially encapsulated, or well circumscribed and lacked any indication of infiltrative growth, capsular penetration, or lymphovascular invasion. RESULTS: Our cohort of 655 FNAs with subsequent resection specimens included 53 (8.1%) nondiagnostic (ND), 167 (25.5%) benign, 97 (14.8%) atypia/follicular lesion of undetermined significance (AUS/FLUS), 88 (13.4%) suspicious for follicular neoplasm (SFN), 94 (14.4%) suspicious for malignancy (SUS), and 156 (23.8%) malignant cases (POS). Surgical resections demonstrated benign findings in 309 (47.2%) and malignant tumors in 346 (52.8%), including 85 NFVPTCs accounting for 24.6% of malignancies. Our rates of malignancy for ND, benign, AUS/FLUS, SFN, SUS, and POS were 18.9%, 13.2%, 39.2%, 45.5%, 87.2%, and 98.7%, respectively. If NFVPTC were no longer termed carcinoma, these rates would drop to 17.0% (10% decrease), 5.4% (59% decrease), 21.6% (45% decrease), 37.5% (18% decrease), 45.7% (48% decrease), and 93.6% (5% decrease), respectively. CONCLUSION: Our findings demonstrate that if terminology were changed and NFVPTCs were not considered carcinomas, the rates of malignancy for FNA diagnostic categories would be substantially decreased, with the most clinically significant decrease seen in the SUS category, which demonstrated a relative decrease of nearly 50%.

Morbidity and mortality in follicular thyroid cancer.

The natural history and results of treatment have been analyzed in a group of 49 patients with follicular thyroid carcinoma who were followed for an average of 10.7 yr. Striking differences between the course of follicular thyroid carcinoma and the course of papillary carcinoma are evident. Deaths from cancer were double (16% for follicular), age at diagnosis was older, and age at death was younger. All deaths and recurrences happened within 13 yr, in contrast to the continued experience of deaths and recurrences in papillary cancer, even through 40 yr of observation. Adverse outcome correlated with extent of disease at diagnosis and with size of primary tumor, but did not correlate with vessel invasion, extent of capsule invasion, degree of dedifferentiation, extent of primary surgery, or radioactive iodide ablation. These observations are again in striking contrast to experience with papillary cancer. No patient with intrathyroidal disease who was under age 45 at diagnosis and with a primary tumor of less than 2.5 cm died. Our observations suggest that follicular cancer, even if apparently intrathyroidal, carries a high mortality rate in patients over age 45 or in those with tumors larger than 2.5 cm at the time of diagnosis and suggest that we must consider additional therapeutic measures in this group of patients, including larger radioiodine doses for initial therapy, external radiotherapy, and even possibly prophylactic chemotherapy.

Immediate causes of death in thyroid carcinoma: clinicopathological analysis of 161 fatal cases.

Most patients with thyroid carcinoma have a good prognosis. Due to the small number of fatal cases, it has not been clarified what conditions result in death for patients with thyroid carcinoma. To provide appropriate management for advanced thyroid carcinoma patients, we analyzed causes of death in 161 fatal cases. Clinical characteristics and immediate (final) causes of death based on pathological conditions were analyzed in 62 anaplastic carcinomas and 99 fatal differentiated carcinomas. Single fatal conditions could not be specified in 55 patients. In the remaining 106 patients, respiratory insufficiency (43%) was the most common specific fatal condition, followed by circulatory failure (15%), hemorrhage (15%), and airway obstruction (13%). Respiratory insufficiency due to remarkable pulmonary metastasis replacing lung tissue, massive hemorrhage and airway obstruction due to uncontrolled local tumors, and circulatory failure resulting from compression of the vena cava by extensive mediastinal or sternal metastases were found to be the most important immediate causes of death. Based on this knowledge, several palliative procedures may be worth considering to improve survival and quality of life in patients with advanced thyroid carcinoma.

Resveratrol induces apoptosis in thyroid cancer cell lines via a MAPK- and p53-dependent mechanism.

Two papillary thyroid carcinoma (PTC) and two follicular thyroid carcinoma (FTC) cell lines treated with resveratrol (RV), 1-10 microM, showed activation and nuclear translocation of MAPK (extracellular signal-regulated kinase 1/2). Cellular abundance of the oncogene suppressor protein p53, serine phosphorylation of p53, and abundance of c-fos, c-jun, and p21 mRNAs were also increased by RV. Inhibition of the MAPK pathway by either H-ras antisense transfection or PD 98059, an MAPK kinase inhibitor, blocked these RV-induced effects. Addition of pifithrin-alpha, a specific inhibitor of p53, or transfection of p53 antisense oligonucleotides caused decreased RV-induced p53 and p21 expression in PTC and FTC cells. Studies of nucleosome levels estimated by ELISA and of DNA fragmentation showed that RV induced apoptosis in both papillary and follicular thyroid cancer cell lines; these effects were inhibited by pifithrin-alpha and by p53 antisense oligonucleotide transfection. PD 98059 and H-ras antisense transfection also blocked induction of apoptosis by RV. Thus, RV acts via a Ras-MAPK kinase-MAPK signal transduction pathway to increase p53 expression, serine phosphorylation of p53, and p53-dependent apoptosis in PTC and FTC cell lines.

ONYX-015, an E1B gene-defective adenovirus, induces cell death in human anaplastic thyroid carcinoma cell lines.

Being one of the most lethal human neoplasms and refractory to such conventional treatment as chemo- and radiotherapy, anaplastic thyroid carcinoma is a prime target for innovative therapy. p53 gene inactivation is a constant feature of this neoplasia. Therefore, we evaluated a therapeutic approach based on an E1B 55-kDa gene-defective adenovirus (ONYX-015) that replicates only in cells with impaired p53 function and leads to cell death. Here we report that the ONYX-015 virus induces cell death in three human thyroid anaplastic carcinoma cell lines (ARO, FRO, and KAT-4). In addition, we found that the growth of xenograft tumors induced in athymic mice by the injection of ARO cells was drastically reduced by ONYX-015 treatment. The ONYX-015 virus worked synergistically with two antineoplastic drugs (doxorubicin and paclitaxel) in inducing ARO and KAT-4 cell death. These results suggest that ONYX-015 may be a valid tool in the treatment of the human thyroid anaplastic carcinoma.

Risk assessment of thyroid follicular cell tumors.

Thyroid follicular cell tumors arise in rodents from mutations, perturbations of thyroid and pituitary hormone status with increased stimulation of thyroid cell growth by thyroid-stimulating hormone (TSH), or a combination of the two. The only known human thyroid carcinogen is ionizing radiation. It is not known for certain whether chemicals that affect thyroid cell growth lead to human thyroid cancer. The U.S. Environmental Protection Agency applies the following science policy positions: 1) chemically induced rodent thyroid tumors are presumed to be relevant to humans; 2) when interspecies information is lacking, the default is to assume comparable carcinogenic sensitivity in rodents and humans; 3) adverse rodent noncancer thyroid effects due to chemically induced thyroid-pituitary disruption are presumed to be relevant to humans; 4) linear dose-response considerations are applied to thyroid cancer induced by chemical substances that either do not disrupt thyroid functioning or lack mode of action information; 5) nonlinear thyroid cancer dose-response considerations are applied to chemicals that reduce thyroid hormone levels, increase TSH and thyroid cell division, and are judged to lack mutagenic activity; and 6) nonlinear considerations may be applied in thyroid cancer dose-response assessments on a case-by-case basis for chemicals that disrupt thyroid-pituitary functioning and demonstrate some mutagenic activity. Required data for risk assessment purposes is mode of action information on mutagenicity, increases in follicular cell growth (cell size and number) and thyroid gland weight, thyroid-pituitary hormones, site of action, correlations between doses producing thyroid effects and cancer, and reversibility of effects when dosing ceases.

Human thyroid carcinoma cell lines show different retinoic acid receptor repertoires and retinoid responses.

OBJECTIVE: Disturbed expression of retinoic acid (RA) receptors (RAR/RXR) contributes to the pathogenesis and tumor progression of epithelial carcinomas. DESIGN: To examine whether altered responses to retinoids may correlate with differences in RA receptor equipment, retinoid effects were examined in human thyroid carcinoma cell lines of various differentiation stages in culture and after xenotransplantation onto rodent models. METHODS: Cell growth was assessed by the MTT test, mRNA expression was examined by Northern blot and quantitative competitive RT-PCR, and type I 5'-deiodinase (5'DI) activity was measured by in vitro deiodination assay. Nude rats and mice were used for xenotransplantation experiments. RESULTS: All-trans-RA and RAR-selective synthetic retinoids stimulated activity and mRNA expression of the thyroid differentiation marker 5'DI in the follicular thyroid carcinoma cell line FTC-133. In the less differentiated FTC-238 cells, stimulation of 5'DI activity was less pronounced than in FTC-133 cells, and a reduced level of RAR beta mRNA was detected. In the anaplastic thyroid carcinoma cell lines HTh 74 and C 643, the activity of 5'DI was not increased by retinoids, and expression of RAR alpha mRNA was reduced. Proliferation of FTC-133 and FTC-238 cells was decreased by all-trans-RA. Pretreatment of FTC-133 with RA resulted in a reduced tumor growth in xenotransplantation experiments as compared with untreated control cells. This reduction was less pronounced in the case of FTC-238 cells. Thus, retinoid therapy might be applied to treat follicular thyroid carcinomas. However, tumor-specific RAR repertoires need to be analyzed as a prerequisite for successful intervention with appropriate, probably receptor-selective retinoids.

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.