Identifying differentially expressed genes associated with metastasis of follicular thyroid cancer by cDNA expression array.

Patients with follicular thyroid carcinoma have a higher incidence of metastasis than papillary thyroid carcinoma when thyroid cancer is diagnosed. The cDNA expression array technology is utilized herein to profile differentially expressed genes from metastatic human follicular thyroid carcinoma and reveal new tumor markers as well as target genes for therapeutic intervention. Tissue samples were obtained during surgical resection of the thyroid follicular carcinoma and metastatic tissue in the brain of the same patient. Two identical Atlas human cDNA expression arrays were hybridized with 32P-labeled cDNA probes derived from RNA of either primary thyroid cancer or metastatic tissue. Parallel analysis of the hybridized signals allowed us to identify the alteration of gene expression in the metastasis process. Eighteen genes significantly overexpressed and 40 genes significantly underexpressed were identified in the metastatic thyroid cancer. Genes that displayed an altered expression were associated with the processes of cell cycle regulation, apoptosis, DNA damage response, angiogenesis, cell adhesion and mobility, invasion, and immune response. An expression profile of genes that are associated with metastasis process of follicular thyroid cancer was also discussed. Further investigation is required to understand the precise relationship between the altered expression of these genes and the metastasis process of follicular thyroid cancer.     

Id1 gene expression is up-regulated in hyperplastic and neoplastic thyroid tissue and regulates growth and differentiation in thyroid cancer cells

The Id (inhibitor of DNA binding) proteins are a family of helix-loop-helix (HLH) proteins (Id1, Id2, Id3, and Id4) that lack the basic domain necessary for DNA binding. The Id1 protein enhances cell proliferation and inhibits cellular differentiation in a variety of cell types. We have previously demonstrated that the Id1 gene is up-regulated in papillary and medullary thyroid cancers. In this study we characterized the expression and distribution of the Id1 protein in normal, hyperplastic, and neoplastic human thyroid tissue. We also evaluated the effect of the Id1 gene on thyroid cancer cell growth and markers of thyroid cell differentiation. We used semiquantitative immunohistochemistry to characterize Id1 protein expression in normal, hyperplastic (multinodular goiter and Graves' disease), and neoplastic thyroid tissue from 103 patients. Normal thyroid tissue had the lowest level of Id1 protein expression (P < 0.0001). Anaplastic thyroid cancer had the highest level (vs. benign and malignant thyroid tissues, P < 0.01). Id1 protein expression was higher in malignant thyroid tissue than in hyperplastic thyroid tissue (P < 0.02). We found no significant association between the level of Id1 protein expression and patient age, sex, tumor-node-metastasis stage, tumor size, primary tumor vs. lymph node metastasis, primary tumor vs. recurrent tumors, and extent of tumor differentiation. Inhibiting Id1 mRNA expression in thyroid cancer cell lines using Id1 antisense oligonucleotides resulted in growth inhibition (P < 0.03) and decreased thyroglobulin and sodium-iodine symporter mRNA expression (P < 0.02). In conclusion, Id1 is overexpressed in hyperplastic and neoplastic thyroid tissue and directly regulates the growth of thyroid cancer cells of follicular cell origin, but is not a marker of aggressive phenotype in differentiated thyroid cancer.     

All-trans-retinoic acid treatment inhibits the growth of retinoic acid receptor beta messenger ribonucleic acid expressing thyroid cancer cell lines but does not reinduce the expression of thyroid-specific genes

Conventional chemotherapy and radiotherapy are ineffective for the treatment of advanced thyroid tumors like poorly differentiated papillary, anaplastic, and medullary thyroid cancer. In the attempt to evaluate the possibility of using retinoic acid (RA) in the treatment of thyroid cancer refractory to conventional therapy, we studied the effect of all-trans-RA treatment on five human thyroid cancer cell lines. We found that WRO and NPA, derived from follicular and poorly differentiated human thyroid carcinoma, respectively, showed a growth inhibition after 25 and 21 d of RA treatment. Both apoptosis and a decrease in DNA synthesis were observed as mechanisms of growth inhibition. In the NPA cell line, a delay of cell-cycle progression has also been observed. On the contrary, we did not observe any recovery of mRNA expression of thyroid-specific genes and in particular of the sodium iodide symporter gene. The lack of recovery of radioiodide uptake after all-trans-RA treatment confirmed the inability to reexpress sodium iodide symporter mRNA. The main difference between the all-trans-RA responding cells (WRO and NPA) and the nonresponding cells [ARO, FRO (derived from human anaplastic thyroid tumors) and TT (derived from human medullary thyroid tumor)] was the basal and all-trans-RA induced RA receptor (RAR)beta mRNA expression. Interestingly, 14 thyroid tumors (10 papillary and four anaplastic) showed a significant lower expression of RARbeta mRNA when compared with normal thyroid tissues. In agreement with this result, only 30% of papillary thyroid carcinomas analyzed were positive for RARbeta protein expression with a degree of expression that was much lower than that found in normal thyroid tissue. In conclusion we found that all-trans-RA treatment can determine a significant in vitro growth inhibition especially in differentiated thyroid tumor-derived cell lines but it seems unable to reinduce the expression of thyroid-specific genes and in particular to reinduce the ability to take up iodine. The growth inhibition is likely due to apoptosis in an early phase and to a decrease of DNA synthesis later. In some cases, a delay of the cell-cycle progression also may be responsible for the growth inhibition. The finding of a basal and RA-induced RARbeta mRNA expression only in cell lines responding to all-trans-RA suggests that the growth inhibition might be mediated by RARbeta.     

Regulation of tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by DJ-1 in thyroid cancer cells

DJ-1, a cancer-associated protein protects cells from multiple toxic stresses. The expression of DJ-1 and its influence on thyroid cancer cell death has not been investigated so far. We analyzed DJ-1 expression in human thyroid carcinoma cell lines and the effect of DJ-1 on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. DJ-1 was expressed in human thyroid carcinoma cell lines; small interfering RNA-mediated downregulation of its levels significantly sensitized thyroid carcinoma cells to TRAIL-induced apoptosis, whereas the forced exogenous expression of DJ-1 significantly suppressed cell death induced by TRAIL. We also report here that TRAIL-induced thyroid cancer cell apoptosis is mediated by oxidative stress and that DJ-1, a potent nutritional antioxidant, protects cancer cells from apoptosis at least in part by impeding the elevation of reactive oxygen species levels induced by TRAIL and impairing caspase-8 activation. Subsequently, we investigated DJ-1 expression in 52 normal and 74 primary thyroid carcinomas from patients of China Medical University. The protein was not detectable in the 52 specimens of normal thyroid, while 70 out of 74 analyzed carcinomas (33 out of 33 follicular, 17 out of 19 papillary, 12 out of 13 medullar, and 8 out of 9 anaplastic) were clearly positive for DJ-1 expression. Our data demonstrated that DJ-1 is specifically expressed in thyroid carcinomas and not in the normal thyroid tissue. In addition, the protein modulates the response to TRAIL-mediated apoptosis in human neoplastic thyroid cells, at least partially through its antioxidant property.     

The heat shock protein 90-binding geldanamycin inhibits cancer cell proliferation,down-regulates oncoproteins,and inhibits epidermal growth factor-induced invasion in thyroid cancer cell lines

Heat shock protein 90 (HSP90) serves as a chaperone protein and plays a critical role in tumor cell growth and/or survival. Geldanamycin, a specific inhibitor of HSP90, is cytotoxic to several human cancer cell lines, but its effect in thyroid cancer is unknown. We, therefore, investigated the effect of geldanamycin on cell proliferation, oncoprotein expression, and invasion in human thyroid cancer cell lines. We used six thyroid cancer cell lines: TPC-1 (papillary), FTC-133, FTC-236, FTC-238 (follicular), XTC-1 (Hürthle cell), and ARO (anaplastic). We used the dimethyl-thiazol-diphenyltetrazolium bromide assay, a clonogenic assay, an apoptotic assay, and a Matrigel invasion assay. We evaluated oncoprotein expression using Western blots and flow cytometry. After 6 d of treatment with 50 nM geldanamycin, the percent inhibition of growth was 29.4% in TPC-1, 97.5% in FTC-133, 96.7% in FTC-236, 10.8% in FTC-238, 70.9% in XTC-1, and 45.5% in ARO cell lines. In the FTC-133 cell line, geldanamycin treatment decreased clonogenicity by 21% at a concentration of 50 nM; geldanamycin induced apoptosis and down-regulated c-Raf-1, mutant p53, and epidermal growth factor (EGF) receptor expression; geldanamycin inhibited EGF-stimulated invasion. In conclusion, geldanamycin inhibited cancer cell proliferation, down-regulated oncoproteins, and inhibited EGF-induced invasion in thyroid cancer cell lines.     

Fibroblast growth factor receptors as molecular targets in thyroid carcinoma

Several molecular abnormalities of potential therapeutic target value have been described in thyroid neoplastic transition. We report the expression of the fibroblast growth factor receptor family (FGFR-1-4) in normal thyroid tissues, human thyroid cancers of various types and behaviors, and cell lines representative of the spectrum of differentiation of tumors derived from follicular epithelial cells. FGFR-2 was the only receptor consistently detected in normal human thyroid tissue, and its expression diminished in all thyroid cancers and carcinoma cell lines, suggesting that it may have a protective role. FGFR-1 and FGFR-3 were expressed in most well-differentiated tumor types. FGFR-4, however, was expressed predominantly in aggressive tumor types and the most rapidly proliferative cell lines, indicating that it may promote the progression of these tumors. To specifically determine the function of FGFR-4 in thyroid carcinoma, gain- or loss-of-function studies were performed in cell lines representative of the spectrum of thyroid cancer behavior. Introduction of FGFR-4 resulted in enhanced cell proliferation, an effect that was more pronounced in cell lines derived from aggressive tumors than in those derived from more indolent neoplasms. Moreover, transduction of a dominant-negative FGFR attenuated cell proliferation in the aggressive poorly differentiated cell lines with no appreciable effect in well-differentiated cells. Pharmacologic FGFR-4 tyrosine kinase inhibition resulted in significant proliferation arrest in an aggressive cell line endogenously expressing the receptor. Furthermore, systemic administration of the FGFR tyrosine kinase inhibitor PD173074 resulted in significant inhibition of follicular thyroid carcinoma-derived cell growth in xenografted severe combined immunodeficient mice. These data indicate a role for FGFR-4 in human thyroid cancer cell progression and provide a rationale for FGFR manipulation as a potentially novel therapeutic approach.     

Aberrant localization of beta-catenin correlates with overexpression of its target gene in human papillary thyroid cancer

Alterations of the Wnt/beta-catenin signaling pathway are known to occur in mutations of the component genes such as APC, Axin, and beta-catenin, and play a pathogenetic role in tumorigenesis. Activated Wnt signaling stabilizes beta-catenin, which associates with T cell factor, resulting in transactivation of the downstream target genes including c-myc and cyclin D1. To investigate the involvement of Wnt/beta-catenin signaling pathway in thyroid tumorigenesis, we analyzed its activation and localization in 5 human thyroid cancer cell lines and 132 thyroid tumor tissue samples. Dislocalization of beta-catenin was observed in all cell lines. Constitutive activation of T cell factor in two of four thyroid cancer cell lines was observed using reporter gene assay. Furthermore, high expression levels of c-Myc and cyclin D1 were observed in cell lines that showed cytoplasmic or nuclear accumulation of beta-catenin. In 132 paraffin-embedded thyroid carcinoma tissue samples, cytoplasmic beta-catenin was immunohistochemically observed in 52 out of 78 (67%) papillary thyroid cancers, but only in 3 of 34 (9%) follicular adenomas and 5 of 20 (25%) follicular cancers. Cytoplasmic localization of beta-catenin significantly correlated with overexpression of cyclin D1 in papillary carcinomas. Our results suggest that aberrant activation of Wnt/beta-catenin signaling is strongly involved in thyroid tumorigenesis.     

The expression of translocator protein in human thyroid cancer and its role in the response of thyroid cancer cells to oxidative stress

The translocator protein (TSPO), formerly known as a peripheral benzodiazepine receptor, exerts pro-apoptotic function via regulation of mitochondrial membrane potential. We examined TSPO expression in human thyroid tumors (25 follicular adenomas (FA), 15 follicular cancers (FC), and 70 papillary cancers (PC)). The role of TSPO in the regulation of cell growth, migration, and apoptosis was examined in thyroid cancer cell lines after TSPO knockdown with siRNA and after treatment with TSPO antagonist (PK11195). Compared with normal thyroid, the level of TSPO expression was increased in FA, FC, and PC in 24, 26.6, and 55.7% of cases respectively. Thyroid cancer cell lines demonstrated variable levels of TSPO expression, without specific association with thyroid oncogene mutations. Treatment with inhibitors of PI3K/AKT or MEK/ERK signaling was not associated with changes in TSPO expression. Treatment with histone deacetylase inhibitor (valproic acid) increased TSPO expression in TSPO-deficient cell lines (FTC236 cells). TSPO gene silencing or treatment with PK11195 did not affect thyroid cancer cell growth and migration but prevented depolarization of mitochondrial membranes induced by oxidative stress. Induction of TSPO expression by valproic acid was associated with increased sensitivity of FTC236 to oxidative stress-inducible apoptosis. Overall, we showed that TSPO expression is frequently increased in PC. In vitro data suggested the role of epigenetic mechanism(s) in the regulation of TSPO in thyroid cells. Implication of TSPO in the thyroid cancer cell response to oxidative stress suggested its potential role in the regulation of thyroid cancer cell response to treatment with radioiodine and warrants further investigation.     

Thyroid cancer: a lethal endocrine neoplasm

This conference focuses on the controversies about managing thyroid cancer, emphasizing the possibility that the treatment of patients with potentially fatal thyroid cancer may be improved. Although the mortality rate from thyroid cancer is low, it is the highest among cancers affecting the endocrine glands (excluding the ovary). Exposure to radiation during childhood in the 1930s and 1940s increased the incidence of but not the mortality from thyroid cancer, because these tumors are mainly papillary cancers developing in young adults. These rates may change as the exposed cohort ages. Risk factors that increase mortality include older patient age and the growth characteristics of the tumor at diagnosis, the presence of distant metastases, and cell type (for example, the tall-cell variants of papillary cancer, follicular cancer [to be distinguished from the more benign follicular variant of papillary cancer], medullary cancer, and anaplastic cancer). Local metastases in lymph nodes do not seem to increase the risk for death from papillary cancer, but they do increase the risk for death from follicular and medullary cancer. In the latter, mortality is decreased by the early detection and treatment of patients with the familial multiple endocrine neoplasia syndrome 2a. There are excellent tumor markers for differentiated cancer of the parafollicular and of the follicular cells (serum calcitonin and serum thyroglobulin levels, respectively). Measuring the calcitonin level allows early diagnosis of familial medullary cancer, whereas measuring the thyroglobulin level, although useful only after total thyroidectomy, allows early recognition of recurrence or metastases of papillary or follicular cancer. Initial surgery, protocols for follow-up, and the use of radioiodine for the ablation of any residual thyroid and the treatment of metastatic cancer are discussed. Because these tumors resist currently available chemotherapy regimens, possible ways to increase the effectiveness of radioiodine therapy are considered as are new approaches to treatment.     

Transforming acidic coiled-coil 3 and Aurora-A interact in human thyrocytes and their expression is deregulated in thyroid cancer tissues

Aurora-A kinase has recently been shown to be deregulated in thyroid cancer cells and tissues. Among the Aurora-A substrates identified, transforming acidic coiled-coil (TACC3), a member of the TACC family, plays an important role in cell cycle progression and alterations of its expression occur in different cancer tissues. In this study, we demonstrated the expression of the TACC3 gene in normal human thyroid cells (HTU5), and its modulation at both mRNA and protein levels during cell cycle. Its expression was found, with respect to HTU5 cells, unchanged in cells derived from a benign thyroid follicular tumor (HTU42), and significantly reduced in cell lines derived from follicular (FTC-133), papillary (B-CPAP), and anaplastic thyroid carcinomas (CAL-62 and 8305C). Moreover, in 16 differentiated thyroid cancer tissues, TACC3 mRNA levels were found, with respect to normal matched tissues, reduced by twofold in 56% of cases and increased by twofold in 44% of cases. In the same tissues, a correlation between the expression of the TACC3 and Aurora-A mRNAs was observed. TACC3 and Aurora-A interact in vivo in thyroid cells and both proteins localized onto the mitotic structure of thyroid cells. Finally, TACC3 localization on spindle microtubule was no more observed following the inhibition of Aurora kinase activity by VX-680. We propose that Aurora-A and TACC3 interaction is important to control the mitotic spindle organization required for proper chromosome segregation.     

Retinoic acid and retinoid X receptors are differentially expressed in thyroid cancer and thyroid carcinoma cell lines and predict response to treatment with retinoids

Therapy for patients with advanced thyroid carcinoma is limited. Clinical and in vitro studies suggest that some patients with advanced thyroid cancer may respond to therapy with retinoic acid. mRNA expression of the six retinoic acid (RAR) and retinoid X receptor (RXR) isoforms (RARalpha, -beta, -gamma and RXRalpha, -beta, -gamma) was measured in four human thyroid cell lines, and protein expression was subsequently measured in 10 thyroid cancer cell lines. Two isoforms, RARbeta and RXRgamma, were differentially expressed in the four cell lines. Comparison of 10 thyroid tumors and matched normal thyroid tissue confirmed differential tumor expression of RARbeta and RXRgamma and lack of the RXRgamma isoform in normal thyroid tissue. Cell lines expressing both RARbeta and RXRgamma demonstrated significant growth suppression when treated with retinoids, whereas cell lines lacking these isoforms were unaffected. Expression of RARbeta, the isoform associated with suppression of tumor growth in other cancer types, was not affected by treatment with retinoids in the thyroid cancer cell lines. LG346 increased apoptosis and decreased cells in the S-phase in an anaplastic carcinoma cell line, suggesting that this retinoid causes growth suppression of these cells by multiple mechanisms. In summary, we identified the RARbeta and RXRgamma isoform to be differentially expressed in thyroid cancer cell lines and tumor tissue. These isoforms seem to predict response to retinoid therapy in thyroid cancer cell lines.     

Erythropoietin in thyroid cancer

Erythropoietin (Epo) and the epo-receptor (EpoR) have been implicated in tumor growth, invasion and metastasis. We previously demonstrated Epo and EpoR expression in a small group of archived papillary thyroid cancers (PTC), but were unable to examine functional integrity using formalin-fixed tissues. In the present study, we examined the in vitro expression, induction and function of Epo and EpoR in papillary (NPA), follicular (WRO) and anaplastic (ARO-81) thyroid cancer cells. We found that all three cell lines expressed Epo and EpoR mRNA and that the hypoxia-mimetic cobalt induced Epo expression in all cell lines. None of the growth factors we examined (thyrotropin, vascular endothelial growth factor, IGF-I, or human Epo) altered Epo or EpoR gene expression. Importantly, however, administration of Epo to NPA but not WRO cells resulted in significant alterations in the expression of several mitogenic genes including cyclooxygenase-2 (COX-2), beta-casein (CSN2), wild type p53-induced gene-1 (WIG1) and cathepsin D (CTSD). Epo treated ARO-81 cells only had an increase in CSN2 expression. We conclude that Epo and EpoR are expressed by thyroid cancers and that stimulation of the Epo/EpoR signal pathway results in changes that could impact on the clinical behavior of thyroid cancers.     

Cortistatin-14 inhibits cell proliferation of human thyroid carcinoma cell lines of both follicular and parafollicular origin

Cortistatin (CST-14, Pro-c[Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Ser-Ser-Cys]-Lys-NH2), a neuropeptide member of the SRIH family, binds to all 5 SRIH receptor (sst) subtypes, but also possesses a significant binding affinity to GH secretagogue receptors (GHS-R), which have been reported to mediate the antiproliferative activity of GHS on thyroid cancer cells. The effect of CST-14 on cell proliferation was studied in 3 different human thyroid carcinoma cell lines of follicular origin (N-PAP, WRO, ARO) and in one thyroid medullary carcinoma cell line (TT). CST-14 1 pM determined a significant inhibition of cell proliferation in TT, N-PAP and WRO cells and this effect was dose-dependent and more pronounced than that displayed by SRIH-14 (Ala-Gly-c[Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Thr-Ser-Cys]-OH) treatment. To a minor extent, CST-14, but not SRIH-14, also temporary inhibited ARO cell proliferation. By immunofluorescence, sst2, sst3 and sst5 have been demonstrated in TT cells, whereas types 3 and 5 only were expressed in N-PAP and WRO cells, and no sst subtype was found in ARO cells. The presence of both GHS-Rla and lb mRNA has been studied and demonstrated in the TT medullary carcinoma cell line, whereas follicular derived cell lines were already known to express GHS binding sites. Addition of EP-80874 (D-Mrp-c[D-Cyspyridilalanyl3-D-Trp-Lys-Val-Cys]-Mrp-NH2), a synthetic peptide that binds to SRIH and GHS-R, completely abolished the antiproliferative effects of CST-14 or SRIH-14 on sst/GHS-R positive thyroid carcinoma cell lines (WRO, N-PAP and TT). EP-80874 was also able to antagonize the inhibitory activity of CST-14 on the growth of cells (ARO) expressing GHS-R but not sst. Taken together, these data firstly demonstrate that EP-80874 has a mixed SRIH/CST antagonist activity and suggest that the oncostatic effect of CST-14 on thyroid cancer cells could be mediated by both sst and/or GHS-R.     

Enhanced expression of nicotinamide N-methyltransferase in human papillary thyroid carcinoma cells

To gain an understanding of the molecular pathogenesis of thyroid cancer, we used DNA microarray to study the expression profiles of 10 different human thyroid carcinoma cell lines. These included papillary lines BHP 2-7, BHP 7-13, BHP 10-3, BHP 18-21, NPA 87, and TPC1; anaplastic lines ARO 81-1 and DRO 90-1; follicular line WRO 82-1; and medullary line HRO 85-1. Among the genes with increased expression in the cancer cell lines, a gene coding for nicotinamide N-methyltransferase (NNMT) was identified for being highly expressed only in the papillary cell lines. NNMT catalyzes N-methylation of nicotinamide and other structurally related compounds and is highly expressed in the human liver. The results were further confirmed by semiquantitative RT-PCR and Northern blot analysis. NNMT catalytic activities were determined in all of the cells described above and in additional cell lines. Significantly higher NNMT enzyme activities were detected in eight of 10 of the papillary lines and three of six of the follicular cell lines tested. Normal thyroid tissue, thyroid primary cultures, anaplastic cancer cells, and medullary cancer cells showed no or low enzyme activity. Immunohistochemical staining for NNMT of human thyroid specimens showed strong and abundant cytoplasmic reactions in the sections of papillary carcinomas, and weak or scanty reaction in the normal thyroid tissues. These results indicate that NNMT is a potential biomarker for papillary thyroid carcinoma.     

Transforming events in thyroid tumorigenesis and their association with follicular lesions

Thyroid tumors comprise a broad spectrum of neoplastic phenotypes, and distinct molecular events have been implicated in their pathogenesis. Pituitary tumor transforming gene, originally isolated from GH(4) pituitary cells, is tumorigenic in vivo, regulates basic fibroblast growth factor secretion, and is homologous to a securin inhibitor of chromatid separation. Pituitary tumor transforming gene 1 is expressed at low levels in several normal human tissues and is abundantly expressed in neoplasms, including colorectal carcinoma, where pituitary tumor transforming gene expression correlated highly with tumor invasiveness. As pituitary tumor transforming gene is regulated by E and as thyroid cancer shows a strong female preponderance, we examined pituitary tumor transforming gene 1 expression and action in human thyroid tumors and in normal human and rat thyroid cells. Increased pituitary tumor transforming gene 1 expression was evident early in thyroid tumors and was most abundantly expressed in a subset of thyroid hyperplasia, follicular adenomas, and follicular carcinomas (1.8-fold; P < 0.0001). Pituitary tumor transforming gene 1 overexpression in rat FRTL5 thyroid cells and in primary human thyroid cell cultures causes in vitro transformation and produces a dedifferentiated neoplastic phenotype. As pituitary tumor transforming gene 1 was abundantly overexpressed in follicular adenoma and follicular carcinoma, we propose that pituitary tumor transforming gene overexpression may play a role in the early molecular events leading to divergent development of follicular and papillary carcinoma.     

Reestablishment of in vitro and in vivo iodide uptake by transfection of the human sodium iodide symporter (hNIS) in a hNIS defective human thyroid carcinoma cell line.

Uptake of iodide is a prerequisite for radioiodine therapy in thyroid cancer. However, loss of iodide uptake is frequently observed in metastasized thyroid cancer, which may be explained by diminished expression of the human sodium iodide symporter (hNIS). Strategies to restore iodide uptake in thyroid cancer include the exploration of hNIS gene transfer into hNIS defective thyroid cancer. In this study, we report the stable transfection of a hNIS expression vector into the hNIS defective follicular thyroid carcinoma cell line FTC133. Stablely transfected colonies exhibited high uptake of Na125I, which could be blocked completely with sodiumperchlorate. hNIS mRNA expression corresponded with iodide uptake in semiquantitative polymerase chain reaction. Iodide uptake was maximal after 60 minutes, whereas iodide efflux was complete after 120 minutes. hNIS transfected FTC133 and control cell lines injected subcutaneously in nude mice formed tumors after 6 weeks. Iodide uptake in the hNIS transfected tumor was much higher than in the nontransfected tumor, which corresponded with hNIS mRNA expression in tumors.     

Papillary and follicular thyroid cancer. Prognostic factors in 1,578 patients

This report from the Canadian survey of thyroid cancer describes 1,074 patients with papillary thyroid cancer and 504 with follicular thyroid cancer followed for four to 24 years. The study groups included more patients with "advanced" disease and fewer with "early" disease than in the general population because these patients were referred to radiotherapy cancer centers, sometimes routinely, but often because referring physicians believed that certain clinical features indicated the need for additional treatment. Although this report is subject to all the problems of retrospective studies, a careful assessment of the pretreatment extent of disease combined with a long follow-up period has allowed an analysis of prognostic factors with considerable confidence. Univariate analysis of 12 possible prognostic factors (excluding treatment) demonstrated that nine of them were of statistical significance: postoperative status, age at diagnosis, extrathyroidal invasion, distant metastases, nodal involvement, differentiation, sex, tumor size, and pathologic type (in descending order of importance). Multivariate analysis was carried out using cause-specific survival rates. Independently important prognostic factors at initial treatment were age at diagnosis, extrathyroidal invasion, and degree of differentiation histologically for papillary cancers; and extrathyroidal invasion, distant metastases, primary tumor size, nodal involvement, age at diagnosis, and postoperative status for follicular cancers. The prognostic factors for tumor recurrence were quite different for the papillary and follicular cancers and ranked differently for the two groups.