Selenium decreases thyroid cancer cell growth by increasing expression of GADD153 and GADD34.

Selenium (Se) supplementation is reported to decrease the incidence and total mortality of cancer. Whereas in vitro and in vivo studies have shown a decrease in prostate, lung, and liver cancers, this has not been shown in thyroid cancer. ARO (anaplastic), NPA (BRAF positive papillary), WRO (BRAF negative papillary), and FRO (follicular) cells treated with 150 microM seleno-l-methionine (SM) were assessed for viability at 24, 48, and 72 h. Treated FRO cells were examined for cell cycle using flow cytometry, for apoptosis using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and for gene expression using microarray. Genes identified as upregulated were confirmed by real-time PCR (RT-PCR) and proteins by Western blot analysis. SM treatment significantly decreased the proliferation of all cell lines. TUNEL assay showed no evidence of apoptosis, and flow cytometry showed a significant cell-cycle arrest in S (271% increase, P = 0.006) and G2/M (61% increase, P = 0.002) compared to control. Microarray revealed 21 differentially expressed genes with greater than twofold change. A relative overexpression of growth arrest and DNA damage inducible (GADD)34 and GADD153 in treated cells was confirmed with RT-PCR and Western blot. SM inhibits thyroid cancer cell proliferation through a time dependent upregulation of the GADD family of genes and arrest in S and G2/M phases of the cell cycle. This is the first report of selenium induced inhibition of thyroid cancer cell growth.

Identification of borderline thyroid tumors by gene expression array analysis.

BACKGROUND: A subset of follicular lesions of the thyroid is encapsulated similar to follicular adenomas but with partial nuclear features suggestive of papillary thyroid carcinoma (PTC), raising the possibility of biologically borderline tumors. METHODS: Gene expression profiling and advanced significance analyses were performed on 50 histologically unequivocal benign and malignant tumors, and a list of 61 differentially expressed genes was generated. By using this 61-gene list, unsupervised hierarchical and K-means cluster analyses were performed on 40 additional tumors, including 15 histologically borderline tumors, 11 benign tumors, and 14 PTCs. RESULTS: Analysis revealed 3 distinct tumor groups-benign, malignant, and intermediate. Tumors in the intermediate group (n = 15) were mostly histologic borderline tumors and had an expression profile overlapping with the benign and malignant groups. Twenty-seven genes were expressed differentially between the benign and intermediate groups, including the cyclic AMP response element-binding protein/p300-interactivator with glutamic acid/aspartic acid-rich carboxy-terminal domain 1 or CITED1 gene and the fibroblast growth factor receptor 2 or FGFR2 gene. Fourteen genes were expressed differentially between the intermediate group and malignant tumors, notably overexpression of the met proto-oncogene and of the high-mobility group adenine/thymine-hook 2 or HMGA2 gene in malignancies. Mutations of the v-raf murine sarcoma viral oncogene homolog B1 or BRAF gene were identified in 4 of 14 malignant tumors but not in benign or intermediate tumors. Patients who had either histologically or molecularly borderline tumors did not have metastasis or recurrences. CONCLUSIONS: Gene expression profiling supported the finding that encapsulated thyroid follicular lesions with partial nuclear features of PTC are biologically borderline tumors that are distinct molecularly from benign and malignant tumors.

Do benign thyroid nodules have malignant potential? An evidence-based review.

BACKGROUND: Benign thyroid tumors account for most nodular thyroid disease. Determination of whether a thyroid nodule is benign or malignant is a major clinical dilemma and underlies the decision to proceed to surgery in many patients. Although the accuracy of thyroid nodule fine-needle aspiration (FNA) has reduced the need for surgery over the years, questions regarding how to follow FNA-designated benign nodules remain unresolved. This is true at least in part because of uncertainty over whether some benign nodules harbor malignant potential. METHODS: An evidence-based review of recent clinical, pathologic, and molecular data is presented. A summary of data and observations from our own experience is also provided. RESULTS: Review of our recent 10-year experience indicates that 2% of thyroid malignancies arise within a preexisting benign thyroid nodule. In addition, both cytologic and molecular tumor markers, including Gal-3, CITED1, HBME-1, Ras, RET/PTC, and PAX8/PPAR gamma, have been identified in some histopathologically classified benign nodules. Gene expression profiling suggests that follicular adenomas and Hürthle cell adenomas have similarities to both benign and malignant tumors, suggesting that some of these tumors are premalignant. In addition, 10% of surgically excised follicular tumors are encapsulated follicular lesions with nuclear atypia, which have been termed "well-differentiated tumors of uncertain malignant potential." The data available suggest that these tumors could be precursors to carcinoma. CONCLUSION: Some benign thyroid nodules have malignant potential. Further molecular testing of these tumors can shed light on the pathogenesis of early malignant transformation.

Molecular analysis of minimally invasive follicular carcinomas by gene profiling.

BACKGROUND: While the majority of minimally invasive follicular thyroid carcinoma (MIFTC) behave like follicular adenomas, some recur or metastasize. These studies were conducted to determine if molecular profiling can enhance our understanding of MIFTC and to perhaps offer a better classification schema. METHODS: Microarray analysis was performed on 27 follicular neoplasms. Thirteen follicular adenomas (FAs) were compared with 7 widely invasive follicular thyroid carcinomas (WIFTCs) to generate a list of differentially expressed genes. Next, 7 MIFTCs were analyzed along with the other samples in a cluster analysis. The MIFTCs were then compared directly against both the adenoma and WIFTC groups to investigate genetic relatedness. RESULTS: FAs and WIFTCs have distinct genetic profiles, with 401 differentially expressed genes. The 7 MIFTCs were added to the analysis. Six of 7 of the MIFTCs were grouped with the adenomas, 4 of which created their own subgroup. When analyzed directly, MIFTCs had 223 differently expressed genes, compared with FAs, and 365, compared with WIFTCs. CONCLUSIONS: Molecular profiling illustrates that the majority of MIFTCs comprise a subclass of follicular neoplasms, and, while most MIFTCs are genetically similar to adenomas, our patient data suggest that these tumors may deserve greater suspicion of malignant potential. Gene profiling can provide insight into the molecular pathogenesis of MIFTC.

Advancing the molecular diagnosis of thyroid nodules: defining benign lesions by molecular profiling.

BACKGROUND: Thyroid nodules are common and most are benign. Previous data from our laboratory and others has suggested that gene profiling can accurately distinguish between benign and malignant thyroid nodules and provide new leads in the study of thyroid tumorigenesis. Current preoperative techniques do not permit distinction between neoplastic and hyperplastic follicular neoplasms. These studies were undertaken to determine whether benign follicular tumors could be subcategorized by molecular profiling. METHODS: Molecular profiles of 8 follicular adenomas and 8 hyperplastic nodules were analyzed by oligonucleotide microarray analysis. A list of 402 differentially expressed genes was produced based on a comparison of these two groups. Seven additional benign follicular lesions were then added to the analysis. A hierarchical clustering analysis was performed on all 23 samples, utilizing the gene list generated from the test set, to examine the groups for potential differences and the ability of the gene list to distinguish tumor types. RESULTS: Cluster analysis of all 23 samples produced two distinct groups, one containing the adenomas and one containing the hyperplastic lesions. The analysis was able to identify follicular adenomas with a sensitivity of 84.6% and a specificity of 100%. CONCLUSIONS: These data indicate that benign thyroid lesions can be separated into distinct groups through molecular profiling. Analysis of the gene list may help further the understanding of thyroid tumorigenesis. Expression profiling may ultimately allow us to distinguish potentially malignant from benign follicular nodules.

Discrimination of benign and malignant thyroid nodules by molecular profiling.

BACKGROUND: The evaluation of thyroid nodules by fine-needle aspiration has been the standard for almost 30 years, despite significant shortcomings in sensitivity and specificity. Recent data from our laboratory have suggested that molecular profiling permits the discrimination of specific types of thyroid nodules. These studies were undertaken to determine whether molecular profiling can discriminate between benign and malignant thyroid nodules with the necessary sensitivity and specificity required of a screening test. METHODS: Molecular profiles of 11 papillary thyroid carcinomas, 13 follicular variant of papillary thyroid carcinomas, 9 follicular thyroid carcinomas, and 26 benign tumors (follicular adenomas and hyperplastic nodules) were analyzed by oligonucleotide microarray analysis. A gene list was created based on 45 samples. Seventeen samples were then added to the analysis as unknowns. A hierarchical clustering analysis was performed on all 62 samples to examine the groups for potential differences and the ability of the gene list to distinguish tumor types. RESULTS: Cluster analysis of all 62 samples produced 2 distinct groups, 1 containing the carcinomas and 1 containing the benign lesions. The sensitivity for a diagnosis of cancer was 91.7% with a specificity of 96.2% (3 follicular variant of papillary thyroid carcinomas clustered with the benign lesions). The cancer gene profiles contained both known cancer-associated genes (MET, galectin-3) and previously unidentified genes. CONCLUSIONS: Molecular profiling readily distinguishes between benign and malignant thyroid tumors with excellent sensitivity and specificity. Elucidated genes may provide insight into the molecular pathogenesis of thyroid cancer. Gene profiling may significantly enhance the evaluation of thyroid nodules in the future.

Molecular profiling distinguishes papillary carcinoma from benign thyroid nodules.

Recently we identified a molecular basis for differentiating benign and malignant follicular thyroid tumors. The purpose of these studies was to determine whether molecular analysis can be used to differentiate papillary thyroid carcinomas from benign thyroid nodules. Gene expression patterns of 14 papillary thyroid carcinomas and 21 benign tumors were analyzed by oligonucleotide array analysis. The carcinomas included seven classical papillary thyroid carcinomas (PTC) and seven follicular variant of PTC (FVPTC), and the benign tumors included 14 follicular adenomas and seven hyperplastic nodules. A hierarchical clustering analysis was performed to examine the groups for potential differences. The combined PTC and FVPTC groups had a distinct gene expression profile compared with the benign lesions. The sensitivity for a diagnosis of carcinoma was 93%, with a 100% specificity (one FVPTC clustered with the benign nodules). Cancer gene profiles contained both known (Met and galectin-3) and previously unidentified genes. Gene profiling is a reliable means of distinguishing PTC, FVPTC, and benign tumors of the thyroid. These gene profiles may provide insight into the pathogenesis of papillary thyroid carcinoma and may ultimately enhance the preoperative diagnosis of thyroid nodules on a molecular basis.

Molecular analysis of Hurthle cell neoplasms by gene profiling.

BACKGROUND: Though Hurthle cell tumors are considered a variant of follicular lesions, recent data have suggested that Hurthle cell carcinomas may be more closely related to papillary thyroid carcinomas (PTCs). These studies were conducted to determine if molecular profiling can enhance our understanding of Hurthle cell neoplasms. METHODS: Thirteen Hurthle cell tumors (9 adenomas, 4 carcinomas) were analyzed with the Affymetrix HU-95 gene chips. Molecular profiles obtained were compared to 14 follicular adenomas (FAs), 7 follicular carcinomas (FCs), 10 PTCs, 11 follicular variant PTCs, and 9 hyperplastic nodules. Hierarchical cluster analysis defined potential groupings and differences among samples. RESULTS: Hurthle cell carcinomas grouped with FCs 100% of the time. Surprisingly, Hurthle cell adenomas clustered with FCs when compared to FAs and FCs in 8/9 (88%) cases. All 13 Hurthle cell lesions migrated as a distinct group separate from PTCs and FVPTCs. Finally, all Hurthle cell lesions clustered with FCs, rather than PTCs, when compared to both groups. CONCLUSIONS: Molecular profiles of Hurthle cell adenomas and carcinomas are more similar to FCs than benign lesions or PTCs. Although Hurthle cell adenomas generally behave in a benign fashion, the molecular signature of these lesions suggests a more malignant phenotype.

Classification of follicular thyroid tumors by molecular signature: results of gene profiling.

PURPOSE: Thyroid nodules are common, with a lifetime risk of developing a clinically significant thyroid nodule of 10% or higher. Preoperative diagnosis was greatly enhanced by the introduction of fine needle aspiration in the 1970s, but there has been little advancement since that time. Discrimination between benign and malignant follicular neoplasms is currently not possible by fine needle aspiration and can even be difficult after full pathologic review. The purpose of these studies is to identify genes expressed in follicular adenomas and carcinomas of the thyroid that will permit molecular differentiation of these neoplasms. EXPERIMENTAL DESIGN: Gene expression patterns of 17 thyroid follicular tumors were analyzed by oligonucleotide array analysis. Gene profiles for follicular adenomas and carcinomas were identified, and the two groups were compared for differences in expression levels. The differentially expressed genes were used to perform a hierarchical clustering analysis training set. Five follicular tumors with diagnosis undisclosed to the investigators and 2 minimally invasive carcinomas were entered into the cluster analysis as a test set to determine whether diagnosis by gene profile correlated with that obtained by pathologic evaluation. RESULTS: Thyroid follicular adenomas and carcinomas showed strikingly distinct gene expression patterns. The expression patterns of 105 genes were found to be significantly different between follicular adenoma and carcinoma. Many uncharacterized genes contributed to the distinction between tumor types. For five follicular tumors for which the final diagnosis was undisclosed, the clustering algorithm gave the correct diagnosis in all 5 cases. CONCLUSIONS: Gene profiling is a useful tool to predict the molecular diagnosis of follicular thyroid tumors. Genes were identified that reliably differentiate follicular thyroid carcinoma from adenoma. This study provides insight into genes that may be important in the molecular pathogenesis of follicular thyroid tumors, as well candidates for preoperative diagnosis of follicular thyroid carcinoma.