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

Novel nomogram to predict risk of bone metastasis in newly diagnosed thyroid carcinoma: a population-based study

Background

The aim of this study was to develop and validate a visual nomogram for predicting the risk of bone metastasis (BM) in newly diagnosed thyroid carcinoma (TC) patients.

Methods

The demographics and clinicopathologic variables of TC patients from 2010 to 2015 in the Surveillance, Epidemiology and End Results (SEER) database were retrospectively reviewed. Chi-squared (χ2) test and logistic regression analysis were performed to identify independent risk factors. Based on that, a predictive nomogram was developed and validated for predicting the risk of BM in TC patients. The C-index was used to compute the predictive performance of the nomogram. Calibration curves and decision curve analysis (DCA) were furthermore used to evaluate the clinical value of the nomogram.

Results

According to the inclusion and exclusion criteria, the data of 14,772 patients were used to analyze in our study. After statistical analysis, TC patients with older age, higher T stage, higher N stage, poorly differentiated, follicular thyroid carcinoma (FTC) and black people had a higher risk of BM. We further developed a nomogram with a C-index of 0.925 (95%CI,0.895–0.948) in the training set and 0.842 (95%CI,0.777–0.907) in the validation set. The calibration curves and decision curve analysis (DCA) also demonstrated the reliability and accuracy of the clinical prediction model.

Conclusions

The present study developed a visual nomogram to accurately identify TC patients with high risk of BM, which might help to further provide more individualized clinical decision guidelines.

FUT7 promotes the malignant transformation of follicular thyroid carcinoma through α1,3-fucosylation of EGF receptor

Aberrant protein glycosylation is involved in many diseases including cancer. This study investigated the role of fucosyltransferase VII (FUT7) in the progression of follicular thyroid carcinoma (FTC). FUT7 expression was found to be upregulated in FTC compared to paracancerous thyroid tissue, and in FTC with T2 stage of TMN classification compared to FTC with T1 stage. FUT7 overexpression promoted cell proliferation, epithelial-mesenchymal transition (EMT), and the migration and invasion of primary FTC cell line FTC-133. Consistently, FUT7 knock-down inhibited cell proliferation, EMT, as well as the migration and invasion of the metastatic FTC cell line FTC-238. Mechanistic investigation revealed that FUT7 catalyzed the α1,3-fucosylation of epidermal growth factor receptor (EGFR) in FTC cells. The extent of glycan α1,3-fucosylation on EGFR was positively correlated with the activation of EGFR in the presence/absence of epidermal growth factor (EGF) treatment. Furthermore, FUT7 was shown to enhance EGF-induced progression of FTC cells through mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathways. These findings provide a new perspective on FUT7 that may be a novel diagnostic and therapeutic target of FTC.

Bone metastases in thyroid cancer

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Osseous metastases (OMs) occur in only 4% of all thyroid cancer patients but are associated with greatly increased morbidity and mortality.

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OMs are about twice as frequent in follicular, hurthle cell, and medullary thyroid cancers as compared to papillary thyroid cancers.

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OMs are often lytic, triggered via activation of osteoclasts by tumor cells in a “vicious cycle”.

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OMs are often initially asymptomatic, but associated with eventual skeletal related events in >75%.

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Early identification of OMs, preemptive treatment with antiresorptive agents, and aggressive treatment of focal lesions before crisis are key.

Whereas preemptive screening for the presence of lymph node and lung metastases is standard-of-care in thyroid cancer patients, bone metastases are less well studied and are often neglected in thyroid cancer patient surveillance. Bone metastases in thyroid cancer are, however, independently associated with poor/worse prognosis with a median overall survival from detection of only 4 years despite an otherwise excellent prognosis for the vast majority of thyroid cancer patients. In this review we summarize the state of current knowledge as pertinent to bony metastatic disease in thyroid cancer, including clinical implications, impacts on patient function and quality of life, pathogenesis, and therapeutic opportunities, proposing approaches to patient care accordingly. In particular, bone metastasis pathogenesis appears to reflect cooperatively between cancer and the bone microenvironment creating a “vicious cycle” of bone destruction rather than due exclusively to tumor invasion into bone. Additionally, bone metastases are more frequent in follicular and medullary thyroid cancers, requiring closer bone surveillance in patients with these histologies. Emerging data also suggest that treatments such as multikinase inhibitors (MKIs) can be less effective in controlling bone, as opposed to other (e.g. lung), metastases in thyroid cancers, making special attention to bone critical even in the setting of active MKI therapy. Although locoregional therapies including surgery, radiotherapy and ablation play important roles in palliation, antiresorptive agents including bisphosphonates and denosumab appear individually to delay and/or lessen skeletal morbidity and complications, with dosing frequency of every 3 months appearing optimal; their early application should therefore be strongly considered.

Thyroid and bone

This article provides a summary of the numerous interactions between the thyroid gland and the skeleton, in the normal state, in disorders of thyroid function and as a result of thyroid malignancy. It recaps the current understanding of bone growth and development in the endochondral growth plate and the normal mechanisms of mature bone remodeling. The actions of thyroid hormones on these processes are described, and the clinical impact of thyroid disorders and their treatments on the bone are summarized. Finally, our current understanding of the physiology of bone metastases from thyroid cancer is covered.

A multi-gene approach to differentiate papillary thyroid carcinoma from benign lesions: gene selection using support vector machines with bootstrapping

Selection of novel molecular markers is an important goal of cancer genomics studies. The aim of our analysis was to apply the multivariate bioinformatical tools to rank the genes - potential markers of papillary thyroid cancer (PTC) according to their diagnostic usefulness. We also assessed the accuracy of benign/malignant classification, based on gene expression profiling, for PTC. We analyzed a 180-array dataset (90 HG-U95A and 90 HG-U133A oligonucleotide arrays), which included a collection of 57 PTCs, 61 benign thyroid tumors, and 62 apparently normal tissues. Gene selection was carried out by the support vector machines method with bootstrapping, which allowed us 1) ranking the genes that were most important for classification quality and appeared most frequently in the classifiers (bootstrap-based feature ranking, BBFR); 2) ranking the samples, and thus detecting cases that were most difficult to classify (bootstrap-based outlier detection). The accuracy of PTC diagnosis was 98.5% for a 20-gene classifier, its 95% confidence interval (CI) was 95.9-100%, with the lower limit of CI exceeding 95% already for five genes. Only 5 of 180 samples (2.8%) were misclassified in more than 10% of bootstrap iterations. We specified 43 genes which are most suitable as molecular markers of PTC, among them some well-known PTC markers (MET, fibronectin 1, dipeptidylpeptidase 4, or adenosine A1 receptor) and potential new ones (UDP-galactose-4-epimerase, cadherin 16, gap junction protein 3, sushi, nidogen, and EGF-like domains 1, inhibitor of DNA binding 3, RUNX1, leiomodin 1, F-box protein 9, and tripartite motif-containing 58). The highest ranking gene, metallophosphoesterase domain-containing protein 2, achieved 96.7% of the maximum BBFR score.

Perspectives and limitations of microarray-based gene expression profiling of thyroid tumors

Microarray technology has become a powerful tool to analyze the gene expression of tens of thousands of genes simultaneously. Microarray-based gene expression profiles are available for malignant thyroid tumors (i.e., follicular thyroid carcinoma, and papillary thyroid carcinoma), and for benign thyroid tumors (such as autonomously functioning thyroid nodules and cold thyroid nodules). In general, the two main foci of microarray investigations are improved understanding of the pathophysiology/molecular etiology of thyroid neoplasia and the detection of genetic markers that could improve the differential diagnosis of thyroid tumors. Their results revealed new features, not known from one-gene studies. Simultaneously, the increasing number of microarray analyses of different thyroid pathologies raises the demand to efficiently compare the data. However, the use of different microarray platforms complicates cross-analysis. In addition, there are other important differences between these studies: 1) some studies use intraindividual comparisons, whereas other studies perform interindividual comparisons; 2) the reference tissue is defined as strictly nonnodular healthy tissue or also contains benign lesions such as goiter, follicular adenoma, and hyperplastic nodules in some studies; and 3) the widely used Affymetrix GeneChip platform comprises several GeneChip generations that are only partially compatible. Moreover, the different studies are characterized by strong differences in data analysis methods, which vary from simple empiric filters to sophisticated statistic algorithms. Therefore, this review summarizes and compares the different published reports in the context of their study design. It also illustrates perspectives and solutions for data set integration and meta-analysis, as well as the possibilities to combine array analysis with other genetic approaches.

Differential effects of cetuximab and AEE 788 on epidermal growth factor receptor (EGF-R) and vascular endothelial growth factor receptor (VEGF-R) in thyroid cancer cell lines

This study evaluated the role of EGF and the effects of EGF-targeting drugs (Cetuximab, AEE 788) on growth, apoptosis, and autocrine VEGF-secretion of thyroid cancer (TC) cells. Autocrine activation of the epidermal growth factor receptor (EGF-R) is commonly regarded to contribute to the malignant phenotype of TC cells and may therefore represent a rational therapeutic target. Out of a number of TC cell lines two anaplastic (Hth74, C643), one follicular (FTC133), and one papillary thyroid cancer cell line (TPC1) were analyzed in depth for VEGF-R-and EGF-R-expression, basal and EGF-stimulated (1-100 ng/ml) VEGF protein secretion and proliferation. Subsequently the antiprolifereative and antiangiogenic effect of cetuximab (Erbitux), a monoclonal antibody that blocks the EGF-R and AEE 788, a novel dual-kinase inhibitor of EGF-R and VEGF-R were assessed, and the downstream EGF-R signal transduction was analyzed by means of detecting phosphorylated pEGF-R, pVEGF-R, pAkt, and p-MAPK. EGF stimulated VEGF-mRNA expression and protein secretion in all TC cell lines. The EGF-R antagonist Cetuximab consistently decreased VEGF secretion in all TC cell lines (min. 15%, n.s. in C643 cells and max. 90% in Hth74 cells, P < 0.05), but did not affect tumor cell proliferation in vitro. In contrast, the EGF-R- and VEGF-R-kinase inhibitor AEE 788 not only reduced VEGF secretion (min. 55%, P < 0.05 in C643 and max. 75%, P < 0.05, in FTC133), but also exhibited a dose-dependent inhibition of tumor cell proliferation (min. 75%, P < 0.05 in C643 and max. 95%, P < 0.05 in Hth74) and was a potent inductor of apoptosis in two of four TC cell lines. These effects were always accompanied by reduced levels of pEGF-R, pVEGF-R, pAkt, and pMAPK. Although inhibition of the EGF-receptor by Cetuximab potently disrupts autocrine secretion of VEGF, only the concurrent inhibition of the VEGF- and EGF receptor, e.g., by AEE 788 induces reduced proliferation and apoptosis in vitro. This suggests a particular rationale for the use of tyrosine kinase inhibitors with dual modes of action such as AEE 788 in thyroid cancer.

Contemporary diagnostic approach to the thyroid nodule

Thyroid nodules are common, with an estimated incidence of 5%-10% in the United States. The current gold standard for diagnosis is fine needle aspiration biopsy (FNAB). The incidence of indeterminate diagnoses varies from 10% to 25%. Surgical resection is usually indicated to exclude the diagnosis of cancer in these patients. However, only a minority (about 20%) of indeterminate thyroid nodules actually harbor a malignancy, resulting in surgery for diagnostic purposes alone in many patients. The increased detection of benign nodules and microcarcinomas reinforces the need for improved non-operative methods to differentiate benign from malignant disease and discriminate low-risk from high-risk cancers. In this article we present a current, rational diagnostic approach to the patient with a thyroid nodule, evaluate new advances including thyroid genomic and predictor models, and propose the development of prospective trials to incorporate these new additions into clinical decision making. Given how many questions still exist for patients with thyroid nodules, partnership and collaboration, or the "bench to bedside" concept should find its way into most every thyroid surgeon and endocrinologist's lexicon.

Immunohistochemical Analysis of Survivin Expression in Thyroid Follicular Adenoma and Carcinoma

Survivin is one of the 8 members of human inhibitor of apoptosis , which is differentially expressed in cancerous/transformed cells versus normal differentiated tissues. This retrospective study of thyroid histologic samples aimed to assess the clinical usefulness of survivin immunostaining for discrimination between follicular adenoma and carcinoma of thyroid. Immunohistochemical staining for survivin was performed on 41 lesions from patients who had undergone surgery for either follicular adenoma or carcinoma of thyroid. Survivin expression was significantly (P < 0.005) higher in the cases that received a diagnosis of carcinoma in comparison with follicular adenomas cases. Odds ratio of follicular carcinoma for survivin expression was 21.375 (95% CI: 3.283 to 139.177). Our results showed potential value of survivin in discrimination between follicular thyroid adenoma and follicular thyroid carcinoma. We conclude that survivin is a potential candidate for further investigation in the proper histologic diagnosis of thyroid cancers.

Meta-analysis and meta-review of thyroid cancer gene expression profiling studies identifies important diagnostic biomarkers

PURPOSE

An estimated 4% to 7% of the population will develop a clinically significant thyroid nodule during their lifetime. In many cases, preoperative diagnoses by needle biopsy are inconclusive. Thus, there is a clear need for improved diagnostic tests to distinguish malignant from benign thyroid tumors. The recent development of high-throughput molecular analytic techniques should allow the rapid evaluation of new diagnostic markers. However, researchers are faced with an overwhelming number of potential markers from numerous thyroid cancer expression profiling studies.

MATERIALS AND METHODS

To address this challenge, we have carried out a comprehensive meta-review of thyroid cancer biomarkers from 21 published studies. A gene ranking system that considers the number of comparisons in agreement, total number of samples, average fold-change and direction of change was devised.

RESULTS

We have observed that genes are consistently reported by multiple studies at a highly significant rate (P < .05). Comparison with a meta-analysis of studies reprocessed from raw data showed strong concordance with our method.

CONCLUSION

Our approach represents a useful method for identifying consistent gene expression markers when raw data are unavailable. A review of the top 12 candidates revealed well known thyroid cancer markers such as MET, TFF3, SERPINA1, TIMP1, FN1, and TPO as well as relatively novel or uncharacterized genes such as TGFA, QPCT, CRABP1, FCGBP, EPS8 and PROS1. These candidates should help to develop a panel of markers with sufficient sensitivity and specificity for the diagnosis of thyroid tumors in a clinical setting.

Novel molecular markers in well-differentiated thyroid cancers

Conventional cytopathology is an excellent tool for distinguishing benign from malignant thyroid nodules with high sensitivity and specificity. However, significant numbers of cases are indeterminate, resulting in many ultimately unnecessary diagnostic thyroidectomies. Numerous molecular markers have been studied in an attempt to improve the diagnostic accuracy of thyroid fine-needle aspiration cytology. Several markers, such as galectin-3 and thyroid peroxidase, have been extensively assessed and shown not only to differentiate malignant tumors from benign thyroid lesions with high sensitivity and specificity, but also to identify tumors associated with poor outcome. More recently, four other genes (PTTG, PBF, BRAF and MUC1) have been identified that show real promise as potential molecular markers in thyroid cancer, offering discrimination between tumor subtypes and providing valuable prognostic information. However, larger, well-controlled studies are needed before their introduction into routine clinical practice. The search for molecular markers represents one of the most exciting areas in translational thyroid cancer research. We are optimistic that molecular markers will be used in the near future as adjuncts to conventional histological techniques to improve diagnostic accuracy of fine-needle aspiration cytology for thyroid lesions, particularly those that are cytologically indeterminate.

Dual Epidermal Growth Factor Receptor and Vascular Endothelial Growth Factor Receptor Inhibition with NVP-AEE788 for the Treatment of Aggressive Follicular Thyroid Cancer

PURPOSE

Patients with radioiodine-resistant follicular thyroid cancer (FTC) have a poor prognosis, if metastasized, with currently available treatment modalities. Epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF) and their receptors (EGFR and VEGFR) have been reported to be overexpressed in FTC and have been implicated in FTC development. We hypothesized that inhibiting the phosphorylation of EGFR and VEGFR by treatment with NVP-AEE788 (AEE788), a novel dual specific EGFR and VEGFR inhibitor, either alone or in combination with paclitaxel, would inhibit the growth of FTC xenografts in an orthotopic nude mouse model.

EXPERIMENTAL DESIGN

To confirm previous reports, EGF and EGFR expression and vascularity were analyzed in human samples of FTC, Hürthle cell carcinoma, and normal thyroid tissues. EGFR expression in four FTC cell lines was measured using Western blotting. The antitumor effect of AEE788 on FTC cells in vitro was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays and Western blotting. The effect of AEE788, alone and in combination with paclitaxel, on FTC tumor growth in an orthotopic nude mouse model was also investigated. Immunohistochemical analysis of EGFR and VEGFR signaling status, cell proliferation, apoptosis, and microvessel density was done.

RESULTS

EGF, EGFR, and vascularity were increased in human thyroid tumor samples and EGFR was increased in FTC cells. AEE788 inhibited FTC cell growth in vitro and reduced the phosphorylation status of EGFR, VEGFR, and two downstream targets, AKT and mitogen-activated protein kinase, in FTC cells. AEE788 alone and, to a greater extent, AEE788 plus paclitaxel suppressed FTC tumor growth in the thyroids of nude mice.

CONCLUSION

Dual inhibition of EGFR and VEGFR by AEE788 could represent a novel approach to the treatment of radioiodine-resistant FTC.

Gene-expression profiling in differentiated thyroid cancer – a viable strategy for the practice of genomic medicine?

Thyroid neoplasias have been largely ignored as an active field of investigation due to the overall favorable prognosis of differentiated nonmedullary thyroid cancers. However, differentiated thyroid cancers have the highest estimated annual percentage increase in incidence amongst all cancer sites. Furthermore, no significant progress has been made to improve survival, especially for advanced disease. Compounding the problem, there remains a lack of highly accurate preoperative markers or molecular-based predictive models to differentiate benign from malignant follicular neoplasias, thus we continue to rely upon surgery for diagnostic purposes in this subset of patients. Therefore, new approaches are necessary to identify potential novel diagnostic, prognostic and therapeutic algorithms, which would not only allow accurate early diagnosis but also personalized patient management, with clinical management and surveillance tailored according to the genetic signature of the patient. The advent of modern genomic technologies, such as global gene-expression profiling, may begin to provide the data required for the evidence-based practice of genomic medicine as it relates to thyroid neoplasia. However, it is already clear that genomic technology alone is insufficient to fully achieve this vision.

Antivascular Therapy of Human Follicular Thyroid Cancer Experimental Bone Metastasis by Blockade of Epidermal Growth Factor Receptor and Vascular Growth Factor Receptor Phosphorylation

Patients suffering from bone metastases of follicular thyroid carcinoma (FTC) have a poor prognosis because of the lack of effective treatment strategies. The overexpression of epidermal growth factor receptor (EGFR) associated with increased vascularity has been implicated in the pathogenesis of FTC and subsequent bone metastases. We hypothesized that inhibiting the phosphorylation of the EGFR and vascular endothelial growth factor receptor (VEGFR) by AEE788, a dual tyrosine kinase inhibitor of EGFR and VEGFR, in combination with paclitaxel would inhibit experimental FTC bone lesions and preserve bone structure. We tested this hypothesis using the human WRO FTC cell line. In culture, AEE788 inhibited the EGF-mediated phosphorylation of EGFR, VEGFR2, mitogen-activated protein kinase, and Akt in culture. AEE788, alone and in combination with paclitaxel, inhibited cell growth and induced apoptosis. When WRO cells were injected into the tibia of nude mice, tumor and endothelial cells within the lesions expressed phosphorylated EGFR, VEGFR, Akt, and mitogen-activated protein kinase that were inhibited by the oral administration of AEE788. Therapy consisting of orally given AEE788 and i.p. injected paclitaxel induced a high level of apoptosis in tumor-associated endothelial cells and tumor cells with the inhibition of tumor growth in the bone and the preservation of bone structure. Collectively, these data show that blocking the phosphorylation of EGFR and VEGFR with AEE788 combined with paclitaxel can significantly inhibit experimental human FTC in the bone of nude mice.

Angiogenesis as an indicator of metastatic potential in papillary thyroid carcinoma

Angiogenesis is new blood vessel formation, a process that can lead to tumor development. Microvessel count has been correlated to metastasis in some neoplasias.

PURPOSE

To determine if measurement of microvessel density is useful in predicting metastasis to the cervical lymph node and prognosis in patients with papillary thyroid carcinoma.

METHODS

A retrospective analysis was performed in 30 patients that had undergone total thyroidectomy. They were divided in 2 groups of 15 patients--with and without metastatic disease. Immunohistochemistry was used to detect expression of CD34 in archival paraffin-embedded papillary thyroid tumors, and microvessel density was calculated based on it. Association between microvessel density and the presence of metastasis, according to histological subtype, disease recurrence, and AMES prognostic index groups was determined through statistical analysis.

RESULTS

The median microvessel density for the patient group without metastasis (200.0 microvessels/mm2) was apparently, but not significantly, less than that observed among metastatic disease patients (254.4 microvessels/mm2) (P=.20). When papillary carcinoma subtypes were analyzed, this difference became significant (P=02). The follicular variant exhibited a greater microvessel density than the other subtypes, independent of metastasis presence. There was an apparent, but not significant, tendency for a larger median microvessel density in the group of patients that presented recurrence (294.4 microvessels/mm2 vs 249.6 microvessels/mm2, P=.11). There was no relationship between risk level and microvessel density: in the low- and high-risk groups, the median MVD was 304.0 microvessels/mm2 and 229.6 microvessels/mm2, respectively (P=.27).

CONCLUSIONS

The results suggest that angiogenesis is more intense among metastatic tumors in the classic and the tall cell variants, indicating that microvessel count can be an indicator of the potential for metastasis in these subtypes of papillary thyroid carcinoma. Patients that developed recurrent disease had a tendency to exhibit higher angiogenesis; however, there was no association between microvessel density and the AMES prognostic index.

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.

Gene expression profiles reveal that DCN, DIO1, and DIO2 are underexpressed in benign and malignant thyroid tumors

To investigate the molecular events involved in the pathogenesis and/or progression of thyroid tumors, we compared the gene expression profiles of three thyroid carcinoma cell lines, which represent major tumor subtypes of thyroid cancer and normal thyroid tissue. Using cDNA array methodology, we investigated the expression of 1807 open reading frame expressed sequence tags (ORESTES), selected from head and neck tumor libraries generated through the Brazilian Human Cancer Project-LICR/FAPESP. We found that 505 transcripts were differentially expressed in the thyroid carcinoma cell lines. Using a more stringent criterion, transcripts underexpressed or overexpressed more than fivefold in 1 of 3 or 3 of 3 carcinoma cell lines, a list of 55 ESTs were detected. Five candidate genes were further validated by quantitative polymerase chain reaction (qPCR) in an independent set of 52 thyroid tumors and 22 matched normal thyroid tissues. DCN was found underexpressed in a high percentage of the follicular thyroid adenomas, follicular thyroid carcinomas, and follicular variant of papillary thyroid carcinomas. DIO1 and DIO2 were underexpressed in nearly all papillary thyroid carcinomas. These genes not only could help to better define a tumor signature for thyroid tumors, but may, in part, also become useful as potential targets for thyroid tumor treatment.

Proteomic analysis of human thyroid cell lines reveals reduced nuclear localization of Mn-SOD in poorly differentiated thyroid cancer cells

Differential protein arrays between nuclear extracts of human thyroid cell lines obtained from tumors with different degree of differentiation were exploited to define molecular alterations occurring during thyroid tumor progression. Nuclear extracts from the well differentiated TPC-1 (from papillary carcinoma) and the poorly differentiated ARO (from anaplastic carcinoma) cells showed an overall similar pattern of protein expression as revealed by two-dimensional gel electrophoresis analysis. However, manganese-superoxide dismutase (Mn-SOD) was clearly identified by mass spectrometry procedures as significantly less expressed in ARO compared to TPC-1 cells. A reduced expression of Mn-SOD in the nuclear compartment was confirmed by Western blot and immunofluorescence analysis. A similar expression pattern of nuclear Mn-SOD was detected by immunohistochemistry in human thyroid tumors, with the lowest or absent detection in anaplastic carcinomas. Moreover, the levels of nuclear Mn-SOD in tumor cells were lower than in the normal thyrocytes. These data indicate that an altered nuclear expression of Mn-SOD parallels, together with changes in other elements of the antioxidant protective system, the loss of differentiation occurring during the progression of thyroid tumors.

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.

Anaplastic transformation of thyroid cancer: review of clinical, pathologic, and molecular evidence provides new insights into disease biology and future therapy

BACKGROUND

Anaplastic thyroid cancer ranks among the most lethal of all human malignancies. Its rarity and rapidly fatal course have made it a difficult cancer to both study and treat. Unfortunately, there has been little progress in the management and control of this malignancy. Anaplastic transformation, or the intratumoral evolution of anaplastic carcinoma from pre-existing differentiated thyroid cancer, has become a well-accepted process, despite a limited understanding of its underlying mechanisms.

METHODS

It is through review of the literature that an understanding of the aggressive disease biology can be developed. The aim of this review is to evaluate the relevant clinical, pathologic, and molecular studies to develop an insight into the mechanisms that underlie the intratumoral molecular evolution of anaplastic thyroid carcinoma.

RESULTS/CONCLUSION

It is based on an understanding of this process that effective treatments for this aggressive malignancy are currently being developed.

New molecular methods for classification, diagnosis and therapy prediction of hematological malignancies

Normal functions of the cell are based on the precise regulation of various genes. If this strict regulation and the hierarchy of genes becomes upset due to flaws in this system, the result will be cellular dysfunction which eventually may lead to carcinogenic transformation. Two basic challenges of the classification of cancers are the discovery of new molecular markers characteristic to defined disease groups and the classification of already diagnosed or new cases into existing groups. This precise classification may open the door to tailored treatment or project the expected outcome of the disease. Today there is unlimited access available to the databases containing sequences and localization of the genes within the confines of Human Genome project. It provides significant help for the discovery of chromosome abnormalities and systematic analysis of gene expression patterns. This is important not only to understand normal functions of the cells, but it also contributes to the identification of new genes that are characteristic to given disease groups as markers and that are potential drug targets. Until the second half of the twentieth century the study of the function and regulation of genes was based on step-by-step investigation of individual genes. Regarding the fact, that the genomes of an increasing number of organisms have become known in whole or in part, numerous new techniques have been developed that facilitated the systematic analysis of gene functions. The aim of this study is to summarize the new, molecular based possibilities for classification, diagnosis and prognosis of hematological malignancies, as well as to summarize the main results of these areas.

Genes regulated by thyrotropin and iodide in cultured human thyroid follicles: analysis by cDNA microarray

Thyrotropin (TSH) regulates a number of genes in thyrocytes, leading to iodide uptake, de novo synthesis and release of thyroid hormones, and cell proliferation, accompanied by increased blood flow. At higher doses of iodide, however, the TSH-induced increases in thyroid hormone release and blood flow are downregulated, and high iodide intake occasionally worsens autoimmune thyroiditis. To elucidate the genes involved in such effects, we cultured human thyrocytes and examined genes modulated by TSH and iodide, using a cDNA microarray study, which can analyze 2400 genes in each run. When thyroid follicles were cultured with TSH for 2 days, more than 100 genes were upregulated. These genes included those for enzymes involved in carbohydrate and lipid metabolism, adenylate and guanylate cyclases, and enzyme involved in cell proliferation. When thyroid follicles were cultured with high iodide concentrations (10(-5) M) for 24 hours, more than 100 genes were upregulated. Interesting genes were interleukin-8, IFP53, 90-kd heat shock protein, osteopontin, and intercellular adhesion molecule-1. These results were confirmed by reverse transcription-polymerase chain reaction (RT-PCR) followed by Southern blot hybridization. In summary, TSH upregulated a number of genes regulating thyroid functions. It is intriguing that thyroid follicles cultured with a high iodide concentration (10(-5) M) increased the expression levels of genes capable of modulating lymphocyte functions, even though immunocompetent cells were extensively removed by the present experimental culture conditions. Although we have analyzed only approximately 6%-8% of all human genes, the cDNA microarray study is a powerful tool to elucidate the effects of TSH and iodide on thyroid function.

Cancer-specific mRNAs in thyroid carcinomas: detection, use, and their implication in thyroid carcinogenesis

Molecular-based diagnosis ofthyroid carcinomas can be more easily establishedby utilizing specific mRNAs that are expressed in a restricted manner in cancer tissues. Accordingly, several cancer-specific mRNAs in thyroid carcinomas have been identified by means of sequence specific-differential display (SS-DD), serial analysis of gene expression (SAGE) and other new techniques. By using these cancer-specific mRNAs, some new methods of preoperative diagnosis of thyroid carcinomas have been developed. In one such method, Aspiration Biopsy-Reverse Transcription-Polymerase Chain Reaction (ABRP), RNA is extracted from leftover cells within the needle used for fine needle aspiration biopsies (FNABs), thereby allowing cytological and molecular-based diagnoses to be performed simultaneously. ABRP provides both RNA information and a cytological diagnosis without further invasion to the patient. By ABRP detection of cancer-specific mRNAs, papillary, anaplastic and medullary carcinomas and a part of malignant lymphomas can be accurately diagnosed preoperatively. It remains to be clarified why cancer-specific mRNAs, especially those that are overexpressed in fetal tissues, can clearly distinguish benign tissues from carcinomas, while genomic alternations, such as mutations in the RAS or P53 gene cannot. Further, the widely accepted hypothesis of multi-step carcinogenesis cannot explain some of the clinical and experimental findings of thyroid carcinomas. Considering these facts, we propose a novel hypothesis of thyroid carcinogenesis, the "germ-cell carcinogenesis" hypothesis, in which cancer cells derive from the remnants of fetal thyroid germ cells (thyroblasts) instead of normal thyroid follicular cells.

Apoptosis: life through planned cellular death regulating mechanisms, control systems, and relations with thyroid diseases

Apoptosis is an active biologic process that represents a form of programmed cellular suicide, activated either by genetic factors or by cellular lesions caused by various extracellular traumatic agents. The alterations of its functional mechanisms control cellular homeostasis are involved in the genesis of many illnesses. There are different control systems that can both stimulate and inhibit apoptosis, such as the p53 and Bcl-2 proteins. Different injuries may cause a rapid increase in the levels of p53 and the activation of the complex mechanism which leads either to damage repair or cellular apoptosis. The concept of tumor growth as a dynamic balance between cellular development and death is well applicable to differentiated thyroid carcinomas, which are generally not highly invasive and present excellent prognosis. On the contrary, in aggressive anaplastic thyroid carcinoma there is an increase in p53, whereas in normal thyroid cells there is a high expression of Bcl-2, so as to interfere with apoptosis when physiologic hormone levels are normal. However, only some of the biomolecular mechanisms behind the genesis of thyroid tumors have been explained, and the role of apoptosis in thyroid diseases has not been well defined. This review provides information about relationship between apoptosis and thyroid diseases.