A preoperative diagnostic test that distinguishes benign from malignant thyroid carcinoma based on gene expression

Nódulos com diagnóstico de padrão folicular: marcadores biológicos são o futuro?

Com o uso da ultra-sonografia de alta resolução, a prevalência de nódulos tem aumentado e, conseqüentemente, o número de punção aspirativa por agulha fina (PAAF), que é o método de escolha para diagnóstico inicial. Um dos maiores dilemas clínicos para o citologista é o diagnóstico diferencial das lesões foliculares comumente agrupadas na classe padrão folicular. Neste artigo de revisão, discutiremos quais são as lesões que podem ser assim classificadas e os marcadores moleculares, identificados por nós ou por outros grupos, que são capazes de distinguir as lesões benignas das malignas.

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.

Expression microarray analysis of papillary thyroid carcinoma and benign thyroid tissue: emphasis on the follicular variant and potential markers of malignancy

The most common sub-variant of papillary thyroid carcinoma (PTC) is the so-called follicular variant (FVPTC), which is a particularly problematic lesion and can be challenging from a diagnostic viewpoint even in resected lesions. Although fine needle aspiration cytology is very useful in the diagnosis of PTC, its accuracy and utility would be greatly facilitated by the development of specific markers for PTC and its common variants. We used the recently developed Applied Biosystems 1700 microarray system to interrogate a series of 11 benign thyroid lesions and conditions and 14 samples of PTC (six with classic morphology and eight with follicular variant morphology). TaqMan(R) reverse transcriptase-polymerase chain reaction was used to validate the expression portfolios of 50 selected transcripts. Our data corroborates potential biomarkers previously identified in the literature, such as LGALS3, S100A11, LYN, BAX, and cluster of differentiation 44 (CD44). However, we have also identified numerous transcripts never previously implicated in thyroid carcinogenesis, and many of which are not represented on other microarray platforms. Diminished expression of metallothioneins featured strongly among these and suggests a possible role for this family as tumour suppressors in PTC. Fifteen transcripts were significantly associated with FVPTC morphology. Surprisingly, these genes were associated with an extremely narrow repertoire of functions, including the major histocompatibility complex and cathepsin families.

Thyroid-stimulating hormone receptor messenger ribonucleic acid measurement in blood as a marker for circulating thyroid cancer cells and its role in the preoperative diagnosis of thyroid cancer

CONTEXT

Thyroid cancer cells express TSH receptor (TSHR) mRNA, and its measurement in the circulation may be useful in the diagnosis/management of differentiated thyroid cancer (DTC).

OBJECTIVE

Our objective was to assess the diagnostic value of circulating TSHR mRNA for preoperative detection of DTC in patients with thyroid nodules.

PATIENTS

We measured TSHR mRNA levels by RT-PCR in 258 subjects: 51 healthy subjects and 207 patients (thyroid nodules, n = 180; recurrent thyroid cancer, n = 27) with fine-needle aspirations (FNA) and/or thyroid/neck surgery. Eighty-nine patients also had d-1 postoperative levels assessed.

OUTCOME MEASURES

TSHR mRNA levels were compared with FNA cytology for cancer detection preoperatively and serum thyroglobulin and/or whole-body 131I scans postoperatively.

RESULTS

Based on cytology/pathology, 88 patients had DTC and 119 had benign thyroid disease. The TSHR mRNA levels in cancer patients were significantly higher than in benign disease (P < 0.0001). At a cutoff value of 1.02 ng/microg total RNA, the TSHR mRNA correctly classified 78.7% of patients preoperatively (sensitivity = 72.0%; specificity = 82.5%). Of 131 patients with FNA and surgery, 51 were FNA positive (all cancer), 17 were FNA negative (15 benign, two cancer), and 63 were indeterminate. TSHR mRNA correctly diagnosed DTC in 16 of 24 (67%) and benign disease in 29 of 39 (74%) patients with indeterminate FNA (combined sensitivity = 90%; specificity = 80%). Combining TSHR mRNA and ultrasound features for follicular lesions correctly classified all follicular cancers and could have spared surgery in 31% of these patients with benign disease. TSHR mRNA has a short life in circulation, and normalized levels on postoperative d 1 correlated with disease-free status, whereas elevated levels predicted residual/metastatic disease.

CONCLUSIONS

TSHR mRNA measured with FNA enhances the preoperative detection of cancer in patients with thyroid nodules, reducing unnecessary surgeries, and immediate postoperative levels can predict residual/metastatic disease.

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.

A novel tumor marker, Niban, is expressed in subsets of thyroid tumors and Hashimoto's thyroiditis

Niban is a recently identified molecular marker of renal carcinogenesis in the Tsc2 gene-mutant Eker rat. Niban expression is most dramatically increased in the early stage of renal carcinogenesis and might decline during malignant progression. Niban is also expressed in various histologic types of human renal cell carcinoma. Therefore, Niban might be a good marker for renal carcinogenesis in both animal models and humans. In the present study, we examined Niban expression in various thyroid lesions by immunohistochemical staining using polyclonal rabbit antihuman Niban antibody. Normal thyroid tissue never stained for Niban. Niban was most frequently expressed in tumors with oxyphilic cytoplasm, including oxyphilic variants of papillary carcinoma (4/4 = 100%), oxyphilic variants of follicular adenoma (7/7 = 100%), and oxyphilic variants of follicular carcinoma (5/5 = 100%). Eighty-one percent (44/54) of papillary carcinoma cases, including microcarcinomas, and follicular variants were also positively stained for Niban at variable intensities. Follicular carcinomas were less frequently and less intensely stained. In nonneoplastic lesions, cells were rarely positively stained. In Hashimoto's thyroiditis, scattered cells with oxyphilic cell metaplasia were weakly Niban-positive. Reverse transcriptase-polymerase chain reaction and Western blot analysis of frozen tissue confirmed Niban expression at the molecular level in 4 cases of papillary carcinoma. Taken together, Niban expression is up-regulated in various types of thyroid tumors. We postulate that Niban expression may play an important role in the tumorigenic process of the thyroid in several scenarios. (1) Niban expression may be closely related to the carcinogenic process, especially from the early stage of papillary thyroid carcinoma. (2) Niban may be closely associated with altered mitochondrial functions in preneoplastic and neoplastic processes of the thyroid. (3) Niban may be a molecular marker of the oxyphilic phenotype under various conditions. Further functional studies of Niban will clarify the role of Niban in various thyroid lesions.

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.

Molecular determination of benign and malignant thyroid tumors

Recent molecular studies have revolutionized our understanding of the pathogenesis of thyroid tumors and particular advances have been made in three areas. First, toxic thyroid nodules, which originate from constitutive activation of thyroid-stimulating hormone receptor/Gs α signaling and represent the dominant cause of thyrotoxicosis in regions with iodine deficiency. Second, papillary thyroid cancer, the most frequent thyroid malignancy, which is characterized by a common fingerprint of constitutive mitogen-activated protein kinase activation. Importantly, this is caused by distinct genetic alterations in radiation-induced (RET/PTC, NTRK and AKAP9/BRAF rearrangements) and sporadic tumors (BRAF and RAS point mutation) and, recently, there exciting in vitro have emerged explaining the structural basis for this. These findings suggest a scenario in which the fate of a thyroid tumor is determined by the specific genetic defect at the beginning. Third, application of microarray analysis in nodular pathologies in which the oncogenic pathway is less clear, notably follicular neoplasia, has led to the identification of a number of promising genetic markers (TFF-3, Gal-3, PLAB, CCND2 and PCKD2) for the diagnostic distinction of follicular adenoma and carcinoma. In addition to the diagnostic perspective, the identification of molecular fingerprints of thyroid tumors opens novel avenues for an improved therapeutic approach; for example, selective antagonism of cell signaling in treatment-refractory thyroid cancer.

Microarray analysis of thyroid nodule fine-needle aspirates accurately classifies benign and malignant lesions

Current preoperative diagnostic procedures for thyroid nodules rely mainly on the cytological interpretation of fine-needle aspirates (FNAs). DNA microarray analysis has been shown to reliably distinguish benign and malignant thyroid nodules in surgically resected specimens, but its diagnostic potential in thyroid FNA has not been examined. In the present study, the expression profiles of 50 benign thyroid lesions and papillary thyroid carcinoma tissue samples were compared, generating a list of 25 differentially expressed genes from this training set. A test set of 22 FNA specimens was evaluated by unsupervised hierarchical cluster analysis using this gene list, and the results were compared to FNA cytology. FNA specimens were found to fall into three clusters: malignant (n = 10), benign (n = 7), and indeterminate (n = 5). The benign and malignant groups showed complete concordance with the final histological diagnosis except for one histologically benign lesion, which was rediagnosed as follicular variant of papillary thyroid carcinoma on histological review. Paired analysis between FNA and matched tissues samples illustrated adequate sampling with FNA. These results illustrate that microarray analysis of FNA is feasible and has the potential to improve the accuracy of FNA in categorizing benign from malignant lesions beyond routine cytological evaluation.

Quantitative and qualitative differences in protein expression between papillary thyroid carcinoma and normal thyroid tissue

In order to better understand basic mechanisms of tumor development and identify potential new biomarkers, we have performed difference gel electrophoresis (DIGE) and peptide mass fingerprinting on pooled protein extracts from patients with papillary thyroid carcinoma (PTC) compared with matched normal thyroid tissue. Image analysis of DIGE gels comparing PTC and matched normal thyroid tissue protein indicated that 25% of the protein spots were differentially expressed at a 2.5-fold cutoff and 35% at two-fold. Comparison between two different pools of protein from normal thyroid tissues revealed differential protein expression of only 4% at 2.5-fold and 6% at two-fold cutoff. One hundred ninety-two protein spots were identified by MALDI-TOFMS, representing 90 distinct proteins. Excluding albumin, globins and thyroglobulin, imaging software determined 31 proteins to be differentially expressed at the two-fold (or greater) level. Individual gel comparisons (PTC vs. matched normal) from five patients established that 15/31 (48%) of these proteins exhibited statistically significant differential expression. Previously identified molecular markers in this group of proteins include cathepsin B, cytokeratin 19, and galectin-3. Novel differentially expressed proteins include S100A6, moesin, HSP70 (BiP), peroxiredoxin 2, protein phosphatase 2, selenium binding protein 1, vitamin D binding protein, and proteins involved in mitochondrial function. The use of two-dimensional gel electrophoresis (2DGE) revealed a significantly altered protein mass and/or pI in 10%-15% of proteins, suggesting alternatively spliced forms and other posttranslational modification of proteins revealed by this approach. We confirmed S100A6 as a potentially useful biomarker using immunohistochemical analysis (85% sensitivity and 69% specificity for distinguishing benign from malignant thyroid neoplasms). In summary, proteomic analysis of PTC using DIGE and mass spectrometry has confirmed several known biomarkers, uncovered novel potential biomarkers, and provided insights into global pathophysiologic changes in PTC. Many of the differences observed would not have been detected by genomic or other proteomic approaches.

A limited set of human MicroRNA is deregulated in follicular thyroid carcinoma

CONTEXT

Although the pathogenesis of follicular thyroid carcinoma (FTC) and its relation to follicular adenoma (FA) remains unclear, detailed understanding of FTC carcinogenesis would facilitate addressing the scientific and clinical challenges, given that there are morphological and molecular similarities between FTC and the frequently occurring FA. Micro-RNAs (miRNAs) are a new class of small, noncoding RNAs implicated in development and cancer and may lend novel clues to FTC genesis. For the latter process, a deregulated miRNA can orchestrate the aberrant expression of several hundred target genes.

OBJECTIVE

The objective of the study was to identify deregulated miRNAs in FTC.

DESIGN

We used two high-density expression arrays to identify miRNAs and their target genes that are differentially expressed between FTC and FA. Validation was done by quantitative RT-PCR. We further functionally characterized the effect of deregulated miRNAs in vitro using HEK293T, FTC133, and K5 cell lines.

PATIENTS

In total, 45 primary thyroid samples (23 FTC, 20 FA, four normal control thyroid) were analyzed.

RESULTS

Two specific miRNAs, miR-197 and miR-346, were significantly overexpressed in FTC. In vitro overexpression of either miRNA induced proliferation, whereas inhibition led to growth arrest. Overexpression of miR-197 and miR-346 repressed the expression of their predicted target genes in vitro and in vivo.

CONCLUSIONS

Our observations show that miR-197 and miR-346 contribute to FTC carcinogenesis. Both miRNAs and their target genes might potentially provide for novel molecular markers and act as novel targets for treatment by interference, which could potentially normalize the deregulated profile of many downstream target genes.

Follicular thyroid carcinoma: From diagnosis to treatment

Unusual presentations with bone, lung or soft tissue metastases in initial diagnosis of follicular thyroid carcinoma have been reported occasionally. This implies how difficult it is to diagnosis this type of cancer at the pre-operative or intra-operative stage of treatment. Fine needle aspiration cytology has been shown to be an ineffective method for diagnosing vascular or capsule invasion of follicular thyroid cancer. Multiple frozen sections, usually 5 to 12 depending on the size of the tumor, can achieve a diagnostic accuracy of 98%. Clinical application of various gene expressions in thyroid follicular tumors by needle aspiration using in situ hybridization requires further investigation. Although radioactive iodide (131I) has been used as the standard treatment for follicular thyroid carcinoma with distant metastases, the effectiveness of 131I treatment for follicular thyroid carcinoma depends on the differentiation of cancer cells. The possibility of 131I for thyroid remnant ablation replacing a secondary operation for follicular thyroid carcinoma has been debated. Recent studies applied more expressions of sodium iodide symporters to attain the effect of 131I treatment and slow the proliferation of thyroid cancer cell which, in turn, slows the progression of follicular carcinoma. Consensus for the surgical procedures for the specific prognostic risks for follicular thyroid carcinoma is needed. Dedifferentiated, anti-angiogenic, or gene therapies for follicular thyroid cancer with distant metastases or anaplastic transformation comprise the principal directions in future research for this cancer.

Promising molecular techniques for discriminating among follicular thyroid neoplasms

To guide the extent of thyroidectomy for indeterminate follicular neoplasm (FN), clinicians have long sought ways to differentiate follicular adenoma from carcinoma pre- or intraoperatively. Several promising molecular techniques have recently appeared including loss of heterozygosity analysis and molecular profiling microarray analysis. These new tools may also prove useful in determining prognosis, thus and allow a paradigm change in current management of the thyroid nodule.

Identification of candidates for tumor-specific alternative splicing in the thyroid

Alternative splicing is the differential processing of exon junctions to produce a new transcript variant from one gene. Some aberrant splicing, however, has been shown to be cancer specific. Identification of these specific splice variations will provide important insight into the molecular mechanism of normal cellular physiology as well as the disease processes. To gain knowledge about whether alternative splicing is linked to thyroid tumorigenesis, we used our prediction database to select targets for analysis. Fifteen putatively new alternative splicing isoforms were selected on the basis of their expression in thyroid libraries and/or their origin in genes previously associated with carcinogenesis. Using a set of 66 normal, benign, and malignant thyroid tissue samples, new splicing events were confirmed by RT-PCR for 13 of 15 genes (a validation rate of 87%). In addition, new alternative splicing isoforms not predicted by the system and not previously described in public databases were identified. Five genes (PTPN18, ABI3BP, PFDN5, SULF2, and ST5) presented new and/or additional unpredicted isoforms differentially expressed between malignant and benign or normal thyroid tissues, confirmed by sequencing. PTPN18, ABI3BP, and PFDN5 revealed a statistically significant differential splicing profile. In addition, real-time PCR analysis revealed that expression of an alternative PFDN5 variant was higher in malignant lesions than in benign lesions or normal tissues.

Kruppel-like factor 2 (KLF2) regulates proinflammatory activation of monocytes

The mechanisms regulating activation of monocytes remain incompletely understood. Herein we provide evidence that Kruppel-like factor 2 (KLF2) inhibits proinflammatory activation of monocytes. In vitro, KLF2 expression in monocytes is reduced by cytokine activation or differentiation. Consistent with this observation, KLF2 expression in circulating monocytes is reduced in patients with chronic inflammatory conditions such as coronary artery disease. Adenoviral overexpression of KLF2 inhibits the LPS-mediated induction of proinflammatory factors, cytokines, and chemokines and reduces phagocytosis. Conversely, short interfering RNA-mediated reduction in KLF2 increased inflammatory gene expression. Reconstitution of immunodeficient mice with KLF2-overexpressing monocytes significantly reduced carrageenan-induced acute paw edema formation. Mechanistically, KLF2 inhibits the transcriptional activity of both NF-kappaB and activator protein 1, in part by means of recruitment of transcriptional coactivator p300/CBP-associated factor. These observations identify KLF2 as a novel negative regulator of monocytic activation.

Atherosclerotic plaque macrophage transcriptional regulators are expressed in blood and modulated by tristetraprolin

Circulating monocytes and plaque macrophages mediate inflammation in the pathogenesis of atherosclerosis. We purified these cells from patients undergoing carotid endarterectomy for advanced atherosclerosis and examined their in vivo transcriptomes using the serial analysis of gene expression (SAGE) technique. We observed striking differences in transcriptional regulators as monocytes transformed into plaque macrophages in contrast to monocytes and lung macrophages from normal subjects. Consistent with its role in moderating inflammation, tristetraprolin (TTP, ZFP36) was among the most highly expressed macrophage transcriptional regulators. Interestingly, the mRNAs of a subset of the macrophage transcriptional regulators specifically interacted with TTP, revealing a network of genes that may be important in controlling macrophage inflammatory activity. Giving functional significance to this interaction, the knockdown of TTP increased both cognate macrophage gene mRNAs and inflammatory tumor necrosis factor protein release. In contrast, transient overexpression of TTP resulted in decreased levels of the same genes supporting its role in regulating macrophage gene expression. Together, our results indicate that the in vivo gene expression analyses of cells involved in pathogenesis can provide biological insights for functional studies with potential clinical implications.

Pathogenetic mechanisms in thyroid follicular-cell neoplasia

Thyroid cancer is one of the few malignancies that are increasing in incidence. Recent advances have improved our understanding of its pathogenesis; these include the identification of genetic alterations that activate a common effector pathway involving the RET-Ras-BRAF signalling cascade, and other unique chromosomal rearrangements. Some of these have been associated with radiation exposure as a pathogenetic mechanism. Defects in transcriptional and post-transcriptional regulation of adhesion molecules and cell-cycle control elements seem to affect tumour progression. This information can provide powerful ancillary diagnostic tools and can also be used to identify new therapeutic targets.

How to define follicular thyroid carcinoma?

The appropriate diagnosis of follicular thyroid carcinoma (FTC) still depends on its histological discrimination from follicular adenoma (including the distinction of benign from malignant oncocytic variants), papillary thyroid carcinoma (particularly from the follicular variants) and poorly differentiated thyroid carcinoma. The use of immunohistochemical markers contributed only marginally to better defining FTC. The introduction of the micro array technique, however, may offer the possibility of getting a better insight into the natural history, as well as predicting the clinical course, of a given thyroid nodule. This review attempts to recapitulate common standards in the diagnosis of FTC, to summarise current molecular data available to distinguish FTC from other benign and malignant tumours and, finally, to outline future perspectives to define FTC on its specific genetic features.

A six-gene model for differentiating benign from malignant thyroid tumors on the basis of gene expression

BACKGROUND

Thyroid nodules are common; fine-needle aspirations commonly are read as indeterminate, necessitating surgery to exclude carcinoma. We developed a 6-gene array-based predictor model to diagnose benign versus malignant thyroid lesions. In this study, we verified whether quantitative reverse transcription-polymerase chain reaction (qRT-PCR) using this model reliably can differentiate benign from malignant thyroid nodules.

METHODS

Molecular profiles of benign (follicular adenomas, hyperplastic nodules) and malignant tumors (papillary thyroid carcinomas, follicular variants of papillary thyroid carcinomas) were analyzed using qRT-PCR from our 6-gene model (kit, Hs.296031, Hs.24183, LSM7, SYNGR2, C21orf4). The gold standard was standard pathologic criteria. A diagnosis-predictor model was built by using the training samples and was then used to predict the class of 10 additional samples analyzed as unknowns.

RESULTS

Our predictor model using 47 training samples correctly predicted 9/10 unknowns. One sample diagnosed as benign by standard histologic criteria was diagnosed as malignant by our model (sensitivity 75%; specificity, 100%; positive predictive value, 100%; negative predictive value, 85.7%).

CONCLUSIONS

Molecular diagnosis with our 6-gene model can differentiate between benign and malignant thyroid tumors with high sensitivity and specificity. In combination, these genetic markers may be a reliable test to preoperatively diagnose the malignant potential of thyroid nodules.

New prognostic scales LAST-1 and LAST-2: supporting prediction and staging of thyroid cancer

INTRODUCTION

Epidemiologically, thyroid gland tumors are lesions of the highest importance among endocrine tumors in humans. Although the results of surgical treatment of the highly differentiated (follicular and papillary) tumors seem to be satisfactory, treatment of the poorly differentiated (medullary and anaplastic) tumor still demands clinical and basic investigations. In this study the authors sought to evaluate clinical and molecular factors that could contribute to preoperative detection of more advanced thyroid cancers (i.e., those that exhibit extrathyroid spread and lymph node invasion).

METHODS

A total of 27 patients operated on for thyroid cancer were evaluated according to age, sex, time from the onset of the disease, cytogenetic changes, and loss of heterozygosity (LOH) in 14 microsatellite markers. The output variables were defined according to postoperative findings and the TNM 2002 score. The T1-2 N0 M0 cases were defined as local malignancy (LM); and T3-4 any N any M, any T N1 any M, or any T any N M1 were considered advanced malignancy (AM). The control groups consisted of 25 patients with multinodular goiter (MNG) and 32 patients with follicular adenoma (FA). In all cases, clinical and molecular data similar to those listed above were collected, excluding staging and follow-up information.

RESULTS

There was no predominant specific type of chromosomal aberration observed and no marker lost in more than five patients (18%). The logistic regression identified three input variables as contributing significantly to the dichotomized outcome measure (LM vs. AM): LOH in any of the examined loci, age of the patient at the presentation, and the sex of the patient. Furthermore, discriminant analysis revealed four input variables differentiating among TC, FA, and MNG patients. Based on the multivariate analysis results, two numeric prognostic scales were fashioned: LAST-1, a scale applicable to differentiation of thyroid cancers at different degrees of clinical advancement; and LAST-2, a scale applicable to differentiation of any thyroid lumps.

CONCLUSIONS

It was concluded that LOH and the age and sex of the patients can provide sufficient data to predict thyroid cancer with a high degree of clinical advancement. LAST-1 scale is a reliable tool for identifying these patients. The LAST-2 scale gives supportive information about the character of thyroid lumps, distinguishing TC from MNG and FA.

Diagnostic criteria in well-differentiated thyroid carcinomas

The criteria used for the differential diagnosis of well-differentiated thyroid tumors derived from follicular cells are reviewed taking into account the architectural characteristics together with the immunohistochemical and molecular features. The review is focused on follicular carcinoma, papillary carcinoma, follicular variant of papillary carcinoma, and oncocytic (Hürthle cell) tumors, as well as on the recently described borderline lesions: follicular and well-differentiated tumors of uncertain malignant potential, and well-differentiated carcinoma, not otherwise specified.

Class distinction between follicular adenomas and follicular carcinomas of the thyroid gland on the basis of their signature expression

BACKGROUND

Nodules of the thyroid gland are observed frequently in patients who undergo ultrasound studies. The majority of these nodules are benign, corresponding to goiters or adenomas, and only a small fraction corresponds to carcinomas. Among thyroid tumors, the diagnosis of follicular adenocarcinomas by preoperative fine-needle aspiration biopsy is a major challenge, because it requires inspection of the entire capsule to differentiate it from adenoma. Consequently, large numbers of patients undergo unnecessary thyroidectomy.

METHODS

Using data from gene expression analysis, the authors applied Fisher linear discriminant analysis and searched for expression signatures of individual samples of adenomas and follicular carcinomas that could be used as molecular classifiers for the precise classification of malignant and nonmalignant lesions.

RESULTS

Fourteen trios of genes were described that fulfilled the criteria for the correct classification of 100% of samples. The robustness of these trios was verified by using leave-1-out cross-validation and bootstrap analyses. The results demonstrated that, by combining trios, better classifiers could be generated that correctly classified >92% of samples.

CONCLUSIONS

The strategy of classifiers based on individual signatures was a useful strategy for distinguishing between samples with very similar expression profiles.

Immunohistochemical separation of follicular variant of papillary thyroid carcinoma from follicular adenoma

The accurate diagnosis of differentiated thyroid tumors is very important for clinical management of patients. The histopathological distinction between some types of differentiated thyroid tumors can be very difficult even for experienced pathologists. We used immunohistochemical markers from published data obtained from DNA expression profiling, tissue microarray analysis, and immunohistochemistry to analyze a series of 157 thyroid tumors and 5 normal thyroids. These analyses showed that several antibodies were useful in distinguishing follicular adenomas from follicular variant of papillary thyroid carcinomas including HBME-1, CITED1, galectin-3, cytokeratin 19, and S100A4 (p < 0.0001). A combination of markers consisting of a panel of HBME-1, galectin-3, and CK19 or a panel of HBME-1, CITED1, and galectin-3 was usually most effective in distinguishing follicular adenoma from follicular variant of papillary thyroid carcinoma. Because individual tumors may not express some of these markers, the use of a panel of antibodies is recommended. These results indicate that some individual antibodies or a panel of antibodies combined with histopathological analysis can be useful in separating follicular adenoma (FA) from follicular variant of papillary thyroid carcinoma (FVPTC).

Differentiation of Follicular Thyroid Adenoma from Carcinoma by Means of Gene Expression Profiling with Adapter-Tagged Competitive Polymerase Chain Reaction

OBJECTIVE

Since preoperative differentiation between follicular thyroid adenoma (FTA) and carcinoma (FTC) remains very difficult, the purpose of this study was to identify the genes differentially expressed in FTA and FTC in order to construct a diagnostic system based on such genes for differentiation of FTA and FTC.

METHODS

Gene expression profiles of 45 FTAs and 22 FTCs were analyzed by means of adapter-tagged competitive polymerase chain reaction (ATAC-PCR) with 2,516 genes (learning set). The genes differentially expressed in FTAs and FTCs were then used to construct a diagnostic system based on the weighted-voting algorithm. In addition, a validation study of this diagnostic system was conducted using 12 FTAs and 6 FTCs (validation set).

RESULTS

The diagnostic system for differentiation of FTA and FTC, constructed with the aid of the learning set samples, was based on 60 genes differentially expressed in FTA and FTC, which included several genes previously identified as overexpressed in FTC (DPP4, KRT19 and IGFBP3) or FTA (trefoil factor 3 and thyroid peroxidase). The leave-one-out cross-validation study showed that the accuracy of this diagnostic system was as high as 90% (sensitivity: 77.3% and specificity: 95.6%), and was confirmed by the validation study (diagnostic accuracy: 83.3%; 95% confidence interval: 62.8-95.4%, sensitivity: 66.7% and specificity: 91.2%).

CONCLUSIONS

This diagnostic system using the ATAC-PCR assay is expected to be clinically useful for preoperative differentiation between FTA and FTC since ATAC-PCR can be used for the small amount of RNA obtained from fine needle aspiration biopsy.

Cancer-associated loss of TARSH gene expression in human primary lung cancer

PURPOSE

We have previously identified mouse Tarsh as one of the cellular senescence-related genes and showed the loss of expression of TARSH mRNA in four human lung cancer cell lines. TARSH is a presumptive signal transduction molecule interacting with NESH, which is implicated to have some roles in lung cancer metastasis.

METHODS

The amplification of complete ORF-encoding TARSH cDNA was done with reverse transcription-PCR. Northern blotting was carried out using TARSH cDNA probes. To clarify the relationship between TARSH and lung cancer, we quantified TARSH mRNA expression in 15 human lung cancer cell lines and 32 primary non-small cell lung cancers.

RESULTS

We first determined the complete ORF-encoding cDNA sequence which is expressed in the human lung. On the Northern hybridization analysis, TARSH was strongly expressed in the human lung. The expression of TARSH mRNA is remarkably downregulated in all the lung cancer cell lines examined. Furthermore, TARSH expression was significantly low in all of the tumor specimens when compared to the expression in corresponding non-neoplastic lung tissue specimens.

CONCLUSION

The cancer-associated transcriptional inactivation of TARSH suggests that TARSH could be used as a biomarker for lung cancer development as well as a molecular adjunct for lung carcinogenesis in human.

Pathogenesis of differentiated thyroid cancer (papillary and follicular)

Differentiated thyroid cancers (papillary - PTC and follicular - FTC) are the most common endocrine malignancies. The recent progresses in the understanding of PTC and FTC pathogenesis are summarized in this review. In PTC, a single mutation of BRAF (the gene for the B-type Raf kinase) (V600E) is responsible for the disease in 40-50% of patients, especially in older people and is associated with a poorer clinicopathological outcome. Due to these characteristics, its use as a specific diagnostic and prognostic marker for PTC in cytological specimens is being implemented. Another important cause of PTC is rearrangements of the RET tyrosine kinase receptor (RET/PTC), which represent a recombination of the promoter and N-terminal domain of a partner gene with the C-terminal region of the RET gene, resulting in a chimeric gene with a protein product containing a constitutively activated RET tyrosine kinase, responsible for 20-30% patients, specially the younger or after radiation. The pathogenesis of FTC is less understood. A chromosomal translocation between the transcription factor PAX8 and the peroxisome proliferator-activated receptorgamma (PPARgamma) occurs in 30-50% of patients; however, the presence of PAX8-PPARgamma is also demonstrated in follicular adenomas. Therefore, there is no complete evidence that PAX8-PPARgamma is the cause of FTC. Another finding in FTC is mutations on the RAS gene, which excludes PAX8-PPARgamma rearrangements. Several genes, as TRgamma, PTEN, PKAR1A, DDIT3, ARG2, ITM1 and C1orf24 - some discovered by techniques of differential gene expression -, have been recently implicated in the pathogenesis of FTC.

Étude du contenu en ADN nucléaire dans les nodules thyroïdiens

Thyroid nodules are frequent and sometimes they pose a diagnostic and prognostic problem. DNA ploidy study and cell cycle analysis could be of value in the distinction between benign tumors and malignant tumors. Formalin-fixed and paraffin-embedded tissues from 69 patients with different benign and neoplastic lesions were investigated. Nuclear DNA content in thyroid cells was measured after Feulgen staining using SAMBA 200 image analysis system. A diploid DNA stemline was revealed in 75% of histologically proven benign thyroid tumors (15/20) and aneuploidy was found in 57.2% of malignant tumors (28/49). There is a significant correlation between aneuploidy and extra-thyroid extension (p=0.007) and bilateral and/or mediastinal lymph node metastasis (p=0.02). In the majority of benign tumors (19/20), the proliferation index was lower than 3% (< or =3%) however, this index value was higher than 3% (>3%) in more than 83% of malignant tumors (41/49) (p<0.001). The S phase fraction analysis revealed that the threshold of 14% divide the near whole of benign and malignant tumors (p<0.001). Our findings show that in follicular lesions, proliferation index and S phase fraction study appears interesting and helpful in the distinction between benign and malignant tumors, and aneuploidy seems more interesting in prognosis evaluation of these tumors.

Follicular thyroid tumors with the PAX8-PPARgamma1 rearrangement display characteristic genetic alterations

Follicular thyroid carcinomas (FTC) arise through oncogenic pathways distinct from those involved in the papillary histotype. Recently, a t(2;3)(q13;p25) rearrangement, which juxtaposes the thyroid transcription factor PAX8 to the peroxisome proliferator-activated receptor (PPAR) gamma1, was described in FTCs. In this report, we describe gene expression in 11 normal tissues, 4 adenomas, and 8 FTCs, with or without the PAX8-PPARgamma1 translocation, using custom 60-mer oligonucleotide microarrays. Results were confirmed by quantitative real-time polymerase chain reaction of 65 thyroid tissues and by immunohistochemistry. Statistical analysis revealed a pattern of 93 genes discriminating FTCs, with or without the translocation, that were morphologically undistinguishable. Although the expression of thyroid-specific genes was detectable, none appeared to be differentially regulated between tumors with or without the translocation. Differentially expressed genes included genes related to lipid/glucose/amino acid metabolism, tumorigenesis, and angiogenesis. Surprisingly, several PPARgamma target genes were up-regulated in PAX8-PPARgamma-positive FTCs such as angiopoietin-like 4 and aquaporin 7. Moreover many genes involved in PAX8-PPARgamma expression profile presented a putative PPARgamma-promoter site, compatible with a direct activity of the fusion product. These data identify several differentially expressed genes, such as FGD3, that may serve as potential targets of PPARgamma and as members of novel molecular pathways involved in the development of thyroid carcinomas.

The prognostic value of primary tumor size in papillary and follicular thyroid carcinoma

BACKGROUND

A delay in the diagnosis of differentiated thyroid carcinoma often leads to larger tumors, higher prevalence rates of distant metastasis, and earlier cause-specific deaths. Threshold tumor diameters for extrathyroidal growth, lymph node spread, and distant metastasis in papillary (PTC) and follicular thyroid carcinoma (FTC) remain to be defined.

METHODS

A comparative correlation of primary tumor size and extrathyroidal growth, lymph node spread, and distant metastasis was performed for 500 institutional patients who received surgery for PTC or FTC.

RESULTS

There were 366 patients with PTC (73.2%) and 134 patients with FTC (26.8%). Multifocality (23.5% vs. 9.0%; P < 0.001) and lymph node metastasis (40.2% vs. 19.4%; P < 0.001) were more common in the patients with PTC than in those with FTC. Patients with FTC were older at first diagnosis (51.6 vs. 47.0 years; P = 0.01) compared with the patients with PTC. The FTC tumors were almost twice as large (39.9 vs. 20.6 mm; P < 0.001), and patients had a higher prevalence of distant metastasis (17.9% vs. 6.3%; P < 0.001). When primary tumor diameter was accounted for, cumulative risks of extrathyroidal growth and lymph node metastasis were higher in patients with PTC than in patients with FTC (P < 0.001; log-rank test). In striking contrast, the cumulative risk of distant metastasis was the same for PTC and FTC tumors of equal size (P = 0.89; log-rank test) and increased once the primary tumor size was > 20 mm. Pulmonary metastasis was an earlier event than bone metastasis.

CONCLUSIONS

The data suggested that earlier intervention is warranted to keep suspicious thyroid nodules from growing > 20 mm (or greater than T1) and spreading to distant organs.

Expression of TARSH gene in MEFs senescence and its potential implication in human lung cancer

To reveal the molecular mechanism of cellular senescence, we have surveyed the genes that are specifically upregulated via MEFs senescence by suppression subtractive hybridization method. We show here that mTARSH was induced particularly in the relative early phase of MEFs cellular senescence. Further structural analysis of mTARSH disclosed five splicing variants shared a common reading frame whose diversity was derived from the SH3-binding motif cluster in the middle of the gene. We also show that mTARSH mRNA predominantly expressed in lung and that conspicuous expression of TARSH was drastically declined in all several lung cancer cell lines we tested. Thus, TARSH presumably represents a trigger gene for evoking cellular senescence, which has also been suggested to be involved in the prevention of tumorigenesis.

Targeted disruption of p53 attenuates doxorubicin-induced cardiac toxicity in mice

Use of the chemotherapeutic agent doxorubicin (Dox) is limited by dose-dependent cardiotoxic effects. The molecular mechanism underlying these toxicities are incompletely understood, but previous results have demonstrated that Dox induces p53 expression. Because p53 is an important regulator of the cell birth and death we hypothesized that targeted disruption of the p53 gene would attenuate Dox-induced cardiotoxicity. To test this, female 6-8 wk old C57BL wild-type (WT) or p53 knockout (p53 KO) mice were randomized to either saline or Dox 20 mg/kg via intraperitoneal injection. Animals were serially imaged with high-frequency (14 MHz) two-dimensional echocardiography. Measurements of left ventricle (LV) systolic function as assessed by fractional shortening (FS) demonstrated a decline in WT mice as early as 4 days after Dox injection and by 2 wk demonstrated a reduction of 31 +/- 16% (P < 0.05) from the baseline. In contrast, in p53 KO mice, LV FS was unchanged over the 2 wk period following Dox injection. Apoptosis of cardiac myocytes as measured by the TUNEL and ligase reactions were significantly increased at 24 h after Dox treatment in WT mice but not in p53 KO mice. After Dox injection, levels of myocardial glutathione and Cu/Zn superoxide dismutase were preserved in p53 KO mice, but not in WT animals. These observations suggest that p53 mediated signals are likely to play a significant role in Dox-induced cardiac toxicity and that they may modulate Dox-induced oxidative stress.

Follicular thyroid lesions, elements that affect both diagnosis and prognosis

The precise diagnosis of follicular thyroid lesions is frequently debated because of the subjective nature of capsular invasion as well as both the histological and cytological characteristics. Furthermore, several different prognostic indices have been devised to examine prognosis associated with thyroid cancer. Herein, we describe how these confounding elements can affect the ability to accurately predict prognosis for patients with follicular thyroid lesions.

Circulating transcriptome reveals markers of atherosclerosis

Circulating monocytes mediate inflammation in atherosclerosis and may serve as easily accessible reporters of disease. To search for markers of atherosclerosis, we compared the in vivo transcriptomes of monocytes purified from patients undergoing carotid endarterectomy and normal subjects by using the serial analysis of gene expression technique. We selected a subset of differentially expressed monocyte-specific genes and confirmed their expression levels. The Finkel-Biskis-Jinkins osteosarcoma (FOS) gene was significantly increased in patients, and the highest levels of FOS associated with patients who had previously undergone coronary revascularization. The correlation between coronary revascularization and FOS was higher than that compared with the cardiac risk marker high sensitivity C-reactive protein. In vitro inhibition of FOS using small interfering RNA and 3-hydroxy-3-methyl-glutaryl CoA reductase inhibitor simvastatin (statin) affected monocyte activation and suggested an important role in pathogenesis. Given the prominent role of FOS in inflammation and calcification, its association with atherosclerosis severity has clear pathophysiologic bases as well as clinical implications as a marker. Our results suggest that analysis of gene expression in circulating cells may provide biological and clinical insights into human atherosclerosis, and that this type of approach may be applicable for studying other types of diseases.