CITED1 protein expression suggests Papillary Thyroid Carcinoma in high throughput tissue microarray-based study

Immunohistochemical Study Protocol in Thyroid Pathology

Immunohistochemical study proves valuable in the diagnosis of neoplastic pathology. Its application allows us to differentiate the origin of tumors, as seen with thyroglobulin and TTF1 in well-differentiated tumors of follicular origin and calcitonin or other neuroendocrine markers for tumors arising from C cells. At times, immunohistochemical study becomes necessary for the classification of thyroid carcinomas arising from follicular cells, although specific antibodies that would enable the exclusion of malignancy or differentiation between follicular carcinomas and papillary carcinomas have generally not been found; hence, various antibody panels are utilized. HMBE1 and galectin 3 can be beneficial in distinguishing malignancy from benignity, while CK19, galectin 3, and HMBE1 aid in identifying papillary carcinomas of follicular variant. In the differential diagnosis depending on histological morphology, various panels with automated protocols prove greatly useful.

Roles and signaling pathways of CITED1 in tumors: overview and novel insights

CBP/p300 interacting transactivator with Glu/Asp-rich carboxy-terminal domain 1 (CITED1) is a transcriptional activator belonging to the non-DNA-binding transcription co-regulator family. It regulates diverse pathways, including the transforming growth factor/bone morphogenetic protein/SMAD, estrogen, Wnt-β-catenin, and androgen-AR signaling pathways, by binding to CBP/p300 co-activators through its conserved transactivation domain CR2. CITED1 plays an important role in embryonic development and a certain regulatory role in the occurrence and development of various tumors. In this article, the biological characteristics, expression regulation, participating signaling pathways, and potential roles of CITED1 in the clinical diagnosis and treatment of tumors are reviewed.

Preparation and SPECT/CT Imaging of 177Lu-Labeled Peptide Nucleic Acid (PNA) Targeting CITED1: Therapeutic Evaluation in Tumor-Bearing Nude Mice

Purpose

The expression of Cbp/p300-interacting transactivator with Glu/Asp-rich carboxy-terminal domain 1 (CITED1) is upregulated in papillary thyroid carcinoma (PTC) and mediates cell proliferation and migration. To facilitate early diagnosis and monitoring of recurrent or metastatic PTC, we designed ¹⁷⁷Lu-labeled antisense peptide nucleic acid (PNA) targeting CITED1 mRNA to evaluate the therapeutic potential, while analyzing its distribution in nude mice and the characteristics withsingle-photon emission-computed tomography/computed tomography (SPECT/CT) imaging.

Materials and Methods

¹⁷⁷Lu-DOTA-anti-CITED1-PNA (¹⁷⁷Lu-asPNA) was obtained by indirect labeling. High-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) were used to determine the labeling rate and radiochemical purity. The stability of ¹⁷⁷Lu-asPNA was evaluated by TLC, and the radioactivity count was measured by a γ counter to calculate its uptake capacity in K1 cells. To analyze the distribution of ¹⁷⁷Lu-asPNA in body tissues and organs of nude mice, static single-photon emission-computed tomography (SPECT) imaging and SPECT/CT image fusion were performed. Then, the therapeutic effects of probes were explored by tumor growth curves and survival analysis.

Results

Our probe showed a radiochemical purity of 96.5±0.15% at 1 hr and specific activity of 8.7±0.53 MBq/μg. The uptake rate in the ¹⁷⁷Lu-asPNA group was much higher than that in the ¹⁷⁷Lu-DOTA-nonsense-PNA (¹⁷⁷Lu-nonsense-PNA) and ¹⁷⁷Lu-DOTA groups (P<0.05). The biological distribution showed that the tumor/muscle ratio was at its highest at 24 h (4.98±0.34) post-inoculation, with SPECT/CT imaging showing clear tumor development. By measuring tumor volume of tumor-bearing nude mice, the ¹⁷⁷Lu-asPNA group showed a significant difference in tumor size 9 days after injection (P < 0.05). Kaplan-Meier survival curves showed that the overall survival rate in the ¹⁷⁷Lu-asPNA group was significantly different from those in the DOTA-anti-CITED1-PNA (asPNA) and saline groups (P = 0.002, log-rank test).

Conclusion

¹⁷⁷Lu-asPNA was developed successfully, showing a high labeling rate and good stability. SPECT/CT imaging demonstrated tumor growth in nude mice, which was effectively inhibited by our probe, thus prolonging survival.

Microarray-based differential expression profiling of long noncoding RNAs and messenger RNAs in formalin-fixed paraffin-embedded human papillary thyroid carcinoma samples

BACKGROUND

Long noncoding RNAs (lncRNAs) can regulate the expression of genes at almost every level. The altered expression of lncRNAs was observed in many kinds of cancers. Until recently, few studies have focused on the function of lncRNAs in the context of papillary thyroid carcinoma (PTC).

METHODS

In the current study, we collected seven PTC and nodular goiter tissue samples and explored mRNA and lncRNA expression patterns in these samples by microarray.

RESULTS

We observed aberrant expression of 94 lncRNAs and 99 mRNAs in the seven PTC samples as compared to the nodular goiter tissue [fold change (FC) ≥2.0; P<0.01]. To confirm these microarray results, quantitative polymerase chain reaction (q-PCR) was performed to assess the expression of three randomly selected differentially expressed mRNAs and lncRNAs, confirming our microarray findings significantly. We then performed gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) analyses to systematically characterize the twelve significantly differential genes. A co-expression analysis revealed that the lncRNAs n382996, n342483, and n409114 were closely related to the regulation of MT1G, MT1H, and MT1F.

CONCLUSIONS

In the present study a string of novel lncRNAs associated with PTC were identified. Further study of these lncRNAs should be performed to identify novel target molecules which may improve diagnosis and treatment of PTC.

CITED1 promotes proliferation of papillary thyroid cancer cells via the regulation of p21 and p27

Background

It has been reported that CBP/p300-Interacting Transactivator with glutamic acid [E]/aspartic acid [D]-rich C-terminal domain 1 (CITED1) is overexpressed in papillary thyroid cancer (PTC). However, the functional significance and underlying mechanisms of CITED1 in PTC are largely unknown.

Methods

The Cancer Genome Atlas dataset and real-time PCR were used to determine the expression of CITED1 in PTC. The role of CITED1 in PTC cell proliferation was determined conducted using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, 5-ethynyl-2'-deoxyuridine (EdU) incorporation, and flow cytometry assays in vitro, and a subcutaneous xenotransplantation tumor model in nude mice was established to analyze tumor growth in vivo. We studied the potential mechanisms underlying the contribution of CITED1 to PTC proliferation using western blotting and luciferase assays.

Results

We found that CITED1 was highly expressed in PTC. In vitro and in vivo experiments demonstrated that CITED1 was involved in PTC cell proliferation and tumorigenesis. Then, gain- and loss-of-function experiments revealed that CITED1 decreased the expression of p21 and p27, and thereby increased the phosphorylation of pRb as well as E2F1 transcriptional activity.

Conclusions

Our results suggest that CITED1 is overexpressed in PTC and that CITED1 promotes the proliferation of PTC cells via the regulation of p21 and p27, which indicates that CITED1 might be a potential therapeutic target in the treatment of PTC.

The epigenetic landscape of differentiated thyroid cancer

Differentiated thyroid carcinoma of follicular cell-derivation is the most common endocrine neoplasm with a rapidly increasing incidence. The majority represent papillary carcinomas; more rarely, they are follicular carcinomas. The vast majority have indolent behavior, however a significant proportion progress to develop lymph node metastases and a smaller proportion disseminate systemically. While common and frequent genetic events have been described to underlie the development of these neoplasms, the factors contributing to differing behaviors among tumors with similar genetic alterations remain unclear. This review focuses on epigenetic mechanisms targeting major signaling pathways that underlie the spectrum of biological behaviors and that may have potential diagnostic, prognostic and therapeutic value.

Immunohistochemical Biomarkers in Thyroid Pathology

The application of immunohistochemistry to the diagnosis of thyroid lesions has increased as new biomarkers have emerged. In this review, we discuss the biomarkers that are critical for accurate diagnosis, prognosis, and management. Immunohistochemical markers are used to confirm that an unusual tumor in the thyroid is indeed of thyroid origin, either of follicular epithelial or C-cell differentiation; the various mimics include nonthyroidal lesions such as parathyroid tumors, paragangliomas, thymic neoplasms, and metastatic malignancies. Tumors of thyroid follicular epithelial cells can be further subclassified using a number of immunohistochemical biomarkers that can distinguish follicular-derived from C-cell lesions and others that support malignancy in borderline cases. The use of mutation-specific antibodies can distinguish papillary carcinomas harboring a BRAF^V600E mutation from RAS-like neoplasms. Immunostains have been developed to further identify molecular alterations underlying tumor development, including some rearrangements. Altered expression of several biomarkers that are known to be epigenetically modified in thyroid cancer can be used to assist in predicting more aggressive behavior such as a propensity to develop locoregional lymphatic spread. Immunohistochemistry can assist in identifying lymphatic and vascular invasion. Biomarkers can be applied to determine dedifferentiation and to further classify poorly differentiated and anaplastic carcinomas. The rare tumors associated with genetic predisposition to endocrine neoplasia can also be identified using some immunohistochemical stains. The application of these ancillary tools allows more accurate diagnosis and better understanding of pathogenesis while improving prediction and prognosis for patients with thyroid neoplasms.

CITED1 gene promotes proliferation, migration and invasion in papillary thyroid cancer

Thyroid cancer is the most common malignancy of the endocrine organs. In order to further understand the tumorigenesis and progression of papillary thyroid carcinoma (PTC), the present study performed whole transcriptome sequence analysis. It was found that Cbp/p300-interacting transactivators with glutamic acid [E] and aspartic acid [D]-rich C-terminal domain 1 (CITED1) was a novel potential PTC-associated gene in thyroid cancer. The expression level and clinicopathological features of CITED1 were then assessed in The Cancer Genome Atlas (TCGA) database. The expression of CITED1 was knocked down and the biological function of CITED1 in PTC cell lines was examined. The results showed that upregulated CITED1 was associated with lymph node metastasis (P=0.006) and clinical stage (P=0.003). In order to differentiate PTC tissues and normal tissues, an area under the curve was constructed of a receiver operating characteristic of 91.3% for the TCGA cohort and 85.3% for a validated cohort. The downregulated expression of CITED1 significantly inhibited cell proliferation, colony formation, migration and invasion in the PTC cell lines. The present study demonstrated that CITED1 is important in the tumorigenesis and metastasis of PTC and may be a potential therapeutic target in PTC.

Special role of JUN in papillary thyroid carcinoma based on bioinformatics analysis

Background

Papillary thyroid carcinoma (PTC) is the most common malignancy in thyroid tissue, and the number of patients with PTC has been increasing in recent years. Discovering the mechanism of PTC genesis and progression and finding new potential diagnostic biomarkers/therapeutic target genes of PTC are of great significance.

Methods

In this work, the datasets GSE3467 and GSE3678 were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified with the limma package in R. GO function and KEGG pathway enrichment were conducted with DAVID tool. The interaction network of the DEGs and other genes was performed with Cytoscape plugin BisoGenet, while clustering analysis was performed with Cytoscape plugin ClusterOne.

Results

A total of 1800 overlapped DEGs were detected in two datasets. Enrichment analysis of the DEGs found that the top three enriched GO terms in three ontologies and four significantly enriched KEGG pathways were mainly concerned with intercellular junction and extracellular matrix components. Interaction network analysis found that transcription factor hepatocyte nuclear factor 4, alpha (HNF4A) and DEG JUN had higher connection degrees. Clustering analysis indicated that two function modules, in which JUN was playing a central role, were highly relevant to PTC genesis and progression.

Conclusions

JUN may be used as a specific diagnostic biomarker/therapeutic molecular target of PTC. However, further experiments are still needed to confirm our results.

Digital gene expression profiling of a series of cytologically indeterminate thyroid nodules

BACKGROUND

Fine-needle aspiration cytology (FNAC) has been widely accepted as the most crucial step in the preoperative assessment of thyroid nodules. Testing for the expression of specific genes should improve the accuracy of FNAC diagnosis, especially when it is performed in samples with indeterminate cytology.

METHODS

In total, 69 consecutive FNACs that had both cytologic and histologic diagnoses were collected, and expression levels of 34 genes were determined in RNA extracted from FNAC cells by using a custom digital mRNA counting assay. A supervised k-nearest neighbor (K-nn) learning approach was used to build a 2-class prediction model based on a subset of 27 benign and 26 malignant FNAC samples. Then, the K-nn models were used to classify the 16 indeterminate FNAC samples.

RESULTS

Malignant and benign thyroid nodules had different gene expression profiles. The K-nn approach was able to correctly classify 10 FNAC samples as benign, whereas only 1 sample was grouped in the malignant class. Two malignant FNAC samples were incorrectly classified as benign, and 3 of 16 samples were unclassified.

CONCLUSIONS

Although the current data will require further confirmation in a larger number of cases, the preliminary results indicate that testing for specific gene expression appears to be useful for distinguishing between benign and malignant lesions. The results from this study indicate that, in indeterminate FNAC samples, testing for cancer-specific gene expression signatures, together with mutational analyses, could improve diagnostic accuracy for patients with thyroid nodules.

Microarray technology to investigate genes associated with papillary thyroid carcinoma

DNA microarray data on thyroid tissue from patients with papillary thyroid carcinoma (PTC) and from healthy controls were compared in order to investigate the regulatory genes and uncover the underlying regulatory network in PTC. The DNA microarray data set, GSE3678, was downloaded from Gene Expression Omnibus database. This included seven thyroid tissue samples from patients with PTC and seven samples from healthy controls. Raw data were processed and differentially expressed genes (DEGs) were identified using corresponding R packages. Gene regulation analysis was conducted using TRANSFAC® and TRED. A total of 171 DEGs were obtained. A regulatory network was then established, using 104 of the DEGs. Subsequently, pathway enrichment analyses of the genes were conducted using Database for Annotation, Visualization and Integrated Discovery (DAVID) online tool. Three differentially expressed transcription factors were identified: Trefoil factor 3, cut‑like homeobox 2 and forkhead box protein A2. The most significant pathways involving the 104 DEGs were pathways involved in cancer. Biological process analysis using DAVID, suggested that these genes were associated with the positive regulation of gene expression, gene transcription and metabolic processes. The present study identified a range of genes associated with the development of PTC. The results of the present study were beneficial for understanding the regulatory mechanisms involved in PTC, and for developing clinical diagnostic and therapeutic approaches for this disease.

Molecular diagnostics for thyroid nodules: the current state of affairs

Molecular diagnostics offers great promise for the evaluation of cytologically indeterminate thyroid nodules. Numerous molecular genetic and immunohistochemical tests have been developed that may be performed on thyroid specimens obtained during standard fine-needle aspiration, some of which may greatly improve diagnostic yield. A sound understanding of the diagnostic performance of these tests, and how they can enhance clinical practice, is important. This article reviews the diagnostic utility of immunohistochemical and molecular testing for the clinical assessment of thyroid nodules, and makes recommendations about how these tests can be integrated into clinical practice for patients with cytologically indeterminate thyroid nodules.

Predicting lymph node metastasis in early colorectal cancer using the CITED1 expression

BACKGROUND

The identification of molecular markers that are useful for predicting lymph node metastasis is urgently needed to determine treatment strategies for T1 colorectal cancer (CRC). We previously showed that 10 candidate genes are correlated with de-differentiation at the invasion front of CRC using a gene expression analysis. These 10 genes are potential markers that may predict lymph node metastasis by CRC.

MATERIALS AND METHODS

Samples were obtained from 161 patients with CRC. Quantitative real-time reverse transcription-polymerase chain reaction assays were performed using 66 T3 samples in order to extract genes correlated with lymph node metastasis. Immunohistochemical studies of the extracted genes were performed on 66 T3 and 95 T1 samples. A univariate analysis followed by a multivariate logistic regression model was used to examine independent risk factors for lymph node metastasis.

RESULTS

The CITED1 messenger RNA expression was found to be an independent risk factor for lymph node metastasis in T3 CRC patients (P = 0.040). A high CITED1 protein expression, as detected with immunohistochemistry, was also an independent risk factor in T3 CRC patients (P = 0.035). In T1 colorectal cancer patients, a high CITED1 protein expression was found to be an independent risk factor for lymph node metastasis (P = 0.010). The positive predictive and negative predictive values in the T1 colorectal cancer patients were 27.5% and 95.5%, respectively.

CONCLUSIONS

The CITED1 expression is correlated with lymph node metastasis in patients with CRC. In T1 colorectal cancer patients, CITED1 has the potential ability to predict the presence of lymph node metastasis.

Human BAT possesses molecular signatures that resemble beige/brite cells

Brown adipose tissue (BAT) dissipates chemical energy and generates heat to protect animals from cold and obesity. Rodents possess two types of UCP-1 positive brown adipocytes arising from distinct developmental lineages: “classical” brown adipocytes develop during the prenatal stage whereas “beige” or “brite” cells that reside in white adipose tissue (WAT) develop during the postnatal stage in response to chronic cold or PPARγ agonists. Beige cells’ inducible characteristics make them a promising therapeutic target for obesity treatment, however, the relevance of this cell type in humans remains unknown. In the present study, we determined the gene signatures that were unique to classical brown adipocytes and to beige cells induced by a specific PPARγ agonist rosiglitazone in mice. Subsequently we applied the transcriptional data to humans and examined the molecular signatures of human BAT isolated from multiple adipose depots. To our surprise, nearly all the human BAT abundantly expressed beige cell-selective genes, but the expression of classical brown fat-selective genes were nearly undetectable. Interestingly, expression of known brown fat-selective genes such as PRDM16 was strongly correlated with that of the newly identified beige cell-selective genes, but not with that of classical brown fat-selective genes. Furthermore, histological analyses showed that a new beige cell marker, CITED1, was selectively expressed in the UCP1-positive beige cells as well as in human BAT. These data indicate that human BAT may be primary composed of beige/brite cells.

The biology and the genetics of Hurthle cell tumors of the thyroid

The biology and the genetics of Hürthle cell tumors are reviewed starting from the characterization and differential diagnosis of the numerous benign and malignant, neoplastic and nonneoplastic lesions of the thyroid in which Hürthle cell transformation is frequently observed. The clinicopathologic and molecular evidence obtained from the comparative study of the aforementioned conditions indicate that Hürthle cell appearance represents a phenotype that is superimposed on the genotypic and conventional histopathologic features of the tumors. Hürthle cell tumors differ from their non-Hürthle counterparts regarding the prevalence of large deletions of mitochondrial DNA (mtDNA), mutations of mtDNA genes coding for oxidative phosphorylation (OXPHOS) proteins (namely mutations of complex I subunit genes) and mutations of nuclear genes coding also for mitochondrial OXPHOS proteins. Such mitochondrial alterations lead to energy production defects in Hürthle cell tumors; the increased proliferation of mitochondria may reflect a compensatory mechanism for such defects and is associated with the overexpression of factors involved in mitochondrial biogenesis. The mitochondrial abnormalities are also thought to play a major role in the predisposition for necrosis instead of apoptosis which seems to be blocked in most Hürthle cell tumors. Finally, the results obtained in experimental models using cybrid cell lines and the data obtained from histopathologic and molecular studies of familial Hürthle cell tumors are used, together with the aforementioned genetic and epigenetic alterations, to progress in the understanding of the mechanisms through which mitochondrial abnormalities may be involved in the different steps of thyroid carcinogenesis, from tumor initiation to metastization.

Comparative evaluation of high-throughput small-core (0.6-mm) and large-core (2-mm) thyroid tissue microarray: is larger better?

CONTEXT

Tissue microarrays (TMAs) are useful in gene/protein expression profiling of large number of tumors. Several studies have validated that a 0.6-mm core of a large tumor would give results similar to results of the whole section. However, cores from colloid-filled thyroid follicles, for example in breast carcinoma, may contain fewer cells compared to solid tumors.

OBJECTIVE

The aim of this study is to validate thyroid TMAs choosing 2 core diameters, 0.6 and 2 mm, and to study the effect of core size and grid density on concordance with whole sections.

DESIGN

0.6-mm tissue cores were arrayed on a high-density TMA (406 cores). Two low-density TMAs (35 cores each) composed of 2-mm cores were also constructed. Immunohistochemistry was performed using primary antibodies to cytokeratin 19, HBME1, and CITED1 that have been found to be useful in the diagnosis of thyroid carcinoma. The results were compared with whole sections.

RESULTS

The concordance between high-density TMAs and whole sections was 61 of 77 (79%) for cytokeratin 19; 76 of 80 (95%) for HBME 1; and 67 of 75 (89%) for CITED1. The concordance between the low-density TMAs and whole sections was cytokeratin 19, 41 of 51 (80%) for cytokeratin 19; HBME1, 52 of 56 (92.8%) for HBME1 and 58 of 59 (98%) for CITED1. The most frequent discordance was negative core but positive focal heterogeneous protein expression in whole sections. On whole sections, the sensitivity of tests increased but the specificity decreased compared to TMAs; however, the accuracy remained similar (77%-83%).

CONCLUSION

Focal and heterogeneous protein expression was the most frequent reason for false negative results in TMAs. Tissue microarray remains an accurate method of screening for protein expression in a large number of thyroid tissues irrespective of core diameters or grid densities.

Gene expression profile of human thyroid cancer in relation to its mutational status

This review describes the gene expression profile changes associated with the presence of different mutations that contribute to thyroid cell carcinogenesis. The results are discussed in the context of thyroid cancer biology and of the implications for disease prognosis, while the diagnostic aspect has been omitted. For papillary thyroid cancer (PTC), the most characteristic gene expression profile is associated with the presence of BRAF mutation. BRAF-associated PTC differ profoundly from RET/PTC or RAS-associated cancers. Simultaneously, they retain many characteristic gene expression features common for all PTCs, induced by the alternative mutations activating MAPK pathway. Although the difference between papillary and follicular thyroid cancer (FTC) is significant at the gene expression profile level, surprisingly, the RAS-related signature of FTC is not well specified. PAX8/peroxisome proliferator-activated receptor γ (PPARγ) rearrangements, which occur in FTC as an alternative to the RAS mutation, are associated with specific changes in gene expression. Furthermore, the difference between well-differentiated thyroid cancers and poorly differentiated and anaplastic thyroid cancers is mainly a reflection of tumor degree of differentiation and may not be attributed to the presence of characteristic mutations.

Aberrant promoter methylation in overexpression of CITED1 in papillary thyroid cancer

BACKGROUND

More than 80% of all thyroid cancers, the most common endocrine malignancy, are papillary thyroid cancer (PTC). It is well established that CITED1 (Cbp/p300 Interacting Transactivators with glutamic acid [E] and aspartic acid [D]-rich C-terminal domain) mRNA is characteristically overexpressed in PTC. Our previous study suggested a positive association of BRAF mutation with CITED1 overexpression. However, the mechanism of CITED1 expression in PTC remains to be elucidated. In the present study, we analyzed whether aberrant methylation of CITED1 gene promotes CITED1 overexpression in PTC.

METHOD

CITED1 mRNA expression levels were analyzed by quantitative polymerase chain reaction in three PTC-derived cell lines, TPC1, K1, and KTC-1, and in surgically dissected PTC and surrounding normal tissues from 19 patients. The BRAF mutation status of the cells and clinical specimens was determined by direct sequencing. The methylation status of the deoxycitidine-phosphate-deoxyguanosine dinucleotides (CpGs) in the CITED1 promoter was analyzed by the bisulfite-sequencing method using genomic DNA. Finally, the expression of CITED1 mRNA in TPC1 cells, when subjected to pharmacological inhibition of methylation, was analyzed.

RESULTS

CITED1 mRNA was expressed at lower levels in TPC1 than in K1 and KTC-1 cells. A BRAF mutation was present in K1 and KTC-1 cells, but not in TPC1 cells. CITED1 promoter was hypomethylated in K-1 and KTC-1 cells, but not in TPC1 cells. In surgically dissected specimens, the mean expression level of CITED1 mRNA was 30-fold higher in PTC tissues than in normal tissues. CpGs in the CITED1 promoter were more heavily methylated in normal tissues than in PTC tissues. In PTC specimens without a BRAF mutation, two CpGs were more heavily methylated than in PTC specimens with the BRAF V600E mutation. Pharmacological inhibition of methylation in TPC1 cells by 5'-aza-2'-deoxycitidine resulted in increased expression of CITED1 mRNA.

CONCLUSION

Hypomethylation of the CpGs in the promoter region of CITED1 is associated with higher expression of CITED1 mRNA in PTC tissues, consistent with the hypothesis that epigenetic regulation is involved in the overexpression of CITED1. This hypothesis is supported by pharmacologic inhibition studies in TPC1 cells.

The spectrum of papillary thyroid carcinoma variants

Papillary thyroid carcinoma is the most common type of thyroid malignancy. The diagnostic features of these tumors include characteristic nuclear cytology. However, many variants have been reported with different morphology and molecular profiles. Although the vast majority of papillary thyroid carcinomas have an excellent prognosis, some variants of papillary thyroid carcinoma can have a more aggressive course. With this increased attention to papillary thyroid carcinoma variants has come the need to sort out which variants are clinically important and should be recognized by practicing pathologists. The main objectives of this review article are to (1) summarize the gross and histopathologic features of papillary thyroid carcinoma; (2) provide an overview of the subtypes of papillary thyroid carcinoma and their prognosis; (3) discuss established and emerging data on the immunohistochemical findings that are helpful in differential diagnosis; and (4) summarize molecular findings and pathogenesis of these lesions.

Application of immunohistochemistry to thyroid neoplasms

CONTEXT

Thyroid lesions with nodular architecture and follicular pattern of growth often pose difficulties in accurate diagnosis during the assessment of cytologic and histologic specimens. The diagnosis of follicular neoplasm on cytology or of follicular tumor of uncertain malignant potential on histology is likely to cause confusion among clinicians and delay effective management of these lesions. Occasionally, thyroid tumors represent unusual or metastatic lesions and their accurate diagnosis requires immunohistochemical confirmation.

OBJECTIVE

To review the literature on the applications of immunohistochemistry in the differential diagnosis of thyroid tumors.

DATA SOURCES

Relevant articles indexed in PubMed (National Library of Medicine) between 1976 and 2006.

CONCLUSIONS

Our review supports the use of ancillary techniques involving a panel of antibodies suitable for immunohistochemistry and molecular analysis in the assessment of thyroid nodules. These tools can improve diagnostic accuracy when combined with standard morphologic criteria.

CITED1 expression in Wilms' tumor and embryonic kidney

Wilms' tumors, or nephroblastomas, are thought to arise from abnormal postnatal retention and dysregulated differentiation of nephrogenic progenitor cells that originate as a condensed metanephric mesenchyme within embryonic kidneys. We have previously shown that the transcriptional regulator CITED1 (CBP/p300-interacting transactivators with glutamic acid [E]/aspartic acid [D]-rich C-terminal domain) is expressed exclusively in these nephrogenic progenitor cells and is downregulated as they differentiate to form nephronic epithelia. In the current study, we show that CITED1 expression persists in blastemal cell populations of both experimental rat nephroblastomas and human Wilms' tumors, and that primary human Wilms' tumors presenting with disseminated disease show the highest level of CITED1 expression. Unlike the predominantly cytoplasmic subcellular localization of CITED1 in the normal developing kidney, CITED1 is clearly detectable in the nuclear compartment of Wilms' tumor blastema. These findings indicate that CITED1 is a marker of primitive blastema in Wilms' tumors and suggest that persistent expression and/or altered subcellular localization of CITED1 in the condensed metanephric mesenchyme could play a role in Wilms' tumor initiation and pathogenesis.

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.

Cited1 and Cited2 are differentially expressed in the developing kidney but are not required for nephrogenesis

Early kidney development in mammals is characterized by reciprocal tissue interaction between the ureteric bud and the metanephric mesenchyme. The coordinated response to this interaction is regulated largely at the transcriptional level. Here, we investigate the expression and function of Cited1, a transcriptional cofactor that we have previously implicated in kidney development. We show that Cited1 is expressed in the metanephric mesenchyme after invasion of the ureteric bud and that its expression is limited to the cap mesenchyme, those cells that aggregate most tightly around the tip of the ureteric bud and give rise to nephronic epithelium of the adult kidney. Cited1 is down-regulated during the initial stages of epithelial conversion and is not expressed past this progenitor stage. Despite its unique expression pattern, deletion of Cited1 does not disrupt kidney development. We hypothesized that this finding was due to functional redundancy with other members of this gene family. The expression pattern of Cited2 overlaps that of Cited1, but its deletion, either alone or in combination with Cited1, does not disrupt epithelial differentiation of the metanephric mesenchyme. From these studies, we conclude that Cited1 and 2 are dynamically expressed during kidney development, but are not required for nephrogenesis.

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.

Immunohistochemical markers in diagnosis of papillary thyroid carcinoma: Utility of HBME1 combined with CK19 immunostaining

Papillary thyroid carcinoma and its variants can be difficult to distinguish from cellular adenomatous nodules. Prior studies have advocated various antibodies to aid in the differential diagnosis, but there is little agreement on their utility. We undertook this study to evaluate immunohistochemical markers in the diagnosis and differential diagnosis of papillary thyroid carcinoma. Ten cases of papillary thyroid carcinoma were initially stained for HBME1, CK19, fibronectin1, Ki-67, Calretinin, p16, SFTPB and CITED1. Additionally, two previously untested antibodies to molecules that have been found to be upregulated in papillary thyroid carcinoma (CST6 and EPS8) were also evaluated. Of these, only HBME1, CK19 and fibronectin1 showed diagnostic utility. These three markers were then further evaluated in 51 papillary thyroid carcinomas and 57 benign thyroids. HBME1 was the most sensitive and specific marker, staining 49/51 papillary thyroid carcinomas and only 4/57 benign thyroids. CK19 was equally sensitive staining all 51 papillary thyroid carcinomas, but it was nonspecific staining 39 of 57 benign thyroids. A negative result, however, was helpful in excluding papillary thyroid carcinoma. Fibronectin1 was positive in 35/51 papillary thyroid carcinomas (69%) and 4/57 (7%) benign thyroids, but its utility was hampered by high background staining. These findings suggest that the combination of HBME1 and CK19 has the greatest diagnostic utility in the differentiation of papillary thyroid carcinoma from its benign mimics.

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.

The Transcriptional Activity of CITED1 Is Regulated by Phosphorylation in a Cell Cycle-dependent Manner

CITED1 is the founding member of the CITED family of cofactors that are involved in regulating a wide variety of CBP/p300-dependent transcriptional responses. In the present study, we show that the phosphorylation status of CITED1 changes during the cell cycle and affects its transcriptional cofactor activity. Tryptic mapping and mutagenesis studies identified five phosphorylated serine residues in CITED1. Phosphorylation of these residues did not affect CRM1-dependent nuclear export, but did decrease CITED1 binding to p300 and inhibited CITED1-dependent transactivation of Smad4 and p300. These results suggest that CITED1 functions as a cell cycle-dependent transcriptional cofactor whose activity is regulated by phosphorylation.

Molecular markers for discrimination of benign and malignant follicular thyroid tumors

OBJECTIVE

To identify molecular markers useful for the diagnostic discrimination of benign and malignant follicular thyroid tumors.

METHODS

A panel of thyroid tumors was characterized with expression profiling using cDNA microarrays. A robust algorithm for gene selection was developed to identify molecular markers useful for the classification of heterogeneous tumor classes. The study included tumor tissue specimens from 10 patients with benign follicular adenomas and from 10 with malignant tumors. The malignant tumors mainly consisted of clinically relevant minimally invasive follicular carcinomas. The mRNA expression level of a candidate gene, FHL1, was evaluated in an independent series of 61 tumors.

RESULTS

22 gene expression markers were identified as differentially expressed. Several of the identified genes, for example DIO1, CITED1, CA12 and FN1, have previously been observed as differentially expressed in various thyroid tumors. FHL1 was significantly underexpressed in carcinomas compared to adenomas in the independent panel of tumors. The results indicate that a small number of genes can be useful to distinguish follicular adenomas from follicular carcinomas.

CONCLUSIONS

Our findings clearly corroborate previous studies and identify novel candidate molecular markers. These genes have the potential for molecular classification of follicular thyroid tumors and for providing improved understanding of the molecular mechanisms involved in thyroid malignancies.

CITED1 homozygous null mice display aberrant pubertal mammary ductal morphogenesis

Expression microarray analysis identified CITED1 among a group of genes specifically upregulated in the pubertal mouse mammary gland. At puberty, CITED1 localizes to the luminal epithelial cell population of the mammary ducts and the body cells of the terminal end buds. Generation of CITED1 gene knockout mice showed that homozygous null mutants exhibit retarded mammary ductal growth at puberty and, in addition, dilated ductal structures with a lack of spatial restriction of the subtending branches. Analysis of CITED1 homozygous null and heterozygous null mammary gland gene expression using microarrays suggested that the mammary-specific phenotype seen in the homozygous null females is due to a disturbance in the transcription of a number of key mediators of pubertal ductal morphogenesis. These include estrogen and TGFbeta responsive genes, such as the EGFR/ErbB2 ligand, amphiregulin, whose transcription we suggest is directly or indirectly regulated by CITED1.

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).

Cited1 Is a Bifunctional Transcriptional Cofactor That Regulates Early Nephronic Patterning

In a screen to identify factors that regulate the conversion of mesenchyme to epithelium during the early stages of nephrogenesis, it was found that the Smad4-interacting transcriptional cofactor, Cited1, is expressed in the condensed cap mesenchyme surrounding the tip of the ureteric bud (UB), is downregulated after differentiation into epithelia, and has the capacity to block UB branching and epithelial morphogenesis in cultured metanephroi. Cited1 represses Wnt/beta-catenin but activates Smad4-dependent transcription involved in TGF-beta and Bmp signaling. By modifying these pathways, Cited1 may coordinate cellular differentiation and survival signals that regulate nephronic patterning in the metanephros.

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.

Gene Expression Profile of Papillary Thyroid Cancer: Sources of Variability and Diagnostic Implications

The study looked for an optimal set of genes differentiating between papillary thyroid cancer (PTC) and normal thyroid tissue and assessed the sources of variability in gene expression profiles. The analysis was done by oligonucleotide microarrays (GeneChip HG-U133A) in 50 tissue samples taken intraoperatively from 33 patients (23 PTC patients and 10 patients with other thyroid disease). In the initial group of 16 PTC and 16 normal samples, we assessed the sources of variability in the gene expression profile by singular value decomposition which specified three major patterns of variability. The first and the most distinct mode grouped transcripts differentiating between tumor and normal tissues. Two consecutive modes contained a large proportion of immunity-related genes. To generate a multigene classifier for tumor-normal difference, we used support vector machines-based technique (recursive feature replacement). It included the following 19 genes: DPP4, GJB3, ST14, SERPINA1, LRP4, MET, EVA1, SPUVE, LGALS3, HBB, MKRN2, MRC2, IGSF1, KIAA0830, RXRG, P4HA2, CDH3, IL13RA1, and MTMR4, and correctly discriminated 17 of 18 additional PTC/normal thyroid samples and all 16 samples published in a previous microarray study. Selected novel genes (LRP4, EVA1, TMPRSS4, QPCT, and SLC34A2) were confirmed by Q-PCR. Our results prove that the gene expression signal of PTC is easily detectable even when cancer cells do not prevail over tumor stroma. We indicate and separate the confounding variability related to the immune response. Finally, we propose a potent molecular classifier able to discriminate between PTC and nonmalignant thyroid in more than 90% of investigated samples.

Expression profile of malignant and non-malignant diseases of the thyroid gland reveals altered expression of a common set of genes in goiter and papillary carcinomas

Using cDNA microarrays with 3800 cDNA fragments, we determined the expression profile of normal thyroid tissue, goiter, adenoma and papillary carcinoma (10 samples from each class). After background correction and statistical analysis, we identified a set of 160 genes as being differentially expressed in all pair-wise comparisons. Here we demonstrate that, at least on the basis of these differentially expressed genes, a positive correlation between goiter and papillary carcinomas could be observed. We identified a common set of genes whose expression is diminished in both goiter and papillary carcinomas as compared to normal thyroid tissue. Moreover, no genes with inverse correlation in samples from goiter and papillary carcinomas could be detected. Using Real-Time PCR and/or tissue microarrays, we confirmed the altered expression of some of the identified genes. Of notice, we demonstrate that the reduced mRNA levels of p27(kip1) observed in papillary carcinomas as compared to either goiter or normal thyroid tissues (P<0.001) is accompanied by an altered protein distribution within the cell. In papillary carcinomas, P27(KIP1) is preferentially cytoplasmic as opposed to goiter or normal thyroid tissue, where P27(KIP1) is preferentially located in the nucleus. The exploitation of the data presented here could contribute to the understanding of the molecular events related to thyroid diseases and gives support to the notion that common molecular events might be related to the frequent observation of areas of papillary carcinomas in the gland of patients with goiter.

The role of immunohistochemical markers in the diagnosis of follicular-patterned lesions of the thyroid

Thyroid nodules are extremely common in the general population. The differential diagnosis includes numerous entities, non-neoplastic and neoplastic, benign and malignant. However, the diagnosis of follicular-patterned lesions remains an area fraught with controversy and diagnostic criteria are highly variable. It is, therefore, a field in need of objective, scientific markers that better characterize these lesions than has been possible by classical morphology. A number of candidates have been proposed. No single marker can identify all malignant follicular-patterned lesions, however, various combinations have been proposed. They include HBME-1, high molecular weight cytokeratins and ret, galectin-3 and TPO, galectin-3, fibronectin-1, CITED-1, HBME-1, and CK19. Advances in our understanding of the molecular basis of thyroid cancer will allow the identification of new markers and more accurate characterization of specific subtypes of neoplasia and malignancy. As new markers are characterized and validated, directed by molecular profiling of thyroid lesions with characteristic morphology, behavior, and outcome, they will become available as routine immunohistochemical markers that will provide a more accurate, scientific, and clinically relevant consultation report from the pathologist for cytology and surgical pathology procedures. Application of these markers will enhance the diagnosis of thyroid nodules and better guide the management of patients with these lesions.