Thyroid-specific transcription factors and their roles in thyroid cancer

Biomarker identification of medullary thyroid carcinoma from gene expression profiles considering without-treatment and with-treatment studies-A bioinformatics approach

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor derived from parafollicular thyroid gland cells. In both hereditary MTC and sporadic forms, genetic changes result in fundamental changes, and prognosis and mutational status are highly correlated. In this work, biomarker genes (DEGs and DEmiRNAs) for MTC will be computationally identified in order to help in their diagnosis and treatment. The gene expression profiles of two different types of studies, namely without-treatment (wo-trt) and with-treatment (w-trt), are considered for discovering biomarkers. The datasets were retrieved from the GEO database, and the DEGs and DEmiRNAs were analyzed using ExpressAnalyst and GEO2R. The functional analysis of DEGs and DEmiRNAs was performed, and most of the pathways enriched related to thyroid oncological pathways such as MAPK pathway,mTOR pathway, and PI3K-AKT Signaling pathway. Through this conclusion, the RET gene was upregulated wo-trt; the dinaciclib treatment RET gene was down-regulated computationally. To optimize the therapeutic targeting of RET, greater research into the mechanisms regulating RET transcription is necessary.

BRAF mutation, selected miRNAs and genes expression in primary papillary thyroid carcinomas and local lymph node metastases

Mutations in cancer-related genes are now known to be accompanied by epigenetic events in carcinogenesis by modification of the regulatory pathways and expression of genes involved in the pathobiology. Such cancer-related mutations, miRNAs and gene expression may be promising molecular markers of the most common papillary thyroid carcinoma (PTC). However, there are limited data on their relationships. The aim of this study was to analyse the interactions between BRAF mutations, selected microRNAs (miR-21, miR-34a, miR-146b, and miR-9) and the expression of selected genes (LGALS3, NKX2-1, TACSTD2, TPO) involved in the pathogenesis of PTC. The study cohort included 60 primary papillary thyroid carcinomas (PTC) that were classified as classical (PTC/C; n=50) and invasive follicular variant (PTC/F; n=10), and 40 paired lymph node metastases (LNM). BRAF mutation status in primary and recurrent/persistent papillary thyroid carcinomas was determined. The mutation results were compared both between primary and metastatic cancer tissue, and between BRAF mutation status and selected genes and miRNA expression in primary PTC. Furthermore, miRNAs and gene expression were compared between primary PTCs and non-neoplastic tissue, and local lymph node metastatic tumor, respectively. All studied markers showed several significant mutual interactions and contexts. In conclusion, to the best our knowledge, this is the first integrated study of BRAF mutational status, the expression levels of mRNAs of selected genes and miRNAs in primary PTC, and paired LNM.

Reactivation of embryonic genetic programs in tissue regeneration and disease

Embryonic genetic programs are reactivated in response to various types of tissue damage, providing cell plasticity for tissue regeneration or disease progression. In acute conditions, these programs remedy the damage and then halt to allow a return to homeostasis. In chronic situations, including inflammatory diseases, fibrosis and cancer, prolonged activation of embryonic programs leads to disease progression and tissue deterioration. Induction of progenitor identity and cell plasticity, for example, epithelial-mesenchymal plasticity, are critical outcomes of reactivated embryonic programs. In this Review, we describe molecular players governing reactivated embryonic genetic programs, their role during disease progression, their similarities and differences and lineage reversion in pathology and discuss associated therapeutics and drug-resistance mechanisms across many organs. We also discuss the diversity of reactivated programs in different disease contexts. A comprehensive overview of commonalities between development and disease will provide better understanding of the biology and therapeutic strategies.

Development of Novel Murine BRAFV600E-Driven Papillary Thyroid Cancer Cell Lines for Modeling of Disease Progression and Preclinical Evaluation of Therapeutics

The Cancer Genome Atlas study in thyroid cancer exposed the genomic landscape of ~500 PTCs and revealed BRAFV600E-mutant tumors as having different prognosis, contrasting indolent cases and those with more invasive disease. Here, we describe the generation and characterization of six novel BRAFV600E-driven papillary thyroid cancer (PTC) cell lines established from a BrafV600E+/-/Pten+/-/TPO-Cre mouse model that spontaneously develop thyroid tumors. The novel cell lines were obtained from animals representing a range of developmental stages and both sexes, with the goal of establishing a heterogeneous panel of PTC cell lines sharing a common driver mutation. These cell lines recapitulate the genetics and diverse histopathological features of BRAFV600E-driven PTC, exhibiting differing degrees of growth, differentiation, and invasive potential that may help define mechanisms of pathogenesis underlying the heterogeneity present in the patient population. We demonstrate that these cell lines can be used for a variety of in vitro applications and can maintain the potential for in vivo transplantation into immunocompetent hosts. We believe that these novel cell lines will provide powerful tools for investigating the molecular basis of thyroid cancer progression and will lead to the development of more personalized diagnostic and treatment strategies for BRAFV600E-driven PTC.

Weighted gene co-expression network reveals driver genes contributing to phenotypes of anaplastic thyroid carcinoma and immune checkpoint identification for therapeutic targets

Background

Anaplastic thyroid carcinoma (ATC) is a rare but extremely malignant tumor, with a rapid growth rate and early metastasis thus leading to poor survival of patients. The molecular mechanisms underlying these aggressive traits of ATC remain unknown, which impedes the substantial progress in treatment to prolong ATC patient survival.

Methods

We applied weighted gene co-expression network analysis (WGCNA) to identify ATC-specific modules. The Metascape web and R package clusterProfiler were employed to perform enrichment analysis. Combined with differentially expressed gene analysis, we screened out the most potential driver genes and validated them using receiver operator characteristic (ROC) analysis, quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blotting, immunohistochemistry (IHC), and triple immunofluorescence staining.

Results

A gene expression matrix covering 75 normal samples, 83 papillary thyroid carcinoma (PTC), 26 follicular thyroid carcinoma (FTC), 19 poor-differentiated thyroid carcinoma (PDTC), and 41 ATC tissue samples were integrated, based on which we detected three most potential ATC-specific modules and found that hub genes of these modules were enriched in distinct biological signals. Hub genes in the turquoise module were mainly enriched in mitotic cell cycle, tube morphogenesis, and cell differentiation, hub genes in the magenta module were mainly clustered in the extracellular matrix organization, positive regulation of cell motility, and regulation of Wnt signaling pathway, while hub genes in the blue module primarily participated in the inflammatory response, innate immune response, and adaptive immune response. We showed that 9 top genes, 8 transcription factors (TFs), and 4 immune checkpoint genes (ICGs) were differentially expressed in ATC compared to other thyroid samples and had high diagnostic values for ATC, among which, 9 novel ATC-specific genes (ADAM12, RNASE2, CASP5, KIAA1524, E2F7, MYBL1, SRPX2, HAVCR2, and TDO2) were validated with our clinical samples. Furthermore, we illustrated that ADAM12, RNASE2, and HAVCR2 were predominantly present in the cytoplasm.

Conclusion

Our study identified a set of novel ATC-specific genes that were mainly related to cell proliferation, invasion, metastasis, and immunosuppression, which might throw light on molecular mechanisms underlying aggressive phenotypes of ATC and provide promisingly diagnostic biomarkers and therapeutic targets.

Mutational and bioinformatics analysis of the NKX2.1 gene in a cohort of Iranian pediatric patients with congenital hypothyroidism (CH)

Congenital hypothyroidism (CH) occurs with a relatively alarming prevalence in infants, and if not diagnosed and treated in time, it can have devastating consequences for the development of the nervous system. CH is associated with genetic changes in several genes that encode transcription factors responsible for thyroid development, including mutations in the NK2 homeobox 1 (NKX2.1) gene, which encodes the thyroid transcription factor-1 (TTF-1). Although CH is frequently observed in pediatric populations, there is still a limited understanding of the genetic factors and molecular mechanisms contributing to this disease. The sequence of the NKX2.1 gene was investigated in 75 pediatric patients with CH by polymerase chain reaction (PCR), single-stranded conformation polymorphism (SSCP), and direct DNA sequencing. Four missense heterozygous variations were identified in exon 3 of the NKX2.1 gene, including three novel missense variations, namely c.708A>G, p.Gln202Arg; c.713T>G, p.Tyr204Asp; c.833T>G, p.Tyr244Asp, and a previously reported variant rs781133468 (c.772C>G, p.His223Gln). Importantly, these variations occur in highly conserved residues of the TTF-1 DNA-binding domain and were predicted by bioinformatics analysis to alter the protein structure, with a probable alteration in the protein function. These results indicate that nucleotide changes in the NKX2.1 gene may contribute to CH pathogenesis.

Mutational and bioinformatics analysis of the NKX2.1 gene in a cohort of Iranian pediatric patients with congenital hypothyroidism (CH)

Congenital hypothyroidism (CH) occurs with a relatively alarming prevalence in infants, and if not diagnosed and treated in time, it can have devastating consequences for the development of the nervous system. CH is associated with genetic changes in several genes that encode transcription factors responsible for thyroid development, including mutations in the NK2 homeobox 1 (NKX2.1) gene, which encodes the thyroid transcription factor-1 (TTF-1). Although CH is frequently observed in pediatric populations, there is still a limited understanding of the genetic factors and molecular mechanisms contributing to this disease. The sequence of the NKX2.1 gene was investigated in 75 pediatric patients with CH by polymerase chain reaction (PCR), single-stranded conformation polymorphism (SSCP), and direct DNA sequencing. Four missense heterozygous variations were identified in exon 3 of the NKX2.1 gene, including three novel missense variations, namely c.708A>G, p.Gln202Arg; c.713T>G, p.Tyr204Asp; c.833T>G, p.Tyr244Asp, and a previously reported variant rs781133468 (c.772C>G, p.His223Gln). Importantly, these variations occur in highly conserved residues of the TTF-1 DNA-binding domain and were predicted by bioinformatics analysis to alter the protein structure, with a probable alteration in the protein function. These results indicate that nucleotide changes in the NKX2.1 gene may contribute to CH pathogenesis.

Genetic susceptibility to hereditary non-medullary thyroid cancer

Non-medullary thyroid cancer (NMTC) is the most common type of thyroid cancer. With the increasing incidence of NMTC in recent years, the familial form of the disease has also become more common than previously reported, accounting for 5-15% of NMTC cases. Familial NMTC is further classified as non-syndromic and the less common syndromic FNMTC. Although syndromic NMTC has well-known genetic risk factors, the gene(s) responsible for the vast majority of non-syndromic FNMTC cases are yet to be identified. To date, several candidate genes have been identified as susceptibility genes in hereditary NMTC. This review summarizes genetic predisposition to non-medullary thyroid cancer and expands on the role of genetic variants in thyroid cancer tumorigenesis and the level of penetrance of NMTC-susceptibility genes.

Emerging Biomarkers in Thyroid Practice and Research

Simple Summary

Tumor biomarkers are molecules at genetic or protein level, or certain evaluable characteristics. These help in perfecting patient management. Over the past decade, advanced and more sensitive techniques have led to the identification of many new biomarkers in the field of oncology. A knowledge of the recent developments is essential for their application to clinical practice, and furthering research. This review provides a comprehensive account of such various markers identified in thyroid carcinoma, the most common endocrine malignancy. While some of these have been brought into use in routine patient management, others are novel and need more research before clinical application.

Abstract

Thyroid cancer is the most common endocrine malignancy. Recent developments in molecular biological techniques have led to a better understanding of the pathogenesis and clinical behavior of thyroid neoplasms. This has culminated in the updating of thyroid tumor classification, including the re-categorization of existing and introduction of new entities. In this review, we discuss various molecular biomarkers possessing diagnostic, prognostic, predictive and therapeutic roles in thyroid cancer. A comprehensive account of epigenetic dysregulation, including DNA methylation, the function of various microRNAs and long non-coding RNAs, germline mutations determining familial occurrence of medullary and non-medullary thyroid carcinoma, and single nucleotide polymorphisms predisposed to thyroid tumorigenesis has been provided. In addition to novel immunohistochemical markers, including those for neuroendocrine differentiation, and next-generation immunohistochemistry (BRAF V600E, RAS, TRK, and ALK), the relevance of well-established markers, such as Ki-67, in current clinical practice has also been discussed. A tumor microenvironment (PD-L1, CD markers) and its influence in predicting responses to immunotherapy in thyroid cancer and the expanding arena of techniques, including liquid biopsy based on circulating nucleic acids and plasma-derived exosomes as a non-invasive technique for patient management, are also summarized.

NKX2-1 re-expression induces cell death through apoptosis and necrosis in dedifferentiated thyroid carcinoma cells

NK2 homeobox 1 (NKX2-1) is a thyroid transcription factor essential for proper thyroid formation and maintaining its physiological function. In thyroid cancer, NKX2-1 expression decreases in parallel with declined differentiation. However, the molecular pathways and mechanisms connecting NKX2-1 to thyroid cancer phenotypes are largely unknown. This study aimed to examine the effects of NKX2-1 re-expression on dedifferentiated thyroid cancer cell death and explore the underlying mechanisms. A human papillary thyroid carcinoma cell line lacking NKX2-1 expression was infected with an adenoviral vector containing Nkx2-1. Cell viability decreased after Nkx2-1 transduction and apoptosis and necrosis were detected. Arginase 2 (ARG2), regulator of G protein signaling 4 (RGS4), and RGS5 mRNA expression was greatly increased in Nkx2-1-transducted cells. After suppressing these genes by siRNA, cell death, apoptosis, and necrosis decreased in RGS4 knockdown cells. These findings demonstrated that cell death was induced via apoptosis and necrosis by NKX2-1 re-expression and involves RGS4.

Development of Functional Thyroid C Cell-like Cells from Human Pluripotent Cells in 2D and in 3D Scaffolds

Medullary thyroid carcinoma contributes to about 3–4% of thyroid cancers and affects C cells rather than follicular cells. Thyroid C cell differentiation from human pluripotent stem cells has not been reported. We report the stepwise differentiation of human embryonic stem cells into thyroid C cell-like cells through definitive endoderm and anterior foregut endoderm and ultimobranchial body-like intermediates in monolayer and 3D Matrigel culture conditions. The protocol involved sequential treatment with interferon/transferrin/selenium/pyruvate, foetal bovine serum, and activin A, then IGF-1 (Insulin-like growth factor 1), on the basis of embryonic thyroid developmental sequence. As well as expressing C cell lineage relative to follicular-lineage markers by qPCR (quantitative polymerase chain reaction) and immunolabelling, these cells by ELISA (enzyme-linked immunoassay) exhibited functional properties in vitro of calcitonin storage and release of calcitonin on calcium challenge. This method will contribute to developmental studies of the human thyroid gland and facilitate in vitro modelling of medullary thyroid carcinoma and provide a valuable platform for drug screening.

A Positive Feedback Loop Between DICER1 and Differentiation Transcription Factors Is Important for Thyroid Tumorigenesis

Background: DICER1 plays a central role in microRNA biogenesis and functions as a tumor suppressor in thyroid cancer, which is the most frequent endocrine malignancy with a rapidly increasing incidence. Thyroid cancer progression is associated with loss of cell differentiation and reduced expression of thyroid differentiation genes and response to thyrotropin (TSH). Here we investigated whether a molecular link exists between DICER1 and thyroid differentiation pathways. Methods: We used bioinformatic tools to search for transcription factor binding sites in the DICER1 promoter. DICER1, NKX2-1, PAX8, and CREB expression levels were evaluated by gene and protein expression in vitro and by interrogation of The Cancer Genome Atlas (TCGA) thyroid cancer data. Transcription factor binding and activity were assayed by chromatin immunoprecipitation, band-shift analysis, and promoter-reporter gene activity. Gene-silencing and overexpression approaches were used to elucidate the functional link between DICER1 and differentiation. Results: We identified binding sites for NKX2-1 and CREB within the DICER1 promoter and found that both transcription factors are functional in thyroid cells. TSH induced DICER1 expression in differentiated thyroid cells, at least in part, through the cAMP/PKA/CREB pathway. TCGA analysis revealed a significant positive correlation between CREB and DICER1 expression in human thyroid tumors. NKX2-1 overexpression increased DICER1 promoter activity and expression in vitro, and this was significantly greater in the presence of CREB and/or PAX8. Gain- and loss-of-function assays revealed that DICER1 regulates NKX2-1 expression in thyroid tumor cells and vice versa, thus establishing a positive feedback loop between both proteins. We also found a positive correlation between NKX2-1 and DICER1 expression in human thyroid tumors. DICER1 silencing decreased PAX8 expression and, importantly, the expression and activity of the sodium iodide symporter, which is essential for the diagnostic and therapeutic use of radioiodine in thyroid cancer. Conclusions: The differentiation transcription factors NKX2.1, PAX8, and CREB act in a positive feedback loop with DICER1. As the expression of these transcription factors is markedly diminished in thyroid cancer, our findings suggest that DICER1 downregulation in this cancer is mediated, at least partly, through impairment of its transcription.

Development of Novel Follicular Thyroid Cancer Models Which Progress to Poorly Differentiated and Anaplastic Thyroid Cancer

Recent developments in thyroid cancer research have been hindered by a lack of validated in vitro models, allowing for preclinical experimentation and the screening of prospective therapeutics. The goal of this work is to develop and characterize three novel follicular thyroid cancer (FTC) cell lines developed from relevant animal models. These cell lines recapitulate the genetics and histopathological features of FTC, as well as progression to a poorly differentiated state. We demonstrate that these cell lines can be used for a variety of in vitro applications and maintain the potential for in vivo transplantation into immunocompetent hosts. Further, cell lines exhibit differing degrees of dysregulated growth and invasive behavior that may help define mechanisms of pathogenesis underlying the heterogeneity present in the patient population. We believe these novel cell lines will provide powerful tools for investigating the molecular basis of thyroid cancer progression and lead to the development of more personalized diagnostic and treatment strategies.

The Role of Lithium in Management of Endocrine Tumors-A Comprehensive Review

Background: Epidemiological data reveal that treatment with lithium, a mood stabilizer, is associated with decreased incidence and mortality of certain cancer types, such as melanoma. Therefore, repositioning of lithium as an anticancer agent has emerged as a promising strategy in oncology. Since lithium affects the physiology of several endocrine tissues, the goal of this study was to analyze the role of lithium in the pathogenesis and treatment of tumors of the endocrine system. Methods: The databases of PubMed, EMBASE, MEDLINE, were searched from January 1970 through February 2019 for articles including the keywords "lithium and"-"thyroid cancer," "thyroid nodule," "parathyroid adenoma," "parathyroid carcinoma," "pituitary adenoma," "pituitary neuroendocrine tumor," "neuroendocrine tumor," "carcinoid," "adrenal adenoma," "adrenal carcinoma," "pheochromocytoma/paraganglioma." Preclinical in vitro and in vivo studies as well as case series, retrospective cohort studies and prospective trials were selected for the analysis. Results: Treatment with lithium has been associated with a higher prevalence of thyroid enlargement, hypothyroidism and increased calcium levels due to parathyroid adenoma or hyperplasia, as one of the mechanisms of its action is to stimulate proliferation of normal follicular thyroid and parathyroid cells via activation of the Wnt signaling pathway. Supratherapeutic concentrations of lithium decrease the activity of glycogen synthase kinase-3β (GSK-3β), leading to cell cycle arrest in several in vitro cancer models including medullary thyroid cancer (TC), pheochromocytoma/paraganglioma and carcinoid. Growth inhibitory effects of lithium in vivo have been documented in medullary TC xenograft mouse models. Clinically, lithium has been used as an adjuvant agent to therapy with radioactive iodine (RAI), as it increases the residence time of RAI in TC. Conclusion: Patients chronically treated with lithium need to be screened for hypothyroidism, goiter, and hyperparathyroidism, as the prevalence of these endocrine abnormalities is higher in lithium-treated patients than in the general population. The growth inhibitory effects of lithium in medullary TC, pheochromocytoma/paraganglioma and carcinoid were achieved with supratherapeutic concentrations of lithium thus limiting its translational perspective. Currently available clinical data on the efficacy of lithium in the therapy of endocrine tumors in human is limited and associated with conflicting results.

Fine mapping of 14q13 reveals novel variants associated with different histological subtypes of papillary thyroid carcinoma

The first two genome wide association studies (GWAS) of papillary thyroid carcinoma (PTC) detected five variants associated with PTC. Two of them (rs944289 and rs116909374) are located at 14q13 making that locus an important target of research into the genetic predisposition to PTC. We aimed at uncovering other variants at 14q13 associated with PTC independently from the GWAS variants. We performed next generation sequencing of the 14q13 region and analyzed the allele frequencies of single nucleotide polymorphisms (SNPs) in n = 90 PTC cases vs. n = 379 EUR controls from the 1,000 Genome Project. The variants associated with PTC were validated in an Ohio cohort of n = 1,216 PTC cases and n = 1,416 controls. Next, we analyzed the association between SNPs and expression of nearby genes and clinical parameters. We showed that rs368187 was associated with PTC (OR = 1.31, p = 2.20 × 10^-6 ). Rs1632250, Rs1863347 and rs1755787 showed association with classical PTC (cPTC) (n = 891; OR = 1.24, 2.22 × 10^-3 , OR = 1.31, p = 2.15 × 10^-4 and OR = 1.24, p = 2.06 × 10^-3 , respectively) while variant rs28397092 showed association with follicular variant (n = 243; OR = 1.51, p = 1.36 × 10^-3 ). Rs1863347 was associated with suppression of PTCSC3 in unaffected thyroid tissue (p = 0.026). Rs1632250, rs1863347 and rs1755787 showed association with multifocality (OR = 1.85, p = 0.001, OR = 1.98, p = 0.001 and OR = 1.76, p = 0.003 respectively) and N stage (OR = 1.79, p = 0.014, OR = 1.73, p = 0.023 and OR = 1.81, p = 0.013, respectively) in microPTC (n = 328) while rs368187 was associated with M stage (OR = 0.56, p = 0.034) in cPTC. Our results disclose multiple variants associated with PTC and clinical features in the 14q13 superlocus. We suggest that translational genotype/phenotype studies should take into account not only somatic mutations but also germline variants.

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.

A Concise Atlas of Thyroid Cancer Next-Generation Sequencing Panel ThyroSeq v.2

The next-generation sequencing technology allows high out-put genomic analysis. An innovative assay in thyroid cancer, ThyroSeq® was developed for targeted mutation detection by next generation sequencing technology in fine needle aspiration and tissue samples. ThyroSeq v.2 next generation sequencing panel offers simultaneous sequencing and detection in >1000 hotspots of 14 thyroid cancer-related genes and for 42 types of gene fusions known to occur in thyroid cancer. ThyroSeq is being increasingly used to further narrow the indeterminate category defined by cytology for thyroid nodules. From a surgical perspective, genomic profiling also provides prognostic and predictive information and closely relates to determination of surgical strategy. Both the genomic analysis technology and the informatics for the cancer genome data base are rapidly developing. In this paper, we have gathered existing information on the thyroid cancer-related genes involved in the initiation and progression of thyroid cancer. Our goal is to assemble a glossary for the current ThyroSeq genomic panel that can help elucidate the role genomics play in thyroid cancer oncogenesis.

Association between FOXP3 gene polymorphisms and risk of differentiated thyroid cancer in Chinese Han population

BACKGROUND

Foxp3 plays important roles in autoimmune and inflammatory diseases as well as human malignancies. This study aimed to investigate the association between Foxp3 gene polymorphisms and the susceptibility to differentiated thyroid cancers (DTC).

METHODS

Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 350 DTC patients and 306 healthy controls. FOXP3 relative expression was measured by real-time quantitative PCR (qRT-PCR).

RESULTS

AA/AC genotype of Foxp3-rs3761548 was associated with a higher risk of DTC. The frequency of Foxp3-rs2280883 CC/CT genotype was lower in DTC patients. Besides, the AA/AC genotype of rs3761548 was more frequent in female DTC than male DTC. The association between two single nucleotide polymorphisms (SNPs) and clinical characteristics of DTC was further analyzed. We found that rs3761548 AA/AC genotype was more frequent in severe DTC patients (tumor diameter >1 cm) compared with the relative tender DTC patients (tumor diameter <1 cm). On the contrast, the frequency of rs2280883 CC/CT genotype was lower in severe DTC patients. In addition, the Foxp3 relative expression in DTC with AA/AC genotype of rs3761548 was higher than that of DTC with CC genotype.

CONCLUSION

Our findings suggested that Foxp3 polymorphisms were associated with the risk of DTC in Chinese Han population.

Aberrant Methylation of FOXE1 Contributes to a Poor Prognosis for Patients with Colorectal Cancer

BACKGROUND

Hypermethylation of DNA silences gene expression and is an important event in colorectal cancer (CRC). This study aimed to identify aberrantly methylated genes that contribute to a poor prognosis for patients with CRC.

METHODS

The study comprehensively explored DNA methylation microarray profiles from 396 CRC samples and 45 normal control samples in a database and selected aberrantly methylated transcription factors associated with prognosis and metastasis. Using quantitative reverse transcription polymerase chain reaction, the identified genes in 140 patients with CRC were validated to assess the relationship between expression of methylated genes and prognosis.

RESULTS

In the study, FOXE1 was newly identified as a gene associated with prognosis and metastasis in CRC. Expression of FOXE1 in CRC tissues was significantly lower than in normal colorectal tissues (p = 0.01). The survival rate for the patients with low expression of FOXE1 was significantly lower than that for patients with high expression of FOXE1 in uni- and multivariate analyses. Inhibition of DNA methylation recovered FOXE1 expression in CRC cells.

CONCLUSIONS

Methylation-mediated silencing of FOXE1 expression was shown to be a potential prognostic factor in CRC.

Gene expression of thyroid-specific transcription factors may help diagnose thyroid lesions but are not determinants of tumor progression

PURPOSE

The role of thyroid-specific transcription factors in thyroid malignancy is still poorly understood, so we investigate thyroid-specific transcription factors gene expression both in benign and in malignant thyroid nodules, aiming to study a possible clinical utility of these molecules.

METHODS

We quantified TTF-1, FOXE1 and PAX8 mRNA levels, relating their expression to diagnostic and prognostic features of thyroid tumors. RNA was extracted from 4 normal thyroid tissues, 101 malignant [99 papillary thyroid carcinomas (PTC) and 2 anaplastic thyroid carcinomas] and 99 benign thyroid lesion tissues [49 goiter and 50 follicular adenomas (FA)].

RESULTS

Levels of mRNA of both FOXE1 (P < 0.0001) and PAX8 (P < 0.0001) genes, but not TTF-1 (P = 0.7056), were higher in benign than in malignant thyroid lesions. FOXE1 was able to identify malignant nodules with 75.8 % sensitivity, 76.1 % specificity, 75.8 % positive predictive value, 76.1 % negative predictive value and 75.9 % accuracy. PAX8 was able to identify malignancy with 60.6 % sensitivity, 81.1 % specificity, 76.9 % positive predictive value, 66.4 % negative predictive value and 70.6 % accuracy. Both FOXE1 and PAX8 gene expression patterns were also able to differentiate FA from the follicular variant of PTC-FVPTC. However, the investigated gene expression was neither associated with any clinical feature of tumor aggressiveness nor associated with recurrence or survival.

CONCLUSIONS

We suggest that FOXE1 and PAX8 gene expression patterns may help to diagnose thyroid nodules, identifying malignancy and characterizing follicular-patterned thyroid lesions, but are not determinants of thyroid tumor progression.

Effect of triclosan, triclocarban, 2,2',4,4'-tetrabromodiphenyl ether, and bisphenol A on the iodide uptake, thyroid peroxidase activity, and expression of genes involved in thyroid hormone synthesis

Triclosan, triclocarban, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), and bisphenol A (BPA) have been reported to disturb thyroid hormone (TH) homeostasis. We have examined the effects of these chemicals on sodium/iodide symporter (NIS)-mediated iodide uptake and the expression of genes involved in TH synthesis in rat thyroid follicular FRTL-5 cells, and on the activity of thyroid peroxidase (TPO) using rat thyroid microsomes. All four chemicals inhibited NIS-mediated iodide uptake in a concentration-dependent manner. A decrease in the iodide uptake was also observed in the absence of sodium iodide. Kinetic studies showed that all four chemicals were non-competitive inhibitors of NIS, with the order of Ki values being triclosan<triclocarban<BDE-47<BPA. The transcriptional expression of three genes involved in TH synthesis, Slc5a5, Tpo, and Tgo, and three thyroid transcription factor genes, Pax8, Foxe1, and Nkx2-1, was examined using quantitative real-time PCR. No significant changes in the expression of any genes were observed with triclosan or triclocarban. BDE-47 decreased the level of Tpo, while BPA altered the expression of all six genes. Triclosan and triclocarban inhibited the activity of TPO at 166 and >300 μM, respectively. Neither BDE-47 nor BPA affected TPO activity. In conclusion, triclosan, triclocarban, BDE-47, and BPA inhibited iodide uptake, but had differential effects on the expression of TH synthesis-related genes and the activity of TPO.

Replication and Meta-Analysis of Common Gene Mutations in TTF1 and TTF2 with Papillary Thyroid Cancer

Papillary thyroid cancer (PTC), one of the most common malignant thyroid tumors, exits widely in the thyroid of adolescents. Thyroid transcription factor 1 (TTF1) and 2 (TTF2) were thyroid-specific transcription factors, and regulated expression of the thyroid-specific genes. Hence, the aim of the present study was to evaluate the correlation between gene variants of TTF1 and TTF2 and the risk of PTC in Chinese population.Two tagging single-nucleotide polymorphisms (tSNPs) on TTF1 and TTF2 were selected and genotyped by matrix-assisted laser desorption/ionization time-of-flight (MALDITOF) mass spectrometry in a hospital-based case-control study of 297 PTC patients and 594 healthy controls. Furthermore, a meta-analysis of the association between TTF1 and TTF2 and PTC risk was also performed.We found that the rs944289 on the TTF1 was significantly associated with increased PTC risk (TT vs CC, OR = 1.53, 95% CI = 1.05-2.24; CT + TT vs TT, OR = 1.34, 95% CI = 1.00-1.79; T vs C, OR = 1.27, 95% CI = 1.04-1.55). Similarly, the rs965513 on the TTF2 can also elevate the risk of PTC significantly (GA vs GG, OR = 1.67, 95% CI = 1.07-2.59; AA+GA vs AA, OR = 1.37, 95% CI = 1.09-1.82; A vs G, OR = 1.29, 95% CI = 1.05-1.59). Furthermore, results of stratified analysis revealed that the risk effects of rs944289 and rs965513 were more overpowering in the subgroups of patients with MNG, as well as subjects without metastasis. Results of meta-analysis from the previous study and our new data indicated that variants of rs944289 and rs965513 might be the genetic susceptible factors both in Asians and Caucasians.We get the conclusion that mutations of TTF1 and TTF2 are significantly associated with an increasing risk of PTC in Chinese. However, more detailed investigations and further large-scale studies on genetic functions to provide more conclusive and accurate evidence are required in the future.

Novel analogs targeting histone deacetylase suppress aggressive thyroid cancer cell growth and induce re-differentiation

To develop novel therapies for aggressive thyroid cancers, we have synthesized a collection of histone deacetylase (HDAC) inhibitor analogs named AB1 to AB13, which have different linkers between a metal chelating group and a hydrophobic cap. The purpose of this study was to screen out the most effective compounds and evaluate the therapeutic efficacy. AB2, AB3 and AB10 demonstrated the lowest half-maximal inhibitory concentration (IC50) values in one metastatic follicular and two anaplastic thyroid cancer cell lines. Treatment with each of the three ABs resulted in an increase in apoptosis markers, including cleaved poly adenosine diphosphate ribose polymerase (PARP) and cleaved caspase 3. Additionally, the expression of cell-cycle regulatory proteins p21(WAF1) and p27(Kip1) increased with the treatment of ABs while cyclin D1 decreased. Furthermore, AB2, AB3 and AB10 were able to induce thyrocyte-specific genes in the three thyroid cancer cell lines indicated by increased expression levels of sodium iodide symporter, paired box gene 8, thyroid transcription factor 1 (TTF1), TTF2 and thyroid-stimulating hormone receptors. AB2, AB3 and AB10 suppress thyroid cancer cell growth via cell-cycle arrest and apoptosis. They also induce cell re-differentiation, which could make aggressive cancer cells more susceptible to radioactive iodine therapy.

Identification of a novel germline FOXE1 variant in patients with familial non-medullary thyroid carcinoma (FNMTC)

The familial forms of non-medullary thyroid carcinoma (FNMTC) represent approximately 5 % of thyroid neoplasms. Nine FNMTC susceptibility loci have been mapped; however, only the DICER1 and SRGAP1 susceptibility genes have been identified. The transcription factors NKX2-1, FOXE1, PAX8, and HHEX are involved in the morphogenesis and differentiation of the thyroid. Recent studies have identified NKX2-1 germline mutations in FNMTC families. However, the role of high-penetrant FOXE1 variants in FNMTC etiology remains unclear. The aim of this study was to investigate the role of FOXE1 germline mutations in the pathogenesis of FNMTC. We searched for molecular changes in the FOXE1 gene in the probands from 60 Portuguese families with FNMTC. In this series, we identified nine polymorphisms and one variant (c.743C>G, p.A248G) which was not previously described. This variant, which involved an amino acid residue conserved in evolution, segregated with disease in one family, and was also detected in an apparently unrelated case of sporadic NMTC. Functional studies were performed using rat normal thyroid cells (PCCL3) clones and human papillary thyroid carcinoma cell line (TPC-1) pools, expressing the wild type and mutant (p.A248G) forms of FOXE1. In these experiments, we observed that the p.A248G variant promoted cell proliferation and migration, suggesting that it may be involved in thyroid tumorigenesis. Additionally, somatic p.V600E BRAF mutations were also detected in the thyroid tumors of two members of the family carrying the p.A248G variant. This study represents the first evidence of involvement of a germline FOXE1 rare variant in FNMTC etiology and suggests that mutations in MAPK pathway-related genes may contribute to tumor development in these familial cases.

Thyroid transcription factors in development, differentiation and disease

Identification of the thyroid transcription factors (TTFs), NKX2-1, FOXE1, PAX8 and HHEX, has considerably advanced our understanding of thyroid development, congenital thyroid disorders and thyroid cancer. The TTFs are fundamental to proper formation of the thyroid gland and for maintaining the functional differentiated state of the adult thyroid; however, they are not individually required for precursor cell commitment to a thyroid fate. Although knowledge of the mechanisms involved in thyroid development has increased, the full complement of genes involved in thyroid gland specification and the signals that trigger expression of the genes that encode the TTFs remain unknown. The mechanisms involved in thyroid organogenesis and differentiation have provided clues to identifying the genes that are involved in human congenital thyroid disorders and thyroid cancer. Mutations in the genes that encode the TTFs, as well as polymorphisms and epigenetic modifications, have been associated with thyroid pathologies. Here, we summarize the roles of the TTFs in thyroid development and the mechanisms by which they regulate expression of the genes involved in thyroid differentiation. We also address the implications of mutations in TTFs in thyroid diseases and in diseases not related to the thyroid gland.

Reduced NKX2.1 expression predicts poor prognosis of gastric carcinoma

Thyroid transcription factor-1 (NKX2.1/TITF-1) is a member of the thyroid tissue-specific transcription factor family that has been proven to be closely associated with many human diseases. Recently, it was reported that NKX2.1 expression is lost or reduced in some human cancers such as lung cancer and thyroid cancer. However, there was insufficient data to suggest that NKX2.1 functionality could be used as a prognostic factor. Therefore, this study aims to investigate NKX2.1 expression and its prognostic significance in primary gastric carcinoma. Then, we attempted to investigate if NKX2.1 expression was related to the clinicopathological characteristics and prognosis of gastric carcinoma (GC)patients. The expression levels of NKX2.1 were analyzed in tissue samples from 205 gastric carcinoma patients by real-time quantitative PCR (qRT-PCR), Western blotting, and immunohistochemical staining(IHC). Our qRT-PCR results showed that the expression of NKX2.1 mRNA was reduced in tumor tissue samples compared with that in matched adjacent non-tumor tissue samples (P < 0.001); this finding was confirmed by Western blot analysis (P < 0.001). Our immunohistochemical staining data indicated that NKX2.1 expression was significantly decreased in 87 of 205 (42.4%) gastric carcinoma cases. Kaplan-Meier survival curves revealed that the decreased expression of NKX2.1 was significantly associated with poor prognosis in gastric carcinoma patients (P < 0.001). Multivariate Cox analysis identified NKX2.1 expression as an independent prognostic factor for overall survival (P = 0.005). Furthermore, the functions of Nkx2.1 were analyzed with respect to the proliferation, migration, and invasion of GC cell lines. Our data suggest that NKX2.1 may function as a tumor suppressor in primary gastric carcinoma and that its reduced expression independently predicts an unsatisfactory prognosis in gastric carcinoma patients.

Associations between rs965513/rs944289 and papillary thyroid carcinoma risk: a meta-analysis

Single-nucleotide polymorphisms of rs965513 (9q22.33) and rs944289 (14q13.3) may be involved in the pathogenesis of papillary thyroid carcinoma (PTC). But, relevant genetic studies reported different results. The aim of this meta-analysis was to derive a more precise assessment of the association of rs965513/rs944289 polymorphism with PTC risk. Relevant studies were identified using PubMed, ISI Web of knowledge, Medline, Embase, Google Scholar Search database, SinoMed (Chinese), CNKI (Chinese), GeNii (Japanese) and ICHUSHI (Japanese) (update to December, 2013). A total of eight case-control studies with 52,363 subjects for rs965513 and 51,120 subjects for rs944289 were included. The results showed significant associations of rs965513/rs944289 with PTC risk existed in overall population (for rs965513, A vs. G: OR 1.71 (1.56-1.86); for rs944289, T vs. C: OR 1.29 (1.23-1.37)). Subgroup analysis by ethnicity showed that there were significant associations in Asians (for rs965513, A vs. G: OR 1.48 (1.27-1.73); for rs944289, T vs. C: OR 1.35 (1.18-1.55)), in Europeans (for rs965513, A vs. G: OR 1.74 (1.61-1.88); for rs944289, T vs. C: OR 1.24 (1.14-1.34)), and in Americans (for rs965513, A vs. G: OR 2.00 (1.76-2.27); for rs944289, T vs. C: OR 1.29 (1.14-1.47)). In conclusion, Rs965513 [A] and rs944289 [T] are risk factors of PTC. Effect estimate for rs965513 polymorphism is higher in Americans than in Asians.

Gene expression, function, and diversity of Nkx2-4 in the rainbow trout, Oncorhynchus mykiss

Nkx2 homeodomain transcription factors are involved in various developmental processes and cell specification: e.g. in mammals, NKX2-1 is essential for thyroid-specific gene expression and thyroid morphogenesis. Among Nkx2 proteins, information is still very limited for Nkx2-4. In the present study, we have identified three distinct cDNAs encoding Nkx2-4 isoforms (Nkx2-4a, -b, and -c) from the rainbow trout thyroid tissue, and characterized their transcriptional properties. The trout Nkx2-4 proteins were all predicted to conserve three characteristic domains: the tinman-like amino terminal decapeptide, the NK2 homeodomain, and the NK2-specific domain, and also share 75-89% amino acid similarity. It was shown by dual luciferase assay that Nkx2-4a and Nkx2-4b, but not Nkx2-4c, significantly activated transcription from a cotransfected rat thyroglobulin (TG) promoter. An electrophoretic mobility shift assay indicated that all the Nkx2-4 isoforms could bind to the TG promoter, implying that the faint transcriptional activity of Nkx2-4c might result from some critical amino acid substitution(s) outside the homeodomain. RT-PCR analysis revealed similar tissue distribution patterns for Nkx2-4a and Nkx2-4b mRNAs. Both mRNAs were expressed abundantly in the thyroid, and weakly in the testis. On the other hand, Nkx2-4c mRNA was detected in the ovary as well as in the thyroid. The expression sites of Nkx2-4c mRNA were localized, by in situ hybridization histochemistry, to the ovarian granulosa cells and to the thyroid follicular cells. The results suggest that in the rainbow trout, Nkx2-4a and Nkx2-4b might play a major role in TG gene transcription whereas Nkx2-4c might have some functions in the ovary as well as the thyroid.

Molecular cloning and functional characterization of two forms of Pax8 in the rainbow trout, Oncorhynchus mykiss

We have identified two distinct Pax8 (a and b) mRNAs from the thyroid gland of the rainbow trout (Oncorhynchus mykiss), which seemed to be generated by alternative splicing. Both Pax8a and Pax8b proteins were predicted to possess the paired domain, octapeptide, and partial homeodomain, while Pax8b lacked the carboxy-terminal portion due to an insertion in the coding region of the mRNA. RT-PCR analysis showed each of Pax8a and Pax8b mRNAs to be abundantly expressed in the thyroid and kidney. In situ hybridization histochemistry further detected the expression of Pax8 mRNA in the epithelial cells of the thyroid follicles of the adult trout and in the thyroid primordial cells of the embryo. The functional properties of Pax8a and Pax8b were investigated by dual luciferase assay. The transcriptional regulation by the rat thyroid peroxidase (TPO) promoter was found to be increased by Pax8a, but not by Pax8b. Pax8a further showed synergistic transcriptional activity with rat Nkx2-1 for the human TPO upstream region including the enhancer and promoter. On the other hand, Pax8b decreased the synergistic activity of Pax8a and Nkx2-1. Electrophoretic mobility shift assay additionally indicated that not only Pax8a but also Pax8b can bind to the TPO promoter and enhancer, implying that the inhibitory effect of Pax8b might result from the lack of the functional carboxy-terminal portion. Collectively, the results suggest that for the trout thyroid gland, Pax8a may directly increase TPO gene expression in cooperation with Nkx2-1 while Pax8b may work as a non-activating competitor for the TPO transcription.

Are the SNPs of NKX2-1 associated with papillary thyroid carcinoma in the Han population of Northern China?

Papillary thyroid carcinoma (PTC) is one of the most common tumors of the thyroid gland. The common risk factors of PTC include ionizing radiation, positive family history, and thyroid nodular disease. PTC was identified in Europeans by conducting a genome-wide association study, and a strong association signal with PTC was observed in rs944289 and NKX2-1 (located at the 14q13.3 locus), which was probably the genetic risk factor of PTC. This study aimed to examine the association of this gene with PTC in Chinese. A total of 354 patients with PTC and 360 healthy control subjects from the Han population of Northern China were recruited in the study. These individuals were genotyped to determine rs12589672, rs12894724, rs2076751, and rs944289. The association of rs944289 with PTC was obtained (C vs. T, P = 0.027, OR = 1.264, 95% CI = 1.026 - 1.557; and C/C - C/T vs. T/T, P = 0.034, OR = 1.474, 95% CI = 1.028 - 2.112). Conducting a subgroup analysis, we found a marginal difference in the allele frequency distribution of rs944289 (adjusted P = 0.062) between the patients with PTC and multi-nodular goiter and the control subjects. We also observed an interaction (P = 0.029; OR = 2.578, 95% CI = 1.104 - 6.023) between rs944289 and diabetes in patients with PTC. In conclusion, rs944289 was associated with an increased risk of PTC in the Han population of Northern China, but no clear association was observed in either of the tag single nucleotide polymorphisms of NKX2-1.

The complexity of thyroid transcription factor 1 with both pro- and anti-oncogenic activities

After the original identification of thyroid transcription factor 1 (TTF-1 or NKX2-1) biochemical activity as a transcriptional regulator of thyroglobulin in 1989, the bulk of the ensuing research has concentrated on elucidating the roles of NKX2-1 in the development of lung and thyroid tissues. Motivated by its specific expression pattern, pathologists adopted the NKX2-1 immunoreactivity to distinguish pulmonary from nonpulmonary nonthyroid adenocarcinomas. Interestingly, the concept of NKX2-1 as an active participant in lung tumorigenesis did not take hold until 2007. This minireview contrasts the recent advancements of NKX2-1-related observations primarily in the realm of pulmonary malignancies.

The embryonic transcription factor Hlxb9 is a menin interacting partner that controls pancreatic β-cell proliferation and the expression of insulin regulators

The multiple endocrine neoplasia type 1 (MEN1) syndrome is caused by germline mutations in the MEN1 gene encoding menin, with tissue-specific tumors of the parathyroids, anterior pituitary, and enteropancreatic endocrine tissues. Also, 30-40% of sporadic pancreatic endocrine tumors show somatic MEN1 gene inactivation. Although menin is expressed in all cell types of the pancreas, mouse models with loss of menin in either pancreatic α-cells, or β-cells, or total pancreas develop β-cell-specific endocrine tumors (insulinomas). Loss of widely expressed tumor suppressor genes may produce tissue-specific tumors by reactivating one or more embryonic-specific differentiation factors. Therefore, we determined the effect of menin overexpression or knockdown on the expression of β-cell differentiation factors in a mouse β-cell line (MIN6). We show that the β-cell differentiation factor Hlxb9 is posttranscriptionally upregulated upon menin knockdown, and it interacts with menin. Hlxb9 reduces cell proliferation and causes apoptosis in the presence of menin, and it regulates genes that modulate insulin level. Thus, upon menin loss or from other causes, dysregulation of Hlxb9 predicts a possible combined mechanism for β-cell proliferation and insulin production in insulinomas. These observations help to understand how a ubiquitously expressed protein such as menin might control tissue-specific tumorigenesis. Also, our findings identify Hlxb9 as an important factor for β-cell proliferation and insulin regulation.