Genotyping of an Italian papillary thyroid carcinoma cohort revealed high prevalence of BRAF mutations, absence of RAS mutations and allowed the detection of a new mutation of BRAF oncoprotein (BRAF(V599lns))

Thyroid cancer under the scope of emerging technologies

The vast majority of thyroid cancers originate from follicular cells. We outline outstanding issues at each step along the path of cancer patient care, from prevention to post-treatment follow-up and highlight how emerging technologies will help address them in the coming years. Three directions will dominate the coming technological landscape. Genomics will reveal tumoral evolutionary history and shed light on how these cancers arise from the normal epithelium and the genomics alteration driving their progression. Transcriptomics will gain cellular and spatial resolution providing a full account of intra-tumor heterogeneity and opening a window on the microenvironment supporting thyroid tumor growth. Artificial intelligence will set morphological analysis on an objective quantitative ground laying the foundations of a systematic thyroid tumor classification system. It will also integrate into unified representations the molecular and morphological perspectives on thyroid cancer.

PRKAR1A and Thyroid Tumors

Simple Summary

In 2021 it is estimated that there will be 44,280 new cases of thyroid cancer in the United States and the incidence rate is higher in women than in men by almost 3 times. Well-differentiated thyroid cancer is the most common subtype of thyroid cancer and includes follicular (FTC) and papillary (PTC) carcinomas. Over the last decade, researchers have been able to better understand the molecular mechanisms involved in thyroid carcinogenesis, identifying genes including but not limited to RAS, BRAF, PAX8/PPARγ chromosomal rearrangements and others, as well as several tumor genes involved in major signaling pathways regulating cell cycle, differentiation, growth, or proliferation. Patients with Carney complex (CNC) have increased incidence of thyroid tumors, including cancer, yet little is known about this association. CNC is a familial multiple neoplasia and lentiginosis syndrome cause by inactivating mutations in the PRKAR1A gene which encodes the regulatory subunit type 1α of protein kinase A. This work summarizes what we know today about PRKAR1A defects in humans and mice and their role in thyroid tumor development, as the first such review on this issue.

Abstract

Thyroid cancer is the most common type of endocrine malignancy and the incidence is rapidly increasing. Follicular (FTC) and papillary thyroid (PTC) carcinomas comprise the well-differentiated subtype and they are the two most common thyroid carcinomas. Multiple molecular genetic and epigenetic alterations have been identified in various types of thyroid tumors over the years. Point mutations in BRAF, RAS as well as RET/PTC and PAX8/PPARγ chromosomal rearrangements are common. Thyroid cancer, including both FTC and PTC, has been observed in patients with Carney Complex (CNC), a syndrome that is inherited in an autosomal dominant manner and predisposes to various tumors. CNC is caused by inactivating mutations in the tumor-suppressor gene encoding the cyclic AMP (cAMP)-dependent protein kinase A (PKA) type 1α regulatory subunit (PRKAR1A) mapped in chromosome 17 (17q22–24). Growth of the thyroid is driven by the TSH/cAMP/PKA signaling pathway and it has been shown in mouse models that PKA activation through genetic ablation of the regulatory subunit Prkar1a can cause FTC. In this review, we provide an overview of the molecular mechanisms contributing to thyroid tumorigenesis associated with inactivation of the RRKAR1A gene.

Computational modeling reveals MAP3K8 as mediator of resistance to vemurafenib in thyroid cancer stem cells

MOTIVATION

Val600Glu (V600E) mutation is the most common BRAF mutation detected in thyroid cancer. Hence, recent research efforts have been performed trying to explore several inhibitors of the V600E mutation-containing BRAF kinase as potential therapeutic options in thyroid cancer refractory to standard interventions. Among them, vemurafenib is a selective BRAF inhibitor approved by Food and Drug Administration for clinical practice. Unfortunately, vemurafenib often displays limited efficacy in poorly differentiated and anaplastic thyroid carcinomas probably because of intrinsic and/or acquired resistance mechanisms. In this view, cancer stem cells (CSCs) may represent a possible mechanism of resistance to vemurafenib, due to their self-renewal and chemo resistance properties.

RESULTS

We present a computational framework to suggest new potential targets to overcome drug resistance. It has been validated with an in vitro model based upon a spheroid-forming method able to isolate thyroid CSCs that may mimic resistance to vemurafenib. Indeed, vemurafenib did not inhibit cell proliferation of BRAF V600E thyroid CSCs, but rather stimulated cell proliferation along with a paradoxical over-activation of ERK and AKT pathways. The computational model identified a fundamental role of mitogen-activated protein kinase 8 (MAP3K8), a serine/threonine kinase expressed in thyroid CSCs, in mediating this drug resistance. To confirm model prediction, we set a suitable in vitro experiment revealing that the treatment with MAP3K8 inhibitor restored the effect of vemurafenib in terms of both DNA fragmentation and poly (ADP-ribose) polymerase cleavage (apoptosis) in thyroid CSCs. Moreover, MAP3K8 expression levels may be a useful marker to predict the response to vemurafenib.

AVAILABILITY AND IMPLEMENTATION

The model is available in GitHub repository visiting the following URL: https://github.com/francescopappalardo/MAP3K8-Thyroid-Spheres-V-3.0.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Low Prevalence of TERT Promoter, BRAF and RAS Mutations in Papillary Thyroid Cancer in the Greek Population

Thyroid cancer is a common endocrine malignancy and displays a variety of histological patterns ranging from adenoma to malignant tumors. Molecular diagnostics have given significant insights into the genetic basis of thyroid tumorigenesis, known to be linked with signaling pathways affected by oxidative stress. We report for the first time a genotype study of TERT promoter combined with BRAF and RAS mutations in Papillary Thyroid Cancer (PTC) cases in the Greek population. Polymerase Chain Reaction and sequencing were used to identify TERT promoter (C228T, C250T, CC243-243TT) mutations, the BRAF (T1799A) mutation and mutations in codons 12, 13, 61 of the HRAS, KRAS and NRAS genes. The most common C228T TERT promoter mutation was identified in 2 PTC cases co-existing with the BRAF mutation. The BRAF T1799A mutation was detected in 10 PTC cases, while two different NRAS mutations in codon 61 (C181A and A182G) were found in 2 PTC cases. These mutations occur in a mutually exclusive manner. Our results indicate that despite the low frequencies, the study of the specific mutations should be encouraged because they are indicative of aggressive forms of thyroid cancer of the papillary histotype in this patient cohort, thus providing insights towards their therapeutic management.

Mutational Profile of Papillary Thyroid Carcinoma in an Endemic Goiter Region of North India

INTRODUCTION

Mitogen activated protein kinase (MAPK) pathway is regularly altered in papillary thyroid carcinomas (PTCs). Serine/threonine-protein kinase B-Raf (BRAF) V600E mutations were observed very frequently in PTC along with less frequent rat sarcoma (RAS) and rearranged during transfection (RET) gene, also known as RET/PTC translocation. The present study aimed to analyze the mutational profile of PTCs from an endemic Goiter area of North India.

METHODOLOGY

Tissues from 109 PTC patients were used to isolate DNA and RNA. BRAF V600E was detected by restriction fragment length polymorphism-polymerase chain reaction (PCR). RAS mutations were screened by using Sanger's sequencing method. RET/PTC rearrangements were analyzed by real-time PCR.

RESULTS

BRAF V600E mutation was detected in 51.38% (56/109) of PTCs, whereas RAS mutations were less frequent. No RET/PTC rearrangements were observed. BRAF V600E was found to be associated with the aggressive clinicopathological features such as lymph node metastasis, distant metastasis, higher tumor-node-metastasis stages, and high-risk groups.

CONCLUSION

The prevalence of BRAF V600E is high in patients from Indian Subcontinent and found to be associated with aggressive features of PTC. Concomitant mutations of BRAF V600E and RAS mutations impart more aggressiveness to PTCs.

BRAFV600E and RET/PTC Promote Proliferation and Migration of Papillary Thyroid Carcinoma Cells In Vitro by Regulating Nuclear Factor-κB

Background

Papillary thyroid carcinoma (PTC) is associated with mutations of BRAF^V600E and RET/PTC and high levels of expression of nuclear factor-κB (NF-κB). However, few studies have focused on the association between NF-κB expression and mutations in BRAF^V600E and RET/PTC, especially regarding PTC cell proliferation and migration. The aim of this in vitro study was to investigate the effect of BRAF^V600E or RET/PTC on NF-κB expression, cell proliferation and cell migration in four established PTC cell lines.

Material/Methods

Four cell lines included TPC-1 (BRAF^WT/WT), BCPAP (BRAF^V600E/V600E), PCCL3, and PTC3-5 (RET/PTC), were grown in culture in vitro with or without suppression of NF-κB using pyrrolidine dithiocarbamate (PDTC), and cell proliferation, and cell migration were evaluated.

Results

Expression of the BRAF gene was increased in the BCPAP cell line when compared with the TPC-1 cells. Expression of the RET gene was increased in the PTC3-5 cell line when compared with the PCCL3 cells. In the BCPAP and PTC3-5 cell lines, the relative expression of NF-κB protein, including phosphorylated p100/52, phosphorylated p65, phosphorylated IKKα/β, phosphorylated IκBα, and p65 nuclear translocation were increased compared with the TPC-1 and PCCL3 cells. Proliferation and migration of BCPAP and PTC3-5 cells were increased compared with the TPC-1 and PCCL3 cells. Suppression of NF-κB reduced NF-κB protein expression and inhibited the proliferation of cells in the TPC-1, BCPAP, PCCL3 and PTC3-5 cell lines, and migration of the BCPAP and PTC3-5 cells.

Conclusions

BRAF^V600E and RET/PTC and the expression of NF-κB promote the proliferation and migration of papillary thyroid carcinoma cells in vitro.

Comparative analysis of diagnostic performance, feasibility and cost of different test-methods for thyroid nodules with indeterminate cytology

Since it is impossible to recognize malignancy at fine needle aspiration (FNA) cytology in indeterminate thyroid nodules, surgery is recommended for all of them. However, cancer rate at final histology is <30%. Many different test-methods have been proposed to increase diagnostic accuracy in such lesions, including Galectin-3-ICC (GAL-3-ICC), BRAF mutation analysis (BRAF), Gene Expression Classifier (GEC) alone and GEC+BRAF, mutation/fusion (M/F) panel, alone, M/F panel+miRNA GEC, and M/F panel by next generation sequencing (NGS), FDG-PET/CT, MIBI-Scan and TSHR mRNA blood assay.We performed systematic reviews and meta-analyses to compare their features, feasibility, diagnostic performance and cost. GEC, GEC+BRAF, M/F panel+miRNA GEC and M/F panel by NGS were the best in ruling-out malignancy (sensitivity = 90%, 89%, 89% and 90% respectively). BRAF and M/F panel alone and by NGS were the best in ruling-in malignancy (specificity = 100%, 93% and 93%). The M/F by NGS showed the highest accuracy (92%) and BRAF the highest diagnostic odds ratio (DOR) (247). GAL-3-ICC performed well as rule-out (sensitivity = 83%) and rule-in test (specificity = 85%), with good accuracy (84%) and high DOR (27) and is one of the cheapest (113 USD) and easiest one to be performed in different clinical settings.In conclusion, the more accurate molecular-based test-methods are still expensive and restricted to few, highly specialized and centralized laboratories. GAL-3-ICC, although limited by some false negatives, represents the most suitable screening test-method to be applied on a large-scale basis in the diagnostic algorithm of indeterminate thyroid lesions.

Expression Profiling of a Human Thyroid Cell Line Stably Expressing the BRAFV600E Mutation

BACKGROUND/AIM

The BRAF^V600E mutation acts as an initiator of cancer development in papillary thyroid carcinoma (PTC). Gene expression changes caused by the BRAF^V600E mutation may have an important role in thyroid cancer development.

MATERIALS AND METHODS

To study genomic alterations caused by the BRAF^V600E mutation, we made human thyroid cell lines that harbor the wild-type BRAF gene (Nthy/WT) and the V600E mutant-type BRAF gene (Nthy/V600E).

RESULTS

Flow cytometry and western blotting showed stable transfection of the BRAF gene. In functional experiments, Nthy/V600E showed increased anchorage-independent growth and invasion through Matrigel, compared to Nthy/WT. Microarray analysis revealed that 2,441 genes were up-regulated in Nthy/V600E compared to Nthy/WT. Gene ontology analysis showed that the up-regulated genes were associated with cell adhesion, migration, and the ERK and MAPK cascade, and pathway analysis showed enrichment in cancer-related pathways.

CONCLUSION

Our Nthy/WT and Nthy/V600E cell line pair could be a suitable model to study the molecular characteristics of BRAF^V600E PTC.

RAS Mutations, and RET/PTC and PAX8/PPAR-gamma Chromosomal Rearrangements Are Also Prevalent in Benign Thyroid Lesions: Implications Thereof and A Systematic Review

BACKGROUND

Molecular markers associated with thyroid malignancy are increasingly being used as differential diagnostic tools for thyroid nodules. However, little has been reported recently regarding the prevalence of these markers in benign lesions. The literature was systematically reviewed to examine studies that reported on the prevalence of these markers in benign thyroid lesions.

METHODS

Appropriate studies published between January 1, 2000, and April 30, 2015, and cataloged in PubMed, Embase, Cochrane, Scopus, and Web of Science databases were searched for by combining different keywords for "thyroid tumor" with both general and specific keywords for "molecular marker" by using "AND" as the Boolean operator. All studies meeting criteria that reported the prevalence of RAS mutations, and RET/PTC and PAX8/PPAR-gamma chromosomal rearrangements in benign thyroid lesions were included for study.

RESULTS

A total of 64 articles (including 8162 patients, of whom 42.5% had benign lesions) that met all the study criteria were systematically reviewed and abstracted. Among 35 studies examining RAS mutations, the reported prevalence of RAS mutation in benign lesions ranged from 0% to 48%. In 38 studies examining RET/PTC rearrangements, the prevalence in benign lesions ranged from 0% to 68%. PAX8/PPAR-gamma rearrangements were examined in 27 studies, with the prevalence in benign lesions ranging from 0% to 55%.

CONCLUSION

The presence of these biomarkers and the tremendous variation in reports of their prevalence in benign lesions suggests the need for caution when including these markers in diagnostic decisions. Further understanding of the importance of these markers, as well as newly discovered markers of thyroid malignancy, may be required in order to avoid overtreatment of patients with benign thyroid tumors.

Novel BRAFI599Ins Mutation Identified in a Follicular Variant of a Papillary Thyroid Carcinoma: A Molecular Modeling Approach

OBJECTIVE

BRAF mutations are the most common genetic alteration found in papillary thyroid carcinoma (PTC). Approximately, 90% correspond to BRAFV600E, although other less common BRAF mutations have been described. The aim of this study was to describe a new mutation on BRAF gene discovered on the previous thyroid cytology of a patient diagnosed with a follicular variant of PTC (FV-PTC).

METHODS

The mutation was identified by independent cloning of the 2 alleles and direct sequencing in the previous cytology and tumor tissue samples from a patient diagnosed with FV-PTC. To elucidate the effect of the mutation on the structure and hence on the activating mechanism of the protein, the structures of BRAFI599Ins, BRAFT599Ins, BRAFV599Ins and BRAFV600E were modeled by using the reconstructed wild-type BRAF (BRAFWT) crystal structure.

RESULTS

The novel mutation in BRAF consisted in the in-frame insertion of 3 nucleotides (TAA) after nucleotide 1795, resulting in the incorporation of an extra isoleucine residue at position 599 (BRAFI599Ins) of the protein. The structural comparison of BRAFI599Ins, BRAFT599Ins, BRAFV599Ins with BRAFWT, and BRAFV600E models revealed that the overall shape of the kinase was conserved in the protein produced by this novel mutation, except for the displacement of the activation loop (A-loop), as a direct consequence of the increase in loop size, and the exposition of 1 of the 2 residues involved in BRAF activation (T599), probably facilitating its phosphorylation.

CONCLUSION

BRAFI599Ins mutation constitutes a new BRAF mutation affecting the length of the A-loop, which most likely facilitates BRAF activation by altering the A-loop conformation.

The management of thyroid nodules and cancer in the molecular era

The incidence of thyroid cancer is increasing worldwide. Current standards in the diagnosis and management of thyroid cancer are limited by the uncertainty of fine-needle aspiration samples that are indeterminate in nature. Molecular markers have the potential to improve the accuracy of thyroid fine-needle aspiration and to aid the physician in giving a more accurate diagnosis and prognosis. This paper summarizes the various molecular markers currently available.

Combined papillary and mucoepidermoid carcinoma of the thyroid gland: a possible collision tumor diagnosed on fine-needle cytology. Report of a case with immunocytochemical and molecular correlations

Fine-needle cytology (FNC) is frequently used to diagnose thyroid nodules discovered by palpation or imaging studies. Molecular tests on FNC material may increase its diagnostic accuracy. We report a case of a classic papillary thyroid carcinoma combined with a mucoepidermoid carcinoma correctly identified on FNC. The papillary component had a classic immunophenotype (CK19+, TTF1+), while the mucoepidermoid one was only focally CK19+. Point mutations (BRAF and RAS) and rearrangements (RET/PTC) of the papillary component have been also investigated on FNC samples, with resulting concurrent rearrangements of RET/PTC1 and RET/PTC3, but no point mutations. The histogenesis of combined papillary and mucoepidermoid carcinoma of the thyroid still remains partly unsettled, and further genomic studies are needed to shed some more light on this peculiar neoplasm.

Universal BRAF State Detection by the Pyrosequencing®-Based U-BRAF(V⁶⁰⁰) Assay

Malignant melanoma is a highly aggressive type of malignancy with considerable metastatic potential and frequent resistance to cytotoxic agents. BRAF mutant protein was recently recognized as therapeutic target in metastatic melanoma.We present the newly developed U-BRAF(V600) approach (Patent No. 12153477.0-1404)-a universal Pyrosequencing(®)-based assay for mutation detection within the activation segment in exon 15 of human BRAF. We identified five different BRAF mutations in a single assay analyzing 75 different formalin-fixed paraffin-embedded samples of cutaneous melanoma metastases from 29 patients. All mutant variants were quantitatively detectable by the newly developed U-BRAF(V600) assay. These results were confirmed by ultra-deep sequencing. In contrast to all other BRAF state detection methods, the U-BRAF(V600) assay is capable of automated quantitative identification of at least 36 previously published BRAF mutations. Under the precaution of a minimum of 5 % mutated cells in a background of wild-type cells, the U-BRAF(V600) assay design completely excludes false-negative wild-type results. The corresponding algorithm for classification of BRAF-mutated variants is provided in this chapter together with a detailed step-by-step protocol for the Pyrosequencing reaction.The single-reaction format and automation of data analysis make our approach suitable for the assessment of large clinical cohorts. Therefore, we suggest U-BRAF(V600) assay as a powerful sequencing-based diagnostic tool to automatically identify BRAF status.

Low VHL mRNA expression is associated with more aggressive tumor features of papillary thyroid carcinoma

Alterations of the von Hippel–Lindau (VHL) tumor suppressor gene can cause different hereditary tumors associated with VHL syndrome, but the potential role of the VHL gene in papillary thyroid carcinoma (PTC) has not been characterized. This study set out to investigate the relationship of VHL expression level with clinicopathological features of PTC in an ethnically and geographically homogenous group of 264 patients from Serbia, for the first time. Multivariate logistic regression analysis showed a strong correlation between low level of VHL expression and advanced clinical stage (OR = 5.78, 95% CI 3.17–10.53, P<0.0001), classical papillary morphology of the tumor (OR = 2.92, 95% CI 1.33–6.44, P = 0.008) and multifocality (OR = 1.96, 95% CI 1.06–3.62, P = 0.031). In disease-free survival analysis, low VHL expression had marginal significance (P = 0.0502 by the log-rank test) but did not appear to be an independent predictor of the risk for chance of faster recurrence in a proportion hazards model. No somatic mutations or evidence of VHL downregulation via promoter hypermethylation in PTC were found. The results indicate that the decrease of VHL expression associates with tumor progression but the mechanism of downregulation remains to be elucidated.

A 23-year-old female with a mixed germ cell tumor of the pituitary infundibulum: the challenge of differentiating neoplasm from lymphocytic infundibuloneurohypophysitis-a case report and literature review

The pathologic spectrum of diseases that infiltrate the pituitary infundibulum includes a broad variety of clinical entities. There are significant differences in the prevalence of these etiologies depending on the age of presentation. Lymphocytic infundibuloneurohypophysitis (LINH) predominates over other causes of infundibular disease in adults over age 21. Differentiating LINH from other causes of infundibular disease can be difficult because the various etiologies often have similar clinical presentations and radiologic imaging characteristics. We report the first case in an adult of a mixed germ cell tumor comprised of germinoma and embryonal cell carcinoma infiltrating the pituitary infundibulum. In our case, a 23-year-old female was initially misdiagnosed as having LINH. She presented with panhypopituitarism and diabetes insipidus, which is the most common initial presentation in both entities. The two diagnoses are difficult to distinguish based on MRI imaging, CSF findings, and histopathological examination. Our case demonstrates the need for close follow-up of patients with isolated lesions of the pituitary infundibulum and reinforces the need for biopsy of an infundibular lesion when progression of disease is demonstrated. In our case, biopsy with comprehensive immunohistochemical staining was the sole means of making a definitive diagnosis.

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.

Immune response in thyroid cancer: widening the boundaries

The association between thyroid cancer and thyroid inflammation has been repeatedly reported and highly debated in the literature. In fact, both molecular and epidemiological data suggest that these diseases are closely related and this association reinforces that the immune system is important for thyroid cancer progression. Innate immunity is the first line of defensive response. Unlike innate immune responses, adaptive responses are highly specific to the particular antigen that induced them. Both branches of the immune system may interact in antitumor immune response. Major effector cells of the immune system that directly target thyroid cancer cells include dendritic cells, macrophages, polymorphonuclear leukocytes, mast cells, and lymphocytes. A mixture of immune cells may infiltrate thyroid cancer microenvironment and the balance of protumor and antitumor activity of these cells may be associated with prognosis. Herein, we describe some evidences that immune response may be important for thyroid cancer progression and may help us identify more aggressive tumors, sparing the vast majority of patients from costly unnecessary invasive procedures. The future trend in thyroid cancer is an individualized therapy.

Differentiated thyroid tumors: surgical indications

Thyroid gland tumors represent 1% of malignant tumors. In Italy their incidence is in constant growth. The aggressiveness depends on the histological type. The relative non-aggressive grade of different forms of tumors is the basis for discussing the treatment of choice: total thyroidectomy vs lobectomy with or without lymphadenectomy of the sixth level in the absence of metastasis. Authors report about their experience, and they advocate, given the high percentage of multicentric forms, total thyroidectomy as treatment of choice.

Genetic mutations, molecular markers and future directions in research

Recent molecular studies have described a number of abnormalities associated with the pathogenesis of thyroid carcinoma. These distinct molecular events are often associated with specific stages of tumor development and may serve as prognostic factors and therapeutic targets. A better understanding of the mechanisms involved in thyroid cancer pathogenesis, will hopefully help translate these discoveries to improved patient care.

Automated universal BRAF state detection within the activation segment in skin metastases by pyrosequencing-based assay U-BRAF(V600)

Malignant melanoma is a highly-aggressive type of malignancy with considerable metastatic potential and frequent resistance to cytotoxic agents. BRAF mutant protein was recently recognized as therapeutic target in metastatic melanoma. We present a newly-developed U-BRAF^V600 approach – a universal pyrosequencing-based assay for mutation detection within activation segment in exon 15 of human braf. We identified 5 different BRAF mutations in a single assay analyzing 75 different formalin-fixed paraffin-embedded (FFPE) samples of cutaneous melanoma metastases from 29 patients. We found BRAF mutations in 21 of 29 metastases. All mutant variants were quantitatively detectable by the newly-developed U-BRAF^V600 assay. These results were confirmed by ultra-deep-sequencing validation (^∼60,000-fold coverage). In contrast to all other BRAF state detection methods, the U-BRAF^V600 assay is capable of automated quantitative identification of at least 36 previously-published BRAF mutations. Under the precaution of a minimum of 3% mutated cells in front of a background of wild type cells, U-BRAFV600 assay design completely excludes false wild-type results. The corresponding algorithm for classification of BRAF-mutated variants is provided. The single-reaction assay and data analysis automation makes our approach suitable for the assessment of large clinical sample sizes. Therefore, we suggest U-BRAF^V600 assay as a most powerful sequencing-based diagnostic tool to automatically identify BRAF state as a prerequisite to targeted therapy.

Signaling pathways in follicular cell-derived thyroid carcinomas (review)

Thyroid carcinoma is the most common malignant endocrine neoplasia. Differentiated thyroid carcinomas (DTCs) represent more than 90% of all thyroid carcinomas and comprise the papillary and follicular thyroid carcinoma subtypes. Anaplastic thyroid carcinomas correspond to less than 1% of all thyroid tumors and can arise de novo or by dedifferentiation of a differentiated tumor. The etiology of DTCs is not fully understood. Several genetic events have been implicated in thyroid tumorigenesis. Point mutations in the BRAF or RAS genes or rearranged in transformation (RET)/papillary thyroid carcinoma (PTC) gene rearrangements are observed in approximately 70% of papillary cancer cases. Follicular carcinomas commonly harbor RAS mutations and paired box gene 8 (PAX8)-peroxisome proliferator-activated receptor γ (PPARγ) rearrangements. Anaplastic carcinomas may have a wide set of genetic alterations, that include gene effectors in the mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K) and/or β-catenin signaling pathways. These distinct genetic alterations constitutively activate the MAPK, PI3K and β-catenin signaling pathways, which have been implicated in thyroid cancer development and progression. In this context, the evaluation of specific genes, as well as the knowledge of their effects on thyroid carcinogenesis may provide important information on disease presentation, prognosis and therapy, through the development of specific tyrosine kinase targets. In this review, we aimed to present an updated and comprehensive review of the recent advances in the understanding of the genetic basis of follicular cell-derived thyroid carcinomas, as well as the molecular mechanisms involved in tumor development and progression.

Comparison of the diagnostic accuracy of combined elastosonography and BRAF analysis vs cytology and ultrasonography for thyroid nodule suspected of malignancy

OBJECTIVE

Diagnosing thyroid nodules preoperatively using traditional diagnostic tools - ultrasonography (US) and cytology - still carries a considerable degree of uncertainty, and surgery is recommended for a far from negligible number of patients simply for diagnostic purposes. Thyroid elastosonography (USE) and BRAF analysis have recently proved useful in detecting thyroid malignancies. The aim of this study is to establish whether combining USE and BRAF testing ameliorates preoperative diagnosis of thyroid nodule candidates for intervention by conventional approaches, thereby avoiding the need for diagnostic surgical procedures.

DESIGN AND PATIENTS

We retrospectively analysed the files of 155 consecutive patients with 164 nodules, all assessed by ultrasonography, cytology, USE and BRAF testing, who underwent thyroid surgery.

RESULTS

Of the 164 nodules, 74 (45%) were benign and 90 (55%) were malignant at final histology. Combining ultrasonography and cytology identified 21 (13%) as benign, 93 (57%) as malignant or probably malignant and 50 (30%) as 'suspended' (when the combined test was not able to classify the node as benign or malignant) with a 99% sensitivity, 28% specificity, 63% PPV, 95% NPV and 67% accuracy. Combining USE and BRAF testing indicated that 59 (36%) were benign, 74 (45%) were malignant and 31 (19%) were in a 'suspended' category, with a 95% sensitivity, 74% specificity, 82% PPV, 93% NPV and 86% accuracy.

CONCLUSIONS

In assessing thyroid nodules suspected of malignancy, the combined analysis of USE and BRAF is equally sensitive and more specific than conventional procedures, achieving more accurate preoperative diagnoses than US and cytology combined. USE and BRAF analysis for thyroid nodule evaluation might reduce the number of unnecessary surgical procedures.

Cribriform adenocarcinoma of minor salivary glands may express galectin-3, cytokeratin 19, and HBME-1 and contains polymorphisms of RET and H-RAS proto-oncogenes

The aim of the study was to further elucidate the immunohistochemical and genetic characteristics of cribriform adenocarcinoma of minor salivary glands (CAMSG). The study comprised five CAMSG from two males and three females, aged 21-72 years. Four tumors were localized at the base of tongue and one in the floor of mouth. At the time of diagnosis, four tumors had metastasised to regional lymph nodes. After tumor resection, two patients were treated by radiotherapy and one by chemoradiotherapy. During the follow-up (median 14 months), two patients developed lymph node metastasis. Microscopically, all tumors showed cribriform, papillary, follicular, and microcystic growth patterns. The tumor cells displayed vesicular nuclei with intranuclear grooves. Immunohistochemically, all tumors showed expression of cytokeratin (CK) 7, CK8, CK18, vimentin, smooth muscle actin, calponin, S-100 protein, and p16 protein. In addition, we observed expression of galectin-3, CK19, and HBME-1, but not of thyroglobulin and TTF-1. No mutations of RET, BRAF, K-RAS, H-RAS, and N-RAS proto-oncogenes were detected. However, in RET proto-oncogene, we found polymorphisms Gly691Ser (exon 11) and Ser904Ser (exon 15) in one case, p.Leu769Leu (exon 13) in one case, and variant p.IVS14-24 G/A of intron 14 in two cases, and in H-RAS proto-oncogene we found polymorphism 81 T-C (exon 1) in three cases. Thyroglobulin and TTF-1 are the only useful markers in the differential diagnosis between CAMSG and papillary thyroid carcinoma as both tumors may express galectin-3, CK19, and HBME-1. The RET, H-RAS, and N-RAS proto-oncoogenes are not mutated in CAMSG.

BRAF mutations in thyroid tumors from an ethnically diverse group

BACKGROUND

The molecular etiology of thyroid carcinoma (TC) and other thyroid diseases which may present malignant precursor lesions is not fully explored yet. The purpose of this study was to estimate frequency, type and clinicopathological value of BRAF exon 15 mutations in different types of cancerous and non-cancerous thyroid lesions originating in an ethnically diverse population.

METHODS

BRAF exon 15 was sequenced in 381 cases of thyroid lesions including Hashimoto´s thyroiditis, nodular goiters, hyperplastic nodules, follicular adenomas (FA), papillary TC (PTC), follicular variant PTC (FVPTC), microcarcinomas of PTC (micro PTC; tumor size ≤ 1 cm), follicular TC (FTC), and non-well differentiated TC (non-WDTC).

RESULTS

We identified BRAF mutations in one of 69 FA, 72 of 115 (63%) PTC, seven of 42 (17%) FVPTC, 10 of 56 (18%) micro PTC, one of 17 (6%) FTC, and one of eight (13%) non-WDTC. Most of the cases showed the common V600E mutation. One case each of PTC, FVPTC, and FTC harbored a K601E mutation. A novel BRAF mutation was identified in a FA leading to deletion of threonine at codon 599 (p.T599del). A rare 3-base pair insertion was detected in a stage III PTC resulting in duplication of threonine at codon 599 (p.T599dup). Patients with PTC harboring no BRAF mutation (BRAFwt) were on average younger than those with a BRAF mutation (BRAFmut) in the PTC (36.6 years vs. 43.8 years). Older age (≥ 45 years) in patients with PTC was significantly associated with tumor size ≥ 4 cm (P = 0.018), vessel invasion (P = 0.004), and distant metastasis (P = 0.001). Lymph node (LN) involvement in PTC significantly correlated with tumor size (P = 0.044), and vessel invasion (P = 0.013). Of notice, taken the whole TC group, family history of thyroid disease positively correlated with capsular invasion (P = 0.025).

CONCLUSIONS

Older age is manifold associated with unfavorable tumor markers in our series. The K601E identified in a PTC, FVPTC, and FTC seems to be more distributed among different histological types of TC than previously thought. The T599del is a yet undescribed mutation and the rare T599dup has not been reported as a mutation in PTC so far.

Mining the proteome: the application of tandem mass spectrometry to endocrine cancer research

Tandem mass spectrometry (MS/MS) permits the detection of femtomolar quantities of protein from a wide variety of tissue sources. As endocrine cancers are frequently aetiologically complex, they are particularly amenable to mass spectrometry. The most widely studied aspect is the search for novel reliable biomarkers that would allow cancers to be diagnosed earlier and distinguished from benign tumours. MS/MS allows for the rapid analysis of blood and urine in addition to tumour tissue, and in this regard it has been applied on research involving thyroid, pancreatic, adrenal and ovarian cancers with varying degrees of success, as well as additional organ sites including breast and lung. The description of an individual cancer proteome potentially allows for personalized management of each patient, avoiding unnecessary therapies and targeting treatments to those which will have the most effect. The application of MS/MS to interaction proteomics is a field that has generated recent novel targets for chemotherapy. However, the technology involved in MS/MS has a number of drawbacks that at present prevent its widespread use in translational cancer research, including a poor reproducibility of results, in part due to the large amount of data generated and the inability to accurately differentiate true from false-positive results. Further, the current cost of running MS/MS restricts the number of times the experiments can be repeated, contributing to the lack of significance and concordance between studies. Despite these problems, however, MS/MS is emerging as a front line tool in endocrine cancer research and it is likely that this will continue over the next decade.

Functional characterization of the novel BRAF complex mutation, BRAF(V600delinsYM) , identified in papillary thyroid carcinoma

An activating mutation in the BRAF gene is the most common genetic alteration in papillary thyroid carcinomas (PTCs). The mutation in PTCs is almost a c.1799T>A transversion, resulting in a p.V600E amino acid substitution (BRAF(V600E) ). Here, we report a novel complex BRAF mutation identified in 4/492 Japanese PTC cases (0.81%). The mutation was comprised of one nucleotide substitution at position 1798, followed by an in-frame insertion of three nucleotides, c.1798delinsTACA in Exon 15, resulting in p.V600delinsYM. In silico three-dimensional protein structure prediction implied altered kinase activity of this mutant. In vitro kinase assay and western blotting revealed that this mutation conferred high kinase activity on the BRAF protein, leading to constitutive activation of the MAPK signaling pathway. The mutation also showed high transforming ability in focus formation assay using NIH3T3 cells. The degree of all the functional characteristics was comparable to that of BRAF(V600E) , and treatment with a BRAF inhibitor Sorafenib was also equally effective in this mutant. These findings suggest that the novel BRAF mutation, BRAF(V600delinsYM) , is a gain-of-function mutation and plays an important role in PTC development.

Pediatric thyroid cancer

Thyroid cancer is an uncommon childhood malignancy that presents primarily in young children or adolescent females and may be related to radiation exposure or genetic predisposition. Gene alterations, such as RET mutation or RET/PTC rearrangement, are not uncommon. Recent studies have lead to an increased understanding of the role of these particular gene alterations in the diagnosis, prognosis, and treatment of thyroid cancer. Surgery remains the mainstay of treatment for thyroid cancer followed by radioactive iodine when appropriate. In patients with MEN2, prophylactic thyroidectomy is recommended, although a delay in the initial diagnosis is common. With early aggressive treatment and long-term follow-up, these patients generally have excellent outcomes. Recent research suggests potential usefulness of novel therapies directed at oncogenic signaling pathways, modulators of growth, angiogenesis inhibitors, immunomodulators, and gene therapy.

Intracellular signal transduction and modification of the tumor microenvironment induced by RET/PTCs in papillary thyroid carcinoma

RET gene rearrangements (RET/PTCs) represent together with BRAF point mutations the two major groups of mutations involved in papillary thyroid carcinoma (PTC) initiation and progression. In this review, we will examine the mechanisms involved in RET/PTC-induced thyroid cell transformation. In detail, we will summarize the data on the molecular mechanisms involved in RET/PTC formation and in its function as a dominant oncogene, on the activated signal transduction pathways and on the induced gene expression modifications. Moreover, we will report on the effects of RET/PTCs on the tumor microenvironment. Finally, a short review of the literature on RET/PTC prognostic significance will be presented.

BRAF, p53 and SOX2 in anaplastic thyroid carcinoma: evidence for multistep carcinogenesis

AIMS

The aim of this study was to genotype a series of papillary thyroid carcinomas (PTCs) and anaplastic thyroid carcinomas (ATCs) for BRAF mutation, and to evaluate p53 and SOX2 expression as factors implicated in tumour progression.

METHODS

The study included 17 PTCs and 14 ATCs. Analysis of the exon 15 of BRAF was based on direct sequencing. Immunohistochemistry was used to evaluate p53 and SOX2 expression.

RESULTS

V600E (c.1799T>A) mutation was observed in 53% (9/17) of PTCs. Two cases of ATCs (2/14; 14%), both with PTC component, harboured BRAF mutation: the classical V600E mutation and an undocumented duplication of codon 599 (c.1795_1797dup; p.Thr599dup). These mutations were present in ATC as well as PTC tumour cells. Overexpression of p53 and SOX2 was depicted respectively in 64% (9/14) and 29% (4/14) of ATCs, and absent in PTCs.

CONCLUSION

We confirm that V600E mutation is a frequent and specific event in PTC. BRAF-mutated ATCs are associated with a PTC component displaying the same mutation. We describe a new mutation of BRAF, T599dup, in a case of ATC with tall cell PTC component. Moreover, progression from PTC to ATC could be favoured by further TP53 mutation and SOX2 expression.

Poorer prognosis and higher prevalence of BRAF (V600E) mutation in synchronous bilateral papillary thyroid carcinoma

BACKGROUND

The clinical significance of synchronous bilateral papillary thyroid carcinoma (SBiPTC) has not been fully defined, and the prevalence of BRAF (V600E) mutation in SBiPTC remains unknown. The purpose of this study is to compare the clinical outcomes and BRAF (V600E) mutation incidence of SBiPTC patients with those of unilateral papillary thyroid carcinoma (UiPTC) patients.

METHODS

From 1997 to 2008, a total of 903 patients with papillary thyroid cancer were treated at a single institution. Of 891 studied patients, 177 (19.9%) had SBiPTC and 714 had UiPTC. SBiPTC was defined as cancer diagnosed in both thyroid lobes at the same time or within a period of 3 months. The mean follow-up time was 6 years, ranging from 2.5 to 13.5 years. Rates of disease-free survival (DFS) and overall survival (OS) were calculated and compared. BRAF (V600E) mutation was determined by polymerase chain reaction (PCR) amplification and DNA sequencing.

RESULTS

Compared with UiPTC patients, patients with SBiPTC were more likely to have larger tumor size, extrathyroidal invasion, lymph node metastasis, and more advanced stage. The 5-year DFS rate was 86.0% for SBiPTC patients and 94.0% for UiPTC patients (p = 0.013). The prevalence of BRAF (V600E) mutation in the SBiPTC group was significantly higher than that in the UiPTC group (65.7% vs. 50.4%; p = 0.038).

CONCLUSIONS

Patients with SBiPTC present with more advanced tumor stage and have shorter disease-free survival than UiPTC patients. Poorer outcomes of these patients may be at least partially explained by the high incidence of BRAF (V600E) mutation.

Molecular analysis of thyroid tumors

Thyroid cancer is the most common endocrine malignancy, and its incidence is rising in the USA and other countries. Papillary and follicular thyroid carcinomas are the two most common types of thyroid cancer. Non-overlapping genetic alterations, including BRAF and RAS point mutations, and RET/PTC and PAX8/PPARγ rearrangements, are found in more than 70% of papillary and follicular thyroid carcinomas. These represent the most common genetic alterations in thyroid cancer, as well as molecular markers of diagnostic and prognostic significance. The use of these and other emerging molecular markers will likely improve the diagnosis of malignancy in thyroid nodules as well as facilitate more individualized operative and postoperative management. Herein, we provide a brief overview of the common genetic alterations in papillary and follicular thyroid carcinoma and discuss the diagnostic and prognostic significance thereof.

Molecular genetics and diagnosis of thyroid cancer

Thyroid cancer is a common type of endocrine malignancy, and its incidence has been steadily increasing in many regions of the world. Initiation and progression of thyroid cancer involves multiple genetic and epigenetic alterations, of which mutations leading to the activation of the MAPK and PI3K-AKT signaling pathways are crucial. Common mutations found in thyroid cancer are point mutation of the BRAF and RAS genes as well as RET/PTC and PAX8/PPARγ chromosomal rearrangements. The mutational mechanisms seem to be linked to specific etiologic factors. Chromosomal rearrangements have a strong association with exposure to ionizing radiation and possibly with DNA fragility, whereas point mutations probably arise as a result of chemical mutagenesis. A potential role of dietary iodine excess in the generation of BRAF point mutations has also been proposed. Somatic mutations and other molecular alterations have been recognized as helpful diagnostic and prognostic markers for thyroid cancer and are beginning to be introduced into clinical practice, to offer a valuable tool for the management of patients with thyroid nodules.

Molecular diagnostics of thyroid tumors

CONTEXT

Thyroid cancer is the most common type of endocrine malignancy and its incidence is steadily increasing. Papillary carcinoma and follicular carcinoma are the most common types of thyroid cancer and represent those tumor types for which use of molecular markers for diagnosis and prognostication is of high clinical significance.

OBJECTIVE

To review the most common molecular alterations in thyroid cancer and their diagnostic and prognostic utility.

DATA SOURCES

PubMed (US National Library of Medicine)-available review articles, peer-reviewed original articles, and experience of the author.

CONCLUSIONS

The most common molecular alterations in thyroid cancer include BRAF and RAS point mutations and RET/PTC and PAX8/PPAR γ rearrangements. These nonoverlapping genetic alterations are found in more than 70% of papillary and follicular thyroid carcinomas. These molecular alterations can be detected in surgically resected samples and fine-needle aspiration samples from thyroid nodules and can be of significant diagnostic use. The diagnostic role of BRAF mutations has been studied most extensively, and recent studies also demonstrated a significant diagnostic utility of RAS, RET/PTC, and PAX8/PPAR γ mutations, particularly in thyroid fine-needle aspiration samples with indeterminate cytology. In addition to the diagnostic use, BRAF V600E mutation can also be used for tumor prognostication, as this mutation is associated with higher rate of tumor recurrence and tumor-related mortality. The use of these and other emerging molecular markers is expected to improve significantly the accuracy of cancer diagnosis in thyroid nodules and allow more individualized surgical and postsurgical management of patients with thyroid cancer.

Mutational and clinico-pathological analysis of papillary thyroid carcinoma in Serbia

Molecular pathogenesis of papillary thyroid carcinoma (PTC) is largely associated with mutational changes in the BRAF, RAS family and RET genes. Our aim was to assess clinico-pathological and prognostic correlations of these PTC-specific gene alterations, with a particular emphasis on the BRAF mutation, in a group of 266 Serbian PTC patients, for the first time. The reference center-based retrospective cohort included 201 (75.6%) females and 65 (24.4%) males aged 48.0±16.1 years (8-83 years old, range) diagnosed and treated for PTC during 1993-2008. Follow-up period was 53.1±41.6 months (7-187 months, range). BRAF and RAS mutations were determined by direct sequencing of genomic DNA. RET/PTC rearrangements were analyzed by RT-PCR/Southern blotting. Genetic alterations were detected in 150/266 tumors (56.4%). One tumor displayed two genetic alterations. The BRAF(V600E) was found in 84/266 (31.6%) cases, RAS mutations in 11/266 (4.1%) and RET/PTC in 55/266 (20.7%; 42/266 (15.8%) RET/PTC1 and 13/266 (4.9%) RET/PTC3). On multivariate analysis BRAF(V600E) was associated with the classical papillary morphology (P = 0.05), the higher pT category (P = 0.05) and advanced clinical stage (P = 0.03). In a proportional hazard model, BRAF(V600E) did not appear to be an independent risk factor for the faster recurrence (P = 0.784). We conclude that under the extensive thyroid surgery and limited application of radioiodine ablation BRAF(V600E) may not be an indicator of poorer disease-free survival during the short to middle follow-up period. However, it has a potential to contribute to patients stratification into high- and low-risk groups.

Galectin-3 promotes chronic activation of K-Ras and differentiation block in malignant thyroid carcinomas

Anaplastic thyroid carcinomas are deadly tumors that are highly invasive, particularly into the bones. Although oncogenic Ras can transform thyroid cells into a severely malignant phenotype, thyroid carcinomas do not usually harbor ras gene mutations. Therefore, it is not known whether chronically active Ras contributes to thyroid carcinoma cell proliferation, although galectin-3 (Gal-3), which is strongly expressed in thyroid carcinomas but not in benign tumors or normal glands, is known to act as a K-Ras chaperone that stabilizes and drives K-Ras.GTP nanoclustering and signal robustness. Here, we examined the possibility that thyroid carcinomas expressing high levels of Gal-3 exhibit chronically active K-Ras. Using cell lines representing three types of malignant thyroid tumors--papillary, follicular, and anaplastic--we investigated the possible correlation between Gal-3 expression and active Ras content, and then examined the therapeutic potential of the Ras inhibitor S-trans, trans-farnesylthiosalicylic acid (FTS; Salirasib) for thyroid carcinoma. Thyroid carcinoma cells strongly expressing Gal-3 showed high levels of K-Ras.GTP expression, and K-Ras.GTP transmitted strong signals to extracellular signal-regulated kinase. FTS disrupted interactions between Gal-3 and K.Ras, strongly reduced K-Ras.GTP and phospho-extracellular signal-regulated kinase expression, and enhanced the expression of the cell cycle inhibitor p21 as well as of the thyroid transcription factor 1, which is involved in thyroid cell differentiation. FTS also inhibited anaplastic thyroid carcinoma cell proliferation in vitro and tumor growth in nude mice. We conclude that wild-type K-Ras.GTP in association with Gal-3 contributes to thyroid carcinoma malignancy and that Ras inhibition might be a useful treatment strategy against these deadly tumors.

Signal transduction in the human thyrocyte and its perversion in thyroid tumors

The study of normal signal transduction pathways regulating the proliferation and differentiation of a cell type allows to predict and to understand the perversions of these pathways which lead to tumorigenesis. In the case of the human thyroid cell, three cascades are mostly involved in tumorigenesis: The pathways and genetic events affecting them are described. Caveats in the use of models and the interpretation of results are formulated and the still pending questions are outlined.

High Prevalence of B-RAF Mutation in Papillary Carcinoma of the Thyroid in North-East Italy

B-RAF V600E mutation is frequently observed in several tumors, including papillary thyroid carcinomas (PTCs), where it is considered of potential diagnostic and prognostic value. The reported prevalence of B-RAF mutation in PTCs in different Italian populations varies from 14% to 69%. The authors investigate the prevalence and utility of the B-RAF V600E mutation in a series of 91 fine needle aspiration biopsies (FNABs) of the thyroid and in 60 histologically proven PTCs in a well-defined north Italian population. In their series, the B-RAF mutation was detected in 43 (72%) PTCs and was more frequent in classic (34 out of 44, 77%) versus variant follicular PTCs (PTCVF; 9 out of 16, 56%). In all, 41 (46%) FNABs showed B-RAF mutation and corresponded to histologically proven PTCs (33 classic type and 8 PTCVF), which had been cytologically classified as malignant (28 cases), atypical/suspicious (10), inadequate (1), and benign (2). B-RAF mutations were never seen in non-PTC/ PTCVF FNAB cases, implying a 100% positive predictive value.These data demonstrate a high prevalence of B-RAF mutations in the present study population, underscoring the possibility of strong regional differences in B-RAF mutation prevalence in PTCs and further confirming its high diagnostic value on FNAB.

Thyroid cancer: current molecular perspectives

The thyroid cancer is a rare oncological entity, representing no more than 1% of all human malignant neoplasms. Recently, it has been demonstrated a sharp increase in incidence of differentiated thyroid carcinoma, equally occurring in both sexes. So far, multiple genetic alterations have been identified in differentiated thyroid carcinoma, leading to investigate the clinical utility of genetic studies. In particular, molecular genetic approaches searching for gene mutations in the material collected by fine needle ago-biopsy may have a particular utility in small nodules and in those specimens with an indeterminate cytology. The expansion of knowledge about genetic mutations occurring in different thyroid tumors has characterized recent years, allowing the identification of a correlation between specific mutations and phenotypic characteristics of thyroid cancers, essential for their prognosis. This review will briefly report on the histological features and the new entity represented by thyroid microcarcinoma and will focus on both environmental and genetic aspects associated with the occurrence of thyroid cancer.

Neurofibroma adjacent to the thyroid gland and a thyroid papillary carcinoma in a patient with neurofibromatosis type 1: report of a case

Neurofibromatosis (NF) type 1, also known as von Recklinghausen's disease, is an autosomal-dominant inherited disorder. Some tumors may develop in these patients, including optic pathway gliomas, astrocytomas, brainstem gliomas, chronic myeloid leukemia, and rhabdomyosarcoma. Patients with neurofibromatosis type 1 show also an increased risk of endocrine tumors, especially pheochromocytomas, whereas thyroid carcinoma is very rare. It is also rare for a neurofibroma to arise in the tissue neighboring the thyroid gland, and mimicking a nonfunctional thyroid nodule. This report presents a case of a neurofibroma adherent to the thyroid gland with thyroid papillary carcinoma in a 26-year-old woman with NF type 1.

Multiple genetic alterations in papillary thyroid cancer are associated with younger age at presentation

BACKGROUND

There is a significant gender and age disparity in thyroid cancer incidence and outcome. The molecular basis for these divergent clinical presentations and outcome are essentially unknown.

METHODS

The primary tumor genotype in 217 patients with papillary thyroid cancer was determined for six common somatic genetic alterations (RET/PTC1, RET/PTC3, and NTRK1 rearrangements, and BRAF V600E, KRAS, and NRAS hotspot mutations) by PCR and direct sequencing, and nested PCR. Univariate and multivariate analyses were performed to determine the association of genetic changes and age, gender, and other clinicopathologic factors.

RESULTS

One hundred twenty-one of the 190 conventional papillary thyroid carcinoma samples (63.7%) had at least one genetic alteration, and 27 of the samples (14.2%) had more than one alteration. In the follicular variant of papillary thyroid carcinomas, 13 of the 27 samples (48.1%) had at least one genetic alteration and three of the 27 samples (11.1%) had more than one. The presence of multiple genetic alterations was associated with younger age at diagnosis (P=0.034), mean difference of 8 y earlier. We found no significant association with the number or type of genetic alterations present by gender, tumor size, extent of tumor differentiation, multicentricity, lymph node metastasis, distant metastases, TNM stage, and the AMES risk group. The association of multiple genetic alterations and younger age were independent of tumor size, lymph node or distant metastasis, TNM stage, or AMES risk group.

CONCLUSIONS

Multiple genetic alterations are more common in younger patients with papillary thyroid cancer, but there is no difference in the type or number of genetic alterations by gender. Our findings suggest that multiple genetic alterations in thyroid cancer may be associated with earlier disease initiation and or progression.

A novel complex BRAF mutation detected in a solid variant of papillary thyroid carcinoma

BRAF gene mutations are identified in about 45% of papillary thyroid carcinomas (PTC) and represent the most common genetic event in this tumor. Here, we report a case of PTC, solid variant, with a complex BRAF mutation that involves one nucleotide substitution, C1796T, and a CTT triplet insertion, 1798_1799insCTT, located on the same allele. This mutation leads to the replacement of a threonine with an isoleucine, T599I, and replacement of a valine with an alanine and a leucine, V600delinsAL. This mutation was identified both in the preoperative fine needle aspirate sample and in the surgical specimen after total thyroidectomy. Other rare BRAF mutations in PTC are reviewed.

Follicular histotypes of oncocytic thyroid carcinomas do not carry mutations of the BRAF hot-spot

BACKGROUND

The BRAF V600E mutation is the most prevalent genetic aberration in papillary thyroid carcinomas (PTCs), and it is found exclusively in RET/PTC-negative tumors. In oncocytic (Hürthle cell, oxyphilic) thyroid tumors, the presence of RET/PTC rearrangements is associated with either the conventional papillary histotype or the "solid" Hürthle cell tumors, whereas all predominantly follicular oncocytic carcinomas do not harbor RET/PTC chimeras. Although 12% of tumors of the follicular variant of PTC carry BRAF mutations, none of the few oncocytic follicular thyroid adenomas (oncoAd) or carcinomas (oncoFTC) published worldwide tested positive. An aspired molecular-based classification of oncocytic thyroid tumors is in need of additional evidence on BRAF mutations in the follicular histotype.

METHODS

A series of 44 oncocytic thyroid tumors with well-documented clinicopathological data was subjected to BRAF mutation analysis (complete exon 15) by automated sequencing.

RESULTS

The series of oncocytic thyroid tumors consisted of 21 adenomas (oncoAds: 17 females, 4 males; mean age, 54.5 years; range, 27-80 years), 20 follicular carcinomas (oncoFTCs: 14 females, 6 males; mean age, 61.4 years; range, 39-80 years), and 3 "classic" papillary carcinomas (oncoPTCs: 3 females; mean age, 58.1 years; range, 46-70 years; 3x T2 tumors). The follicular variants of oncocytic cancers are divided into 11x T2, 5x T3, and 4x T4 tumor stages (International Union Against Cancer [UICC] TNM 5th edition). None of the 44 neoplasms of the presented series demonstrated genetic alterations in the BRAF hot-spot region (exon 15, codons 599-601). Congruently, 0/10 oncoAd and 0/20 oncoFTC described in the literature so far carried BRAF V600E mutations.

CONCLUSIONS

Our results add to the evidence that, in contrast to follicular variants of oncoPTCs, predominantly follicular oncocytic thyroid tumors harbor neither RET/PTC rearrangements nor BRAF mutations. Furthermore, the findings support the concept that oncocytic neoplasms of the thyroid gland are oncocytic counterparts of the respective histotype (adenoma, FTC, PTC, or poorly differentiated thyroid carcinoma) rather than a separate tumor entity. Molecular characterization of oncocytic thyroid malignancies for RET/PTC or BRAF genetic alterations may help with (preoperative) classification and prognostic evaluation of these tumors.

Intragenic mutations in thyroid cancer

The close genotype-phenotype relationship that characterizes thyroid oncology stimulated the authors to address this article by using a mixed, genetic and phenotypic approach. As such, this article addresses the following aspects of intragenic mutations in thyroid cancer: thyroid stimulating hormone receptor and guanine-nucleotide-binding proteins of the stimulatory family mutations in hyperfunctioning tumors; mutations in RAS and other genes and aneuploidy; PAX8-PPARgamma rearrangements; BRAF mutations; mutations in oxidative phosphorylation and Krebs cycle genes in Hürthle cell tumors; mutations in succinate dehydrogenase genes in medullary carcinoma and C-cell hyperplasia; and mutations in TP53 and other genes in poorly differentiated and anaplastic carcinomas.

Thyroid carcinoma: molecular pathways and therapeutic targets

Thyroid cancer is the most common malignant tumor of the endocrine system. The most frequent type of thyroid malignancy is papillary carcinoma. These tumors frequently have genetic alterations leading to the activation of the mitogen-activated protein kinase (MAPK) signaling pathway. Most common mutations in papillary carcinomas are point mutations of the BRAF and RAS genes and RET/PTC rearrangement. These genetic alterations are found in >70% of papillary carcinomas and they rarely overlap in the same tumor. Most frequent alterations in follicular carcinomas, the second most common type of thyroid malignancy, include RAS mutations and PAX8-PPARgamma rearrangement. RET point mutations are crucial for the development of medullary thyroid carcinomas. Many of these mutations, particularly those leading to the activation of the MAPK pathway, are being actively explored as therapeutic targets for thyroid cancer. A number of compounds have been studied and showed antitumor effects in preclinical studies and are being tested in ongoing clinical trials.

BRAF mutation associated with other genetic events identifies a subset of aggressive papillary thyroid carcinoma

PURPOSE

BRAF(V600E) mutation represents the most common oncogenic event in sporadic papillary thyroid cancer (PTC). There are, however, significant discrepancies regarding the overall frequency, its prevalence in PTC-variants, and its relationship with clinico-pathological parameters of poor outcome. Moreover, the impact of BRAF(V600E) mutants on tumour-related patient's death has not been evaluated.

DESIGN

We analysed, by PCR-SSCP and/or PCR-direct sequencing, exons 8, 10, 11 and 15 of BRAF in 113 tumour samples from 49 PTC-patients. Matched lymph node metastases and/or distant metastases (DMs) were screened in 35 patients. Focal changes in the growth pattern or microscopic grade within the primary tumour (Pt) or the metastases were separately genotyped. Mutations at H-, K-, N-ras and PIK3CA exons 9 and 20 were also investigated. For comparison with PTC cases, the BRAF and Ras mutational status was evaluated in 89 specimens obtained from 24 poorly differentiated thyroid carcinomas (PDCs) and 36 anaplastic thyroid carcinomas (ATCs).

RESULTS

BRAF(V600E) was found in 13/16 classical PTCs (CL-PTCs), 6/17 follicular variant PTCs (FV-PTCs) and 8/16 mixed (papillary/follicular) PTCs (Mx-PTCs), being significantly associated with CL-PTCs (P = 0.015). BRAF(V600E) segregated with metastatic PTC-cells in 43% of the patients, but only one DM disclosed the mutation. PTC-tumours featuring concurrent less-differentiated foci were BRAF wild-type in both components. Noteworthy, the frequency of BRAF mutations among PDCs and ATCs resulted considerably lower (16.6% and 25%, respectively) than in PTCs (55%). The prevalence of Ras mutations among PDCs and ATCs (46% and 36%, respectively) was, however, much higher than in PTCs (14%). Five (71%) of the patients who died of PTC displayed somatic mutations. Four of them had other gene alteration associated with BRAF(V600E) and the only one that did not, BRAF(V600E) was restricted to the Pt. The occurrence of BRAF(V600E) associated with other genetic events was an independent predictor of DMs during follow-up, recurrence and tumour-related death. Remarkably, two PDCs (8.3%) and five ATCs (14%) revealed concurrent BRAF and Ras mutations.

CONCLUSION

BRAF(V600E)'alone' does not represent a marker for poor outcome, however, when associated with alterations in other genes identifies a subset of PTCs with increased risk of recurrence and decreased survival.

Incidentally simultaneous occurrence of RET/PTC, H4-PTEN and BRAF mutation in papillary thyroid carcinoma

Because interaction existed between PTEN and RET-RAS-RAF-MAPK pathway, H4-PTEN (a newly identified gene rearrangement), RET/PTC and BRAF mutation were scanned in 125 Chinese patients with papillary thyroid carcinoma (PTC). H4-PTEN were detected in 9.6% of PTC and the frequency of the occurrence of BRAF mutation and/or RET/PTC in H4-PTEN positive tumors was extremely high (75%). On the other hand, age has an important effect on the aberration formation and young age renders more prone to multi-genetic events. A combinational scanning of these involved changes will improve the predictive value of molecular aberrations in the treatment of PTC.

Molecular genetics of thyroid cancer: implications for diagnosis, treatment and prognosis

Thyroid cancer is the most common malignant tumor of the endocrine system and accounts for approximately 1% of all newly diagnosed cancer cases. The most frequent type of thyroid malignancy is papillary carcinoma, which constitutes approximately 80% of all cases. Papillary carcinomas frequently have genetic alterations leading to the activation of the MAPK signal pathway. Those include RET/PTC rearrangement and point mutations of the BRAF and RAS genes. Mutations in these genes are found in over 70% of papillary carcinomas and they rarely overlap in the same tumor. Frequent genetic alterations in follicular carcinomas, the second most common type of thyroid malignancy, include RAS mutations and PAX8-PPAR gamma rearrangement. RET point mutations are crucial for the development of medullary thyroid carcinomas. Many of these mutations, particularly those leading to the activation of the MAPK pathway, are being actively explored as therapeutic targets for thyroid cancer. Detection of these genetic alterations using molecular techniques is important for preoperative fine-needle aspiration diagnosis, prognosis and treatment of thyroid cancer.