Whole-genome sequencing of synchronous thyroid carcinomas identifies aberrant DNA repair in thyroid cancer dedifferentiation

Could SLC26A7 Be a Promising Marker for Preoperative Diagnosis of High-Grade Papillary Thyroid Carcinoma?

BACKGROUND/OBJECTIVES

A modern classification distinguishes between two nosological entities posing an intermediate risk between differentiated and anaplastic carcinoma: poorly differentiated thyroid carcinoma and differentiated high-grade thyroid carcinoma. There are currently few studies searching for the preoperative molecular genetic markers of high-grade papillary thyroid carcinoma (PTC HG), primarily because of a recent WHO reclassification and singling out of a separate entity: high-grade follicular cell-derived nonanaplastic thyroid carcinoma. Therefore, this work was aimed at identifying PTC HG-specific microRNAs and mRNAs that reliably distinguish them from differentiated papillary thyroid carcinoma in preoperative cytology specimens (fine-needle aspiration biopsies).

METHODS

A molecular genetic profile (expression levels of 14 genes and eight microRNAs) was studied in 110 cytology specimens from patients with PTC: 13 PTCs HG and 97 PTCs without features of HG.

RESULTS

Of the examined eight microRNAs and 14 genes, significant differences in the expression levels between the PTC and PTC HG groups were revealed for genes SLC26A7, TFF3, and TPO. Only one gene (SLC26A7) proved to be crucial for detecting PTC HG. It showed the largest area under the ROC curve (0.816) in differentiation between the PTC and PTC HG groups and was the key element of the decision tree by ensuring 54% sensitivity and 87.6% specificity.

CONCLUSIONS

Early preoperative diagnosis of PTC HG in patients with early stages of this cancer type will allow clinicians to modify a treatment strategy toward a larger surgery volume and lymph node dissection and may provide indications for subsequent radioactive iodine therapy.

Aggressive Types of Malignant Thyroid Neoplasms

Differentiated thyroid cancer (DTC) includes many subtypes, which demonstrate favorable to aggressive behavior. During the past decades, efforts have been made to describe aggressive thyroid cancers. Within DTC, aggressive variants constitute rare entities with unique histopathological features and compromised survival, as local and distant metastatic disease is frequent. In recent years, the distinct category of poorly differentiated thyroid cancer was introduced in 2004 and the type of differentiated high-grade thyroid carcinoma was recently added in the 2022 WHO classification of thyroid neoplasms. Finally, anaplastic thyroid cancer exhibits a rapid, resistant to therapy, progression and confers the shortest survival. In this review, we will present the characteristics of these thyroid cancer types and also discuss the treatment, management, and follow-up of these difficult cases. Emphasis was given to recent bibliography of the last decade.

Management of Poorly Differentiated Thyroid Cancer and Differentiated High-Grade Thyroid Carcinoma

Thyroid carcinoma of follicular cell origin exists on a histopathologic and clinical spectrum. The authors focus on the category of tumors that fall between the very favorable well-differentiated thyroid carcinomas and the very unfavorable anaplastic thyroid carcinomas. These intermediately aggressive tumors include poorly differentiated thyroid carcinoma and the newly defined differentiated high-grade thyroid carcinoma. Both diagnoses require certain histopathologic requirements be met in order to accurately identify these tumors post-operatively. Management remains primarily surgical though adjunctive treatments such as molecular targeted therapies (eg, tyrosine kinase inhibitors) and differentiation therapy (to restore tumor response to radioactive iodine) are also becoming available.

Spatial Transcriptomics in a Case of Follicular Thyroid Carcinoma Reveals Clone-Specific Dysregulation of Genes Regulating Extracellular Matrix in the Invading Front

Follicular thyroid carcinoma (FTC) is recognized by its ability to invade the tumor capsule and blood vessels, although the exact molecular signals orchestrating this phenotype remain elusive. In this study, the spatial transcriptional landscape of an FTC is detailed with comparisons between the invasive front and histologically indolent central core tumor areas. The Visium spatial gene expression platform allowed us to interrogate and visualize the whole transcriptome in 2D across formalin-fixated paraffin-embedded (FFPE) tissue sections. Four different 6 × 6 mm areas of an FTC were scrutinized, including regions with capsular and vascular invasion, capsule-near area without invasion, and a central core area of the tumor. Following successful capturing and sequencing, several expressional clusters were identified with regional variation. Most notably, invasive tumor cell clusters were significantly over-expressing genes associated with pathways interacting with the extracellular matrix (ECM) remodeling and epithelial-to-mesenchymal transition (EMT). Subsets of these genes (POSTN and DPYSL3) were additionally validated using immunohistochemistry in an independent cohort of follicular thyroid tumors showing a clear gradient pattern from the core to the periphery of the tumor. Moreover, the reconstruction of the evolutionary tree identified the invasive clones as late events in follicular thyroid tumorigenesis. To our knowledge, this is one of the first 2D global transcriptional mappings of FTC using this platform to date. Invasive FTC clones develop in a stepwise fashion and display significant dysregulation of genes associated with the ECM and EMT - thus highlighting important molecular crosstalk for further investigations.

Polymorphisms of DNA Repair Genes in Thyroid Cancer

The incidence of thyroid cancer, one of the most common forms of endocrine cancer, is increasing rapidly worldwide in developed and developing countries. Various risk factors can increase susceptibility to thyroid cancer, but particular emphasis is put on the role of DNA repair genes, which have a significant impact on genome stability. Polymorphisms of these genes can increase the risk of developing thyroid cancer by affecting their function. In this article, we present a concise review on the most common polymorphisms of selected DNA repair genes that may influence the risk of thyroid cancer. We point out significant differences in the frequency of these polymorphisms between various populations and their potential relationship with susceptibility to the disease. A more complete understanding of these differences may lead to the development of effective prevention strategies and targeted therapies for thyroid cancer. Simultaneously, there is a need for further research on the role of polymorphisms of previously uninvestigated DNA repair genes in the context of thyroid cancer, which may contribute to filling the knowledge gaps on this subject.

Characterization of the genomic alterations in poorly differentiated thyroid cancer

Poorly differentiated thyroid carcinoma (PDTC) is a subtype of thyroid cancer that has a high rate of metastasis or recurrence and a relatively poor prognosis. However, there are few studies that have been conducted on PDTC at the whole protein-coding gene scale. Here, we performed genomic profiling of 15 patients with PDTC originated from follicular thyroid carcinoma using whole exome sequencing and also performed gene functional enrichment analysis of differentially expressed genes (DEGs) for three patients. Further, we investigated genetic variants associated with PDTC progression and the characteristics of clinical pathology. We revealed somatic genomic alterations in the RAF1, MAP2K2, and AKT2 genes that were not reported in previous studies. We confirmed frequent occurrences in the RAS gene in patients with PDTC; the genetic alterations were associated with the RAS-RAF-MEK-ERK/JNK, PI3K-AKT-mTOR signaling pathways, and the cell cycle. DEG analysis showed that immune response was lower in cancer tissues than in normal tissues. Through the association analysis of somatic mutations and the characteristics of clinical pathology from patients with PDTC, the somatic mutations of ABCA12, CLIP1, and ATP13A3 were significantly associated with a vascular invasion phenotype. By providing molecular genetic insight on PDTC, this study may contribute to the discovery of novel therapeutic target candidates.

Advances and challenges in thyroid cancer: The interplay of genetic modulators, targeted therapies, and AI-driven approaches

Thyroid cancer continues to exhibit a rising incidence globally, predominantly affecting women. Despite stable mortality rates, the unique characteristics of thyroid carcinoma warrant a distinct approach. Differentiated thyroid cancer, comprising most cases, is effectively managed through standard treatments such as thyroidectomy and radioiodine therapy. However, rarer variants, including anaplastic thyroid carcinoma, necessitate specialized interventions, often employing targeted therapies. Although these drugs focus on symptom management, they are not curative. This review delves into the fundamental modulators of thyroid cancers, encompassing genetic, epigenetic, and non-coding RNA factors while exploring their intricate interplay and influence. Epigenetic modifications directly affect the expression of causal genes, while long non-coding RNAs impact the function and expression of micro-RNAs, culminating in tumorigenesis. Additionally, this article provides a concise overview of the advantages and disadvantages associated with pharmacological and non-pharmacological therapeutic interventions in thyroid cancer. Furthermore, with technological advancements, integrating modern software and computing into healthcare and medical practices has become increasingly prevalent. Artificial intelligence and machine learning techniques hold the potential to predict treatment outcomes, analyze data, and develop personalized therapeutic approaches catering to patient specificity. In thyroid cancer, cutting-edge machine learning and deep learning technologies analyze factors such as ultrasonography results for tumor textures and biopsy samples from fine needle aspirations, paving the way for a more accurate and effective therapeutic landscape in the near future.

Mutational profiling of Chinese patients with thyroid cancer

Background

The incidence of thyroid cancer in China has rapidly increased in recent decades. As the genetic profiles of thyroid cancer vary dramatically between different geographical regions, a comprehensive genetic landscape of thyroid cancer in the Chinese population is urgently needed.

Methods

We retrospectively included thyroid cancer patients from three Chinese medical centers between February 2015 and August 2020. To dissect the genomic profiling of these patients, we performed targeted next-generation sequencing on their tumor tissues using a 1,021-gene panel.

Results

A total of 458 Chinese patients with thyroid cancer were enrolled, including four malignant histological subtypes arising from follicular epithelial thyroid cells. BRAF driver mutations were identified in 76.0% of patients, followed by RET rearrangements (7.6%) and RAS driver mutations (4.1%). Tumors with more somatic mutations correlated with worse clinical characteristics, including older age at diagnosis, less differentiation of tumor, larger tumor size, lymph node metastasis and distal metastasis. Subclonal BRAF mutations occurred in 20% (6/30) of patients and were frequent in poorly differentiated or anaplastic tumors (33.3% [2/6] vs. 4.2% [1/24], P = 0.09) and those with distal metastasis (50.0% [2/4] vs. 8.7% [2/23], P = 0.09). Tumors with TERT promoter mutations had significantly more somatic mutations (average: 6.5 vs. 1.8, P < 0.001). Moreover, TERT promoter mutations were not associated with lymph node metastasis but significantly associated with older age at diagnosis and poorly differentiated or anaplastic tumors, regardless of their clonal architecture.

Conclusion

Our results shed light on the molecular pathogenesis and clinical characteristics of thyroid cancer in the Chinese population. The number of somatic mutations, TERT promoter mutations, and the clonal architecture of BRAF mutations should be considered in the risk stratification of thyroid cancer.

KRAS Hijacks the miRNA Regulatory Pathway in Cancer

Extensive studies have focused on the misregulation of individual miRNAs in cancer. More recently, mutations in the miRNA biogenesis and processing machinery have been implicated in several malignancies. Such mutations can lead to global miRNA misregulation, which may promote many of the well-known hallmarks of cancer. Interestingly, recent evidence also suggests that oncogenic Kristen rat sarcoma viral oncogene homolog (KRAS) mutations act in part by modulating the activity of members of the miRNA regulatory pathway. Here, we highlight the vital role mutations in the miRNA core machinery play in promoting malignant transformation. Furthermore, we discuss how mutant KRAS can simultaneously impact multiple steps of miRNA processing and function to promote tumorigenesis. Although the ability of KRAS to hijack the miRNA regulatory pathway adds a layer of complexity to its oncogenic nature, it also provides a potential therapeutic avenue that has yet to be exploited in the clinic. Moreover, concurrent targeting of mutant KRAS and members of the miRNA core machinery represents a potential strategy for treating cancer.

Surgery After BRAF-Directed Therapy Is Associated with Improved Survival in BRAFV600E Mutant Anaplastic Thyroid Cancer: A Single-Center Retrospective Cohort Study

Background: The aim of this study was to describe the oncologic outcomes of patients with BRAF^V600E-mutated anaplastic thyroid cancer (ATC) who had neoadjuvant BRAF-directed therapy with subsequent surgery. For context, we also reviewed patients who received BRAF-directed therapy after surgery, and those who did not have surgery after BRAF-directed therapy. Methods: This was a single-center retrospective cohort study conducted at a tertiary care cancer center in Texas from 2017 to 2021. Fifty-seven consecutive patients with BRAF^V600E-mutated ATC and at least 1 month of BRAF-directed therapy were included. Primary outcomes were overall survival (OS) and progression-free survival (PFS). Results: All patients had stage IVB (35%) or IVC (65%) ATC. Approximately 70% of patients treated with BRAF-directed therapy ultimately had surgical resection of residual disease. Patients who had neoadjuvant BRAF-directed therapy followed by surgery (n = 32) had 12-month OS of 93.6% [confidence interval (CI) 84.9-100] and PFS of 84.4% [CI 71.8-96.7]. Patients who had surgery before BRAF-directed therapy (n = 12) had 12-month OS of 74.1% [CI 48.7-99.5] and PFS of 50% [CI 21.7-78.3]. Finally, patients who did not receive surgery after BRAF-directed therapy (n = 13) had 12-month OS of 38.5% [CI 12.1-64.9] and PFS of 15.4% [CI 0-35.0]. Neoadjuvant BRAF-directed therapy reduced tumor size, extent of surgery, and surgical morbidity score. Subgroup analysis suggested that any residual ATC in the surgical specimen was associated with significantly worse 12-month OS and PFS (OS = 83.3% [CI 62.6-100], PFS = 61.5% [CI 35.1-88]) compared with patients with pathologic ATC complete response (OS = 100%, PFS = 100%). Conclusions: We observed that neoadjuvant BRAF-directed therapy reduced extent of surgery and surgical morbidity. While acknowledging potential selection bias, the 12-month OS rate appeared higher in patients who had BRAF-directed therapy followed by surgery as compared with BRAF-directed therapy without surgery; yet, it was not significantly different from surgery followed by BRAF-directed therapy. PFS appeared higher in patients treated with neoadjuvant BRAF-directed therapy relative to patients in the other groups. These promising results of neoadjuvant BRAF-directed therapy followed by surgery for BRAF-mutated ATC should be confirmed in prospective clinical trials.

On the Chopping Block: Overview of DICER1 Mutations in Endocrine and Neuroendocrine Neoplasms

Mutational inactivation of the DICER1 gene causes aberrant micro-RNA maturation, which in turn may have consequences for the posttranscriptional regulation of gene expression, thereby contributing to tumor formation in various organs. Germline DICER1 mutations cause DICER1 syndrome, a pleiotropic condition with an increased risk of various neoplastic conditions in the pleura, ovaries, thyroid, pituitary, pineal gland, and mesenchymal tissues. Somatic DICER1 mutations are also frequently observed in a wide variety of solid tumors, thereby highlighting the importance of this gene in tumor development. In this review, the importance of DICER1 inactivation in endocrine tumors is discussed.

The 2022 WHO classification of thyroid tumors: novel concepts in nomenclature and grading

The fifth edition of the Classification of Endocrine and Neuroendocrine Tumors has been released by the World Health Organization. This timely publication integrates several changes to the nomenclature of non-neoplastic and neoplastic thyroid diseases, as well as novel concepts that are essential for patient management. The heterogeneous group of non-neoplastic and benign neoplastic lesions are now collectively termed as 'thyroid follicular nodular disease' to better reflect the clonal and non-clonal proliferations that clinically present as multinodular goiter. Thyroid neoplasms originating from follicular cells are distinctly divided into benign, low-risk and malignant neoplasms. The new classification scheme stresses that papillary thyroid carcinoma (PTC) should be subtyped based on histomorphologic features irrespective of tumor size to avoid treating all sub-centimeter/small lesions as low-risk disease. Formerly known as the cribriform-morular variant of PTC is redefined as cribriform-morular thyroid carcinoma since this tumor is now considered a distinct malignant thyroid neoplasm of uncertain histogenesis. The 'differentiated high-grade thyroid carcinoma' is a new diagnostic category including PTCs, follicular thyroid carcinomas and oncocytic carcinomas with high-grade features associated with poorer prognosis similar to the traditionally defined poorly differentiated thyroid carcinoma as per Turin criteria. In addition, squamous cell carcinoma of the thyroid is now considered a morphologic pattern/subtype of anaplastic thyroid carcinoma. In this review, we will highlight the key changes in the newly devised fifth edition of the WHO classification scheme of thyroid tumors with reflections on its applicability in patient management and future directions in this field.

Molecular features of aggressive thyroid cancer

Poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) have a worse prognosis with respect to well differentiated TC, and the loss of the capability of up-taking ¹³¹I is one of the main features characterizing aggressive TC. The knowledge of the genomic landscape of TC can help clinicians to discover the responsible alterations underlying more advance diseases and to address more tailored therapy. In fact, to date, the antiangiogenic multi-targeted kinase inhibitor (aaMKIs) sorafenib, lenvatinib, and cabozantinib, have been approved for the therapy of aggressive radioiodine (RAI)-resistant papillary TC (PTC) or follicular TC (FTC). Several other compounds, including immunotherapies, have been introduced and, in part, approved for the treatment of TC harboring specific mutations. For example, selpercatinib and pralsetinib inhibit mutant RET in medullary thyroid cancer but they can also block the RET fusion proteins-mediated signaling found in PTC. Entrectinib and larotrectinib, can be used in patients with progressive RAI-resistant TC harboring TRK fusion proteins. In addition FDA authorized the association of dabrafenib (BRAF^V600E inhibitor) and trametinib (MEK inhibitor) for the treatment of BRAF^V600E-mutated ATC. These drugs not only can limit the cancer spread, but in some circumstance they are able to induce the re-differentiation of aggressive tumors, which can be again submitted to new attempts of RAI therapy. In this review we explore the current knowledge on the genetic landscape of TC and its implication on the development of new precise therapeutic strategies.

Cathepsin F genetic mutation is associated with familial papillary thyroid cancer

BACKGROUND

Thyroid cancer is one of the most common cancers in the world. Genetic factors are important in the occurrence and development of thyroid cancer, and genetic diagnosis has become an important basis for the prognosis of benign and malignant nodules. We identify a family of six siblings with inherited thyroid cancer susceptibility. All six members of this generation have been definitely diagnosed with papillary thyroid carcinoma. This work aims at confirming the relevant causative genes for thyroid cancer in this pedigree.

METHODS

We extract DNA from the peripheral blood of six individuals and perform whole genome sequencing. Sanger sequencing and immunohistochemistry further testify the cathepsin F (CTSF) mutation and expression.

RESULTS

We identify 57 single nucleotide variations (SNVs) out of at least 4 affected family members via certain filter criteria. The CTSF gene found in five of the six family members is here considered the most promising candidate gene mutation for familial thyroid cancer. Besides, our research also proves several known genes including CTSB, TEKT4, ESR1, MSH6, DIRC3, GNAS, and BANCR that act as probable oncogenic drivers in this family. The Sanger sequencing identifies the existence and veracity of CTSF somatic mutations. The CTSF immunohistochemistry of thyroid cancer tissue specimens displays that higher CTSF expression in mutated patients than that in wild-type patient as well as pericarcinomatous tissue.

CONCLUSIONS

We conclude that the evaluation of CTSF gene mutations of patients in thyroid cancer families may be predictive and valuable for the familial heredity of thyroid cancer.

Thyroid cancer harboring PTEN and TP53 mutations: A peculiar molecular and clinical case report

To date, the molecular mechanisms that underline aggressiveness and resistance to tyrosine kinase inhibitors in some thyroid carcinomas (TCs) are not known yet. We report the case of a young patient with a metastatic poorly differentiated (PDTC) and follicular thyroid carcinoma (FTC) refractory to conventional therapies and to Sorafenib. The patient, despite an initial partial response, died of progressive disease 21 months after diagnosis. The genetic analysis performed on the primary tumor and on lymph nodes and distant metastases allowed to identify a frameshift mutation (p.P248Tfs*5) in the PTEN gene, never described in TC. This mutation was present in the primary tumor and, with a lower allelic frequency, in metastases diagnosed after treatment with Sorafenib. Mutations in TP53 (p.C135Y and c.920-2A>G previously detected in anaplastic carcinomas and p.M133R never found in TC) were also detected in the primary tissue together with a mono-allelic expression of the p.C135Y mutant at RNA level. At metastatic sites level, we found only the TP53 splicing mutation c.920-2A>G. The presence of defects in mismatch repair (MMR) proteins and genomic instability was also evaluated. The primary tumor showed a partial expression of MMR proteins together with a strong genomic instability. In conclusion, we demonstrated that the rare combination of somatic PTEN and TP53 mutations in a patient with a metastatic FTC, together with the presence of tumor heterogeneity and genomic instability, might be associated with a high tumor aggressiveness and resistance to treatments.

A case of osteoclastic variant of anaplastic thyroid carcinoma: Diagnostic and prognostic marker studies by cytology

Anaplastic thyroid carcinoma is an infrequent, but aggressive fatal subtype of thyroid cancer. The osteoclastic variant of anaplastic carcinoma is a rare subtype of anaplastic carcinoma with rare cases reported in the literature. Molecular targeted therapies have emerged for the anaplastic carcinoma, necessitating accurate pathologic diagnosis with additional ancillary testing for directing clinical management. We present here the cytological diagnosis of an anaplastic thyroid carcinoma-osteoclastic variant on fine-needle aspiration (FNA), with emphasis on the novelty of utilizing the least invasive procedure (aspiration cytology) for rendering pathological diagnosis as well as identifying potential prognostic markers for targeted immunotherapy.

Poorly differentiated thyroid carcinoma: a clinician's perspective

Poorly differentiated thyroid carcinoma (PDTC) is a rare thyroid carcinoma originating from follicular epithelial cells. No explicit consensus can be achieved to date due to sparse clinical data, potentially compromising the outcomes of patients. In this comprehensive review from a clinician's perspective, the epidemiology and prognosis are described, diagnosis based on manifestations, pathology, and medical imaging are discussed, and both traditional and emerging therapeutics are addressed as well. Turin consensus remains the mainstay diagnostic criteria for PDTC, and individualized assessments are decisive for treatment option. The prognosis is optimal if complete resection is performed at early stage but dismal in nearly half of patients with locally advanced and/or distant metastatic diseases, in which adjuvant therapies such as 131I therapy, external beam radiation therapy, and chemotherapy should be incorporated. Emerging therapeutics including molecular targeted therapy, differentiation therapy, and immunotherapy deserve further investigations to improve the prognosis of PDTC patients with advanced disease.

Overview of the 2022 WHO Classification of Thyroid Neoplasms

This review summarizes the changes in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the thyroid gland. The new classification has divided thyroid tumors into several new categories that allow for a clearer understanding of the cell of origin, pathologic features (cytopathology and histopathology), molecular classification, and biological behavior. Follicular cell-derived tumors constitute the majority of thyroid neoplasms. In this new classification, they are divided into benign, low-risk, and malignant neoplasms. Benign tumors include not only follicular adenoma but also variants of adenoma that are of diagnostic and clinical significance, including the ones with papillary architecture, which are often hyperfunctional and oncocytic adenomas. For the first time, there is a detailed account of the multifocal hyperplastic/neoplastic lesions that commonly occur in the clinical setting of multinodular goiter; the term thyroid follicular nodular disease (FND) achieved consensus as the best to describe this enigmatic entity. Low-risk follicular cell-derived neoplasms include non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), thyroid tumors of uncertain malignant potential, and hyalinizing trabecular tumor. Malignant follicular cell-derived neoplasms are stratified based on molecular profiles and aggressiveness. Papillary thyroid carcinomas (PTCs), with many morphological subtypes, represent the BRAF-like malignancies, whereas invasive encapsulated follicular variant PTC and follicular thyroid carcinoma represent the RAS-like malignancies. This new classification requires detailed subtyping of papillary microcarcinomas similar to their counterparts that exceed 1.0 cm and recommends not designating them as a subtype of PTC. The criteria of the tall cell subtype of PTC have been revisited. Cribriform-morular thyroid carcinoma is no longer classified as a subtype of PTC. The term "Hürthle cell" is discouraged, since it is a misnomer. Oncocytic carcinoma is discussed as a distinct entity with the clear recognition that it refers to oncocytic follicular cell-derived neoplasms (composed of > 75% oncocytic cells) that lack characteristic nuclear features of PTC (those would be oncocytic PTCs) and high-grade features (necrosis and ≥ 5 mitoses per 2 mm²). High-grade follicular cell-derived malignancies now include both the traditional poorly differentiated carcinoma as well as high-grade differentiated thyroid carcinomas, since both are characterized by increased mitotic activity and tumor necrosis without anaplastic histology and clinically behave in a similar manner. Anaplastic thyroid carcinoma remains the most undifferentiated form; squamous cell carcinoma of the thyroid is now considered as a subtype of anaplastic carcinoma. Medullary thyroid carcinomas derived from thyroid C cells retain their distinct section, and there is a separate section for mixed tumors composed of both C cells and any follicular cell-derived malignancy. A grading system for medullary thyroid carcinomas is also introduced based on mitotic count, tumor necrosis, and Ki67 labeling index. A number of unusual neoplasms that occur in the thyroid have been placed into new sections based on their cytogenesis. Mucoepidermoid carcinoma and secretory carcinoma of the salivary gland type are now included in one section classified as "salivary gland-type carcinomas of the thyroid." Thymomas, thymic carcinomas and spindle epithelial tumor with thymus-like elements are classified as "thymic tumors within the thyroid." There remain several tumors whose cell lineage is unclear, and they are listed as such; these include sclerosing mucoepidermoid carcinoma with eosinophilia and cribriform-morular thyroid carcinoma. Another important addition is thyroblastoma, an unusual embryonal tumor associated with DICER1 mutations. As in all the WHO books in the 5th edition, mesenchymal and stromal tumors, hematolymphoid neoplasms, germ cell tumors, and metastatic malignancies are discussed separately. The current classification also emphasizes the value of biomarkers that may aid diagnosis and provide prognostic information.

The Multifaceted Profile of Thyroid Disease in the Background of DICER1 Germline and Somatic Mutations: Then, Now and Future Perspectives

DICER1 protein is a member of the ribonuclease (RNAse) III family with a key role in the biogenesis of microRNAs (miRNA) and in microRNA processing, potentially affecting gene regulation at the post-transcriptional level. The role of DICER1 and its relevance to thyroid cellular processes and tumorigenesis have only recently been explored, following the acknowledgement that DICER1 germline and somatic changes can contribute not only to non-toxic multinodule goiter (MNG) lesions detected in individuals of affected families but also to a series of childhood tumours, including thyroid neoplasms, which can be identified from early infancy up until the decade of 40s. In a context of DICER1 germline gene mutation, thyroid lesions have recently been given importance, and they may represent either an index event within a syndromic context or the isolated event that may trigger a deeper and broader genomic analysis screening of individuals and their relatives, thereby preventing the consequences of a late diagnosis of malignancy. Within the syndromic context MNG is typically the most observed lesion. On the other hand, in a DICER1 somatic mutation context, malignant tumours are more common. In this review we describe the role of DICER protein, the genomic events that affect the DICER1 gene and their link to tumorigenesis as well as the frequency and pattern of benign and malignant thyroid lesions and the regulation of DICER1 within the thyroidal environment.

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.

Pan-Genomic Sequencing Reveals Actionable CDKN2A/2B Deletions and Kataegis in Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) is a lethal malignancy characterized by poor response to conventional therapies. Whole-genome sequencing (WGS) analyses of this tumor type are limited, and we therefore interrogated eight ATCs using WGS and RNA sequencing. Five out of eight cases (63%) displayed cyclin-dependent kinase inhibitor 2A (CDKN2A) abnormalities, either copy number loss (n = 4) or truncating mutations (n = 1). All four cases with loss of the CDKN2A locus (encoding p16 and p14arf) also exhibited loss of the neighboring CDKN2B gene (encoding p15ink4b), and displayed reduced CDKN2A/2B mRNA levels. Mutations in established ATC-related genes were observed, including TP53, BRAF, ARID1A, and RB1, and overrepresentation of mutations were also noted in 13 additional cancer genes. One of the more predominant mutational signatures was intimately coupled to the activity of Apolipoprotein B mRNA-editing enzyme, the catalytic polypeptide-like (APOBEC) family of cytidine deaminases implied in kataegis, a focal hypermutation phenotype, which was observed in 4/8 (50%) cases. We corroborate the roles of CDKN2A/2B in ATC development and identify kataegis as a recurrent phenomenon. Our findings pinpoint clinically relevant alterations, which may indicate response to CDK inhibitors, and focal hypermutational phenotypes that may be coupled to improved responses using immune checkpoint inhibitors.

Primary Versus Secondary Anaplastic Thyroid Carcinoma: Perspectives from Multi-institutional and Population-Level Data

Primary (or de novo) anaplastic thyroid carcinoma (ATC) is ATC without pre-existing history of differentiated thyroid carcinoma (DTC) and no co-existing DTC foci at the time of diagnosis. Secondary ATC is diagnosed if the patient had a history of DTC or co-existing DTC components at time of diagnosis. This study aimed to investigate the incidence, clinical presentations, outcomes, and genetic backgrounds of primary versus secondary ATCs. We searched for ATCs in our institutional databases and the Surveillance, Epidemiology, and End Result (SEER) database. We also performed a systematic review and meta-analysis to analyze the genetic alterations of primary and secondary ATCs. From our multi-institutional database, 22 primary and 23 secondary ATCs were retrieved. We also identified 620 and 24 primary and secondary ATCs in the SEER database, respectively. Compared to primary ATCs, secondary ATCs were not statistically different in terms of demographic, clinical manifestations, and patient survival. The only clinical discrepancy between the two groups was a significantly larger tumor diameter of the primary ATCs. The prevalence of TERT promoter, PIK3CA, and TP53 mutations was comparable between the two subtypes. In comparison to primary ATCs, however, BRAF mutations were more prevalent (OR = 4.70; 95% CI = 2.84-7.78) whereas RAS mutations were less frequent (OR = 0.43; 95% CI = 0.21-0.85) in secondary tumors. In summary, our results indicated that de novo and secondary ATCs might share many potential developmental steps, but there are other factors that suggest distinct developmental pathways.

Whole-genome Sequencing of Follicular Thyroid Carcinomas Reveal Recurrent Mutations in MicroRNA Processing Subunit DGCR8

BACKGROUND

The genomic and transcriptomic landscape of widely invasive follicular thyroid carcinomas (wiFTCs) and Hürthle cell carcinoma (HCC) are poorly characterized, and subsets of these tumors lack information on genetic driver events.

OBJECTIVE

The aim of this study was to bridge this gap.

METHODS

We performed whole-genome and RNA sequencing and subsequent bioinformatic analyses of 11 wiFTCs and 2 HCCs with a particularly poor prognosis, and matched normal tissue.

RESULTS

All wiFTCs exhibited one or several mutations in established thyroid cancer genes, including TERT (n = 4), NRAS (n = 3), HRAS, KRAS, AKT, PTEN, PIK3CA, MUTYH, TSHR, and MEN1 (n = 1 each). MutSig2CV analysis revealed recurrent somatic mutations in FAM72D (n = 3, in 2 wiFTCs and in a single HCC), TP53 (n = 3, in 2 wiFTCs and a single HCC), and EIF1AX (n = 3), with DGCR8 (n = 2) as borderline significant. The DGCR8 mutations were recurrent p.E518K missense alterations, known to cause familial multinodular goiter via disruption of microRNA (miRNA) processing. Expression analyses showed reduced DGCR8 messenger RNA expression in FTCs in general, and the 2 DGCR8 mutants displayed a distinct miRNA profile compared to DGCR8 wild-types. Copy number analyses revealed recurrent gains on chromosomes 4, 6, and 10, and fusion gene analyses revealed 27 high-quality events. Both HCCs displayed hyperploidy, which was fairly unusual in the FTC cohort. Based on the transcriptome data, tumors amassed in 2 principal clusters.

CONCLUSION

We describe the genomic and transcriptomic landscape in wiFTCs and HCCs and identify novel recurrent mutations and copy number alterations with possible driver properties and lay the foundation for future studies.

The prevalence of DNA microsatellite instability in anaplastic thyroid carcinoma - systematic review and discussion of current therapeutic options

INTRODUCTION

Anaplastic thyroid carcinoma is a rare, rapidly progressing, highly aggressive thyroid malignancy. Responses to immune checkpoint inhibitors in mismatch repair-deficient/microsatellite instability-high tumours of other locations have shown promising results, and with the extended approval of the PD-1 receptor inhibitor pembrolizumab by the Food and Drug Administration, also anaplastic thyroid cancer (ATC) requires analysis for microsatellite instability (MSI) status.

MATERIAL AND METHODS

Systematic research for relevant literature was conducted in different databases. Prevalence, detection methods, and the potential prognostic/predictive value of MSI in view of the available targeted therapies were of special focus.

RESULTS

Selected citations revealed the prevalence of MSI in 7.4%, with mutations in the MSH2 gene (33%) being the most frequent, followed by MSH6 (25%) and MLH1 (16.7%) occurring in the following combinations: MLH1-MSH2 (8.3%), MSH2-MSH6 (8.3%), and MLH3-MSH5 (8.3%). No mutations in the PMS2 gene were reported. Sixty-six co-mutations in 9 cases were found, with TP53 (88.9%), NF1 (44.4 %), ATM (33.3%), and RB1 (33.3%) being the most frequent. No RAS mutations were noted. Survival ranged between 2.8 and 48 months, and patient age varied between 49 and 84 years. There are insufficient and heterogenous data concerning the predictive or prognostic value of mismatch repair-deficient/microsatellite instability status.

CONCLUSIONS

Tumour molecular profiling is fundamental in ATC for predictive, prognostic, as well as therapeutic reasons, and analysis of MSI status is strongly suggested because a small subgroup show the MSI signature and might profit from recently approved targeted therapies.

Co-Occurrence of Familial Non-Medullary Thyroid Cancer (FNMTC) and Hereditary Non-Polyposis Colorectal Cancer (HNPCC) Associated Tumors-A Cohort Study

Familial non-medullary thyroid cancer (FNMTC) is a form of endocrine malignancy exhibiting an autosomal dominant mode of inheritance with largely unknown germline molecular mechanism. Hereditary nonpolyposis colorectal cancer syndrome (HNPCC) is another hereditary autosomal dominant cancer syndrome which, if proven to be caused by germline mutations in mismatch repair genes (MMR)-MLHL, MSH2, MSH6, PMS2, and EPCAM-is called Lynch syndrome (LS). LS results in hereditary predisposition to a number of cancers, especially colorectal and endometrial cancers. Tumors in LS are characterized by microsatellite instability (MSI) and/or loss of MMR protein expression in immunohistochemistry (IHC). MSI is a rare event in thyroid cancer (TC), although it is known to occur in up to 2.5% of sporadic follicular TC cases. There are limited data on the role of germline MMR variants FNMTC. The goal of this study was to analyze the potential clinical and molecular association between HNPCC and FNMTC. We performed a cohort study analyzing the demographic, clinical, and pathologic data of 43 kindreds encompassing 383 participants (104 affected, 279 unaffected), aged 43.5 [7-99] years with FNMTC, and performed high-throughput whole-exome sequencing (WES) of peripheral blood DNA samples of selected 168 participants (54 affected by FNMTC and 114 unaffected). Total affected by thyroid cancer members per family ranged between 2 and 9 patients. FNMTC was more prevalent in women (68.3%) and characterized by a median tumor size of 1.0 [0.2-5.0] cm, multifocal growth in 44%, and gross extrathyroidal extension in 11.3%. Central neck lymph node metastases were found in 40.3% of patients at presentation, 12.9% presented with lateral neck lymph node metastases, and none had distant metastases. Family history screening revealed one Caucasian family meeting the clinical criteria for FNMTC and HNPCC, with five members affected by FNMTC and at least eight individuals reportedly unaffected by HNPCC-associated tumors. In addition, two family members were affected by melanoma. Genome Analysis Tool Kit (GATK) pipeline was used in variant analysis. Among 168 sequenced participants, a heterozygous missense variant in the MSH2 gene (rs373226409; c.2120G>A; p.Cys707Tyr) was detected exclusively in FNMTC- HNPCC- kindred. In this family, the sequencing was performed in one member affected by FNMTC, HPNCC-associated tumors and melanoma, one member affected solely by HNPCC-associated tumor, and one member with FNMTC only, as well as seven unaffected family members. The variant was present in all three affected adults, and in two unaffected children of the affected member, under the age of 18 years, and was absent in non-affected adults. This variant is predicted to be damaging/pathogenic in 17/20 in-silico models. However, immunostaining performed on the thyroid tumor tissue of two affected by FNMTC family members revealed intact nuclear expression of MSH2, and microsatellite stable status in both tumors that were tested. Although the MSH2 p.Cys707Tyr variant is rare with a minor allele frequency (MAF) of 0.00006 in Caucasians; it is more common in the South Asian population at 0.003 MAF. Therefore, the MSH2 variant observed in this family is unlikely to be an etiologic factor of thyroid cancer and a common genetic association between FNMTC and HNPCC has not yet been identified. This is the first report known to us on the co-occurrence of FNMTC and HNPCC. The co-occurrence of FNMTC and HNPCC-associated tumors is a rare event and although presented in a single family in our large FNMTC cohort, a common genetic background between the two comorbidities could not be established.

Longitudinal Genomic Evolution of Conventional Papillary Thyroid Cancer With Brain Metastasis

BACKGROUND

Brain metastasis is extremely rare but predicts dismal prognosis in papillary thyroid cancer (PTC). Dynamic evaluation of stepwise metastatic lesions was barely conducted to identify the longitudinal genomic evolution of brain metastasis in PTC.

METHOD

Chronologically resected specimen was analyzed by whole exome sequencing, including four metastatic lymph nodes (lyn 1-4) and brain metastasis lesion (BM). Phylogenetic tree was reconstructed to infer the metastatic pattern and the potential functional mutations.

RESULTS

Contrasting with lyn1, ipsilateral metastatic lesions (lyn2-4 and BM) with shared biallelic mutations of TSC2 indicated different genetic originations from multifocal tumors. Lyn 3/4, particularly lyn4 exhibited high genetic similarity with BM. Besides the similar mutational compositions and signatures, shared functional mutations (CDK4 R24C , TP53R342*) were observed in lyn3/4 and BM. Frequencies of these mutations gradually increase along with the metastasis progression. Consistently, TP53 knockout and CDK4 R24C introduction in PTC cells significantly decreased radioiodine uptake and increased metastatic ability.

CONCLUSION

Genomic mutations in CDK4 and TP53 during the tumor evolution may contribute to the lymph node and brain metastasis of PTC.

The Genomic Landscape of Thyroid Cancer Tumourigenesis and Implications for Immunotherapy

Thyroid cancer is the most prevalent endocrine malignancy that comprises mostly indolent differentiated cancers (DTCs) and less frequently aggressive poorly differentiated (PDTC) or anaplastic cancers (ATCs) with high mortality. Utilisation of next-generation sequencing (NGS) and advanced sequencing data analysis can aid in understanding the multi-step progression model in the development of thyroid cancers and their metastatic potential at a molecular level, promoting a targeted approach to further research and development of targeted treatment options including immunotherapy, especially for the aggressive variants. Tumour initiation and progression in thyroid cancer occurs through constitutional activation of the mitogen-activated protein kinase (MAPK) pathway through mutations in BRAF, RAS, mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway and/or receptor tyrosine kinase fusions/translocations, and other genetic aberrations acquired in a stepwise manner. This review provides a summary of the recent genetic aberrations implicated in the development and progression of thyroid cancer and implications for immunotherapy.

Histology-based molecular profiling improves mutation detection for advanced thyroid cancer

Advanced cancers frequently show histologic and molecular intratumoral heterogeneity. Therefore, we comprehensively characterized advanced, metastatic, radioiodine-resistant (RAIR) thyroid carcinomas at the molecular level in the context of histologic heterogeneity with the aim to identify potentially actionable mutations that may guide the use of specific tyrosine kinase inhibitor (TKI) treatment. Whole exome sequencing (WES) was applied to 29 macrodissected tissue samples of histologically heterogeneous and homogeneous areas, lymph node and lung metastases from six clinically and histologically well-characterized metastatic RAIR thyroid cancer patients with structural incomplete response to treatment. WES data were analyzed to identify potential driver mutations in oncogenic pathways, copy number alterations, microsatellite instability, mutant-allele tumor heterogeneity, and the relevance of histologic heterogeneity to molecular profiling. In addition to known driver mutations in BRAF, NRAS, EIF1AX, NCOA4-RET, and TERT, further potentially actionable drivers were identified in AKT1, ATM, E2F1, HTR2A, and MLH3. The analysis of the evolutionary history of the mutations and the reconstruction of the molecular phylogeny of the cancers show a remarkable association between histologic and molecular heterogeneity. A comprehensive molecular analysis of the primary tumor guided by histologic analysis may help to better stratify patients for precision medicine approaches. Given the association between the molecular and the histologic heterogeneity, the selection of tumor samples for molecular analysis should be based on meticulous histologic evaluation of the entire tumor.

Novel Recurrent Altered Genes in Chinese Patients With Anaplastic Thyroid Cancer

BACKGROUND

Anaplastic thyroid cancer (ATC) is a rare but lethal malignancy, and few systematic investigations on genomic profiles of ATC have been performed in Chinese patients.

METHODS

Fifty-four ATC patients in West China Hospital between 2010 to 2020 were retrospectively analyzed, while 29 patients with available samples were sequenced by whole-exome sequencing (WES). The associations between genomic alterations and clinical characteristics were statistically evaluated.

RESULTS

The median overall survival was 3.0 months in the entire cohort, which was impacted by multiple clinical features, including age, tumor size, and different treatment strategies. In the WES cohort, totally 797 nonsilent mutations were detected; the most frequently altered genes were TP53 (48%), BRAF (24%), PIK3CA (24%), and TERT promoter (21%). Although these mutations have been well-reported in previous studies, ethnic specificity was exhibited in terms of mutation frequency. Moreover, several novel significantly mutated genes were identified including RBM15 (17%), NOTCH2NL (14%), CTNNA3 (10%), and KATNAL2 (10%). WES-based copy number alteration analysis also revealed a high frequent gain of NOTCH2NL (41%), which induced its increased expression. Gene mutations and copy number alterations were enriched in phosphatidylinositol 3-kinase/AKT/mechanistic target of rapamycin (mTOR), NOTCH, and WNT pathways.

CONCLUSIONS

This study reveals shared and ethnicity-specific genomic profiles of ATC in Chinese patients and suggests NOTCH2NL may act as a novel candidate driver gene for ATC tumorigenesis.

Molecular Pathology of Poorly Differentiated and Anaplastic Thyroid Cancer: What Do Pathologists Need to Know?

The molecular characterization of poorly and anaplastic thyroid carcinomas has been greatly improved in the last years following the advent of high throughput technologies. However, with special reference to genomic data, the prevalence of reported alterations is partly affected by classification criteria. The impact of molecular pathology in these tumors is multifaceted and bears diagnostic, prognostic, and predictive implications although its use in the clinical practice is not completely assessed. Genomic profiling data claim that genetic alterations in poorly differentiated and anaplastic thyroid carcinomas include "Early" and "Late" molecular events, which are consistent with a multi-step model of progression. "Early" driver events are mostly RAS and BRAF mutations, whereas "Late" changes include above all TP53 and TERT promoter mutations, as well as dysregulation of gene involved in the cell cycle, chromatin remodeling, histone modifications, and DNA mismatch repair. Gene fusions are rare but represent relevant therapeutic targets. Epigenetic modifications are also playing a relevant role in poorly differentiated and anaplastic thyroid carcinomas, with altered regulation of either genes by methylation/deacetylation or non-coding RNAs. The biological effects of epigenetic modifications are not fully elucidated but interfere with a wide spectrum of cellular functions. From a clinical standpoint, the combination of genomic and epigenetic data shows that several molecular alterations affect druggable cellular pathways in poorly differentiated and anaplastic thyroid carcinomas, although the clinical impact of molecular typing of these tumors in terms of predictive biomarker testing is still under exploration.

DNA repair pathway activation features in follicular and papillary thyroid tumors, interrogated using 95 experimental RNA sequencing profiles

DNA repair can prevent mutations and cancer development, but it can also restore damaged tumor cells after chemo and radiation therapy. We performed RNA sequencing on 95 human pathological thyroid biosamples including 17 follicular adenomas, 23 follicular cancers, 3 medullar cancers, 51 papillary cancers and 1 poorly differentiated cancer. The gene expression profiles are annotated here with the clinical and histological diagnoses and, for papillary cancers, with BRAF gene V600E mutation status. DNA repair molecular pathway analysis showed strongly upregulated pathway activation levels for most of the differential pathways in the papillary cancer and moderately upregulated pattern in the follicular cancer, when compared to the follicular adenomas. This was observed for the BRCA1, ATM, p53, excision repair, and mismatch repair pathways. This finding was validated using independent thyroid tumor expression dataset PRJEB11591. We also analyzed gene expression patterns linked with the radioiodine resistant thyroid tumors (n = 13) and identified 871 differential genes that according to Gene Ontology analysis formed two functional groups: (i) response to topologically incorrect protein and (ii) aldo-keto reductase (NADP) activity. We also found RNA sequencing reads for two hybrid transcripts: one in-frame fusion for well-known NCOA4-RET translocation, and another frameshift fusion of ALK oncogene with a new partner ARHGAP12. The latter could probably support increased expression of truncated ALK downstream from 4th exon out of 28. Both fusions were found in papillary thyroid cancers of follicular histologic subtype with node metastases, one of them (NCOA4-RET) for the radioactive iodine resistant tumor. The differences in DNA repair activation patterns may help to improve therapy of different thyroid cancer types under investigation and the data communicated may serve for finding additional markers of radioiodine resistance.

Spatial Distribution Patterns of Clinically Relevant TERT Promoter Mutations in Follicular Thyroid Tumors of Uncertain Malignant Potential: Advantages of the Digital Droplet PCR Technique

In thyroid carcinomas, telomerase reverse transcriptase (TERT) promoter mutations C228T and C250T predict an unfavorable clinical outcome. The analysis is particularly valuable when assessing histologically equivocal follicular thyroid tumors of uncertain malignant potential (FT-UMPs). Given recent findings of TERT promoter mutational heterogeneity in thyroid cancer, we determined the frequency of this phenomenon in FT-UMPs and minimally invasive follicular thyroid carcinomas. DNA was extracted from several tissue blocks from 16 FT-UMPs as well as 10 minimally invasive follicular thyroid carcinomas, and interrogated using Sanger sequencing as well as digital droplet PCR (ddPCR). Mutational heterogeneity was observed by Sanger sequencing in four of seven (57%) FT-UMPs. In two FT-UMPs with C228T mutations, analyses of additional blocks gave wild-type results using Sanger sequencing in one or several blocks interrogated, whereas ddPCR found low-frequency C228T mutations in one of these fractions. In two additional FT-UMPs with the C228T and C250T mutation, respectively, sequencing of additional blocks revealed the opposite mutation. Moreover, in the C250T mutated area in one of these tumors, the ddPCR displayed a co-occurring C228T mutation that failed detection through Sanger sequencing. To conclude, most TERT promoter mutated FT-UMPs display mutational heterogeneity when analyzed by Sanger sequencing, thereby emphasizing the importance of the tissue sampling process. The ddPCR technique might overcome this phenomenon because of increased sensitivity and should be considered for clinical screening purposes.

Identification of Hub Genes in Anaplastic Thyroid Carcinoma: Evidence From Bioinformatics Analysis

Anaplastic thyroid carcinoma (ATC) is a rare type of thyroid cancer that results in fatal clinical outcomes; the pathogenesis of this life-threatening disease has yet to be fully elucidated. This study aims to identify the hub genes of ATC that may play key roles in ATC development and could serve as prognostic biomarkers or therapeutic targets. Two microarray datasets (GSE33630 and GSE53072) were obtained from the Gene Expression Omnibus database; these sets included 16 ATC and 49 normal thyroid samples. Differential expression analyses were performed for each dataset, and 420 genes were screened as common differentially expressed genes using the robust rank aggregation method. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were conducted to explore the potential bio-functions of these differentially expressed genes (DEGs). The terms and enriched pathways were primarily associated with cell cycle, cell adhesion, and cancer-related signaling pathways. Furthermore, a protein-protein interaction network of DEG expression products was constructed using Cytoscape. Based on the whole network, we identified 7 hub genes that included CDK1, TOP2A, CDC20, KIF11, CCNA2, NUSAP1, and KIF2C. The expression levels of these hub genes were validated using quantitative polymerase chain reaction analyses of clinical specimens. In conclusion, the present study identified several key genes that are involved in ATC development and provides novel insights into the understanding of the molecular mechanisms of ATC development.

Anaplastic thyroid carcinoma with rhabdoid phenotype: An unusual case and a comprehensive review

Anaplastic thyroid carcinoma (ATC) is a highly aggressive thyroid malignancy predominantly affecting the elderly with a fatal outcome. ATC with rhabdoid phenotype is a rare variant, with only a few cases reported in the literature to date. We herein report a case of a 44-year old female diagnosed as ATC with rhabdoid phenotype. She had a slow-growing neck mass with no gross extrathyroidal extension (ETE) or nodal/distant metastasis at presentation. Computed tomography of the neck showed a well-defined heterogeneously hypodense nodule in the right lobe of the thyroid. On cytology, a diagnosis of papillary thyroid carcinoma (PTC) with possible anaplastic transformation was made based on the presence of vague papillae with focal nuclear features of PTC and atypical pleomorphic/rhabdoid cells. The total thyroidectomy specimen showed a relatively circumscribed lesion with no gross ETE. Histopathological examination revealed sheets of rhabdoid cells with a focus of poorly differentiated thyroid carcinoma. On immunohistochemistry, rhabdoid cells were positive for AE1/AE3, focally positive for PAX8 and were negative for TTF-1, synaptophysin, desmin, myogenin, S100P, and SMA. The neck lymph nodes were non-metastatic. The patient was further treated with adjuvant radioactive iodine. Four-months post-operatively, the patient developed pulmonary metastasis which on biopsy examination revealed metastatic ATC. Apart from being a rare tumor type, this case is unusual with its presentation too; wherein, unlike described earlier in the literature the patient had a relatively mitigated clinical course with no gross ETE or nodal/distant metastatic disease. We also review the relevant literature along with this case.

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

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

Substantial intrinsic variability in chemoradiosensitivity of newly established anaplastic thyroid cancer cell-lines

Background: Well characterized human cell lines are needed for preclinical treatment studies of anaplastic thyroid cancer (ATC).Aims/Objectives: The aim was to establish, verify and characterize a panel of ATC cell lines.Material and methods: Cell lines were established from ATC fine-needle aspiration biopsies and characterized genetically and functionally regarding treatment sensitivities.Results: Eight cell lines were established in vitro and the anaplastic thyroid origin was verified. Seven of the cell lines were also grown as xenografts. The cell lines harboured complex karyotypes with modal numbers in hyperdiploid to near-pentaploid range. Five were TP53 mutated and three carried the BRAF^V600E mutation. None had rearrangements of RET. For doxorubicin, IC₅₀ ranged from 0.42 to 46 nmol/L and for paclitaxel from 1.6 to 196 nmol/L. Radiation sensitivity varied between 2.6 and 6.3 Gy. Two of the BRAF mutated cell lines displayed high sensitivity to vemurafenib, while the third was similar to the wild-type ones.Conclusions and significance: We describe a series of new ATC cell lines demonstrating large heterogeneity in the response to cytostatic drugs and the BRAF inhibitor vemurafenib. The observations are relevant to future attempts to optimize treatment combinations for ATC.

Recent Improvements in Genomic and Transcriptomic Understanding of Anaplastic and Poorly Differentiated Thyroid Cancers

Anaplastic thyroid cancer (ATC) is a lethal human cancer with a 5-year survival rate of less than 10%. Recently, its genomic and transcriptomic characteristics have been extensively elucidated over 5 years owing to advance in high throughput sequencing. These efforts have extended molecular understandings into the progression mechanisms and therapeutic vulnerabilities of aggressive thyroid cancers. In this review, we provide an overview of genomic and transcriptomic alterations in ATC and poorly-differentiated thyroid cancer, which are distinguished from differentiated thyroid cancers. Clinically relevant genomic alterations and deregulated signaling pathways will be able to shed light on more effective prevention and stratified therapeutic interventions for affected patients.

Metastatic Anaplastic Thyroid Carcinoma in Complete Remission: Morphological, Molecular, and Clinical Work-Up of a Rare Case

Anaplastic thyroid carcinoma (ATC) exhibits an exceedingly poor prognosis, and the current treatment options are, for most cases, palliative by nature. Few reports of long-time survivors exist, although in these patients, tumors often were limited to the thyroid and/or regional lymph nodes. We describe a 64-year-old male who developed a rapidly growing mass in the left thyroid lobe. A fine-needle aspiration biopsy (FNAB) was consistent with ATC, and the patient underwent preoperative combined chemo- and radiotherapy followed by a hemithyroidectomy. The ensuing histopathological investigation was consistent with ATC adjoined by an oxyphilic well-differentiated lesion, likely a Hürthle cell carcinoma. Tumor margins were negative, and no extrathyroidal extension was noted. Focused next-generation sequencing analysis of the primary tumor tissue identified a TP53 gene mutation but could not identify any potential druggable targets. Additional Sanger sequencing detected a C228T TERT promoter mutation. The tumor was found to be microsatellite stable and displayed PDL1 expression in 80% of tumor cells. Following a CT scan 1 month postoperatively, metastatic deposits were suspected in the lung as well as in the left adrenal gland, of which FNAB verified the latter. Remarkably, upon radiological follow-up, the disease had gone into apparent complete remission. The patient is alive and well with no signs of residual disease after 12 months of follow-up. We here summarize the clinical, histological, and molecular data of this highly interesting patient case and review the literature for possible common denominators with other patients with disseminated ATC.

Intratumoral Genetic Heterogeneity in Papillary Thyroid Cancer: Occurrence and Clinical Significance

Intratumoral heterogeneity (ITH) refers to a subclonal genetic diversity observed within a tumor. ITH is the consequence of genetic instability and accumulation of genetic alterations, two mechanisms involved in the progression from an early tumor stage to a more aggressive cancer. While this process is widely accepted, the ITH of early stage papillary thyroid carcinoma (PTC) is debated. By different genetic analysis, several authors reported the frequent occurrence of PTCs composed of both tumor cells with and without RET/PTC or BRAF^V600E genetic alterations. While these data, and the report of discrepancies in the genetic pattern between metastases and the primary tumor, demonstrate the existence of ITH in PTC, its extension and biological significance is debated. The ITH takes on a great significance when involves oncogenes, such as RET rearrangements and BRAF^V600E as it calls into question their role of driver genes. ITH is also predicted to play a major clinical role as it could have a significant impact on prognosis and on the response to targeted therapy. In this review, we analyzed several data indicating that ITH is not a marginal event, occurring in PTC at any step of development, and suggesting the existence of unknown genetic or epigenetic alterations that still need to be identified.