MicroRNA expression profile helps to distinguish benign nodules from papillary thyroid carcinomas starting from cells of fine-needle aspiration

Approach to Thyroid Nodules: Diagnosis and Treatment

Thyroid nodules (TNs) are prevalent and found in up to 50% of individuals. While most TNs are benign, some can be malignant. The evaluation of TNs is crucial to rule out malignancy and identify those requiring surgical intervention. This study aimed to clarify the reported prevalence of TNs, focusing specifically on their various types, assessment and diagnostic processes, current evaluation methods, and evidence-based management. It also provides recommendations for follow-up. TNs are typically found during physical exams or incidentally during imaging procedures. Routine laboratory and clinical evaluations of TNs are common. Ultrasound is the preferred imaging method to determine if a TN needs a biopsy. Fine-needle aspiration (FNA) is crucial in deciding whether surgery or surveillance is necessary. TNs that show suspicious features on the ultrasound may require cytologic analysis to assess the risk of malignancy. The effectiveness of several supplementary molecular tests is still uncertain, although some studies report promising results. The management and treatment approach for TNs primarily depends on the results of FNA cytology and ultrasound characteristics. The optimal treatment strategy for TNs ranges from straightforward follow-ups for low-risk cases to surgical intervention for high-risk patients. Rather than adopting a uniform approach, clinicians should assess each patient on a case-by-case basis using current knowledge and a collaborative, multidisciplinary method.

Effective Use of microRNA, BRAF and Sonographic Risk Assessment in Bethesda III Thyroid Nodules Requires a Different Approach to Nodules with Features of Nuclear Atypia and Other Types of Atypia

The aim of the study was to analyze the diagnostic usefulness of the combined assessment of the ultrasound risk category of the nodule (evaluated with EU-TIRADS system), the presence of BRAF V600E mutation and the expression of selected microRNAs (miR-146b, miR-221 and miR-222) in Bethesda category III thyroid nodules, separately for cases with nuclear atypia (AUS-nuclear) and cases with other types of atypia (AUS-other). We evaluated 161 nodules (66 AUS-nuclear and 95 AUS-other) with known results of postoperative histopathological examination. The rate of cancer and the rate of PTC among cancers were nearly three times higher in the AUS-nuclear than the AUS-other group. For AUS-nuclear nodules, the most effective diagnostic panel included, in addition to repeat FNA, the assessment of BRAF V600E mutation and the expression of miR-146b and miR-222 (sensitivity: 93.5%, specificity: 80.0%). For AUS-other nodules, a two-step procedure was most effective: at the first stage, forgoing surgical treatment in subjects with a benign repeat FNA outcome, and, at the second stage, the assessment of miR-222 expression and the EU-TIRADS category (sensitivity: 92.3%, specificity: 76.8%). The optimal use of molecular methods in the diagnostics of category III thyroid nodules requires a separate approach for nodules with nuclear atypia and nodules with other types of atypia.

Chromatin-Accessible miRNA Regulons Driving Thyroid Tumorigenesis and Progression

BACKGROUND

Although papillary thyroid cancer can remain indolent, associated lymph node metastases and recurrence rates are approximately 50% and 20%, respectively. Omics-based medicine has led to the discovery of predictive biomarkers that can be used to predict tumor progression and clinical outcomes. We aimed to develop a noninvasive omics-driven blood test to allow accurate risk stratification and help tailor individual patient treatment plans.

STUDY DESIGN

RNA sequencing (seq) and microRNA analysis of The Cancer Genome Atlas and Gene Expression Omnibus datasets were employed to identify an epigenetic prognostic panel. Integrated bulk assay for transposase-accessible chromatin-seq and RNA-seq experiments confirmed the results. Sixty-two paired tumor and adjacent control thyroid tissues and 67 blood samples (62 papillary thyroid cancer and 5 controls) were analyzed for validation using sequencing and real-time polymerase chain reaction and correlated to clinical outcomes. A liposome-exosome fusion clustered regularly interspaced short palindromic repeats (CRISPR)-fluorescent detection system miRNA assay was developed. A predictive risk nomogram was generated and tested for performance.

RESULTS

Our miRNA panel (miR-146b-5p and miR-221-3p) from tissue and blood was associated with aggressive features and was located within accessible chromatin regions. The miRNA risk score and prognostic nomogram showed higher accuracy in predicting lymph node metastases (miR-146b: area under the curve [AUC] 0.816, sensitivity 76.9%; miR-221: AUC 0.740, sensitivity 79.5%) and recurrence (miR-146b: AUC 0.921, sensitivity 75.0%; miR-221: AUC 0.756, sensitivity 70.0%; p < 0.001) than staging and American Thyroid Association risk stratification. CRISPR-based miRNA assays showed upregulation in the blood of cancer cohorts.

CONCLUSIONS

CRISPR-based detection of miR-146b and miR-221 in the blood of thyroid cancer patients is a reliable and noninvasive tool for real-time assessment and prognostication that has great potential to provide a direct impact on the care of these patients.

An institutional experience with DICER1 mutated thyroid nodules-evaluating the cytomorphology and molecular phenotype

INTRODUCTION

DICER1 mutated thyroid nodules are commonly seen in pediatric populations often, as part of DICER1 syndrome. We seek to evaluate DICER1 mutated thyroid nodules in adult populations to assess whether there exists distinctive clinical, cytologic, histologic, and molecular characteristics that underline our institutional cohort.

MATERIALS AND METHODS

Retrospective analysis was performed on all fine-needle aspiration (FNA) specimens with a corresponding ThyroSeq panel, to select a cohort of cases with DICER1 mutations. Clinical, radiologic, and cytology materials were reviewed, and histology was reviewed for corresponding resection cases were available. ThyroSeq panel was further scrutinized for additional molecular alterations and variant allele frequency.

RESULTS

DICER1 mutated thyroid nodules (n = 8), more commonly occurred in younger adults (P = 0.01) with larger (P = 0.01) nodules and only in female patients in our cohort. FNA commonly demonstrates cellular specimens with banal cytomorphologic cues including regular nuclei, inconspicuous nucleoli, smooth nuclear membranes, and abundant colloid. On retrospective review by 2 cytopathologists, the lesions were frequently diagnosed as Bethesda II (5 of 8) by both reviewers. Histology, when available, showed that all nodules were categorized as follicular adenomas (5 of 5), often demonstrating macrofollicles with papillary excrescences demonstrating bland nuclei (4 of 5). DICER1 mutational profile revealed a variant allele frequency of &gt;40% in 25% of cases (2 of 8) and &gt;30% in an additional 4 cases, highlighting a possible germline association.

CONCLUSIONS

DICER1 mutated nodules may be under-reported due to banal cytomorphologic features and may be associated with an underlying germline alteration.

hsa-miR-206b Involves in the Development of Papillary Thyroid Carcinoma via Targeting LMX1B

Objectives

Papillary thyroid carcinoma (PTC) is the most common endocrine system malignant thyroid cancer, and patients with lymph node metastasis typically exhibit poor prognosis. MicroRNAs (miRNAs) can act as either oncogenes or tumor suppressors in PTC. This study was aimed at using PTC transcriptome data obtained from The Cancer Genome Atlas (TCGA) to identify differentially expressed, survival-related miRNAs and target genes.

Methods

We analyzed the TCGA datasets to identify differentially expressed mRNAs/miRNAs in 493 PTC patients with stage I_II group (stages I and II) versus stage III_IV group (stages III and IV) according to TNM staging. The Kaplan-Meier survival analysis, the Cox regression analysis, and the log-rank test were performed to investigate survival-related miRNAs.

Results

We identified 36 significantly differentially expressed miRNAs in the stage I_II group versus the stage III_IV group, in which 31 were upregulated and only 5 were downregulated (i.e., hsa-miR-891a-5p, hsa-miR-892a, hsa-miR-888-5p, hsa-miR-891b, and hsa-miR-892b). Additionally, five signature miRNAs (hsa-miR-206, hsa-miR-299-3p, hsa-miR-299-5p, hsa-miR-496, and hsa-miR-509-3-5p) were associated with the overall survival of PTC patients. We also found that LMX1B, whose expression was inversely correlated with hsa-miR-206 expression, was a putative target gene of hsa-miR-206 and LMX1B was likely to serve as a tumor suppressor in PTC.

Conclusion

hsa-miR-206b might be involved in promoting TNM staging in PTC via targeting of LMX1B.

Molecular Characterization of Thyroid Follicular Lesions in the Era of "Next-Generation" Techniques

It is unequivocally recognized that thyroid nodules are frequently detected in the adult population and mostly characterized by benign lesions (up to 70% of them), with only 5%-15% malignant lesions. The evaluation of thyroid lesions with fine-needle aspiration cytology (FNAC) represents one of the first and most useful diagnostic tools in the definition of their nature. Despite the fact that the majority of thyroid lesions are correctly diagnosed as either benign (70%-75%) or malignant (5%-10%) entities, the remaining nodules (20%-25%) represent the "gray zone" of follicular lesions, which belong to indeterminate categories, according to the different classification systems. This indeterminate group of lesions includes both benign and malignant entities, which cannot be easily discriminate with morphology alone. In these last decades, the increasing role of molecular testings, feasibly performed on cytological material combined with the discoveries of specific genetic alterations in the field of thyroid pathology, has opened the pace to their more accurate and specific contribution on cytology. In fact, in 2015, in the revised management guidelines for patients with thyroid nodules and well-differentiated thyroid cancers (WDTCs), the American Thyroid Association (ATA) confirmed the performance of molecular testing in thyroid indeterminate cytology, and the same performance was addressed in recent update of the management of thyroid nodules in the second edition of the Bethesda system for reporting thyroid cytopathology (TBSRTC). In the current review, we discuss the role of molecular tests for the different thyroid diagnostic categories of the Bethesda system for reporting thyroid cytopathology, mostly focusing our attention on the follicular and indeterminate lesions.

MicroRNA-Based Risk Score for Predicting Tumor Progression Following Radioactive Iodine Ablation in Well-Differentiated Thyroid Cancer Patients: A Propensity-Score Matched Analysis

Simple Summary

The three-tiered American Thyroid Association (ATA) risk stratification helps clinicians tailor decisions regarding follow-up modalities and the need for postoperative radioactive iodine (RAI) ablation and radiotherapy. However, a significant number of well-differentiated thyroid cancers (DTC) progress after treatment. Current follow-up modalities have also been proposed to detect disease relapse and recurrence but have failed to be sufficiently sensitive or specific to detect, monitor, or determine progression. Therefore, we assessed the predictive accuracy of the microRNA-based risk score in DTC with and without postoperative RAI. We confirm the prognostic role of triad biomarkers (miR-2f04, miR-221, and miR-222) with higher sensitivity and specificity for predicting disease progression than the ATA risk score. Compared to indolent tumors, a higher risk score was found in progressive samples and was associated with shorter survival. Consequently, our prognostic microRNA signature and nomogram provide a clinically practical and reliable ancillary measure to determine the prognosis of DTC patients.

Abstract

To identify molecular markers that can accurately predict aggressive tumor behavior at the time of surgery, a propensity-matching score analysis of archived specimens yielded two similar datasets of DTC patients (with and without RAI). Bioinformatically selected microRNAs were quantified by qRT-PCR. The risk score was generated using Cox regression and assessed using ROC, C-statistic, and Brier-score. A predictive Bayesian nomogram was established. External validation was performed, and causal network analysis was generated. Within the eight-year follow-up period, progression was reported in 51.5% of cases; of these, 48.6% had the T1a/b stage. Analysis showed upregulation of miR-221-3p and miR-222-3p and downregulation of miR-204-5p in 68 paired cancer tissues (p < 0.001). These three miRNAs were not differentially expressed in RAI and non-RAI groups. The ATA risk score showed poor discriminative ability (AUC = 0.518, p = 0.80). In contrast, the microRNA-based risk score showed high accuracy in predicting tumor progression in the whole cohorts (median = 1.87 vs. 0.39, AUC = 0.944) and RAI group (2.23 vs. 0.37, AUC = 0.979) at the cutoff >0.86 (92.6% accuracy, 88.6% sensitivity, 97% specificity) in the whole cohorts (C-statistics = 0.943/Brier = 0.083) and RAI subgroup (C-statistic = 0.978/Brier = 0.049). The high-score group had a three-fold increased progression risk (hazard ratio = 2.71, 95%CI = 1.86–3.96, p < 0.001) and shorter survival times (17.3 vs. 70.79 months, p < 0.001). Our prognostic microRNA signature and nomogram showed excellent predictive accuracy for progression-free survival in DTC.

Thyroid and Molecular Testing. Advances in Thyroid Molecular Cytopathology

Thyroid nodules are a common finding in the adult population including the fact that more than 50% of individuals, over the age of 60, have thyroid nodules. The majority have been mostly detected with ultrasonography and 10% by palpation. The majority of these nodules are benign, whereas 5–15% of them are malignant. The pre-operative diagnosis of cancer is a critical challenge in order to ensure that each patient can be treated with the best tailored management with a reduction of unnecessary surgery for benign lesions. Fine needle aspiration cytology (FNAC) represents the first and most important diagnostic tool for the evaluation of thyroid lesions. According to the literature, FNAC is able to render a conclusive diagnosis in up to 70–80% of all cases. For the remaining 20–30% of nodules, cytological diagnoses fall into the category of indeterminate lesions mostly due to the lack of specific morphological features. According to the Bethesda system for reporting thyroid cytopathology (TBSRTC), indeterminate lesions can be sub-stratified into three different subcategories including “atypia of undetermined significance/follicular lesion of undetermined significance-AUS/FLUS”; “follicular or Hürthle cell neoplasm/suspicious for follicular or Hürthle cell neoplasm-FN/SFN”; and “suspicious for malignancy-SFM”. Many of these indeterminate lesions undergo repetition or diagnostic lobectomy. Nonetheless, the majority of these cases will have a benign diagnosis due to the fact that the rate of cancer ranges between 6 and 30%. It stands to reason that the application of ancillary technique, mostly molecular testing, emerged as a critical additional tool for those thyroid indeterminate lesions. Since the early 1990s, material collected from cytological samples yields sufficient and adequate cells for the detection of point mutation or gene fusions. Nonetheless, the further availability of new sequencing technologies such as next-generation sequencing (NGS) has led to more comprehensive molecular applications adopted now in clinical use. The current review investigates the multiple advances in the field of molecular testing applied in thyroid cytology.

Different stability of miRNAs and endogenous control genes in archival specimens of papillary thyroid carcinoma

BACKGROUND

The most popular miRNA quantitation technique is RQ-PCR with relative gene expression method that requires an endogenous control (EC) gene for data normalization. However, there are insufficient data and selection criteria on the most suitable ECs for miRNA expression studies in many cancer types including papillary thyroid carcinoma (PTC). Therefore, in this study we evaluated the impact of chosen EC and archival formalin-fixed, paraffin-embedded (FFPE) PTC tissue age on estimated target miRNA expression.

METHODS

RQ-PCR was used to determine expression levels of five miRNAs (miR-146b, miR-222, miR-21, miR-221 and miR-181b) and three different endogenous controls (RNU48, let-7a, miR-16), which were used to normalize the data. In total, 400 FFPE PTC tissues were analyzed that have been stored from 1 to 15 years.

RESULTS

The stability of commonly used ECs RNU48 and let-7a significantly differs from the stability of target miRNA in archival FFPE PTC tissues. Moreover, these differences have a great impact on miRNA expression results when FFPE tissue samples have been stored for a different period of time.

CONCLUSIONS

It is important to select an ECs not only stable in the tissue of interest but also with similar stability to target miRNA, especially when working with samples of different age.

Genetic alterations in cfDNA of benign and malignant thyroid nodules based on amplicon-based next-generation sequencing

Background

Circulating cell-free DNA (cfDNA) serves as a biomarker in multiple malignant diseases. However, controversy still surrounds the role of cfDNA detection in the diagnosis and monitoring of papillary thyroid carcinoma (PTC). This study set out to identify the role of cfDNA detection in distinguishing between benign and malignant thyroid nodules.

Methods

Tissue, blood cell, and plasma samples were collected from 10 patients with benign nodules and 10 patients with malignant nodules. The DNA isolated from these samples was subject to PCR-based amplification using primers designed for 50 proto-oncogenes and tumor suppressor genes. PCR products were sequenced using Illumina technology, and the mutations were detected with varScan among sequencing data for each sample and comparative analysis was carried out.

Results

Through amplicon sequencing, we found one non-synonymous somatic mutation in the benign nodules and three in the malignant nodules. Among these four mutations, BRAF^V600E mutation was detected in the tissue samples of 8 out of the 10 PTC patients, but it was not detected in the benign nodules. However, no BRAF^V600E mutation was detected in cfDNA. Further differential analysis of cfDNA indicated that some genes had more mutations in benign patients than in malignant patients, such as MET and IDH, and some genes had more mutations in malignant patients, such as PIK3CA and EZH2.

Conclusions

We found that BRAF^V600E mutation was a credible disease-related mutation in PTC; however, it could not be detected in cfDNA. Moreover, there was a large difference in mutation gene distribution between benign and malignant thyroid nodules.

The Prognostic Value of MicroRNAs in Thyroid Cancers-A Systematic Review and Meta-Analysis

Thyroid cancer (TC) includes various phenotypes, from indolent to highly aggressive cancer. The limitations of the current prognostication systems to predict the recurrence risk and the variability in expression of the genes involved in the thyroid carcinogenesis uncover the need for new prognostic biomarkers by taking into account potential epigenetic differences. We aimed to summarize the current knowledge regarding the prognostic impact of microRNAs (miRNAs) in TC. A literature search was conducted in PubMed, Embase, Scopus, and Web of Science databases. Both upregulated and downregulated miRNAs are significantly correlated with worse overall survival (hazard ratio (HR) = 5.94, 95% CI: 2.73-12.90, p < 0.001; HR = 0.51, 95% CI: 0.26-0.96, p = 0.048) disease/recurrence-free survival (HR = 1.58, 95% CI: 1.08-2.32, p = 0.003; HR = 0.37, 95%, CI: 0.24-0.60, p < 0.001). Sensitivity analysis revealed a significant association between the higher expression of miR-146b, miR-221, and miR-222 and the recurrence of papillary TC (OR = 9.11, 95% CI 3.00 to 27.52; p < 0.001; OR = 3.88, 95% CI 1.34 to 11.19, p < 0.001; OR = 6.56, 95% CI 2.75 to 15.64, p < 0.001). This research identified that miR-146b, miR-221, and miR-222 could serve as potential prognostic biomarkers in TC, particularly in PTC. Further studies are needed to strengthen these findings and sustain its clinical applicability.

Differential MicroRNA-Signatures in Thyroid Cancer Subtypes

Thyroid cancer is one of the most common endocrine cancers, with an increasing trend in the last few decades. Although papillary thyroid cancer is the most frequent subtype compared with follicular or anaplastic thyroid cancer, it can dedifferentiate to a more aggressive phenotype, and the recurrence rate is high. The cells of follicular adenomas and follicular carcinomas appear identical in cytology, making the preoperative diagnosis difficult. On the other hand, anaplastic thyroid cancer poses a significant clinical challenge due to its aggressive nature with no effective therapeutic options. In the past several years, the roles of genetic alterations of thyroid tumors have been documented, with a remarkable correlation between genotype and phenotype, indicating that distinct molecular changes are associated with a multistep tumorigenic process. Besides mRNA expression profiles, small noncoding microRNA (miRNA) expression also showed critical functions for cell differentiation, proliferation, angiogenesis, and resistance to apoptosis and finally activating invasion and metastasis in cancer. Several high-throughput sequencing studies demonstrate that miRNA expression signatures contribute clinically relevant information including types of thyroid cancer, tumor grade, and prognosis. This review summarizes recent findings on miRNA signatures in thyroid cancer subtypes.

Association of MicroRNA Expression and BRAFV600E Mutation with Recurrence of Thyroid Cancer

Many miRNAs and cancer-related mutations have been proposed as promising molecular markers of papillary thyroid carcinoma (PTC). However, there are limited data on the correlation between miRNA expression, BRAFV600E mutation, and PTC recurrence. Therefore, to evaluate the potential of BRAFV600E mutation and five selected miRNAs (-146b, -222, -21, -221, -181b) in predicting PTC recurrence, these molecular markers were analyzed in 400 formalin-fixed, paraffin-embedded PTC tissue specimens. The expression levels of miRNAs were measured using qRT-PCR. It was demonstrated that expression levels of all analyzed miRNAs are significantly higher in recurrent PTC than in non-recurrent PTC (p < 0.05). Moreover, higher expression levels of miR-146b, miR-222, miR-21, and miR-221 were associated with other clinicopathologic features of PTC, such as tumor size and lymph node metastases at initial surgery (p < 0.05). No significant differences in the frequency of BRAFV600E mutation in recurrent PTC and non-recurrent PTC were determined. Our results suggest that miRNA expression profile differs in PTC that is prone to recurrence when compared to PTC that does not reoccur after the initial surgery while BRAFV600E mutation frequency does not reflect the PTC recurrence status. However, the prognostic value of the analyzed miRNAs is rather limited in individual cases as the pattern of miRNA expression is highly overlapping between recurrent and non-recurrent PTC.

Overexpression of mir-129-1, miR-146b, mir-183, and mir-197 in follicular thyroid carcinoma and adenoma tissues

Follicular thyroid carcinoma (FTC) is responsible for approximately 10% of thyroid malignancies. Since this type of malignancy indicates no capsular and vascular invasions, adenoma and follicular carcinoma of thyroid are not distinguishable. It has been proved that microRNAs, which regulate approximately 30% of coding proteins, have an association with follicular thyroid adenoma (FTA) and carcinoma of the thyroid. Therefore, the aim of this study was to assess the expression of some miRNAs for detecting the most appropriate miRNA as potential biomarker in the diagnosis of FTA and FTC patients. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was applied to determine the expression levels of miR-129-1, miR-146b,-183 and miR-197 in 48 cases (16 FTC, 16 FTA and 16 hyperplasia/multinodular goiter (MNG) cases). The significance of miRNA differential expression levels among groups were assessed using Multivariate test by Statistical Package for Science Software (SPSS v.20) and Graph Pad Prism v.8. Results indicated that all of the miRNAs had significant overexpression in FTC and FTA versus MNG cases, and also increased expression level in FTC in comparison with FTA, however it was not significant. The results of ROC curve analysis determined the significant overexpression and prognostic value of miR-129-1 in FTA cases and miR-146b in both FTA and FTC cases compared to MNG group. Although all of the earlier mentioned microRNAs were overexpressed in FTC and FTA cases, the ROC curve results demonstrated that miR-129-1 had agreeable AUC for FTA cases. Therefore, it seems that it's cut-off point could be helpful in distinguishing between FTA and multinodular goiter cases. On the other hand, although miR-146b has excellent diagnostic value in both FTA and FTC groups, it seems that this microRNA is unable to act as a specific biomarker to discriminate between FTA and FTC cases. This data need to be confirmed in a large cohort study and other biological samples such as plasma.

Ancillary molecular testing of indeterminate thyroid nodules

Cytological specimens from thyroid nodules are increasingly being adopted as the first available material for cost effectively managing patients in the era of personalized medicine. Cytology aspirates not only play a central role in providing accurate diagnoses, but are also being collected for ancillary molecular testing. Molecular analysis, including the evaluation of somatic mutations and other genomic alterations, has accordingly become well integrated in the cytological workup of thyroid lesions. Appropriately handled thyroid cytology preparations provide well-preserved and adequately cellular material with improved DNA/RNA quantity. The recent publication of the 2nd edition of The Bethesda System for Reporting Thyroid Cytopathology and the American Thyroid Association guidelines confirm the relevant role of molecular testing in the management of the different subcategories of indeterminate thyroid lesions. This review discusses the role of molecular testing for indeterminate thyroid nodules, including the recent introduction of the noninvasive, encapsulated follicular variant of papillary thyroid carcinoma (FVPTC), known also as noninvasive follicular neoplasm with papillary-like nuclear features (NIFTP).

The Role of Molecular Testing for the Indeterminate Thyroid FNA

Thyroid nodules are common in the adult population where a majority are benign and only 4.0% to 6.5% are malignant. Fine needle aspiration (FNA) is a key method used in the early stages to evaluate and triage patients with thyroid nodules. While a definitive cytological diagnosis is provided in more than 70–75% of all thyroid FNA cases, the group of indeterminate lesions offers a challenge in terms of interpretation and clinical management. Molecular testing platforms have been developed, are recognized as an option by the 2015 American Thyroid Association Guidelines, and are frequently used in conjunction with FNA as an integral part of the cytologic evaluation. In this review, the utility of molecular testing options for nodules assigned to the group of indeterminate thyroid FNAs is described.

Update on Molecular Testing for Cytologically Indeterminate Thyroid Nodules

Fine needle aspiration biopsy (FNAB) and ultrasonography are the most common modalities for the diagnosis and follow up of thyroid nodules. FNAB is able to distinguish benign from malignant nodules with high sensitivity and specificity; however, 20% to 30% of nodules are diagnosed as indeterminate with a risk of malignancy varying from 10% to 75% based on the 2017 revision of the Bethesda System for Reporting Thyroid Cytopathology. Molecular tests are being increasingly used to triage this group of nodules. Several molecular tests are commercially available and newer upgrades are being developed to either "rule in" or "rule out" malignancy with greater accuracy. The Afirma gene expression classifier and its recent upgrade (the Afirma gene sequencing classifier), Thryoseq v2, a next generation sequencing test and its recent upgrade (the v3), RosettaGX Reveal based on microRNA alterations, and ThyGenX/ThyraMIR, a combination test, are currently on the market. Familiarity with these tests, their performance, and postvalidation publications will enable appropriate test selection and improve triage of patients for appropriate therapy. The underlying rate of malignancy at different institutions and the interobserver variability in cytologic and histologic diagnosis of thyroid lesions are important factors that impact the performance of the various molecular tests.

To Obtain More With Less: Cytologic Samples With Ancillary Molecular Techniques-The Useful Role of Liquid-Based Cytology

CONTEXT

- Fine-needle aspiration cytology has been increasingly used as the first tool in the evaluation of several diseases. Although cytology has a relevant role in the discrimination between benign and malignant lesions, conventional slides cannot lead to 100% conclusive results. It was hoped that the introduction of liquid-based cytology (LBC) would improve the efficacy of cytology through standardization, quality improvement, and the possibility of carrying out ancillary techniques on the residual stored material. In recent decades, the application of genomic alterations has been studied on cytologic samples with feasible and reliable results. The molecular analysis offers a powerful aid to define the best clinical or surgical approaches and follow-up for patients. In recent years, the application of different ancillary techniques has been carried out on conventional slides even though LBC represents a useful additional and alternative method for molecular testing.

OBJECTIVE

- To demonstrate the relevance of LBC as a valid aid to overcoming the difficulties encountered in the application of ancillary techniques on conventional slides.

DATA SOURCES

- We examined and reviewed our experience with the application of ancillary techniques on LBC performed on different body sites.

CONCLUSIONS

- We emphasize that LBC achieves significant and accurate results. It represents a valid method for cytologic evaluation and it provides highly reproducible and informative molecular yields.

A three plasma microRNA signature for papillary thyroid carcinoma diagnosis in Chinese patients

Whether plasma miRNAs could be used as novel non-invasive biomarkers in diagnosing papillary thyroid carcinoma (PTC) remains unknown. In this study, we designed a four-phase study to identify differentially expressed plasma miRNAs in Chinese PTC patients. Exiqon panel was initially utilized to conduct plasma miRNA profile (3 PTC pools VS. 1 healthy control (HC) pool; each 10 samples were pooled as 1 sample). The dysregulated miRNAs were then analyzed in the training (30 PTC VS. 30 HCs), testing (57 PTC VS. 54 HCs) and external validation phases (33 PTC VS. 30HCs). The identified miRNAs were further affirmed in benign nodules (2 nodular goiter (NG) pool VS. 1 HC pool). We also verified the expression of identified miRNAs in 17 matched malignant and normal tissue samples, NG plasma samples (29 PTC VS. 29 NG) and plasma exosomes (25 PTC VS. 25 HCs). Receiver operating characteristic (ROC) curves were constructed to evaluate the diagnostic value of the identified miRNAs. As a result, the screening phase demonstrated 30 dysregulated plasma miRNAs in PTC patients compared with HCs. After multiphase experiment processes, miR-346, miR-10a-5p and miR-34a-5p were found significantly elevated in PTC plasma samples relative to HCs. The areas under the ROC curve (AUC) of the three-miRNA panel for the training, testing and validation phases were 0.926, 0.811 and 0.816, separately. The panel could also differentiate PTC from NG with the AUC of 0.877. MiR-346 and miR-34a-5p but not miR-10a-5p were up-regulated in PTC tissues. And the three miRNAs showed consistently up-regulation in PTC plasma exosomes. In conclusion, our study established a three-miRNA panel in plasma with considerable clinical value in discriminating PTC from HC or NG.

MicroRNA expression profile of thyroid nodules in fine-needle aspiration cytology: a confirmatory series

INTRODUCTION

MiRNAs are small endogenous non-coding RNAs implicated with gene expression regulation. Changes in miRNA levels have been reported in thyroid cancer. Fine-needle aspiration cytology (FNAC) is the most reliable tool for differential diagnosis of thyroid nodules.

METHODS

We have analyzed 174 FNAC from 168 patients with thyroid nodules for expression levels of 11 miRNAs (miRNA197; -187; -181b-3p; -181b-5p; -224; -181a; 146b; -221; -222; -155 and miRNA183) known to be up-regulated in cancer tissues compared to benign lesions. Expression of miRNAs was analyzed in FNA samples calculating the fold change of miRNA expression relative to normal thyroid tissue after normalization to an endogenous control.

RESULTS

In FNAC, miRNA expression was confirmed to be higher in malignant or suspicious for malignancy nodules compared to benign, only for miRNA146b, -222 and -221 (fold change expression ≥ 5).

CONCLUSION

In this study, we confirmed that a limited set of miRNAs can be used for the differential diagnosis of thyroid nodules.

Small RNA sequencing of sessile serrated polyps identifies microRNA profile associated with colon cancer

Sessile serrated adenoma/polyps (SSA/Ps) of the colon account for 20-30% of all colon cancers. Small non-coding RNAs, including microRNAs (miRNAs), may function as oncogenes or tumor suppressor genes involved in cancer development. Small RNA sequencing (RNA-seq) was used to characterize miRNA profiles in SSA/Ps, hyperplastic polyps (HPs), adenomatous polyps and paired uninvolved colon. Our 108 small RNA-seq samples' results were compared to small RNA-seq data from 212 colon cancers from the Cancer Genome Atlas. Twenty-three and six miRNAs were differentially expressed in SSA/Ps compared to paired uninvolved colon and HPs, respectively. Differential expression of MIR31-5p, MIR135B-5p and MIR378A-5p was confirmed by RT-qPCR. SSA/P-specific miRNAs are similarly expressed in colon cancers containing genomic aberrations described in serrated cancers. Correlation of miRNA expression with consensus molecular subtypes suggests more than one subtype is associated with the serrated neoplasia pathway. Canonical pathway analysis suggests many of these miRNAs target growth factor signaling pathways.

Current Standards and Recent Advances in Biomarkers of Major Endocrine Tumors

The complexity of endocrine tumor diagnosis stems from its variable symptoms and presentation that may mimic many other disease states, or display asymptomatic properties for a prolonged amount of time. Early and accurate disease identification is needed for better patient prognosis. The key to this may be in using validated biomarkers with enhanced sensitivity and specificity. Several biomarkers are consistently used across various endocrine tumor types, possibly indicating a deeper pathophysiological mechanism behind endocrine cancer genesis and development. For example, carbohydrate antigen (CA) is measured in both pancreatic adenocarcinoma as well as ovarian cancer for diagnosis, surveillance, and risk stratification. The discovery of measuring miRNAs that are highly expressed in malignant tumors is also a novel strategy across multiple endocrine tumor types, and is propelling the future advancement of biomarker development. This review introduces currently utilized biomarkers in some of the commonly known endocrine tumors, including thyroid, adrenal, pituitary, pancreatic, and gonadal carcinoma, as well as future research directions.

MiRNA-221/222 in thyroid cancer: A meta-analysis

OBJECTIVES

A meta-analysis was performed to observe whether a difference in miRNA-221/222 expression exists in thyroid cancer with normal thyroid or BTLs (benign thyroid lesions) and, under this premise, assess its diagnostic efficacy for thyroid cancer.

METHODS

Systematic electronic literature searches were conducted to include PubMed, the Cochrane Central Register of Controlled Trials, and Web of Science. The combined fold change (FC) was calculated, and pooled estimates of sensitivity, specificity, diagnostic odds ratio (DOR) and summary receiver operating characteristic (SROC) curves were calculated.

RESULTS

Twenty-seven articles were included in this meta-analysis. The combined FC of miRNA-221/222 were 13.85 and 13.75 in thyroid cancer with normal control. For miRNA-221/222, the pooled sensitivity was 0.79 (95% CI = 0.73-0.85), specificity was 0.84 (95% CI = 0.76-0.90) and AUC (area under the curve) value was 0.88 (0.85-0.91). For miRNA-221, the pooled sensitivity was 0.82 (95% CI = 0.76-0.86) and specificity was 0.84 (95%CI = 0.74-0.91). For miRNA-222, the pooled sensitivity was 0.78 (95%CI = 0.68-0.85) and specificity was 0.83 (95% CI = 0.70-0.92).

CONCLUSION

Differences in expression levels of miRNA-221/222 can provide clues for exploring the etiology of thyroid cancer. In addition, miRNA-221/222 were promising molecular biomarkers that may significantly improve the diagnostic accuracy of thyroid cancer.

Morphology combined with ancillary techniques: An algorithm approach for thyroid nodules

INTRODUCTION

Several authors have underlined the limits of morphological analysis mostly in the diagnosis of follicular neoplasms (FN). The application of ancillary techniques, including immunocytochemistry (ICC) and molecular testing, contributes to a better definition of the risk of malignancy (ROM) and management of FN. According to literature, the application of models, including the evaluation of ICC, somatic mutations (ie, BRAF^V600E ), micro RNA analysis is proposed for FNs. This study discusses the validation of a diagnostic algorithm in FN with a special focus on the role of morphology then followed by ancillary techniques.

METHODS

From June 2014 to January 2016, we enrolled 37 FNs with histological follow-up. In the same reference period, 20 benign nodules and 20 positive for malignancy were selected as control. ICC, BRAF^V600E mutation and miR-375 were carried out on LBC.

RESULTS

The 37 FNs included 14 atypia of undetermined significance/follicular lesion of undetermined significance and 23 FN. Specifically, atypia of undetermined significance/follicular lesion of undetermined significance resulted in three goitres, 10 follicular adenomas and one NIFTP whereas FN/suspicious for FN by seven follicular adenomas and 16 malignancies (nine non-invasive follicular thyroid neoplasms with papillary-like nuclear features, two invasive follicular variant of papillary thyroid carcinoma [PTC] and five PTC). The 20 positive for malignancy samples included two invasive follicular variant of PTC, 16 PTCs and two medullary carcinomas. The morphological features of BRAF^V600E mutation (nuclear features of PTC and moderate/abundant eosinophilic cytoplasms) were associated with 100% ROM. In the wild type cases, ROM was 83.3% in presence of a concordant positive ICC panel whilst significantly lower (10.5%) in a negative concordant ICC. High expression values of MirR-375 provided 100% ROM.

CONCLUSIONS

The adoption of an algorithm might represent the best choice for the correct diagnosis of FNs. The morphological detection of BRAF^V600E represents the first step for the identification of malignant FNs. A significant reduction of unnecessary thyroidectomies is the goal of this application.

Diagnostic Utility of Molecular and Imaging Biomarkers in Cytological Indeterminate Thyroid Nodules

Indeterminate thyroid cytology (Bethesda III and IV) corresponds to follicular-patterned benign and malignant lesions, which are particularly difficult to differentiate on cytology alone. As ~25% of these nodules harbor malignancy, diagnostic hemithyroidectomy is still custom. However, advanced preoperative diagnostics are rapidly evolving.This review provides an overview of additional molecular and imaging diagnostics for indeterminate thyroid nodules in a preoperative clinical setting, including considerations regarding cost-effectiveness, availability, and feasibility of combining techniques. Addressed diagnostics include gene mutation analysis, microRNA, immunocytochemistry, ultrasonography, elastosonography, computed tomography, sestamibi scintigraphy, [18F]-2-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET), and diffusion-weighted magnetic resonance imaging.The best rule-out tests for malignancy were the Afirma® gene expression classifier and FDG-PET. The most accurate rule-in test was sole BRAF mutation analysis. No diagnostic had both near-perfect sensitivity and specificity, and estimated cost-effectiveness. Molecular techniques are rapidly advancing. However, given the currently available techniques, a multimodality stepwise approach likely offers the most accurate diagnosis, sequentially applying one sensitive rule-out test and one specific rule-in test. Geographical variations in cytology (e.g., Hürthle cell neoplasms) and tumor genetics strongly influence local test performance and clinical utility. Multidisciplinary collaboration and implementation studies can aid the local decision for one or more eligible diagnostics.

miRNA expression and function in thyroid carcinomas: a comparative and critical analysis and a model for other cancers

As in many cancer types, miRNA expression profiles and functions have become an important field of research on non-medullary thyroid carcinomas, the most common endocrine cancers. This could lead to the establishment of new diagnostic tests and new cancer therapies. However, different studies showed important variations in their research strategies and results. In addition, the action of miRNAs is poorly considered as a whole because of the use of underlying dogmatic truncated concepts. These lead to discrepancies and limits rarely considered. Recently, this field has been enlarged by new miRNA functional and expression studies. Moreover, studies using next generation sequencing give a new view of general miRNA differential expression profiles of papillary thyroid carcinoma. We analyzed in detail this literature from both physiological and differential expression points of view. Based on explicit examples, we reviewed the progresses but also the discrepancies and limits trying to provide a critical approach of where this literature may lead. We also provide recommendations for future studies. The conclusions of this systematic analysis could be extended to other cancer types.

Pathological processes and therapeutic advances in radioiodide refractory thyroid cancer

While in most patients with non-medullary thyroid cancer (TC), disease remission is achieved by thyroidectomy and ablation of tumor remnants by radioactive iodide (RAI), a substantial subgroup of patients with metastatic disease present tumor lesions that have acquired RAI resistance as a result of dedifferentiation. Although oncogenic mutations in BRAF, TERT promoter and TP53 are associated with an increased propensity for induction of dedifferentiation, the role of genetic and epigenetic aberrations and their effects on important intracellular signaling pathways is not yet fully elucidated. Also immune, metabolic, stemness and microRNA pathways have emerged as important determinants of TC dedifferentiation and RAI resistance. These signaling pathways have major clinical implications since their targeting could inhibit TC progression and could enable redifferentiation to restore RAI sensitivity. In this review, we discuss the current insights into the pathological processes conferring dedifferentiation and RAI resistance in TC and elaborate on novel advances in diagnostics and therapy to improve the clinical outcome of RAI-refractory TC patients.

MicroRNAs as Biomarkers in Thyroid Carcinoma

Optimal management of patients with thyroid cancer requires the use of sensitive and specific biomarkers. For early diagnosis and effective follow-up, the currently available cytological and serum biomarkers, thyroglobulin and calcitonin, present severe limitations. Research on microRNA expression in thyroid tumors is providing new insights for the development of novel biomarkers that can be used to diagnose thyroid cancer and optimize its management. In this review, we will examine some of the methods commonly used to detect and quantify microRNA in biospecimens from patients with thyroid tumor, as well as the potential applications of these techniques for developing microRNA-based biomarkers for the diagnosis and prognostic evaluation of thyroid cancers.

Molecular Signature of Indeterminate Thyroid Lesions: Current Methods to Improve Fine Needle Aspiration Cytology (FNAC) Diagnosis

Fine needle aspiration cytology (FNAC) represents the gold standard for determining the nature of thyroid nodules. It is a reliable method with good sensitivity and specificity. However, indeterminate lesions remain a diagnostic challenge and researchers have contributed molecular markers to search for in cytological material to refine FNAC diagnosis and avoid unnecessary surgeries. Nowadays, several "home-made" methods as well as commercial tests are available to investigate the molecular signature of an aspirate. Moreover, other markers (i.e., microRNA, and circulating tumor cells) have been proposed to discriminate benign from malignant thyroid lesions. Here, we review the literature and provide data from our laboratory on mutational analysis of FNAC material and circulating microRNA expression obtained in the last 6 years.

The role of miRNAs in the evaluation of follicular thyroid neoplasms: an overview of literature

MicroRNA (miRNA) deregulation has been frequently associated with different human cancers. Not only have miRNAs been involved in almost every cellular function but they have also been linked with a significant number of cancers including thyroid carcinomas. Specifically, thyroid tumors encompass several different miRNA profiles based on the histotypes. Furthermore, thyroid lesions with their broad spectrum of neoplasms (from benign to malignant entities) offer the possibility of studying and recognizing specific subsets of different up-and downregulated miRNAs in each different entity. To date, the majority of authors completed their evaluation mostly by including histologic samples of thyroid tumors. Nonetheless, in the last years, a few studies are focusing on the role of miRNA expression in thyroid fine-needle aspiration cytology (FNAC) regardless of the cytologic preparation, including liquid-based cytology. This growing interest is driven by the possible role of miRNAs in the malignant risk stratification, especially for the indeterminate categories of follicular neoplasms (FNs). In this review we overview the reliability of analyzing miRNAs on thyroid lesions, including those diagnosed as FNs, to identify whether their profiles are likely to distinguish benign from malignant lesions, providing a predictive molecular diagnosis on FNAC.

Cytopathology of Follicular Cell Nodules

The detection of thyroid nodules, consisting of different diseases, represents a common finding in population. Their evaluation and diagnosis are mostly achieved with fine-needle aspiration cytology (FNAC). Even though the majority of thyroid nodules are correctly diagnosed, a total of 25% to 30% of them are classified "indeterminate" comprising lesions with varying risk of malignancy and different types of management. Although the number of thyroid FNACs, including small lesions, is increasing due to the reliance upon sonographic and cytologic interpretations, there are issues concerning cytomorphologic interpretation and interobserver reproducibility. Different classification systems have tried to better define the criteria for inclusion in specific categories and to therefore reduce the rate of indeterminate diagnoses such as atypia of undetermined significance, follicular neoplasms, and suspicious for malignancy. However, the support of ancillary techniques (eg, immunocytochemistry and molecular analysis) are reshaping morphologic diagnoses made on materials obtained from FNAC.

The evaluation of miRNAs on thyroid FNAC: the promising role of miR-375 in follicular neoplasms

Fine needle aspiration cytology (FNAC) plays an essential role in the evaluation of thyroid nodules especially for the category of follicular neoplasms (FN) representing 25 % of all thyroid cases including different neoplastic entities. Hence, one of the most promising areas is the application of molecular tests to FNAC. Among them, microRNAs (miRNA),identified as negative (post-transcriptional) gene expression regulators involved in tumor development, are likely to discriminate among FNs. Limited data explored the use of miRNAs on FNAC as well as their role in the malignant risk stratification. We aimed to define whether liquid-based cytology (LBC) is a valid method for miRNA evaluation. From June 2014 to March 2015, we enrolled 27FNs with histological follow-up. In the same reference period, 13 benign nodules (BN) and 20 positive for malignancy (PM) were selected as controls. Histologically, FNs resulted in 14 malignancies (3 papillary thyroid carcinoma-PTC and 11 follicular variant of PTC-FVPC) and 13 follicular adenomas (FA). The 20 PMs included two FVPC, 16 PTC and two medullary thyroid carcinoma (MTC). Five miRNAs (10b, 92a, 221/222 cluster, and 375) were studied on LBC and quantified by real-time PCR. Only miR-375 was over-expressed in the FNs diagnosed as carcinomas and in the PMs. A cut-off of 12 miR-375/U6 relative ratio recognized all BNs and 95 % PMs. Specifically, in each category, FVPCs and PTCs did not show any difference while MTCs had the highest value. miR-375 shows 97.1 % sensitivity, 100 % specificity, 96.3 % negative predictive value (NPV), 100 % positive predictive value (PPV), and 98.3 % diagnostic accuracy. LBC is suitable for miRNAs evaluation. miR-375 resulted over-expressed in all malignant FNs and 95 % PMs. It may represent a valid aid in ruling out BNs and supporting PTCs and/or FVPCs.

Multicentre validation of a microRNA-based assay for diagnosing indeterminate thyroid nodules utilising fine needle aspirate smears

AIMS

The distinction between benign and malignant thyroid nodules has important therapeutic implications. Our objective was to develop an assay that could classify indeterminate thyroid nodules as benign or suspicious, using routinely prepared fine needle aspirate (FNA) cytology smears.

METHODS

A training set of 375 FNA smears was used to develop the microRNA-based assay, which was validated using a blinded, multicentre, retrospective cohort of 201 smears. Final diagnosis of the validation samples was determined based on corresponding surgical specimens, reviewed by the contributing institute pathologist and two independent pathologists. Validation samples were from adult patients (≥18 years) with nodule size >0.5 cm, and a final diagnosis confirmed by at least one of the two blinded, independent pathologists. The developed assay, RosettaGX Reveal, differentiates benign from malignant thyroid nodules, using quantitative RT-PCR.

RESULTS

Test performance on the 189 samples that passed quality control: negative predictive value: 91% (95% CI 84% to 96%); sensitivity: 85% (CI 74% to 93%); specificity: 72% (CI 63% to 79%). Performance for cases in which all three reviewing pathologists were in agreement regarding the final diagnosis (n=150): negative predictive value: 99% (CI 94% to 100%); sensitivity: 98% (CI 87% to 100%); specificity: 78% (CI 69% to 85%).

CONCLUSIONS

A novel assay utilising microRNA expression in cytology smears was developed. The assay distinguishes benign from malignant thyroid nodules using a single FNA stained smear, and does not require fresh tissue or special collection and shipment conditions. This assay offers a valuable tool for the preoperative classification of thyroid samples with indeterminate cytology.

Thyroid nodule update on diagnosis and management

Thyroid nodules are common. The clinical importance of thyroid nodules is related to excluding malignancy (4.0 to 6.5% of all thyroid nodules), evaluate their functional status and assess for the presence of pressure symptoms. Incidental thyroid nodules are being diagnosed with increasing frequency in the recent years with the use of newer and highly sensitive imaging techniques. The high prevalence of thyroid nodules necessitates that the clinicians use evidence-based approaches for their assessment and management. New molecular tests have been developed to help with evaluation of malignancy in thyroid nodules. This review addresses advances in thyroid nodule evaluation, and their management considering the current guidelines and supporting evidence.

miRNA-106a directly targeting RARB associates with the expression of Na(+)/I(-) symporter in thyroid cancer by regulating MAPK signaling pathway

BACKGROUND

Serum miRNAs profiles between papillary thyroid carcinoma (PTC) patients with non-(131)I and (131)I-avid lung metastases are differentially expressed. These miRNAs have to be further validated and the role of these miRNAs in the molecular function level of thyroid cancer cell lines has not been investigated.

METHODS

Expression levels of six identified miRNAs were assessed via quantitative real-time PCR (qRT-PCR) in the serum of eligible patients. Dual-luciferase reporter assay was used to determine the potential target of miR-106a. Cell viability and apoptosis were evaluated by MTT assay and flow cytometry analysis, respectively. The change of gene expression was detected by qRT-PCR and western blotting analysis. In vitro iodine uptake assay was conducted by a γ-counter.

RESULTS

Compared to PTC patients with (131)I-avid lung metastases, miR-106a was up-regulated in the serum of patients with non-(131)I-avid lung metastases. The results of dual-luciferase reporter assay demonstrated that miR-106a directly targeted retinoic acid receptor beta (RARB) 3'-UTR. miR-106a-RARB promoted viability of thyroid cancer cells by regulating MEKK2-ERK1/2 and MEKK2-ERK5 pathway. miR-106a-RARB inhibited apoptosis of thyroid cancer cells by regulating ASK1-p38 pathway. Moreover, miR-106a-RARB could regulate the expression of sodium iodide symporter, TSH receptor and alter the iodine uptake function of thyroid cancer cells.

CONCLUSIONS

miRNA-106a, directly targeting RARB, associates with the viability, apoptosis, differentiation and the iodine uptake function of thyroid cancer cell lines by regulating MAPK signaling pathway in vitro. These findings in the present study may provide new strategies for the diagnosis and treatment in radioiodine-refractory differentiated thyroid carcinoma.

Value of Molecular Tests in Cytologically Indeterminate Lesions of Thyroid

CONTEXT

Fine-needle aspiration has been the initial step in the workup of thyroid nodular lesions and has successfully reduced the number of unnecessary surgeries and improved preoperative malignancy detection. However, up to one-third of cases fall in the diagnostically "indeterminate group," which poses a patient-management challenge. objective: To review the characteristics of molecular tests useful for stratifying the malignancy risk of indeterminate thyroid lesions, including their advantages and limitations.

DATA SOURCES

PubMed.

CONCLUSIONS

Molecular tests are useful for triage of indeterminate thyroid nodules initially diagnosed by using fine-needle aspiration. Immunocytochemistry is readily available with the shortest turnaround time among the molecular tests but suffers from poor reproducibility and low interpretation concordance. Gene mutation analysis is superior in detecting malignancies as a rule-in test, despite low specificity. Next-generation sequencing seems promising but needs more validations before widespread use. Gene expression profiling is more suitable for detecting benign lesions as a rule-out test to avoid unnecessary surgeries but is not reliable in excluding malignancies. MicroRNA profiling has great potential for both risk stratification and predicting prognosis but is limited by significant variations in sensitivity and specificity. Although many questions still need to be answered, taken together, molecular tests are a promising option for classifying cytologically indeterminate thyroid nodular lesions.

Plasma exosomal miR-21 and miR-181a differentiates follicular from papillary thyroid cancer

Thyroid cancer (TC) is the most common endocrine malignancy and its incidence has increased over the last few decades. As has been revealed by a number of studies, TC tissue's micro-RNA (miRNA) profile may reflect histological features and the clinical behavior of tumor. However, alteration of the miRNA profile of plasma exosomes associated with TC development has to date not been explored. We isolated exosomes from plasma and assayed their characteristics using laser diffraction particle size analysis, atomic force microscopy, and western blotting. Next, we profiled cancer-associated miRNAs in plasma exosomes obtained from papillary TC patients, before and after surgical removal of the tumor. The diagnostic value of selected miRNAs was evaluated in a large cohort of patients displaying different statuses of thyroid nodule disease. MiRNA assessment was performed by RT-qPCR. In total, 60 patients with different types of thyroid nodal pathology were included in the study. Our results revealed that the development of papillary TC is associated with specific changes in exosomal miRNA profiles; this phenomenon can be used for differential diagnostics. MiRNA-31 was found to be over-represented in the plasma exosomes of patients with papillary TC vs. benign tumors, while miRNA-21 helped to distinguish between benign tumors and follicular TC. MiRNA-21 and MiRNA-181a-5p were found to be expressed reciprocally in the exosomes of patients with papillary and follicular TC, and their comparative assessment may help to distinguish between these types of TC with 100 % sensitivity and 77 % specificity.

miRNA profiling, detection of BRAF V600E mutation and RET-PTC1 translocation in patients from Novosibirsk oblast (Russia) with different types of thyroid tumors

BACKGROUND

The postoperative typing of thyroid lesions, which is instrumental in adequate patient treatment, is currently based on histologic examination. However, it depends on pathologist's qualification and can be difficult in some cases. Numerous studies have shown that molecular markers such as microRNAs and somatic mutations may be useful to assist in these cases, but no consensus exists on the set of markers that is optimal for that purpose. The aim of the study was to discriminate between different thyroid neoplasms by RT-PCR, using a limited set of microRNAs selected from literature.

METHODS

By RT-PCR we evaluated the relative levels of 15 microRNAs (miR-221, -222, -146b, -181b, -21, -187, -199b, -144, -192, -200a, -200b, -205, -141, -31, -375) and the presence of BRAF(V600E) mutation and RET-PTC1 translocation in surgically resected lesions from 208 patients from Novosibirsk oblast (Russia) with different types of thyroid neoplasms. Expression of each microRNA was normalized to adjacent non-tumor tissue. Three pieces of lesion tissue from each patient (39 goiters, 41 follicular adenomas, 16 follicular thyroid cancers, 108 papillary thyroid cancers, 4 medullary thyroid cancers) were analyzed independently to take into account method variation.

RESULTS

The diagnostic classifier based on profiling of 13 microRNAs was proposed, with total estimated accuracy varying from 82.7 to 99% for different nodule types. Relative expression of six microRNAs (miR-146b, -21, -221, -222, 375, -199b) appeared significantly different in BRAF(V600E)-positive samples (all classified as papillary thyroid carcinomas) compared to BRAF(V600E)-negative papillary carcinoma samples.

CONCLUSIONS

The results confirm practical feasibility of using molecular markers for typing of thyroid neoplasms and clarification of controversial cases.

MECHANISMS IN ENDOCRINOLOGY: MicroRNA in diagnostics and therapy of thyroid cancer

MicroRNAs, short non-coding regulators of the gene expression, are subjects of numerous investigations assessing their potential use in the diagnostics and management of human diseases. In this review, we focus on studies that analyze the utility of microRNAs as novel diagnostic and therapeutic tools in follicular cell-derived thyroid carcinomas. This very interesting and promising field brings new insight into future strategies for personalized medicine.

Molecular classification of thyroid lesions by combined testing for miRNA gene expression and somatic gene alterations

Multiple molecular markers contribute to the pathogenesis of thyroid cancer and can provide valuable information to improve disease diagnosis and patient management. We performed a comprehensive evaluation of miRNA gene expression in diverse thyroid lesions (n = 534) and developed predictive models for the classification of thyroid nodules, alone or in combination with genotyping. Expression profiling by reverse transcription-quantitative polymerase chain reaction in surgical specimens (n = 257) identified specific miRNAs differentially expressed in 17 histopathological categories. Eight supervised machine learning algorithms were trained to discriminate benign from malignant lesions and evaluated for accuracy and robustness. The selected models showed invariant area under the receiver operating characteristic curve (AUC) in cross-validation (0.89), optimal AUC (0.94) in an independent set of preoperative thyroid nodule aspirates (n = 235), and classified 92% of benign lesions as low risk/negative and 92% of malignant lesions as high risk/positive. Surgical and preoperative specimens were further tested for the presence of 17 validated oncogenic gene alterations in the BRAF, RAS, RET or PAX8 genes. The miRNA-based classifiers complemented and significantly improved the diagnostic performance of the 17-mutation panel (p < 0.001 for McNemar's tests). In a subset of resected tissues (n = 54) and in an independent set of thyroid nodules with indeterminate cytology (n = 42), the optimized ThyraMIR Thyroid miRNA Classifier increased diagnostic sensitivity by 30-39% and correctly classified 100% of benign nodules negative by the 17-mutation panel. In contrast, testing with broad targeted next-generation sequencing panels decreased diagnostic specificity by detecting additional mutations of unknown clinical significance in 19-39% of benign lesions. Our results demonstrate that, independent of mutational status, miRNA expression profiles are strongly associated with altered molecular pathways underlying thyroid tumorigenesis. Combined testing for miRNA gene expression and well-established somatic gene alterations is a novel diagnostic strategy that can improve the preoperative diagnosis and surgical management of patients with indeterminate thyroid nodules.

Pathobiology of MicroRNAs and Their Emerging Role in Thyroid Fine-Needle Aspiration

OBJECTIVE

MicroRNAs (miRs) are noncoding, single-stranded regulatory RNA molecules involved in the posttranscriptional regulation of gene expression. They control the development and maintenance of the diverse cellular processes including proliferation, differentiation, motility and apoptosis. Expression of miRs is tissue-specific and each alteration of the tissue miR profile is associated with a distinct disease status.

STUDY DESIGN

We reviewed the literature on the expression of miRs in thyroid tumors, focusing on methodology and diagnostic and prognostic output. Separately, we analyzed 11 studies on miR profiles in thyroid cytological material.

RESULTS

Numerous studies have evaluated the miR profiles of thyroid tumors in an attempt to find a possible diagnostic and prognostic role. Both downregulation and upregulation of numerous miRs was found, but differences between the surgical pathology specimens and corresponding fine-needle aspirates in the expression of the same miRs were also reported.

CONCLUSIONS

The results from surgically resected material cannot be extrapolated into preoperative use without validation. For diagnostic use, the strong overlap between follicular adenoma and follicular carcinoma miR profiles is challenging. In summary, miR-221 and miR-222 are consistently upregulated in different types of thyroid carcinomas and might be used as markers of malignancy.

2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles on adults were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations for therapeutic interventions. We developed a similarly formatted system to appraise the quality of such studies and resultant recommendations. The guideline panel had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, use of molecular markers, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to screening for thyroid cancer, staging and risk assessment, surgical management, radioiodine remnant ablation and therapy, and thyrotropin suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using imaging and serum thyroglobulin, thyroid hormone therapy, management of recurrent and metastatic disease, consideration for clinical trials and targeted therapy, as well as directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

MicroRNAs as a potential tool in the differential diagnosis of thyroid cancer: a systematic review and meta-analysis

OBJECTIVE

Thyroid cancer is the most common endocrine malignancy, and its incidence has been increasing over the last 30 years. Several studies have suggested that miRNAs may play a significant role in the differential diagnosis of indeterminate thyroid nodules. To systematically evaluate the utility of miRNAs in discriminating malignant thyroid nodules from benign ones on fine-needle aspiration biopsy (FNAB) samples, a systematic review and meta-analysis of the published literatures were carried out.

PATIENTS AND DESIGN

Three hundred and sixty-one samples, obtained from 341 patients, were included in the research, and summary sensitivities (SEN), specificities (SPE), positive likelihood ratios, negative likelihood ratios and diagnostic odds ratio were calculated. Then, summary receiver operating characteristic curves (SROCs) and areas under the SROC curves (AUCs) were calculated to further estimate the overall diagnostic value of miRNAs in thyroid cancer.

RESULTS

The overall pooled SEN, SPE and AUC are 0·75, 0·81 and 0·89, respectively. For multiple miRNAs assays, the pooled SEN, SPE and AUC are 0·87, 0·75 and 0·68, respectively. For single miRNA assays, the corresponding results are 0·71, 0·84 and 0·87, respectively. The corresponding statistical results for differentiating indeterminate FNAB samples are 0·92, 0·68 and 0·86, respectively.

CONCLUSION

Our current meta-analysis suggests that miRNAs may serve as a novel diagnostic tool in distinguishing malignant thyroid nodules from benign ones on FNAB specimens. In addition, subgroup analysis suggests that a panel of miRNAs may have a higher sensitivity but a relatively lower specificity than that of single miRNA in distinguishing thyroid nodules.

The utility of molecular markers in pre-operative assessment of thyroid nodules

The pre-operative diagnosis of thyroid tumors is determined by gold standard fine needle aspiration (FNA) biopsy. This has been widely accepted and offers the most cost-effective approach for evaluation of thyroid nodules. However, its diagnostic accuracy can pose a challenging scenario to surgeons. These diagnostic difficulties may subject patients to unnecessary thyroidectomies for benign thyroid nodules. Thus, additional molecular tests are needed to improve the sensitivity and specificity of FNA. The role of molecular markers is being proposed to predict the type and risk of malignancy to abate the need for diagnostic thyroidectomies. This review discusses their utility and validity in pre-operative diagnosis of thyroid nodules and how these markers can enhance the accuracy of FNA cytology.

Differential expression profiling of circulation microRNAs in PTC patients with non-131I and 131I-avid lungs metastases: a pilot study

INTRODUCTION

Loss of the ability to concentrate (131)I is one of the important causes of radioiodine-refractory disease in papillary thyroid carcinoma (PTC). Recent advantages of serum microRNAs (miRNAs) open a new realm of possibilities for noninvasive diagnosis and prognosis of many cancers. The aim of the current study was to identify differential expression profiling of circulation miRNAs in PTC patients with non-(131)I and (131)I-avid lungs metastases.

METHODS

The expressions of miRNAs were examined using miRNA microarray chip. The most significantly changed miRNAs from microarray were verified by using qRT-PCR. The potential miRNAs regulating target genes and their preliminary biological functions were forecasted by Bioinformatic analysis.

RESULTS

Compared to (131)I-avid lung metastases, 13 kinds of significantly differential serum miRNAs including 5 upregulated miRNAs (miR-1249, miR-106a, miR-503, miR-34c-5p, miR-1281) and 8 downregulated miRNAs (miR-1915, miR-2861, miR-3196, miR-500, miR-572, miR-33b, miR-554, miR-18a) in PTC patients with non-(131) I-avid lung metastases were identified. Bioinformatic analysis demonstrated that miR-106a was the core miRNA regulating 193 genes in the network. The results of validation confirmed the up-regulation of miR-106a in non-(131)I-avid lungs metastatic PTC patients.

CONCLUSION

Differentially expressed serum miRNA profiles between PTC patients with non-(131)I and (131)I-avid lungs metastases were analyzed. These findings in our present study could represent new clues for the diagnostic and therapeutic strategy in PTC patients with non-(131)I-avid metastatic disease.

MicroRNA expression profiles in the management of papillary thyroid cancer

Papillary thyroid cancer (PTC) is the major contributor to the dramatically increasing incidence of thyroid cancer. Low-risk PTC shows the most rapid rate of increase because of changing trends in neck imaging and the use of fine needle aspiration to investigate thyroid nodules. The need for a paradigm shift in the management of these patients, to provide personalized treatment and surveillance plans, has led to the focus on molecular biomarker research. MicroRNAs (miRNAs) compose a class of molecules with promising applications for every stage of PTC management, including diagnosis, prognosis, treatment, and surveillance. Although most of the miRNA studies are currently preclinical, given the rapid progress of scientific discovery, clinical trials will not be far away. Thyroid clinicians will be expected to have good insights into the current status of PTC-related molecular translational research. This article focuses on the potential roles of miRNA in PTC management in the context of contemporary recommended clinical practice.

Deregulation of microRNA expression in thyroid tumors

MicroRNAs (miRNAs or miRs) are endogenous non-coding RNAs that negatively regulate gene expression by binding to the 3' non-coding regions of target mRNAs, resulting in their cleavage or blocking their translation. miRNAs may have an impact on cell differentiation, proliferation, and survival, and their deregulation can be inclined to diseases and cancers, including thyroid tumors. The purpose of this review is to summarize the existing findings of deregulated miRNAs in different types of thyroid tumors and to exhibit their potential target genes, especially to demonstrate those involved in tumor invasion and metastasis. In addition, new findings of circulating miRNA expression profiles, single nucleotide polymorphism (SNP) in thyroid tumors, and the correlation of somatic mutations with deregulated miRNA expression in thyroid tumors were all included in this review.

Deregulation of microRNA expression in thyroid neoplasias

MicroRNAs (miRNAs) have emerged as a class of powerful gene expression regulators. Acting at the post-transcriptional level, miRNAs modulate the expression of at least one-third of the mRNAs that are encoded by the human genome. The expression of a single gene can be regulated by several miRNAs, and every miRNA has more than one target gene. Thus, the miRNA regulatory circuit, which affects essential cellular functions, is of enormous complexity. Moreover, a fundamental role for miRNAs has been determined in the onset and progression of human cancers. Here, we summarize the main alterations in miRNA expression that have been identified in thyroid neoplasias and examine the mechanisms through which miRNA deregulation might promote thyroid cell transformation. We also discuss how the emerging knowledge on miRNA deregulation could be harnessed for the diagnosis and treatment of thyroid neoplasias.