MicroRNA deregulation in human thyroid papillary carcinomas

miRNA-Directed Regulation of the Main Signaling Pathways in Thyroid Cancer

In the last two decades, great strides have been made in the study of microRNAs in development and in diseases such as cancer, as reflected in the exponential increase in the number of reviews on this topic including those on undifferentiated and well-differentiated thyroid cancer. Nevertheless, few reviews have focused on understanding the functional significance of the most up- or down-regulated miRNAs in thyroid cancer for the main signaling pathways hyperactivated in this tumor type. The aim of this review is to discuss the major miRNAs targeting proteins of the MAPK, PI3K, and TGFβ pathways, to define their mechanisms of action through the 3'UTR regions of their target genes, and to describe how they affect thyroid tumorigenesis through their actions on cell proliferation, migration, and invasion. Given the importance of miRNAs in cancer as diagnostic, prognostic and therapeutic candidates, a better understanding of this cross-talk might shed new light on the biomedical treatment of thyroid cancer.

MiR-19a Overexpression in FTC-133 Cell Line Induces a More De-Differentiated and Aggressive Phenotype

In recent years, microRNAs (miRNAs) have received increasing attention for their important role in tumor initiation and progression. MiRNAs are a class of endogenous small non-coding RNAs that negatively regulate the expression of several oncogenes or tumor suppressor genes. MiR-19a, a component of the oncogenic miR-17-92 cluster, has been reported to be highly expressed only in anaplastic thyroid cancer, the most undifferentiated, aggressive and lethal form of thyroid neoplasia. In this work, we evaluated the putative contribution of miR-19a in de-differentiation and aggressiveness of thyroid tumors. To this aim, we induced miR-19a expression in the well-differentiated follicular thyroid cancer cell line and evaluated proliferation, apoptosis and gene expression profile of cancer cells. Our results showed that miR-19a overexpression stimulates cell proliferation and alters the expression profile of genes related to thyroid cell differentiation and aggressiveness. These findings not only suggest that miR-19a has a possible involvement in de-differentiation and malignancy, but also that it could represent an important prognostic indicator and a good therapeutic target for the most aggressive thyroid cancer.

Total circulating cell-free miRNA in plasma as a predictive biomarker of the thyroid diseases

BACKGROUND

Thyroid cancer is a common endocrine cancer. Great progress has been made in resolving its molecular mechanisms in recent years. The molecular changes observed in thyroid cancer can be used as biomarkers for diagnostic, prognostic and therapeutic purposes. MicroRNAs (miRNAs) are important components in biological and metabolic pathways, such as developmental stages, signal transduction, cell maintenance, and differentiation. Hence, their malfunctioning can expose humans to malignancies. miRNA expressions have been shown to be dysregulated in different tumor types, like thyroid cancer, and may cause tumor initiation and progression. In previous studies, only cancer has been studied, and miRNA has been detected from the tissues in all the studies performed. In this study, we have focused on thyroid diseases such as bening nodules and Hashimoto's disease, which might be the cause of thyroid cancer, and have carried out miRNA tests in the blood samples taken from the arms thyroid patients.

MATERIAL AND METHOD

The present study was conducted on the blood samples of 100 thyroid patients. Of the 100 patients in our study, 33 consisted of patients with thyroiditis, while 37 patients were diagnosed with benign thyroid nodules and 30 patients had thyroid cancer. For the control group, 18 patients were included. The plasma samples were analyzed, and the total miRNA levels were determined.

RESULTS

We found that the ccf-miRNA amount of benign patients is significantly lower than that of the controls. Similarly, the miRNA amount in the controls is significantly higher than that of the thyroiditis (P = 0.06) and the malign groups miRNA (P = 0.084). Although the present study has a low number of patients, the plasma samples could be used as a source of circulating miRNAs. In addition, the total miRNA of thyroid diseases could be used as a biomarker for different types of thyroid diseases. We could suggest, for future study, that specific miRNAs in bodily fluid might show specific properties to be used as biomarkers of thyroid diseases.

Altered Epigenetic Mechanisms in Thyroid Cancer Subtypes

Thyroid carcinoma (TC) is the most frequent malignant neoplasm of the endocrine system. Molecular methods for diagnosis of invasive thyroid disease can be effectively adopted. Epigenetic factors play an important role in the diversity patterns of gene expression and the phenotypic and biological characteristics of TC subtypes. We aimed to review epigenetic changes in the main subtypes of TC, along with a presentation of the methods that have examined these changes, and active clinical trials for the treatment of advanced TCs targeting epigenetic changes. A literature analysis was performed in MEDLINE using PubMed, Elsevier, and Google Scholar for studies published up to 2016, using the keywords: "Epigenetic alterations" OR "Epigenetic changes", "thyroid cancers", "papillary thyroid cancer", "medullary thyroid cancer", "follicular thyroid cancer", and "anaplastic thyroid cancer", which resulted in 310 articles in English. All related abstracts were reviewed and studies were included that were published in English, had available full text, and determined the details of the methods and materials associated with the epigenetic patterns of TC and its subtypes (100 articles). Analysis of epigenetic alterations in TC subtypes helps to identify pathogenesis and can play an important role in the classification and diagnosis of tumors. Epigenetic mechanisms, especially aberrant methylation of DNA and microRNAs (miRs), are likely to play an important role in thyroid tumorigenesis. Further studies are required to elucidate the role of histone modification mechanisms in TC development.

Identification of key genes and miRNAs markers of papillary thyroid cancer

OBJECTIVE

In this study, crucial genes and microRNAs (miRNAs) associated with the progression, staging, and prognosis of papillary thyroid cancer (PTC) were identified.

METHODS

Four PTC datasets, including our own mRNA-sequencing (mRNA-seq) dataset and three public datasets downloaded from Gene Expression Omnibus and The Cancer Genome Atlas, were used to analyze differentially expressed genes (DEGs) and miRNAs (DEMs) between PTC tumor tissues and paired normal tissues (control). Gene ontology (GO) terms and pathways associated with these DEGs were identified, and protein-protein interactions (PPIs) were analyzed. Additionally, an miRNA-mRNA regulatory network was constructed and the functions of DEMs were explored. Finally, miRNAs/mRNAs associated with tumor staging and prognosis were identified. The expression levels of several key genes and miRNAs were validated by qRT-PCR.

RESULTS

Numerous DEGs and DEMs were identified between tumor and control groups in four datasets. The DEGs were significantly enriched in cell adhesion and cancer-related GO terms and pathways. In the constructed PPI network, ITGA2, FN1, ICAM1, TIMP1 and CDH2 were hub proteins. In the miRNA-mRNA negative regulatory networks, miR-204-5p regulated the largest number of target genes, such as TNFRSF12A. miR-146b, miR-204, miR-7-2, and FN1 were associated with tumor stage in PTC, and TNFRSF12A and CLDN1 were related to prognosis.

CONCLUSIONS

Our results suggested the important roles of ITGA2, FN1, ICAM1, TIMP1 and CDH2 in the progression of PTC. miR-204-5p, miR-7-2, and miR-146b are potential biomarkers for PTC staging and FN1, CLDN1, and TNFRSF12A may serve as markers of prognosis in PTC.

Exosome: a novel mediator in drug resistance of cancer cells

Exosomes are small membrane vesicles with a diameter of 40–100 nm, which are released into the intracellular environment. Exosomes could influence the genetic and epigenetic changes of receptor cells by promoting the horizontal transfer of various proteins or RNAs, especially miRNAs. Moreover, exosomes also play an important role in tumor microenvironment. Exosomes could promote the short- and long-distance exchanges of genetic information by acting as mediators of cell-to-cell communication. In addition, exosomes participate in drug resistance of tumor cells by genetic exchange between cells. It is reported that exosomes could be absorbed by recipient cells and transmit chemoresistance from drug-resistant tumor cells to sensitive ones. Then understanding the mechanisms of chemotherapy failure and controlling tumor progression effectively will be a major challenge for us. Therefore, in this review, we will briefly reveal the role of exosomes in drug resistance.

Thyroid cancers of follicular origin in a genomic light: in-depth overview of common and unique molecular marker candidates

In recent years, thyroid malignances have become more prevalent, especially among women. The most common sporadic types of thyroid tumors of follicular origin include papillary, follicular and anaplastic thyroid carcinomas. Although modern diagnosis methods enable the identification of tumors of small diameter, tumor subtype differentiation, which is imperative for the correct choice of treatment, is still troublesome. This review discusses the recent advances in the field of molecular marker identification via next-generation sequencing and microarrays. The potential use of these biomarkers to distinguish among the most commonly occurring sporadic thyroid cancers is presented and compared. Geographical heterogeneity might be a differentiator, although not necessarily a limiting factor, in biomarker selection. The available data advocate for a subset of mutations common for the three subtypes as well as mutations that are unique for a particular tumor subtype. Tumor heterogeneity, a known issue occurring within solid malignancies, is also discussed where applicable. Public databases with datasets derived from high-throughput experiments are a valuable source of information that aid biomarker research in general, including the identification of molecular hallmarks of thyroid cancer.

Selumetinib Activity in Thyroid Cancer Cells: Modulation of Sodium Iodide Symporter and Associated miRNAs

BACKGROUND

The MEK (mitogen-activated protein kinase)⁻inhibitor selumetinib led to increased radioiodine uptake and retention in a subgroup of patients suffering from radioiodine refractory differentiated thyroid cancer (RR-DTC). We aimed to analyse the effect of selumetinib on the expression of sodium iodide symporter (NIS; SLC5A5) and associated miRNAs in thyroid cancer cells.

METHODS

Cytotoxicity was assessed by viability assay in TPC1, BCPAP, C643 and 8505C thyroid cancer cell lines. NIS, hsa-let-7f-5p, hsa-miR-146b-5p, and hsa-miR-146b-3p expression was determined by quantitative RT-PCR. NIS protein was detected by Western blot. Radioiodine uptake was performed with a Gamma counter.

RESULTS

Selumetinib caused a significant reduction of cell viability in all thyroid cancer cell lines. NIS transcript was restored by selumetinib in all cell lines. Its protein level was found up-regulated in TPC1 and BCPAP cells and down-regulated in C643 and 8505C cells after treatment with selumetinib. Treatment with selumetinib caused a down-regulation of hsa-let-7f-5p, hsa-miR-146b-5p and hsa-miR-146b-3p in TPC1 and BCPAP cells. In 8505C cells, a stable or down-regulated hsa-miR-146b-5p was detected after 1h and 48h of treatment. C643 cells showed stable or up-regulated hsa-let-7f-5p, hsa-miR-146b-5p and hsa-miR-146b-3p. Selumetinib treatment caused an increase of radioiodine uptake, which was significant in TPC1 cells.

CONCLUSIONS

The study shows for the first time that selumetinib restores NIS by the inhibition of its related targeting miRNAs. Further studies are needed to clarify the exact mechanism activated by hsa-miR-146b-5p, hsa-miR-146b-3p and hsa-let7f-5p to stabilise NIS. Restoration of NIS could represent a milestone for the treatment of advanced RR-DTC.

A Novel Multi-Gene Detection Platform for the Analysis of miRNA Expression

The study of miRNAs and their roles as non-invasive biomarkers has been intensely conducted in cancer diseases over the past decade. Various platforms, ranging from conventional qPCRs to Next Generation Sequencers (NGS), have been widely used to analyze miRNA expression. Here we introduced a novel platform, PanelChip™ Analysis System, which provides a sensitive solution for the analysis of miRNA levels in blood. After conducting miRQC analysis, the system's analytical performance compared favorably against similar nanoscale qPCR-based array technologies. Because PanelChip™ requires only a minimal amount of miRNA for analysis, we used it to screen for potential diagnostic biomarkers in the plasma of patients with oral cavity squamous cell carcinoma (OSCC). Combining the platform with a machine learning algorithm, we were able to discover miRNA expression patterns capable of separating healthy subjects from patients with OSCC.

The epigenetic landscape of differentiated thyroid cancer

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

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.

Individualised Multimodal Treatment Strategies for Anaplastic and Poorly Differentiated Thyroid Cancer

The prognosis of anaplastic (ATC) and poorly differentiated thyroid cancer (PDTC) is poor, due to their radioiodine refractoriness (RAI-R), high metastatic potential and current lack of effective treatment strategies. We aimed to examine the efficacy of the tyrosine kinase inhibitors (TKIs) sorafenib and selumetinib and the histone deacetylase inhibitor (HDACI) panobinostat in patient-derived tumor tissue (PDTT) of ATCs/PDTCs, the expression of sodium iodide symporter (NIS) and radioiodine up-take (RAI-U). High Mobility Group AT-Hook 2 (HMGA2) and associated miRNAs expression was correlated with the clinical course of the patients. Inhibitory effects of panobinostat, sorafenib and selumetinib were measured by real time cell analyser xCELLigence in five PDTTs and human foreskin fibroblasts (HF) used as control. Expression of NIS, HMGA2 and associated miRNAs hsa-let-7f-5p, hsa-let-7b-5p, hsa-miR-146b-5p and hsa-miR-146b-3p was performed by RT-qPCR and Western blot. RAI-U was performed by Gamma Counter with I-131. Panobinostat showed the strongest cytotoxic effect (10 nM) in all PDTTs and HF and caused a significant over-expression of NIS transcript. TKIs were able to up-regulate NIS transcript in patient 5 and in HF. RAI-U was up-regulated after 24 h of treatment with TKIs and panobinostat in all PDTT and HF, except in patient 5. Selumetinib caused a significant suppression of HMGA2 in PDTT 1, 2, 4, 5 and HF; whereas sorafenib caused no change of HMGA2 expression. Panobinostat suppressed significantly HMGA2 in PDTT 2, 4 and HF. The expression of miRNAs hsa-let-7f-5p, has-let-7b-5p hsa-miR-146b-5p and hsa-miR-146b-3p was modulated heterogeneously. NIS protein level was over-expressed in three PDTTs (patients 1, 3 and 4) after 24 h of treatment with selumetinib, sorafenib and in particular with panobinostat. HF showed a stable NIS protein level after treatment. Panobinostat showed the strongest cytotoxicity in all treated PDTTs at the lowest dosage in comparison with TKI. All three compounds were able to modulate differently NIS, HMGA2 and related miRNAs. These factors represent valuable markers in PDTT for new treatment strategies for patients suffering from ATC/PDTC. Thus, the establishment of PDTT could be a useful tool to test the efficacy of compounds and to develop new and individualised multimodal treatment options for PDTCs and ATCs.

Molecular markers in well-differentiated thyroid cancer

PURPOSE

Thyroid nodules are of common occurrence in the general population. About a fourth of these nodules are indeterminate on aspiration cytology placing many a patient at risk of unwanted surgery. The purpose of this review is to discuss various molecular markers described to date and place their role in proper perspective. This review covers the fundamental role of the signaling pathways and genetic changes involved in thyroid carcinogenesis. The current literature on the prognostic significance of these markers is also described.

METHODS

PubMed was used to search relevant articles. The key terms "thyroid nodules", "thyroid cancer papillary", "carcinoma papillary follicular", "carcinoma papillary", "adenocarcinoma follicular" were searched in MeSH, and "molecular markers", "molecular testing", mutation, BRAF, RAS, RET/PTC, PAX 8, miRNA, NIFTP in title and abstract fields. Multiple combinations were done and a group of experts in the subject from the International Head and Neck Scientific Group extracted the relevant articles and formulated the review.

RESULTS

There has been considerable progress in the understanding of thyroid carcinogenesis and the emergence of numerous molecular markers in the recent years with potential to be used in the diagnostic algorithm of these nodules. However, their precise role in routine clinical practice continues to be a contentious issue. Majority of the studies in this context are retrospective and impact of these mutations is not independent of other prognostic factors making the interpretation difficult.

CONCLUSION

The prevalence of these mutations in thyroid nodule is high and it is a continuously evolving field. Clinicians should stay informed as recommendation on the use of these markers is expected to evolve.

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.

Circulating microRNA124-3p, microRNA9-3p and microRNA196b-5p may be potential signatures for differential diagnosis of thyroid nodules

It is important to develop an effective auxiliary approach to distinguish papillary thyroid carcinoma (PTC) from benign nodules because a considerable proportion cannot be identified by fine-needle aspiration cytology at present, resulting in unnecessary thyroidectomy. Circulating miRNAs are potential biomarkers for differential diagnosis of tumors. We aimed to investigate the dysregulation of circulating miRNAs in PTC and evaluate the diagnostic value for differentiation of PTC from benign nodules. We first assessed the expression of miRNAs in patients with PTC, patients with benign nodules and healthy controls using a miRCURY LNA Array (n = 3 for each group). Expression of circulating miR-124-3p, miR-9-3p and miR-5691 was significantly up-regulated, while miR-4701 and miR-196b-5p were down-regulated in PTC patients. The dysregulation of miR-124-3p, miR-9-3p, miR-4701 and miR-196b-5p was further validated by qRT-PCR in fifty participants from each group. The expression of circulating miR-124-3p and miR-9-3p was significantly up-regulated in PTC patients. Both miR-124-3p and miR-9-3p could distinguish PTC from benign nodules with high sensitivity and specificity. There were no significant differences in the expression of circulating miR-4701 and miR-196b-5p between PTC patients and healthy controls. Nevertheless, patients with benign nodules showed a higher level of miR-196b-5p compared with that of PTC patients and healthy controls. ROC analysis indicated that miR-196b-5p had a good diagnostic value for differentiation of benign nodules from PTC. Our study suggested that miR-124-3p, miR-9-3p and miR-196b-5p may be potential signatures for differential diagnosis of thyroid nodules in eastern coastal areas of China.

The role of microRNAs in different types of thyroid carcinoma: a comprehensive analysis to find new miRNA supplementary therapies

The most common endocrine malignancy is thyroid cancer, and researchers have made a great deal of progress in deciphering its molecular mechanisms in the recent years. Many of molecular changes observed in thyroid cancer can be used as biomarkers for diagnosis, prognosis, and therapeutic targets for treatment. MicroRNAs (miRNAs) are important parts in biological and metabolic pathways such as regulation of developmental stages, signal transduction, cell maintenance, and differentiation. Therefore, their dysregulation can expose individuals to malignancies. It has been proved that miRNA expression is dysregulated in different types of tumors, like thyroid cancers, and can be the cause of tumor initiation and progression. In this paper, we have reviewed the available data on miRNA dysregulation in different thyroid tumors including papillary, follicular, anaplastic, and medullary thyroid carcinomas aiming to introduce the last updates in miRNAs-thyroid cancer relation.

Down-regulation of 14q32-encoded miRNAs and tumor suppressor role for miR-654-3p in papillary thyroid cancer

Papillary thyroid carcinoma (PTC) is the most prevalent malignant neoplasia of the thyroid gland. A fraction of PTC cases show loss of differentiation and aggressive behavior, with radioiodine therapy resistance and metastasis. Although microRNAs (miRNAs) emerged as promising molecular markers for PTC, their role in the loss of differentiation observed during PTC progression remains to be fully understood. We performed the large-scale analysis of miRNA expression during PTC progression in BRAFT1799A-transgenic animals (Tg-Braf) and thyroid cancer cell lines and identified the marked downregulation of several miRNAs from the region 14q32. Data from The Cancer Genome Atlas (TCGA) confirmed the global downregulation of miRNAs from the 14q32 region in human PTC. The regulatory network potentially suppressed by these miRNAs suggests that key cancer-related biological processes such as cell proliferation, adhesion, migration and angiogenesis. Among the downregulated miRNAs, we observed that miR-654-3p levels decrease with long-term PTC progression in Tg-Braf mice and inversely correlate with EMT. The in vitro restoration of miR-654-3p decreased cell proliferation and migration and induced reprogramming of metastasis-related genes, suggesting a tumor suppressor role for this miRNA. In conclusion, we show global downregulation of 14q32-encoded miRNAs in an in vivo model of PTC progression. The potential circuitry in which these miRNAs are involved suggests that these miRNAs could play a key role in the pathophysiology of PTC and therefore be relevant for the development of new therapeutic strategies.

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.

Friend or Foe: MicroRNAs in the p53 network

The critical tumor suppressor gene TP53 is either lost or mutated in more than half of human cancers. As an important transcriptional regulator, p53 modulates the expression of many microRNAs. While wild-type p53 uses microRNAs to suppress cancer development, microRNAs that are activated by gain-of-function mutant p53 confer oncogenic properties. On the other hand, the expression of p53 is tightly controlled by a fine-tune machinery including microRNAs. MicroRNAs can target the TP53 gene directly or other factors in the p53 network so that expression and function of either the wild-type or the mutant forms of p53 is downregulated. Therefore, depending on the wild-type or mutant p53 context, microRNAs contribute substantially to suppress or exacerbate tumor development.

Can current molecular tests help in the diagnosis of indeterminate thyroid nodule FNAB?

Approximately 15-30% of all thyroid nodules evaluated with fine-needle aspiration biopsy (FNAB) are classified as cytologically indeterminate. The stepwise unraveling of the molecular etiology of thyroid nodules has provided the basis for a better understanding of indeterminate samples and an opportunity to decrease diagnostic surgery in this group of patients. Over the last 15 years, several studies have tested different methodologies to detect somatic mutations (by polymerase chain reaction and next-generation sequencing, for example), and to identify differentially expressed genes or microRNA, aiming at developing molecular tests to improve the presurgical diagnosis of cytologically indeterminate nodules. In this review, we will provide an overview of the currently available molecular tests and the impact of mutation testing on the diagnosis of thyroid cancer. We will also review current published data and future perspectives in molecular testing of thyroid nodule FNAB and describe the current Brazilian experience with this diagnostic approach. Based on currently available data, especially for countries outside the US-Europe axis, a rational use of these tests must be made to avoid errors with regard to test indication and interpretation of test outcomes. In addition to clinical, radiological, and cytological features, we still need to determine local malignancy rates and conduct more independent validation and comparative performance studies of these tests before including them into our routine approach to indeterminate FNAB.

LncRNA Gas5 acts as a ceRNA to regulate PTEN expression by sponging miR-222-3p in papillary thyroid carcinoma

Accumulating evidence demonstrates that the long non-coding RNA Growth Arrest-Specific 5 (Gas5) has practical significance in cancer progression and metastasis. However, its role and function in papillary thyroid carcinoma (PTC) remains unknown. In this study, we aimed to explore the potential involvement of Gas5 in papillary thyroid carcinogenesis and to highlight the emerging roles of ceRNAs in the biological regulation of PTC cells. The results suggested that Gas5 was markedly downregulated in both PTC tissues and PTC cell lines. Over-expression of Gas5 remarkably suppressed PTC cells proliferation in vitro and inhibited the growth of tumor cells in vivo likewise. Furthermore, Gas5 was identified as a target of miR-222-3p which was aberrantly high in PTC cells. Enhanced expression of miR-222-3p promoted the proliferation of PTC cells while knocking down miR-222-3p could inhibit it. The advanced effects of miR-222-3p on the proliferation of PTC cells could be partly reversed by the upregulation of Gas5 expression. Furthermore, we validated that Gas5 increased the protein level of the PTEN, one of miR-222-3p’s targets, which further activated PTEN/AKT pathway. Taken together, our study identified a tumor suppressive role of Gas5 in PTC cells acting as a ceRNA, effectively becoming a sink for miR-222-3p, modulating the expression of PTEN, which lead to PTEN/AKT pathway activation and proliferation suppression. This finding may offer a new potential therapeutic strategy for PTC.

Identification of novel diagnostic biomarkers for thyroid carcinoma

Thyroid carcinoma (THCA) is the most universal endocrine malignancy worldwide. Unfortunately, a limited number of large-scale analyses have been performed to identify biomarkers for THCA. Here, we conducted a meta-analysis using 505 THCA patients and 59 normal controls from The Cancer Genome Atlas. After identifying differentially expressed long non-coding RNA (lncRNA) and protein coding genes (PCG), we found vast difference in various lncRNA-PCG co-expressed pairs in THCA. A dysregulation network with scale-free topology was constructed. Four molecules (LA16c-380H5.2, RP11-203J24.8, MLF1 and SDC4) could potentially serve as diagnostic biomarkers of THCA with high sensitivity and specificity. We further represent a diagnostic panel with expression cutoff values. Our results demonstrate the potential application of those four molecules as novel independent biomarkers for THCA diagnosis.

miR-451a is underexpressed and targets AKT/mTOR pathway in papillary thyroid carcinoma

Papillary Thyroid Carcinoma (PTC) is the most frequent thyroid cancer. Although several PTC-specific miRNA profiles have been reported, only few upregulated miRNAs are broadly recognized, while less consistent data are available about downregulated miRNAs. In this study we investigated miRNA deregulation in PTC by miRNA microarray, analysis of a public dataset from The Cancer Genome Atlas (TCGA), literature review and meta-analysis based on a univocal miRNA identifier derived from miRBase v21. A list of 18 miRNAs differentially expressed between PTC and normal thyroid was identified and validated in the TCGA dataset. Furthermore, we compared our signature with miRNA profiles derived from 15 studies selected from literature. Then, to select possibly functionally relevant miRNA, we integrated our miRNA signature with those from two in vitro cell models based on the PTC-driving oncogene RET/PTC1. Through this strategy, we identified commonly deregulated miRNAs, including miR-451a, which emerged also by our meta-analysis as the most frequently reported downregulated miRNA. We showed that lower expression of miR-451a correlates with aggressive clinical-pathological features of PTC as tall cell variant, advanced stage and extrathyroid extension. In addition, we demonstrated that ectopic expression of miR-451a impairs proliferation and migration of two PTC-derived cell lines, reduces the protein levels of its recognized targets MIF, c-MYC and AKT1 and attenuates AKT/mTOR pathway activation.

Overall, our study provide both an updated overview of miRNA deregulation in PTC and the first functional evidence that miR-451a exerts tumor suppressor functions in this neoplasia.

MicroRNA-144 inhibits proliferation by targeting WW domain-containing transcription regulator protein 1 in papillary thyroid cancer

Papillary thyroid carcinoma (PTC), the most common histological subtype of thyroid cancer, accounts for between 80 and 90% of all thyroid cancer cases. Previous studies have suggested that microRNAs (miRNAs/miRs) are involved in the development of PTC. The aim of the present study was to investigate whether miR-144 inhibits cellular proliferation in PTC. The expression of miR-144 was detected in PTC and corresponding adjacent non-cancerous tissues, and in the PTC cell line IHH4, using reverse transcription-quantitative polymerase chain reaction. Associations between miR-144 expression levels and the clinicopathological characteristics were analyzed. Receiver operating characteristic (ROC) curves were used to assess the diagnostic value of miR-144 expression, and the potential function of miR-144 was investigated in IHH4 cells using a Cell Counting Kit-8 and colony formation assays. Western blotting was applied to analyze the expression level of WW domain-containing transcription regulator 1 (WWTR1) in PTC tissues. miR-144 was significantly downregulated in PTC tissues and the PTC cell line. Low expression of miR-144 was associated with larger tumor sizes (P<0.001). The ROC curves demonstrated that miR-144 may be a potential biomarker for identifying PTC and non-cancerous diseases (sensitivity, 58.7%; specificity, 87.3%) as well as to differentiate PTC with tumor sizes ≥2 cm (sensitivity, 79.2%; specificity, 69.2%). Upregulation of miR-144 significantly suppressed proliferation in IHH4 cells. WWTR1 was overexpressed in PTC tissues compared with in adjacent non-cancerous tissues, and the ectopic expression of miR-144 downregulated WWTR1 in IHH4 cells. Co-transfection with pcDNA-WWTR1 and miR-144 ‘rescued’ the proliferation inhibition. The results of the present study collectively demonstrated that miR-144 is downregulated in PTC, that low expression levels of miR-144 are associated with larger tumor sizes and that miR-144 inhibits cellular proliferation in PTC by targeting WWTR1.

MicroRNAs in thyroid development, function and tumorigenesis

MicroRNAs (miRNAs) are important post-transcriptional regulators of gene expression that modulate the vast majority of cellular processes. During development, the correct timing and expression of miRNAs in the tissue differentiation is essential for organogenesis and functionality. In thyroid gland, DICER and miRNAs are necessary for accurately establishing thyroid follicles and hormone synthesis. Moreover, DICER1 mutations and miRNA deregulation observed in human goiter influence thyroid tumorigenesis. The thyroid malignant transformation by MAPK oncogenes is accompanied by global miRNA changes, with a marked reduction of "tumor-suppressor" miRNAs and activation of oncogenic miRNAs. Loss of thyroid cell differentiation/function, and consequently iodine trapping impairment, is an important clinical characteristic of radioiodine-refractory thyroid cancer. However, few studies have addressed the direct role of miRNAs in thyroid gland physiology. Here, we focus on what we have learned in the thyroid follicular cell differentiation and function as revealed by cell and animal models and miRNA modulation in thyroid tumorigenesis.

Role of microRNAs in endocrine cancer metastasis

The deregulation of transcription and processing of microRNAs (miRNAs), as well as their function, has been involved in the pathogenesis of several human diseases, including cancer. Despite advances in therapeutic approaches, cancer still represents one of the major health problems worldwide. Cancer metastasis is an aggravating factor in tumor progression, related to increased treatment complexity and a worse prognosis. After more than one decade of extensive studies of miRNAs, the fundamental role of these molecules in cancer progression and metastasis is beginning to be elucidated. Recent evidences have demonstrated a significant role of miRNAs on the metastatic cascade, acting either as pro-metastatic or anti-metastatic. They are involved in distinct steps of metastasis including epithelial-to-mesenchymal transition, migration/invasion, anoikis survival, and distant organ colonization. Studies on the roles of miRNAs in cancer have focused mainly on two fronts: the establishment of a miRNA signature for different tumors, which may aid in early diagnosis using these miRNAs as markers, and functional studies of specific miRNAs, determining their targets, function and regulation. Functional miRNA studies on endocrine cancers are still scarce and represent an important area of research, since some tumors, although not frequent, present a high mortality rate. Among the endocrine tumors, thyroid cancer is the most common and best studied. Several miRNAs show lowered expression in endocrine cancers (i.e. miR-200s, miR-126, miR-7, miR-29a, miR-30a, miR-137, miR-206, miR-101, miR-613, miR-539, miR-205, miR-9, miR-195), while others are commonly overexpressed (i.e. miR-21, miR-183, miR-31, miR-let7b, miR-584, miR-146b, miR-221, miR-222, miR-25, miR-595). Additionally, some miRNAs were found in serum exosomes (miR-151, miR-145, miR-31), potentially serving as diagnostic tools. In this review, we summarize studies concerning the discovery and functions of miRNAs and their regulatory roles in endocrine cancer metastasis, which may contribute for the finding of novel therapeutic targets. The review focus on miRNAs with at least some identified targets, with established functions and, if possible, upstream regulation.

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.

Functional analysis of a novel, thyroglobulin-embedded microRNA gene deregulated in papillary thyroid carcinoma

MicroRNAs, non-coding regulators of gene expression, are known culprits of thyroid cancer. Using next-generation sequencing, we identified a novel microRNA gene, encoded within an important thyroid regulator - thyroglobulin, and analyzed its functionality in the thyroid gland. In vitro and in silico analyses proved that the novel miR-TG is processed from the precursor, and co-expressed with thyroglobulin. Both genes are specific for thyroid tissue and downregulated in papillary thyroid carcinoma by 44% (p = 0.04) and 48% (p = 0.001), respectively. Putative target genes for miR-TG were identified using in silico tools, which pinpointed MAP4K4, an oncogene upregulated in thyroid cancer. Analysis of transcriptome by RNA-seq revealed that overexpression of miR-TG in PTC-derived cell line led to downregulation of several genes, including MAP4K4 (fold change 0,82; p = 0.036). The finding was confirmed by SQ-PCR (fold change 071; p = 0.004). Direct interaction between miR-TG and MAP4K4 was confirmed in the luciferase assay (p = 0.0006). Functional studies showed increase proliferation in K1 cell line transfected with miR-TG. We propose that in normal thyroid miR-TG plays a fine-tuning effect on the maintenance of MAPK pathway, inhibiting the expression of miR's target MAP4K4. This regulation is disturbed in cancer due to downregulation of the novel, thyroglobulin-embedded microRNA, characterized in this study.

Wound fluids affect miR-21, miR-155 and miR-221 expression in breast cancer cell lines, and this effect is partially abrogated by intraoperative radiation therapy treatment

Breast cancer is the most common malignant disease occurring in women. Conservative breast cancer surgery followed by radiation therapy is currently the standard treatment for this type of cancer. The majority of metastases occur within the scar, which initiated a series of studies. As a result, clinical trials aimed to assess whether localized radiotherapy, as intraoperative radiotherapy (IORT), may more effective in inhibiting the formation of local recurrence compared with the standard postoperative whole breast radiotherapy. The present study determined the role of postoperative wound fluids (WFs) from patients diagnosed with breast cancer subsequent to breast conserving surgery or breast conserving surgery followed by IORT on the expression of three microRNAs (miRNAs), consisting of miR-21, miR-155 and miR-221, in distinct breast cancer cell lines that represent the general subtypes of breast cancer. It was determined that the miRNAs responsible for breast cancer progression, induction of tumorigenesis and enrichment of the cancer stem cell phenotype, which is responsible for resistance to tumor therapy, were highly upregulated in the human epidermal growth factor receptor 2-positive breast cancer SK-BR-3 cell line following stimulation with WFs. It is worth emphasizing, that those changes were more significant in WFs collected from patients after surgery alone. The BT-549 cell line showed altered expression only of miR-155 following incubation with WFs. Notably, this change was not associated with IORT. Additionally, it was indicated that both WFs and RT-WF strongly downregulated the expression of miR-21, miR-155 and miR-221 in basal/epithelial and luminal subtypes of breast cancer. It was concluded that the present study contributes to an increased understanding of the role of surgical WFs and IORT treatment in the regulation of miRNA expression. This may enable the development of the current knowledge of breast cancer biology subsequent to IORT treatment and substantially to improve the therapy in the future.

Circulating thyroid cancer biomarkers: Current limitations and future prospects

Differentiated thyroid cancer (DTC) is the most common malignancy of the endocrine system. There has been a significant increase in its incidence over the past two decades attributable mainly to the use of more sensitive diagnostic modalities. Ultrasound-guided fine needle aspiration cytology is the mainstay of diagnosis of benign disorders and malignancy. However, approximately 20% of lesions cannot be adequately categorized as benign or malignant. In the postoperative setting, monitoring of thyroglobulin (Tg) levels has been employed for the detection of disease recurrence. Unfortunately, Tg antibodies are common and interfere with Tg measurement in this subset of patients. Despite this limitation, Tg remains the sole widely used thyroid cancer biomarker in the clinical setting. In an attempt to bypass antibody interference, research has focused mainly on mRNA targets thought to be exclusively expressed in thyroid cells. Tg and thyroid stimulating hormone receptor (TSHR) mRNA have been extensively studied both for discerning between benign disease and malignancy and in postoperative disease surveillance. However, results among reports have been inconsistent probably reflecting considerable differences in methodology. Recently, microRNA (miRNA) targets are being investigated as potential biomarkers in DTC. MiRNAs are more stable molecules and theoretically are not as vulnerable as mRNA during manipulation. Initial results have been encouraging but large-scale studies are warranted to verify and elucidate their potential application in diagnosis and postoperative surveillance of thyroid cancer. Several other novel targets, primarily mutations and circulating cells, are currently emerging as promising thyroid cancer circulating biomarkers. Although interesting and intriguing, data are limited and derive from small-scale studies in specific patient cohorts. Further research findings demonstrating their value are awaited with anticipation.

Downregulation of miR-222 Induces Apoptosis and Cellular Migration in Adenoid Cystic Carcinoma Cells

Previous studies have shown that miR-222 targets the p53 upregulated modulator of apoptosis (PUMA) to regulate cell biological behavior in some human malignancies. We hypothesized that there was a negative regulation, which might induce apoptosis, between miR-222 and PUMA in adenoid cystic carcinoma (ACC). In this study, the expression levels of miR-222 and the PUMA gene after transfection with antisense miR-222 (As-miR-222) were evaluated by RT-PCR and Western blot assays. Cell proliferation and migratory abilities were detected by CCK-8 and Transwell assays. Cell cycle and apoptosis were analyzed by flow cytometry. Our results showed that, when compared with the control and scramble-transfected groups, the expression of miR-222 in the As-miR-222 group was downregulated, while the expression of PUMA at both mRNA and protein levels was upregulated, cell proliferation and migratory abilities were inhibited, and apoptosis was increased. Our results suggested that As-miR-222 transfection could upregulate the expression of PUMA to induce apoptosis in ACC, providing a new concept for the treatment of ACC.

MicroRNA-146b: A Novel Biomarker and Therapeutic Target for Human Papillary Thyroid Cancer

Papillary thyroid cancer (PTC) is the most common tumor subtype of thyroid cancer. However, not all PTCs are responsive to current surgical and radioiodine treatment. The well-established clinical prognostic factors include tumor size, lymph node/distal metastasis, and extrathyroidal invasion. The RET/PTC-RAS-BRAF linear molecular signaling cascade is known to mediate PTC pathogenesis. However, whether presence of BRAF mutation, the most common genetic alteration in PTC, can affect PTC behavior and prognosis is controversial. MicroRNAs (miRNAs) have been labeled as promising molecular prognostic markers in several tumor types. Our recent studies demonstrated that microRNA-146b (miR-146b) deregulation is associated with PTC aggressiveness and prognosis. Here we summarize the current knowledge related to the functional roles, regulated target genes, and clinical applications of miR-146b in PTC and discuss how these studies provide insights into the key role of miR-146b as an oncogenic regulator promoting cellular transformation as well as a prognosis marker for tumor recurrence in PTC. In conjunction with the current perspectives on miRNAs in a wide variety of human cancers, this review will hopefully translate these updated findings on miR-146b into more comprehensive diagnostic or prognostic information regarding treatment in PTC patients before surgical intervention and follow up strategies.

Microarray profiling of circular RNAs in human papillary thyroid carcinoma

BACKGROUND

Non-coding circular RNAs (circRNAs) have displayed dysregulated expression in several human cancers. Here, we profiled the circRNA expression of papillary thyroid carcinoma (PTC) tumors to improve our understanding of PTC pathogenesis.

METHODS

Microarray profiling was performed on 18 thyroid samples, consisting of six PTC tumors, six matching contralateral normal samples, and six benign thyroid lesions. After low-intensity filtering, hierarchical clustering revealed the circRNA expression patterns. Statistical analysis followed by qRT-PCR validation identified the differential circRNAs. MicroRNA (miRNA) target prediction software identified putative miRNA response elements (MREs), which were used to construct a network map of circRNA-miRNA interactions for the differential circRNAs. Bioinformatics platforms predicted cancer-related circRNA-miRNA associations and putative downstream target genes, respectively.

RESULTS

A total of 88 circRNAs and 10 circRNAs were significantly upregulated and downregulated, respectively, in PTC tumors relative to normal thyroid tissue, while 129 circRNAs and 226 circRNAs were significantly upregulated and downregulated, respectively, in PTC tumors relative to benign thyroid lesions. A total of 12 upregulated and four downregulated circRNAs were overlapping between the foregoing comparisons. One downregulated circRNA (hsa_circRNA_100395) showed interactive potential with two cancer-related miRNAs (miR-141-3p and miR-200a-3p). From this analysis, we identified several promising cancer-related genes that may be targets of the dysregulated hsa_circRNA_100395/miR-141-3p/miR-200a-3p axis in PTC tumors.

CONCLUSIONS

circRNA dysregulation may play a role in PTC pathogenesis, and several key circRNAs show promise as candidate biomarkers for PTC. The hsa_circRNA_100395/miR-141-3p/ miR-200a-3p axis may be involved in the pathogenesis of PTC.

In Hepatocellular Carcinoma miR-221 Modulates Sorafenib Resistance through Inhibition of Caspase-3-Mediated Apoptosis

Purpose: The aberrant expression of miR-221 is a hallmark of human cancers, including hepatocellular carcinoma (HCC), and its involvement in drug resistance, together with a proved in vivo efficacy of anti-miR-221 molecules, strengthen its role as an attractive target candidate in the oncologic field. The discovery of biomarkers predicting the response to treatments represents a clinical challenge in the personalized treatment era. This study aimed to investigate the possible role of miR-221 as a circulating biomarker in HCC patients undergoing sorafenib treatment as well as to evaluate its contribution to sorafenib resistance in advanced HCC.Experimental Design: A chemically induced HCC rat model and a xenograft mouse model, together with HCC-derived cell lines were employed to analyze miR-221 modulation by Sorafenib treatment. Data from the functional analysis were validated in tissue samples from surgically resected HCCs. The variation of circulating miR-221 levels in relation to Sorafenib treatment were assayed in the animal models and in two independent cohorts of patients with advanced HCC.Results: MiR-221 over-expression was associated with Sorafenib resistance in two HCC animal models and caspase-3 was identified as its target gene, driving miR-221 anti-apoptotic activity following Sorafenib administration. Lower pre-treatment miR-221 serum levels were found in patients subsequently experiencing response to Sorafenib and an increase of circulating miR-221 at the two months assessment was observed in responder patients.Conclusions: MiR-221 might represent a candidate biomarker of likelihood of response to Sorafenib in HCC patients to be tested in future studies. Caspase-3 modulation by miR-221 participates to Sorafenib resistance. Clin Cancer Res; 23(14); 3953-65. ©2017 AACR.

MiR-221, a potential prognostic biomarker for recurrence in papillary thyroid cancer

Background

Many studies have reported several transcriptionally deregulated microRNAs (miRNAs) in papillary thyroid cancer (PTC) tissue in comparison with benign thyroid nodules and normal thyroid tissues. However, the correlation between miRNA expressions and PTC recurrence still remains unclear.

Methods

The PTC patients who scheduled to undergo total thyroidectomy by the same surgical team in Ningbo NO.2 Hospital from March 1998 to March 2008 were enrolled in this study. The clinical and pathological characteristics of each patient were recorded in detail. The selected miRNA expressions were detected using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Potential predictive factors for cancer recurrence were evaluated by univariate and multivariate Cox proportional hazard analysis.

Results

A total of 78 patients were enrolled with 49 females at a mean age of 45.8 years. Enrolled patients were divided into two groups: nonrecurrent group (n = 54) and recurrent group (n = 24). The results from the univariate Cox proportional hazard analysis revealed that primary tumor size, TNM stage, extrathyroid extension, miR-221, and miR-222 expressions were significantly associated with PTC recurrence (P < 0.05). The tissue expression of miR-221 was the only independent risk factor for PTC recurrence (HR 1.41; 95%CI 1.14–1.95, P = 0.007) by multiple Cox proportional hazard analysis.

Conclusions

This study identified the potential role of miR-221 as a prognostic biomarker for the recurrence in PTC.

MicroRNAs: Biomarkers, Diagnostics, and Therapeutics

MicroRNAs (miRNAs) are small noncoding RNAs (21-23 nucleotides in length) that regulate gene expression at translational or posttranslational levels. The major regulatory mechanisms include translational repression or mRNA degradation (Filipowicz et al., Curr Opin Struct Biol 15:331-341, 2005).Aberrant expression of miRNAs has been found to be associated with a variety of human diseases such as cancers/tumors, diabetes, viral infections, cardiovascular diseases, neurodegenerative diseases, and other diseases (Wang et al., J Cell Physiol 23:25-30, 2016; Lawrie, MicroRNAs in medicine, 2013). The expression of miRNAs is tissue specific and can be used to identify tumor type and its origin (Mishra and Merlino, J Clin Invest 119:2119-2123, 2009). Many investigations suggest that the miRNA-expression profiles are novel diagnostic and prognostic biomarkers for multiple human diseases. Manipulating relevant miRNA expression or function may serve as potential therapeutic strategies for different diseases.

Expression of MicroRNAs in Thyroid Carcinoma

MicroRNA (miRNA) are negative regulators of gene expression and subsequent protein production. This method of action translates into regulatory control over cellular processes, including development, signaling, metabolism, and apoptosis. A broad range of miRNA are shown to have abnormal expressions in thyroid cancers which could explain the pathology of tumor oncogenesis and disease progression. A review is conducted of the current research on miRNA dysregulation in thyroid cancers, including papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), anaplastic thyroid cancer (ATC), and medullary thyroid carcinoma (MTC). Dysregulated miRNA and their associated regulatory pathways are identified and their oncogenic and pathological significance are discussed.

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.

miRNA expression profiling of 'noninvasive follicular thyroid neoplasms with papillary-like nuclear features' compared with adenomas and infiltrative follicular variants of papillary thyroid carcinomas

Follicular variants of papillary thyroid carcinoma include encapsulated (with or without capsular/vascular invasion) and infiltrative forms, which have different clinical behaviors. The encapsulated forms that lack capsular invasion have an indolent clinical behavior that is similar to benign lesions; therefore, they were recently reclassified as 'noninvasive follicular thyroid neoplasms with papillary-like nuclear features' (NIFTPs). Because NIFTPs have nuclear features of papillary carcinomas, distinguishing between NIFTPs and infiltrative follicular variant of papillary thyroid carcinoma is almost impossible with cytological examination. The aim of this study is to determine whether miRNA expression profiles may help distinguish between NIFTPs versus follicular adenomas and infiltrative follicular variant of papillary thyroid carcinomas. The expression profiling of 798 miRNAs was tested in 54 thyroid tumors, including 18 follicular adenomas, 19 NIFTPs and 17 infiltrative follicular variant of papillary thyroid carcinomas, using nCounter Nanostring. We found that miR-146-5p, miR-221-5p, miR-222-3p, miR-30e-3p, and miR-152-3p could discriminate between benign and malignant lesions with a very high level of significance (P-value<0.001). High expression levels of miR-146-5p, miR-199a-5p, miR-199b-5p, miR-1285-5p, miR-1915-3p, and miR-4516, and low miR-148b-3p expression were associated with infiltrative growth of follicular variant of papillary thyroid carcinomas. Interestingly, miR-152-3p, miR-185-5p, and miR-574-3p were significantly downregulated in NIFTPs compared with follicular adenomas, whereas miR-10a-5p and miR-320e can discriminate between NIFTPs and infiltrative forms of follicular variant of papillary thyroid carcinomas. In conclusion, a panel of these markers could have high diagnostic potential as well as could be applied to presurgical fine-needle aspiration, especially for lesions classified as indeterminate thyroid nodules.

TP53/MicroRNA Interplay in Hepatocellular Carcinoma

The role of microRNAs as oncogenes and tumor suppressor genes has emerged in several cancers, including hepatocellular carcinoma (HCC). The pivotal tumor suppressive role of p53-axis is indicated by the presence of inactivating mutations in TP53 gene in nearly all cancers. A close interaction between these two players, as well as the establishment of complex p53/miRNAs loops demonstrated the strong contribution of p53-effector miRNAs in enhancing the p53-mediated tumor suppression program. On the other hand, the direct and indirect targeting of p53, as well as the regulation of its stability and activity by specific microRNAs, underlie the importance of the fine-tuning of p53 pathway, affecting the cell fate of damaged/transformed cells. The promising results of miRNAs-based therapeutic approaches in preclinical studies and their entrance in clinical trials demonstrate the feasibility of this strategy in several diseases, including cancer. Molecularly targeted drugs approved so far for HCC treatment show intrinsic or acquired resistances with disease progression in many cases, therefore the identification of effective and non-toxic agents for the treatment of HCC is actually an unmet clinical need. The knowledge of p53/miRNA inter-relations in HCC may provide useful elements for the identification of novel combined approaches in the context of the “personalized-medicine” era.

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.

IRAK1, a Target of miR-146b, Reduces Cell Aggressiveness of Human Papillary Thyroid Carcinoma

CONTEXT

MicroRNA (miR)-146b is overexpressed in papillary thyroid carcinoma (PTC) and is associated with extrathyroidal invasion, advanced tumor stage, and poor prognosis. However, the underlying mechanism of miR-146b in relation to its oncogenic behavior in PTC and its putative targets remain unknown.

OBJECTIVE

The purpose was to investigate IL-1 receptor-associated kinase 1 (IRAK1) as the potential miR-146b target gene and its involvement in PTC.

DESIGN

We used genome-wide microarray, computational analysis, and 3' UTR reporter gene assays to identify IRAK1 as a miR-146b target gene. In vitro gain/loss-of-function experiments were further performed to determine the effects of IRAK1 on proliferation, colony formation, and wound-healing in PTC cancer cell lines. Expression levels of miR-146b and IRAK1 of 50 cases of PTC and its adjacent normal thyroid specimens were assessed via qRT-PCR.

RESULTS

Microarray expression profile revealed that the mRNA level of IRAK1 gene was down-regulated by miR-146b. The 3' UTR of IRAK1 mRNA was found to be a molecular target of miR-146b posttranscriptional repression in BCPAP cells by reporter gene assays. MiR-146b promoted the migration and proliferation of PTC cells by down-regulating IRAK1 expression, whereas restoration of IRAK1 expression reversed this effect. In addition, the expression of IRAK1 mRNA was significantly lower in PTC clinical tissue samples than normal adjacent thyroid specimens and showed a strong inverse correlation with the expression of miR-146b in PTC specimens.

CONCLUSION

Our results demonstrated that IRAK1 is a direct target of miR-146b and has functional roles to inhibit various aggressive PTC cell activities. In conjunction with current therapeutic regimens, targeting the miR-146b-IRAK1 axis may provide a potential approach for PTC management.

Application of molecular biology of differentiated thyroid cancer for clinical prognostication

Although cancer outcome results from the interplay between genetics and environment, researchers are making a great effort for applying molecular biology in the prognostication of differentiated thyroid cancer (DTC). Nevertheless, role of molecular characterisation in the prognostic setting of DTC is still nebulous. Among the most common and well-characterised genetic alterations related to DTC, including mutations of BRAF and RAS and RET rearrangements, BRAF^V600E is the only mutation showing unequivocal association with clinical outcome. Unfortunately, its accuracy is strongly limited by low specificity. Recently, the introduction of next-generation sequencing techniques led to the identification of TERT promoter and TP53 mutations in DTC. These genetic abnormalities may identify a small subgroup of tumours with highly aggressive behaviour, thus improving specificity of molecular prognostication. Although knowledge of prognostic significance of TP53 mutations is still anecdotal, mutations of the TERT promoter have showed clear association with clinical outcome. Nevertheless, this genetic marker needs to be analysed according to a multigenetic model, as its prognostic effect becomes negligible when present in isolation. Given that any genetic alteration has demonstrated, taken alone, enough specificity, the co-occurrence of driving mutations is emerging as an independent genetic signature of aggressiveness, with possible future application in clinical practice. DTC prognostication may be empowered in the near future by non-tissue molecular prognosticators, including circulating BRAF^V600E and miRNAs. Although promising, use of these markers needs to be refined by the technical sight, and the actual prognostic value is still yet to be validated.

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.

miR-129 predicts prognosis and inhibits cell growth in human prostate carcinoma

MicroRNAs (miRNAs) are a class of small, well-conserved, non-coding RNAs that are increasingly identified as diagnostic and prognostic biomarkers in a number of cancers. Deregulated miR-129 is closely associated with tumorigenesis and cancer progression. However, the potential role of miR-129 in prostate cancer remains largely elusive. The present study investigated the role of miR-129 as a prognostic biomarker for tumor progression and clinical prognosis in prostate cancer patients. The examined prostate cancer tissues exhibited a significant reduction in miR-129 expression compared with the normal tissues (P=0.013). The expression levels of miR-129 were negatively correlated with histological grade (P<0.001), high preoperative prostate-specific antigen serum levels (P<0.001), pathological stage (P<0.001), high Gleason score (P<0.001), lymph node metastasis (P=0.002), angiolymphatic invasion (P=0.018), and biochemical recurrence (BCR; P=0.001). Use of the Kaplan-Meier analysis demonstrated that low miR-129 expression was closely associated with poorer BCR-free survival. Multivariate survival analysis indicated that miR-129 expression may be an independent prognostic marker for BCR-free survival in prostate cancer patients (P<0.001). Overexpression of miR-129 markedly attenuated prostate cancer cell growth by rescuing cell cycle-regulated protein expression. The present study suggests that miR-129 is downregulated in the cancerous tissues of prostate cancer patients, which was associated with poor BCR-free survival. Thus, it may be considered as a novel independent prognostic biomarker for prostate cancer. In addition, downregulation of miR-129 may serve a critical role in the proliferation of prostate cancer cells.

MicroRNAs in the thyroid

MicroRNAs (miRNAs) are small non-coding RNA comprising approximately 19-25 nucleotides. miRNAs can act as tumour suppressors or oncogenes, and aberrant expression of miRNAs has been reported in several human cancers and has been associated with cancer initiation and progression. Recent evidence suggests that miRNAs play a major role in thyroid carcinogenesis. In this review, we summarize the role of miRNAs in thyroid cancer and describe the oncogenic or tumour suppressor function of miRNAs as well as their clinical utility as prognostic or diagnostic markers in thyroid cancer.