Expression profiling of difficult-to-diagnose thyroid histologic subtypes shows distinct expression profiles and identify candidate diagnostic microRNAs

MicroRNA-126: Dual Role in Angiogenesis Dependent Diseases

BACKGROUND

MicroRNA-126, a microRNA implicated in blood vessel integrity and angiogenesis is significantly up/down regulated in different physiological and pathological conditions related to angiogenesis such as cardiovascular formation and angiogenesis dependent diseases. MicroRNA-126 plays a critical role in angiogenesis via regulating the proliferation, differentiation, migration, and apoptosis of angiogenesis related cells such as endothelial cells.

OBJECTIVE

The aim of this review is to investigate the molecular mechanisms and the effects of microRNA-126 on the process of angiogenesis in pathophysiological conditions.

METHODS

To conduct this review, related articles published between 2001 and 2019 were collected from the PubMed, Web of Science, Google Scholar, Scopus and Scientific Information Database using search terms such as microRNA-126, angiogenesis, cardiovascular disorders, hypoxia, VEFG-A, endothelial cells, VEGF pathway, and gene silencing. Then, the qualified articles were reviewed.

RESULTS

MicroRNA-126 regulates the response of endothelial cells to VEGF, through directly repressing multiple targets, including Sprouty-related EVH1 domain-containing protein 1 (SPRED1) and phosphoinositol-3 kinase regulatory subunit 2 (PIK3R2/p85-b). MicroRNA-126 -3p and microRNA-126 -5p have cell-type and strandspecific functions and also various targets in angiogenesis that lead to the regulation of angiogenesis via different pathways and consequently diverse responses.

CONCLUSION

MicroRNA-126 can bind to multiple targets and potentially be both positive and negative regulators of gene expression. Thus, microRNA-126 could cause the opposite biological effects depending on the context. As a result, understanding the different cellular pathways through which microRNA-126 regulates angiogenesis in various situations is a critical aspect in the development of novel and effective treatments for diseases with insufficient angiogenesis.

Implication of clinical target delineation for T1b/T2 thoracic esophageal squamous cell carcinoma based on the pattern of lymph node metastases

Aim: This study aimed to explore different patterns of lymph node metastases (LNM) in T1b and T2 thoracic esophageal squamous cell carcinoma (ESCC), and to further clarify its significance in radiotherapy target delineation. Materials & methods: Data of 1960 patients with T1b and T2 thoracic ESCC treated at different cancer centers were retrospectively analyzed. All patients underwent esophagectomy and lymphadenectomy. χ² test and multivariate analysis were applied for analyzing clinicopathological factors related to LNM. Results: Age, location, tumor length, T stage and pathological grade were significantly associated with LNM (p < 0.01). For T1b ESCC, LNM rates in all sites were below 15%. For T2 upper thoracic ESCC, LNM rates were over 15% in upper mediastinal (15.8%). For T2 middle thoracic ESCC, LNM rates were middle mediastinal (17.2%) and abdominal (15.5%). For T2 lower thoracic ESCC, LNM rates were lower mediastinal (24.9%) and abdominal (22.5%). Subgroup analysis of T2 middle thoracic ESCC demonstrated that for patients older than 60 years, tumor length <4 cm and tumors were well differentiated. The LNM rates for abdominal were 11.9, 12.7 and 9.9%. Conclusion: Given the different patterns of LNM between T1b and T2 thoracic ESCC, target delineation should be adjusted accordingly.

Knockdown of circPVT1 inhibits progression of papillary thyroid carcinoma by sponging miR-126

Background: Papillary thyroid carcinoma (PTC) is the most common thyroid cancer. Recent studies have reported that circular RNAs (circRNAs) play essential roles in human cancers, including PTC. However, the roles of circRNA plasmacytoma variant translocation 1 (PVT1) in PTC progression and its potential mechanism remain largely unknown. Methods: The expressions of circPVT1 and microRNA-126 (miR-126) were measured in PTC tissues and cells by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability, apoptosis, migration and invasion were detected in PTC cells by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), flow cytometry, Western blot or trans-well assays, respectively. The interaction between circPVT1 and miR-126 was explored by bioinformatics analysis, luciferase activity assay and RNA immunoprecipitation. A mouse xenograft model was established to investigate the role of circPVT1 in PTC progression in vivo. Results: High expression of circPVT1 was shown in PTC tissues and cells and was associated with poor outcomes of patients. Knockdown of circPVT1 suppressed viability, migration and invasion but induced apoptosis in PTC cells. miR-126 was bound to circPVT1 and reduced in PTC tissues and cells. Moreover, inhibition of miR-126 reversed the regulatory effect of the circPVT1 interference on viability, apoptosis, migration and invasion in PTC cells. Besides, circPVT1 knockdown attenuated tumor growth via up-regulating miR-126 in vivo. Conclusion: CircPVT1 knockdown inhibited PTC progression by sponging miR-126. This may indicate circPVT1 as a novel target for treatment of PTC.

Papillary thyroid carcinoma (PTC) is the most common thyroid cancer. Recent studies have reported that circular RNAs (circRNAs) play essential roles in human cancers, including PTC.

Down-regulated serum miR-126 is associated with aggressive progression and poor prognosis of gastric cancer

BACKGROUND

miR-126 functions as a tumor suppressor in gastric cancer (GC), however, the clinical significance of serum miR-126 in GC remains unclear.

OBJECTIVE

To investigate the associations of serum miR-126 level with the clinicopathological characteristics and prognosis of GC patients.

METHODS

Quantitative real-time polymerase chain reaction was performed to examine the expression levels of miR-126 in 338 GC patients' tissues and sera, and 50 healthy controls' sera. The associations of serum miR-126 with clinicopathological characteristics and clinical outcome were evaluated.

RESULTS

Compared with the matched adjacent non-tumor tissues and normal sera, miR-126 expression was significantly down-regulated in both tumor tissues and sera of GC patients. Importantly, there was a positive correlation between tissue and serum levels of miR-126 in GC patients. A reduced serum miR-126 level statistically correlated with aggressive clinicopathological characteristics, such as larger tumor size, deeper local invasion, more lymph node metastasis, advanced TNM stage, and poorer prognosis. Notably, multivariate analysis identified reduced serum miR-126 level as an independent predictor for the unfavorable prognosis of GC.

CONCLUSIONS

These results indicate for the first time that serum miR-126 may serve as a novel prognostic biomarker in GC.

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.

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.

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.

Candidate microRNAs as biomarkers of thyroid carcinoma: a systematic review, meta-analysis, and experimental validation

Thyroid cancer is one of the most common carcinomas of the endocrine system with an increasing incidence. A growing number of studies have focused on the diagnostic and prognostic values of dysregulated microRNAs (miRNAs) in thyroid carcinoma. However, differences in the measurement platforms, variations in lab protocols, and small sample sizes can make gene profiling data incomparable. A meta-review of the published studies that compared miRNA expression data of thyroid carcinoma and paired normal tissues was performed to identify potential miRNA biomarkers of thyroid carcinoma with the vote-counting strategy. Two hundred and thirty-six aberrantly expressed miRNAs were reported in 19 microRNA expression profiling studies. Among them, 138 miRNAs were reported in at least two studies. We also provided a meta-signature of differentially expressed miRNAs between individual histological types of thyroid carcinoma and normal tissues. The experimental validation with qRT-PCR analysis verified that the profiles identified with the meta-review approach could effectively discriminate papillary thyroid carcinoma tissues from paired noncancer tissues. The meta-review of miRNA expression profiling studies of thyroid carcinoma would provide information on candidate miRNAs that could potentially be used as biomarkers in thyroid carcinoma.

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.

Expression of miRNA and Occurrence of Distant Metastases in Patients with Hürthle Cell Carcinoma

Background. Hürthle cell thyroid carcinoma (HCTC) is a rare type of thyroid carcinoma. In the present study, we investigated whether the expression of miRNAs of interest is associated with the occurrence of metastases in patients with HCTC. Materials and Methods. In 39 patients with HCTC (22 with nonmetastatic and 17 with regional or distant metastatic disease), the expression levels of six miRNAs (miR-138, miR-183, miR-221, miR-222, miR-768-3p, and miR-885-5p) and U6 snRNA as endogenous control were determined in FFPE samples of primary tumor and normal thyroid tissue using TaqMan miRNA assays. Results. In patients with HCTC, miR-138 and miR-768-3p were downregulated in tumor samples compared to normal tissue (p = 0.013 and p = 0.010, resp.). These two miRNAs were also significantly downregulated in tumor samples of patients with metastatic disease (p = 0.030 and p = 0.048, resp.) but not in patients with nonmetastatic disease (p = 0.249 and p = 0.101, resp.). In patients with nonmetastatic disease, miR-221 and miR-885-5p were slightly, albeit significantly, upregulated in tumorous compared to normal tissue (p = 0.042 and p = 0.027, resp.). Conclusion. Expression of miRNA (miR-183, miR-221, and miR-885-5p) in tumor tissue is associated with the occurrence of distant metastases in patients with HCTC.

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.

Integrated Analysis of Thyroid Cancer Public Datasets Reveals Role of Post-Transcriptional Regulation on Tumor Progression by Targeting of Immune System Mediators

Papillary thyroid carcinoma (PTC) is a well-differentiated thyroid tumor that accounts for approximately 80% of thyroid cancer cases. On other hand, anaplastic thyroid carcinoma (ATC) is a less frequent, but aggressive subtype, with poor prognosis. MicroRNAs (miRNAs), small non-coding RNAs, have emerged as potent post-transcriptional regulators of gene expression, which modulate the expression of cancer-related genes. Computational analyses estimate that a single miRNA may modulate hundreds of mRNA targets and, at the same time, cooperate with others to regulate one single mRNA transcript. Due to the large number of predicted targets and possible interactions, only a small number of miRNAs have characterized biological roles, and the panorama of miRNA-mediated regulation in thyroid cancer remains to be understood. Taking into consideration the large amount of gene expression data deposited in public databases we aligned miRNA target prediction and gene expression data from public PTC and ATC datasets to construct a network of post-transcriptional regulation in thyroid cancer. After a gene set enrichment analysis we identified signaling pathways and biological processes potentially modulated by the miRNAs deregulated in PTC and ATC. Our results show miRNA-mRNA interaction that could contribute with the de-regulation of key tumor-host mediators, such as extra-cellular matrix molecules, interleukins and interleukin receptors, which could drive a more aggressive behavior and tumor progression. Moreover, our analysis through The Cancer Genome Atlas (TCGA) database revealed that aberrant expression of ECM and cytokines genes is frequent in PTC and is associated with aggressive behavior and decreased overall survival rate. In conclusion, we shed light on the post-transcriptional regulation of gene expression in differentiated and undifferentiated thyroid cancers, revealing a potential role of miRNAs in modulation of tumor-host interaction molecules, particularly ECM molecules and immune system mediators, which could stimulate crosstalk between tumors and the immune system to generate a more aggressive behavior. We propose a novel putative miRNA:mRNA network that could lead to a new path toward functional studies.

Promoter mutation of tumor suppressor microRNA-7 is associated with poor prognosis of lung cancer

The significance of promoter mutations of microRNAs (miRNAs) in lung cancer is poorly understood. Recent evidence demonstrated that miRNA-7 (miR-7), a unique member of the miRNA family, exhibited decreased expression and has emerged as an important regulator in lung tumorigenesis. However, the mechanism underlying the downregulation of miR-7 in lung cancer remains largely unknown. In this study, we investigated the sites of mutation of the miR-7 promoter in lung cancer tissues using DNA sequencing. We identified a G→C change at the -617 site (25/39, 64.1%) and an A→G change at the -604 site (20/39, 51.3%) in the miR-7 promoter region in lung cancer tissues. Moreover, the expression of miR-7 in cancer tissue with promoter site mutations was lower compared with that in cancer tissue without mutations (P<0.05). Furthermore, we demonstrated that mutations at these sites may decrease the activity of the miR-7 promoter and alter the expression of miR-7. Notably, mutations at these sites of the miR-7 promoter were found to be closely associated with poor prognosis of lung cancer patients (P=0.037). These data may provide novel insight on the altered expression of specific miRNA molecules in lung cancer and ultimately prove to be helpful in the development of prognostic and therapeutic strategies against lung cancer.

miR-126-3p Inhibits Thyroid Cancer Cell Growth and Metastasis, and Is Associated with Aggressive Thyroid Cancer

BACKGROUND

Previous studies have shown that microRNAs are dysregulated in thyroid cancer and play important roles in the post-transcriptional regulation of target oncogenes and/or tumor suppressor genes.

METHODOLOGY/PRINCIPAL FINDINGS

We studied the function of miR-126-3p in thyroid cancer cells, and as a marker of disease aggressiveness. We found that miR-126-3p expression was significantly lower in larger tumors, in tumor samples with extrathyroidal invasion, and in higher risk group thyroid cancer in 496 papillary thyroid cancer samples from The Cancer Genome Atlas study cohort. In an independent sample set, lower miR-126-3p expression was observed in follicular thyroid cancers (which have capsular and angioinvasion) as compared to follicular adenomas. Mechanistically, ectopic overexpression of miR-126-3p significantly inhibited thyroid cancer cell proliferation, in vitro (p<0.01) and in vivo (p<0.01), colony formation (p<0.01), tumor spheroid formation (p<0.05), cellular migration (p<0.05), VEGF secretion and endothelial tube formation, and lung metastasis in vivo. We found 14 predicted target genes, which were significantly altered upon miR-126-3p transfection in thyroid cancer cells, and which are involved in cancer biology. Of these 14 genes, SLC7A5 and ADAM9 were confirmed to be inhibited by miR-126-3p overexpression and to be direct targets of miR-136-3p.

CONCLUSIONS/SIGNIFICANCE

To our knowledge, this is the first study to demonstrate that miR-126-3p has a tumor-suppressive function in thyroid cancer cells, and is associated with aggressive disease phenotype.

miR-126 inhibits papillary thyroid carcinoma growth by targeting LRP6

microRNA-126 (miR-126) has been reported to play tumor suppressor roles in various types of cancers. Although it has been reported that miR-126 expression is downregulated in papillary thyroid carcinoma (PTC), the precise role and underlying molecular mechanism of miR-126 in PTC remains unclear. Therefore, the aims of the present study were to investigate the role and potential mechanism of miR-126 in tumorigenicity of PTC in vivo and in vitro. We observed that the miR-126 expression level was significantly downregulated in PTC tissue and PTC cell lines, the aberrant expression of miR-126 was correlated with lymph node metastasis, tumor size and TNM stage. We also showed that restoration of miR-126 in PTC cells inhibited cell proliferation, colony formations, migration and invasion, promoted cell apoptosis and cell cycle arrest at G1 stage in vitro, as well as inhibited tumor growth and decreased tumor volume and weight in vivo. Furthermore, low-density lipoprotein receptor‑related protein 6 (LRP6), a regulator of the Wnt/β‑catenin signaling cascade, was identified as a crucial target gene of miR-126. Overexpression of miR-126 inhibited LP6 expression on mRNA and protein levels, and deactivate Wnt/β-catenin signaling pathway. These results suggested that miR-126 functions as a tumor-suppressive miRNA by targeting LRP6 regulating Wnt/β-catenin signaling pathway and represents a therapeutic target for PTC.

Molecular Assays in Cytopathology for Thyroid Cancer

Background

Despite lack of adequate, validated, independently performed clinical studies, several molecular tests are commercially available on the market and are being used on indeterminate thyroid nodules to guide patient-care decisions.

Methods

We summarize the current evidence on the role and limitations of molecular tests used in combination with thyroid cytopathology to refine the presurgical diagnosis of thyroid nodules.

Results

The clinical performance of molecular tests depends on the pretest risk of malignancy within the specific cytological group being assessed. This risk is variable and should be assessed at each institution to optimize the selection of the molecular test and the interpretation of its results. Next-generation sequencing has increased the sensitivity of oncogene panels while maintaining high specificity. Tests assessing the gene expression pattern have shown promising results, with high sensitivity but low specificity. The impacts of molecular markers on clinical practice remains in flux and their effect on health care costs remains poorly understood.

Conclusions

Further large, independent, confirmatory, clinical validation studies and real-world, cost-effectiveness studies are necessary before the widespread adoption of these tests can be endorsed as standard of care.

Papillary thyroid cancer-derived exosomes contain miRNA-146b and miRNA-222

BACKGROUND

With the increasing diagnosis of indolent papillary thyroid cancer (PTC), the task of identifying those likely to suffer from recurrence is becoming ever more challenging. MicroRNA (miRNA/miR) in the circulation has been demonstrated as potential biomarkers of recurrence in PTC. This study aimed to investigate in vitro if extracellular miRNAs are contained in exosomes, and their potential effect on other cells.

METHODS

TPC-1 (PTC) and NTHY (normal thyroid follicular) cell lines were treated with exosome isolates and conditioned medium (CM), both containing miR-146b and miR-222. The changes in proliferation over a 72-h period of TPC-1 and NTHY were compared. Student t-test and analysis of variance were used for significance testing, and P < 0.05 was considered significant.

RESULTS

Exosomes derived from TPC-1 cells were demonstrated to contain miR-146b and miR-222 in relative abundance. These exosomes caused a negative proliferative effect on both TPC-1 and NTHY cells. Exosomes derived from NTHY cells did not exert a significant proliferative effect on either cell line. CM from both cell types caused an initial increase in TPC-1 proliferation at 24 h. No significant change in proliferation was seen with NTHY cells when treated with either of the CM.

CONCLUSIONS

The results showed that PTC cells overexpress miR-146b and miR-222 in exosomes; and that factors released by both normal thyroid and PTC cells alter proliferation of other cells in a complex manner. The intercellular interactions were likely conferred in part by exosomal miRNA, which can potentially be developed as biomarkers of PTC recurrence.

miR-199a-3p displays tumor suppressor functions in papillary thyroid carcinoma

Thyroid cancer incidence is rapidly increasing. Papillary Thyroid Carcinoma (PTC), the most frequent hystotype, usually displays good prognosis, but no effective therapeutic options are available for the fraction of progressive PTC patients. BRAF and RET/PTC are the most frequent driving genetic lesions identified in PTC. We developed two complementary in vitro models based on RET/PTC1 oncogene, starting from the hypothesis that miRNAs modulated by a driving PTC-oncogene are likely to have a role in thyroid neoplastic processes. Through this strategy, we identified a panel of deregulated miRNAs. Among these we focused on miR-199a-3p and showed its under-expression in PTC specimens and cell lines. We demonstrated that miR-199a-3p restoration in PTC cells reduces MET and mTOR protein levels, impairs migration and proliferation and, more interesting, induces lethality through an unusual form of cell death similar to methuosis, caused by macropinocytosis dysregulation. Silencing MET or mTOR, both involved in survival pathways, does not recapitulate miR-199a-3p-induced cell lethality, thus suggesting that the cooperative regulation of multiple gene targets is necessary. Integrated analysis of miR-199a-3p targets unveils interesting networks including HGF and macropinocytosis pathways. Overall our results indicate miR-199a-3p as a tumor suppressor miRNA in PTC.

Effect of BRAF mutational status on expression profiles in conventional papillary thyroid carcinomas

BACKGROUND

Whereas 40 % to 70 % of papillary thyroid carcinomas (PTCs) are characterized by a BRAF mutation (BRAFmut), unified biomarkers for the genetically heterogeneous group of BRAF wild type (BRAFwt) PTCs are not established yet. Using state-of-the-art technology we compared RNA expression profiles between conventional BRAFwt and BRAFmut PTCs.

METHODS

Microarrays covering 36,079 reference sequences were used to generate whole transcript expression profiles in 11 BRAFwt PTCs including five micro PTCs, 14 BRAFmut PTCs, and 7 normal thyroid specimens. A p-value with a false discovery rate (FDR) < 0.05 and a fold change > 2 were used as a threshold of significance for differential expression. Network and pathway utilities were employed to interpret significance of expression data. BRAF mutational status was established by direct sequencing the hotspot region of exon 15.

RESULTS

We identified 237 annotated genes that were significantly differentially expressed between BRAFwt and BRAFmut PTCs. Of these, 110 genes were down- and 127 were upregulated in BRAFwt compared to BRAFmut PTCs. A number of molecules involved in thyroid hormone metabolism including thyroid peroxidase (TPO) were differentially expressed between both groups. Among cancer-associated molecules were ERBB3 that was downregulated and ERBB4 that was upregulated in BRAFwt PTCs. Two microRNAs were significantly differentially expressed of which miR492 bears predicted functions relevant to thyroid-specific molecules. The protein kinase A (PKA) and the G protein-coupled receptor pathways were identified as significantly related signaling cascades to the gene set of 237 genes. Furthermore, a network of interacting molecules was predicted on basis of the differentially expressed gene set.

CONCLUSIONS

The expression study focusing on affected genes that are differentially expressed between BRAFwt and BRAFmut conventional PTCs identified a number of molecules which are connected in a network and affect important canonical pathways. The identified gene set adds to our understanding of the tumor biology of BRAFwt and BRAFmut PTCs and contains genes/biomarkers of interest.

A two miRNA classifier differentiates follicular thyroid carcinomas from follicular thyroid adenomas

The inherent diagnostic limitations of thyroid fine needle aspiration (FNA), especially in the "indeterminate" category, can be partially overcome by molecular analyses. We aimed at the identification of miRNAs that could be used to improve the discrimination of indeterminate FNAs. miRNA expression profiling was performed for 17 follicular carcinomas (FTCs) and 8 follicular adenomas (FAs). The microarray results underwent cross-comparison using three additional microarray data sets. Candidate miRNAs were validated by qPCR in an independent set of 32 FTCs and 46 FAs. Sixty-eight differentially expressed miRNAs were identified. Thirteen miRNAs could be confirmed by cross comparison. A two-miRNA-classifier was established improving the diagnostic applicability and resulted in a sensitivity of 82% and a specificity of 49%. We present a classifier that has the potential to be successfully evaluated in cytology material for its capability to discriminate (mutation negative) indeterminate cytologies and thereby improving the pre-surgical diagnostics of thyroid nodules.

MicroRNA-638 inhibits cell proliferation, invasion and regulates cell cycle by targeting tetraspanin 1 in human colorectal carcinoma

The expression of miR-638 was found downregulated in colorectal carcinoma (CRC) in our previous study. However, the role of miR-638 in CRC remains unknown. The aim of this study was to determine the function and mechanism of miR-638 in CRC. Here, we verified that miR-638 was frequently downregulated in CRC tissues compared with corresponding noncancerous tissues (NCTs) in an expanded CRC cohort, and survival analysis showed that the downregulation of miR-638 in CRC was associated with poor prognoses. The ectopic expression of miR-638 inhibited CRC cell proliferation, invasion and arrest the cell cycle in G1 phase, whereas the repression of miR-638 significantly promoted CRC cell growth, invasion and cell cycle G1/S transition. Subsequent mechanism analyses revealed that miR-638 inhibited CRC cell growth, invasion and cell cycle progression by targeting TSPAN1. TSPAN1 protein levels were upregulated in CRC samples and were inversely correlated with miR-638 levels. More importantly, high TSPAN1 expression levels in CRC tissues predicted poor overall survival, and appears to be an independent prognostic factor for CRC survival. Furthermore, CpG island methylation analyses revealed that the miR-638 promoter was hypermethylated in CRC and that attenuating promoter methylation was sufficient to restore miR-638 expression in CRC cells. Taken together, our current data demonstrate that miR-638 functions as a tumor suppressor in human CRC by inhibiting TSPAN1, and that TSPAN1 is a potential prognostic factor for CRC.

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.

Better understanding in the differentiation of thyroid follicular adenoma, follicular carcinoma, and follicular variant of papillary carcinoma: a retrospective study

Background. To evaluate the role of ultrasonography (US), US-guided fine-needle aspiration (USFNA) and intraoperative frozen section (FS) in follicular neoplasm. Methods. US features, USFNA cytology, and FS results were compared based on the pathology results of patients with follicular adenoma (FA), follicular carcinoma (FC), and follicular variant of papillary thyroid carcinoma (FVPTC). Results. FC and FVPTC showed significantly higher rates of suspicious US features (P < 0.05) and positive findings on either US or cytology, 80.0% and 90.7%, compared to FA, 64.5% (P = 0.001). Intraoperative FS showed higher malignant rates in FVPTC and FC (81.8% and 75.0%, resp.), compared to FA (3.8%, P < 0.001). Conclusion. Suspicious US features were more significantly seen in FC and FVPTC compared to FA. Intraoperative FS is useful in the differential diagnosis of these lesions and supplements cytology results of USFNA.

Molecular diagnosis for indeterminate thyroid nodules on fine needle aspiration: advances and limitations

Indeterminate thyroid lesions are diagnosed in up to 30% of fine needle aspirations. These nodules harbor malignancy in more than 25% of cases, and hemithyroidectomy or total thyroidectomy has therefore been advocated in order to achieve definitive diagnosis. Recently, many molecular markers have been investigated in an attempt to increase diagnostic accuracy of indeterminate fine needle aspiration cytology and thereby avoid unnecessary complications and costs associated with thyroid surgery. Somatic mutation testing, mRNA gene expression platforms, protein immunocytochemistry and miRNA panels have improved the diagnostic accuracy of indeterminate thyroid nodules, and although no test is perfectly accurate, in the authors' opinion, these methods will most certainly become an important part of the diagnostic tools for clinicians and cytopathologists in the future.

Diagnostic value of B-RAF(V600E) in difficult-to-diagnose thyroid nodules using fine-needle aspiration: systematic review and meta-analysis

Fine-needle aspiration (FNA) is routinely used in the preoperative evaluation of thyroid nodules. However, approximately 5-20% of thyroid nodules are considered indeterminate or suspicious cases that do not meet clinical standards. The B-RAF(V600E) mutation has been reported in FNA specimens. We conducted a systematic review to evaluate the diagnostic value of testing for B-RAF(V600E) in thyroid nodules that are difficult to diagnose by FNA. A systematic literature search was performed from January 1, 2002 to June 30, 2012. Articles were obtained by searching two electronic databases (MEDLINE and EMBASE), hand searching selected journals, and contacting authors. Article quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. Sensitivity, specificity, and other measures of accuracy were pooled using random effects models. Summary receiver operating characteristic (SROC) curves were used to summarize overall diagnostic accuracy. A total of 16 studies incorporating 1131 patients were included in a meta-analysis on diagnostic accuracy of B-RAF(V600E) tests. Pooled sensitivity was 0.60 (95% confidence interval [CI]: 0.556-0.634), pooled specificity was 0.99 (95% CI 0.976-0.997), and the area under the curve of the SROC curve was 0.8376. Q index value was 0.7696. Our data suggest a potentially useful adjunct to evaluating thyroid nodules that are difficult to diagnose. The B-RAF(V600E) test has a high positive predictive value and could help clinicians formulate a more individualized treatment schedule. When supplemented with other noninvasive test methods, the B-RAF(V600E) test could be a powerful adjunct with extensive clinical applications.

Five Top Stories in Cytopathology

Context.—Cytology relies heavily on morphology to make diagnoses, and morphologic criteria have not changed much in recent years. The field is being shaped predominantly by new techniques for imaging and for acquiring and processing samples, advances in molecular diagnosis and therapeutics, and regulatory issues.

Objective.—To review the importance of classical morphology in the future of cytopathology, to identify areas in which cytology is expanding or contracting in its scope, and to identify factors that are shaping the field.

Data Sources.—Literature review.

Conclusions.—Five stories paint a picture in which classical cytomorphology will continue to have essential importance, both for diagnosis and for improving our understanding of cancer biology. New endoscopy and imaging techniques are replacing surgical biopsies with cytology samples. New molecularly targeted therapies offer a chance for cytology to play a major role, but they pose new challenges. New molecular tests have the potential to synergize with, but not replace, morphologic interpretation of thyroid fine-needle aspirations. Ultrasound-guided fine-needle aspiration performed by cytopathologists is opening a new field of “interventional cytopathology” with unique value. For the productive evolution of the field, it will be important for cytopathologists to play an active role in clinical trials that document the ability of cytology to achieve cost-effective health care outcomes.

Expressions of miRNAs in papillary thyroid carcinoma and their associations with the BRAFV600E mutation

OBJECTIVE

Alterations in microRNA (miRNA) expression have been described in thyroid tumors, suggesting a role for miRNAs in thyroid carcinogenesis. BRAF(V600E) is the most frequently identified genetic alteration in papillary thyroid carcinoma (PTC). We investigated the link between BRAF(V600E) status and the expression of miRNAs in PTC and analyzed the associations of these factors with clinicopathological characteristics.

DESIGN AND METHODS

Prospective study of patients who underwent thyroid surgery between October 8, 2008 and November 1, 2010. BRAF(V600E) status was determined by mutant allele-specific amplification PCR and direct sequencing of exon 15 of the BRAF gene in 69 PTC tissues and 69 respective paracancerous normal thyroid tissues. Initially, miRNA expression was analyzed in 12 PTC tissues and three associated paracancerous tissues using a miRNA microarray. miRNAs differentially expressed between BRAF(V600E)-positive and -negative PTC tissues were then validated by real-time quantitative PCR on 69 PTC tissues and 69 paracancerous tissues. We also explored the associations between BRAF(V600E) status or differential miRNA expression and clinicopathological characteristics.

RESULTS

The mutation rate of BRAF(V600E) in PTC was 47.8%. Twelve miRNAs were upregulated and six were downregulated in PTC tissues, among which miR-15a, 15a*, 34a*, 34b*, 551b, 873, 876-3p, and 1274a were first identified. miR-21* and 203 were significantly dysregulated (P<0.05) in PTC tissues with BRAF(V600E). Additionally, there were significant associations (P<0.05) between BRAF(V600E) and a higher tumor-node-metastasis staging (III/IV), and between miR-21* over-expression and lymph node metastasis.

CONCLUSIONS

We identified two miRNAs that are differentially expressed in PTC tissues with BRAF(V600E) and revealed their associations with clinicopathological features. These findings may lead to the development of a potential diagnostic biomarker or prognostic indicator of PTC.

MicroRNA expression profiles in differentiated thyroid cancer, a review

MicroRNAs (miRNAs) are a class of short endogenous non-coding RNAs regulating gene expression in many biological processes, including proliferation, apoptosis and differentiation. The deregulation of miRNA expression is believed to be an important regulator of tumor development and progression of thyroid cancer. In this review, we discussed important roles and expression profiles of miRNA in differentiated thyroid cancer (DTC) as well as the promising implication in clinical practice.

Overexpression of miR-221 is associated with aggressive clinicopathologic characteristics and the BRAF mutation in papillary thyroid carcinomas

Correlation between clinicopathogenetic features and the expression of specific miRNAs is unclear in papillary thyroid carcinoma (PTC). We therefore sought to assess whether miR-221 was associated with aggressive clinicopathologic characteristics and the BRAF mutation. We studied the expression levels of miR-221 using northern blot quantitated by scion image in 51 cases of PTCs. The status of BRAF of PTCs was analyzed through direct DNA sequencing. Mann-Whitney U test was used to analyze different expression of miR-221 in PTCs with distinct clinicopathogenetic characteristics including gender, age, tumor size, multifocality, extrathyroidal invasion, disease stages, node metastasis, and BRAF status. Compared with the normal thyroid tissues, the relative expression of miR-221 in tumor tissues was significantly upregulated (p < 0.001). Overexpression of miR-221 was significantly associated with extrathyroidal invasion (p = 0.001), lymph node metastasis (p = 0.046), advanced disease stages III-IV (p = 0.001), and the BRAF mutation (p = 0.014). While among BRAF wild tumors, miR-221 was only associated with extarthyroidal invasion, it showed strong association with all above aggressive features among BRAF mutation tumors. MiR-221 may be of potential importance in determining the aggressive properties of PTCs including the BRAF mutation, and it may further refine the risk stratification by BRAF mutation in PTCs.

The biology and the genetics of Hurthle cell tumors of the thyroid

The biology and the genetics of Hürthle cell tumors are reviewed starting from the characterization and differential diagnosis of the numerous benign and malignant, neoplastic and nonneoplastic lesions of the thyroid in which Hürthle cell transformation is frequently observed. The clinicopathologic and molecular evidence obtained from the comparative study of the aforementioned conditions indicate that Hürthle cell appearance represents a phenotype that is superimposed on the genotypic and conventional histopathologic features of the tumors. Hürthle cell tumors differ from their non-Hürthle counterparts regarding the prevalence of large deletions of mitochondrial DNA (mtDNA), mutations of mtDNA genes coding for oxidative phosphorylation (OXPHOS) proteins (namely mutations of complex I subunit genes) and mutations of nuclear genes coding also for mitochondrial OXPHOS proteins. Such mitochondrial alterations lead to energy production defects in Hürthle cell tumors; the increased proliferation of mitochondria may reflect a compensatory mechanism for such defects and is associated with the overexpression of factors involved in mitochondrial biogenesis. The mitochondrial abnormalities are also thought to play a major role in the predisposition for necrosis instead of apoptosis which seems to be blocked in most Hürthle cell tumors. Finally, the results obtained in experimental models using cybrid cell lines and the data obtained from histopathologic and molecular studies of familial Hürthle cell tumors are used, together with the aforementioned genetic and epigenetic alterations, to progress in the understanding of the mechanisms through which mitochondrial abnormalities may be involved in the different steps of thyroid carcinogenesis, from tumor initiation to metastization.

Downregulation of miR-126 induces angiogenesis and lymphangiogenesis by activation of VEGF-A in oral cancer

Background:

MicroRNA (miRNA)-126 (miR-126) is an endothelial-specific miRNA located within intron 7 of epidermal growth factor-like domain 7 (EGFL7). However, the role of miR-126 in cancer is controversial.

Methods:

We examined the function of miR-126 in oral squamous cell carcinoma (OSCC) cells. Furthermore, a series of 118 cases with OSCC were evaluated for the expression levels of miR-126.

Results:

MicroRNA-126 (miR-126) was associated with cell growth and regulation of vascular endothelial growth factor-A activity, and demethylation treatment increased expression levels of miR-126 and EGFL7 in OSCC cells. A significant association was found between miR-126 expression and tumour progression, nodal metastasis, vessel density, or poor prognosis in OSCC cases. In the multivariate analysis, decreased miR-126 expression was strongly correlated with disease-free survival.

Conclusion:

The present results suggest that miR-126 might be a useful diagnostic and therapeutic target in OSCC.

MicroRNA as a diagnostic tool in fine-needle aspiration biopsy of thyroid nodules

Thyroid cancer accounts for 1.5% of all malignancies in the U.S., and it is the most common endocrine malignancy. Detection of thyroid cancer mostly relies on evaluation of thyroid nodules, which are very common but only 5%-7% harbor malignancy. Fine-needle aspiration biopsy (FNAB) is currently the most important tool for the evaluation of thyroid nodules; however, it is limited in that it provides only a cytology assessment of the aspirated cells, and indeterminate diagnoses are present in up to 30% of FNAB results. This limitation can be overcome by the molecular analysis of FNAB, and more specifically with the use of microRNAs (miRs). miRs constitute a class of endogenous small noncoding RNA fragments that regulate gene expression, and in vitro studies have shown that miRs play a significant role in cancer and regulate major processes, such as proliferation, differentiation, and cell death. Several studies have investigated the miR expression signature in different thyroid cancers, and data support its use as a diagnostic tool that is highly accurate for thyroid nodules. The purpose of this study is to review the accumulated data on miR dysregulation in the different thyroid cancer types, critically assess its diagnostic utility, and conclude with future study strategies.

MicroRNAs: molecular features and role in cancer

microRNAs (miRNAs) are small noncoding endogenously produced RNAs that play key roles in controlling the expression of many cellular proteins. Once they are recruited and incorporated into a ribonucleoprotein complex miRISC, they can target specific mRNAs in a miRNA sequence-dependent process and interfere in the translation into proteins of the targeted mRNAs via several mechanisms. Consequently, miRNAs can regulate many cellular pathways and processes. Dysregulation of their physiological roles may largely contribute to disease. In particular, in cancer, miRNAs can be involved in the deregulation of the expression of important genes that play key roles in tumorigenesis, tumor development, and angiogenesis and have oncogenic or tumor suppressor roles. This review focuses on the biogenesis and maturation of miRNAs, their mechanisms of gene regulation, and the way their expression is deregulated in cancer. The involvement of miRNAs in several oncogenic pathways such as angiogenesis and apoptosis, and in the inter-cellular dialog mediated by miRNA-loaded exosomes as well as the development of new therapeutical strategies based on miRNAs will be discussed.

Evaluation of candidate diagnostic microRNAs in thyroid fine-needle aspiration biopsy samples

BACKGROUND

Thyroid cancer diagnosis in the United States has increased by 2.3-folds in the last three decades. Up to 30% of thyroid fine-needle aspiration biopsy (FNAB) results are inconclusive. Several differentially expressed microRNAs (miRNAs) have been identified as candidate diagnostic markers for thyroid nodules. We hypothesized that these differentially expressed miRNAs may improve the accuracy of FNAB in difficult to diagnose thyroid nodules.

METHODS

Expression levels of four miRNAs (miR-7, -126, -374a, and let-7g) were analyzed using quantitative real-time reverse transcription-polymerase chain reaction in 95 FNAB samples as the training set. A predictor model was formulated based on the most differentially expressed miRNA (miR-7) ΔCt value and the model was applied on a separate cohort of 59 FNAB samples as the validation set.

RESULTS

miR-7 was the best predictor to distinguish benign from malignant thyroid FNAB samples. The other three miRNAs were co-expressed and did not significantly contribute to the predictor model. miR-7 had a sensitivity of 100%, specificity of 29%, positive predictive value (PPV) of 36%, negative predictive value (NPV) of 100%, and overall accuracy of 76% when applied to the validation set. In subgroup analysis of preoperative nondiagnostic, indeterminate, or suspicious FNAB samples, the predictor model had an overall accuracy of 37% with sensitivity of 100%, specificity of 20%, PPV of 25%, and NPV of 100%.

CONCLUSIONS

miR-7 may be a helpful adjunct marker to thyroid FNAB in tumor types which are inconclusive. Given the high NPV of miR-7, a patient with a benign result based on the predictor model may be followed as opposed to performing an immediate diagnostic thyroidectomy. Future prospective clinical trials evaluating its accuracy in a larger cohort are warranted to determine its clinical utility.

A panel of four miRNAs accurately differentiates malignant from benign indeterminate thyroid lesions on fine needle aspiration

PURPOSE

Indeterminate thyroid lesions on fine needle aspiration (FNA) harbor malignancy in about 25% of cases. Hemi- or total thyroidectomy has, therefore, been routinely advocated for definitive diagnosis. In this study, we analyzed miRNA expression in indeterminate FNA samples and determined its prognostic effects on final pathologic diagnosis.

EXPERIMENTAL DESIGN

A predictive model was derived using 29 ex vivo indeterminate thyroid lesions on FNA to differentiate malignant from benign tumors at a tertiary referral center and validated on an independent set of 72 prospectively collected in vivo FNA samples. Expression levels of miR-222, miR-328, miR-197, miR-21, miR-181a, and miR-146b were determined using reverse transcriptase PCR. A statistical model was developed using the support vector machine (SVM) approach.

RESULTS

A SVM model with four miRNAs (miR-222, miR-328, miR-197, and miR-21) was initially estimated to have 86% predictive accuracy using cross-validation. When applied to the 72 independent in vivo validation samples, performance was actually better than predicted with a sensitivity of 100% and specificity of 86%, for a predictive accuracy of 90% in differentiating malignant from benign indeterminate lesions. When Hurthle cell lesions were excluded, overall accuracy improved to 97% with 100% sensitivity and 95% specificity.

CONCLUSIONS

This study shows that that the expression of miR-222, miR-328, miR-197, and miR-21 combined in a predictive model is accurate at differentiating malignant from benign indeterminate thyroid lesions on FNA. These findings suggest that FNA miRNA analysis could be a useful adjunct in the management algorithm of patients with thyroid nodules.

The molecular diagnosis and management of thyroid neoplasms

PURPOSE OF REVIEW

The molecular work-up of thyroid nodules on fine needle aspiration (FNA) cytology samples has given clinicians a new level of diagnostic information. We focus this review on the molecular techniques used in the diagnosis of thyroid cancer, especially BRAF, and the resulting management considerations that are raised.

RECENT FINDINGS

BRAF testing offers both diagnostic and prognostic information; it has been used along with the Bethesda Thyroid FNA Classification System to offer preoperative guidance in the management of thyroid nodules. Various authors have successfully utilized molecular panels on cytologic specimens including mutations and rearrangements such as RAS and RET/PTC. Preoperative mutation detection allows initial management decisions to be made with a greater clinical confidence.

SUMMARY

BRAF molecular testing holds promise as a possible diagnostic tool for indeterminate FNAs, and as a determinant for planning initial clinical management of thyroid nodules. Further developments in the molecular approach to thyroid cancer are expected to allow greater individualization of patient care.

The significance of hurthle cells in thyroid disease

Hürthle cells (HCs) and HC change, along with the frequently employed synonyms "oncocytes/oncocytic change" or "oxyphils/oxyphilic change," are not infrequently described on fine-needle aspiration biopsy (FNAB) reports of thyroid lesions. The description of HCs on FNAB reports may cause significant concern to the clinician; however, placing the finding in the appropriate clinical context may alleviate some anxiety. Not all oxyphilic cells are true HCs and not every aspirate containing HCs is or should be considered equivalent to an HC neoplasm (HCN). There are many benign thyroid lesions associated with HCs or HC change. For clinicians, it may be difficult to discern the significance of these findings and to determine an appropriate course of action. A skilled and experienced cytopathologist is invaluable in discriminating the subtle features that distinguish these lesions from those warranting a more aggressive approach. The diagnosis of HC carcinoma relies on histopathologic scrutiny and evidence of capsular and/or vascular invasion or metastasis to lymph nodes or distant organs. Many investigators have sought clinical, radiographic, cytological, genetic, and other factors to attempt to discriminate preoperatively between benign and malignant HCNs. To date, none have been definitively proven to be reliable. For now, because of the inability to determine the benign or malignant nature of such neoplasms based on cytology alone, a surgical approach is warranted.