The role of microRNAs in thyroid carcinomas

Thyroid cancers (TCs) are the most common malignancies of endocrine organs. They originate from cells of different origin within the thyroid gland, which is located at the base of the neck. Several forms of TCs have been classified and great variability is observed in molecular, cellular and clinical features. The most common forms have favorable prognosis but a number of very aggressive TCs, which are characterized by a less differentiated cellular phenotype, have no effective treatment at the moment. While TC causes are not completely understood, many genetic factors involved in their onset have been discovered. In particular, activating mutations of BRAF, RET or RAS genes are known to be specifically associated with TC initiation, progression and outcome. The involvement of microRNAs in thyroid neoplasms has recently changed the paradigm for biomarker discovery in TC, suggesting that these small non-coding RNAs could be used to develop, refine or strengthen strategies for diagnosis and management of TCs. In this review, the importance of microRNA profiling in TC is explored suggesting that these molecules can be included in procedures that can perform better than any known clinical index in the identification of adverse outcomes

Reduced expression of THRβ in papillary thyroid carcinomas: relationship with BRAF mutation, aggressiveness and miR expression

Purpose Down-regulation of thyroid hormone receptor beta (THRβ) gene has been described in several human malignancies, including thyroid cancer. In this study, we analyzed THRβ mRNA expression in surgical specimens from a series of human papillary thyroid carcinomas (PTCs), characterized by their genotypic and clinical–biological features. Methods Thirty-six PTCs were divided into two groups according to the 2009 American Thyroid Association risk classification (17 low, 19 intermediate), and each group was divided into subgroups based on the presence or absence of the BRAFV600E mutation (21 BRAF mutated, 15 BRAF wild type). Gene expression was analyzed using fluidic cards containing probes and primers specific for the THRβ gene, as well as for genes of thyroperoxidase (TPO), sodium/iodide symporter (NIS), thyroglobulin (Tg) and thyroid stimulating hormone receptor (TSH-R) and for some miRNAs involved in thyroid neoplasia and targeting THRβ. The mRNA levels of each tumor tissue were compared with their correspondent normal counterpart. Results THRβ transcript was down-regulated in all PTCs examined. No significant differences were found between intermediate- vs low-risk PTCs patients, and BRAF-mutated vs BRAF wild-type groups. THRβ expression was directly correlated with NIS, TPO, Tg and TSH-R, and inversely correlated to miR-21, -146a, -181a and -221 expression. Conclusions Our results demonstrate that down-regulation of THRβ is a common feature of PTCs. While it is not associated with a more aggressive phenotype of PTC, it correlates with the reduction of all the markers of differentiation and is associated with overexpression of some miRNAs supposed to play a role in thyroid tumorigenesis

Fibronectin-1 expression is increased in aggressive thyroid cancer and favors the migration and invasion of cancer cells

n this study we analyzed the expression levels of markers of epithelial-to-mesenchymal transition (EMT) in several papillary thyroid carcinomas (PTCs) and the relation with tumor genotypes and clinicopathological characteristics. The role of fibronectin-1 (FN1) was investigated by analyzing the effects of FN1 silencing in two human thyroid cancer cell lines. Most of EMT markers were significantly over-expressed in a group of 36 PTCs. In particular, FN1 mRNA levels were higher in tumor vs non-tumor tissue (117.3, p < 0.001) and also in aggressive and BRAF(V600E) samples. Similar results were observed (and confirmed at the protein level) when FN1 expression was analyzed in a validation group of 50 PTCs and six lymph node (LN) metastases. Silencing of FN1 in TPC-1 and BCPAP thyroid cancer cells significantly reduced proliferation, adhesion, migration, and invasion in both cell lines. Collectively, our data indicate that FN1 overexpression is an important determinant of thyroid cancer aggressiveness

Loss of function SETD2 mutations in poorly differentiated metastases from two Hürthle cell carcinomas of the thyroid

Hürthle cell carcinomas (HCC) are rare differentiated thyroid cancers that display low avidity for radioactive iodine and respond poorly to kinase inhibitors. Here, using next-generation sequencing, we analyzed the mutational status of primary tissue and poorly differentiated metastatic tissue from two HCC patients. In both cases, metastatic tissues harbored a mutation of SETD2, each resulting in loss of the SRI and WW domains of SETD2, a methyltransferase that trimethylates H3K36 (H3K36me3) and also interacts with p53 to promote its stability. Functional studies of the novel p.D1890fs6* mutation (case 1) revealed significantly reduced H3K36me3 levels in SETD2-mutated tissue and primary cell cultures and decreased levels of the active form of p53. Restoration of SETD2-wildtype expression in the SETD2-mutant cells significantly reduced the expression of four well-known stemness markers (OCT-4, SOX2, IPF1, Goosecoid). These findings suggest potential roles for SETD2 loss-of-function mutations in HCC progression, possibly involving p53 destabilization and promotion of stemness. Their prevalence and potential treatment implications in thyroid cancer, especially HCC, require further study

RET mutation and increased angiogenesis in medullary thyroid carcinomas

Advanced medullary thyroid cancers (MTCs) are now being treated with drugs that inhibit receptor tyrosine kinases, many of which involved in angiogenesis. Response rates vary widely, and toxic effects are common, so treatment should be reserved for MTCs likely to be responsive to these drugs. RET mutations are common in MTCs, but it is unclear how they influence the microvascularization of these tumors. We examined 45 MTCs with germ-line or somatic RET mutations (RETmut group) and 34 with wild-type RET (RETwt). Taqman Low-Density Arrays were used to assess proangiogenic gene expression. Immunohistochemistry was used to assess intratumoral, peritumoral and nontumoral expression levels of VEGFR1, R2, R3, PDGFRa, PDGFB and NOTCH3. We also assessed microvessel density (MVD) and lymphatic vessel density (LVD) based on CD31-positive and podoplanin-positive vessel counts, respectively, and vascular pericyte density based on staining for a-smooth muscle actin (a-SMA), a pericyte marker. Compared with RETwt tumors, RETmut tumors exhibited upregulated expression of proangiogenic genes (mRNA and protein), especially VEGFR1, PDGFB and NOTCH3. MVDs and LVDs were similar in the two groups. However, microvessels in RETmut tumors were more likely to be a-SMA positive, indicating enhanced coverage by pericytes, which play key roles in vessel sprouting, maturation and stabilization. These data suggest that angiogenesis in RETmut MTCs may be more intense and complete than that found in RETwt tumors, a feature that might increase their susceptibility to antiangiogenic therapy. Given their increased vascular pericyte density, RETmut MTCs might also benefit from combined or preliminary treatment with PDGF inhibitors

Identification of Exosomal microRNAs and Their Targets in Papillary Thyroid Cancer Cells

The release of molecules in exosomal cargoes is involved in tumor development and progression. We compared the profiles of exosomal microRNAs released by two thyroid cancer cell lines (TPC-1 and K1) with that of non-tumorigenic thyroid cells (Nthy-ori-3-1), and we explored the network of miRNA–target interaction. After extraction and characterization of exosomes, expression levels of microRNAs were investigated using custom TaqMan Advanced array cards, and compared with those expressed in the total cell extracts. The functional enrichment and network-based analysis of the miRNAs’ targets was also performed. Five microRNAs (miR-21-5p, miR-31-5p, miR-221-3p, miR-222-3p, and let-7i-3p) were significantly deregulated in the exosomes of tumor cells vs. non-tumorigenic cells, and three of them (miR-31-5p, miR-222-3p, and let-7i-3p) in the more aggressive K1 compared to TPC-1 cells. The network analysis of the five miRNAs identified some genes as targets of more than one miRNAs. These findings permitted the identification of exosomal microRNAs secreted by aggressive PTC cells, and indicated that their main targets are regulators of the tumor microenvironment. A deeper analysis of the functional role of the targets of exosomal miRNAs will provide further information on novel targets of molecular treatments for these neoplasms

A synonymous RET substitution enhances the oncogenic effect of an in-cis missense mutation by increasing constitutive splicing efficiency

Synonymous mutations continue to be filtered out from most large-scale cancer genome studies, but several lines of evidence suggest they can play driver roles in neoplastic disease. We investigated a case of an aggressive, apparently sporadic medullary thyroid carcinoma (MTC) harboring a somatic RET p.Cys634Arg mutation (a known MTC driver). A germ-line RET substitution (p.Cys630=) had also been found but was considered clinically irrelevant because of its synonymous nature. Next generation sequencing (NGS) of the tumor tissues revealed that the RET mutations were in cis. There was no evidence of gene amplification. Expression analysis found an increase of RET transcript in p.Cys630=;p.Cys634Arg patient compared with that found in 7 MTCs harboring p.Cys634 mutations. Minigene expression assays demonstrated that the presence of the synonymous RET mutation was sufficient to explain the increased RET mRNA level. In silico analyses and RNA immunoprecipitation experiments showed that the p.Cys630 = variant created new exonic splicing enhancer motifs that enhanced SRp55 recruitment to the mutant allele, leading to more efficient maturation of its pre-mRNA and an increased abundance of mature mRNA encoding a constitutively active RET receptor. These findings document a novel mechanism by which synonymous mutations can contribute to cancer progression

Contemporary thyroid nodule evaluation and management

Context Approximately 60% of adults harbor one or more thyroid nodules. The possibility of cancer is the overriding concern, but only about 5% prove to be malignant. The widespread use of diagnostic imaging and improved access to healthcare favor the discovery of small, subclinical nodules and small papillary cancers. Overdiagnosis and overtreatment is associated with potentially excessive costs and non-negligible morbidity for patients. Evidence Acquisition We conducted a PubMed search for the recent English-language articles dealing with thyroid nodule management. Evidence Synthesis The initial assessment includes an evaluation of clinical risk factors and sonographic examination of the neck. Sonographic risk-stratification systems (e.g., Thyroid Imaging Reporting and Data Systems [TIRADS]) can be used to estimate the risk of malignancy and the need for biopsy based on nodule features and size. When cytology findings are indeterminate, molecular analysis of the aspirate may obviate the need for diagnostic surgery. Many nodules will not require biopsy. These nodules and those that are cytologically benign can be managed with long-term follow-up alone. If malignancy is suspected, options include surgery (increasingly less extensive), active surveillance or, in selected cases, minimally-invasive techniques. Conclusion Thyroid nodule evaluation is no longer a one-size-fits-all proposition. For most nodules, the likelihood of malignancy can be confidently estimated without resorting to cytology or molecular testing, and low-frequency surveillance is sufficient for most patients. When there are multiple options for diagnosis and/or treatment, they should be discussed with patients as frankly as possible to identify an approach that best meets their needs

Numerical simulation of ambient vibration tests: a case study

The paper introduces a numerical procedure to simulate an ambient excitation of structures. The procedure is applied to a case study of a RC framed building that was studied through a process of structural identification by a dynamic test in situ and a model updating. After this first step the numerical model was used to analyse the response of the structure to different excitations in order to simulate the effect of ambient vibrations and the data collected during a monitoring process; the aim is to reproduce the identification procedure exciting the numerical model. The choice of the signal that can simulate the ambient vibrations used in the experimental dynamic tests is a critical point, therefore the dynamic structural response under different inputs was investigated. The numerical dynamic identification procedure was utilized to highlight the ability of different type of signals to excite only some of the global natural vibration frequencies of the structures, so that the dynamic behaviour of the structure can be obtained by the superposition of the results

Establishment and maintenance of thyroid organoids from human cancer cells

Here, we describe a protocol to generate organoids from human thyroid cancer cells. Starting from the same patient-derived cells, we establish both organoids and primary lines. The organoid medium is supplemented with conditioned medium obtained from the primary cell line. This modification enables culture of the organoid lines for up to 10 months. Even after long-term culture, the organoids retain the genetic and phenotypic characteristics of their tissue of origin