Let-7a down-regulation plays a role in thyroid neoplasias of follicular histotype affecting cell adhesion and migration through its ability to target the FXYD5 (Dysadherin) gene

A pilot study to evaluate the expression of microRNA‑let‑7a in patients with intestinal‑type sinonasal adenocarcinoma

Despite its histological resemblance to colorectal adenocarcinoma, there is little information about the molecular events involved in the pathogenesis of intestinal-type sinonasal adenocarcinoma (ITAC). The present study investigated the possible role and clinical value of microRNA (miR)-let-7a, a head and neck squamous cell carcinoma-related miR, in a well-characterized and homogeneous cohort of patients with ethmoidal ITAC associated with occupational exposure, treated by primary surgery. miR-let-7a expression levels were analyzed in 23 pairs of ethmoidal ITAC and adjacent normal formalin-fixed paraffin-embedded tissues by reverse transcription-quantitative PCR. The expression was evaluated in tumor and healthy tissues according to: Tumor grade (G) of differentiation and extension, and pTNM stage, and presence/absence of recurrence. Comparisons within and between groups were performed using two-tailed Student's paired t-test and one-way ANOVA with Tukey's post hoc test. P<0.05 was considered to indicate a statistically significant difference. miR-let-7a expression in ethmoidal ITAC tissues was significantly lower than that in adjacent normal tissues (P<0.05; mean expression level ± SD, 1.452707±1.4367189 vs. 4.094017±2.7465375). miR expression varied with pT stage. miR-let-7a was downregulated (P<0.05) in advanced stages (pT3-pT4) compared with earlier stages (pT1-pT2). Furthermore, downregulation of miR-let-7a in ITAC was associated with poorly-differentiated (G3) cancer (P<0.05). No other associations were observed between miR-let-7a expression and the other clinicopathological parameters, including disease-free survival. In conclusion, downregulation of miR-let-7a in ITAC was associated with advanced-stage (pT3 and pT4) and poorly-differentiated (G3) disease, suggesting that the mutation of this gene, combined with additional genetic events, could serve a role in ITAC pathogenesis.

Chromatin-Accessible miRNA Regulons Driving Thyroid Tumorigenesis and Progression

BACKGROUND

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Differential Expression of Non-Coding RNA Signatures in Thyroid Cancer between Two Ethnic Groups

Filipino Americans show higher thyroid cancer recurrence rates compared to European Americans. Although they are likely to die of this malignancy, the molecular mechanism has not yet been determined. Recent studies demonstrated that small non-coding RNAs could be utilized to assess thyroid cancer prognosis in tumor models. The goal of this study is to determine whether microRNA (miRNA) signatures are differentially expressed in thyroid cancer in two different ethnic groups. We also determined whether these miRNA signatures are related to cancer staging. This is a retrospective study of archival samples from patients with thyroid cancer (both sexes) in the pathology division from the last ten years at Loma Linda University School of Medicine, California. Deidentified patient demographics were extracted from the patient chart. Discarded formalin-fixed paraffin-embedded tissues were collected post-surgeries. We determined the differential expressions of microRNA in archival samples from Filipino Americans compared to European Americans using the state-of-the-art technique, HiSeq4000. By ingenuity pathway analysis, we determined miRNA targets and the pathways that those targets are involved in. We validated their expressions by real-time quantitative PCR and correlated them with the clinicopathological status in a larger cohort of miRNA samples from both ethnicities. We identified the differentially upregulated/downregulated miRNA clusters in Filipino Americans compared to European Americans. Some of these miRNA clusters are known to target genes that are linked to cancer invasion and metastasis. In univariate analysis, ethnicity and tumor staging were significant factors predicting miR-4633-5p upregulation. When including these factors in a multivariate logistic regression model, ethnicity and tumor staging remained significant independent predictors of miRNA upregulation, whereas the interaction of ethnicity and tumor staging was not significant. In contrast, ethnicity remained an independent predictor of significantly downregulated miR-491-5p and let-7 family. We provide evidence that Filipino Americans showed differentially expressed tumor-tissue-derived microRNA clusters. The functional implications of these miRNAs are under investigation.

Upregulated microRNA let-7a accelerates apoptosis and inhibits proliferation in uterine junctional zone smooth muscle cells in adenomyosis under conditions of a normal activated hippo-YAP1 axis

BACKGROUND

Let-7a is a small non-coding RNA that has been found to take part in cell proliferation and apoptosis. The hippo-YAP1 axis, known as a tumour suppressor pathway, also plays an important role in cell proliferation and apoptosis. YAP1, TAZ, and phospho-YAP1 play key roles in actions of the hippo-YAP1 axis. Adenomyosis (ADS) is a proliferative disease leading to a large uterus in patients with prolonged illness. Abnormal proliferation of smooth muscle cells (SMCs) in the uterine endometrial-myometrial junctional zone (JZ) is an important reason for developing ADS. This study aimed to explore the expression levels of let-7a and components of the hippo-YAP1 axis in SMCs in the uterine endometrial-myometrial JZ in ADS and to explore the roles of let-7a and the hippo-YAP1 axis of JZ SMC proliferation and apoptosis in ADS.

METHODS

We collected JZ tissues for the primary culture of SMCs from 25 women diagnosed with ADS and 27 women without ADS. We used quantitative real-time polymerase chain reaction and western blotting to measure the mRNA and protein expression levels of let-7a, YAP1, TAZ, and phospho-YAP1 in ADS JZ SMCs. A CCK-8 assay and flow cytometry analysis of apoptosis were utilized to test the proliferation and apoptosis of JZ SMCs. The let-7a overexpression lentiviral vector GV280 was used to increase the expression level of let-7a. We added verteporfin to block the phosphorylation of components of the hippo-YAP1 axis.

RESULTS

We found that the let-7a level was decreased, while the YAP1 and TAZ levels were increased in ADS JZ SMCs. Upregulated let-7a affected the expression levels of components of the hippo-YAP1 axis, accelerated apoptosis, and inhibited proliferation in JZ SMCs. Furthermore, accumulated YAP1 led to increasing proliferation of JZ SMCs after verteporfin treatment to block the phosphorylation of components of the hippo-YAP1 axis. If components of the hippo-YAP1 axis were unphosphorylated, upregulated let-7a could not inhibit the proliferation of ADS JZ SMCs. Upregulated let-7a could not activate the hippo-YAP1 axis in verteporfin treatment.

CONCLUSIONS

Our findings suggest that the let-7a and hippo-YAP1 axis may act as important regulators of JZ SMCs proliferation, and upregulated let-7a may be an effective method to treat ADS.

Differential MicroRNA-Signatures in Thyroid Cancer Subtypes

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

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.

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.

Let-7a inhibits migration, invasion and tumor growth by targeting AKT2 in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy. Increasing evidence showed that microRNAs (miRNAs) play an important role in the PTC progression. In our study, the result showed that let-7a is significantly downregulated in PTC tissues and thyroid cancer cell lines. Overexpression of let-7a suppressed PTC cell proliferation, migration and invasion. Interestingly, we found that AKT2 was a direct target of let-7a and the expression levels of AKT2 were also observed to inversely correlate with let-7a expression in PTC tissues. Furthermore, enhancing AKT2 expression partially reversed the inhibitory effects of let-7a in PTC. Taken together, these findings suggest that let-7a acts as a novel suppressor by targeting the AKT2 gene and might be a candidate target for the development of novel therapeutic strategies to treat papillary thyroid carcinoma.

Effects of long non-coding RNA H19 and microRNA let7a expression on thyroid cancer prognosis

This study aims to explore the effects of long non-coding RNA H19 (lncRNA H19) and microRNA let7a (miRNA let7a) expression on the prognosis of thyroid cancer (TC). This may aid in the discovery of more effective treatment and prognosis approaches for TC. Between January 2008 and January 2011, 131 TC tissues and adjacent tissues were obtained from TC patients. An additional 122 normal thyroid tissues were also collected as normal controls from patients with benign thyroid lesions. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect lncRNA H19 and miRNA let7a mRNA expression. Five-year follow-ups were conducted. A Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic values of lncRNA H19 and miRNA let7a in TC. The Kaplan-Meier method was applied to analyze the 5-year survival rate of TC patients. Univariate and multivariate factor analyses were employed to analyze the prognostic factors of TC. The lncRNA H19 mRNA expression was higher while the miRNA let7a mRNA expression was lower in TC tissues than, in the normal thyroid tissues and adjacent tissues. The area under the ROC curve (AUC) of lncRNA H19 and miRNA let7a were 0.801 and 0.116, with sensitivity at 72.5% and 84%, as well as specificity 75.4% and 77%, respectively. In TC patients with tumor diameters≥1.0cm, lncRNA H19 mRNA expression was elevated, but miRNA let7a mRNA expression was reduced. This was also evident in TC patients with TNM stages III+IV and those with lymph node metastasis. TC patients with a lower 5-year survival rate showed upregulated levels of lncRNA H19 expression and, downregulated levels of miRNA let7a expression. LncRNA H19 and miRNA let7a expression, tumor diameter, TNM stage and lymph node metastasis were independent prognostic factors of TC. This study demonstrated that increased lncRNA H19 and decreased miRNA let7a expression levels are associated with poor prognosis in TC patients. An inverse relationship between lncRNA H19 and miRNA let7a expression levels was exhibited.

HMGA1 silencing reduces stemness and temozolomide resistance in glioblastoma stem cells

OBJECTIVE

Glioblastoma multiforme (GBM) develops from a small subpopulation of stem-like cells, which are endowed with the ability to self-renew, proliferate and give rise to progeny of multiple neuroepithelial lineages. These cells are resistant to conventional chemo- and radiotherapy and are hence also responsible for tumor recurrence. HMGA1 overexpression has been shown to correlate with proliferation, invasion, and angiogenesis of GBMs and to affect self-renewal of cancer stem cells from colon cancer. The role of HMGA1 in GBM tumor stem cells is not completely understood.

RESEARCH DESIGN AND METHODS

We have investigated the role of HMGA1 in brain tumor stem cell (BTSC) self-renewal, stemness and resistance to temozolomide by shRNA- mediated HMGA1 silencing.

RESULTS

We first report that HMGA1 is overexpressed in a subset of BTSC lines from human GBMs. Then, we show that HMGA1 knockdown reduces self-renewal, sphere forming efficiency and stemness, and sensitizes BTSCs to temozolomide. Interestingly, HMGA1 silencing also leads to reduced tumor initiation ability in vivo.

CONCLUSIONS

These results demonstrate a pivotal role of HMGA1 in cancer stem cell gliomagenesis and endorse HMGA1 as a suitable target for CSC-specific GBM therapy.

Hypomethylation of let-7a-3 is associated with poor prognosis in myelodysplastic syndrome

Abnormal methylation of let-7a-3 has been found in various cancers and may consequently affect their survival. In this study, real-time quantitative methylation specific PCR (RQ-MSP) was used to determine the unmethylation level of let-7a-3 in 95 patients with myelodysplastic syndrome (MDS). The hypomethylation of let-7a-3 promoter was detected in 22 of 95 (23.2%) patients with MDS compared to 4.2% (1/24) of controls (p= 0.0419). Moreover, the frequency of let-7a-3 hypomethylation was higher in older patients (≥70 years) than in younger patients (<70 years). No significant difference was observed in distribution of WHO, IPSS, and cytogenetic classification. However, hypomethylated patients had significantly shorter overall survival than those without hypomethylation (p= 0.007). Moreover both Kaplan-Meier and Multivariate Cox analyses confirmed that let-7a-3 hypomethylation was an independent prognostic risk factor in cohorts of MDS patients with lower-risk disease. Our study suggested that let-7a-3 hypomethylation may predict poor outcome in MDS.

MicroRNA Expression Profiles in Papillary Thyroid Carcinoma, Benign Thyroid Nodules and Healthy Controls

MicroRNAs (miRNAs) represent a class of short endogenous non-coding RNAs that negatively regulate gene expression at the post-transcriptional level in many biological processes, including proliferation, differentiation, stress response and apoptosis. In this study we analyzed a set of seven miRNA molecules in sera of patients with papillary thyroid cancer, multinodular goiter and healthy controls to identify miRNA molecules that may have utility as markers for PTC. MiR-21 serum levels in the preoperative PTC and MG groups were significantly higher than the control group. Likewise, postoperative levels of miR-151-5p, miR-221 and miR-222 were significantly lower in patients with PTC. When serum miRNA levels were evaluated according to stage, postoperative levels of miR-151-5p and miR-222 were significantly lower in patients with advanced stages of the disease. The miRNA levels were also found associated with the size of the primary tumor. Our data imply that specific miRNA molecules which are differentially expressed in thyroid tumors may play role in the development of papillary thyroid carcinoma.

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

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

FXYD5 is a Marker for Poor Prognosis and a Potential Driver for Metastasis in Ovarian Carcinomas

Ovarian cancer (OC) is a leading cause of cancer mortality, but aside from a few well-studied mutations, very little is known about its underlying causes. As such, we performed survival analysis on ovarian copy number amplifications and gene expression datasets presented by The Cancer Genome Atlas in order to identify potential drivers and markers of aggressive OC. Additionally, two independent datasets from the Gene Expression Omnibus web platform were used to validate the identified markers. Based on our analysis, we identified FXYD5, a glycoprotein known to reduce cell adhesion, as a potential driver of metastasis and a significant predictor of mortality in OC. As a marker of poor outcome, the protein has effective antibodies against it for use in tissue arrays. FXYD5 bridges together a wide variety of cancers, including ovarian, breast cancer stage II, thyroid, colorectal, pancreatic, and head and neck cancers for metastasis studies.

microRNA expression in autonomous thyroid adenomas: Correlation with mRNA regulation

The objective of the study was to identify the deregulated miRNA in autonomous adenoma and to correlate the data with mRNA regulation. Seven autonomous adenoma with adjacent healthy thyroid tissues were investigated. Twelve miRNAs were downregulated and one was upregulated in the tumors. Combining bioinformatic mRNA target prediction and microarray data on mRNA regulations allowed to identify mRNA targets of our deregulated miRNAs. A large enrichment in mRNA encoding proteins involved in extracellular matrix organization and different phosphodiesterases were identified among these putative targets. The direct interaction between miR-101-3p and miR-144-3p and PDE4D mRNA was experimentally validated. The global miRNA profiles were not greatly modified, confirming the definition of these tumors as minimal deviation tumors. These results support a role for miRNA in the regulation of extracellular matrix proteins and tissue remodeling occurring during tumor development, and in the important negative feedback of the cAMP pathway, which limits the consequences of its constitutive activation in these tumors.

miR-142-3p down-regulation contributes to thyroid follicular tumorigenesis by targeting ASH1L and MLL1

CONTEXT

A previous micro-RNA expression profile of thyroid follicular adenomas identified miR-142 precursor among the miRNAs downregulated in the neoplastic tissues compared to normal thyroid gland.

OBJECTIVE

The aim of this work has been to assess the expression of miR-142-3p in a large panel of follicular thyroid adenomas and carcinomas and evaluate its effect on thyroid cell proliferation and target expression.

DESIGN

The expression of miR-142-3p was analyzed by qRT-PCR in thyroid follicular adenomas and carcinomas, compared to normal thyroids. MiR-142-3p expression was restored in WRO cells and the effects on cell proliferation and target expression were evaluated.

RESULTS

Here we show that miR-142-3p is downregulated in FTAs, FTCs, and FVPTCs. MiR-142-3p was demonstrated to reduce the proliferation rate of WRO and FTC133 cells, supporting its tumor suppressor role in thyroid cancerogenesis. Moreover, this microRNA was able to downregulate the expression of ASH1L and MLL1, by direct and indirect mechanisms, respectively. Consistently, an inverse correlation between miR-142-3p expression and ASH1L and MLL1 proteins was found in thyroid follicular adenomas and carcinomas. ASH1L and MLL1, which belong to the Trithorax group (TrxG) proteins and are major regulators of Homeobox gene expression, maintain active target gene transcription by histone 3 lysine 4 methylation. Interestingly, we found that FTCs and FTC cell lines express tumor specific, shorter forms of the two proteins. The capability of miR-142-3p to modulate the levels of these tumor-associated forms and to reactivate thyroid-specific Hox gene expression, likely contributes to its tumor suppressive function.

CONCLUSIONS

These data demonstrate that miR-142-3p downregulation has a role in thyroid tumorigenesis, by regulating ASH1L and MLL1.

Cancer stem-like cells and thyroid cancer

Thyroid cancer is one of the most rapidly increasing malignancies. The reasons for this increase is not completely known, but increases in the diagnosis of papillary thyroid microcarcinomas and follicular variant of papillary thyroid carcinomas along with the enhanced detection of well-differentiated thyroid carcinomas are probably all contributing factors. Although most cases of well-differentiated thyroid carcinomas are associated with an excellent prognosis, a small percentage of patients with well-differentiated thyroid carcinomas as well as most patients with poorly differentiated and anaplastic thyroid carcinomas have recurrent and/or metastatic disease that is often fatal. The cancer stem-like cell (CSC) model suggests that a small number of cells within a cancer, known as CSCs, are responsible for resistance to chemotherapy and radiation therapy, as well as for recurrent and metastatic disease. This review discusses current studies about thyroid CSCs, the processes of epithelial-to-mesenchymal transition (EMT), and mesenchymal-to-epithelial transition that provide plasticity to CSC growth, in addition to the role of microRNAs in CSC development and regulation. Understanding the biology of CSCs, EMT and the metastatic cascade should lead to the design of more rational targeted therapies for highly aggressive and fatal thyroid cancers.

Expression profiling of exosomal miRNAs derived from human esophageal cancer cells by Solexa high-throughput sequencing

Cellular genetic materials, such as microRNAs (miRNAs), mRNAs and proteins, are packaged inside exosomes, small membrane vesicles of endocytic origin that are released into the extracellular environment. These cellular genetic materials can be delivered into recipient cells, where they exert their respective biological effects. However, the miRNA profiles and biological functions of exosomes secreted by cancer cells remain unknown. The present study explored the miRNA expression profile and distribution characteristics of exosomes derived from human esophageal cancer cells through Solexa high-throughput sequencing. Results showed that 56,421 (2.94%) unique sequences in cells and 7727 (0.63%) in exosomes matched known miRNAs. A total of 342 and 48 known miRNAs were identified in cells and exosomes, respectively. Moreover, 64 and 32 novel miRNAs were predicted in cells and exosomes, respectively. Significant differences in miRNA expression profiles were found between human esophageal cancer cells and exosomes. These findings provided new insights into the characteristics of miRNAs in exosomes derived from human esophageal cancer cells and the specific roles of miRNAs in intercellular communication mediated by exosomes in esophageal cancer.

MicroRNA Deregulation in Anaplastic Thyroid Cancer Biology

Anaplastic thyroid cancer (ATC) is among the most lethal types of cancers, characterized as a fast-growing and highly invasive thyroid tumor that is unresponsive to surgery and radioiodine, blunting therapeutic efficacy. Classically, genetic alterations in tumor suppressor TP53 are frequent, and cumulative alterations in different signaling pathways, such as MAPK and PI3K, are detected in ATC. Recently, deregulation in microRNAs (miRNAs), a class of small endogenous RNAs that regulate protein expression, has been implicated in tumorigenesis and cancer progression. Deregulation of miRNA expression is detected in thyroid cancer. Upregulation of miRNAs, such as miR-146b, miR-221, and miR-222, is observed in ATC and also in differentiated thyroid cancer (papillary and follicular), indicating that these miRNAs' overexpression is essential in maintaining tumorigenesis. However, specific miRNAs are downregulated in ATC, such as those of the miR-200 and miR-30 families, which are important negative regulators of cell migration, invasion, and epithelial-to-mesenchymal transition (EMT), processes that are overactivated in ATC. Therefore, molecular interference to restore the expression of tumor suppressor miRNAs, or to blunt overexpressed oncogenic miRNAs, is a promising therapeutic approach to ameliorate the treatment of ATC. In this review, we will explore the importance of miRNA deregulation for ATC cell biology.

Differential miRNA expression defines migration and reduced apoptosis in follicular thyroid carcinomas

The objective of the study was to identify microRNAs (miRs) characteristic for follicular thyroid carcinoma (FTC) and to define their role in tumorigenesis. A miR-microarray study was conducted to identify miRs differentially expressed between FTCs and their surrounding tissues. Selection was further reinforced by a literature review. Four miRs were selected and confirmed by RT-qPCR: miR-146b, -183, -221 were up-regulated, whereas miR-199b down-regulated in FTCs. The influence of these miRs on cell proliferation, cell cycle, apoptosis and migration was studied in HTori and FTC-133 cells. Functional characterization suggests an impact of miR-183 and miR-146b in FTC development. Overexpression of both miRs significantly induces migration. Moreover, overexpression of miR-183 significantly represses apoptosis. MiR-199b and -221 do not have significant effects on proliferation, cell cycle, apoptosis or migration in HTori and FTC-133 cells. Our data suggest that miR-146b and miR-183 may influence FTC development through the induction of migration and apoptosis inhibition.

Noncoding RNAs in endocrine malignancy

Only recently has it been uncovered that the mammalian transcriptome includes a large number of noncoding RNAs (ncRNAs) that play a variety of important regulatory roles in gene expression and other biological processes. Among numerous kinds of ncRNAs, short noncoding RNAs, such as microRNAs, have been extensively investigated with regard to their biogenesis, function, and importance in carcinogenesis. Long noncoding RNAs (lncRNAs) have only recently been implicated in playing a key regulatory role in cancer biology. The deregulation of ncRNAs has been demonstrated to have important roles in the regulation and progression of cancer development. In this review, we describe the roles of both short noncoding RNAs (including microRNAs, small nuclear RNAs, and piwi-interacting RNAs) and lncRNAs in carcinogenesis and outline the possible underlying genetic mechanisms, with particular emphasis on clinical applications. The focus of our review includes studies from the literature on ncRNAs in traditional endocrine-related cancers, including thyroid, parathyroid, adrenal gland, and gastrointestinal neuroendocrine malignancies. The current and potential future applications of ncRNAs in clinical cancer research is also discussed, with emphasis on diagnosis and future treatment.

Deregulation of microRNA expression in thyroid neoplasias

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

The miRNA let-7a1 inhibits the expression of insulin-like growth factor 1 receptor (IGF1R) in prostate cancer PC-3 cells

Reduced microRNA (miRNA) let-7a expression and the activation of insulin-like growth factor-1 receptor (IGF1R) signalling are both involved in prostate cancer and progression. In the present study, we demonstrated that the growth inhibitory effect of let-7a1 is directly related to targeting IGF1R gene expression in PC-3 cells. TargetScan predicted three potential target sites (T1, T2 and T3) of let-7a in the 3' untranslational region (3' UTR) of IGF1R mRNA. Real-time PCR, Western blot and luciferase reporter assays were used to detect the effects of let-7a1 overexpression or let-7a1 inhibitor on the IGF1R gene expression in PC-3 cells. The results indicated that let-7a1 could inhibit IGF1R expression by directly targeting the T1 and T2 sites in the 3' UTR of the IGF1R mRNA. We then used RT-PCR, luciferase reporter assays, 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyl-2H-tetrazolium bromide (MTT) assay, flow cytometry and Hoechst 33342 staining to examine whether let-7a1-mediated inhibition of IGF1R expression also affects the IGF1R-mediated signalling events, including Elk1 activity and c-fos gene expression, proliferation, apoptosis and cell cycle. We demonstrated that let-7a1-mediated IGF1R downregulation was accompanied by attenuation of Elk1 activity and c-fos expression, inhibition of cell proliferation, enhanced apoptosis and cell cycle arrest, and that loss function of let-7a1 via inhibition can upregulate IGF1R accompanied by an increase of Elk1 activity and c-fos expression, thereby enhancing cell proliferation. Altogether, these findings suggest that let-7a may be novel therapeutic candidate for prostate cancer.