MicroRNA deregulation in human thyroid papillary carcinomas

Selection and validation of miRNAs as normalizers for profiling expression of microRNAs isolated from thyroid fine needle aspiration smears

Fine needle aspiration cytology (FNAC) is currently the method of choice for malignancy prediction in thyroid nodules. Nevertheless, in some cases the interpretation of FNAC results may be problematic due to limitations of the method. The expression level of some microRNAs changes with the development of thyroid tumors, and its quantitation can be used to refine the FNAC results. For this quantitation to be reliable, the obtained data must be adequately normalized. Currently, no reference genes are universally recognized for quantitative assessments of microRNAs in thyroid nodules. The aim of the present study was the selection and validation of such reference genes. Expression of 800 microRNAs in 5 paired samples of thyroid surgical material corresponding to different histotypes of tumors was analyzed using NanoString technology and four of these (hsa-miR-151a-3p, -197-3p, -99a-5p and -214-3p) with the relatively low variation coefficient were selected. The possibility of use of the selected microRNAs and their combination as references was estimated by RT-qPCR on a sampling of cytological smears: benign (n=226), atypia of undetermined significance (n=9), suspicious for follicular neoplasm (n=61), suspicious for malignancy (n=19), medullary thyroid carcinoma (MTC) (n=32), papillary thyroid carcinoma (PTC) (n=54) and non-diagnostic material (ND) (n=34). In order to assess the expression stability of the references, geNorm algorithm was used. The maximum stability was observed for the normalization factor obtained by the combination of all 4 microRNAs. Further validation of the complex normalizer and individual selected microRNAs was performed using 5 different classification methods on 3 groups of FNAC smears from the analyzed batch: benign neoplasms, MTC and PTC. In all cases, the use of the complex classifier resulted in the reduced number of errors. On using the complex microRNA normalizer, the decision-tree method C4.5 makes it possible to distinguish between malignant and benign thyroid neoplasms in cytological smears with high overall accuracy (>91%).

Overexpression of long non-coding RNA NR_036575.1 contributes to the proliferation and migration of papillary thyroid cancer

Current evidence suggests that the human genome produces a large number of non-coding RNAs, including microRNAs and long non-coding RNAs (lncRNAs). Generally, lncRNAs are defined as RNA transcripts longer than 200 nucleotides that are not transcribed into proteins. In recent years, lncRNAs have been reported to play oncogenic roles in tumourigenesis. However, minimal research has been performed on the expression and clinicopathological significance of lncRNAs in papillary thyroid cancer (PTC). In the present study, we investigated not only the expression and clinicopathological significance of a novel lncRNA, NR_036575.1, in PTC tissues and adjacent non-cancerous tissues but also its potential function in TPC1 cells. The expression levels of the lncRNA NR_036575.1 in 83 pairs of PTC tissues and adjacent non-cancerous tissues were detected via quantitative real-time polymerase chain reaction. The relationships between the expression levels and clinicopathological characteristics of the lncRNA NR_036575.1 were analysed. In addition, we established two receiver operating characteristic (ROC) curves to assess the diagnostic value of NR_036575.1 expression. Cell Counting Kit-8 and transwell assays were used to assess cell proliferation and migration, respectively. The expression levels of the lncRNA NR_036575.1 were significantly higher in PTC tissues than in adjacent non-cancerous tissues. High NR_036575.1 expression was associated with extrathyroidal extension (ETE) (P = 0.011) and tumour size (P = 0.006). The ROC curves indicated that NR_036575.1 could potentially serve as a biomarker for identifying PTC and related, non-cancerous diseases (sensitivity, 80.7 %; specificity, 88 %), as well as for differentiating between PTC with or without ETE (sensitivity, 57.8 %; specificity, 86.7 %). NR_036575.1 knock-down significantly inhibited the proliferation and migration of TPC1 cells. Our findings are the first to describe lncRNA NR_036575.1 overexpression in PTC. NR_036575.1 expression was associated with both ETE and tumour size. In addition, NR_036575.1 modulation could regulate TPC1 cell proliferation and migration. The results of our study suggest that NR_036575.1 could be applied as a potential biomarker and a novel therapeutic target for PTC patients.

Integrated miRNA profiling and bioinformatics analyses reveal potential causative miRNAs in gastric adenocarcinoma

Gastric cancer (GC) is one of the leading causes of cancer-related deaths throughout China and worldwide. The discovery of microRNAs (miRNAs) has provided a new opportunity for developing diagnostic biomarkers and effective therapeutic targets in GC. By performing microarray analyses of benign and malignant gastric epithelial cell lines (HFE145, NCI-N87, MKN28, RF1, KATO III and RF48), 16 significantly dysregulated miRNAs were found. 11 of these were validated by real-time qRT-PCR. Based on miRWalk online database scans, 703 potential mRNA targets of the 16 miRNAs were identified. Bioinformatic analyses suggested that these dysregulated miRNAs and their predicted targets were principally involved in tumor pathogenesis, MAPK signaling, and apoptosis. Finally, miRNA-gene network analyses identified miRNA-125b as a crucial miRNA in GC development. Taken together, these results develop a comprehensive expression and functional profile of differentially expressed miRNAs related to gastric oncogenesis. This profile may serve as a potential tool for biomarker and therapeutic target identification in GC patients.

Cancer stem cells as a potential therapeutic target in thyroid carcinoma

A number of studies have indicated that tumor growth and proliferation is dependent on a small subset of cells, defined as cancer stem cells (CSCs). CSCs have the capability to self-renew, and are involved with cancer propagation, relapse and metastatic dissemination. CSCs have been isolated from numerous tissues, including normal and cancerous thyroid tissue. A regulatory network of signaling pathways and microRNAs (miRNAs) control the properties of CSCs. Differentiated thyroid carcinoma is the most common type of endocrine cancer, with an increasing incidence. Anaplastic thyroid carcinoma is the most rare type of endocrine cancer; however, it also exhibits the highest mortality rate among thyroid malignancies, with an extremely short survival time. Thyroid CSCs are invasive and highly resistant to conventional therapies, including radiotherapy and chemotherapy, which results in disease relapse even when the primary lesion has been eradicated. Therefore, targeting thyroid CSCs may represent an effective treatment strategy against aggressive neoplasms, including recurrent and radioresistant tumors. The present review summarizes the current literature regarding thyroid CSCs and discusses therapeutic strategies that target these cells, with a focus on the function of self-renewal pathways and miRNAs. Elucidation of the mechanisms that regulate CSC growth and survival may improve novel therapeutic approaches for treatment-resistant thyroid cancers.

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.

microRNA-7 regulates cell growth, migration and invasion via direct targeting of PAK1 in thyroid cancer

The expression and function of microRNA-7 (miR-7) has been studied in a variety of different cancer types. However, to date, no studies have investigated the expression of miR‑7 in human thyroid cancer. In the present study, the expression levels and biological function of miR‑7 were investigated in human thyroid cancer, with the aim of evaluating whether it may serve as a therapeutic biomarker. The expression levels of miR‑7 in human thyroid cancer tissues, matched, adjacent normal tissues, normal thyroid tissues and human thyroid cancer cell lines were determined using RT‑qPCR and western blot analysis. To explore the functional role of miR‑7 in human thyroid cancer cell lines, MTT assays, cell migration and invasion assays were employed. TargetScan software identified p21 activated kinase‑1 (PAK1) as a putative interacting partner of miR‑7. Therefore, functional assays were performed to explore the effects of endogenous PAK1 in thyroid cancer. In the present study, miR‑7 was significantly downregulated in thyroid cancer tissues and cells compared with normal thyroid tissue samples. A correlation between miR‑7 expression and thyroid tumor stage was also observed. Ectopic expression of miR‑7 was found to suppress the proliferation, migra-tion and invasion of thyroid cancer cells in vitro. Dual-luciferase reporter assays demonstrated that PAK1 was a direct target of miR-7 in vitro. RT-qPCR and western blot analysis demonstrated that miR‑7 negatively regulates PAK1 protein expression but has no effect on PAK1 mRNA expression. Knockdown of PAK1 expression markedly suppressed thyroid cancer cell proliferation, migration and invasion. These results suggest that miR‑7 functions as a tumor suppressor by targeting PAK1 directly and may therefore present a novel therapeutic target for the treatment of thyroid cancer.

Intermediate microRNA expression profile in Graves’ disease falls between that of normal thyroid tissue and papillary thyroid carcinoma

Aims

Many studies have previously reported a higher prevalence of papillary thyroid carcinomas (PTC) in patients with Graves' disease (GD). MicroRNAs (miRNAs) are small, non-coding RNAs that are upregulated in PTC compared with benign thyroid tissue. The objective of the study was to examine the miRNA expression of selected miRNAs that are known to be upregulated in PTC in patients with GD.

Methods

Paraffin embedded thyroid tissue from 159 patients with GD was screened for expression of the miRNAs 146b, 181b, 21, 221 and 222 by RT-PCR. The expression profiles of four normal thyroids, 50 PTCs without concomitant GD and 11 patients with untreated GD served as the controls.

Results

The expression pattern of these miRNAs in patients with GD is intermediate between that of benign thyroid tissue (p<0.001) and PTC (in three out of five miRNAs, p<0.001). This corresponds to a 15-fold change for GD versus PTC, and a 31-fold change for GD versus normal thyroid tissue. The miRNA expression in 11 papillary microcarcinomas found in our study (a prevalence of 0.07) was not different from that in PTC samples from patients without GD for four of five miRNA types. Furthermore, we found a significant difference in the expression of miRNA 221/222 between treated and untreated GD tissue.

Conclusions

In conclusion, we found an intermediate expression of specific miRNAs in thyroid tissue from patients with GD that fell between the expression levels found in normal thyroid glands and PTC, which suggests a possible influence of certain miRNAs on developing PTC in patients with GD.

Altered expression of mir-222 and mir-25 influences diverse gene expression changes in transformed normal and anaplastic thyroid cells, and impacts on MEK and TRAIL protein expression

Thyroid cancer is the most common endocrine malignancy and accounts for the majority of endocrine cancer-related deaths each year. Our group and others have previously demonstrated dysfunctional microRNA (miRNA or miR) expression in the context of thyroid cancer. The objective of the present study was to investigate the impact of synthetic manipulation of expression of miR-25 and miR-222 in benign and malignant thyroid cells. miR-25 and miR-222 expression was upregulated in 8505C (an anaplastic thyroid cell line) and Nthy-ori (a SV40-immortalised thyroid cell line) cells, respectively. A transcriptomics-based approach was utilised to identify targets of the two miRNAs and real-time PCR and western blotting were used to validate a subset of the targets. Almost 100 mRNAs of diverse functions were found to be either directly or indirectly targeted by both miR-222 and miR-25 [fold change ≥2, false discovery rate (FDR) ≤0.05]. Gene ontology analysis showed the miR-25 gene target list to be significantly enriched for genes involved in cell adhesion. Fluidigm real-time PCR technologies were used to validate the downregulation of 23 and 22 genes in response to miR-25 and miR-222 overexpression, respectively. The reduction of the expression of two miR-25 protein targets, TNF-related apoptosis-inducing ligand (TRAIL) and mitogen-activated protein kinase kinase 4 (MEK4), was also validated. Manipulating the expression of both miR-222 and miR-25 influenced diverse gene expression changes in thyroid cells. Increased expression of miR-25 reduced MEK4 and TRAIL protein expression, and cell adhesion and apoptosis are important aspects of miR-25 functioning in thyroid cells.

The Role of miRNA in Papillary Thyroid Cancer in the Context of miRNA Let-7 Family

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy. RET/PTC rearrangement is the most common genetic modification identified in this category of cancer, increasing proliferation and dedifferentiation by the activation of the RET/PTC-RAS-BRAF-MAPK-ERK signaling pathway. Recently, let-7 miRNA was found to reduce RAS levels, acting as a tumor suppressor gene. Circulating miRNA profiles of the let-7 family may be used as novel noninvasive diagnostic, prognostic, treatment and surveillance markers for PTC.

Ursolic acid induced anti-proliferation effects in rat primary vascular smooth muscle cells is associated with inhibition of microRNA-21 and subsequent PTEN/PI3K

This study focused on the anti-proliferation effects of ursolic acid (UA) in rat primary vascular smooth muscle cells (VSMCs) and investigated underlying molecular mechanism of action. Rat primary VSMCs were pretreated with UA (10, 20 or 30μM) or amino guanidine (AG, 50μM) for 12h or with PI3K inhibitor LY294002 for 30min or with Akt inhibitor MK2206 for 24h, then 10% fetal bovine serum was used to induce proliferation. CCK-8 was used to assess cell proliferation. To explore the mechanism, cells were treated with UA (10, 20 or 30μM), LY294002 or MK2206, or transient transfected to inhibit miRNA-21 (miRNA-21) or to overexpress PTEN, then quantitative real-time PCR was used to assess the mRNA levels of miRNA-21 and phosphatase and tensin homolog (PTEN) for cells treated with UA or miRNA-21 inhibitor; western blotting was used to measure the protein levels of PTEN and PI3K. UA exerted significant anti-proliferation effects in rat primary VSMCs. Furthermore, UA inhibited the expression of miRNA-21 and subsequently enhanced the expression of PTEN. PTEN was found to inhibit the expression of PI3K. In conclusion, UA exerts anti-proliferation effects in rat primary VSMCs, which is associated with the inhibition of miRNA-21 expression and modulation of PTEN/PI3K signaling pathway.

Integrated microRNA, gene expression and transcription factors signature in papillary thyroid cancer with lymph node metastasis

Background. Papillary thyroid carcinoma (PTC) is the commonest thyroid malignancy originating from the follicle cells in the thyroid. Despite a good overall prognosis, certain high-risk cases as in those with lymph node metastasis (LNM) have progressive disease and poorer prognosis. MicroRNAs are a class of non-protein-coding, 19–24 nucleotides single-stranded RNAs which regulate gene expression and these molecules have been shown to play a role in LNM. The integrated analysis of miRNAs and gene expression profiles together with transcription factors (TFs) has been shown to improve the identification of functional miRNA-target gene-TF relationships, providing a more complete view of molecular events underlying metastasis process.

Objectives. We reanalyzed The Cancer Genome Atlas (TCGA) datasets on PTC to identify differentially expressed miRNAs/genes in PTC patients with LNM-positive (LNM-P) versus lymph node negative (LNN) PTC patients and to investigate the miRNA-gene-TF regulatory circuit that regulate LNM in PTC.

Results. PTC patients with LNM (PTC LNM-P) have a significantly shorter disease-free survival rate compared to PTC patients without LNM (PTC LNN) (Log-rank Mantel Cox test, p = 0.0049). We identified 181 significantly differentially expressed miRNAs in PTC LNM-P versus PTC LNN; 110 were upregulated and 71 were downregulated. The five topmost deregulated miRNAs were hsa-miR-146b, hsa-miR-375, hsa-miR-31, hsa-miR-7-2 and hsa-miR-204. In addition, 395 miRNAs were differentially expressed between PTC LNM-P and normal thyroid while 400 miRNAs were differentially expressed between PTC LNN and normal thyroid. We found four significant enrichment pathways potentially involved in metastasis to the lymph nodes, namely oxidative phosphorylation (OxPhos), cell adhesion molecules (CAMs), leukocyte transendothelial migration and cytokine–cytokine receptor interaction. OxPhos was the most significantly perturbed pathway (p = 4.70E−06) involving downregulation of 90 OxPhos-related genes. Significant interaction of hsa-miR-301b with HLF, HIF and REL/NFkB transcription factors were identified exclusively in PTC LNM-P versus PTC LNN.

Conclusion. We found evidence of five miRNAs differentially expressed in PTC LNM-P. Alteration in OxPhos pathway could be the central event in metastasis to the lymph node in PTC. We postulate that hsa-miR-301b might be involved in regulating LNM in PTC via interactions with HLF, HIF and REL/NFkB. To the best of our knowledge, the roles of these TFs have been studied in PTC but the precise role of this miRNA with these TFs in LNM in PTC has not been investigated.

Analytical validity of a microRNA-based assay for diagnosing indeterminate thyroid FNA smears from routinely prepared cytology slides

BACKGROUND

The majority of thyroid nodules are diagnosed using fine‐needle aspiration (FNA) biopsies. The authors recently described the clinical validation of a molecular microRNA‐based assay, RosettaGX Reveal, which can diagnose thyroid nodules as benign or suspicious using a single stained FNA smear. This paper describes the analytical validation of the assay.

METHODS

More than 800 FNA slides were tested, including slides stained with Romanowsky‐type and Papanicolaou stains. The assay was examined for the following features: intranodule concordance, effect of stain type, minimal acceptable RNA amounts, performance on low numbers of thyroid cells, effect of time since sampling, and analytical sensitivity, specificity, and reproducibility.

RESULTS

The assay can be run on FNA slides for which as little as 1% of the cells are thyroid epithelial cells or from which only 5 ng of RNA have been extracted. Samples composed entirely of blood failed quality control and were not classified. Stain type did not affect performance. All slides were stored at room temperature. However, the length of time between FNA sampling and processing did not affect assay performance. There was a high level of concordance between laboratories (96%), and the concordance for slides created from the same FNA pass was 93%.

CONCLUSIONS

The microRNA‐based assay was robust to various physical processing conditions and to differing sample characteristics. Given the assay's performance, robustness, and use of routinely prepared FNA slides, it has the potential to provide valuable aid for physicians in the diagnosis of thyroid nodules. Cancer Cytopathol 2016;124:711–21. © 2016 Rosetta Genomics. Cancer Cytopathology published by Wiley Periodicals, Inc. on behalf of American Cancer Society.

Analytical validation of a novel molecular assay for the diagnosis of thyroid nodules with indeterminate cytology using stained fine‐needle aspiration smears is described. The results demonstrate the assay's robustness to various physical processing conditions.

Reciprocal activation between STAT3 and miR-181b regulates the proliferation of esophageal cancer stem-like cells via the CYLD pathway

Background

Recent studies have suggested that cancer cells contain subpopulations that can initiate tumor growth, self-renew, and maintain tumor cell growth. However, for esophageal cancer cells, the relationship between STAT3, microRNAs and cancer stem cells remains unclear.

Methods

Serum-free culture was used to enrich esophageal cancer stem-like cells (ECSLC). Flow cytometry determined the proportion of ECSLC. qPCR were performed to examine expression level of stemness factors, mesenchymal markers, ATP-binding cassette (ABC) transporters, STAT3, miR-181b, CYLD. Western blot were performed to analyze the expression of STAT3, p-STAT3 and CYLD (cylindromatosis). BALB/c mice xenograft studies were conducted to evaluate the tumorigenicity of enriched ECSLC. Sphere formation assay and colony formation assays were employed to analyze the relationship between STAT3 and miR-181b. Luciferase assays were used to evaluate activity which CYLD is a target of miR-181b.

Results

Sphere formation cells (SFCs) with properties of ECSLC were enriched. Enriched SFCs in serum-free suspension culture exhibited cancer stem-like cell properties and increased single-positive CD44 + CD24-, stemness factor, mesenchymal marker expression ABC transporters and tumorigenicity in vivo compared with the parental cells. Additionally, we found that reciprocal activation between STAT3 and miR-181b regulated SFCs proliferation. Moreover, STAT3 directly activated miR-181b transcription in SFCs and miR-181b then potentiated p-STAT3 activity. Luciferase assays indicated that CYLD was a direct and functional target of miR-181b.

Conclusion

The mutual regulation between STAT3 and miR-181b in SFCs was required for proliferation and apoptosis resistance. STAT3 and miR-181b control each other’s expression in a positive feedback loop that regulates SFCs via CYLD pathway. These findings maybe is helpful for targeting ECSLC and providing approach for esophageal cancer treatments.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0521-7) contains supplementary material, which is available to authorized users.

Slug-upregulated miR-221 promotes breast cancer progression through suppressing E-cadherin expression

It is generally regarded that E-cadherin is downregulated during tumorigenesis via Snail/Slug-mediated E-cadherin transcriptional reduction. However, this transcriptional suppressive mechanism cannot explain the failure of producing E-cadherin protein in metastatic breast cancer cells after overexpressing E-cadherin mRNA. Here we reveal a novel mechanism that E-cadherin is post-transcriptionally regulated by Slug-promoted miR-221, which serves as an additional blocker for E-cadherin expression in metastatic tumor cells. Profiling the predicted E-cadherin-targeting miRNAs in breast cancer tissues and cells showed that miR-221 was abundantly expressed in breast tumor and metastatic MDA-MB-231 cells and its level was significantly higher in breast tumor or MDA-MB-231 cells than in distal non-tumor tissue and low-metastatic MCF-7 cells, respectively. MiR-221, which level inversely correlated with E-cadherin level in breast cancer cells, targeted E-cadherin mRNA open reading frame (ORF) and suppressed E-cadherin protein expression. Depleting or increasing miR-221 level in breast cancer cells induced or decreased E-cadherin protein level, leading to suppressing or promoting tumor cell progression, respectively. Moreover, miR-221 was specifically upregulated by Slug but not Snail. TGF-β treatment enhanced Slug activity and thus increased miR-221 level in MCF-7 cells. In summary, our results provide the first evidence that Slug-upregulated miR-221 promotes breast cancer progression via reducing E-cadherin expression.

Value of distinguishing differentiated thyroid carcinoma by miRNA

Current methods for diagnosing thyroid carcinoma are time consuming or expensive. Thus, alternative approaches are required. In the present study, microRNAs (miRNAs) with higher sensitivity and specificity were screened while distinguishing between differentiated thyroid carcinoma (DTC) and subtype papillary thyroid carcinoma (PTC). A total of 120 cases suspected of having thyroid carcinoma were selected and examined using clinical color Doppler ultrasound, and computed tomography scan at the same time. The tissue specimens were obtained with fine needle aspiration, multiphase biopsy and surgical resection. The expression of miR146b, miR221 and miR222 was detected uisng the RT-quantitative polymerase chain reaction method. The receiver operating characteristic curve was used to obtain the cut-off value. Pathological examination identified 8 cases of normal thyroid tissue; 9 cases of hyperplastic nodules; 12 cases of thyroid adenoma; and 91 cases of thyroid carcinoma, of which 59 cases were DTC, 15 cases were follicular carcinoma and 17 cases were undifferentiated carcinoma. In the thyroid carcinoma, the expression levels of miR146b, miR221 and miR222 were significantly higher than those of other tissues (P<0.05). The expression levels of these miRNAs in the differentiated type were also significantly higher than those in the undifferentiated type (P<0.05). A comparison of the differentiated subunit identified no statistically significant difference (P>0.05). Following diagnosis of DTC, the area under curve (AUC) of miR146b, miR221 and miR222 was 0.832, 0.806 and 0.745, respectively; the cut-off values were 1.346, 1.213 and 1.425, respectively; susceptibility was 72.8, 71.5 and 68.7%, respectively; and specificity was 62.3, 60.9 and 59.3%, respectively. The AUC of the combined miR-146b and -221 following diagnosis of PTC was 0.695; the cut-off values were 1.506 and 1.462, respectively; susceptibility was 78.9%; and specificity was 68.5%. The AUC of the combined miR-146b and -222 was 0.677; the cut-off values were 1.523 and 1.443, respectively; susceptibility was 76.3%; and specificity was 66.4%. The AUC of the combined miR-221 and -222 was 0.662; the cut-off values were 1.564 and 1.437, respectively; susceptibility was 74.9%; and specificity was 68.2%. In conclusion, miR146b, miR221 and miR222 may be used as susceptibility and specificity indices of DTC, although they cannot be used as susceptibility or specificity indices for distinguishing PTC. Combining the two indices together can improve diagnostic accuracy to a certain extent.

PATZ1 is a target of miR-29b that is induced by Ha-Ras oncogene in rat thyroid cells

The regulatory transcriptional factor PATZ1 is constantly downregulated in human thyroid cancer where it acts as a tumour suppressor by targeting p53-dependent genes involved in Epithelial-Mesenchymal Transition and cell migration. The aim of the present work was to elucidate the upstream signalling mechanisms regulating PATZ1 expression in thyroid cancer cells. The bioinformatics search for microRNAs able to potentially target PATZ1 led to the identification of several miRNAs. Among them we focused on the miR-29b since it was found upregulated in rat thyroid differentiated cells transformed by the Ha-Ras oncogene towards a high proliferating and high migratory phenotype resembling that of anaplastic carcinomas. Functional assays confirmed PATZ1 as a target of miR-29b, and, consistently, an inverse correlation between miR-29b and PATZ1 protein levels was found upon induction of Ha-Ras oncogene expression in these cells. Interestingly, restoration of PATZ1 expression in rat thyroid cells stably expressing the Ha-Ras oncogene decreased cell proliferation and migration, indicating a key role of PATZ1 in Ras-driven thyroid transformation. Together, these results suggest a novel mechanism regulating PATZ1 expression based on the upregulation of miR-29b expression induced by Ras oncogene.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

MiRNA-146b-5p upregulates migration and invasion of different Papillary Thyroid Carcinoma cells

Background

Tumor invasiveness is directly related to the ability of tumor cells to migrate and invade surrounding tissues, usually degrading extracellular matrix. Despite significant progress in the knowledge about migration and invasion, there is much more to elucidate about their regulatory mechanisms, especially in cancer cells. MicroRNAs (miRs) were recently described as important regulators of migration. Differential expression of miRs in cancer is frequently associated with progression, invasion and metastasis. In papillary thyroid carcinoma (PTC), miR-146b-5p is highly expressed and positively correlated to the degree of malignancy.

Methods

This study aimed to investigate the role of miR-146b-5p on the migratory and invasive behaviors of thyroid cells, using a non tumor rat thyroid follicular cell line (PCCl3) transfected with the miR-146b-5p genomic region, and two PTC cell lines (TPC-1 and BCPAP, bearing distinct oncogenic backgrounds), which express high levels of miR-146b-5p, after miR-146b inhibition by antagomiR and miR-146b overexpression by mimics-miR. Migration and invasion were studied by time-lapse and transwell assays (with and without Matrigel®). Gelatin degradation assays were also employed, as well as F-actin staining.

Results

Migration and invasion of PCCl3 were increased 2-3x after miR-146b-5p overexpression (10X) and large lamellipodia were evident in those cells. After miR-146b-5p inhibition, TPC-1 and BCPAP migration and invasion were significantly reduced, with cells showing several simultaneous processes and low polarity. Gelatin degradation was inhibited in TPC-1 cells after inhibition of miR-146b-5p, but was unaffected in BCPAP cells, which did not degrade gelatin. The inhibition of miR-146b-5p in PCCl3 also inhibited migration and invasion, and additional (exogenous) overexpression of this miR in TPC-1 and BCPAP cells increased migration and invasion, without effects on cell morphology or gelatin degradation. The overexpression of SMAD4 in BCPAP cells, a validated target of miR-146b-5p and key protein in the TGF-β signaling pathway, inhibited migration similarly to the effects observed with the antagomiR 146b-5p.

Conclusions

miR-146b-5p positively regulates migration and invasion of thyroid normal and tumor follicular cells (independently from their original mutation, either BRAF or RET/PTC), through a mechanism that involves the actin cytoskeleton but not an increased capacity of matrix degradation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2146-z) contains supplementary material, which is available to authorized users.

MiR-221 promotes stemness of breast cancer cells by targeting DNMT3b

Cancer stem cells (CSCs) are a small part of the heterogeneous tumor cell population possessing self-renewal and multilineage differentiation potential as well as a great ability to sustain tumorigenesis. The molecular pathways underlying CSC phenotype are not yet well characterized. MicroRNAs (miRs) are small noncoding RNAs that play a powerful role in biological processes. Early studies have linked miRs to the control of self-renewal and differentiation in normal and cancer stem cells. We aimed to study the functional role of miRs in human breast cancer stem cells (BCSCs), also named mammospheres. We found that miR-221 was upregulated in BCSCs compared to their differentiated counterpart. Similarly, mammospheres from T47D cells had an increased level of miR-221 compared to differentiated cells. Transfection of miR-221 in T47D cells increased the number of mammospheres and the expression of stem cell markers. Among miR-221's targets, we identified DNMT3b. Furthermore, in BCSCs we found that DNMT3b repressed the expression of various stemness genes, such as Nanog and Oct 3/4, acting on the methylation of their promoters, partially reverting the effect of miR-221 on stemness. We hypothesize that miR-221 contributes to breast cancer tumorigenicity by regulating stemness, at least in part through the control of DNMT3b expression.

Molecular cytopathology for thyroid nodules: A review of methodology and test performance

Advances in the molecular characterization of thyroid cancers have fueled the development of genetic and gene expression-based tests for thyroid fine-needle aspirations. Collectively, these tests are designed to improve the diagnostic certainty of thyroid cytology. This review summarizes the early published experience with the commercially available versions of these tests: the Afirma Gene Expression Classifier, ThyGenX (formerly miRInform)/ThyraMIR, and ThyroSeq. Key differences in testing approaches and issues regarding test performance and interpretation are also discussed.

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.

Schizophrenia-Associated MIR204 Regulates Noncoding RNAs and Affects Neurotransmitter and Ion Channel Gene Sets

As regulators of gene expression, microRNAs (miRNAs) are likely to play an important role in the development of disease. In this study we present a large-scale strategy to identify miRNAs with a role in the regulation of neuronal processes. Thereby we found variant rs7861254 located near the MIR204 gene to be significantly associated with schizophrenia. This variant resulted in reduced expression of miR-204 in neuronal-like SH-SY5Y cells. Analysis of the consequences of the altered miR-204 expression on the transcriptome of these cells uncovered a new mode of action for miR-204, being the regulation of noncoding RNAs (ncRNAs), including several miRNAs, such as MIR296. Furthermore, pathway analysis showed downstream effects of miR-204 on neurotransmitter and ion channel related gene sets, potentially mediated by miRNAs regulated through miR-204.

Over-expression of microRNA-375 inhibits papillary thyroid carcinoma cell proliferation and induces cell apoptosis by targeting ERBB2

MicroRNAs (miRs) played important roles in the cell proliferation, apoptosis and other biological processes in cancer. In the present study we found that miR-375 was significantly down-regulated in human papillary thyroid carcinoma (PTC) tissues and cell lines. In this study we try to investigate the biological activity of miR-375 in human PTC cells and try to find the potential target of miR-375. Our study indicated that over-expression of miR-375 could inhibit the PTC cells proliferation and this inhibition was caused by the induction of cell apoptosis. In vivo animal study indicated that over-expression of miR-375 could significantly decrease the migration and invasion of human PTC cell in vivo. These results exhibit over-expression of miR-375 in human PTC cells could inhibit the process of human PTC. Further study demonstrated ERBB2 was a direct target of miR-375, over-expression of miR-375 decrease the both mRNA and protein expression of ERBB2 in human PTC cells. These data indicate miR-375 play important roles in the process and development of human PTC. These finds suggested that appropriate application of miR-375 regulation might be a new sight for the treatment of human PTC in the future.

Follicular cell-derived thyroid cancer

Follicular cell-derived thyroid cancers are derived from the follicular cells in the thyroid gland, which secrete the iodine-containing thyroid hormones. Follicular cell-derived thyroid cancers can be classified into papillary thyroid cancer (80-85%), follicular thyroid cancer (10-15%), poorly differentiated thyroid cancer (<2%) and undifferentiated (anaplastic) thyroid cancer (<2%), and these have an excellent prognosis with the exception of undifferentiated thyroid cancer. The advent and expansion of advanced diagnostic techniques has driven and continues to drive the epidemic of occult papillary thyroid cancer, owing to overdiagnosis of clinically irrelevant nodules. This transformation of the thyroid cancer landscape at molecular and clinical levels calls for the modification of management strategies towards personalized medicine based on individual risk assessment to deliver the most effective but least aggressive treatment. In thyroid cancer surgery, for instance, injuries to structures outside the thyroid gland, such as the recurrent laryngeal nerve in 2-5% of surgeries or the parathyroid glands in 5-10% of surgeries, negatively affect quality of life more than loss of the expendable thyroid gland. Furthermore, the risks associated with radioiodine ablation may outweigh the risks of persistent or recurrent disease and disease-specific mortality. Improvement in the health-related quality of life of survivors of follicular cell-derived thyroid cancer, which is decreased despite the generally favourable outcome, hinges on early tumour detection and minimization of treatment-related sequelae. Future opportunities include more widespread adoption of molecular and clinical risk stratification and identification of actionable targets for individualized therapies.

MiR-181b regulates cisplatin chemosensitivity and metastasis by targeting TGFβR1/Smad signaling pathway in NSCLC

MicroRNAs (miRNAs) have been identified as important post-transcriptional regulators involved in various biological and pathological processes of cells, but their underlying mechanisms in chemosensitivity and metastasis have not been fully elucidated. The objective of this study was to identify miR-181b and its mechanism in the chemosensitivity and metastasis of NSCLC. We found that miR-181b expression levels were lower in A549/DDP cells compared with A549 cells. Functional assays showed that the overexpression of miR-181b inhibited proliferation, enhanced chemosensitivity to DDP, attenuated migration and metastatic ability in NSCLC cell lines in vitro and in vivo. TGFβR1 was subsequently identified as a novel functional target of miR-181b. TGFβR1 knockdown revealed similar effects as that of ectopic miR-181b expression, whereas overexpression of TGFβR1 rescued the function of miR-181b-mediated growth, chemosensitivity and metastasis in NSCLC cells. In addition, miR-181b could inactivate the TGFβR1/Smad signaling pathway. We also observed that decreased miR-181b expression and increased TGFβR1 expression were significantly associated with chemosensitivity to DDP and tumor metastasis in NSCLC patients. Consequently, miR-181b functions as a tumor suppressor and has an important role in proliferation, chemosensitivity to DDP and metastasis of NSCLC by targeting TGFβR1/Smad signaling pathway.

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.

MiR-125b promotes cell migration and invasion by targeting PPP1CA-Rb signal pathways in gastric cancer, resulting in a poor prognosis

BACKGROUND

MiR-125b functions as an oncogene in many cancers; however, its clinical significance and molecular mechanism in gastric cancers have never been sufficiently investigated. Here, we elucidated the functions and molecular regulated pathways of MiR-125b in gastric cancer.

METHODS

We investigated MiR-125b expression in fresh tissues from 50 gastric cancer patients and 6 gastric cancer cell lines using RT-PCR, and explored its prognostic value by hybridizing MiR-125b in situ for 300 clinical gastric tumor tissues with pathological diagnosis and clinical parameters. The effects of MiR-125b on gastric cancer cells and downstream target genes and proteins were analyzed by MTT, transwell assay, RT-PCR, and western blot on the basis of silencing MiR-125b in vitro. Luciferase reporter plasmid was constructed to demonstrate MiR-125b's direct target.

RESULTS

MiR-125b was upregulated in gastric cancer tissues and cell lines, and significantly promoted cellular proliferation, migration, and invasion by downregulating the expression of PPP1CA and upregulating Rb phosphorylation. MiR-125b expression was significantly correlated with tumor size and depth of invasion, lymph nodes, distant metastasis, and TNM stage. The high-MiR-125b-expression group had a significantly poorer prognosis than the low-expression group (P < 0.05) in stages I, II, and III, and the 5-year survival rate in of the high-expression group was significantly lower than that of the low-expression group.

CONCLUSIONS

MiR-125b functions as an oncogene by targeting downregulated PPP1CA and upregulated Rb phosphorylation in gastric cancer. MiR-125b not only promotes cellular proliferation, migration, and invasion in vitro, but also acts as an independent prognostic factor in gastric cancer.

Association Between Genetic Polymorphisms in the Promoter Regions of Let-7 and Risk of Papillary Thyroid Carcinoma: A Case-Control Study

The aim of this study was to investigate the association between 2 polymorphisms (ie, rs10877887 and rs13293512) in the promoter regions of let-7 and the risk of papillary thyroid carcinoma (PTC).A case-control study of 618 PTC patients and 562 controls was conducted. The rs10877887 polymorphism was genotyped by using polymerase chain reaction-restriction fragment length polymorphism and the rs13293512 polymorphism was genotyped by using a TaqMan Genotyping Assay. The results were confirmed by DNA sequencing.The rs10877887 polymorphism had reduced risks of PTC in heterozygous comparison, dominant model, and overdominant model (TC vs TT: adjusted odds ratio [OR] = 0.73, 95% confidence interval [95% CI] = 0.58-0.94, P = 0.01; TC/CC vs TT: adjusted OR = 0.79, 95% CI = 0.63-1.00, P = 0.047; TC vs TT/CC: adjusted OR = 0.73, 95% CI = 0.57-0.92, P = 0.007, respectively). Stratified analyses showed that PTC patients carrying the rs10877887 CC genotype were more likely to have multiple tumors (adjusted OR = 1.71, 95% CI = 1.03-2.86, P = 0.04), and PTC patients carrying the rs13293512 TC + CC or CC were more likely to develop N0 status (TC/CC vs TT: adjusted OR = 0.64, 95% CI = 0.43-0.94, P = 0.02; CC vs

TC/TT

adjusted OR = 0.50, 95% CI = 0.33-0.77, P = 0.001, respectively).Our study suggests that the rs10877887 polymorphism may be associated with the risk of PTC and the rs13293512 polymorphism may correlate to lymph node metastasis in PTC.

Upregulation of miR-1280 expression in non-small cell lung cancer tissues

Background:

Non-small cell lung cancer (NSCLC) is a prolific and high-mortality disease with few effective treatments. Although the detection and surgical techniques for NSCLC continue to advance, the survival rate for the patients with NSCLC remains poor. Enhanced predictive biomarkers such as microRNAs (miRNAs) are needed at the time of diagnosis to better tailor therapies for patients. This study focused on the expression of miR-1280 in NSCLC tissues and distal normal tissues in order to explore the association between miR-1280 expression and NSCLC.

Methods:

A total of 72 newly diagnosed primary NSCLC patients were enrolled in this study. Quantitative real-time polymerase chain reaction (PCR) was performed to identify the expression level of miR-1280 in the NSCLC tissues and distal normal tissues of these patients.

Results:

The miR-1280 expression was significantly higher in the NSCLC tissues (0.084 ± 0.099) than distal normal tissues (0.014 ± 0.015, P = 0.009). In 54 patients (75%), the miR-1280 expression in the NSCLC tissues was upregulated (2^−ΔΔct > 2), and no case showed a downregulation of miR-1280 expression.

Conclusions:

The expression level of miR-1280 could be regarded as a biomarker for NSCLC.

Serum microRNA profiling to distinguish papillary thyroid cancer from benign thyroid masses

Objectives

Papillary thyroid cancer (PTC) is increasing in incidence. Fine needle aspiration is the gold standard for diagnosis, but results can be indeterminate. Identifying tissue and serum biomarkers, like microRNA, is therefore desirable. We sought to identify miRNA that is differentially expressed in the serum of patients with PTC.

Methods

Serum miRNA was quantified in 31 female thyroidectomy patients: 13 with benign disease and 18 with PTC. qPCR results were compared for significant fold-changes in 175 miRNAs, against a pooled control.

Results

128 miRNA qualified for analysis. There were identifiable fold-changes in miRNA levels between benign and control, and between PTC and control. There were statistically significant fold changes in the level of four miRNAs between benign and PTC: hsa-miR-146a-5p and hsa-miR-199b-3p were down-regulated, while hsa-let7b-5p and hsa-miR-10a-5p were up-regulated.

Conclusions

MicroRNA is differentially expressed in the serum of patients with PTC. Serum miRNA has the potential to aid in thyroid cancer diagnosis.

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.

Prognostic and biological significance of microRNA-221 in breast cancer

INTRODUCTION

Breast cancer (BC) is the most notorious cancer between females with high rates of morbidity and mortality. The aim of this study was to determine the differential expression of breast tissues microRNA-221 (miR-221) and assess its prognostic and biological significance in breast cancer (BC).

METHODS

A quantitative reverse transcription PCR (qPCR) assay was performed to detect the expression of breast tissue miR-221 in different subtypes of BC (n=76) and controls (n=36) and its correlations with clinicopathological factors of patients. Univariate and multivariate analyses using the Cox proportional hazards model were performed to analyze the prognostic significance of miR-221 expression.

RESULT

Our data indicated that the relative level of miR-221 expression in BC tissues was significantly higher than that in noncancerous breast tissues (p<0.01). Of 76 BC patients, 62 (81.6%) were positive cases. By statistical analyses, high miR-221 expression was observed to be closely correlated with advanced clinical stage (p<0.01). Moreover, patients with high miR-221 expression had worse 5-year relapse free survival (p=0.0124). Univariate and multivariate analyses indicated that high miR-221 expression was an independent poor prognostic factor for BC patients.

CONCLUSION

miR-221 is a potential biomarker for predicting the survival of BC patients and may be a molecular therapeutic target for BC.

Circulating miR-25-3p and miR-451a May Be Potential Biomarkers for the Diagnosis of Papillary Thyroid Carcinoma

OBJECTIVE

There is no effective and reliable biomarker to distinguish benign thyroid nodules from papillary thyroid carcinomas (PTC). This study aimed at examining the levels of plasma miRNAs in patients with PTC or benign nodules to explore the potential miRNA biomarkers for PTC.

PATIENTS AND METHODS

Genome-wide plasma miRNA expression profiles were determined by the miRNA Microarray and the significantly higher levels of miRNAs were validated in plasma and tissues by quantitative RT-PCR. The levels of two miRNAs were further tested in seven patients before and after tumor excision and the potential values for the diagnosis of PTC were evaluated by receiver operating characteristic curve (ROC).

RESULTS

In comparison with that in the patients with benign nodules, eight significantly higher and three lower levels of plasma miRNAs were detected in the PTC patients. Further validation indicated that the levels of plasma miR-25-3p, miR-451a, miR-140-3p and let-7i were significantly higher in the PTC cases than in those with benign nodules or the healthy controls. Significantly higher levels of miR-25-3p and miR-451a were detected in the thyroid tissues from the PTC patients. The levels of plasma miR-25-3p and miR-451a in seven patients significantly decreased after tumor excision. ROC analyses revealed that the levels of plasma miR-25-3p at cut-off 1.41 and miR-451a at 1.38 had sensitivity of 92.8% and 88.9%, and specificity of 68.8% and 66.7% for distinguishing PTC from benign nodules, respectively.

CONCLUSION

Our findings suggest that the levels of plasma miR-25-3p and miR-451a may be valuable for the diagnosis of PTC.

Epstein-Barr Virus Proteins EBNA3A and EBNA3C Together Induce Expression of the Oncogenic MicroRNA Cluster miR-221/miR-222 and Ablate Expression of Its Target p57KIP2

We show that two host-encoded primary RNAs (pri-miRs) and the corresponding microRNA (miR) clusters--widely reported to have cell transformation-associated activity--are regulated by EBNA3A and EBNA3C. Utilising a variety of EBV-transformed lymphoblastoid cell lines (LCLs) carrying knockout-, revertant- or conditional-EBV recombinants, it was possible to demonstrate unambiguously that EBNA3A and EBNA3C are both required for transactivation of the oncogenic miR-221/miR-222 cluster that is expressed at high levels in multiple human tumours--including lymphoma/leukemia. ChIP, ChIP-seq, and chromosome conformation capture analyses indicate that this activation results from direct targeting of both EBV proteins to chromatin at the miR-221/miR-222 genomic locus and activation via a long-range interaction between enhancer elements and the transcription start site of a long non-coding pri-miR located 28 kb upstream of the miR sequences. Reduced levels of miR-221/miR-222 produced by inactivation or deletion of EBNA3A or EBNA3C resulted in increased expression of the cyclin-dependent kinase inhibitor p57KIP2, a well-established target of miR-221/miR-222. MiR blocking experiments confirmed that miR-221/miR-222 target p57KIP2 expression in LCLs. In contrast, EBNA3A and EBNA3C are necessary to silence the tumour suppressor cluster miR-143/miR-145, but here ChIP-seq suggests that repression is probably indirect. This miR cluster is frequently down-regulated or deleted in human cancer, however, the targets in B cells are unknown. Together these data indicate that EBNA3A and EBNA3C contribute to B cell transformation by inhibiting multiple tumour suppressor proteins, not only by direct repression of protein-encoding genes, but also by the manipulation of host long non-coding pri-miRs and miRs.

Expression Levels of miR-30a-5p in Papillary Thyroid Carcinoma: A Comparison Between Serum and Fine Needle Aspiration Biopsy Samples

BACKGROUND

Fine needle aspiration biopsy (FNAB) is a useful tool in the diagnosis of thyroid nodules. However, some limitations exist as approximately 25% of the cases cannot be distinguished with this method. Therefore, identification of novel diagnostic markers is very important in improving the papillary thyroid carcinoma (PTC) diagnosis. microRNAs (miRNAs) are small regulatory RNA molecules that have been involved in a variety of biological processes, including tumorigenesis. Moreover, determination of miRNAs with prognostic, diagnostic, and therapeutic potential is of a great interest today.

AIMS

In the present study, we evaluated the expression level of miR-30a-5p in serum and FNAB samples of PTC patients.

METHODS

A total of 60 cases were included in the study, with the patients subdivided into four groups; benign, atypical cells of undetermined significance (ACUS), malignant group, including Hurthle cell PTC (HC-PTC), and malignant without Hurthle cell PTC (non-HC-PTC). Peripheral blood and FNAB samples of the cases were collected. The serum and FNAB expression levels of miR-30a-5p among the groups were compared. The miR-30a-5p expression level was determined using real-time polymerase chain reaction (RT-PCR).

RESULTS

According to both pre- and postoperative pathological diagnosis, miR-30a-5p levels were significantly increased in both serum and FNAB samples of HC-PTC and non-HC-PTC groups compared to other groups. This increase was more evident in the non-HC-PTC group (p=0.0245 for FNAB, p=0.0166 for serum).

CONCLUSIONS

The results of this study suggest that miR-30a-5p might be a novel diagnostic marker candidate in PTC. Further studies are required to investigate this possibility.

MicroRNA deep-sequencing reveals master regulators of follicular and papillary thyroid tumors

MicroRNA deregulation could be a crucial event in thyroid carcinogenesis. However, current knowledge is based on studies that have used inherently biased methods. Thus, we aimed to define in an unbiased way a list of deregulated microRNAs in well-differentiated thyroid cancer in order to identify diagnostic and prognostic markers. We performed a microRNA deep-sequencing study using the largest well-differentiated thyroid tumor collection reported to date, comprising 127 molecularly characterized tumors with follicular or papillary patterns of growth and available clinical follow-up data, and 17 normal tissue samples. Furthermore, we integrated microRNA and gene expression data for the same tumors to propose targets for the novel molecules identified. Two main microRNA expression profiles were identified: one common for follicular-pattern tumors, and a second for papillary tumors. Follicular tumors showed a notable overexpression of several members of miR-515 family, and downregulation of the novel microRNA miR-1247. Among papillary tumors, top upregulated microRNAs were miR-146b and the miR-221~222 cluster, while miR-1179 was downregulated. BRAF-positive samples displayed extreme downregulation of miR-7 and -204. The identification of the predicted targets for the novel molecules gave insights into the proliferative potential of the transformed follicular cell. Finally, by integrating clinical follow-up information with microRNA expression, we propose a prediction model for disease relapse based on expression of two miRNAs (miR-192 and let-7a) and several other clinicopathological features. This comprehensive study complements the existing knowledge about deregulated microRNAs in the development of well-differentiated thyroid cancer and identifies novel markers associated with recurrence-free survival.

MiR-9 and miR-21 as prognostic biomarkers for recurrence in papillary thyroid cancer

Despite low mortality rates, nodal recurrence in papillary thyroid carcinoma occurs in up to 20 % of patients. Emerging evidences indicate that dysregulated microRNAs are implicated in the process of metastasis. In the present study, we investigated whether miR-9, miR-10b, miR-21 and miR-146b levels are predictive of papillary thyroid carcinoma recurrence. Using macro-dissection followed by quantitative real-time PCR, we measured miR-9, miR-10b, miR-21 and miR-146b expression levels in formalin-fixed, paraffin-embedded samples of 66 patients with papillary thyroid carcinoma categorized into two groups: the recurrent group (n = 19) and the non-recurrent group (n = 47). All patients underwent total thyroidectomy and were followed for at least 120 months after surgery to be considered recurrence-free. Univariate and multivariate analysis were performed using the Cox proportional hazard model in order to identify associations between multiple clinical variables and microRNA expression levels and papillary thyroid carcinoma recurrence. MiR-9 and miR-21 expression levels were found to be significant prognostic factors for recurrence in patients with papillary thyroid carcinoma (HR = 1.48; 95 % CI 1.24-1.77, p < 0.001; and HR = 1.52; 95 % CI 1.18-1.94, p = 0.001; respectively). Multivariate analysis involving the expression level of miR-9 and miR-21 and various clinical parameters identified the expression of these microRNAs as independent prognostic factors for papillary thyroid cancer patients. In conclusion, our results support the potential clinical value of miR-9 and miR-21 as prognostic biomarkers for recurrence in papillary thyroid carcinoma.

MicroRNAs as potential signatures of environmental exposure or effect: a systematic review

BACKGROUND

The exposome encompasses all life-course environmental exposures from the prenatal period onward that influence health. MicroRNAs (miRNAs) are interesting entities within this concept as markers and causation of disease. MicroRNAs are short oligonucleotide sequences that can interact with several mRNA targets.

OBJECTIVES

We reviewed the current state of the field on the potential of using miRNAs as biomarkers for environmental exposure. We investigated miRNA signatures in response to all types of environmental exposure to which a human can be exposed, including cigarette smoke, air pollution, nanoparticles, and diverse chemicals; and we examined the health conditions for which the identified miRNAs have been reported (i.e., cardiovascular disease, cancer, and diabetes).

METHODS

We searched the PubMed and ScienceDirect databases to identify relevant studies.

RESULTS

For all exposures incorporated in this review, 27 miRNAs were differentially expressed in at least two independent studies. miRNAs that had expression alterations associated with smoking observed in multiple studies are miR-21, miR-34b, miR-125b, miR-146a, miR-223, and miR-340; and those miRNAs that were observed in multiple air pollution studies are miR-9, miR-10b, miR-21, miR-128, miR-143, miR-155, miR-222, miR-223, and miR-338. We found little overlap among in vitro, in vivo, and human studies between miRNAs and exposure. Here, we report on disease associations for those miRNAs identified in multiple studies on exposure.

CONCLUSIONS

miRNA changes may be sensitive indicators of the effects of acute and chronic environmental exposure. Therefore, miRNAs are valuable novel biomarkers for exposure. Further studies should elucidate the role of the mediation effect of miRNA between exposures and effect through all stages of life to provide a more accurate assessment of the consequences of miRNA changes.

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.

miR-219-5p modulates cell growth of papillary thyroid carcinoma by targeting estrogen receptor α

CONTEXT

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy. It has been demonstrated that micro-RNAs (miRNAs) are involved in the development of PTC. The miRNA-chromatin immunoprecipitation microarray assay revealed down-regulation of miR-219-5p; however, the effect of miR-219-5p on PTC cell growth remains unknown. This result implied the critical role of miR-219-5p in the development of PTC.

METHODS

We investigated the association between miR-219-5p and PTC development. Expression of miR-219-5p was monitored in 30 PTC tissue specimens and compared with that in 30 normal thyroid tissue specimens. The effect of miR-219-5p on PTC development was studied by cell proliferation, migration, and apoptosis assays. The underlying mechanism was clarified by a reporter assay and rescue experiment.

RESULTS

The current study confirmed that miR-219-5p expression was inhibited in PTC tissue samples. There were statistically significant differences in the expression of miR-219-5p with regard to sex, tumor size, and lymph node metastasis in patients with PTC. Forced expression of miR-219-5p suppressed PTC cell proliferation and migration and promoted apoptosis. Further study showed that estrogen receptor (ER) α was the direct target of miR-219-5p and mediated the effect of miR-219-5p on PTC occurrence. Expression of miR-219-5p was inversely correlated with that of ERα. Importantly, ERα overexpression in PTC cells rescued the inhibitory effect of miR-219-5p on PTC cell proliferation and migration. Thus, our results indicated that miR-219-5p played a critical role in PTC growth by inhibiting ERα.

CONCLUSION

Our investigation identified miR-219-5p as a negative regulator of PTC development through targeting of ERα.

microRNA-339-5p modulates Na+/I- symporter-mediated radioiodide uptake

Na(+)/I(-) symporter (NIS)-mediated radioiodide uptake (RAIU) serves as the basis for targeted ablation of thyroid cancer remnants. However, many patients with thyroid cancer have reduced NIS expression/function and hence do not benefit from radioiodine therapy. microRNA (miR) has emerged as a promising therapeutic target in many diseases; yet, the role of miRs in NIS-mediated RAIU has not been investigated. In silico analysis was used to identify miRs that may bind to the 3'UTR of human NIS (hNIS). The top candidate miR-339-5p directly bound to the 3'UTR of hNIS. miR-339-5p overexpression decreased NIS-mediated RAIU in HEK293 cells expressing exogenous hNIS, decreased the levels of NIS mRNA, and RAIU in transretinoic acid/hydrocortisone (tRA/H)-treated MCF-7 human breast cancer cells as well as thyrotropin-stimulated PCCl3 rat thyroid cells. Nanostring nCounter rat miR expression assay was conducted to identify miRs deregulated by TGFβ, Akti-1/2, or 17-AAG known to modulate RAIU in PCCl3 cells. Among 38 miRs identified, 18 were conserved in humans. One of the 18 miRs, miR-195, was predicted to bind to the 3'UTR of hNIS and its overexpression decreased RAIU in tRA/H-treated MCF-7 cells. miR-339-5p was modestly increased in most papillary thyroid carcinomas (PTCs), yet miR-195 was significantly decreased in PTCs. Interestingly, the expression profiles of 18 miRs could be used to distinguish most PTCs from nonmalignant thyroid tissues. This is the first report, to our knowledge, demonstrating that hNIS-mediated RAIU can be modulated by miRs, and that the same miRs may also play roles in the development or maintenance of thyroid malignancy. Accordingly, miRs may serve as emerging targets to halt the progression of thyroid cancer and to enhance the efficacy of radioiodine therapy.

Differential Expression of MicroRNAs in Papillary Thyroid Carcinoma and Their Role in Racial Disparity

Objective

MicroRNAs (miRNAs) are known to play important roles in the diagnosis and prognosis of papillary thyroid cancer (PTC), and they are useful in developing targeted therapies. However, there have been no studies on the existence of racial differences in miRNAs expression that could explain differential overall survival of PTC patients. Expression analysis of miRNAs in major racial groups would be important for optimizing personalized treatment strategies. In the current study, we assessed the differential expression of 8 miRNAs between normal and tumor tissues, and also assessed racial differences between African American (AA) and Caucasian American (CA).

Methods

First, the miRNA expression profiling was performed using formalin-fixed paraffin embedded (FFPE) tissue sections of tumor containing over 70% tumor cells. Normal and tumor sections of thyroid tissues were studied from AA and CA patients. The miRNA microarray profiling was done using miRBase version 18 (LC Sciences, Houston, TX, USA). Quantitative real-time PCR (qRT-PCR) was used to validate expression of 8 selected miRNAs.

Results

Ingenuity pathway analysis showed involvement of target genes, such as Ras and NF-κB. Deregulated miRNAs such as miR-221 and miR-31 were found to be statistically significant between the two races. Using qRT-PCR, we found that miR-21, miR-146b, miR-221, miR-222, miR-31, and miR-3613 were up-regulated while miR-138 and miR-98 were down-regulated in tumors compared to normal tissues.

Conclusion

Though sample size was small, we found several deregulated miRNAs having racial differences. The differential expression of miRNAs suggest that these miRNAs and their target genes could be useful to gain further mechanistic insight of PTC and their clinical implications, including miRNA replacement therapy or their knockdown strategies.