The roles of the epithelial-mesenchymal transition marker PRRX1 and miR-146b-5p in papillary thyroid carcinoma progression

miRNA expression and function in thyroid carcinomas: a comparative and critical analysis and a model for other cancers

As in many cancer types, miRNA expression profiles and functions have become an important field of research on non-medullary thyroid carcinomas, the most common endocrine cancers. This could lead to the establishment of new diagnostic tests and new cancer therapies. However, different studies showed important variations in their research strategies and results. In addition, the action of miRNAs is poorly considered as a whole because of the use of underlying dogmatic truncated concepts. These lead to discrepancies and limits rarely considered. Recently, this field has been enlarged by new miRNA functional and expression studies. Moreover, studies using next generation sequencing give a new view of general miRNA differential expression profiles of papillary thyroid carcinoma. We analyzed in detail this literature from both physiological and differential expression points of view. Based on explicit examples, we reviewed the progresses but also the discrepancies and limits trying to provide a critical approach of where this literature may lead. We also provide recommendations for future studies. The conclusions of this systematic analysis could be extended to other cancer types.

Hobnail Variant of Papillary Thyroid Carcinoma: a Literature Review

Papillary thyroid carcinoma is the most common thyroid malignancy and it is usually associated with a good prognosis. However, recurrence, metastases, and cancer death may occur in 10 to 15% of patients with more aggressive types of papillary thyroid carcinoma, such as tall cell, columnar cell, solid variant, or the more recently described hobnail variant of papillary thyroid carcinoma. Papillary thyroid carcinoma with a prominent hobnail pattern is a moderately differentiated papillary thyroid carcinoma variant with aggressive clinical behavior and significant mortality. The hobnail variant of papillary thyroid carcinoma shows prominent hobnail features, which have also been referred to as micropapillary. The typical hobnail/micropapillary morphological features show loss of cellular polarity/cohesiveness and support an epithelial-mesenchymal transition as a possible mechanism of metastasis. BRAF p.V600E is the most common mutation in papillary thyroid carcinoma, including the hobnail variant; recent and continuing studies are focused on defining other molecular anomalies that may be useful for prognostic stratification and may provide therapeutic targets.

AKT activity is elevated in aggressive thyroid neoplasms where it promotes proliferation and invasion

The PI3K/AKT/mTOR signaling pathway controls major cellular processes such as cell growth, proliferation and survival. Stimulation of this pathway leads to AKT phosphorylation and activation, resulting in phosphorylation of mTOR and myriad other targets. AKT upregulation has been implicated in thyroid cancer pathogenesis and is a candidate treatment target for patients with advanced disease that has not responded to traditional therapies. Here we evaluate a large series of benign and malignant thyroid tumors for AKT activity and intracellular distribution. We also deplete AKT from multiple thyroid cancer cell lines, including putative cancer stem cell lines, and measure the effect on proliferation and invasion in vitro. We show that active AKT has a predominantly nuclear distribution and its expression is highest in anaplastic thyroid carcinomas and papillary thyroid carcinomas, including encapsulated and invasive follicular variants. Depletion of AKT in thyroid carcinoma cell lines led to greatly reduced proliferative capacity and resulted in a reduction of invasive potential. A reduction in invasion was also observed in the cancer stem cell compartment. Targeting AKT activity in the clinical setting may slow the growth and spread of aggressive thyroid neoplasms, and target the tumor stem cell compartment.

Pathological processes and therapeutic advances in radioiodide refractory thyroid cancer

While in most patients with non-medullary thyroid cancer (TC), disease remission is achieved by thyroidectomy and ablation of tumor remnants by radioactive iodide (RAI), a substantial subgroup of patients with metastatic disease present tumor lesions that have acquired RAI resistance as a result of dedifferentiation. Although oncogenic mutations in BRAF, TERT promoter and TP53 are associated with an increased propensity for induction of dedifferentiation, the role of genetic and epigenetic aberrations and their effects on important intracellular signaling pathways is not yet fully elucidated. Also immune, metabolic, stemness and microRNA pathways have emerged as important determinants of TC dedifferentiation and RAI resistance. These signaling pathways have major clinical implications since their targeting could inhibit TC progression and could enable redifferentiation to restore RAI sensitivity. In this review, we discuss the current insights into the pathological processes conferring dedifferentiation and RAI resistance in TC and elaborate on novel advances in diagnostics and therapy to improve the clinical outcome of RAI-refractory TC patients.

Downregulated expression of TSHR is associated with distant metastasis in thyroid cancer

In differentiated thyroid cancer (DTC), the association between thyroid-stimulating hormone receptor (TSHR) and metastasis, and the underlying molecular mechanisms remain unclear. The role of TSHR in the epithelial-mesenchymal transition (EMT) has not yet been reported, to the best of our knowledge. In the present study, the role of TSHR in the distant metastasis of DTC was investigated. TSHR was significantly downregulated in well-differentiated thyroid cancer cells and tissues, and a lack of TSHR promoted thyroid cancer cell invasion and metastasis by inhibiting the EMT of thyroid cancer cells. In addition, the prognostic value of TSHR in thyroid cancer was analyzed. Immunohistochemical analysis of 172 DTC tissues revealed that a lack of expression of TSHR was associated with distant metastasis and a poor survival rate. Multivariate analyses demonstrated that TSHR expression was a significant prognostic factor for distant metastasis and survival time. The results from the present study demonstrated that TSHR inhibits metastasis through regulating EMT in vitro, and that a lack of expression of TSHR is a significant independent factor affecting distant metastasis and poor prognosis in DTC.

The evolving concept of cancer stem-like cells in thyroid cancer and other solid tumors

The cancer stem-like cell (CSC) hypothesis postulates that a small population of cells in a cancer has self-renewal and clonal tumor initiation properties. These cells are responsible for tumor initiation, growth, recurrence and for resistance to chemotherapy and radiation therapy. CSCs can be characterized using markers such as SSEA-1, SSEA-4, CD44, CD24, ALDEFLUOR and others. CSCs form spheres when they are cultured in serum-free condition in low attachment plates and can generate tumors when injected into immune-deficient mice. During epithelial to mesenchymal transition (EMT), cells lose cellular adhesion and polarity and acquire an invasive phenotype. Recent studies have established a relationship between EMT and increased numbers of CSCs in some solid malignancies. Non-coding RNAs such as microRNAs and long non-coding RNAs (lncRNAs) have been shown to have important roles during EMT and some of these molecules also have regulatory roles in the proliferation of CSCs. Specific lncRNAs enhanced cell migration and invasion in breast carcinomas, which was associated with the generation of stem cell properties. The tumor microenvironment of CSCs also has an important role in tumor progression. Recent studies have shown that the interaction between tumor cells and the local microenvironment at the metastatic site leads to the development of premetastatic niche(s) and allows for the proliferation of the metastatic cells during colonization. The role of exosomes in the microenvironment during the EMT program is currently a major area of research. This review examines CSCs and the relationship between EMT and CSCs in solid tumors with emphasis on thyroid CSCs. The role of non-coding RNAs and of the microenvironment in EMT and in tumor progression are also examined. This review also highlights the growing number of studies that show the close association of EMT and CSCs and the role of exosomes and other elements of the tissue microenvironment in CSC metastasis. A better understanding of these mechanisms will lead to more effective targeting of primary and metastatic malignancies.

Phosphorylated Mechanistic Target of Rapamycin (p-mTOR) and Noncoding RNA Expression in Follicular and Hürthle Cell Thyroid Neoplasm

Oncocytic (Hürthle cell) and follicular neoplasms are related thyroid tumors with distinct molecular profiles. Diagnostic criteria separating adenomas and carcinomas for these two types of neoplasms are similar, but there may be some differences in the biological behavior of Hürthle cell and follicular carcinomas. Recent studies have shown that noncoding RNAs may have diagnostic and prognostic utility in separating benign and malignant Hürthle cell and follicular neoplasms. In this study, we examined expression of various noncoding RNAs including metastasis associated lung adenocarcinoma transcript 1 (MALAT1) and miR-RNA-885-5p (miR-885) in distinguishing between benign and malignant neoplasms. In addition, the expression of phosphorylated mechanistic receptor of rapamycin (p-mTOR) was also analyzed in these two groups of tumors. Tissue microarrays (TMAs) with archived tissue samples were analyzed using in situ hybridization (ISH) for MALAT1 and miR-885 and immunohistochemistry (IHC) for p-mTOR. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was also performed on a subset of the cases.MALAT1 and miR-885 were increased in all neoplastic groups compared to the normal thyroid tissues (p < 0.05). MALAT1 was more highly expressed in HCCs compared to FTCs, although the differences were not statistically significant (p = 0.06). MiR-885 was expressed at similar levels in FTCs and HCCs. P-mTOR protein was more highly expressed in FTCs than in HCCs (p<0.001). qRT-PCR analysis of noncoding RNAs supported the ISH findings. These results indicate that the noncoding RNAs MALAT1 and miR-885 show increased expression in neoplastic follicular and Hürthle cell thyroid neoplasms compared to normal thyroid tissues. P-mTOR was most highly expressed in FTC but was also increased in HCC, suggesting that drugs targeting this pathway may be useful for treatment of tumors unresponsive to conventional therapies.

Special role of JUN in papillary thyroid carcinoma based on bioinformatics analysis

Background

Papillary thyroid carcinoma (PTC) is the most common malignancy in thyroid tissue, and the number of patients with PTC has been increasing in recent years. Discovering the mechanism of PTC genesis and progression and finding new potential diagnostic biomarkers/therapeutic target genes of PTC are of great significance.

Methods

In this work, the datasets GSE3467 and GSE3678 were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified with the limma package in R. GO function and KEGG pathway enrichment were conducted with DAVID tool. The interaction network of the DEGs and other genes was performed with Cytoscape plugin BisoGenet, while clustering analysis was performed with Cytoscape plugin ClusterOne.

Results

A total of 1800 overlapped DEGs were detected in two datasets. Enrichment analysis of the DEGs found that the top three enriched GO terms in three ontologies and four significantly enriched KEGG pathways were mainly concerned with intercellular junction and extracellular matrix components. Interaction network analysis found that transcription factor hepatocyte nuclear factor 4, alpha (HNF4A) and DEG JUN had higher connection degrees. Clustering analysis indicated that two function modules, in which JUN was playing a central role, were highly relevant to PTC genesis and progression.

Conclusions

JUN may be used as a specific diagnostic biomarker/therapeutic molecular target of PTC. However, further experiments are still needed to confirm our results.

Pleiotropic Roles of Non-Coding RNAs in TGF-β-Mediated Epithelial-Mesenchymal Transition and Their Functions in Tumor Progression

Epithelial-mesenchymal transition (EMT) is a spatially- and temporally-regulated process involved in physiological and pathological transformations, such as embryonic development and tumor progression. While the role of TGF-β as an EMT-inducer has been extensively documented, the molecular mechanisms regulating this transition and their implications in tumor metastasis are still subjects of intensive debates and investigations. TGF-β regulates EMT through both transcriptional and post-transcriptional mechanisms, and recent advances underline the critical roles of non-coding RNAs in these processes. Although microRNAs and lncRNAs have been clearly identified as effectors of TGF-β-mediated EMT, the contributions of other atypical non-coding RNA species, such as piRNAs, snRNAs, snoRNAs, circRNAs, and even housekeeping tRNAs, have only been suggested and remain largely elusive. This review discusses the current literature including the most recent reports emphasizing the regulatory functions of non-coding RNA in TGF-β-mediated EMT, provides original experimental evidence, and advocates in general for a broader approach in the quest of new regulatory RNAs.

Thyrospheres from B-CPAP Cell Line with BRAF and TERT Promoter Mutations have Different Functional and Molecular Features than Parental Cells

Human thyroid cancer derived cell lines are widely used to study the mechanisms involved in thyroid carcinogenesis. However, there is limited availability of non-cross-contaminated cancer cell lines derived from papillary thyroid carcinoma (PTC), and the B-CPAP cell line is one of the few such lines. B-CPAP cells have been genetically and cytogenetically well-characterized, but details of their stemness features remain uncertain. Considering that this cell line is extensively used for in vitro studies on thyroid tumorigenesis, we broaden its functional and molecular profiles as well as the tumorigenic capacity. We used functional assays (sphere-forming capacity and efficiency), assessed self-renewal and propagation efficiency and tested in vivo tumorigenicity in Hsd:Athymic Nude-Foxn1^nu mice. Expression of markers of stemness, differentiation, and epithelial-mesenchymal transition were estimated at RNA and protein levels in adherent parental cells and sphere-forming cells. Functional aspects and stemness features were compared with normal thyrocytes. Protein expression of xenograft tumors was evaluated by immunohistochemistry. B-CPAP sphere-forming cells were able to form thyrospheres theoretically indefinitely in an appropriate serum-free medium, reverting to the adherent parental cell phenotype when cultured in differentiation medium. Different expression of ALDH1-A1 and CD44 stemness markers and TTF-1 and CK19 differentiation markers allowed discrimination between isolated sphere-forming cells and adherent parental cells, indicating that sphere-forming cells retained stem-like features. In keeping with these observations, tumorigenicity assays confirmed that, relative to parental adherent cells, thyrospheres had enhanced capacity to initiate xenograft tumors. Thyrospheres from normal cell line retained very low functional capacity, as well as different stemness markers expression compared to tumor thyrospheres. Our findings may constitute a useful background to develop an in vitro model for assessing the origin and progression of papillary thyroid carcinoma bearing BRAF^V600E and TERT promoter mutations.

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

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

MALAT1 Long Non-coding RNA Expression in Thyroid Tissues: Analysis by In Situ Hybridization and Real-Time PCR

Long non-coding RNAs (lncRNAs) are important for transcription and for epigenetic or posttranscriptional regulation of gene expression and may contribute to carcinogenesis. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), an lncRNA involved in the regulation of the cell cycle, cell proliferation, and cell migration, is known to be deregulated in multiple cancers. Here, we analyzed the expression of MALAT1 on 195 cases of benign and malignant thyroid neoplasms by using tissue microarrays for RNA in situ hybridization (ISH) and real-time PCR. MALAT1 is highly expressed in normal thyroid (NT) tissues and thyroid tumors, with increased expression during progression from NT to papillary thyroid carcinomas (PTCs) but is downregulated in poorly differentiated thyroid cancers (PDCs) and anaplastic thyroid carcinomas (ATCs) compared to NT. Induction of epithelial to mesenchymal transition (EMT) by transforming growth factor (TGF)-beta in a PTC cell line (TPC1) led to increased MALAT1 expression, supporting a role for MALAT1 in EMT in thyroid tumors. This is the first ISH study of MALAT1 expression in thyroid tissues. It also provides the first piece of evidence suggesting MALAT1 downregulation in certain thyroid malignancies. Our findings support the notion that ATCs may be molecularly distinct from low-grade thyroid malignancies and suggest that MALAT1 may function both as an oncogene and as a tumor suppressor in different types of thyroid tumors.

MiR-146b protects cardiomyocytes injury in myocardial ischemia/reperfusion by targeting Smad4

MicroRNAs, a class of small and non-encoding RNAs that transcriptionally or post-transcriptionally modulate the expression of their target genes, have been implicated as critical regulatory molecules in many cardiovascular diseases, including ischemia-/reperfusion-induced cardiac injury. In the present study, we report on the role of miR-146b in myocardial I/R injury and the underlying cardio-protective mechanism. Antagomir-146b was used to explore the effects of miR-146b on cardiac ischemia/reperfusion injury (30 min ischemia followed by 180 min reperfusion). As predicted, miR-146b overexpression significantly reduced the infarct size and cardiomyocytes apoptosis and release of creatine kinase and lactate dehydrogenase. In addition, miR-146b attenuated H9c2 cell apoptosis. Furthermore, Smad4 was predicted and verified as a potential miR-146b target using bioinformatics and luciferase assay. In summary, this study demonstrated that miR-146b plays a critical protective role in cardiac ischemic injury and may provide a new therapeutic approach for the treatment of myocardial I/R injury.

Expression of MicroRNAs in Thyroid Carcinoma

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

Medullary Thyroid Carcinoma: Recent Advances Including MicroRNA Expression

Medullary thyroid carcinoma (MTC) is an uncommon neuroendocrine tumor arising from the C cells in the thyroid and accounts for about 5 % of all thyroid cancers. MTC exhibits more aggressive behavior than follicular tumors, with the majority of cases presenting with lymph node metastasis. It is particularly common among patients carrying germline RET mutations with almost 100 % penetrance. Because activating RET mutations occur in over 90 % of hereditary and 40 % of sporadic MTC, clinical trials of several RET-targeting multikinase inhibitors (MKIs) have resulted in FDA approval of vandetanib and cabozantinib for the treatment of MTC. Nevertheless, in light of significant individual differences in tumor behavior and treatment responses, there has been a persistent need for research efforts to decipher the molecular events within RET-driven or non-RET-driven tumors. Recently, the gene regulatory roles of microRNAs (miRNAs) in MTC have been studied extensively. Multiple miRNA deregulations have been discovered in MTC with potential prognostic and therapeutic implications. This review provides an overview of the basic pathology of MTC and an update on recent investigational progress.

Stage-Specific Embryonic Antigen-1 (SSEA-1) Expression in Thyroid Tissues

Stage-specific embryonic antigen-1 (SSEA-1), also known as CD15, is a member of a cluster of differentiation antigens that have been identified in various normal tissues and in different types of cancers including papillary and medullary thyroid carcinoma. SSEA-1 may be expressed in normal stem cells and cancer stem-like cells. To evaluate the potential diagnostic and prognostic utility of SSEA-1 in thyroid tumors, we analyzed the expression of SSEA-1 in normal and neoplastic thyroid tissues by immunohistochemistry (IHC) using a tissue microarray with 158 different tissue cores. To evaluate the potential utility of SSEA-1 as a surface marker, we also assessed the expression of SSEA-1 in thyroid cell lines by flow cytometric analysis. SSEA-1 immunoreactivity was identified in malignant thyroid follicular epithelial cancers but not in the benign thyroid tissues. Anaplastic thyroid (ATC) (80 %) and conventional papillary thyroid carcinoma (PTC) (60.7 %) showed significantly higher percentage of cases that were SSEA-1 immunoreactive than follicular variant of papillary thyroid carcinoma (FVPTC) (20.6 %) and follicular carcinoma (FCA) (32.1 %). Flow cytometric analysis of cultured thyroid cell lines showed that a small subpopulation of ATC and PTC thyroid tumor cells had SSEA-1 immunoreactivity which may represent thyroid cancer stem-like cells. The ATC cells expressed more SSEA-1 immunoreactive cells than the PTC cell lines. Our findings suggest that expression of SSEA-1 immunoreactivity in thyroid neoplasms was associated with more aggressive thyroid carcinomas. SSEA-1 is a marker that detects malignant thyroid neoplasms in formalin-fixed paraffin-embedded thyroid tissue sections and may be a useful marker for thyroid cancer stem-like cells.

Clinicopathologic Correlations of E-cadherin and Prrx-1 Expression Loss in Hepatocellular Carcinoma

Background

Developing predictive markers for hepatocellular carcinoma (HCC) is important, because many patients experience recurrence and metastasis. Epithelial to mesenchymal transition (EMT) is a developmental process that plays an important role during embryogenesis and also during cancer metastasis. Paired-related homeobox protein 1 (Prrx-1) is an EMT inducer that has recently been introduced, and its prognostic significance in HCC is largely unknown.

Methods

Tissue microarray was constructed using surgically resected primary HCCs from 244 cases. Immunohistochemical staining of E-cadherin and Prrx-1 was performed. The correlation between E-cadherin loss and Prrx-1 expression, as well as other clinicopathologic factors, was evaluated.

Results

E-cadherin expression was decreased in 96 cases (39.4%). Loss of E-cadherin correlated with a higher recurrence rate (p < .001) but was not correlated with patient’s survival. Thirty-two cases (13.3%) showed at least focal nuclear Prrx-1 immunoreactivity while all non-neoplastic livers (n = 22) were negative. Prrx-1 expression was not associated with E-cadherin loss, survival or recurrence rates, pathologic factors, or the Ki-67 labeling index. Twenty tumors that were positive for E-cadherin and Prrx-1 had significantly higher nuclear grades than the rest of the cohort (p = .037). In Cox proportional hazard models, E-cadherin loss and large vessel invasion were independent prognostic factors for shorter disease-free survival. Cirrhosis and high Ki-67 index (> 40%) were independent prognostic factors for shorter overall survival.

Conclusions

Prrx-1 was expressed in small portions of HCCs but not in normal livers. Additional studies with a large number of Prrx-1-positive cases are required to confirm the results of this study.

miR-146b-5p functions as a tumor suppressor by targeting TRAF6 and predicts the prognosis of human gliomas

Down-regulation of miR-146b-5p contributes to tumorigenesis in several human cancers. However, the relevance of miR-146b-5p to prognosis, proliferation and apoptosis in gliomas remains unknown. In the present study, we demonstrated that miR-146b-5p expression was inversely correlated with grades and Ki-67 index in 147 human glioma specimens, but positively correlated with patients’ survival. Furthermore, two distinct subgroups of patients with grade I-IV gliomas with different prognoses were identified according to miR-146b-5p expression in our specimens. Cox regression showed that miR-146b-5p was an independent predictor for patients’ survival. Overexpression of miR-146b-5p dramatically suppressed glioma cell proliferation and induced apoptosis. Mechanistically, we validated TRAF6 as a direct functional target of miR-146b-5p and found that miR-146b-5p overexpression significantly decreased phosphorylated TAK1 and IκBα, the pivotal downstream effectors of TRAF6. Moreover, TRAF6 expression was positively correlated with glioma grades and Ki-67 index but inversely correlated with miR-146b-5p expression and predicted poor prognosis of glioma patients. In glioblastoma cell lines, silencing of TRAF6 could mimic the anti-tumor effect of miR-146b-5p. Our findings identify miR-146b-5p as a tumor suppressor and novel prognostic biomarker of gliomas, and suggest miR-146b-5p and TRAF6 as potential therapeutic candidates for malignant gliomas.

miR-655 suppresses epithelial-to-mesenchymal transition by targeting Prrx1 in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly aggressive breast cancer subtype that lacks effective targeted therapies. The epithelial-to-mesenchymal transition (EMT) is a key contributor in the metastatic process. In this study, we found that miR-655 was down-regulated in TNBC, and its expression levels were associated with molecular-based classification and lymph node metastasis in breast cancer. These findings led us to hypothesize that miR-655 overexpression may inhibit EMT and its associated traits of TNBC. Ectopic expression of miR-655 not only induced the up-regulation of cytokeratin and decreased vimentin expression but also suppressed migration and invasion of mesenchymal-like cancer cells accompanied by a morphological shift towards the epithelial phenotype. In addition, we found that miR-655 was negatively correlated with Prrx1 in cell lines and clinical samples. Overexpression of miR-655 significantly suppressed Prrx1, as demonstrated by Prrx1 3'-untranslated region luciferase report assay. Our study demonstrated that miR-655 inhibits the acquisition of the EMT phenotype in TNBC by down-regulating Prrx1, thereby inhibiting cell migration and invasion during cancer progression.

Prognostic Value of MicroRNAs in Preoperative Treated Rectal Cancer

Background: Patients with locally advanced rectal cancer are treated with preoperative chemoradiotherapy followed by surgical resection. Despite similar clinical parameters (uT2-3, uN+) and standard therapy, patients’ prognoses differ widely. A possible prediction of prognosis through microRNAs as biomarkers out of treatment-naïve biopsies would allow individualized therapy options. Methods: Microarray analysis of 45 microdissected preoperative biopsies from patients with rectal cancer was performed to identify potential microRNAs to predict overall survival, disease-free survival, cancer-specific survival, distant-metastasis-free survival, tumor regression grade, or nodal stage. Quantitative real-time polymerase chain reaction (qPCR) was performed on an independent set of 147 rectal cancer patients to validate relevant miRNAs. Results: In the microarray screen, 14 microRNAs were significantly correlated to overall survival. Five microRNAs were included from previous work. Finally, 19 miRNAs were evaluated by qPCR. miR-515-5p, miR-573, miR-579 and miR-802 demonstrated significant correlation with overall survival and cancer-specific survival (p < 0.05). miR-573 was also significantly correlated with the tumor regression grade after preoperative chemoradiotherapy. miR-133b showed a significant correlation with distant-metastasis-free survival. miR-146b expression levels showed a significant correlation with nodal stage. Conclusion: Specific microRNAs can be used as biomarkers to predict prognosis of patients with rectal cancer and possibly stratify patients’ therapy if validated in a prospective study.

Generation of Novel Thyroid Cancer Stem-Like Cell Clones: Effects of Resveratrol and Valproic Acid

Anaplastic thyroid cancer is an aggressive and highly lethal cancer for which conventional therapies have proved ineffective. Cancer stem-like cells (CSCs) represent a small fraction of cells in the cancer that are resistant to chemotherapy and radiation therapy and are responsible for tumor reoccurrence and metastasis. We characterized CSCs in thyroid carcinomas and generated clones of CSC lines. Our study showed that anaplastic thyroid cancers had significantly more CSCs than well-differentiated thyroid cancers. We also showed that Aldefluor-positive cells revealed significantly higher expression of stem cell markers, self-renewal properties, thyrosphere formation, and enhanced tumorigenicity. In vivo passaging of Aldefluor-positive cells resulted in the growth of larger, more aggressive tumors. We isolated and generated two clonal spheroid CSC lines derived from anaplastic thyroid cancer that were even more enriched with stem cell markers and more tumorigenic than the freshly isolated Aldefluor-positive cells. Resveratrol and valproic acid treatment of one of the CSC lines resulted in a significant decrease in stem cell markers, Aldefluor expression, proliferation, and invasiveness, with an increase in apoptosis and thyroid differentiation markers, suggesting that these cell lines may be useful for discovering new adjuvant therapies for aggressive thyroid cancers. For the first time, we have two thyroid CSC lines that will be useful tools for the study of thyroid CSC targeted therapies.

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.

The interplay between microRNAs and Twist1 transcription factor: a systematic review

Twist1 (also known as Twist) is a transcription factor that belongs to the family of basic helix-loop-helix (bHLH) proteins. It functions as a negative regulator of epithelial gene expression and a positive regulator of mesenchymal gene expression, thereby leading to induction of the epithelial mesenchymal transition (EMT), a process in which epithelial cells acquire the motile and migratory characteristics of mesenchymal cells. In addition to regulating the expression of protein-coding genes, Twist1 regulates the expression of microRNAs (miRNAs), adding a regulatory layer to EMT induction. Interestingly, the mRNA of Twist1 represents a downstream target of miRNAs, indicating an intricate network between miRNAs and Twist1. This network was shown to play multiple roles in cancer cell migration, invasion, and metastasis. The network can induce angiogenesis, protect cells from oncogene-induced apoptosis and senescence, enhance cancer cell resistance to conventional therapies, and increase cancer stem cell (CSC) populations. Recently, miRNAs have attracted considerable attention as potential promising tools in cancer therapies. Thus, this systematic review was conducted to clarify the reciprocal link between Twist1 and miRNAs in order to provide potential candidate miRNAs for diagnostic and therapeutic approaches in cancer treatment.

Notch1 Signaling Regulates the Aggressiveness of Differentiated Thyroid Cancer and Inhibits SERPINE1 Expression

PURPOSE

Notch1, a transmembrane receptor, has been recently shown to aid in the determination of thyroid cell fate associated with tumorigenesis. This study aimed to investigate the clinical relevance of Notch1 and its role in the regulation of differentiated thyroid cancer (DTC) behavior.

EXPERIMENTAL DESIGN

We examined Notch1 expression level and its relationship with clinicopathologic features and outcomes of DTC. Notch1 intracellular domain (NICD) was further characterized both in vitro and in vivo by gain-of-function assays using an inducible system.

RESULTS

Notch1 expression levels were downregulated in primary DTC tissue samples compared with contralateral nontumor and benign thyroid tissues. Decreased Notch1 expression in DTC was associated with advanced patient age (P = 0.032) and the presence of extrathyroidal invasion (P = 0.005). Patients with lower Notch1 expression had a significantly higher recurrence rate (P = 0.038). Restoration of NICD in a stably doxycycline-inducible metastatic DTC cell line reduced cell growth and migration profoundly. Using an orthotopic thyroid cancer model, NICD induction significantly reduced the growth of the primary thyroid tumor and inhibited the development of lung metastasis. Serpin peptidase inhibitor, clade E, member 1 (SERPINE1) was discovered by microarray as the most significant gene downregulated by NICD. Further validation showed that the induction of NICD reduced SERPINE1 expression in a dose-dependent manner, whereas restoration of a relative higher level of SERPINE1 was observed with NICD back to minimal level. In addition, SERPINE1 knock-down inhibited DTC cell migration.

CONCLUSIONS

Notch1 regulates the aggressive phenotypes of DTC, which could be mediated by SERPINE1 inhibition. Notch1/SERPINE1 axis warrants further investigation as a novel therapeutic target for advanced DTC. Clin Cancer Res; 22(14); 3582-92. ©2016 AACR.

NOVA1 inhibition by miR-146b-5p in the remnant tissue microenvironment defines occult residual disease after gastric cancer removal

Occult residual disease in remnant tissues could be the cause of tumor relapse. To identify signal molecules and target cells that may be indicative of occult residual disease within a remnant microenvironment, proximal resection margin tissues of gastric cancers were used, as these correspond to the nearest remnant tissues after gastrectomy. Increased miR-146b-5p in the remnant microenvironment was determined to be a strong risk factor for tumor relapse and poor survival rate. NOVA1, a target gene of miR-146b-5p, was decreased in remnant tissues of patients with a poor prognosis. NOVA1 was enriched in stromal spindle cells such as fibroblasts within normal tissues. In non-neoplastic inflammation, such as gastritis, NOVA1 was highly enriched in T lymphocytes and stromal spindle cells, while expression of this protein was frequently decreased in those types of cells within gastric cancer tissues. Particularly, decreased NOVA1 in T cells within the gastric cancer tissues was correlated with decreased FOXP3-positive regulatory T cells and was associated with poor patient prognosis. In vitro analysis showed that the NOVA1 gene was inhibited by miR-146b-5p. In immune cells as well as stromal spindle cells, decreased NOVA1, possibly inhibited by miR-146b-5p, is a candidate biomarker predicting poor prognosis of gastric cancer patients and is also a biomarker of occult residual disease in remnant tissues after gastric cancer removal.

INSM1: A Novel Immunohistochemical and Molecular Marker for Neuroendocrine and Neuroepithelial Neoplasms

OBJECTIVES

Neuroendocrine neoplasms (NENs) are heterogeneous neoplasms, which are sometimes malignant, although predicting metastasis is difficult. INSM1 is a transcription factor expressed transiently in embryonic neuroendocrine (NE) tissue, thought to coordinate termination of cell division with differentiation of NE and neuroepithelial cells. In adult tissues, INSM1 has been identified in multiple tumors of NE or neuroepithelial origin but has not been thoroughly investigated as a potential neoplastic marker.

METHODS

We evaluated INSM1 as a semiquantitative immunohistochemical (IHC) marker for NE and neuroepithelial neoplasms and as a quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) marker for gastrointestinal NENs (GI-NENs).

RESULTS

Using IHC, we found in normal adult tissue that INSM1 expression was highly restricted to nuclei of NE cells and tissues. INSM1 was not detected in any adult nonneoplastic, non-NE tissue. In neoplastic tissue, INSM1 was detectable by IHC in 88.3% of 129 NEN specimens. In contrast, INSM1 was detected by IHC in only one of 27 neoplasms without a neuroepithelial or NE component. Using qRT-PCR, we evaluated INSM1 gene expression in 113 GI-NEN specimens.

CONCLUSIONS

INSM1 expression was significantly increased in neoplastic vs nonneoplastic tissue. Furthermore, among midgut GI-NENs, neoplasms with known metastases showed significantly higher expression than those that had not yet metastasized.

Site-Specific MicroRNA Expression May Lead to Different Subtypes in Ulcerative Colitis

Background and Aim

Ulcerative Colitis (UC) is a type of inflammatory bowel disease, considered as an important disease of gastrointestinal tract having a huge impact on the health of the patient. Prolonged inflammation of colon in UC patients increases the risk of developing colorectal cancer. MiRNA are reported as a connecting link between inflammation and cancer. Differential miRNA expression is reported in Crohn’s disease (CD) patients involving various regions of the gastrointestinal tract. The current study was performed to dissect out the site specific miRNA expression in the colon biopsy samples of UC patients from Northern India.

Methods

Biopsy samples were collected from UC patients and healthy controls from Rectosigmoid Area (RS) and Ascending Colon (AC). MiRNA expression was compared between patients with RS and AC using a microarray platform. Differential expression was further validated by Real Time PCR analysis. Demographic and pathological data of UC -associated CRC patients was collected from the hospital database and analyzed for assessing the site of cancer.

Results

Upon analysis of data generated on a microarray platform and qRT PCR revealed that the expression of six miRNAs hsa-miR-146b-5p, hsa-miR-335-3p, hsa-miR-342-3p, hsa-miR-644b-3p, hsa-miR-491-3p, hsa-miR-4732-3p were downregulated in patients where RS was involved as compared to AC. The expression of hsa-miR-141-3p was upregulated in patients where RS region was involved as compared to AC. Analysis of the registered UC patient’s database from the hospital revealed that the site of CRC was predomimnantly the rectosigmoid region of the colon in most of the cases.

Conclusion

This is the first study to show the differential expression of miRNA involving different sites of colon in UC patients. Taking our data and previous reports into consideration, we propose that differential miRNA expression during UC perhaps contribute in the development of UC-associated CRC at the rectosigmoid area.

Integration of transcriptome and methylome analysis of aldosterone-producing adenomas

OBJECTIVE

The pathophysiology of aldosterone-producing adenomas (APA) has been investigated intensively through genetic and genomic approaches. However, the role of epigenetics in APA is not fully understood. In the present study, we explored the relationship between gene expression and DNA methylation status in APA.

METHODS

We conducted an integrated analysis of transcriptome and methylome data of paired APA-adjacent adrenal gland (AAG) samples from the same patient. The adrenal specimens were obtained from seven Japanese patients with APA who underwent adrenalectomy. Gene expression and genome-wide CpG methylation profiles were obtained from RNA and DNA samples that were extracted from those seven paired tissues.

RESULTS

Methylome analysis showed global CpG hypomethylation in APA relative to AAG. The integration of gene expression and methylation status showed that 34 genes were up-regulated with CpG hypomethylation in APA. Of these, three genes (CYP11B2, MC2R, and HPX) may be related to aldosterone production, and five genes (PRRX1, RAB38, FAP, GCNT2, and ASB4) are potentially involved in tumorigenesis.

CONCLUSION

The present study is the first methylome analysis to compare APA with AAG in the same patients. Our integrated analysis of transcriptome and methylome revealed DNA hypomethylation in APA and identified several up-regulated genes with DNA hypomethylation that may be involved in aldosterone production and tumorigenesis.

In Situ Hybridization Analysis of miR-146b-5p and miR-21 in Thyroid Nodules: Diagnostic Implications

Some thyroid nodules such as follicular adenomas (FAs), follicular variant of papillary thyroid carcinomas (FVPTCs), and follicular thyroid carcinomas (FTCs) exhibit similar clinical presentations and gross morphologic appearances. The differential diagnosis of these lesions is sometimes difficult based on morphologic, cytologic, or clinical features alone. miR-146b-5p and miR-21 deregulation has been associated with progression and metastasis of thyroid cancers. However, the utility of in situ hybridization (ISH) to determine the cellular localization, diagnostic, and prognostic significance of miR-146b-5p and miR-21 expression in thyroid tumors has not been extensively analyzed. In order to examine the expression of miR-146b-5p and miR-21 in benign and malignant thyroid tissues and to determine if these microRNAs could be assigned to distinct histomorphological types of thyroid nodules, we analyzed miR-146b-5p and miR-21 expression in thyroid nodules on tissue microarrays (TMAs) with 193 thyroid specimens by ISH. miR-146b-5p and miR-21 expression in thyroid tissues was also analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). miR-146b-5p was highly expressed (89%) in papillary thyroid carcinomas (PTCs) and 41% of FVPTC. The expression of miR-146b-5p was not expressed in most FTCs, anaplastic thyroid carcinomas (ATCs), poorly differentiated thyroid carcinomas (PDTCs), or FAs (7, 8, 0, and 0%, respectively). MiR-21 was overexpressed in 83% of ATCs, 79 % of PTCs, 34% of FVPTCs, and 19% of PDTCs. The expression of miR-21 was not expressed in most FAs (9%) or FTCs (4%). Normal thyroid tissues and most benign goiters were negative for miR-146b-5p and miR-21. qRT-PCR analysis supported the ISH findings. PTC cases with positive expression of miR-146b-5p and miR-21 had significantly poorer disease-free survival rates. Immunohistochemical staining for HBME-1 showed positive staining in PTCs (100 %) and FVPTCs (92 %) with a subset of FTC (40%) staining positive, while all FAs were negative. Since miR-146b-5p was mainly expressed in PTC including FVPTC and was not expressed in most FTC, PDTC, or ATC, it may serve as a useful diagnostic marker for PTC. ISH is a useful method to analyze microRNA expression in formalin-fixed paraffin-embedded thyroid tissues.