Evaluation of miRNAs expression in medullary thyroid carcinoma tissue samples: miR-34a and miR-144 as promising overexpressed markers in MTC

Non-coding RNAs as potential therapeutic targets for receptor tyrosine kinase signaling in solid tumors: current status and future directions

This review article presents an in-depth analysis of the current state of research on receptor tyrosine kinase regulatory non-coding RNAs (RTK-RNAs) in solid tumors. RTK-RNAs belong to a class of non-coding RNAs (nc-RNAs) responsible for regulating the expression and activity of receptor tyrosine kinases (RTKs), which play a critical role in cancer development and progression. The article explores the molecular mechanisms through which RTK-RNAs modulate RTK signaling pathways and highlights recent advancements in the field. This include the identification of potential new RTK-RNAs and development of therapeutic strategies targeting RTK-RNAs. While the review discusses promising results from a variety of studies, encompassing in vitro, in vivo, and clinical investigations, it is important to acknowledge the challenges and limitations associated with targeting RTK-RNAs for therapeutic applications. Further studies involving various cancer cell lines, animal models, and ultimately, patients are necessary to validate the efficacy of targeting RTK-RNAs. The specificity of ncRNAs in targeting cellular pathways grants them tremendous potential, but careful consideration is required to minimize off-target effects, the article additionally discusses the potential clinical applications of RTK-RNAs as biomarkers for cancer diagnosis, prognosis, and treatment. In essence, by providing a comprehensive overview of the current understanding of RTK-RNAs in solid tumors, this review emphasizes their potential as therapeutic targets for cancer while acknowledging the associated challenges and limitations.

Significance of miRNAs on the thyroid cancer progression and resistance to treatment with special attention to the role of cross-talk between signaling pathways

Thyroid cancer (TC) is the most prevalent endocrine malignant tumor. It has many types, the Papillary thyroid cancer (PTC)(most common and follicular thyroid carcinoma (FTC). Several risk factors have been associated with TC radiation exposure, autoimmunity, and genetics. Microribonucleic acids (miRNAs) are the most important genetic determinants of TC. They are small chains of nucleic acids that are able to inhibit the expression of several target genes. They could target several genes involved in TC proliferation, angiogenesis, apoptosis, development, and even resistance to therapy. Besides, they could influence the stemness of TC. Moreover, they could regulate several signaling pathways such as WNT/β-catenin, PI3K/AKT/mTOR axis, JAK/STAT, TGF- β, EGFR, and P53. Besides signaling pathways, miRNAs are also involved in the resistance of TC to major treatments such as surgery, thyroid hormone-inhibiting therapy, radioactive iodine, and adjuvant radiation. The stability and sensitivity of several miRNAs might be exploited as an approach for the usage of miRNAs as diagnostic and/or prognostic tools in TC.

Mesenchymal stem cell-derived exosomes as new tools for delivery of miRNAs in the treatment of cancer

Although ongoing medical research is working to find a cure for a variety of cancers, it continues to be one of the major causes of death worldwide. Chemotherapy and immunotherapy, as well as surgical intervention and radiation therapy, are critical components of cancer treatment. Most anti-cancer drugs are given systemically and distribute not just to tumor tissues but also to normal tissues, where they may cause side effects. Furthermore, because anti-cancer drugs have a low delivery efficiency, some tumors do not respond to them. As a result, tumor-targeted drug delivery is critical for improving the safety and efficacy of anti-cancer treatment. Exosomes are microscopic extracellular vesicles that cells produce to communicate with one another. MicroRNA (miRNA), long non-coding RNA (lncRNA), small interfering RNA (siRNA), DNA, protein, and lipids are among the therapeutic cargos found in exosomes. Recently, several studies have focused on miRNAs as a potential therapeutic element for the treatment of cancer. Mesenchymal stem cells (MSC) have been known to have angiogenic, anti-apoptotic, anti-inflammatory and immunomodulatory effects. Exosomes derived from MSCs are gaining popularity as a non-cellular alternative to MSC-based therapy, as this method avoids unwanted lineage differentiation. Therefore more research have focused on transferring miRNAs to mesenchymal stem cells (MSC) and targeting miRNA-loaded exosomes to cancer cells. Here, we initially gave an overview of the characteristics and potentials of MSC as well as the use of MSC-derived exosomes in cancer therapy. Finally, we emphasized the utilization of MSC-derived exosomes for miRNA delivery in the treatment of cancer.

Identification of functional pathways and molecular signatures in neuroendocrine neoplasms by multi-omics analysis

BACKGROUND

Neuroendocrine neoplasms (NENs) represent a heterogeneous class of rare tumors with increasing incidence. They are characterized by the ability to secrete peptide hormones and biogenic amines but other reliable biomarkers are lacking, making diagnosis and identification of the primary site very challenging. While in some NENs, such as the pancreatic ones, next generation sequencing technologies allowed the identification of new molecular hallmarks, our knowledge of the molecular profile of NENs from other anatomical sites is still poor.

METHODS

Starting from the concept that NENs from different organs may be clinically and genetically correlated, we applied a multi-omics approach by combining multigene panel testing, CGH-array, transcriptome and miRNome profiling and computational analyses, with the aim to highlight common molecular and functional signatures of gastroenteropancreatic (GEP)-NENs and medullary thyroid carcinomas (MTCs) that could aid diagnosis, prognosis and therapy.

RESULTS

By comparing genomic and transcriptional profiles, ATM-dependent signaling emerged among the most significant pathways at multiple levels, involving gene variations and miRNA-mediated regulation, thus representing a novel putative druggable pathway in these cancer types. Moreover, a set of circulating miRNAs was also selected as possible diagnostic/prognostic biomarkers useful for clinical management of NENs.

CONCLUSIONS

These findings depict a complex molecular and functional landscape of NENs, shedding light on novel therapeutic targets and disease biomarkers to be exploited.

Mir-34a: a regulatory hub with versatile functions that controls osteosarcoma networks

Osteosarcoma (OS) is one of the most prevalent and highly aggressive bone malignancies. The treatment strategies of OS is under standard regimens, including surgical resection, chemotherapy, and other adjuvant therapy. However, the 5-year survival rate is still unsatisfactory. Previous studies have demonstrated that the expression of miR-34a decreases in osteosarcoma, which is involved in regulating numerous genes directly or indirectly at the post-transcriptional level and other pathways. Thus, miR-34a plays an important role in mediating OS cell proliferation, differentiation, migration, and apoptosis, and might be a pivotal biomarker for OS with diagnostic and therapeutic potentials. In this review, we aim to summarize the relationship between miR-34a and OS, with an emphasis on the specific mechanisms in OS development referring to miR-34a. Moreover, the potential role of miR-34a as a diagnostic, prognostic, and therapeutic candidate for OS would be presented in detail. However, the molecular mechanisms related to miR-34a and OS remain elusive, and more investigations are needed to reach a comprehensive understanding.

MIMRDA: A Method Incorporating the miRNA and mRNA Expression Profiles for Predicting miRNA-Disease Associations to Identify Key miRNAs (microRNAs)

Identifying cancer-related miRNAs (or microRNAs) that precisely target mRNAs is important for diagnosis and treatment of cancer. Creating novel methods to identify candidate miRNAs becomes an imminent Frontier of researches in the field. One major obstacle lies in the integration of the state-of-the-art databases. Here, we introduce a novel method, MIMRDA, which incorporates the miRNA and mRNA expression profiles for predicting miRNA-disease associations to identify key miRNAs. As a proof-of-principle study, we use the MIMRDA method to analyze TCGA datasets of 20 types (BLCA, BRCA, CESE, CHOL, COAD, ESCA, HNSC, KICH, KIRC, KIRP, LIHC, LUAD, LUSC, PAAD, PRAD, READ, SKCM, STAD, THCA and UCEC) of cancer, which identified hundreds of top-ranked miRNAs. Some (as Category 1) of them are endorsed by public databases including TCGA, miRTarBase, miR2Disease, HMDD, MISIM, ncDR and mTD; others (as Category 2) are supported by literature evidences. miR-21 (representing Category 1) and miR-1258 (representing Category 2) display the excellent characteristics of biomarkers in multi-dimensional assessments focusing on the function similarity analysis, overall survival analysis, and anti-cancer drugs’ sensitivity or resistance analysis. We compare the performance of the MIMRDA method over the Limma and SPIA packages, and estimate the accuracy of the MIMRDA method in classifying top-ranked miRNAs via the Random Forest simulation test. Our results indicate the superiority and effectiveness of the MIMRDA method, and recommend some top-ranked key miRNAs be potential biomarkers that warrant experimental validations.

microRNAs and long non-coding RNAs as biomarkers for polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is known as the most common metabolic/endocrine disorder among women of reproductive age. Its complicated causality assessment and diagnostic emphasized the role of non‐coding regulatory RNAs as molecular biomarkers in studying, diagnosing and even as therapeutics of PCOS. This review discusses a comparative summary of research into microRNAs (miRNAs) and long non‐coding RNAs (lncRNAs) that are molecularly or statistically related to PCOS. We categorize the literature in terms of centering on either miRNAs or lncRNAs and discuss the combinatory studies and promising ideas as well. Additionally, we compare the pros and cons of the prominent research methodologies used for each of the abovementioned research themes and discuss how errors can be stopped from propagation by selecting correct methodologies for future research. Finally, it can be concluded that research into miRNAs and lncRNAs has the potential for identifying functional networks of regulation with multiple mRNAs (and hence, functional proteins). This new understanding may eventually afford clinicians to control the molecular course of the pathogenesis better. With further research, RNA (with statistical significance and present in the blood) may be used as biomarkers for the disease, and more possibilities for RNA therapy agents can be identified.

Changes in Exosomal miRNA Composition in Thyroid Cancer Cells after Prolonged Exposure to Real Microgravity in Space

As much as space travel and exploration have been a goal since humankind looked up to the stars, the challenges coming with it are manifold and difficult to overcome. Therefore, researching the changes the human organism undergoes following exposure to weightlessness, on a cellular or a physiological level, is imperative to reach the goal of exploring space and new planets. Building on the results of our CellBox-1 experiment, where thyroid cancer cells were flown to the International Space Station, we are now taking advantage of the newest technological opportunities to gain more insight into the changes in cell–cell communication of these cells. Analyzing the exosomal microRNA composition after several days of microgravity might elucidate some of the proteomic changes we have reported earlier. An array scan of a total of 754 miRNA targets revealed more than 100 differentially expressed miRNAs in our samples, many of which have been implicated in thyroid disease in other studies.

MicroRNAs in Medullary Thyroid Carcinoma: A State of the Art Review of the Regulatory Mechanisms and Future Perspectives

Medullary thyroid carcinoma (MTC) is a rare malignant neoplasia with a variable clinical course, with complete remission often difficult to achieve. Genetic alterations lead to fundamental changes not only in hereditary MTC but also in the sporadic form, with close correlations between mutational status and prognosis. In recent years, microRNAs (miRNAs) have become highly relevant as crucial players in MTC etiology. Current research has focused on their roles in disease carcinogenesis and development, but recent studies have expounded their potential as biomarkers and response predictors to novel biological drugs for advanced MTC. One such element which requires greater investigation is their mechanism of action and the molecular pathways involved in the regulation of gene expression. A more thorough understanding of these mechanisms will help realize the promising potential of miRNAs for MTC therapy and management.

MiR-144-3p inhibits the proliferation, migration and invasion of lung adenocargen cancer cells by targeting COL11A1

This study aimed to investigate the regulatory relationship between miR-144-3p and COL11A1, and to explore its effect on the proliferation, migration and invasion of lung adenocarcinoma (LUAD) cells. A series of methods and experiments were applied. miR-144-3p was downregulated in LUAD tissue and cells, whereas COL11A1 was highly expressed. Overexpressing miR-144-3p inhibited the proliferation, migration and invasion of LUAD cells, which could be reversed by overexpression of COL11A1. Overexpressing miR-144-3p inhibits the proliferation, migration and invasion of LUAD cells by silencing COL11A1.

Assessment of AXL and mTOR genes expression in medullary thyroid carcinoma (MTC) cell line in relation with over expression of miR-144 and miR-34a

OBJECTIVES

The aim of the present study was to investigate the expression of AXL and mTOR genes and their targeting microRNAs (miRNAs) including miR-34a and miR-144 in Medullary Thyroid Carcinoma (MTC) cell line, TT, and determine the effect of these two miRNAs on their target genes to introduce new molecular markers or therapeutics.

METHODS

The expression of miR-34a, miR-144, and their targets genes including AXL and mTOR was evaluated by quantitative Real-time PCR. Luciferase assay was performed to confirm the interaction between miRNAs and their target mRNAs. The expression level of AXL and mTOR was evaluated before and after miRNAs induction in TT cell line compared with Cos7 as control cells.

RESULTS

The expression of AXL and mTOR were up-regulated significantly, while miR-34a and miR-144 were down-regulated in TT cell line compared to Cos7. After transduction, the overexpression of miR-34a and 144 caused down-regulation of both genes. Luciferase assay results showed that the mTOR is targeted by miR-34a and miR-144 and the intensity of luciferase decreased in the presence of miRNAs.

CONCLUSIONS

Based on the results of the present study and since AXL and mTOR genes play a critical role in variety of human cancers, suppression of these genes by their targeting miRNAs, especially miR-34a and miR-144, can be propose as a new strategy for MTC management. However, more studies are needed to approve the hypothesis.

Role of tissue and circulating microRNAs and DNA as biomarkers in medullary thyroid cancer

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor comprising hereditary or sporadic form with frequent mutations in the rearranged during transfection (RET) or RAS genes. Diagnosis is based on the presence of thyroid tumor mass with altered levels of calcitonin (Ctn) and carcinoembryonal antigen (CEA) in the serum and/or in the cytological smears from fine needle aspiration biopsies. Treatment consists of total thyroidectomy, followed by tyrosine kinase inhibitors (TKi) in case of disease persistence. During TKi treatment, Ctn and CEA levels can fluctuate regardless of tumor volume, metastasis or response to therapy. Research for more reliable non-invasive biomarkers in MTC is still underway. In this context, circulating nucleic acids, namely circulating microRNAs (miRNAs) and cell free DNA (cfDNA), have been evaluated by different research groups. Aiming to shed light on whether miRNAs and cfDNA are suitable as MTC biomarkers we searched three different databases, PubMed, Scopus, WOS and reviewed the literature. We classified 83 publications fulfilling our search criteria and summarized the results. We report data on miRNAs and cfDNA that can be evaluated for validation in independent studies and clinical application.

Analytical and clinical validation of pairwise microRNA expression analysis to identify medullary thyroid cancer in thyroid fine-needle aspiration samples

Background

Medullary thyroid carcinoma (MTC) is an aggressive malignancy originating from the parafollicular C cells. Preoperatively, thyroid nodule fine‐needle aspiration cytology (FNAC) and pathogenic gene mutations are definitive in approximately one‐half of cases. MicroRNAs (miRNAs) are endogenous, noncoding, single‐stranded RNAs that regulate gene expression, a characteristic that confers the potential for identifying malignancy. In the current study, the authors hypothesized that differential pairwise (diff‐pair) analysis of miRNA expression levels would reliably identify MTC in FNA samples.

Methods

The relative abundance of 10 different miRNAs in total nucleic acids was obtained from ThyraMIR test results. Diff‐pair analysis was performed by subtracting the critical threshold value of one miRNA from the critical threshold values of other miRNAs. Next‐generation sequencing with the ThyGeNEXT panel identified oncogenic gene alterations. The discovery cohort consisted of 30 formalin‐fixed, paraffin‐embedded benign and malignant thyroid neoplasms, including 4 cases of MTC. After analytical validation, clinical validation was performed using 3 distinct cohorts (total of 7557 specimens).

Results

In the discovery cohort, 9 diff‐pairs were identified as having significant power using the Kruskal‐Wallis test (P < .0001) to distinguish MTC samples from non‐MTC samples. The assay correctly classified all MTC and non‐MTC samples in the analytical validation study and in the 3 clinical validation cohorts. The overall test accuracy was 100% (95% confidence interval, 99%‐100%). In indeterminate FNAC samples, the sensitivity of the diff‐pair analysis was greater than that of the MTC‐specific mutation analysis (100% vs 25%; P = .03).

Conclusions

Pairwise miRNA expression analysis of ThyraMIR results were found to accurately predict MTC in thyroid FNA samples, including those with indeterminate FNAC findings.

The authors have developed and validated a microRNA (miRNA) test for the detection of medullary thyroid cancer (MTC) in preoperative thyroid nodule samples. The method, based on differential pairwise analysis of miRNA expression data generated using the ThyraMIR Thyroid miRNA Classifier, accurately predicts MTC with 100% sensitivity and 100% specificity in thyroid fine‐needle aspiration biopsies.

MicroRNA-144: A novel biological marker and potential therapeutic target in human solid cancers

MicroRNAs (miRNAs) are a class of small non-coding RNAs that negatively regulate gene expression at the post-transcriptional level. It has been reported that microRNA-144 (miR-144) is highly conserved and can combine complementarily with the 3'-UTRs of target gene mRNAs to inhibit mRNA translation or promote targeted mRNA degradation. MiR-144 is abnormally expressed and has been identified as a tumor suppressor in many types of solid tumors. Increasing evidence supports a crucial role for miR-144 in modulating physiopathologic processes, such as proliferation, apoptosis, invasion, migration and angiogenesis in different tumor cells. Apart from these functions, miR-144 can also affect drug sensitivity, cancer treatment and patient prognosis. In this review, we summarize the biological functions of miR-144, its direct targets and the important signal pathways through which it acts in relation to various tumors. We also discuss the role of miR-144 in tumor biology and its clinical significance in detail and offer novel insights into molecular targeting therapy for human cancers.

Multifunctional Roles of miR-34a in Cancer: A Review with the Emphasis on Head and Neck Squamous Cell Carcinoma and Thyroid Cancer with Clinical Implications

MiR-34a belongs to the class of small non-coding regulatory RNAs and functions as a tumor suppressor. Under physiological conditions, miR-34a has an inhibitory effect on all processes related to cell proliferation by targeting many proto-oncogenes and silencing them on the post-transcriptional level. However, deregulation of miR-34a was shown to play important roles in tumorigenesis and processes associated with cancer progression, such as tumor-associated epithelial-mesenchymal transition, invasion, and metastasis. Moreover, further understanding of miR-34a molecular mechanisms in cancer are indispensable for the development of effective diagnosis and treatments. In this review, we summarized the current knowledge on miR-34a functions in human disease with an emphasis on its regulation and dysregulation, its role in human cancer, specifically head and neck squamous carcinoma and thyroid cancer, and emerging role as a disease diagnostic and prognostic biomarker and the novel therapeutic target in oncology.

The role of microRNAs in the pathogenesis of thyroid cancer

Thyroid cancer is the most frequent type of cancers originating from the endocrine system. Early diagnosis leads to good clinical outcome in differentiated types of thyroid cancer. Yet, there are few treatment options for patients with medullary or anaplastic thyroid cancer. Thus, identification of molecular markers that explain the pathologic process during evolution of this cancer has practical significance. MicroRNAs (miRNAs) have been shown to influence the activity of thyroid cancer-related signaling pathways such as MAPK pathway and RET gene. These small transcripts not only can differentiate malignant tissues from non-malignant tissues, but also have differential expression in different stages of thyroid cancer. Assessment of serum levels of miRNAs is a practical noninvasive method for follow-up of patients after thyroidectomy. Moreover, the therapeutic effects of a number of miRNAs have been verified in xenograft models of thyroid cancer. In the current review, we summarize the data regarding the role of miRNAs in thyroid cancer.

Pri-miR-144 rs9279 is associated with type 2 diabetes and regulation of stress response

Single-nucleotide polymorphisms (SNPs) of microRNAs (miRNAs) may alter miRNA expression, binding affinity, and/or messenger RNA expression levels of the target genes, thus leading to disease susceptibility. This study explored the association between SNPs in neuroendocrine stress response-related miRNAs and type 2 diabetes (T2D). In the screening stage, the association between six candidate SNPs of miRNAs and T2D was analyzed in a case-control study including 504 T2D cases and 494 healthy controls. Homozygous GG genotype of pri-miR-144 rs9279 showed significant association with increased risk of T2D compared with homozygous TT genotype (adjusted odds ratio [OR] = 1.62, 95% confidence interval [CI]: 1.07-2.45; p = .023) and the combined TT/TG genotype (adjusted OR = 1.59, 95% CI: 1.08-2.36; p = .020). In the validation stage, the association was further validated in a second independent set of subjects. The GG genotype showed consistent directions and effect sizes that were identified in previous additive and recessive models. The expression levels of miRNAs were further compared between different genotypes in the 179 newly diagnosed cases and 183 frequency-matched healthy controls. As a result, the GG genotype carriers had significantly upregulated expression of plasma miR-144 and cortisol, as compared to individuals with TT and TG genotypes, respectively, in total subjects and subgroups (p < .05). Eventually, NR3C1 was proved to be a stress-related target gene of miR-144, indicating that pri-miR-144 rs9279 may contribute to the development of T2D by altering regulation of stress response.

Overexpression of mir-129-1, miR-146b, mir-183, and mir-197 in follicular thyroid carcinoma and adenoma tissues

Follicular thyroid carcinoma (FTC) is responsible for approximately 10% of thyroid malignancies. Since this type of malignancy indicates no capsular and vascular invasions, adenoma and follicular carcinoma of thyroid are not distinguishable. It has been proved that microRNAs, which regulate approximately 30% of coding proteins, have an association with follicular thyroid adenoma (FTA) and carcinoma of the thyroid. Therefore, the aim of this study was to assess the expression of some miRNAs for detecting the most appropriate miRNA as potential biomarker in the diagnosis of FTA and FTC patients. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was applied to determine the expression levels of miR-129-1, miR-146b,-183 and miR-197 in 48 cases (16 FTC, 16 FTA and 16 hyperplasia/multinodular goiter (MNG) cases). The significance of miRNA differential expression levels among groups were assessed using Multivariate test by Statistical Package for Science Software (SPSS v.20) and Graph Pad Prism v.8. Results indicated that all of the miRNAs had significant overexpression in FTC and FTA versus MNG cases, and also increased expression level in FTC in comparison with FTA, however it was not significant. The results of ROC curve analysis determined the significant overexpression and prognostic value of miR-129-1 in FTA cases and miR-146b in both FTA and FTC cases compared to MNG group. Although all of the earlier mentioned microRNAs were overexpressed in FTC and FTA cases, the ROC curve results demonstrated that miR-129-1 had agreeable AUC for FTA cases. Therefore, it seems that it's cut-off point could be helpful in distinguishing between FTA and multinodular goiter cases. On the other hand, although miR-146b has excellent diagnostic value in both FTA and FTC groups, it seems that this microRNA is unable to act as a specific biomarker to discriminate between FTA and FTC cases. This data need to be confirmed in a large cohort study and other biological samples such as plasma.

The role of molecular genetics in the clinical management of sporadic medullary thyroid carcinoma: A systematic review

BACKGROUND

The significant variation in the clinical behaviour of sporadic medullary thyroid carcinoma (sMTC) causes uncertainty when planning the management of these patients. Several tumour genetic and epigenetic markers have been described, but their clinical usefulness remains unclear. The aim of this review was to evaluate the evidence for the use of molecular genetic and epigenetic profiles in the risk stratification and management of sMTC.

METHODS

MEDLINE and Embase databases were searched using the MeSH terms "medullary carcinoma", "epigenetics", "molecular genetics", "microRNAs"; and free text terms "medullary carcinoma", "sporadic medullary thyroid cancer", "sMTC", "RET", "RAS" and "miR". Articles containing less than ten subjects, not focussing on sMTC, or not reporting clinical outcomes were excluded. Risk of bias was assessed using a modified version of the Newcastle-Ottawa Scale.

RESULTS

Twenty-three studies met the inclusion criteria, and key findings were summarized in themes according to the genetic and epigenetic markers studied. There is good evidence that somatic RET mutations predict higher rates of lymph node metastasis and persistent disease, and worse survival. There are also several good quality studies demonstrating associations between certain epigenetic markers such as tumour miR-183 and miR-375 expression and higher rates of lymph node and distant metastasis, and worse survival.

CONCLUSIONS

There is a growing body of evidence that tumour genetic and epigenetic profiles can be used to risk stratify patients with sMTC. Further research should focus on the clinical applicability of these findings by investigating the possibility of tailoring management to an individual's tumour mutation profile.

An investigation on the expression of miRNAs including miR-144 and miR-34a in plasma samples of RET-positive and RET-negative medullar thyroid carcinoma patients

Medullary thyroid carcinoma (MTC) is a scarce cancerous disease, originating from parafollicular C cells of the thyroid gland. MTC can be manifested as an aggressive carcinoma with metastasis, especially in sporadic forms. Mutations of the rearranged during transfection (RET) proto-oncogene occurs in all hereditary and a few somatic MTCs, so detection of RET mutations is needed for prompt and appropriate treatment. MicroRNAs (miRNAs) are noncoding regulatory RNAs. Extensive studies have done in progress or suppression of several types of cancers such as MTCs with the remarkable application as prognostic markers. Of the effective miRNAs in cancers, miR-144 and miR-34 were evaluated in our study. Blood samples of 25 RET-positive and 25 RET-negative blood samples of patients with MTC were evaluated for these miRNAs, using quantitative real-time polymerase chain reaction (RT-qPCR). Analysis of the results was performed by the 2 ^-ΔΔCt method, showing that miR-144 and miR-34a expression had a relative increase in patients with MTC compared with normal control samples and also in RET positives versus RET negatives. We recruited 50 out of 350 MTC plasma samples (27 female and 23 male) which were selected based on RET mutation in exon 11 (25 RET-positive and 25 RET-negative), with a mean ± SD age of 37.04 ± 1.74 years. Receiver operating characteristic (ROC) curve analysis was done to investigate the prognostic value of these miRNAs; although, they showed no significant prognostic value as MTC biomarkers in plasma samples. In conclusion, miRNAs can be used as biomarkers of cancers such as MTC; however, more studies are needed to find the best candidate miRNAs for the diagnosis of cancers.

Identification and interaction analysis of key miRNAs in medullary thyroid carcinoma by bioinformatics analysis

Medullary thyroid carcinoma (MTC) is an endocrine tumor and comprises 5–10% of all primary thyroid malignancies. However, the biomechanical contribution to the development and progression of MTC remains unclear. In this study, To discover the key microRNAs (miRNAs or miRs) and their potential roles in the tumorigenesis of MTC, the microarray datasets GSE97070, GSE40807 and GSE27155 were analyzed. The datasets were downloaded from the Gene Expression Omnibus (GEO) database. The differentially expressed miRNAs (DEMs) and genes (DEGs) were accessed by R. Targets of DEMs and predicted using starBase, and functional and pathway enrichment analyses were performed using Metascape. A protein-protein interaction (PPI) network and an analysis of modules were constructed using NetworkAnalyst. Finally, a network was constructed to show the regulatory association between transcription factors (TFs), DEMs and downstream genes. A total of 5 DEMs were found both in GSE97070 and GSE40807, including 3 upregulated DEMs and 2 downregulated DEMs. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses from Metascape revealed that the target genes of upregulated DEMs were significantly enriched in adherens junction, kinase and protein binding, while the target genes of downregulated DEMs were mainly involved in non-canonical Wnt signaling pathway and RNA transport. From the PPI network, 13 nodes were screened as hub genes. Pathway enrichment analysis revealed that the top 5 modules were mostly enriched in the neurotrophin signaling pathway, mRNA surveillance pathway and MAPK signaling pathway. In addition, the TF-DEMs-target gene and DEGs regulatory network revealed that 17 TFs regulated 2 miRNAs, including upregulated or downregulated DEMs, CREB1 regulated all upregulated DEMs, and TGFB1 was an activator of hsa-miR-199a-3p and a repressor of hsa-miR-429. Taken together, the present study identified several miRNAs and potential biological mechanisms involved in the tumorigenesis of MTC. This study identified the key DEMs and potential mechanisms underlying the development of MTC, and provided a series of biomarkers and targets for the management of MTC.

MicroRNA-34 family: a potential tumor suppressor and therapeutic candidate in cancer

MicroRNA-34 (miR-34) has been reported to be dysregulated in various human cancers and regarded as a tumor suppressive microRNA because of its synergistic effect with the well-known tumor suppressor p53. Along with the application of MRX34, the first tumor-targeted microRNA drug which based on miR-34a mimics, on phase I clinical trial (NCT01829971), the significance of miR-34 is increasingly recognized. miR-34 plays a crucial role on repressing tumor progression by involving in epithelial-mesenchymal transition (EMT) via EMT- transcription factors, p53 and some important signal pathways. Not only that, numerous preclinical researches revealed the giant potential of miR-34a on cancer therapy through diversiform nano-scaled delivery systems. Here, we provide an overview about the function of miR-34 in various cancers and the mechanism of miR-34 in tumor-associated EMT. Furthermore, its potential role as a microRNA therapeutic candidate is also discussed. Notwithstanding some obstacles existed, the extensive application prospect of miR-34 on oncotherapy cannot be neglected.