Let-7a functions as a tumor suppressor in Ewing's sarcoma cell lines partly by targeting cyclin-dependent kinase 6

Development of 5-FU-modified tumor suppressor microRNAs as a platform for novel microRNA-based cancer therapeutics

MicroRNA (miRNAs) are pleiotropic post-transcriptional modulators of gene expression. Their inherently pleiotropic nature makes miRNAs strong candidates for the development of cancer therapeutics, yet despite their potential, there remains a challenge to deliver nucleic acid-based therapies into cancer cells. We developed a novel approach to modify miRNAs by replacing the uracil bases with 5-fluorouracil (5-FU) in the guide strand of tumor suppressor miRNAs, thereby combining the therapeutic effect of 5-FU with tumor-suppressive effect of miRNAs to create a potent, multi-targeted therapeutic molecule without altering its native RNAi function. To demonstrate the general applicability of this approach to other tumor-suppressive miRNAs, we screened a panel of 12 novel miRNA mimetics in several cancer types, including leukemia, breast, gastric, lung, and pancreatic cancer. Our results show that 5-FU-modified miRNA mimetics have increased potency (low nanomolar range) in inhibiting cancer cell proliferation and that these mimetics can be delivered into cancer cells without delivery vehicle both in vitro and in vivo, thus representing significant advancements in the development of therapeutic miRNAs for cancer. This work demonstrates the potential of fluoropyrimidine modifications that can be broadly applicable and may serve as a platform technology for future miRNA and nucleic acid-based therapeutics.

Let-7a suppresses Ewing sarcoma CSCs' malignant phenotype via forming a positive feedback circuit with STAT3 and lin28

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Let-7a was repressed in the cancer stem cells of Ewing sarcoma(ES-CSCs).

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Increase the expression of let-7a suppress the ability of colony formation and invasion of ES-CSCs.

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Let-7a, STAT3 and lin28 form a positive feedback circuit in ES-CSCs.

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Increase the expression of let-7a suppress xenograft tumor growth of ES-CSCs.

Cancer stem cells (CSCs) have been documented to be closely related with tumor metastasis and recurrence, and the same important role were identified in Ewing Sarcoma (ES). In our previous study, we found that let-7a expression was repressed in ES. Herein, we further identified its putative effects in the CSCs of ES (ES-CSCs). The expression of let-7a was consistently suppressed in the separated side population (SP) cells, which were identified to contain the characteristics of the stem cells. Then, we increased the expression of let-7a in ES-CSCs, and found that the ability of colony formation and invasion of ES-CSCs were suppressed in vitro. The same results were found in the tumor growth of ES-CSCs’ xenograft mice in vivo. To further explore the putative mechanism involved, we also explored whether signal transducer and activator of transcription 3 (STAT3) was involved in the suppressive effects. As expected, excessive expression of let-7a could suppress the expression STAT3 in the ES-CSCs, and repressed the expression of STAT3 imitated the suppressive effects of let-7a on ES-CSCs, suppressing the ability of colony formation and invasion of ES-CSCs. Furthermore, we found lin28 was involved in the relative impacts of let-7a, as well as STAT3. Let-7a, STAT3 and lin28 might form a positive feedback circuit, which serve a pivotal role in the carcinogensis of ES-CSCs. These findings maybe provide assistance for patients with ES in the future, especially those with metastasis and recurrence, and new directions for their treatment.

LncRNA FOXP4-AS1 Promotes Progression of Ewing Sarcoma and Is Associated With Immune Infiltrates

Ewing sarcoma (ES) is a highly malignant primary bone tumor with poor prognosis. Studies have shown that abnormal expression of lncRNA influences the prognosis of tumor patients. Herein, we established that FOXP4-AS1 was up-regulated in ES and this correlated with poor prognosis. Further analysis illustrated that FOXP4-AS1 down-regulation repression growth, migration, along with invasion of ES. On the contrary, up-regulation of FOXP4-AS1 promoted the growth, migration, as well as invasion of ES. To explore the mechanism of FOXP4-AS1, Spearman correlation analysis was carried out to determine genes that were remarkably linked to FOXP4-AS1 expression. The potential functions and pathways involving FOXP4-AS1 were identified by GO analysis, Hallmark gene set enrichment analysis, GSEA, and GSVA. The subcellular fractionation results illustrated that FOXP4-AS1 was primarily located in the cytoplasm of ES cells. Then a ceRNA network of FOXP4-AS1 was constructed. Analysis of the ceRNA network and GSEA yielded two candidate mRNAs for FOXP4-AS1. Results of the combined survival analysis led us to speculate that FOXP4-AS1 may affect the expression of TMPO by sponging miR-298, thereby regulating the malignant phenotype of ES. Finally, we found that FOXP4-AS1 may modulates the tumor immune microenvironment in an extracellular vesicle-mediated manner. In summary, FOXP4-AS1 correlates with poor prognosis of ES. It promotes the growth, migration, as well as invasion of ES cells and may modulate the tumor immune microenvironment.

Modeling the Tumor Microenvironment and Pathogenic Signaling in Bone Sarcoma

Investigations of cancer biology and screening of potential therapeutics for efficacy and safety begin in the preclinical laboratory setting. A staple of most basic research in cancer involves the use of tissue culture plates, on which immortalized cell lines are grown in monolayers. However, this practice has been in use for over six decades and does not account for vital elements of the tumor microenvironment that are thought to aid in initiation, propagation, and ultimately, metastasis of cancer. Furthermore, information gleaned from these techniques does not always translate to animal models or, more crucially, clinical trials in cancer patients. Osteosarcoma (OS) and Ewing sarcoma (ES) are the most common primary tumors of bone, but outcomes for patients with metastatic or recurrent disease have stagnated in recent decades. The unique elements of the bone tumor microenvironment have been shown to play critical roles in the pathogenesis of these tumors and thus should be incorporated in the preclinical models of these diseases. In recent years, the field of tissue engineering has leveraged techniques used in designing scaffolds for regenerative medicine to engineer preclinical tumor models that incorporate spatiotemporal control of physical and biological elements. We herein review the clinical aspects of OS and ES, critical elements present in the sarcoma microenvironment, and engineering approaches to model the bone tumor microenvironment. Impact statement The current paradigm of cancer biology investigation and therapeutic testing relies heavily on monolayer, monoculture methods developed over half a century ago. However, these methods often lack essential hallmarks of the cancer microenvironment that contribute to tumor pathogenesis. Tissue engineers incorporate scaffolds, mechanical forces, cells, and bioactive signals into biological environments to drive cell phenotype. Investigators of bone sarcomas, aggressive tumors that often rob patients of decades of life, have begun to use tissue engineering techniques to devise in vitro models for these diseases. Their efforts highlight how critical elements of the cancer microenvironment directly affect tumor signaling and pathogenesis.

Slow skeletal muscle troponin T, titin and myosin light chain 3 are candidate prognostic biomarkers for Ewing's sarcoma

Ewing's sarcoma (ES) is a common malignant bone tumor in children and adolescents. Although great efforts have been made to understand the pathogenesis and development of ES, the underlying molecular mechanism remains unclear. The present study aimed to identify new key genes as potential biomarkers for the diagnosis, targeted therapy or prognosis of ES. mRNA expression profile chip data sets GSE17674, GSE17679 and GSE45544 were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened using the R software limma package, and functional and pathway enrichment analyses were performed using the enrichplot package and GSEA software. The NetworkAnalyst online tool, as well as Cytoscape and its plug-ins cytoHubba and NetworkAnalyzer, were used to construct a protein-protein interaction network (PPI) and conduct module analysis to screen key (hub) genes. LABSO COX regression and overall survival (OS) analysis of the Hub genes were performed. A total of 211 DEGs were obtained by integrating and analyzing the three data sets. The functions and pathways of the DEGs were mainly associated with the regulation of small-molecule metabolic processes, cofactor-binding, amino acid, proteasome and ribosome biosynthesis in eukaryotes, as well as the Rac1, cell cycle and P53 signaling pathways. A total of one important module and 20 hub genes were screened from the PPI network using the Maximum Correlation Criteria algorithm of cytoHubba. LASSO COX regression results revealed that titin (TTN), fast skeletal muscle troponin T, skeletal muscle actin α-actin, nebulin, troponin C type 2 (fast), myosin light-chain 3 (MYL3), slow skeletal muscle troponin T (TNNT1), myosin-binding protein C1 slow-type, tropomyosin 3 and myosin heavy-chain 7 were associated with prognosis in patients with ES. The Kaplan-Meier curves demonstrated that high mRNA expression levels of TNNT1 (P<0.001), TTN (P=0.049), titin-cap (P=0.04), tropomodulin 1 (P=0.011), troponin I2 fast skeletal type (P=0.021) and MYL3 (P=0.017) were associated with poor OS in patients with ES. In conclusion, the DEGs identified in the present study may be key genes in the pathogenesis of ES, three of which, namely TNNT1, TTN and MYL3, may be potential prognostic biomarkers for ES.

Toosendanin induces the apoptosis of human Ewing's sarcoma cells via the mitochondrial apoptotic pathway

Toosendanin, a triterpenoid extracted from the root bark of Melia toosendan, has its origin from traditional Chinese medicine and has been used as a non‑polluting and pesticide‑free plant insecticide in China for fruit and vegetable production. In recent years, toosendanin has been found to inhibit tumor cell proliferation and promote tumor cell apoptosis. Ewing's sarcoma (ES) is the second most common primary malignant bone and soft tissue tumor in children and adolescents. Although the overall prognosis of ES has improved, the 5‑year survival rate has not significantly increased. To analyze the role of toosendanin on ES progression, CCK‑8 viability assay, flow cytometry, Hoechst 33258 staining and western blotting were performed. The present results suggested that toosendanin suppressed cell viability and induced apoptosis in human SK‑ES‑1 cells compared with DMSO treatment. In addition, in the present study, toosendanin was found to upregulate the expression of Bax and downregulate the expression of Bcl‑2, altering the Bax/Bcl‑2 ratio. Additionally, toosendanin promoted the release of cytochrome c, resulting in the activation of the mitochondrial apoptotic pathway, thus inducing the activation of caspase‑9 and caspase‑3, and the cleavage of PARP. Our results demonstrated that toosendanin inhibited the growth of ES cells in a dose‑dependent manner and triggered mitochondrial apoptotic pathway to induce apoptosis. Therefore, toosendanin can potentially be utilized as an anticancer botanical drug for the treatment of ES.

Circulating Exosomal miRNA Profile During Term and Preterm Birth Pregnancies: A Longitudinal Study

Despite decades of research in the field of human reproduction, the mechanisms responsible for human parturition still remain elusive. The objective of this study was to describe the changes in the exosomal miRNA concentrations circulating in the maternal plasma between mothers delivering term and preterm neonates, across gestation using a longitudinal study design. This descriptive study identifies the miRNA content in exosomes present in maternal plasma of term and preterm birth (PTB) (n = 20 and n = 10 per each gestational period, respectively) across gestation (i.e., first, second, and third trimesters and at the time of delivery). Changes in exosomal miRNA signature in maternal plasma during term and preterm gestation were determined using the NextSeq 500 high-output 75 cycles sequencing platform. A total of 167 and 153 miRNAs were found to significantly change (P < 0.05) as a function of the gestational age across term and PTB pregnancies, respectively. Interestingly, a comparison analysis between the exosomal miRNA profile between term and PTB reveals a total of 173 miRNAs that significantly change (P < 0.05) across gestation. Specific trends of changes (i.e., increase, decrease, and both) as a function of the gestational age were also identified. The bioinformatics analyses establish that the differences in the miRNA profile are targeting signaling pathways associated with TGF-β signaling, p53, and glucocorticoid receptor signaling, respectively. These data suggest that the miRNA content of circulating exosomes in maternal blood might represent a biomolecular "fingerprint" of the progression of pregnancy.

Diagnostic and prognostic values of blood microRNA-Let7A for osteosarcoma

OBJECTIVE

In view of the poor prognosis and difficulties in the diagnosis of osteosarcoma, and the functionality of microRNA-Let7A in different types of human cancers, our study aimed to explore the diagnostic and prognostic values of microRNA-Let7A for osteosarcoma.

METHODS

A total of 39 patients with osteosarcoma and 19 normal healthy people were included in this study. All patients received surgical resection, and tumor tissues as well as pericarcinomatous tissues were collected during surgical operation. Venous blood (2 ml) was extracted from each participant. Expression of microRNA-Let7A in tumor tissues and pericarcinomatous tissues, and expression of E2F2 and microRNA-Let7A in blood of each participant was detected by qRT-PCR. ROC analysis was performed to evaluate the diagnostic values of blood E2F2 and microRNA-Let7A for osteosarcoma, and prognostic values of microRNA-Let7A for osteosarcoma was evaluated by survival curve comparisons.

RESULTS

Expression level of microRNA-Let7A was significantly lower in tumor tissues than that in pericarcinomatous tissues. MicroRNA-Let7A expression in blood was significantly downregulated in osteosarcoma patients compared with normal control. Expression of microRNA-Let7A was negatively correlated with the expression of E2F2 in blood of osteosarcoma patients. Compared with E2F2, blood microRNA-Let7A can more effectively predict osteosarcoma. Overall survival rate of osteosarcoma patient with low blood expression level of miRNA-let-7a was significantly lower than that of patients with high blood expression level of miRNA-let-7a.

CONCLUSION

Blood microRNA-Let7A is a promising diagnostic and prognostic biomarker for osteosarcoma.

miR-124 represses the mesenchymal features and suppresses metastasis in Ewing sarcoma

Metastasis is the most powerful predictor of poor outcome of Ewing sarcoma (ES). Thus, identification of new molecules involved in tumor metastasis is of crucial importance to reduce morbidity and mortality of this devastating disease. In this study, we found that miR-124, a highly conserved miRNA, was suppressed in ES tissues and might be associated with tumor metastasis through suppressing its mesenchymal features. Overexpression of miR-124 suppressed the invasion of ES cells in vitro and tumor metastasis in vivo, which might be achieved through suppressing its mesenchymal features, as overexpression of miR-124 could repress the mesenchymal genes expression, and inhibit cell differentiation to mesenchymal lineages in ES cells. However, when SLUG was experimentally restored in these cells, mesenchymal features including suppressed expression of mesenchymal genes and decreased invasive ability were observed. We also found that cyclin D2 (CCND2) was a novel target gene of miR-124, and was directly involved in miR-124-mediated suppressive effects on cell growth. Lastly, we found that treatment with 5-Aza-CdR restored the expression of miR-124, accompanied with suppressed cell proliferation, invasion and mesenchymal features of ES cells, which demonstrated that hypermethylation might be involved in the regulation of miR-124 expression. Collectively, our data suggest that hypermethylation-mediated suppression of miR-124 might be involved in the tumor initiation and metastasis through suppressing the mesenchymal features of ES cells.

Target discovery screens using pooled shRNA libraries and next-generation sequencing: A model workflow and analytical algorithm

In the search for novel therapeutic targets, RNA interference screening has become a valuable tool. High-throughput technologies are now broadly accessible but their assay development from baseline remains resource-intensive and challenging. Focusing on this assay development process, we here describe a target discovery screen using pooled shRNA libraries and next-generation sequencing (NGS) deconvolution in a cell line model of Ewing sarcoma. In a strategy designed for comparative and synthetic lethal studies, we screened for targets specific to the A673 Ewing sarcoma cell line. Methods, results and pitfalls are described for the entire multi-step screening procedure, from lentiviral shRNA delivery to bioinformatics analysis, illustrating a complete model workflow. We demonstrate that successful studies are feasible from the first assay performance and independent of specialized screening units. Furthermore, we show that a resource-saving screen depth of 100-fold average shRNA representation can suffice to generate reproducible target hits despite heterogeneity in the derived datasets. Because statistical analysis methods are debatable for such datasets, we created ProFED, an analysis package designed to facilitate descriptive data analysis and hit calling using an aim-oriented profile filtering approach. In its versatile design, this open-source online tool provides fast and easy analysis of shRNA and other count-based datasets to complement other analytical algorithms.

Cancer Hallmarks and MicroRNAs: The Therapeutic Connection

Human cancers are characterized by a number of hallmarks, including sustained proliferative signaling, evasion of growth suppressors, activated invasion and metastasis, replicative immortality, angiogenesis, resistance to cell death, and evasion of immune destruction. As microRNAs (miRNAs) are deregulated in virtually all human cancers, they show involvement in each of the cancer hallmarks as well. In this chapter, we describe the involvement of miRNAs in cancer from a cancer hallmarks and targeted therapeutics point of view. As no miRNA-based cancer therapeutics are available to date, and the only clinical trial on miRNA-based cancer therapeutics (MRX34) was terminated prematurely due to serious adverse events, we are focusing on protein-coding miRNA targets for which targeted therapeutics in oncology are already approved by the FDA. For each of the cancer hallmarks, we selected major protein-coding players and describe the miRNAs that target them.

The roles and therapeutic potential of cyclin-dependent kinases (CDKs) in sarcoma

Uncontrolled proliferation and cell growth is the hallmark of many different malignant diseases, including sarcomas. Cyclin-dependent kinases (CDKs) are members of the serine/threonine protein kinase family and play crucial roles in tumor cell proliferation and growth by controlling cell cycle, transcription, and RNA splicing. In addition, several CDKs influence multiple targets and phosphorylate transcription factors involved in tumorigenesis. There are many examples linking dysregulated activation and expression of CDKs to tumors, and targeting CDKs in tumor cells has become a promising therapeutic strategy. More recently, the Food and Drug Administration (FDA) has approved the CDK4/6 inhibitor palbociclib for treating metastatic breast cancer. In sarcomas, high levels of CDK mRNA and protein expression have been found in most human sarcoma cells and patient tissues. Many studies have demonstrated consistent results in which inhibition of different CDKs decrease sarcoma cell growth and induce apoptosis. Therefore, CDKs comprise an attractive set of targets for novel anti-sarcoma drug development. In this review, we discuss the roles of different members of CDKs in various sarcomas and provide a pre-clinical overview of promising therapeutic potentials of targeting CDKs with a special emphasis on sarcoma.

Circulating miRNAs in Murine Experimental Endometriosis

Endometriosis is a chronic disease that commonly affects women of reproductive age; however, diagnosis is often delayed due to lack of appreciation of early signs and symptoms. Development of a noninvasive biomarker would significantly reduce delays in diagnosis and treatment. Circulating microRNAs (miRNAs) have been implicated as biomarkers for several diseases including endometriosis. Here, we use an miRNA array to investigate differential miRNA abundance in the serum of mice after induction of experimental endometriosis. let-7a-5p was decreased in the serum of mice with endometriosis. let-7b-5p, c-5p, and e-5p also showed a trend toward downregulation. Serum let-7 family miRNA shows similar dysregulation in endometriosis in both humans and mice. Diminished circulating let-7 implies a complex regulation that potentially involves multiple organs. Further investigation is necessary to determine the functional roles of let-7 miRNAs in this disease.

The association between let-7, RAS and HIF-1α in Ewing Sarcoma tumor growth

Ewing Sarcoma (ES) is the second most common primary malignant bone tumor in children and adolescents. microRNAs (miRNAs) are involved in cancer as tumor suppressors or oncogenes. We studied the involvement of miRNAs located on chromosomes 11q and 22q that participate in the most common translocation in ES. Of these, we focused on 3 that belong to the let-7 family.

We studied the expression levels of let-7a, and let-7b and detected a significant correlation between low expression of let-7b and increased risk of relapse. let-7 is known to be a negative regulator of the RAS oncogene. Indeed, we detected an inverse association between the expression of let-7 and RAS protein levels and its downstream target p-ERK, following transfection of let-7 mimics and inhibitors. Furthermore, we identified let-7 as a negative regulator of HIF-1α and EWS-FLI-1. Moreover, we were able to show that HIF-1α directly binds to the EWS-FLI-1 promoter. Salirasib treatment in-vitro resulted in the reduction of cell viability, migration ability, and in the decrease of cells in S-phase. A significant reduction in tumor burden and in the expression levels of both HIF-1α and EWS-FLI-1 proteins were observed in mice after treatment.

Our results support the hypothesis that let-7 is a tumor suppressor that negatively regulates RAS, also in ES, and that HIF-1α may contribute to the aggressive metastatic behavior of ES. Moreover, the reduction in the tumor burden in a mouse model of ES following Salirasib treatment, suggests therapeutic potential for this RAS inhibitor in ES.

Expression of CCL21 in Ewing sarcoma shows an inverse correlation with metastases and is a candidate target for immunotherapy

Ewing sarcoma is an aggressive neoplasm predominantly occurring in adolescents and has a poor prognosis when metastasized. For patients with metastatic disease in particular, immunotherapy has been proposed as possible beneficial additive therapy. CCL21 activation-based immunotherapy was successful in preclinical studies in other tumor types; therefore, we investigated CCL21 expression in Ewing sarcoma as potential target for immunotherapy. The CCL21 RNA expression was determined in 21 Ewing sarcoma cell lines and 18 primary therapy-naive Ewing sarcoma samples. In the tumor samples, this was correlated with the number and CD4⁺/CD8⁺ ratio of infiltrating T cells and clinical parameters. Higher RNA expression levels of CCL21 significantly correlated with a lower CD4⁺/CD8⁺ T cell ratio (P = 0.009), good chemotherapeutic response (P = 0.01) and improved outcome (P < 0.001). In patients with metastases, CCL21 expression was significantly lower than in patients without (P < 0.0005). CCL21 expression was significantly higher in Ewing sarcoma tissue samples compared to cell lines (P < 0.01), implying the involvement of a stromal factor. Protein expression analysis of CCL21 and its receptor CCR7 in 24 therapy-naïve tumors showed that there was no expression in all bar one Ewing sarcoma cells. In conclusion, CCL21 is expressed in clinical Ewing sarcoma samples by nontumor-infiltrating immune cells. The observed positive correlation with survival implies that CCL21 might be a potential prognostic marker for Ewing sarcoma and marks the potential of CCL21 immunotherapy for use in Ewing sarcoma.

JAK-STAT signaling in cancer: From cytokines to non-coding genome

In the past decades, studies of the Janus kinases (JAKs) and signal transducers and activators of transcription (STATs) signaling have uncovered highly conserved programs linking cytokine signaling to the regulation of essential cellular mechanisms such as proliferation, invasion, survival, inflammation and immunity. Inhibitors of the JAK/STAT pathway are used for treatment of autoimmune diseases, such as rheumatoid arthritis or psoriasis. Aberrant JAK/STAT signaling has been identified to contribute to cancer progression and metastatic development. Targeting of JAK/STAT pathway is currently one of the most promising therapeutic strategies in prostate cancer (PCa), hematopoietic malignancies and sarcomas. Notably, newly identified regulators of JAK/STAT signaling, the non-coding RNAs transcripts and their role as important targets and potential clinical biomarkers are highlighted in this review. In addition to the established role of the JAK/STAT signaling pathway in traditional cytokine signaling the non-coding RNAs add yet another layer of hidden regulation and function. Understanding the crosstalk of non-coding RNA with JAK/STAT signaling in cancer is of critical importance and may result in better patient stratification not only in terms of prognosis but also in the context of therapy.

Ewing's Sarcoma: An Analysis of miRNA Expression Profiles and Target Genes in Paraffin-Embedded Primary Tumor Tissue

The molecular mechanism responsible for Ewing’s Sarcoma (ES) remains largely unknown. MicroRNAs (miRNAs), a class of small non-coding RNAs able to regulate gene expression, are deregulated in tumors and may serve as a tool for diagnosis and prediction. However, the status of miRNAs in ES has not yet been thoroughly investigated. This study compared global miRNAs expression in paraffin-embedded tumor tissue samples from 20 ES patients, affected by primary untreated tumors, with miRNAs expressed in normal human mesenchymal stromal cells (MSCs) by microarray analysis. A miRTarBase database was used to identify the predicted target genes for differentially expressed miRNAs. The miRNAs microarray analysis revealed distinct patterns of miRNAs expression between ES samples and normal MSCs. 58 of the 954 analyzed miRNAs were significantly differentially expressed in ES samples compared to MSCs. Moreover, the qRT-PCR analysis carried out on three selected miRNAs showed that miR-181b, miR-1915 and miR-1275 were significantly aberrantly regulated, confirming the microarray results. Bio-database analysis identified BCL-2 as a bona fide target gene of the miR-21, miR-181a, miR-181b, miR-29a, miR-29b, miR-497, miR-195, miR-let-7a, miR-34a and miR-1915. Using paraffin-embedded tissues from ES patients, this study has identified several potential target miRNAs and one gene that might be considered a novel critical biomarker for ES pathogenesis.

Let-7a suppresses macrophage infiltrations and malignant phenotype of Ewing sarcoma via STAT3/NF-κB positive regulatory circuit

The interaction between tumors cells, tumor-derived humoral factors and the bone marrow in the bone niches has been shown to be essential for bone tumor initiation and promotion. Among the tumor stromal cells, tumor-associated macrophages (TAMs) are usually the most abundant immune population. Previously, we reported that let-7a functions as a tumor suppressor in ES. Herein, we found that the suppressive effects are not only limited on the malignant phenotype of tumor cells but also on the regulation of macrophage infiltration. We observed that the let-7a expression is negatively related to macrophage infiltrations in ES. Moreover, overexpression of putative ts-miRNA let-7a significantly suppressed the recruitment of PBMCs in vitro and decreased the macrophage infiltrations in ES-xenografted tumors in vivo. Most importantly, a positive regulatory feedback loop consisting of let-7a, signal transducer and activator of transcription 3 (STAT3), and nuclear factor-kappa B (NF-κB) (let-7a/STAT3/NF-κB) was involved in let-7a-mediated suppressive effects. These data might provide evidence of a novel intracellular signaling network function in ES pathogenesis, and manipulating this novel feedback loop will have therapeutic potential for ES patients.

Genetic and epigenetic alterations of microRNAs and implications for human cancers and other diseases

MicroRNAs (miRNAs) are a well-studied group of noncoding RNAs that control gene expression by interacting mainly with messenger RNA. It is known that miRNAs and their biogenesis regulatory machineries have crucial roles in multiple cell processes; thus, alterations in these genes often lead to disease, such as cancer. Disruption of these genes can occur through epigenetic and genetic alterations, resulting in aberrant expression of miRNAs and subsequently of their target genes. This review focuses on the disruption of miRNAs and their key regulatory machineries by genetic alterations, with emphasis on mutations and epigenetic changes in cancer and other diseases.

MicroRNAs in the pathobiology of sarcomas

Sarcomas are a rare and heterogeneous group of tumors. The last decade has witnessed extensive efforts to understand the pathobiology of many aggressive sarcoma types. In parallel, we have also begun to unravel the complex gene regulation processes mediated by microRNAs (miRNAs) in sarcomas and other cancers, discovering that microRNAs have critical roles in the majority of both oncogenic and tumor suppressor signaling networks. Expression profiles and a greater understanding of the biologic roles of microRNAs and other noncoding RNAs have considerably expanded our current knowledge and provided key pathobiological insights into many sarcomas, and helped identify novel therapeutic targets. The limited number of sarcoma patients in each sarcoma type and their heterogeneity pose distinct challenges in translating this knowledge into the clinic. It will be critical to prioritize these novel targets and choose those that have a broad applicability. A small group of microRNAs have conserved roles across many types of sarcomas and other cancers. Therapies that target these key microRNA-gene signaling and regulatory networks, in combination with standard of care treatment, may be the pivotal component in significantly improving treatment outcomes in patients with sarcoma or other cancers.

What Do We Know about the Role of miRNAs in Pediatric Sarcoma?

Non-coding RNAs have received a lot of attention in recent years, with especial focus on microRNAs (miRNAs), so much so that in the just over two decades since the first miRNA, Lin4, was described, almost 40,000 publications about miRNAs have been generated. Less than 500 of these focus on sarcoma, and only a fraction of those on sarcomas of childhood specifically, with some of these representing observational studies and others containing functionally validated data. This is a group of cancers for which prognosis is often poor and therapeutic options limited, and it is especially in these areas that strides in understanding the role of non-coding RNAs and miRNAs in particular are to be welcomed. This review deals with the main forms of pediatric sarcoma, exploring what is known about the diagnostic and prognostic profiles of miRNAs in these tumours and where novel therapeutic options might present themselves for further exploration.

Overexpression of miR‑199b‑5p inhibits Ewing's sarcoma cell lines by targeting CCNL1

MicroRNAs (miRNAs) are known to regulate the expression of a variety of genes, which are important in the development of several types of tumor, including Ewing's sarcoma (ES), at the post‑transcriptional level. Although previous studies have identified that the expression of miRNA‑199b‑5p was downregulated in various types of tumor, the expression levels of miR‑199b‑5p in ES cells remain to be elucidated. The mechanism underlying ES via the miRNA pathway remains to be elucidated. The present study demonstrated that miR‑199b‑5p was an important regulator in ES cells and its expression was downregulated in ES originated A673/TC252 cells. The ES cell lines, A673 and TC252, were transfected with an miR‑199b‑5p mimic to overexpress the levels of this miRNA. This forced expression of miR‑199b‑5p suppressed the cell proliferation and invasion, arrested cell cycle progression, and promoted cell apoptosis. Furthermore, CCNL1 was identified by bioinformatic software as a potential target gene of miR‑199b‑5p. Following this, the present study identified CCNL1 as a direct target of miR‑199b‑5p in ES cells. Taken together, the present study established a functional link between ES, miR‑199b‑5p and CCNL1, and suggested that miR‑199b‑5p acts as a tumor suppressor and may be of diagnostic and therapeutic importance for human ES.

ASK1 modulates the expression of microRNA Let7A in microglia under high glucose in vitro condition

Hyperglycemia results in oxidative stress and leads to neuronal apoptosis in the brain. Diabetes studies show that microglia participate in the progression of neuropathogenesis through their involvement in inflammation in vivo and in vitro. In high-glucose-induced inflammation, apoptosis signal regulating kinase 1 (ASK1) triggers the release of apoptosis cytokines and apoptotic gene expression. MicroRNA-Let7A (miR-Let7A) is reported to be a regulator of inflammation. In the present study, we investigated whether miR-Let7A regulates the function of microglia by controlling ASK1 in response to high-glucose-induced oxidative stress. We performed reverse transcription (RT) polymerase chain reaction, Taqman assay, real-time polymerase chain reaction, and immunocytochemistry to confirm the alteration of microglia function. Our results show that miR-Let7A is associated with the activation of ASK1 and the expression of anti-inflammatory cytokine (interleukin (IL)-10) and Mycs (c-Myc and N-Myc). Thus, the relationship between Let-7A and ASK1 could be a novel target for enhancing the beneficial function of microglia in central nervous system (CNS) disorders.

Let7a involves in neural stem cell differentiation relating with TLX level

Neural stem cells (NSCs) have the potential for differentiation into neurons known as a groundbreaking therapeutic solution for central nervous system (CNS) diseases. To resolve the therapeutic efficiency of NSCs, recent researchers have focused on the study on microRNA's role in CNS. Some micro RNAs have been reported significant functions in NSC self-renewal and differentiation through the post-transcriptional regulation of neurogenesis genes. MicroRNA-Let7a (Let7a) has known as the regulator of diverse cellular mechanisms including cell differentiation and proliferation. In present study, we investigated whether Let7a regulates NSC differentiation by targeting the nuclear receptor TLX, which is an essential regulator of NSC self-renewal, proliferation and differentiation. We performed the following experiments: western blot analysis, TaqMan assay, RT-PCR, and immunocytochemistry to confirm the alteration of NSCs. Our data showed that let7a play important roles in controlling NSC fate determination. Thus, manipulating Let-7A and TLX could be a novel strategy to enhance the efficiency of NSC's neuronal differentiation for CNS disorders.

Expression of cdk6 in head and neck squamous cell carcinoma

OBJECTIVE

Cdk6 is a key regulator during the G1/S cell cycle transition. Aberrant expression of cdk6 protein has been observed in many cancer types. However, little is known about the expression of cdk6 in head and neck squamous cell carcinoma (HNSCC) and its clinical significance. This study evaluated the expression of cdk6 in HNSCC and analyzed the relationship between cdk6 expression and clinicopathological parameters of HNSCC.

MATERIALS AND METHODS

Expression of cdk6 was immunohistochemically investigated in 98 HNSCCs. Nuclear and cytoplasmic positive cells were counted separately. Data were presented as the percentage of positive cells. The correlation between the percentage of positive cells and clinicopathological factors was determined.

RESULTS

Nuclear and cytoplasmic staining for cdk6 were detected in 91 cases and 97 cases, respectively. A significant correlation was found only between the percentage of nuclear positive cells and T classification (p value = 0.0410). Tumors with high nuclear cdk6-positive cells showed a linear trend toward advanced tumor status (p value = 0.0064).

CONCLUSIONS

Cdk6 was highly expressed in HNSCC. Tumors with high nuclear cdk6 expression tended to have advanced tumor status. These results suggest that cdk6 plays a vital role in HNSCC and is involved in tumor progression of this cancer.

CLINICAL RELEVANCE

An increased nuclear cdk6 expression is an unfavorable factor for HNSCC. Cdk6 may serve as a therapeutic target in this cancer.

DNA/RNA chimera templates improve the emission intensity and target the accessibility of silver nanocluster-based sensors for human microRNA detection

In recent years microRNAs (miRNAs) have been established as important biomarkers in a variety of diseases including cancer, diabetes, cardiovascular disease, aging, Alzheimer's disease, asthma, autoimmune disease and liver diseases. As a consequence, a variety of monitoring methods for miRNAs have been developed, including a fast and simple method for miRNA detection by exploitation of the unique photoluminescence of DNA-templated silver nanoclusters (DNA/AgNCs). To increase the versatility of the AgNC-based method, we have adopted DNA/RNA chimera templates for AgNC-based probes, allowing response from several human miRNAs which are hardly detectable with DNA-based probes. Here, we demonstrate in detail the power of DNA/RNA chimera/AgNC probes in detecting two human miRNAs, let-7a and miR-200c. The DNA/RNA chimera-based probes are highly efficient to determine the level of miRNAs in several human cell lines.

miR-211 suppresses epithelial ovarian cancer proliferation and cell-cycle progression by targeting Cyclin D1 and CDK6

BACKGROUND

Epithelial ovarian cancer (EOC) is a significant cause of morbidity and mortality. MicroRNAs play important roles in cancer development and progression. The microRNA miR-211 is localized on intron 6 of the Trpm1 gene at 15q13-q14, a locus that is frequently lost in neoplasms. Its function and loss-of-function have been described in normal and cancer cells and tissues. miR-211 is known to be dysregulated in ovarian cancer: however, its function and the downstream effect of its loss-of-function in ovarian cancer have not been described before.

METHODS

We analyzed miR-211 expression in clinical samples of primary EOC tissues compared to normal epithelial ovarian tissues and in the EOC cell lines: OVCAR3, Caov3, OVCA429, SKOV3 and A2780 compared to human ovarian surface epithelial cells. We then investigated the effect of miR-211 on EOC cell proliferation and apoptosis by counting cell numbers, MTT, colony formation, cell cycle, and PI/Annexin V staining assays. A luciferase reporter system was developed to assess miR-211 regulation of the predicted targets. Expression level of discovered targets and correlation with miR-211 expression were analyzed in EOC tissues. Finally, OVCAR3 stably expressing miR-211 or control cells were injected subcutaneously into mice to determine in vivo effect of miR-211 on tumorigenesis.

RESULTS

We found that the expression of miR-211 is downregulated in EOC tissues and cell lines compared to normal epithelial ovarian tissue and human ovarian surface epithelial cells, respectively. miR-211 was found to arrest cells in the G0/G1-phase, inhibit proliferation and induce apoptosis. Cyclin D1 and CDK6 were found to be direct targets of miR-211, and when overexpressed in miR-211-expressing EOC cells, could restore proliferative ability. Finally, in vitro investigation confirmed that miR-211 is a tumor suppressor that controls Cyclin D1 and CDK6 expression.

CONCLUSIONS

Our results demonstrate that miR-211 is a tumor suppressor that controls expression of Cyclin D1 and CDK6, and that its downregulation results in overexpression of Cyclin D1 and CDK6 which increases proliferation ability of EOC cells to proliferate compared to normal cells.

MicroRNA expression and its clinical implications in Ewing's sarcoma

Ewing's sarcoma (EWS) is the second most common primary bone cancer, and is a predominant childhood malignant disease. Due to limited understanding of its pathogenesis and frequent occurrence of resistance to conventional types of treatment, its management remains difficult, and mortality is frequent. Development of EWS is a multistep process involving genetic and epigenetic alterations of protein-coding proto-oncogenes and tumour-suppressor genes. MicroRNAs (miRNAs) have recently been discovered as a new category of non-protein coding; small RNA molecules that regulate gene expression at the post-transcriptional level. Substantial numbers of deregulated miRNAs have been documented in EWS and their biological significance has been confirmed in multiple functional experiments. Several studies have confirmed involvement of miRNAs in various steps of EWS pathogenesis, from occurrence to metastasis. Functionally, miRNA dysregulation may promote cell-cycle progression, confer resistance to apoptosis, and enhance invasiveness and metastasis. These miRNAs have opened a novel field in cancer research with potential clinical utilization for screening, diagnosis, prognostics and prediction of response to treatment. Elucidating biological aspects of miRNA dysregulation may help better understand pathogenesis of EWS and promote development of miRNA directed-therapeutics against it.

MicroRNA-320c inhibits tumorous behaviors of bladder cancer by targeting Cyclin-dependent kinase 6

Background

Increasing evidence has suggested that dysregulation of microRNAs (miRNAs) could contribute to human disease including cancer. Previous miRNA microarray analysis illustrated that miR-320c is down-regulated in various cancers. However, the roles of miR-320c in human bladder cancer have not been well elucidated. Therefore, this study was performed to investigate the biological functions and molecular mechanisms of miR-320c in human bladder cancer cell lines, discussing whether it could be a therapeutic biomarker of bladder cancer in the future.

Methods

Two human bladder cancer cell lines and samples from thirteen patients with bladder cancer were analyzed for the expression of miR-320c by quantitative RT-PCR. Over-expression of miR-320c was established by transfecting mimics into T24 and UM-UC-3. Cell proliferation and cell cycle were assessed by cell viability assay, flow cytometry and colony formation assay. Cell motility ability was evaluated by transwell assay. The target gene of miR-320c was determined by luciferase assay, quantitative RT-PCR and western blot. The regulation of cell cycle and mobility by miR-320c was analyzed by western blot.

Results

We observed that miR-320c was down-regulated in human bladder cancer tissues and bladder cancer cell lines T24 and UM-UC-3. Over-expression of miR-320c could induce G1 phase arrest in UM-UC-3 and T24 cells, and subsequently inhibited cell growth. We also indentified miR-320c could impair UM-UC-3 and T24 cell motility. In addition, we identified CDK6, a cell cycle regulator, as a novel target of miR-320c. Moreover, we demonstrated miR-320c could induce bladder cancer cell cycle arrest and mobility via regulating CDK6. We also observed that inhibition of miR-320c or restoration of CDK6 in miR-320c-over-expressed bladder cancer cells partly reversed the suppressive effects of miR-320c.

Conclusions

miR-320c could inhibit the proliferation, migration and invasion of bladder cancer cells via regulating CDK6. Our study revealed that miR-320c could be a therapeutic biomarker of bladder cancer in the future.