Emerging roles of non‐coding RNAs in scoliosis

Scoliosis, a complex three‐dimensional deformity of the spine with the Cobb angle (a measure of the spinal lateral curvature) >10 degree, encompasses a spectrum of pathologies, including congenital, idiopathic, syndromic and neuromuscular aetiologies. The pathogenesis is multifactorial involving both environmental and genetic factors but the exact cellular and molecular mechanisms of disease development remain largely unknown. Emerging evidence showed that non‐coding RNAs (ncRNAs), namely microRNAs, long ncRNAs and circular RNAs, are deregulated in many orthopaedic diseases, including scoliosis. Importantly, these deregulated ncRNAs functionally participate in the initiation and progression of scoliosis. Here, we review recent progress in ncRNA research on scoliosis.     

miR‐10b expression in breast cancer stem cells supports self‐renewal through negative PTEN regulation and sustained AKT activation

Cancer stem cells (CSCs) are linked to metastasis. Moreover, a discrete group of miRNAs (metastamiRs) has been shown to promote metastasis. Accordingly, we propose that miRNAs that function as metastatic promoters may influence the CSC phenotype. To study this issue, we compared the expression of 353 miRNAs in CSCs enriched from breast cancer cell lines using qRT–PCR analysis. One of the most altered miRNAs was miR‐10b, which is a reported promoter of metastasis and migration. Stable overexpression of miR‐10b in MCF‐7 cells (miR‐10b‐OE cells) promoted higher self‐renewal and expression of stemness and epithelial–mesenchymal transition (EMT) markers. In agreement with these results, inhibiting miR‐10b expression using synthetic antisense RNAs resulted in a decrease in CSCs self‐renewal. Bioinformatics analyses identified several potential miR‐10b mRNA targets, including phosphatase and tensin homolog (PTEN), a key regulator of the PI3K/AKT pathway involved in metastasis, cell survival, and self‐renewal. The targeting of PTEN by miR‐10b was confirmed using a luciferase reporter, qRT–PCR, and Western blot analyses. Lower PTEN levels were observed in CSCs, and miR‐10b depletion not only increased PTEN mRNA and protein expression but also decreased the activity of AKT, a downstream PTEN target kinase. Correspondingly, PTEN knockdown increased stem cell markers, whereas AKT inhibitors compromised the self‐renewal ability of CSCs and breast cancer cell lines overexpressing miR‐10b. In conclusion, miR‐10b regulates the self‐renewal of the breast CSC phenotype by inhibiting PTEN and maintaining AKT pathway activation.     

MicroRNA Let‐7 targets the ecdysone signaling pathway E75 gene to control larval–pupal development in Bactrocera dorsalis

MicroRNAs (miRNAs) regulate various biological processes during insect developme nt;however, their role in larval-pupal development in oriental fruit fly, Bactrocera dorsalis (Hendel) remains unknown. In the current study, we address the biological function of a conserved miRNA, Bdo-Let-7 in the regulation of BdE75 gene, which belongs to the ecdysone signaling pathway and participates in the larval-pupal development in B. dorsalis. Using dual luciferase reporter assay in HEK293T cells we show that Bdo-Let-7 miRNA interacts with the 3' untranslated region of BdE75 gene and suppresses its expression. The Bdo-Let?7 and BdE75 are also co-expressed in the larval-pupal stages and in different tissues of B. dorsalis .In in vivo experiments, the injectio n of Bdo-Let-7 agomir and antagomir in third instar larvae down- and up-regulated the expression of BdE75、 respectively. The 20-hydroxyecdysone (20E) injection assay shows that 20E up-regulated the expression of Bdo-Let-7 on the 5th day of the larvae. Moreover, abnormal pupation and eclosion were observed after larval Bdo-Let-7 antagomir injection. Based on these results, we show that Bdo-Let-7 regulates the ecdysone signaling pathway through the exact dose of BdE75 gene, and is indispensable for normal larval-pupal development in B. dorsalis.     

FBXW7 suppresses epithelial‐mesenchymal transition and chemo‐resistance of non‐small‐cell lung cancer cells by targeting snai1 for ubiquitin‐dependent degradation

Objectives

FBXW7 acts as a tumour suppressor by targeting at various oncoproteins for ubiquitin‐mediated degradation. However, the clinical significance and the involving regulatory mechanisms of FBXW7 manipulation of NSCLC regeneration and therapy response are not clear.

Materials and Methods

Immunohistochemical staining and qRT‐PCR were applied to detect FBXW7 and Snai1 expression in 100 samples of NSCLC and matched tumour‐adjacent tissues. FBXW7 manipulation of cancer biological functions were studied by using MTT assay, immunoblotting, flow cytometry, transwells, wound healing assay, and sphere‐formation assays. Immunofluorescence and co‐immunoprecipitation were used to analyse the possible interaction between Snai1 and FBXW7.

Results

We detected the decreased FBXW7 expression in majority of the NSCLC tissues, and lower FBXW7 level was correlated with advanced TNM stage. Furthermore, those patients with decreased FBXW7 expression tend to have both poorer 5‐year survival outcomes, and shorter disease‐free survival, comparing to those with higher FBXW7 levels. Functionally, we found that FBXW7 enforcement suppressed NSCLC progression by inducing cell growth arrest, increasing chemo‐sensitivity and inhibiting Epithelial‐mesenchymal Transition (EMT) progress. Results further showed that FBXW7 could interact with Snai1 directly to degrade its expression through ubiquitylating alternation in NSCLC, which could be partially abrogated by restoring Snai1 expression.

Conclusions

FBXW7 conduction of tumour suppression was partly through degrading Snai1 directly for ubiquitylating regulation in NSCLC

     

Long non‐coding RNAs in brain tumours: Focus on recent epigenetic findings in glioma

Glioma biology is a major focus in tumour research, primarily due to the aggressiveness and high mortality rate of its most aggressive form, glioblastoma. Progress in understanding the molecular mechanisms behind poor prognosis of glioblastoma, regardless of treatment approaches, has changed the classification of brain tumours after nearly 100 years of relying on anatomopathological criteria. Expanding knowledge in genetic, epigenetic and translational medicine is also beginning to contribute to further elucidating molecular dysregulation in glioma. Long non‐coding RNAs (lncRNAs) and their main representatives, large intergenic non‐coding RNAs (lincRNAs), have recently been under scrutiny in glioma research, revealing novel mechanisms of pathogenesis and reinforcing others. Among those confirmed was the reactivation of events significant for foetal brain development and neuronal commitment. Novel mechanisms of tumour suppression and activation of stem‐like behaviour in tumour cells have also been examined. Interestingly, these processes involve lncRNAs that are present both during normal brain development and in brain malignancies and their reactivation might be explained by epigenetic mechanisms, which we discuss in detail in the present review. In addition, the review discusses the lncRNAs‐induced changes, as well as epigenetic changes that are consequential for tumour formation, affecting, in turn, the expression of various types of lncRNAs.     

Exosome biogenesis,secretion and function of exosomal miRNAs in skeletal muscle myogenesis

Exosomes are membrane‐bound extracellular vesicles that are produced in the endosomal compartment of most mammalian cell types and then released. Exosomes are effective carriers for the intercellular material transfer of material that can influence a series of physiological and pathological processes in recipient cells. Among loaded cargoes, non‐coding RNAs (ncRNAs) vary for the exosome‐producing cell and its homeostatic state, and characterization of the biogenesis and secretion of exosomal ncRNAs and the functions of these ncRNAs in skeletal muscle myogenesis remain preliminary. In this review, we will describe what is currently known of exosome biogenesis, release and uptake of exosomal ncRNAs, as well as the varied functions of exosomal miRNAs in skeletal muscle myogenesis.     

DICER1 regulated let‐7 expression levels in p53‐induced cancer repression requires cyclin D1

Let‐7 miRNAs act as tumour suppressors by directly binding to the 3′UTRs of downstream gene products. The regulatory role of let‐7 in downstream gene expression has gained much interest in the cancer research community, as it controls multiple biological functions and determines cell fates. For example, one target of the let‐7 family is cyclin D1, which promotes G0/S cell cycle progression and oncogenesis, was correlated with endoribonuclease DICER1, another target of let‐7. Down‐regulated let‐7 has been identified in many types of tumours, suggesting a feedback loop may exist between let‐7 and cyclin D1. A potential player in the proposed feedback relationship is Dicer, a central regulator of miRNA expression through sequence‐specific silencing. We first identified that DICER1 is the key downstream gene for cyclin D1‐induced let‐7 expression. In addition, we found that let‐7 miRNAs expression decreased because of the p53‐induced cell death response, with deregulated cyclin D1. Our results also showed that cyclin D1 is required for Nutlin‐3 and TAX‐induced let‐7 expression in cancer repression and the cell death response. For the first time, we provide evidence that let‐7 and cyclin D1 form a feedback loop in regulating therapy response of cancer cells and cancer stem cells, and importantly, that alteration of let‐7 expression, mainly caused by cyclin D1, is a sensitive indicator for better chemotherapies response.     

LIN28B regulates androgen receptor in human trophoblast cells through Let‐7c

LIN28B is an RNA‐binding protein necessary for maintaining pluripotency in stem cells and plays an important role in trophoblast cell differentiation. LIN28B action on target gene function often involves the Let‐7 miRNA family. Previous work in cancer cells revealed that LIN28 through Let‐7 miRNA regulates expression of androgen receptor (AR). Considering the similarities between cancer and trophoblast cells, we hypothesize that LIN28B also is necessary for the presence of AR in human trophoblast cells. The human first‐trimester trophoblast cell line, ACH‐3P was used to evaluate the regulation of AR by LIN28B, and a LIN28B knockdown cell line was constructed using lentiviral‐based vectors. LIN28B knockdown in ACH‐3P cells resulted in significantly decreased levels of AR and increased levels of Let‐7 miRNAs. Moreover, treatment of ACH‐3P cells with Let‐7c mimic, but not Let‐7e or Let‐7f, resulted in a significant reduction in LIN28B and AR. Finally, forskolin‐induced syncytialization and Let‐7c treatment both resulted in increased expression of syncytiotrophoblast marker ERVW‐1 and a significant decrease in AR in ACH‐3P. These data reveal that LIN28B regulates AR levels in trophoblast cells likely through its inhibitory actions on let‐7c, which may be necessary for trophoblast cell differentiation into the syncytiotrophoblast.