miR-20a promotes proliferation and invasion by targeting APP in human ovarian cancer cells

The role of microRNAs in neurobiology and pathophysiology of the hippocampus

MicroRNAs (miRNAs) are short non-coding and well-conserved RNAs that are linked to many aspects of development and disorders. MicroRNAs control the expression of genes related to different biological processes and play a prominent role in the harmonious expression of many genes. During neural development of the central nervous system, miRNAs are regulated in time and space. In the mature brain, the dynamic expression of miRNAs continues, highlighting their functional importance in neurons. The hippocampus, as one of the crucial brain structures, is a key component of major functional connections in brain. Gene expression abnormalities in the hippocampus lead to disturbance in neurogenesis, neural maturation and synaptic formation. These disturbances are at the root of several neurological disorders and behavioral deficits, including Alzheimer's disease, epilepsy and schizophrenia. There is strong evidence that abnormalities in miRNAs are contributed in neurodegenerative mechanisms in the hippocampus through imbalanced activity of ion channels, neuronal excitability, synaptic plasticity and neuronal apoptosis. Some miRNAs affect oxidative stress, inflammation, neural differentiation, migration and neurogenesis in the hippocampus. Furthermore, major signaling cascades in neurodegeneration, such as NF-Kβ signaling, PI3/Akt signaling and Notch pathway, are closely modulated by miRNAs. These observations, suggest that microRNAs are significant regulators in the complicated network of gene regulation in the hippocampus. In the current review, we focus on the miRNA functional role in the progression of normal development and neurogenesis of the hippocampus. We also consider how miRNAs in the hippocampus are crucial for gene expression mechanisms in pathophysiological pathways.

MicroRNAs in the pathophysiology of Alzheimer's disease and Parkinson's disease: an overview

Neurodegenerative diseases are characterized by a progressive loss of neurons of the central nervous system (CNS) and serve as a major cause of morbidity, mortality and functional dependence especially among the elderly. Despite extensive research and development efforts, the success rate of clinical pipelines has been very limited. However, microRNAs (miRs) have been proved to be of crucial importance in regulating intracellular pathways for various pathologic conditions including those of a neurodegenerative nature. There is ample evidence of altered levels of various miRs in clinical samples of Alzheimer's disease and Parkinson's disease patients with potentially major clinical implications. In the current review, we aim to summarize the relevant literature on the role of miRs in the pathophysiology of Alzheimer's disease (AD) and Parkinson's disease (PD) as the two globally predominant neurodegenerative conditions.

Differential Molecular Expression Patterns Associated with Metastasis in Cutaneous Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

The majority of cutaneous squamous cell carcinomas are treated by surgical removal; however, approximately 4% of tumors will metastasize. Molecular expression testing may improve accuracy in estimating the prognosis and defining the mechanisms important in the disease progression, which may impact response to therapy. Using PubMed (MEDLINE) and EMBASE, a systematic review was performed to evaluate studies published from January 2005 to August 2019 reporting tumor protein or RNA expression along with either outcomes (metastasis or death) or a comparison of primary with metastatic tumor samples. Inclusion criteria were met by 45 studies containing 81 comparisons of 44 distinct proteins and 25 microRNAs. On meta-analysis of studies analyzing primary tumor samples in terms of later outcomes, high primary tumor expression of PD-L1 (OR = 2.34, 95% confidence interval = 1.09-5.02, P = 0.030), EGFR (OR = 2.57, 95% confidence interval = 1.24-5.33, P = 0.011), and podoplanin (OR = 2.33, 95% confidence interval = 1.00-5.41, P = 0.049) conferred increased odds for metastasis. In comparison, metastatic tissue was more likely to have a high expression of PD-L1 than primary tissue (OR = 3.13, 95% confidence interval = 1.00-9.75, P = 0.049). Further studies are needed to confirm whether testing for PD-L1, EGFR, and podoplanin expression aids in cutaneous squamous cell carcinomas prognostic estimation of metastasis or death or predicts response to therapy.

DHA Abolishes the Detrimental Effect of Docetaxel on Downregulation of the MICA via Decreasing the Expression Level of MicroRNA-20a in Gastric Cancer

BACKGROUND

MHC class I chain-related protein A (MICA) is a membrane glycoprotein expressed abnormally on some malignant cells including gastric cancer (GC) cell and elicits anti-tumor immune responses. Downregulation of MICA expression could lead to immune-evasion of cancer cells.

OBJECTIVE(S)

In this study, we aimed to investigate the effect of docosahexaenoic acid (DHA) and docetaxel alone or in combination on the expression level of MICA and its regulating microRNA (miRNA), miR-20a in MKN45 GC cell line.

METHOD(S)

MKN45 GC cell line was cultured and MTT assay was performed to determine IC50 of docetaxel. Cells were treated by 18.5 μM docetaxel and 100 μM DHA. After that, RNA extraction and cDNA synthesis were done and the expression level of MICA and miR-20a were determined by quantitative real-time PCR for both treated and untreated cell lines.

RESULTS

Our findings showed less downregulation of the expression level of MICA by the combination of docetaxel/DHA (5.34-fold) compared with docetaxel (45.45-fold) and DHA (55.55-fold). Consistently, combination therapy led to the more downregulation of the expression level of the miR-20a (5.20-fold) in comparison to docetaxel (2.38-fold) and DHA (1.60-fold).

CONCLUSION(S)

As an unwanted effect of docetaxel therapy in GC, downregulation of MICA expression could lead to weak anti-tumor immune responses. By increasing the expression level of MICA, combination therapy of docetaxel with DHA would be useful to overcome this side effect.

NNT-AS1 modulates prostate cancer cell proliferation, apoptosis and migration through miR-496/DDIT4 axis

Background

Emerging studies have disclosed long non-coding RNAs (lncRNAs) as pivotal modulators in the progression of prostate cancer (PCa). Current research planned to figure out the involvement of lncRNA nicotinamide nucleotide transhydrogenase antisense RNA 1 (NNT-AS1) in PCa.

Methods

RNA expression was examined using RT-qPCR in PCa cells. Functional assays assessed the viability, proliferation, apoptosis and migration of PCa cells. RNA pull down and luciferase reporter experiments detected the interplay between miRNA and lncRNA or mRNA.

Results

NNT-AS1 was apparently upregulated in PCa cells. NNT-AS1 deficiency abrogated PCa cell viability, proliferation and migration but promoted apoptosis. Besides, miR-496 could be sequestered by NNT-AS1 to elevate the expression of DNA damage inducible transcript 4 (DDIT4) in PCa. Rescue assays indicated that overexpressed DDIT4 or restrained miR-496 could reverse the influence of NNT-AS1 depletion on malignant processes in PCa cells.

Conclusion

NNT-AS1 contributes to the malignant phenotypes of PCa cells through targeting miR-496 to boost DDIT4 expression.

miR-20a/Foxj2 Axis Mediates Growth and Metastasis of Colorectal Cancer Cells as Identified by Integrated Analysis

BACKGROUND MicroRNAs (miRNAs) have a significant regulatory effect on the proliferation, migration, and invasion of cells, and have been widely reported to have oncogenic or tumor-suppressive impacts on various tumors. In the present study we assessed the regulation and function of miR-20a on colorectal cancer (CRC) cell lines. MATERIAL AND METHODS qPCR was used to quantify miR-20a expression. Luciferase reporter assay was conducted to confirm Foxj2 3'UTR associations. In addition, the function of miR-20a and Foxj2 in CRC was detected using MTT, colony formation, transwell assays, and cell cycle analysis. RESULTS Our data revealed that miR-20a expression was elevated in the CRC cell lines, and cell migration, proliferation, and invasion abilities were promoted by the overexpression of miR-20a. Moreover, Foxj2 was authenticated as a direct target gene of miR-20a in CRC cells. Furthermore, we found that the ectopic Foxj2 dramatically suppressed miR-20a-promoted proliferation, migration, invasion, and xenografts in vitro and in vivo, and induced cell cycle arrest at G1 stage. CONCLUSIONS Our results showing the roles of miR-20a/Foxj2 in carcinogenesis of CRC may help improve treatment of CRC.

CADM1 inhibits ovarian cancer cell proliferation and migration by potentially regulating the PI3K/Akt/mTOR pathway

Previous studies have shown that cell adhesion molecule 1 (CADM1), an immunoglobulin superfamily member, is frequently inactivated but functions as a tumor suppressor in many solid tumors. However, the characterization of CADM1 expression in ovarian cancer cells and the mechanisms of its tumor suppressor function are not fully understood. We generated ovarian cancer cell lines in which CADM1 was stably upregulated or downregulated. CADM1 expression was significantly decreased in ovarian cancer tissue and cells lines. Functionally, knockdown of CADM1 promoted the growth, migration and invasion of ovarian cancer cells. Conversely, further experimental evidence indicated that overexpression of CADM1 inhibited the migration and invasion of ovarian cancer cells potentially through inhibition of the PI3K/Akt/mTOR signaling pathway by regulating upstream regulators (LXR/RXR, IGF1, IFI44L and C4BPA) and downstream effectors (APP, EDN1, TGFBI and Rap1A). In conclusion, CADM1 inhibits ovarian cancer cell proliferation and migration by potentially regulating the PI3K/Akt/mTOR signaling pathway. CADM1 could be a potential therapeutic target for ovarian cancer.

Amyloid precursor protein and its phosphorylated form in non-small cell lung carcinoma

Amyloid precursor protein (APP) is a well-known to be involved in the development of Alzheimer's disease and harbors several phosphorylation sites in its cytoplasmic domain. APP has been also proposed as one of the molecules involved in cell proliferation and invasion in several human malignancies. However, the roles of APP including its phosphorylated form (p-APP) have remained largely unexplored in non-small cell lung carcinoma (NSCLC). Therefore, in this study, we first examined both APP and p-APP expressions and then explored the association between p-APP/APP status and clicopathological parameters in NSCLC. The number of APP-positive cases was 24/91 (26%) in adenocarcinomas (Ad) and 16/35 (46%) in squamous cell carcinomas (Sq), respectively. p-APP-positive cases in Ad and Sq were 28 (31%) and 17 (49%), respectively. In Ad cases, both APP and p-APP were significantly associated with clinical stages (APP and p-APP), pathologic T (p-APP), and pathologic N (APP and p-APP) of the cases examined. In Sq cases, there were no significant associations between APP status and any of the clinicopathological parameters examined with an exception of the significant correlation of p-APP with lymphatic invasion. APP status was not significantly associated with overall survival (OS) of Ad patients but a significant association was detected between p-APP-positive cases and OS of these patients (p < 0.0001). In Sq cases, both APP- (p = 0.01) and p-APP-positive (p = 0.04) groups were also significantly associated with adverse clinical outcome. These results did firstly demonstrate that APP, in particular, p-APP, is considered a potent prognostic factor for both Ad and Sq lung carcinoma patients. However, APP signaling including its phosphorylation signal are considered different between these two types of NSCC cells and further investigations are required for clarification.

Associations of serum microRNA-20a, -27a, and -103a with cognitive function in a Japanese population: The Yakumo study

OBJECTIVES

MicroRNAs (miRNAs) dysregulate gene expression by binding to target messenger RNAs, and play an important role in the pathogenesis of various diseases, including cancers, cardiovascular diseases and diabetes. Circulating miRNAs have increasingly been recognized as biomarkers for detecting and diagnosing those diseases. Few studies have investigated the association of circulating miRNA with the early stages of cognitive impairment, such as mild cognitive impairment, in the general population. The purpose of this study was to examine the association between cognitive function and several serum miRNAs levels related to amyloid precursor protein (APP) proteolysis in a Japanese general population who had never been diagnosed with dementia.

METHODS

We conducted a cross-sectional study of 337 Japanese subjects (144 men, 193 women) who attended a health examination. The short form of the Mini-Mental State Examination (SMMSE) was used to assess cognitive function. Serum levels of 6 miRNAs (let-7d, miR-17, miR-20a, miR-27a, miR-34a, miR-103a) were measured by quantitative real-time polymerase chain reaction.

RESULTS

Multivariable-adjusted odds ratios (ORs) for lower SMMSE score (SMMSE score < 28) were significantly increased in the lowest tertile of serum miR-20a (OR, 2.08; 95% confidence interval (CI), 1.09-4.04) and miR-103a (OR, 1.91; 95%CI, 1.00-3.69) compared to the highest tertile. Moreover, serum levels of miR-20a, -27a, and -103a were linearly and positively associated with SMMSE scores after adjustment for confounding factors.

CONCLUSION

Low serum levels of miR-20a, -27a, and -103a are independently associated with cognitive impairment.

Amyloid Precursor Protein Overexpression in Down Syndrome Trophoblast Reduces Cell Invasiveness and Interferes with Syncytialization

The placentas of Down syndrome (DS) pregnancies exhibit morphologic and functional abnormalities. Although the increase in dosage of certain genes on chromosome 21 has been associated with the DS phenotype, the effects on placenta have seldom been studied. Herein, we examine the expression of four dosage-sensitive genes (APP, ETS2, SOD1, and HMGN1) in normal and DS placentas. We demonstrated significant overexpression of amyloid precursor protein (APP) in DS placentas at RNA and protein levels by real-time quantitative PCR, Western blot analysis, and immunohistochemistry. Inducible APP overexpression trophoblast cell line models were established using a Tet-On system. APP induction in HTR-8/SVneo dose-dependently decelerated cell growth, enhanced apoptosis, and reduced cell migration and invasion when compared with the uninduced controls. Concomitantly, decreased β-human chorionic gonadotropin in the culture medium was also detected on induction. Moreover, although forskolin treatment induced α/β-human chorionic gonadotropin and syncytin expression in BeWo cells, such induction of syncytialization was inhibited by APP overexpression. E-cadherin immunofluorescence also demonstrated a decrease in syncytia formation in forskolin-treated BeWo-overexpressing APP. By liquid chromatography-tandem mass spectrometry, proteins related to cell-cell adhesion, protein translation, processing, and folding were found to be up-regulated in APP-induced HTR-8/SVneo clones. Our data demonstrated, for the first time, the effects of increased APP expression in DS placenta.

Exosomes as secondary inductive signals involved in kidney organogenesis

The subfraction of extracellular vesicles, called exosomes, transfers biological molecular information not only between cells but also between tissues and organs as nanolevel signals. Owing to their unique properties such that they contain several RNA species and proteins implicated in kidney development, exosomes are putative candidates to serve as developmental programming units in embryonic induction and tissue interactions. We used the mammalian metanephric kidney and its nephron-forming mesenchyme containing the nephron progenitor/stem cells as a model to investigate if secreted exosomes could serve as a novel type of inductive signal in a process defined as embryonic induction that controls organogenesis. As judged by several characteristic criteria, exosomes were enriched and purified from a cell line derived from embryonic kidney ureteric bud (UB) and from primary embryonic kidney UB cells, respectively. The cargo of the UB-derived exosomes was analysed by qPCR and proteomics. Several miRNA species that play a role in Wnt pathways and enrichment of proteins involved in pathways regulating the organization of the extracellular matrix as well as tissue homeostasis were identified. When labelled with fluorescent dyes, the uptake of the exosomes by metanephric mesenchyme (MM) cells and the transfer of their cargo to the cells can be observed. Closer inspection revealed that besides entering the cytoplasm, the exosomes were competent to also reach the nucleus. Furthermore, fluorescently labelled exosomal RNA enters into the cytoplasm of the MM cells. Exposure of the embryonic kidney-derived exosomes to the whole MM in an ex vivo organ culture setting did not lead to an induction of nephrogenesis but had an impact on the overall organization of the tissue. We conclude that the exosomes provide a novel signalling system with an apparent role in secondary embryonic induction regulating organogenesis.

MicroRNAs in gynecological cancers: Small molecules with big implications

Gynecological cancers (GCs) are often diagnosed at advanced stages, limiting the efficacy of available therapeutic options. Thus, there remains an urgent and unmet need for innovative research for the efficient clinical management of GC patients. Research over past several years has revealed the enormous promise of miRNAs. These small non-coding RNAs can aid in the diagnosis, prognosis and therapy of all major GCs, viz., ovarian cancers, cervical cancers and endometrial cancers. Mechanistic details of the miRNAs-mediated regulation of multiple biological functions are under constant investigation, and a number of miRNAs are now believed to influence growth, proliferation, invasion, metastasis, chemoresistance and the relapse of different GCs. Modulation of tumor microenvironment by miRNAs can possibly explain some of their reported biological effects. miRNA signatures have been proposed as biomarkers for the early detection of GCs, even the various subtypes of individual GCs. miRNA signatures are also being pursued as predictors of response to therapies. This review catalogs the knowledge gained from collective studies, so as to assess the progress made so far. It is time to ponder over the knowledge gained, so that more meaningful pre-clinical and translational studies can be designed to better realize the potential that miRNAs have to offer.

MicroRNA‑20a promotes inflammation via the nuclear factor‑κB signaling pathway in pediatric pneumonia

Pneumonia is a common respiratory disease worldwide, which is preventable and treatable; however, it is recognized as a leading cause of mortality in children. The present study aimed to investigate the role and mechanism of microRNA (miR)‑20a in inflammation in pediatric pneumonia. Clinical serum samples were collected from children with pneumonia and healthy children. Initially, the serum expression levels of miR‑20a were detected by reverse transcription‑quantitative polymerase chain reaction. Subsequently, A549 cells were randomly divided into four groups: Control group; lipopolysaccharide (LPS; 1 µg/ml) group; LPS + miR‑20a group; and LPS + miR‑20a + pyrrolidine dithiocarbamate (PDTC; 100 mmol/l) group. The concentrations of interleukin‑6 (IL‑6), tumor necrosis factor (TNF)‑α and C‑reactive protein (CRP) in clinical serum samples and A549 cells were determined by ELISA. In addition, the protein expression levels of inhibitor of nuclear factor (NF)‑κB α (IκBα) and phosphorylated (p)‑NF‑κB were measured by western blotting. The results demonstrated that miR‑20a was upregulated in children with pneumonia and in lung cells with LPS‑induced inflammatory injury (P<0.01). In addition, compared with the LPS group, cells in the LPS + miR‑20a group exhibited increased expression levels of IL‑6, TNF‑α and CRP (P<0.05). Overexpression of miR‑20a also resulted in upregulation of the expression levels of IκBα and p‑NF‑κB compared with in the LPS group (P<0.05). Furthermore, treatment with the NF‑κB inhibitor PDTC inhibited the expression of inflammatory factors compared with in the LPS + miR‑20a group (P<0.05). In conclusion, the present study indicated that miR‑20a is upregulated in pediatric pneumonia, and overexpression of miR‑20a may promote inflammation through activation of the NF‑κB signaling pathway.

MicroRNA-20a contributes to cisplatin-resistance and migration of OVCAR3 ovarian cancer cell line

MicroRNAs (miRs) have been reported to be associated with the development of numerous types of cancer. However, the function of miRs in human ovarian carcinoma chemoresistance remains largely undefined. In the present study, cell chemotherapy combined with a Cell Counting Kit-8 assay demonstrated that miR-20a performed important roles in ovarian cancer cells chemoresistance. Flow cytometry, cellular proliferation assays and Transwell assays results revealed that the proliferation and migration rates of OVCAR3/DDP cells were increased in comparison with parental cells. Western blot analysis results suggested that epithelial-mesenchymal transition (EMT) activated by miR-20a contributed to OVCAR3/DDP cell migration. The present study highlighted the importance of miR-20a in regulating the chemoresistant properties of OVCAR3 cells and promoting cisplatin-resistant cell migration by activating EMT. The results of present study may therefore provide novel insights into reversing the chemoresistance of ovarian cancer and improving its treatment.

Effect of SMYD3 on the microRNA expression profile of MCF-7 breast cancer cells

SET and MYND domain containing 3 (SMYD3) is a histone methyltransferase (HMT) and transcription factor, which serves important roles in carcinogenesis. Numerous downstream target genes of SMYD3 have been identified in previous studies. However, the downstream microRNA (miRNA) s regulated by SMYD3 are yet to be elucidated. In the present study, the results of miRNA microarray demonstrated that 30 miRNA expression profiles were upregulated, whilst 24 miRNAs were downregulated by >2.0-fold in the SMYD3-overexpressed MCF-7 breast cancer cells. The HMT activity was demonstrated to be essential for SMYD3-mediated transactivation of miR-200c-3p and the overexpression of miR-200c-3p inhibited the transactivation effects of SMYD3 on myocardin-related transcription factor-A-dependent migration-associated genes. To our best knowledge, the current study is the first to report on the transcriptional regulation of SMYD3 on miRNAs, and miR-200c may be a downstream negative regulator of the SMYD3-mediated pathway in the migration of breast cancer cells. These results may provide a novel theoretical basis to understand the mechanisms underlying the initiation, progression, diagnosis, prevention and therapy of breast cancer.

Bioinformatics prediction and experimental validation of microRNA-20a targeting Cyclin D1 in hepatocellular carcinoma

Hepatocellular carcinoma is the major form of primary liver cancer, which is the second and sixth leading cause of cancer-related death in men and women, respectively. Extensive research indicates that Wnt/β-catenin signaling pathway, which plays a pivotal role in growth, development, and differentiation of hepatocellular carcinoma, is one of the major signaling pathways that is dysregulated in hepatocellular carcinoma. Cyclin D1 is a proto-oncogene and is one of the major regulators of Wnt signaling pathway, and its overexpression has been detected in various types of cancers including hepatocellular carcinoma. Using several validated bioinformatic databases, we predicted that the microRNAs are capable of targeting 3′-untranslated region of Cyclin D1 messenger RNA. According to the results, miR-20a was selected as the highest ranking microRNA targeting Cyclin D1 messenger RNA. Luciferase assay was recruited to confirm bioinformatic prediction results. Cyclin D1 expression was first assessed by quantitative real-time polymerase chain reaction in HepG2 cell line. Afterward, HepG2 cells were transduced by lentiviruses containing miR-20a. Then, the expression of miR-20a and Cyclin D1 was evaluated. The results of luciferase assay demonstrated targeting of 3′-untranslated region of Cyclin D1 messenger RNA by miR-20a. Furthermore, 238-fold decline in Cyclin D1 expression was observed after lentiviral induction of miR-20a in HepG2 cells. The results highlighted a considerable effect of miRNA-20a induction on the down-regulation of Cyclin D1 gene. Our results suggest that miR-20a can be used as a novel candidate for therapeutic purposes and a biomarker for hepatocellular carcinoma diagnosis.

Changes of Ovarian microRNA Profile in Long-Living Ames Dwarf Mice during Aging

The Ames dwarf (df/df) mice have extended longevity and can preserve the ovarian reserve longer than Normal (N) mice. Based on this, the aim of our study was to evaluate the ovarian microRNA (miRNA) profile in young and aged df/df and N mice. Ovarian tissue was collected at 5–6 months and at 21–22 months of age for miRNA sequencing. We detected a total of 404 miRNAs in the ovarian samples, from which the abundance of 22 and 33 miRNAs changed with age in N and df/df mice, respectively. Of these, only three miRNAs were commonly regulated with age between N and df/df mice, indicating a very divergent miRNA profile between genotypes. We also detected that 46 miRNAs were regulated between N and df/df mice, of which 23 were regulated exclusively in young mice, 12 exclusively in old mice and 12 commonly regulated at young and old ages. Many genes likely to be targeted by these miRNAs are involved in the FoxO, mTOR, PI3k/Akt and insulin signaling pathways. These results suggest that the aging process has a differential impact on the ovarian miRNA profile in df/df mice, and suggest that these miRNAs can be central players in the maintenance of a younger ovarian phenotype.

MicroRNA-20a in human faeces as a non-invasive biomarker for colorectal cancer

Objective

Detection of microRNA (miRNA) aberrations in human faeces is a new approach for colorectal cancer (CRC) screening. The aim of this study was to characterise miR-20a in faeces as a non-invasive biomarker for diagnosis of CRC.

Results

miR-20a expression was significantly higher in the 40 CRC tumours compared to their respective adjacent normal tissues (P = 0.0065). Levels of miR-20a were also significantly higher in faecal samples from CRC patients (P < 0.0001). The area under receiver operating characteristic (AUROC) curve for miR-20a was 0.73, with a sensitivity of 55% and specificity of 82% for CRC patients compared with controls. No significant difference in the level of miR-20a was found between patients with proximal, distal, and rectal cancer. The use of antibiotics did not influence faecal miR-20a levels.

Patients and Methods

miR-20a was selected from an expression microarray containing 667 miRNAs. Further verification of miR-20a was performed in 40 pairs of primary CRC tissues, as well as 595 faecal samples (198 CRCs, 199 adenomas, and 198 healthy controls) using TaqMan probe based quantitative Real-Time PCR (qRT-PCR).

Conclusions

Faecal-based miR-20a can be utilised as a potential non-invasive biomarker for CRC screening.

Prioritizing cancer-related microRNAs by integrating microRNA and mRNA datasets

MicroRNAs (miRNAs) are small non-coding RNAs regulating the expression of target genes, and they are involved in cancer initiation and progression. Even though many cancer-related miRNAs were identified, their functional impact may vary, depending on their effects on the regulation of other miRNAs and genes. In this study, we propose a novel method for the prioritization of candidate cancer-related miRNAs that may affect the expression of other miRNAs and genes across the entire biological network. For this, we propose three important features: the average expression of a miRNA in multiple cancer samples, the average of the absolute correlation values between the expression of a miRNA and expression of all genes, and the number of predicted miRNA target genes. These three features were integrated using order statistics. By applying the proposed approach to four cancer types, glioblastoma, ovarian cancer, prostate cancer, and breast cancer, we prioritized candidate cancer-related miRNAs and determined their functional roles in cancer-related pathways. The proposed approach can be used to identify miRNAs that play crucial roles in driving cancer development, and the elucidation of novel potential therapeutic targets for cancer treatment.

shRNA‑mediated silencing of TARBP2 inhibits NCI‑H1299 non‑small cell lung cancer cell invasion and migration via the JNK/STAT3/AKT pathway

Metastasis is a major cause of lung cancer-associated mortality. The current study aimed to investigate the effects and mechanisms of TAR (human immunodeficiency virus 1) RNA binding protein 2 (TARBP2) in the invasion and migration of non‑small cell lung cancer in vitro. The highly metastatic cell clone H1299/M02 was obtained by TARBP2 overexpression. Expression of TARBP2 in H1299/M02 was also downregulated to different levels via small hairpin RNAs (shRNAs). Subsequent to TARBP2 silencing, the proliferation of H1299/M02 cells was predominantly unaffected, while invasion and migration were significantly inhibited. A positive correlation was observed between invasion and migration and the level of TARBP2 silencing in vitro. Western blotting and reverse transcription‑quantitative polymerase chain reaction indicated that the protein expression levels of amyloid β (A4) precursor protein (APP) and zinc finger protein 395 (ZNF395) were upregulated, while expression levels of pro‑metastatic proteins including interleukin (IL)‑1β, IL‑8, cyclooxygenase (COX)‑2, matrix metalloproteinase 2 (MMP2) and MMP9 were downregulated. Phosphorylation of c‑Jun N‑terminal kinase (JNK), signal transducer and activator of transcription 3 (STAT3) and protein kinase B (AKT) were also inhibited. Overexpression of TARBP2 was suggested to be involved in the metastasis of H1299/M02 cells. Silencing of TARBP2 was able to upregulate levels of APP and ZNF395, in addition to inhibiting metastasis‑promoting cytokines, the JNK/STAT3/AKT pathway and COX‑2 to attenuate the invasion and migration of cancer cells.

miR-20a induces cisplatin resistance of a human gastric cancer cell line via targeting CYLD

The dysregulation of microRNAs (miRNAs) has been demonstrated to contribute to drug resistance of cancer cells, and sustained nuclear factor (NF)κB activation is also pivotal in tumor resistance to chemotherapy. In the present study, an essential role for miRNA (miR)-20a was identified in the regulation of gastric cancer (GC) chemoresistance. The expression level of miR‑20a was assayed by reverse transcription‑quantitative polymerase chain reaction. Additionally, 3-(4,5-dimethylthiazol-2‑yl)-2,5-diphenyltetrazolium bromide was used to detect the drug‑resistance phenotype changes of cancer cells associated with upregulation or downregulation of miR‑20a. Protein expression levelss were measured by western blotting and immunohistochemistry. Flow cytometry was used to detect cisplatin‑induced apoptosis. It was found that miR‑20a was markedly upregulated in GC plasma and tissue samples. Additionally, miR‑20a was upregulated in GC plasma and tissues from patients with cisplatin (DDP) resistance, and in the DPP‑resistant gastric cancer cell line (SGC7901/DDP). The expression of miR‑20a was inversely correlated with the expression of cylindromatosis (CYLD). Subsequently, the assessment of luciferase activity verified that CYLD was a direct target gene of miR‑20a. Treatment with miR‑20a inhibitor increased the protein expression of CYLD, downregulated the expression levels of p65, livin and survivin, and led to a higher proportion of apoptotic cells in the SGC7901/DDP cells. By contrast, ectopic expression of miR‑20a significantly repressed the expression of CYLD, upregulated the expression levels of p65, livin and survivin, and resulted in a decrease in the apoptosis induced by DDP in the SGC7901 cells. Taken together, the results of the present study suggested that miR‑20a directly repressed the expression of CYLD, leading to activation of the NFκB pathway and the downstream targets, livin and survivin, which potentially induced GC chemoresistance. Altering miR‑20a expression may be a potential therapeutic strategy for the treatment of chemoresistance in GC in the future.

HPV 16 E7 inhibits OSCC cell proliferation, invasion, and metastasis by upregulating the expression of miR-20a

The aim of this research was to study how HPV-16 E7 affects the proliferation, invasion, and metastasis of oral squamous cell carcinoma (OSCC) cells by upregulating the expression of miR-20a. A total of 60 OSCC patients were included in this study. SiRNA-198 was used to inhibit HPV-16 E7, and the constructed plasmid of HPV-16 E7 was transfected into Cal27 cells. Then, HPV-16 E7 protein was detected by Western blot and RT-PCR was performed to measure miR-20a expression in OSCC cells. Either HPV-16 E7 or the combination of HPV-16 E7 and miR-20a inhibitors was transfected into Cal27 cells separately. And then, the effect of miR-20a on OSCC cells proliferation was evaluated by CCK-8. Moreover, transwell assay and wound healing assay were used to assess the impact of miR-20a on OSCC cell invasion migration. MiR-20a was significantly higher in OSCC tissues compared with para-carcinoma tissues. RT-PCR results indicated that miR-20a was downregulated after silencing HPV-16 E7. By contrast, miR-20a was upregulated after the overexpression of HPV-16 E7. Upregulation of miR-20a by transfected plasmid HPV-16 E7 can significantly inhibit Cal27 cell proliferation, invasion, and migration. The expression of MiR-20a upregulated by HPV-16 E7 inhibits the proliferation, invasion, and migration of OSCC cells.

MicroRNA involvement in a metastatic non-functioning pituitary carcinoma

PURPOSE

Pituitary carcinomas are extremely rare neoplasms, and molecular events leading to malignant pituitary transformation are largely unknown. Enhanced understanding of molecular mechanisms driving malignant pituitary progression would be beneficial for pituitary carcinoma diagnosis and treatment.

METHODS

Differential microRNA expression in paired primary and metastatic pituitary carcinoma specimens were detected using high-throughput human microRNA microarrays and TaqMan microRNA arrays. Three of significantly deregulated miRNAs were further confirmed using quantitative real-time PCR in the metastatic carcinoma, six atypical pituitary adenomas and eight typical pituitary adenomas. Target genes of microRNAs were bioinformatically predicated and verified in vitro by Western blotting and real-time PCR and in vivo by immunohistochemistry respectively.

RESULTS

We present a case of a 50-year-old woman harboring non-functioning pituitary carcinoma with multiple intracranial metastases, and identified up-regulation of miR-20a, miR-106b and miR-17-5p in the metastatic carcinoma as compared to the primary neoplasm. Furthermore, miR-20a and miR-17-5p were increased in the metastatic carcinoma and six atypical pituitary adenomas as compared to eight typical pituitary adenomas as measured by quantitative real-time PCR. Both PTEN and TIMP2 were bioinformatically predicated and confirmed in vitro as target genes of these three microRNAs. As semi-quantified by immunohistochemistry, PTEN was absent and TIMP2 was decreased in the metastatic pituitary carcinoma as compared to pituitary adenomas.

CONCLUSIONS

Our results suggest microRNA involvement in malignant pituitary progression, whereby increased miR-20a, miR-106b and miR-17-5p promote metastasis by attenuating PTEN and TIMP2 in pituitary carcinoma.

miR-20a enhances cisplatin resistance of human gastric cancer cell line by targeting NFKBIB

Drug resistance of cancer cells can be regulated by the dysregulated miRNAs, and sustained NFκB activation also plays an important role in tumor resistance to chemotherapy. Here, we sought to investigate whether there was a correlation between miR-20a and the NFκB pathway to clarify the effects that miR-20a exerted on gastric cancer (GC) chemoresistance. We found that miR-20a was significantly upregulated in GC plasma and tissue samples. In addition, it was upregulated in GC plasma and tissues from patients with cisplatin-resistant gastric cancer cell line SGC7901/cisplatin (DDP). And the upregulation of miR-20a was concurrent with the downregulation of NFKBIB (also known as IκBβ) as well as upregulation of p65, livin, and survivin. The luciferase activity suggested that NFKBIB was the direct target gene of miR-20a. Transfection of miR-20a inhibitor could increase NFKBIB level; downregulate the expression of p65, livin, and survivin; and lead to a higher proportion of apoptotic cells in SGC7901/DDP cells. Conversely, ectopic expression of miR-20a dramatically decreased the expression of NFKBIB; increased the expression of p65, livin, and survivin; and resulted in a decrease in the apoptosis induced by DDP in SGC7901 cells. Taken together, our findings suggested that miR-20a could promote activation of the NFκB pathway and downstream targets livin and survivin by targeting NFKBIB, which potentially contributed to GC chemoresistance.

The epigenetics of aging and neurodegeneration

Epigenetics is a quickly growing field encompassing mechanisms regulating gene expression that do not involve changes in the genotype. Epigenetics is of increasing relevance to neuroscience, with epigenetic mechanisms being implicated in brain development and neuronal differentiation, as well as in more dynamic processes related to cognition. Epigenetic regulation covers multiple levels of gene expression; from direct modifications of the DNA and histone tails, regulating the level of transcription, to interactions with messenger RNAs, regulating the level of translation. Importantly, epigenetic dysregulation currently garners much attention as a pivotal player in aging and age-related neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, where it may mediate interactions between genetic and environmental risk factors, or directly interact with disease-specific pathological factors. We review current knowledge about the major epigenetic mechanisms, including DNA methylation and DNA demethylation, chromatin remodeling and non-coding RNAs, as well as the involvement of these mechanisms in normal aging and in the pathophysiology of the most common neurodegenerative diseases. Additionally, we examine the current state of epigenetics-based therapeutic strategies for these diseases, which either aim to restore the epigenetic homeostasis or skew it to a favorable direction to counter disease pathology. Finally, methodological challenges of epigenetic investigations and future perspectives are discussed.

Differential regulation of aggressive features in melanoma cells by members of the miR-17-92 complex

The various roles of microRNAs (miRNAs) in controlling the phenotype of cancer cells are the focus of contemporary research efforts. We have recently shown that miR-17 directly targets the ADAR1 gene and thereby enhances melanoma cell aggressiveness. miR-17 and miR-20a belong to the miR-17/92 complex, and their mature forms are identical except for two non-seed nucleotides. Nevertheless, here we show that these two miRNAs carry markedly different effects on melanoma cells. A strong positive correlation was observed between the expression of miR-17 and miR-20a among various melanoma cultures. Luciferase assays showed that miR-17 but not miR-20a directly targets the 3’ untranslated region of the ADAR1 gene. Ectopic expression of these miRNAs in melanoma cells differentially alters the expression of five exemplar TargetScan-predicted target genes: ADAR1, ITGB8, TGFBR2, MMP2 and VEGF-A. Whole-genome expression microarrays confirm a markedly differential effect on the transcriptome. Functionally, over-expression of miR-20a but not of miR-17 in melanoma cells inhibits net proliferation in vitro. The differential functional effect was observed following ectopic expression of the mature miRNA or of the pre-miRNA sequences. This suggests that the two non-seed nucleotides dictate target sequence recognition and overall functional relevance. These miRNAs are clearly not redundant in melanoma cell biology.

Silencing ADAM10 inhibits the in vitro and in vivo growth of hepatocellular carcinoma cancer cells

A disintegrin and metalloprotease 10 (ADAM10) is a transmembrane protein associated with metastasis in a number of types of cancer. Little is known, however, regarding the role of ADAM10 in hepatocellular carcinoma (HCC). The aim of the present study was to evaluate whether downregulation of ADAM10 effects HCC cell proliferation, cell cycle, cell migration and cell invasion. A recombinant small hairpin RNA expression vector carrying ADAM10 was constructed and then transfected into the HepG2 human HCC cell line. In vitro cell proliferation, cell cycle, cell migration and cell invasion, and in vivo tumor growth were determined following the downregulation of ADAM10 by RNA interference. The results revealed that downregulation of ADAM10 expression in HepG2 tumor cells using the RNA silencing approach significantly suppressed cell proliferation, cell migration and cell invasion in vitro, and tumor growth in vivo. Furthermore, ADAM10 silencing was able to significantly reduce constitutive phosphorylation of phosphoinositide 3-kinase (PI3K) and Akt, which implies that ADAM10 is, at least partially, involved in the activation of the PI3K/Akt signaling pathway. These results suggest that ADAM10 is important in regulating the proliferation and metastasis of HCC. Thus, ADAM10 is a promising therapeutic target for the prevention of tumor metastases in HCC.

Clinically relevant microRNAs in ovarian cancer

microRNAs (miRNAs/miRs) belong to a class of small noncoding RNAs that can negatively regulate messenger RNA (mRNA) expression of target genes. miRNAs are involved in multiple aspects of ovarian cancer cell dysfunction and the phenotype of ovarian cancer cells can be modified by targeting miRNA expression. miRNA profiling has detected a number of candidate miRNAs with the potential to regulate many important biologic functions in ovarian cancer, but their role still needs to be clarified, given the remarkable heterogeneity among ovarian cancers and the context-dependent role of miRNAs. This review summarizes the data collected from The Cancer Genome Atlas (TCGA) and several other genome-wide projects to identify dysregulated miRNAs in ovarian cancers. Copy number variations (CNVs), epigenetic alterations, and oncogenic mutations are also discussed that affect miRNA levels in ovarian disease. Emphasis is given to the role of particular miRNAs in altering expression of genes in human ovarian cancers with the potential to provide diagnostic, prognostic, and therapeutic targets. Particular attention has been given to TP53, BRCA1/2, CA125 (MUC16), HE4 (WFDC2), and imprinted genes such as ARHI (DIRAS3). A better understanding of the abnormalities in miRNA expression and downstream transcriptional and biologic consequences will provide leads for more effective biomarkers and translational approaches in the management of ovarian cancer.

Metastasis-suppressor transcript destabilization through TARBP2 binding of mRNA hairpins

Aberrant regulation of RNA stability has an important role in many disease states. Deregulated post-transcriptional modulation, such as that governed by microRNAs targeting linear sequence elements in messenger RNAs, has been implicated in the progression of many cancer types. A defining feature of RNA is its ability to fold into structures. However, the roles of structural mRNA elements in cancer progression remain unexplored. Here we performed an unbiased search for post-transcriptional modulators of mRNA stability in breast cancer by conducting whole-genome transcript stability measurements in poorly and highly metastatic isogenic human breast cancer lines. Using a computational framework that searches RNA sequence and structure space, we discovered a family of GC-rich structural cis-regulatory RNA elements, termed sRSEs for structural RNA stability elements, which are significantly overrepresented in transcripts displaying reduced stability in highly metastatic cells. By integrating computational and biochemical approaches, we identified TARBP2, a double-stranded RNA-binding protein implicated in microRNA processing, as the trans factor that binds the sRSE family and similar structural elements--collectively termed TARBP2-binding structural elements (TBSEs)--in transcripts. TARBP2 is overexpressed in metastatic cells and metastatic human breast tumours and destabilizes transcripts containing TBSEs. Endogenous TARBP2 promotes metastatic cell invasion and colonization by destabilizing amyloid precursor protein (APP) and ZNF395 transcripts, two genes previously associated with Alzheimer's and Huntington's disease, respectively. We reveal these genes to be novel metastasis suppressor genes in breast cancer. The cleavage product of APP, extracellular amyloid-α peptide, directly suppresses invasion while ZNF395 transcriptionally represses a pro-metastatic gene expression program. The expression levels of TARBP2, APP and ZNF395 in human breast carcinomas support their experimentally uncovered roles in metastasis. Our findings establish a non-canonical and direct role for TARBP2 in mammalian gene expression regulation and reveal that regulated RNA destabilization through protein-mediated binding of mRNA structural elements can govern cancer progression.

The miR-17/92 cluster: a comprehensive update on its genomics, genetics, functions and increasingly important and numerous roles in health and disease

The miR-17/92 cluster is among the best-studied microRNA clusters. Interest in the cluster and its members has been increasing steadily and the number of publications has grown exponentially since its discovery with more than 1000 articles published in 2012 alone. Originally found to be involved in tumorigenesis, research work in recent years has uncovered unexpected roles for its members in a wide variety of settings that include normal development, immune diseases, cardiovascular diseases, neurodegenerative diseases and aging. In light of its ever-increasing importance and ever-widening regulatory roles, we review here the latest body of knowledge on the cluster's involvement in health and disease as well as provide a novel perspective on the full spectrum of protein-coding and non-coding transcripts that are likely regulated by its members.

MicroRNAs: a connection between cholesterol metabolism and neurodegeneration

Dysregulation of cholesterol metabolism in the brain has been associated with many neurodegenerative disorders such as Alzheimer's disease, Niemann-Pick type C disease, Smith-Lemli-Opitz syndrome, Hungtington's disease and Parkinson's disease. Specifically, genes involved in cholesterol biosynthesis (24-dehydrocholesterol reductase, DHCR24) and cholesterol efflux (ATP-binding cassete transporter, ABCA1, and apolipoprotein E, APOE) have been associated with developing Alzheimer's disease. Indeed, APOE was the first gene variation found to increase the risk of Alzheimer's disease and remains the risk gene with the greatest known impact. Mutations in another cholesterol biosynthetic gene, 7-dehydrocholesterol reductase (DHCR7), cause Smith-Lemli-Opitz syndrome and impairment in cellular cholesterol trafficking caused by mutations in the NPC1 protein results in Niemann-Pick type C disease. Taken together, these findings provide strong evidence that cholesterol metabolism needs to be controlled at very tight levels in the brain. Recent studies have implicated microRNAs (miRNAs) as novel regulators of cholesterol metabolism in several tissues. These small non-coding RNAs regulate gene expression at the post-transcriptional level by either suppressing translation or inducing mRNA degradation. This review article focuses on how cholesterol homeostasis is regulated by miRNAs and their potential implication in several neurodegenerative disorders, such as Alzheimer's disease. Finally, we also discuss how antagonizing miRNA expression could be a potential therapy for treating cholesterol related diseases.

MiR-20a is upregulated in anaplastic thyroid cancer and targets LIMK1

Background

There have been conflicting reports regarding the function of miR-20a in a variety of cancer types and we previously found it to be dysregulated in sporadic versus familial papillary thyroid cancer. In this study, we studied the expression of miR-20a in normal, benign and malignant thyroid samples, and its effect on thyroid cancer cells in vitro and in vivo.

Methodology/Principal Findings

The expression of miR-20a in normal, benign and malignant thyroid tissue was determined by quantitative RT-PCR. Thyroid cancer cells were transfected with miR-20a and the effect on cellular proliferation, tumor spheroid formation, and invasion was evaluated. Target genes of miR-20 were determined by genome-wide mRNA expression analysis with miR-20a overexpression in thyroid cancer cells and target prediction database. Target genes were validated by quantitative PCR and immunoblotting, and luciferase assays. MiR-20a expression was significantly higher in anaplastic thyroid cancer than in differentiated thyroid cancer, and benign and normal thyroid tissues. MiR-20a significantly inhibited thyroid cancer cell proliferation in vitro (p<0.01) and in vivo (p<0.01), tumor spheroid formation (p<0.05) and invasion (p<0.05) in multiple thyroid cancer cell lines. We found that LIMK1 was a target of miR-20a in thyroid cancer cell lines and direct knockdown of LIMK1 recapitulated the effect of miR-20a in thyroid cancer cells.

Conclusions/Significance

To our knowledge, this is the first study to demonstrate that miR-20a plays a role as a tumor suppressor in thyroid cancer cells and targets LIMK1. Our findings suggest the upregulated expression of miR-20a in anaplastic thyroid cancer counteracts thyroid cancer progression and may have therapeutic potential.

Ovarian tumor-associated microRNA-20a decreases natural killer cell cytotoxicity by downregulating MICA/B expression

MicroRNAs (miRNAs) are a class of small non-coding regulatory RNAs, and changes in miRNAs are involved in tumor origin and progression. Studies have shown that miR-20a is overexpressed in human ovarian cancer tissues and that this miRNA enhances long-term cellular proliferation and invasion capabilities. In this study, a positive correlation between serum miR-20a expression and ovarian cancer stage was observed. We found that miR-20a binds directly to the 3'-untranslated region of MICA/B mRNA, resulting in its degradation and reducing its protein levels on the plasma membrane. Reduction of membrane-bound MICA/B proteins, which are ligands of the natural killer group 2 member D (NKG2D) receptor found on natural killer (NK) cells, γδ(+) T cells and CD8(+) T cells, allows tumor cells to evade immune-mediated killing. Notably, antagonizing miR-20a action enhanced the NKG2D-mediated killing of tumor cells in both in vitro and in vivo models of tumors. Taken together, our data indicate that increased levels of miR-20a in tumor cells may indirectly suppress NK cell cytotoxicity by downregulating MICA/B expression. These data provide a potential link between metastasis capability and immune escape of tumor cells from NK cells.

Identification of microRNAs involved in growth arrest and cell death in hydrogen peroxide-treated human dermal papilla cells

microRNAs (miRNAs) are small non‑coding RNAs that regulate various biological processes by interfering with the translation of target genes. Several studies have suggested that miRNAs are involved in cellular responses to hydrogen peroxide (H2O2). Reactive oxygen species (ROS) are involved in hair malignancies, however, the H2O2‑induced, miRNA‑dependent regulatory mechanisms of human dermal papilla (HDP) cells are not fully understood. Our previous study demonstrated that changes in miRNA expression function to regulate growth arrest and apoptosis in UVB‑irradiated HDPs. In the present study, miRNA expression was profiled in HDPs treated with H2O2. The transcriptome analysis of H2O2‑treated HDPs enabled the identification of 68 differentially expressed miRNAs (62 were upregulated and 6 were downregulated) and 14,316 putative target genes of the miRNAs. Gene ontology (GO) analysis was utilized to verify that the putative target genes of the altered miRNAs were associated with H2O2‑induced cell growth arrest and apoptosis. This bioinformatics analysis indicated that H2O2‑response pathways involved in growth arrest and apoptosis were significantly affected. The identification of miRNAs and their putative targets may offer new therapeutic strategies for H2O2‑induced hair follicle disorders.

miR‑20a is an independent prognostic factor in colorectal cancer and is involved in cell metastasis

Accumulating evidence indicates that dysregulated microRNAs (miRNAs) are involved in cancer development, progression and metastasis. miR‑20a was found to be involved in invasion and epithelial‑mesenchymal transition (EMT) programs, with its aberrant expression having been observed in a variety of malignant tumors. However, the molecular mechanisms underlying the role of miR‑20a in colorectal cancer (CRC) development remain to be fully elucidated. In the present study, the expression of miR‑20a was compared between CRC tissue samples and the normal adjacent mucosa using quantitative polymerase chain reaction. The association of miR‑20a expression with clinicopathological characteristics was assessed using appropriate statistical analysis. The migration and invasion of SW480 cells was examined following transfection of the cells with either miR‑20a precursor or a negative control miRNA precursor. The effect of miR‑20a on the EMT in CRC cells in vitro was also analyzed. The regulatory effect of miR‑20a on SMAD family member 4 (SMAD4) was evaluated using a dual‑luciferase reporter assay. Relative expression levels of miR‑20a were significantly higher in CRC tissue than those in the normal adjacent mucosa, and high expression of miR‑20a correlated with lymph node metastases and distant metastases. Kaplan‑Meier analysis indicated that patients with increased miR‑20a levels exhibited unfavorable overall survival. Furthermore, multivariate analysis showed that miR‑20a was an independent prognostic factor. The transfection of SW480 CRC cells with miR‑20a promoted migration and invasion in vitro, and the upregulation of miR‑20a induced EMT in CRC cells. An inverse correlation between the levels of miR‑20a and SMAD4 was observed in patients with CRC. Overexpression of miR‑20a in CRC cells decreased SMAD4 expression and decreased SMAD4‑driven luciferase reporter activity. The present study revealed that miR‑20a was an independent prognostic factor in CRC. Furthermore, miR‑20a induced EMT and regulated migration and invasion of SW480 cells, at least in part via suppression of SMAD4 expression. The present study suggests that miR‑20a may serve as a novel prognostic marker and therapeutic target for CRC.

TGFβR2 is a major target of miR-93 in nasopharyngeal carcinoma aggressiveness

Background

MiR-17-92 cluster and its paralogues have emerged as crucial regulators of many oncogenes and tumor suppressors. Transforming growth factor-β receptor II (TGFβR2), as an important tumor suppressor, is involved in various cancer types. However, it is in cancer that only two miRNAs of this cluster and its paralogues have been reported so far to regulate TGFβR2. MiR-93 is oncogenic, but its targetome in cancer has not been fully defined. The role of miR-93 in nasopharyngeal carcinoma (NPC) still remains largely unknown.

Methods

We firstly evaluated the clinical signature of TGFβR2 down-regulation in clinical samples, and next used a miRNA expression profiling analysis followed by multi-validations, including Luciferase reporter assay, to identify miRNAs targeting TGFβR2 in NPC. In vitro and in vivo studies were performed to further investigate the effects of miRNA-mediated TGFβR2 down-regulation on NPC aggressiveness. Finally, mechanism studies were conducted to explore the associated pathway and genes influenced by this miRNA-mediated TGFβR2 down-regulation.

Results

TGFβR2 was down-regulated in more than 50% of NPC patients. It is an unfavorable prognosis factor contributing to clinical NPC aggressiveness. A cluster set of 4 TGFβR2-associated miRNAs was identified; they are all from miR-17-92 cluster and its paralogues, of which miR-93 was one of the most significant miRNAs, directly targeting TGFβR2, promoting cell proliferation, invasion and metastasis in vitro and in vivo. Moreover, miR-93 resulted in the attenuation of Smad-dependent TGF-β signaling and the activation of PI3K/Akt pathway by suppressing TGFβR2, further promoting NPC cell uncontrolled growth, invasion, metastasis and EMT-like process. Impressively, the knockdown of TGFβR2 by siRNA displayed a consentaneous phenocopy with the effect of miR-93 in NPC cells, supporting TGFβR2 is a major target of miR-93. Our findings were also substantiated by investigation of the clinical signatures of miR-93 and TGFβR2 in NPC.

Conclusion

The present study reports an involvement of miR-93-mediated TGFβR2 down-regulation in NPC aggressiveness, thus giving extended insights into molecular mechanisms underlying cancer aggressiveness. Approaches aimed at blocking miR-93 may serve as a promising therapeutic strategy for treating NPC patients.

Enrichment of ovarian cancer stem-like cells is associated with epithelial to mesenchymal transition through an miRNA-activated AKT pathway

OBJECTIVES

Evidence has indicated that ovarian epithelial cancer-type cells under serum-free culture conditions can form spheroid cells and exhibit characteristics expected of cancer stem-like cells (CSCs). However, the mechanism by which differentiated ovarian cancer cells acquire stem-cell properties during CSC enrichment has needed to be elucidated. Recent studies have demonstrated that induction of epithelial to mesenchymal transition (EMT) can generate CSCs and be associated with tumour aggressiveness and metastasis.

MATERIALS AND METHODS

Ovarian epithelial cancer cell lines, SKOV3 and HO8920, were cultured for spheroid cells and adherent cells. CSC enrichment was investigated using MTT assay, flow cytometery and qRT-PCR and expression level of PI3K/AKT pathway components was analysed by western blotting.

RESULTS

Compared to adherent cells, the spheroid cells expressed mesenchymal markers highly and exhibited significantly more motility; we also observed increases in phosphate AKT1 levels in the spheroid cells. Moreover, transfection of miR-20a or miR-200c led to corresponding reduction in endogenous PTEN protein, while AKT1 and phosphate AKT1 levels were upregulated in miRNAs-transfected cells. Finally, PI3K/AKT pathway inhibitor LY294002 reduced expressions of mesenchymal markers and stem-cell gene activity in spheroid cells, enhancing sensitivity of spheroid cells to paclitaxel treatment.

CONCLUSIONS

Our findings demonstrate that EMT contributed to enrichment of ovarian CSCs in vitro, making EMT targeting in epithelial ovarian cancer a novel therapeutic option.

MicroRNA-339-5p down-regulates protein expression of β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) in human primary brain cultures and is reduced in brain tissue specimens of Alzheimer disease subjects

Alzheimer disease (AD) results, in part, from the excess accumulation of the amyloid-β (Aβ) peptide as neuritic plaques in the brain. The short Aβ peptide is derived from the large transmembrane Aβ precursor protein (APP). The rate-limiting step in the production of Aβ from APP is mediated by the β-site APP-cleaving enzyme 1 (BACE1). Dysregulation of BACE1 levels leading to excess Aβ deposition is implicated in sporadic AD. Thus, elucidating the full complement of regulatory pathways that control BACE1 expression is key to identifying novel drug targets central to the Aβ-generating process. MicroRNAs (miRNAs) are expected to participate in this molecular network. Here, we identified a known miRNA, miR-339-5p, as a key contributor to this regulatory network. Two distinct miR-339-5p target sites were predicted in the BACE1 3'-UTR by in silico analyses. Co-transfection of miR-339-5p with a BACE1 3'-UTR reporter construct resulted in significant reduction in reporter expression. Mutation of both target sites eliminated this effect. Delivery of the miR-339-5p mimic also significantly inhibited expression of BACE1 protein in human glioblastoma cells and human primary brain cultures. Delivery of target protectors designed against the miR-339-5p BACE1 3'-UTR target sites in primary human brain cultures significantly elevated BACE1 expression. Finally, miR-339-5p levels were found to be significantly reduced in brain specimens isolated from AD patients as compared with age-matched controls. Therefore, miR-339-5p regulates BACE1 expression in human brain cells and is most likely dysregulated in at least a subset of AD patients making this miRNA a novel drug target.

Nodes and biological processes identified on the basis of network analysis in the brain of the senescence accelerated mice as an Alzheimer's disease animal model

Harboring the behavioral and histopathological signatures of Alzheimer's disease (AD), senescence accelerated mouse-prone 8 (SAMP8) mice are currently considered a robust model for studying AD. However, the underlying mechanisms, prioritized pathways and genes in SAMP8 mice linked to AD remain unclear. In this study, we provide a biological interpretation of the molecular underpinnings of SAMP8 mice. Our results were derived from differentially expressed genes in the hippocampus and cerebral cortex of SAMP8 mice compared to age-matched SAMR1 mice at 2, 6, and 12 months of age using cDNA microarray analysis. On the basis of PPI, MetaCore and the co-expression network, we constructed a distinct genetic sub-network in the brains of SAMP8 mice. Next, we determined that the regulation of synaptic transmission and apoptosis were disrupted in the brains of SAMP8 mice. We found abnormal gene expression of RAF1, MAPT, PTGS2, CDKN2A, CAMK2A, NTRK2, AGER, ADRBK1, MCM3AP, and STUB1, which may have initiated the dysfunction of biological processes in the brains of SAMP8 mice. Specifically, we found microRNAs, including miR-20a, miR-17, miR-34a, miR-155, miR-18a, miR-22, miR-26a, miR-101, miR-106b, and miR-125b, that might regulate the expression of nodes in the sub-network. Taken together, these results provide new insights into the biological and genetic mechanisms of SAMP8 mice and add an important dimension to our understanding of the neuro-pathogenesis in SAMP8 mice from a systems perspective.

Candidate microRNA biomarkers in human gastric cancer: a systematic review and validation study

Gastric cancer (GC) remains a major cause of morbidity and mortality worldwide and there is therefore a clear need to search for more sensitive early diagnostic biomarkers. We performed a systematic review of eight published miRNA profiling studies that compared GC tissues with adjacent noncancerous tissues. A miRNA ranking system was used that took the frequency of comparisons, direction of differential expression and total sample size into consideration. We identified five miRNAs that were most consistently reported to be upregulated (miR-21, miR-106b, miR-17, miR-18a and miR-20a) and two miRNAs that were downregulated (miR-378 and miR-638). Six of these were further validated in 32 paired sets of GC and adjacent noncancerous tissue samples using real-time PCR. MiR-21, miR-106b, miR-17, miR-18a and miR-20a were confirmed to be upregulatedin GC tissues, while the expression of miR-378 was decreased. Moreover, we found a significant association between expression levels of miR-21, miR-106b, miR-17, miR-18a and miR-20a and clinicopathological features of GC. These miRNAs may be used for diagnostic and/or prognostic biomarkers for GC and therefore warrant further investigation.

MiR-20a triggers metastasis of gallbladder carcinoma

BACKGROUND & AIMS

The dysfunction of miRNAs has been demonstrated to participate in the development of various tumors. However, whether miRNAs are involved in metastasis and progression of gallbladder carcinoma (GBC) remains unknown.

METHODS

A new designed gain-of-function miRNA screening technology was applied to filter out pro-metastatic miRNAs in GBC. Their expression in GBC tissues was validated by real-time PCR. The biological functions of miRNAs were intensively studied by transwell, immunoblot, immunohistochemical, and in situ hybridization assays. Tumorigenicity and liver metastasis were further examined in nude mice.

RESULTS

Of 880 miRNAs, 17 were filtered out as the prominent metastatic inducers of GBCs. Among them, the upregulation of pro-metastatic miR-20a was closely associated with local invasion, distant metastasis, and poor prognosis of 67 followed-up GBC patients, clinically. Patients with higher miR-20a expression exhibited worse overall survival (OS and median OS time was 5 and 20 months, respectively) than the lower expression group. A dramatically increased TGF-β1 level was found in GBC patients, which was responsible for the elevation of miR-20a. The ectopic expression of miR-20a could induce epithelial-mesenchymal transition and enhance metastasis of GBC cells in vitro and in vivo, by directly targeting the 3' UTR of Smad7, and subsequently promoting nuclear translocation of β-catenin. Conversely, the blockage of miR-20a by specific antagomir effectively restored the expression of Smad7 and attenuated TGF-β-induced cell metastasis.

CONCLUSIONS

TGF-β1-mediated activation of the miR-20a/Smad7/β-catenin axis plays a pivotal role in the pathogenesis and worse prognosis of GBCs and may serve as a potential therapeutic target in the future.

Epigenetic mechanisms in Alzheimer's disease: implications for pathogenesis and therapy

The vast majority of Alzheimer's disease (AD) are late-onset forms (LOAD) likely due to the interplay of environmental influences and individual genetic susceptibility. Epigenetic mechanisms, including DNA methylation, histone modifications and non-coding RNAs, constitute dynamic intracellular processes for translating environmental stimuli into modifications in gene expression. Over the past decade it has become increasingly clear that epigenetic mechanisms play a pivotal role in aging the pathogenesis of AD. Here, we provide a review of the major mechanisms for epigenetic modification and how they are reportedly altered in aging and AD. Moreover, we also consider how aberrant epigenetic modifications may lead to AD pathogenesis, and we review the therapeutic potential of epigenetic treatments for AD.

MicroRNA-10b promotes the migration of mouse bone marrow-derived mesenchymal stem cells and downregulates the expression of E-cadherin

The ability of mesenchymal stem cells (MSCs) to migrate is an important determinant of the efficiency of MSC transplant therapy. MicroRNA-10b (miR-10b) has been positively involved in the migration of a number of tumor cells lineages. To date, it remains unknown whether miR-10b affects the migration of MSCs. In the current study, the effect of miR-10b on the migration of mouse bone marrow-derived MSCs (bmMSCs) was investigated. Third-passage bmMSCs were transfected with miR-10b mimic and negative control precursor miRNA using Lipofectamine™ 2000. miR-10b and E-cadherin expression and bmMSC migration were determined. The present results showed that primary bmMSCs exhibit a spindled or triangular morphology and that third‑passage bmMSCs present a typical fibroblast-like morphology, exhibiting CD90-positive and CD45-negative expression. Compared with the transfection of negative control miRNA, transfection of miR-10b mimic markedly upregulated miR-10b expression in bmMSCs, increased their migration and downregulated E-cadherin expression. The current observations indicate that the upregulation of miR-10b increases bmMSC migration ability, which may be involved in the downregulation of E-cadherin.