Emerging roles of microRNAs in cancer

MicroRNA-508 is downregulated in clear cell renal cell carcinoma and targets ZEB1 to suppress cell proliferation and invasion

Recent studies have identified several microRNAs (miRNAs/miRs) that are dysregulated in clear cell renal cell carcinoma (ccRCC), and their dysregulation may serve important roles in the occurrence and development of ccRCC. Therefore, understanding the expression pattern and functional roles of miRNAs in ccRCC may facilitate the identification of novel therapeutic targets for the treatment of ccRCC. In the current study, reverse transcription-quantitative polymerase chain reaction was used to determine miR-508 expression levels in ccRCC tissue samples and cell lines. The cell counting kit-8 and in vitro Transwell invasion assays were used to examine the effects of miR-508 overexpression on ccRCC cell proliferation and invasion, respectively. In addition, bioinformatics analysis and dual-luciferase reporter gene assays were used to investigate the underlying mechanism of miR-508 in ccRCC cells. Furthermore, the regulatory role of miR-508 on zinc finger E-box-binding homeobox 1 (ZEB1) mRNA and protein expression in ccRCC cells was investigated using RT-qPCR and western blot analysis, respectively. Additionally, the association between miR-508 and ZEB1 expression in ccRCC tissue samples was examined. Rescue experiments were performed to determine whether the tumor suppressive effects of miR-508 may be mediated by ZEB1 in ccRCC cells. The results of the current study demonstrated that miR-508 expression was significantly downregulated in ccRCC tissue samples and cell lines. In addition, miR-508 overexpression significantly decreased the proliferation and invasion of ccRCC cells. ZEB1 was identified as a direct target gene of miR-508 in ccRCC cells and the relative expression level of ZEB1 mRNA was significantly increased in ccRCC tissue samples. Furthermore, a negative correlation between miR-508 and ZEB1 expression was identified in ccRCC tissues. ZEB1 knockdown exhibited a functional role similar to miR-508 overexpression in ccRCC cells, and restoration of ZEB1 expression significantly reversed the inhibitory effects of miR-508 on the malignant phenotype of ccRCC cells. Taken together, the results of the current study demonstrated that miR-508 may serve a tumor suppressive role in ccRCC via direct targeting of ZEB1. MiR-508 may present a novel and efficient therapeutic target for the treatment of patients with ccRCC.

Single Nucleotide Polymorphisms in MIR143 Contribute to Protection Against Non-Hodgkin Lymphoma (NHL) in Caucasian Populations

Recent studies show an association of microRNA (miRNA) polymorphisms (miRSNPs) in different cancer types, including non-Hodgkin lymphoma (NHL). The identification of miRSNPs that are associated with NHL susceptibility may provide biomarkers for early diagnosis and prognosis for patients who may not respond well to current treatment options, including the immunochemotherapy drug combination that includes rituximab, cyclophosphamide, doxorubicin, vincristine and prednisome (R-CHOP). We developed a panel of miRSNPs for genotyping while using multiplex PCR and chip-based mass spectrometry analysis in an Australian NHL case-control population (300 cases, 140 controls). Statistical association with NHL susceptibility was performed while using Chi-square (χ²) and logistic regression analysis. We identified three SNPs in MIR143 that are to be significantly associated with reduced risk of NHL: rs3733846 (odds ratio (OR) [95% confidence interval (CI)] = 0.54 [0.33–0.86], p = 0.010), rs41291957 (OR [95% CI] = 0.61 [0.39–0.94], p = 0.024), and rs17723799 (OR [95% CI] = 0.43 [0.26–0.71], p = 0.0009). One SNP, rs17723799, remained significant after correction for multiple testing (p = 0.015). Subsequently, we investigated an association between the rs17723799 genotype and phenotype by measuring target gene Hexokinase 2 (HKII) expression in cancer cell lines and controls. Our study is the first to report a correlation between miRSNPs in MIR143 and a reduced risk of NHL in Caucasians, and it is supported by significant SNPs in high linkage disequilibrium (LD) in a large European NHL genome wide association study (GWAS) meta-analysis.

DNA methylation-mediated silencing of miR-204 is a potential prognostic marker for papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy and its incidence has increased over the last few decades. The molecular mechanisms underlying PTC tumorigenesis and progression are still unclear.

PATIENTS AND METHODS

The microRNA (miRNA) expression patterns of PTC were revealed by miRNA microarray analysis and validated with The Cancer Genome Atlas (TCGA) data. Promoter DNA methylation rates of miR-204 were analyzed by Agena Methylation MassAR-RAY analysis and validated with TCGA data. The underlying molecular mechanisms of miR-204 involved in PTC were studied by bioinformatics analyses.

RESULTS

A total of 181 differentially expressed miRNAs (89 downregulated and 92 upregulated miRNAs) between PTC and normal tissues were detected in this study. We identified miR-204 as one of the most significantly downregulated miRNAs in PTC. Downregulation of miR-204 was related to PTC extrathyroidal extension, high T-stage, lymph metastasis, BRAF V600E mutation, and aggressive tall cell variant. The Agena MassARRAY results indicated that 12 CpG sites located at the promoter of miR-204 were hypermethylated in PTC tissues compared to normal tissues. The promoter methylation rates of miR-204 in PTC were negatively correlated with the expression levels of miR-204 and its host gene TRPM3. Downregulated miR-204 expression was related to several important pathways and mechanisms involved in tumorigenesis and progression.

CONCLUSION

Promoter DNA methylation-silenced miR-204 could serve as a potential diagnostic biomarker of PTC. Downregulation of miR-204 may play an important role in PTC via its involvement in many tumor-related pathways. Novel target genes and putative mechanisms of miR-204 in PTC need to be further validated.

miRNA functions in stem cells and their niches: lessons from the Drosophila ovary

From the very beginning of the miRNA era, Drosophila has served as an excellent model for explanation of miRNA biogenesis. Now Drosophila continues to be used in numerous studies aiming to decipher biological roles of individual miRNAs in a living organism. MiRNAs have emerged as an important regulatory class that adjusts gene expression in response to stress; therefore, it is particularly important to elucidate miRNA-based regulatory networks that appear in response to fluctuations in intrinsic and extrinsic environments. This review explores the major advances in understanding condition-dependent roles of miRNAs in adult stem cell biology using the Drosophila ovarian germline stem cell niche community as a model system.

Reduced Levels of miR-28 and miR-200a Act as Predictor Biomarkers of Aggressive Clinicopathological Characteristics in Gastric Cancer Patients

Background:

MicroRNAs (miRNAs) play critical roles in different pathological processes including cancer development and progression. To find novel molecular diagnostic and prognostic markers and promising therapeutic tools for gastric cancer (GC), we aimed to investigate the relationship of the expression levels of miR–28–5p or miR–200a–3p with the clinicopathological criteria and to explore their impacts on the progression of human GC.

Materials and Methods:

Quantitative RT–PCR was performed to analyze miR–28 and miR–200a expression in 60 GC and 60 non–GC tissue samples.

Result:

Our results revealed that the expressions of miR–200a and miR–28 were significantly downregulated in GC in comparison with non– GC tissues. Tumors with low miR–28 expression had larger tumor size, more advanced histological grade, and a higher incidence of lymph node and distal metastasis than the tumors with high miR–28 expressions. Furthermore, receiver operating characteristic (ROC) analyses demonstrate that the expression of miR–28 is a predictive biomarker allows predicting the histological grade, tumor size, and occurrence of nodal and distal metastases. We also found a significant inverse association between miR–200a expression and the rate of lymph node metastasis (p = 0.010, r = –0.334).

Conclusion:

Our findings suggest that the miR–28 and miR–200a have tumor–suppressor functions and may be considered as potential biomarkers for gastric cancer diagnosis and prognosis.

MicroRNA expression in pediatric intracranial ependymomas and their potential value for tumor grading

Intracranial ependymoma represents one of the most common pediatric central nervous system malignancies, and exhibits a wide range of clinical behavior from relatively indolent lesions to highly malignant anaplastic ependymomas. Due to the heterogeneous nature of this disease there is lack of prognostic markers, which would reliably predict the outcome of patients. MicroRNAs (miRNAs) have emerged as important molecules in cancer biology during past decade; however, very little is known about their role in ependymomas. The aim of the present study was to evaluate expression of miRNAs in archived formalin-fixed paraffin-embedded (FFPE) samples of pediatric intracranial ependymomas. The expression of miRNAs were examined in 29 samples of ependymoma and we observed that miR-135a-3p, miR-137, miR-17-5p, miR-181d and let-7d-5p were upregulated. In addition, a significantly higher expression of miR-203a was detected in Grade III tumors suggesting its possible use as a prognostic or diagnostic marker. The present study also demonstrated that storage of (FFPE) ependymoma samples for >20 years did not result in a deterioration of miRNAs. The present findings broaden the presently available knowledge regarding miRNA expression in ependymomas and provide further evidence for the employment of miRNA analysis as a supplementary method for the morphological assessment of ependymoma samples.

Cancer Gene Discovery: Past to Present

Cancer is a complex disease that originates from genetic changes leading to multiple phenotypic manifestations that ultimately result in suffering and death from cancer. Attempts have been made to define the phenotypic and genetic "hallmarks" of cancer, but many of these "hallmarks" remain descriptive, while the underlying mechanisms responsible for these hallmarks remain elusive. For decades, cancer researchers have been methodically identifying the molecular mechanisms that result in tumor initiation, growth, metastases, and resistance to therapy. Great strides forward have been made and we are entering an era of "precision medicine" with the goal of treating each cancer based on its unique etiology. Increasingly, the decision to use targeted therapies and immunotherapies in the clinic is based on the genotype of the cancer being treated. For example, specific tyrosine kinase inhibitors are only prescribed to patients that express the tyrosine kinase protein on their cancer cells. Likewise, a genetically unstable cancer is predictive for successful immunotherapy. Knowledge of the specific genetic changes that result in overproduction of oncogenes and reduced production of tumor suppressors is crucial for advancing therapeutic options for cancer. The first chapter of this book presents a brief history of cancer gene discovery. In the remaining chapters of this book, we present protocols using in silico, in vitro, and in vivo techniques for identifying genetic drivers of cancer, in the hope that these protocols will be used to increase our knowledge of the molecular mechanisms driving cancer.

Circular RNA circRHOT1 is upregulated and promotes cell proliferation and invasion in pancreatic cancer

Aim: We aimed to identify the roles of circRHOT1 in pancreatic cancer. Materials & methods: The circRHOT1 was acquired from our previous study followed by quantitative real-time PCR and fluorescence in situ hybridization validation in pancreatic cancer. We used siRNA and shRNA to explore the function of circRHOT1 in pancreatic cancer cells. Bioinformatic analyses were applied to study the potential mechanism of circRHOT1. Results: The circRHOT1 was upregulated in pancreatic cancer and predominantly located in the cytoplasm. Reducing the circRHOT1 expression may inhibit the pancreatic cancer cell proliferation, invasion and migration. The circRHOT1 may play a role in pancreatic cancer through binding miR-26b, miR-125a, miR-330 and miR-382 to regulate multiple tumor-associated pathways. Conclusion: This study demonstrated that circRHOT1 may serve as an oncogenic circRNA that promotes tumor progression.

microRNA diagnostic panel for Alzheimer's disease and epigenetic trade-off between neurodegeneration and cancer

microRNAs (miRNAs) have been extensively studied as potential biomarkers for Alzheimer's disease (AD). Their profiles have been analyzed in blood, cerebrospinal fluid (CSF) and brain tissue. However, due to the high variability between the reported data, stemming from the lack of methodological standardization and the heterogeneity of AD, the most promising miRNA biomarker candidates have not been selected. Our literature review shows that out of 137 miRNAs found to be altered in AD blood, 36 have been replicated in at least one independent study, and out of 166 miRNAs reported as differential in AD CSF, 13 have been repeatedly found. Only 3 miRNAs have been consistently reported as altered in three analyzed specimens: blood, CSF and the brain (hsa-miR-146a, hsa-miR-125b, hsa-miR-135a). Nonetheless, all 36 repeatedly differential miRNAs in AD blood are promising as components of the diagnostic panel. Given their predicted functions, such miRNA panel may report multiple pathways contributing to AD pathology, enabling the design of personalized therapies. In addition, the analysis revealed that the miRNAs dysregulated in AD overlap highly with miRNAs implicated in cancer. However, the directions of the miRNA changes are usually opposite in cancer and AD, indicative of an epigenetic trade-off between the two diseases.

Inhibition of microRNA‑492 attenuates cell proliferation and invasion in retinoblastoma via directly targeting LATS2

Numerous studies have demonstrated that microRNAs (miRNAs) are upregulated or downregulated in retinoblastoma (RB), and that this phenomenon is associated with the modulation of various malignant behaviours during RB occurrence and development. Therefore, the mechanisms that associate deregulated miRNAs with RB initiation and progression must be understood to identify effective therapeutic techniques for patients with RB. In the present study, miR‑492 expression was upregulated in RB tissues and cell lines. The effects of miR‑492 inhibition on the proliferation and invasion of RB cells were examined using Cell Counting kit‑8 and invasion assays. The results revealed that miR‑492 downregulation significantly decreased the proliferation and invasion of RB cells. Bioinformatics analysis predicted that large tumour‑suppressor kinase 2 (LATS2) was a putative target of miR‑492. Luciferase reporter assay, reverse transcription‑quantitative polymerase chain reaction and western blot analysis demonstrated that LATS2 was a direct target gene of miR‑492 in RB cells. In addition, LATS2 expression was downregulated in RB tissues, and its downregulation was inversely correlated with miR‑492 level. Furthermore, LATS2‑knockdown abrogated the effects of miR‑492 downregulation in RB cells. In conclusion, miR‑492 inhibition may impede the malignant behaviour of RB by directly targeting LATS2. Therefore, targeting this miRNA may be an effective therapeutic method for treating patients with RB.

MiR-125b-1-3p Exerts Antitumor Functions in Lung Carcinoma Cells by Targeting S1PR1

Background

MicroRNAs (miRNAs) have been extensively studied over the decades and have been identified as potential molecular targets for cancer therapy. To date, many miRNAs have been found participating in the tumorigenesis of non-small cell lung cancer (NSCLC). The present study was designed to evaluate the functions of miR-125b-1-3p in NSCLC cells.

Methods

MiR-125b-1-3p expression was detected in tissue samples from 21 NSCLC patients and in NSCLC cell lines using the real-time polymerase chain reaction. A549 cell lines were transfected with a miR-125b-1-3p mimic or miR-125b-1-3p antisense. Cell counting kit-8, wound healing, Matrigel invasion assays, and flow cytometry were used to assess the effects of these transfections on cell growth, migration, invasion, and apoptosis, respectively. Western blotting was used to detect apoptosis-related proteins, expression of S1PR1, and the phosphorylation status of STAT3. Significant differences between groups were estimated using Student's t-test or a one-way analysis of variance.

Results

MiR-125b-1-3p was downregulated in NSCLC samples and cell lines. Overexpression of miR-125b-1-3p inhibited NSCLC cell proliferation (37.8 ± 9.1%, t = 3.191, P = 0.013), migration (42.3 ± 6.7%, t = 6.321, P = 0.003), and invasion (57.6 ± 11.3%, t = 4.112, P = 0.001) and simultaneously induced more NSCLC cell apoptosis (2.76 ± 0.78 folds, t = 3.772, P = 0.001). MiR-125b-1-3p antisense resulted in completely opposite results. S1PR1 was found as the target gene of miR-125b-1-3p. Overexpression of miR-125b-1-3p inhibited S1PR1 protein expression (27.4 ± 6.1% of control, t = 4.083, P = 0.007). In addition, S1PR1 siRNA decreased STAT3 phosphorylation (16.4 ± 0.14% of control, t = 3.023, P = 0.015), as in cells overexpressing miR-125b-1-3p (16.7 ± 0.17% of control, t = 4.162, P = 0.026).

Conclusion

Our results suggest that miR-125b-1-3p exerts antitumor functions in NSCLC cells by targeting S1PR1.

The miRNA Expression Profile of Experimental Autoimmune Encephalomyelitis Reveals Novel Potential Disease Biomarkers

Multiple sclerosis (MS) is a debilitating autoimmune disease affecting over 2.3 million people worldwide, and it is characterized by inflammation and demyelination of nerve cells. The currently available biomarkers for the diagnosis and management of MS have inherent limitations, therefore, additional new biomarkers are needed. We studied the microRNA (miRNA) profile of splenocytes of mice having experimental autoimmune encephalomyelitis (EAE), a model of human MS. A miRNA-microarray analysis revealed increased expression of nine miRNAs (let-7e, miR-23b, miR-31, miR-99b, miR-125a, miR-146b, miR-155, miR-193b, and miR-221) following EAE development. Interestingly, serum levels of miR-99b, miR-125a, and miR-146b were significantly higher in EAE mice compared to normal mice. Bioinformatics analysis revealed the experimentally validated as well as predicted gene targets of specific miRNAs that are important for disease progression in MS. Specifically, we observed inverse correlation in the levels of miR-99b versus LIF, and between miR-125a versus BDNF and LIF. Our results suggest that above-mentioned miRNAs may play a crucial role in the pathogenesis of MS, and that miR-99b, miR-125a, and miR-146b in particular may serve as useful biomarkers for disease activity.

Evaluation of pre-mir-34a rs72631823 single nucleotide polymorphism in triple negative breast cancer: A case-control study

AIM

The purpose of this study is to evaluate the role of pre-miR34a rs72631823 as potential risk factor and/or prognostic marker in patients with triple negative breast cancer.

METHODS

114 samples of DNA from paraffin embedded breast normal tissues of patients with triple negative breast cancer and 124 samples of healthy controls were collected and analyzed for pre-miR34a rs72631823 polymorphism.

RESULTS

Pre-miR34a rs72631823 A allele was associated with increased TNBC risk both in univariate and multivariate analysis. The number of pre-miR34a rs72631823 AA subjects was very small and the association did not reach significance (p = 0.176, Fisher's exact test). The examined polymorphism was not associated with overall survival at the univariate or multivariate Cox regression analysis (adjusted HR = 1.60, 95%CI: 0.64-3.96 for miR34 rs72631823 GA/AA vs. GG).

CONCLUSION

Our case-control study suggests that pre-miR34a rs72631823 A allele is associated with increased triple negative breast cancer risk.

MicroRNA-423-5p inhibits the progression of trophoblast cells via targeting IGF2BP1

INTRODUCTION

Preeclampsia (PE) is one of the leading causes of maternal and fetal mortality globally. The imbalance of trophoblast homeostasis is closely linked with the pathogenesis of PE. MicroRNA-423-5p (miR-423-5p) has been reported to be abnormally expressed in placenta and blood plasma of pregnant women with PE. In the present study, miR-423-5p expression in blood plasma of pregnant women with PE and healthy pregnant women was detected. Also, the roles and molecular mechanisms of miR-423-5p in the development of trophoblast cells were further investigated.

METHODS

Expression of miR-423-5p and insulin like growth factor 2 mRNA binding protein 1 (IGF2BP1) mRNA was detected by RT-qPCR assay. Protein expression of IGF2BP1, Bcl-2 and Bax was determined using western blot assay. Cell migratory and invasive capacities were assessed by transwell migration and invasion assay. Cell apoptotic rate was determined using flow cytometry via the double-staining of Annexin V-FITC/Propidium Iodide. The interaction between miR-423-5p and IGF2BP1 was demonstrated by bioinformatics analysis and luciferase reporter assay.

RESULTS

MiR-423-5p was highly expressed in blood plasma of pregnant women with PE. MiR-423-5p inhibited migration, invasion and proliferation as well as induced apoptosis in HTR-8/SVneo cells. Further investigation revealed that IGF2BP1 was a target of miR-423-5p. Moreover, IGF2BP1 overexpression promoted migration, invasion and proliferation, suppressed apoptosis, and weakened miR-423-5p function in HTR-8/SVneo cells.

DISCUSSION

MiR-423-5p inhibited migration, invasion and proliferation as well as induced apoptosis by targeting IGF2BP1 in HTR-8/SVneo cells, presenting a novel molecular basis implicated in PE pathogenesis.

MicroRNA‑363‑3p inhibits hepatocarcinogenesis by targeting HMGA2 and is associated with liver cancer stage

The importance of microRNAs (miRNAs) in cancer development has been widely recognized in recent decades. In the present study, the function and mechanism of miRNA-363-3p (miR-363-3p), formerly characterized as a tumor suppressor, in the hepatocarcinogenesis of liver cancer cells was investigated. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to detect the expression of miR-363-3p in liver cancer tissues. Cell proliferation, survival and migration capacities were determined by MTT, colony formation and wound-healing assays, respectively. The targeting of high mobility group AT-hook 2 (HMGA2) mRNA by miR-363-3p was confirmed by bioinformatics analysis, and RT-qPCR, luciferase reporter and western blot assays. The correlation between the expression levels of HMGA2 and miR-363-3p was analyzed. The RT-qPCR results revealed that the levels of miR-363-3p were downregulated in liver cancer tissues. Cellular assays validated that miR-363-3p exerted tumor suppressing functions, including the inhibition of cell proliferation, survival and migration abilities in two liver cancer cell lines. Bioinformatics prediction and subsequent experiments demonstrated that HMGA2 was a direct target of miR-363-3p. Restoration of the expression of HMGA2 in miR-363-3p mimic-transfected cells reversed the tumor suppressing effects caused by miR-363-3p. Finally, there was a significant negative correlation between the expression levels of HMGA2 and miR-363-3p in liver cancer tissues. miR-363-3p was identified as an important tumor suppressor in liver cancer via targeting HMGA2, which may have potential benefits in liver cancer therapy.

MicroRNA‑663 inhibits the proliferation and invasion of clear cell renal cell carcinoma cells by directly targeting PAK4

Accumulating evidence has demonstrated that microRNAs (miRNAs) are key gene regulators and are abnormally expressed in clear cell renal cell carcinoma (ccRCC). The dysregulation of miRNAs has been implicated in the initiation and progression of ccRCC. Therefore, identification of ccRCC‑associated miRNAs may facilitate the determination of promising therapeutic targets for anti‑cancer treatment. In the present study, miRNA‑663 (miR‑663) expression was downregulated in ccRCC tissues and cell lines. Functional experiments suggested that restoration of miR‑663 expression inhibited the proliferation and invasion of ccRCC cells. In addition, p21 activated kinase 4 (PAK4) was validated as a direct target of miR‑663 in ccRCC cells. PAK4 was upregulated in ccRCC tissues, and the expression level of PAK4 was inversely correlated with the miR‑663 expression level. PAK4 restoration partially attenuated the suppressive roles of miR‑663 overexpression on the proliferation and invasion of ccRCC cells. The present results provide novel insight into the mechanism underlying the occurrence and development of ccRCC, suggesting that the miR‑663/PAK4 axis may be a novel therapeutic target for treatment of patients with ccRCC.

miR-338-3p Is Regulated by Estrogens through GPER in Breast Cancer Cells and Cancer-Associated Fibroblasts (CAFs)

Estrogens acting through the classic estrogen receptors (ERs) and the G protein estrogen receptor (GPER) regulate the expression of diverse miRNAs, small sequences of non-coding RNA involved in several pathophysiological conditions, including breast cancer. In order to provide novel insights on miRNAs regulation by estrogens in breast tumor, we evaluated the expression of 754 miRNAs by TaqMan Array in ER-negative and GPER-positive SkBr3 breast cancer cells and cancer-associated fibroblasts (CAFs) upon 17β-estradiol (E2) treatment. Various miRNAs were regulated by E2 in a peculiar manner in SkBr3 cancer cells and CAFs, while miR-338-3p displayed a similar regulation in both cell types. By METABRIC database analysis we ascertained that miR-338-3p positively correlates with overall survival in breast cancer patients, according to previous studies showing that miR-338-3p may suppress the growth and invasion of different cancer cells. Well-fitting with these data, a miR-338-3p mimic sequence decreased and a miR-338-3p inhibitor sequence rescued the expression of genes and the proliferative effects induced by E2 through GPER in SkBr3 cancer cells and CAFs. Altogether, our results provide novel evidence on the molecular mechanisms by which E2 may regulate miR-338-3p toward breast cancer progression.

A novel feedback loop between high MALAT-1 and low miR-200c-3p promotes cell migration and invasion in pancreatic ductal adenocarcinoma and is predictive of poor prognosis

Background

It was demonstrated that long non-coding RNAs occupied an important position in tumor pathogenesis and progression. We have previously found that the metastasis-associated lung adenocarcinoma transcript 1 (MALAT-1) promotes cell proliferation and metastases in pancreatic ductal adenocarcinoma (PDAC). The present study was aimed to discuss the underlying mechanisms.

Methods

Bioinformatics method was used to identify the miRNA target of MALAT-1. Expressions of relative genes were assessed by quantitative real-time PCR and western blotting, respectively. Sulforhodamine B assay and Transwell assay were employed to detect cell proliferation, migration and invasion, respectively. Moreover, RNA immunoprecipitation was performed to determine whether RNA-induced silencing complex contained MALAT-1 and its potential binding miRNA. Luciferase assays was used to confirm potential binding site.

Results

Bioinformatics search predicted that miR-200c-3p was a direct target of MALAT-1. Further, we found a reciprocal suppression between MALAT-1 and miR-200c-3p expression. In terms of mechanisms, high MALAT-1 and low miR-200c-3p may form a novel feedback loop. On the one hand, MALAT-1 functioned as a competing endogenous RNA to suppress miR-200c-3p expression, leading to upregulation of ZEB1 expression. On the other hand, miR-200c-3p inhibited the level of MALAT-1 expression was in a way similar to miRNA-mediated downregulation of target genes. Clinical data further indicated that MALAT-1 and ZEB1 expression was negatively correlated with miR-200c-3p transcript level of PDAC tissues. There was a positive correlation between MALAT-1 and ZEB1 level. MALAT-1 (high)/miR-200c-3p (low) correlated with shorter overall survival of PDAC patients. Multivariate analysis revealed that both MALAT-1 and miR-200c-3p levels were independent prognostic factors.

Conclusion

Our findings firstly revealed a novel feedback loop between high MALAT-1 and low miR-200c-3p. Targeting the feedback loop between high MALAT-1 and low miR-200c-3p will be a therapeutic strategy for PDAC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4954-9) contains supplementary material, which is available to authorized users.

MicroRNAs as Biomarkers of B-cell Lymphoma

B-cell lymphomas represent a diverse group of neoplasms classified primarily by histopatholgy and are often challenging to accurately diagnose. Despite having been recognized less than 20 years ago, microRNAs (miRNAs) have emerged as one of the most promising class of cancer molecular biomarkers and are particularly attractive as they can be readily detected in formalin-fixed paraffin-embedded biopsy material and biological fluids such as blood. Many of the identified B-cell lymphoma miRNA biomarkers also play crucial regulatory roles in normal B-cell development. Below we consider the identity, function, and biomarker potential of miRNAs in B-cell lymphoma and most importantly the barriers that remain to be overcome if they are really to become part of routine clinical practice.

Effect of exosomal miRNA on cancer biology and clinical applications

Exosomes, extracellular vesicles with diameters ranging from 30 to 150 nm, are widely present in various body fluids. Recently, microRNAs (miRNAs) have been identified in exosomes, the biogenesis, release, and uptake of which may involve the endosomal sorting complex required for transport (ESCRT complex) and relevant proteins. After release, exosomes are taken up by neighboring or distant cells, and the miRNAs contained within modulate such processes as interfering with tumor immunity and the microenvironment, possibly facilitating tumor growth, invasion, metastasis, angiogenesis and drug resistance. Therefore, exosomal miRNAs have a significant function in regulating cancer progression. Here, we briefly review recent findings regarding tumor-derived exosomes, including RNA sorting and delivering mechanism. We then describe the intercommunication occurring between different cells via exosomal miRNAs in tumor microenvironmnt, with impacts on tumor proliferation, vascularization, metastasis and other biological characteristics. Finally, we highlight the potential role of these molecules as biomarkers in cancer diagnosis and prognosis and tumor resistance to therapeutics.

MicroRNA-598 inhibits the proliferation and invasion of non-small cell lung cancer cells by directly targeting ZEB2

An increasing number of studies have observed that microRNAs (miRNAs) are abnormally expressed in non-small cell lung cancer (NSCLC), and that their aberrant expression links with the progression and development of NSCLC. Therefore, it is necessary to full elucidate the specific roles of miRNAs in NSCLC, as this may facilitate the identification of novel therapeutic targets. In the present study, it was observed that miRNA-598 (miR-598) expression was significantly downregulated in NSCLC tissues and cell lines. Decreased miR-598 was negatively correlated with TNM stage and lymph node metastasis in NSCLC patients. In addition, ectopic expression of miR-598 reduced NSCLC cell proliferation and invasion in vitro. The zinc finger E-box-binding homeobox 2 (ZEB2) was validated as a direct target of miR-598 in NSCLC cells. ZEB2 was upregulated in NSCLC tissues and the upregulation of ZEB2 was inversely correlated with the miR-598 level. The results revealed that restored ZEB2 expression abrogated the inhibitory effects of miR-598 overexpression in NSCLC cells. In conclusion, the results of the present study revealed that miR-598 may inhibit the progression of NSCLC by directly targeting ZEB2, which suggests that this miRNA may be identified as a potential novel prognostic biomarker and therapeutic target for patients with NSCLC.

Novel circular RNA, hsa_circ_0025039 promotes cell growth, invasion and glucose metabolism in malignant melanoma via the miR-198/CDK4 axis

Malignant melanoma, a tumor derived from melanocytes, shows severe drug resistance and prompt metastasis, causing a serious threat to human health. Circular RNAs (circRNAs) are widely expressed in mammals and have been indicated to play important roles in tumorigenesis. In the present study, we analyzed the variability of circRNAs in malignant melanoma by microarray and identified six differentially expressed circRNAs. In particular, we found that hsa_circ_0025039, which is formed by FOXM1 exons, is significantly upregulated in melanoma. In vitro, the knockdown of circ_0025039 inhibited cell proliferation, colony formation ability, invasion and glucose metabolism in melanoma cells. Additionally, we identified miR-198 as a direct target of hsa_circ_0025039. Furthermore, we demonstrated that hsa_circ_0025039 regulates CDK4 expression by sponging miR-198. In vivo study indicated that the silencing of hsa_circ_0025039 inhibits melanoma tumor formation and downregulates miR-198 and CDK4 expression. Taken together, our data showed that circ_0025039 promotes cell growth, invasion and glucose metabolism in malignant melanoma by sponging miR-198 and regulating CDK4.

Upregulated hsa_circ_0004458 Contributes to Progression of Papillary Thyroid Carcinoma by Inhibition of miR-885-5p and Activation of RAC1

BACKGROUND Circular RNAs (circRNAs), a class of noncoding RNAs, may act as biomarkers and therapeutic targets of various cancers. However, the effects of hsa_circ_0004458 in papillary thyroid carcinoma (PTC) are still very much unclear. We aimed to demonstrate the potential roles of hsa_circ_0004458 in the progression of PTC. MATERIAL AND METHODS In our study, qRT-PCR assay was performed to assess hsa_circ_0004458, miR-885-5p and RAC1 expressions. Dual-luciferase reporter assay was used to detect the regulatory effects of hsa_circ_0004458 on miR-885-5p, and miR-885-5p on RAC1. MTT and flow cytometry assays were used to measure the cell proliferation, cycle, and apoptosis abilities. Tumor formation assay in nude mice was performed to measure the tumor growth in vivo. RESULTS Our results indicated that hsa_circ_0004458 was upregulated in PTC tissues and cells, while silencing of hsa_circ_0004458 suppressed PTC cell proliferation and promoted PTC cell cycle arrest and apoptosis in vitro. Tumor formation assay in nude mice showed that knockdown of hsa_circ_0004458 by siRNAs inhibited the growth of PTC tumor in vivo. In addition, we found that miR-885-5p was a direct target of hsa_circ_0004458, and silencing of hsa_circ_0004458 inhibited PTC cell proliferation by miR-885-5p. We also demonstrated that RAC1 was a direct target of miR-885-5p and silencing of RAC1 suppressed PTC cell proliferation. CONCLUSIONS We found that hsa_circ_0004458 promoted the progression of PTC by inhibition of miR-885-5p and activation of RAC1, and hsa_circ_0004458 may serve as a potential therapeutic target and biomarker for PTC.

Mesotheliomas in Genetically Engineered Mice Unravel Mechanism of Mesothelial Carcinogenesis

Malignant mesothelioma (MM), a rare and severe cancer, mainly caused as a result of past-asbestos exposure, is presently a public health concern. Current molecular studies aim to improve the outcome of the disease, providing efficient therapies based on the principles of precision medicine. To model the molecular profile of human malignant mesothelioma, animal models have been developed in rodents, wild type animals and genetically engineered mice harbouring mutations in tumour suppressor genes, especially selecting genes known to be inactivated in human malignant mesothelioma. Animals were either exposed or not exposed to asbestos or to other carcinogenic fibres, to understand the mechanism of action of fibres at the molecular level, and the role of the selected genes in mesothelial carcinogenesis. The aim of the manuscript was to compare mesothelioma models to human malignant mesothelioma and to specify the clue genes playing a role in mesothelial carcinogenesis. Collectively, MM models recapitulate the clinical features of human MM. At least two altered genes are needed to induce malignant mesothelioma in mice. Two pathways regulated by Cdkn2a and Trp53 seem independent key players in mesothelial carcinogenesis. Other genes and pathways appear as bona fide modulators of the neoplastic transformation.

MiR-663, a MicroRNA Linked with Inflammation and Cancer That Is under the Influence of Resveratrol

Resveratrol (trans-3,5,4′-trihydroxystilbene, RSV) is a non-flavonoid dietary polyphenol with antioxidant, anti-inflammatory and anti-cancer properties that is primarily found in red berries. While RSV displays many beneficial effects in vitro, its actual effects in vivo or in animal models remain passionately debated. Recent publications suggest that RSV pleiotropic effects could arise from its capability to regulate the expression and activity of microRNAs, short regulators themselves capable of regulating up to several hundreds of target genes. In particular, RSV increases microRNA miR-663 expression in different human cell lines, suggesting that at least some of its multiple beneficial properties are through the modulation of expression of this microRNA. Indeed, the expression of microRNA miR-663 is reduced in certain cancers where miR-663 is considered to act as a tumor suppressor gene, as well as in other pathologies such as cardiovascular disorders. Target of miR-663 include genes involved in tumor initiation and/or progression as well as genes involved in pathologies associated with chronic inflammation. Here, we review the direct and indirect effects of RSV on the expression of miR-663 and its target transcripts, with emphasise on TGFβ1, and their expected health benefits, and argue that elucidating the molecular effects of different classes of natural compounds on the expression of microRNAs should help to identify new therapeutic targets and design new treatments.

MiR-150 predicts survival in patients with sepsis and inhibits LPS-induced inflammatory factors and apoptosis by targeting NF-κB1 in human umbilical vein endothelial cells

MiR-150 is involved into some pathological processes, such as tumorigenesis and autoimmune diseases. However, little is known about the involvement of miR-150 in human sepsis. In this study, plasma miR-150 level had a diagnostic and independent prognostic value in patients with sepsis, and negatively correlated with renal dysfunction and 28-day survival as well as plasma levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). MiR-150 expression was also significantly decreased in human umbilical vein endothelial cells (HUVECs) and C57BL/6 mice with sepsis after lipopolysaccharides (LPS) treatment. In-vitro, miR-150 over-expression protected HUVECs from LPS-induced apoptosis and the expressions of nuclear factor-κB1 (NF-κB1), IL-6, TNF-α, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin. Furthermore, NF-κB1 was identified as a direct target of miR-150. Restored NF-κB1 expression antagonized the protective effects of miR-150, while suppression of NF-κB1 enhanced these protective effects. Our findings indicate miR-150 predicts survival in patients with sepsis and inhibits LPS-induced inflammatory factors and apoptosis by targeting NF-κB1 in human umbilical vein endothelial cells. Thus, miR-150 may be a useful biomarker or target in the diagnosis, prognosis and treatment of patients with sepsis.