Overexpression of mir-183 and mir-494 promotes proliferation and migration in human breast cancer cell lines

Investigating the interplay between the mir-183/182/96 cluster and the adherens junction pathway in early-stage breast cancer

Although the miR-183/182/96 cluster is overexpressed in breast cancer (BC), little is known about its role in the development of pre-carcinogenic lesions which harbor disrupted adherens junctions (AJ) and may promote BC. Here, we used microRNA and RNA sequencing data from The Cancer Genome Atlas (TCGA) Breast Cancer project to investigate the relationship between the miR-183/182/96 cluster and AJ signaling in early-stage BC. We found that all members of the cluster are significantly overexpressed in early-stage BC, the AJ signaling pathway is enriched for genes down-regulated in early-stage BC, and the AJ signaling pathway is enriched for experimentally validated targets of the miR-183/182/96 cluster. The expression of hsa-miR-182 correlates inversely with the mRNA expression of four of its target genes belonging to the AJ signaling pathway: WASF3, EGFR, MET, and CTNNA3. However, the correlations between hsa-miR-182 and AJ gene expression did not differ significantly between targets and non-targets of hsa-miR-182. This suggests that regulatory effects of microRNAs are less pronounced in cancer, as has been shown by other studies. Furthermore, WASF3, EGFR, and MET are oncogenes that tend to be upregulated in later BC stages, implying that the role of some AJ genes changes with different BC stages.

p27 specifically decreases in squamous carcinoma, and mediates NNK-induced transformation of human bronchial epithelial cells

Lung cancer remains the leading cause of cancer-related deaths, with cigarette smoking being the most critical factor, linked to nearly 90% of lung cancer cases. NNK, a highly carcinogenic nitrosamine found in tobacco, is implicated in the lung cancer-causing effects of cigarette smoke. Although NNK is known to mutate or activate certain oncogenes, its potential interaction with p27 in modulating these carcinogenic effects is currently unexplored. Recent studies have identified specific downregulation of p27 in human squamous cell carcinoma, in contrast to adenocarcinoma. Additionally, exposure to NNK significantly suppresses p27 expression in human bronchial epithelial cells. Subsequent studies indicates that the downregulation of p27 is pivotal in NNK-induced cell transformation. Mechanistic investigations have shown that reduced p27 expression leads to increased level of ITCH, which facilitates the degradation of Jun B protein. This degradation in turn, augments miR-494 expression and its direct regulation of JAK1 mRNA stability and protein expression, ultimately activating STAT3 and driving cell transformation. In summary, our findings reveal that: (1) the downregulation of p27 increases Jun B expression by upregulating Jun B E3 ligase ITCH, which then boosts miR-494 transcription; (2) Elevated miR-494 directly binds to 3'-UTR of JAK1 mRNA, enhancing its stability and protein expression; and (3) The JAK1/STAT3 pathway is a downstream effector of p27, mediating the oncogenic effect of NNK in lung cancer. These findings provide significant insight into understanding the participation of mechanisms underlying p27 inhibition of NNK induced lung squamous cell carcinogenic effect.

Suppression of gastric cancer cell proliferation by miR-494-3p inhibitor-loaded engineered exosomes

Background

Gastric cancer necessitates novel treatments, and exosomes are promising therapeutic carriers. We created miR-494-3p inhibitor exosomes to assess their effects on gastric cancer cells.

Methods

We conducted a comprehensive investigation into the expression of the oncogenic miR-494-3p in gastric cancer tissues from patients. Subsequently, we engineered miR-494-3p inhibitor-loaded exosomes and characterized their morphology and size through transmission electron microscopy and nanoparticle tracking analysis. We next determined the encapsulation efficiency of the miR-494-3p inhibitor within these exosomes and evaluated the exosomes' structural integrity by quantifying the presence of exosomal markers. Following these validations, we co-cultured miR-494-3p inhibitor exosomes with cancer cells and employed PKH26 staining to visualize the efficient endocytosis of engineered exosomes by gastric cancer cells and assess the impact of these modified exosomes on gastric cancer cell proliferation, apoptosis, migration, and invasion.

Results

Increased expression of miR-494-3p was observed in gastric cancer tissues as compared to controls. Significant low miR-494-3p levels were found within miR-494-3p inhibitor exosomes, signifying effective encapsulation. The incorporation of miR-494-3p inhibitor into engineered exosomes did not alter exosome morphology or size. Finally, PKH26-stained exosomes clearly demonstrated efficient endocytosis by gastric cancer cells, leading to reduced proliferation, migration, invasion, and increased apoptosis.

Conclusion

Our study identifies elevated miR-494-3p in gastric cancer tissues prompting the development of miR-494-3p inhibitor-loaded exosomes with efficient encapsulation. These engineered exosomes demonstrate successful endocytosis by cancer cells. This highlights their potential for therapeutic use in gastric cancer treatment by suppressing proliferation, migration, and invasion while enhancing apoptosis.

Mir-183 functions as an oncogene via decreasing PTEN in breast cancer cells

Regarding the important role of microRNAs in breast cancer, investigating the molecular mechanisms of miRs and their impacts on breast cancer progression is critical. Thus, the present work aimed to investigate the molecular mechanism of miR-183 in breast cancer. PTEN was validated by dual luciferase assay as a target gene of miR-183. Through qRT-PCR analysis, miR-183 and PTEN mRNA levels in breast cancer cell lines were measured. To determine the impacts of miR-183 on cell viability, the MTT assay was used. Moreover, flowcytometry was applied to analyze the effects of miR-183 on the cell cycle progression. To detect the effects of miR-183 on the migration of BC cell lines, wound healing was used along with a Trans-well migration assay. Western blot was utilized to assess the effect of miR-183 on PTEN protein expression. MiR-183 can exert an oncogenic effect by promoting cell viability, migration, and cell cycle progression. It was revealed that cellular oncogenicity is positively regulated by miR-183 by inhibiting the expression of PTEN. According to the present data, miR-183 may play a vital role in the progression of breast cancer by reducing PTEN expression. It may be also a potential therapeutic target for this disease.

The Role of Cow's Milk Consumption in Breast Cancer Initiation and Progression

PURPOSE OF REVIEW

This review evaluates cow milk's impact on breast carcinogenesis by linking recent epidemiological evidence and new insights into the molecular signaling of milk and its constituents in breast cancer (BCa) pathogenesis.

RECENT FINDINGS

Recent prospective cohort studies support the association between cow's milk consumption and the risk of estrogen receptor-α-positive (ER+) BCa. Milk is a complex biological fluid that increases systemic insulin-like growth factor 1 (IGF-1), insulin and estrogen signaling, and interacting hormonal promoters of BCa. Further potential oncogenic components of commercial milk include exosomal microRNAs (miR-148a-3p, miR-21-5p), bovine meat and milk factors, aflatoxin M1, bisphenol A, pesticides, and micro- and nanoplastics. Individuals with BRCA1 loss-of-function mutations and FTO and IGF1 gain-of-function polymorphisms enhancing IGF-1/mTORC1 signaling may be at increased risk for milk-induced ER+ BCa. Recent prospective epidemiological and pathobiochemical studies identify commercial milk consumption as a critical risk factor of ER+ BCa. Large meta-analyses gathering individuals of different ethnic origins with milk derived from dairy cows of varying genetic backgrounds and diverse feeding procedures as well as missing data on thermal processing of milk (pasteurization versus ultra-heat treatment) make multi-national meta-analyses unsuitable for BCa risk estimations in susceptible populations. Future studies are required that consider all vulnerable periods of breast carcinogenesis to cow's milk exposure, beginning during the perinatal period and puberty, since these are the most critical periods of mammary gland morphogenesis. Notwithstanding the need for better studies including detailed information on milk processing and vulnerable periods of human breast carcinogenesis, the available evidence suggests that dietary guidelines on milk consumption may have to be reconsidered.

MiRNAs Overexpression and Their Role in Breast Cancer: Implications for Cancer Therapeutics

MicroRNAs have a plethora of roles in various biological processes in the cells and most human cancers have been shown to be associated with dysregulation of the expression of miRNA genes. MiRNA biogenesis involves two alternative pathways, the canonical pathway which requires the successful cooperation of various proteins forming the miRNA-inducing silencing complex (miRISC), and the non-canonical pathway, such as the mirtrons, simtrons, or agotrons pathway, which bypasses and deviates from specific steps in the canonical pathway. Mature miRNAs are secreted from cells and circulated in the body bound to argonaute 2 (AGO2) and miRISC or transported in vesicles. These miRNAs may regulate their downstream target genes via positive or negative regulation through different molecular mechanisms. This review focuses on the role and mechanisms of miRNAs in different stages of breast cancer progression, including breast cancer stem cell formation, breast cancer initiation, invasion, and metastasis as well as angiogenesis. The design, chemical modifications, and therapeutic applications of synthetic anti-sense miRNA oligonucleotides and RNA mimics are also discussed in detail. The strategies for systemic delivery and local targeted delivery of the antisense miRNAs encompass the use of polymeric and liposomal nanoparticles, inorganic nanoparticles, extracellular vesicles, as well as viral vectors and viruslike particles (VLPs). Although several miRNAs have been identified as good candidates for the design of antisense and other synthetic modified oligonucleotides in targeting breast cancer, further efforts are still needed to study the most optimal delivery method in order to drive the research beyond preclinical studies.

Identification of new RAD51D-regulating microRNAs that also emerge as potent inhibitors of the Fanconi anemia/homologous recombination pathways

The Fanconi anemia (FA) and homologous recombination (HR) pathways, which partially overlap and include RAD51 and its paralogs, are key for the repair of different types of DNA damage, such as DNA interstrand crosslinks. First, to broadly assess the impact of microRNA-mediated regulation, we examined microRNA expression profiles in five isogenic fibroblast cell pairs, either deficient in DNA repair due to germline mutations in FANCA, FANCB, FANCC, FANCI or BRIP1/FANCJ or proficient due to correction with retroviral vectors. In each pair, we observed lower abundance of specific microRNAs in the FA-deficient cells. From the list of microRNAs, we experimentally confirmed the effects of miR-141-3p and miR-369-3p targeting RAD51B and miR-15a-5p, miR-494-3p as well as miR-544a targeting RAD51D. However, by western blotting, only RAD51D protein was reduced by a mixture of its regulating microRNAs. Gene ontology analyses and identification of additional FA/HR factors as targets of miR-15a-5p, miR-494-3p and miR-544a strongly suggested the widespread influence of these microRNAs on HR. Interestingly, only miR-494-3p directly reduced RAD51 foci formation, while a mixture of miR-15a-5p, miR-494-3p and miR-544a strongly reduced HR activity in green fluorescent protein (GFP) repair assays. In summary, by successfully employing this novel loss- and gain-of-function strategy, we have identified new microRNAs strongly inhibiting HR in mammalian cells. Understanding and modulating such miRNA regulation of DNA repair genes/pathways might help to overcome the reduced repair capacity of FA patients with biallelic hypomorphic mutations or help to engineer synthetic lethality strategies for patients with mutations in cancer-associated FA/HR genes.

Circular RNA-associated ceRNA network involved in HIF-1 signalling in triple-negative breast cancer: circ_0047303 as a potential key regulator

The aggressive and highly metastatic nature of triple‐negative breast cancer (TNBC) causes patients to suffer from the poor outcome. HIF‐1 signalling pathway is a prominent pathway that contributes to angiogenesis and metastasis progression in tumours. On the contrary, the undeniable importance of circular RNAs (circRNAs) as multifunctional non‐coding RNAs (ncRNAs) has been identified in breast cancer. These ncRNAs owing to their high stability and specificity have been becoming a hotspot in cancer researches. circRNAs act as competing endogenous RNAs (ceRNAs) and compete with mRNAs for shared miRNAs, thus modulate gene expression. Since the most dysregulated biological functions in TNBC are associated with cellular invasion, understanding the molecular pathogenesis of these processes is a crucial step towards the development of new treatment approaches. The purpose of this study is to undermine the circRNA‐associated ceRNA network involved in HIF‐1 signalling in TNBC using an integrative bioinformatics approach. In the next step, the novel circ_0047303‐mediated ceRNA regulatory axes have been extracted and validated across TNBC samples. We show that circ_0047303 has the highest degree in the circRNA‐associated ceRNA network and shows a significant up‐expression in TNBC. Moreover, our results suggest that circ_0047303 could mediate the upregulation of key angiogenesis‐related genes, including HIF‐1, EIF4E2 and VEGFA in TNBC through sponging the tumour‐suppressive miRNAs. The circ_0047303 could be a promising molecular biomarker and/or therapeutic target for TNBC.

Epigenetics effect on pathogenesis of thyroid-associated ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is an autoimmune disease. Recent studies have found the aberrant epigenetics in TAO, including DNA methylation, non-coding RNAs, and histone modification. Many genes have an aberrant level of methylation in TAO. For example, higher levels are found in CD14, MBP, ANGLE1, LYAR and lower levels in DRD4 and BOLL. Non-coding RNAs are involved in the immune response (miR-146a, miR-155, miR-96, miR-183), fibrosis regulation (miR-146a, miR-21, miR-29), adipogenesis (miR-27) and are thought to play roles in TAO. MicroRNA is also related to the clinical activity score (miR-Let7d-5p) and may be a predictor of glucocorticoid therapy (miR-224-5p). The quantities of H4 in TAO are increased compared with euthyroid control subjects, and the role of histone modifications in Graves' disease may lead to better understanding of its role in TAO. More studies are needed to explain the role of epigenetics in TAO and provide potential therapeutic strategies.

A Comprehensive Analysis of Northern versus Liquid Hybridization Assays for mRNAs, Small RNAs, and miRNAs Using a Non-Radiolabeled Approach

Northern blotting (NB), a gold standard for RNA detection, has lost its charm due to its hands-on nature, need for good quality RNA, and radioactivity. With the emergence of the field of microRNAs (miRNAs), the necessity for sensitive and quantitative NBs has again emerged. Here, we developed highly sensitive yet non-radiolabeled, fast, economical NB, and liquid hybridization (LH) assays without radioactivity or specialized reagents like locked nucleic acid (LNA)- or digoxigenin-labeled probes for mRNAs/small RNAs, especially miRNAs using biotinylated probes. An improvised means of hybridizing oligo probes along with efficient transfer, cross-linking, and signal enhancement techniques was employed. Important caveats of each assay were elaborated upon, especially issues related to probe biotinylation, use of exonuclease, and bioimagers not reported earlier. We demonstrate that, while the NBs were sensitive for mRNAs and small RNAs, our LH protocol could efficiently detect these and miRNAs using less than 10-100 times the total amount of RNA, a sensitivity comparable to radiolabeled probes. Compared to NBs, LH was a faster, more sensitive, and specific approach for mRNA/small RNA/miRNA detection. A comparison of present work with six seminal studies is presented along with detailed protocols for easy reproducibility. Overall, our study provides effective platforms to study large and small RNAs in a sensitive, efficient, and cost-effective manner.

Combinatorial Effect of DCA and Let-7a on Triple-Negative MDA-MB-231 Cells: A Metabolic Approach of Treatment

Dichloroacetate (DCA) is a metabolic modulator that inhibits pyruvate dehydrogenase activity and promotes the influx of pyruvate into the tricarboxylic acid cycle for complete oxidation of glucose. DCA stimulates oxidative phosphorylation (OXPHOS) more than glycolysis by altering the morphology of the mitochondria and supports mitochondrial apoptosis. As a consequence, DCA induces apoptosis in cancer cells and inhibits the proliferation of cancer cells. Recently, the role of miRNAs has been reported in regulating gene expression at the transcriptional level and also in reprogramming energy metabolism. In this article, we indicate that DCA treatment leads to the upregulation of let-7a expression, but DCA-induced cancer cell death is independent of let-7a. We observed that the combined effect of DCA and let-7a induces apoptosis, reduces reactive oxygen species generation and autophagy, and stimulates mitochondrial biogenesis. This was later accompanied by stimulation of OXPHOS in combined treatment and was thus involved in metabolic reprogramming of MDA-MB-231 cells.

Gene expression patterns associated with tumor-infiltrating CD4+ and CD8+ T cells in invasive breast carcinomas

BACKGROUND

Breast carcinoma is one of the most common tumors in women. The immune microenvironment, especially T cell infiltration, is related to the occurrence and prognosis of breast carcinoma.

OBJECTIVE

This study investigated the gene expression patterns associated with tumor-infiltrating CD4+ and CD8+ T cells in invasive breast carcinomas.

METHODS

The gene expression data and corresponding clinical phenotype data from the Cancer Genome Atlas Breast Invasive Carcinoma (TCGA-BRCA) were downloaded. The stromal and immune score were calculated using ESTIMATE. The differentially expressed genes (DEGs) with a high vs. low stromal score and a high vs. low immune score were screened and then functionally enriched. The tumor-infiltrating immune cells were investigated using the Cibersort algorithm, and the CD4+ and CD8+ T cell-related genes were identified using a Spearman correlation test of infiltrating abundance with the DEGs. Moreover, the miRNA-mRNA pairs and lncRNA-miRNA pairs were predicted to construct the competing endogenous RNAs (ceRNA) network. Kaplan-Meier (K-M) survival curves were also plotted.

RESULTS

In total, 478 DEGs with a high vs. low stromal score and 796 DEGs with a high vs. low immune score were identified. In addition, 39 CD4+ T cell-related genes and 78 CD8+ T cell-related genes were identified; of these, 14 genes were significantly associated with the prognosis of BRCA patients. Moreover, for CD4+ T cell-related genes, the chr22-38_28785274-29006793.1-miR-34a/c-5p-CAPN6 axis was identified from the ceRNA network, whereas the chr22-38_28785274-29006793.1-miR-494-3p-SLC9A7 axis was identified for CD8+ T cell-related genes.

CONCLUSIONS

The chr22-38_28785274-29006793.1-miR-34a/c-5p-CAPN6 axis and the chr22-38_28785274-29006793.1-miR-494-3p-SLC9A7 axis might regulate cellular activities associated with CD4+ and CD8+ T cell infiltration, respectively, in BRCA.

Integrated analysis of mRNA and miRNA profiles revealed the role of miR-193 and miR-210 as potential regulatory biomarkers in different molecular subtypes of breast cancer

BACKGROUND

Breast cancer is the most frequently diagnosed malignancy among women. However, the role of microRNA (miRNA) expression in breast cancer progression is not fully understood. In this study we examined predictive interactions between differentially expressed miRNAs and mRNAs in breast cancer cell lines representative of the common molecular subtypes. Integrative bioinformatics analysis identified miR-193 and miR-210 as potential regulatory biomarkers of mRNA in breast cancer. Several recent studies have investigated these miRNAs in a broad range of tumors, but the mechanism of their involvement in cancer progression has not previously been investigated.

METHODS

The miRNA-mRNA interactions in breast cancer cell lines were identified by parallel expression analysis and miRNA target prediction programs. The expression profiles of mRNA and miRNAs from luminal (MCF-7, MCF-7/AZ and T47D), HER2 (BT20 and SK-BR3) and triple negative subtypes (Hs578T e MDA-MB-231) could be clearly separated by unsupervised analysis using HB4A cell line as a control. Breast cancer miRNA data from TCGA patients were grouped according to molecular subtypes and then used to validate these findings. Expression of miR-193 and miR-210 was investigated by miRNA transient silencing assays using the MCF7, BT20 and MDA-MB-231 cell lines. Functional studies included, xCELLigence system, ApoTox-Glo triplex assay, flow cytometry and transwell inserts were performed to determine cell proliferation, cytotoxicity, apoptosis, migration and invasion, respectively.

RESULTS

The most evident effects were associated with cell proliferation after miR-210 silencing in triple negative subtype cell line MDA-MB-231. Using in silico prediction algorithms, TNFRSF10 was identified as one of the potential regulated downstream targets for both miRNAs. The TNFRSF10C and TNFRSF10D mRNA expression inversely correlated with the expression levels of miR-193 and miR210 in breast cell lines and breast cancer patients, respectively. Other potential regulated genes whose expression also inversely correlated with both miRNAs were CCND1, a known mediator on invasion and metastasis, and the tumor suppressor gene RUNX3.

CONCLUSIONS

In summary, our findings identify miR-193 and miR-210 as potential regulatory miRNA in different molecular subtypes of breast cancer and suggest that miR-210 may have a specific role in MDA-MB-231 proliferation. Our results highlight important new downstream regulated targets that may serve as promising therapeutic pathways for aggressive breast cancers.

Construction of a Potential Breast Cancer-Related miRNA-mRNA Regulatory Network

Background

Breast cancer is a malignant tumor that occurs in the epithelial tissue of the breast gland and has become the most common malignancy in women. The regulation of the expression of related genes by microRNA (miRNA) plays an important role in breast cancer. We constructed a comprehensive breast cancer-miRNA-gene interaction map.

Methods

Three miRNA microarray datasets (GSE26659, GSE45666, and GSE58210) were obtained from the GEO database. Then, the R software “LIMMA” package was used to identify differential expression analysis. Potential transcription factors and target genes of screened differentially expressed miRNAs (DE-miRNAs) were predicted. The BRCA GE-mRNA datasets (GSE109169 and GSE139038) were downloaded from the GEO database for identifying differentially expressed genes (DE-genes). Next, GO annotation and KEGG pathway enrichment analysis were conducted. A PPI network was then established, and hub genes were identified via Cytoscape software. The expression and prognostic roles of hub genes were further evaluated.

Results

We found 6 upregulated differentially expressed- (DE-) miRNAs and 18 downregulated DE-miRNAs by analyzing 3 Gene Expression Omnibus databases, and we predicted the upstream transcription factors and downstream target genes for these DE-miRNAs. Then, we used the GEO database to perform differential analysis on breast cancer mRNA and obtained differentially expressed mRNA. We found 10 hub genes of upregulated DE-miRNAs and 10 hub genes of downregulated DE-miRNAs through interaction analysis.

Conclusions

In this study, we have performed an integrated bioinformatics analysis to construct a more comprehensive BRCA-miRNA-gene network and provide new targets and research directions for the treatment and prognosis of BRCA.

miR-155, miR-191, and miR-494 as diagnostic biomarkers for oral squamous cell carcinoma and the effects of Avastin on these biomarkers

Objectives

Oral squamous cell carcinoma (OSCC) is one of the most common types of head and neck cancer. MicroRNAs, as new biomarkers, are recommended for diagnosis and treatment of different types of cancers. Bevacizumab, sold under the trade name Avastin, is a humanized whole monoclonal antibody that targets and blocks VEGF-A (vascular endothelial growth factor A; angiogenesis) and oncogenic signaling pathways.

Materials and Methods

This study comprised 50 cases suffering from OSCC and 50 healthy participants. Peripheral blood samples were collected in glass test tubes, and RNA extraction was started immediately. Expression levels of miR-155, miR-191, and miR-494 biomarkers in the peripheral blood of OSCC-affected individuals and healthy volunteers in vivo were evaluated using real-time PCR. The influence of Avastin on the expression levels of the aforementioned biomarkers in vitro and in the HN5 cell line was also investigated.

Results

Expression levels of miR-155, miR-191, and miR-494 in the peripheral blood of individuals affected by OSCC were higher than in those who were healthy. Moreover, Avastin at a concentration of 400 µM caused a decrease in the expression levels of the three biomarkers and a 1.5-fold, 3.5-fold, and 4-fold increase in apoptosis in the test samples compared to the controls in the HN5 cell line after 24, 48, and 72 hours, respectively.

Conclusion

The findings of this study demonstrate that overexpression of miR-155, miR-191, and miR-494 is associated with OSCC, and Avastin is able to regulate and downregulate the expression of those biomarkers and increase apoptosis in cancerous cells in the HN5 cell line

Exosomes: Insights from Retinoblastoma and Other Eye Cancers

Exosomes, considered as cell debris or garbage bags, have been later characterized as nanometer-sized extracellular double-membrane lipid bilayer bio-vesicles secreted by the fusion of vesicular bodies with the plasma membrane. The constituents and the rate of exosomes formation differ in different pathophysiological conditions. Exosomes are also observed and studied in different parts of the eye, like the retina, cornea, aqueous, and vitreous humor. Tear fluid consists of exosomes that are shown to regulate various cellular processes. The role of exosomes in eye cancers, especially retinoblastoma (RB), is not well explored, although few studies point towards their presence. Retinoblastoma is an intraocular tumor that constitutes 3% of cases of cancer in children. Diagnosis of RB may require invasive procedures, which might lead to the spread of the disease to other parts. Due to this reason, better ways of diagnosis are being explored. Studies on the exosomes in RB tumors and serum might help designing better diagnostic approaches for RB. In this article, we reviewed studies on exosomes in the eye, with a special emphasis on RB. We also reviewed miRNAs expressed in RB tumor, serum, and cell lines and analyzed the targets of these miRNAs from the proteins identified in the RB tumor exosomes. hsa-miR-494 and hsa-miR-9, upregulated and downregulated, respectively in RB, have the maximum number of targets. Although oppositely regulated, they share the same targets in the proteins identified in RB tumor exosomes. Overall this review provides the up-to-date progress in the area of eye exosome research, with an emphasis on RB.

Integrative bioinformatics analysis reveals miR-494 and its target genes as predictive biomarkers of trastuzumab-resistant breast cancer

Background

The focus of trastuzumab resistance biomarkers in recent decades has been on epigenetic and non-coding RNA-based mechanisms. In this study, the potential of miR-494 and its target genes as predictive biomarkers for breast cancer (BC) resistance to trastuzumab was identified. The microarray data were obtained from the GEO database, including GSE101841, GSE75669, and GSE66305. Data processing was conducted using GEO2R to obtain differentially expressed genes (DEGs).

Results

The data analysis using GEO2R revealed that DEGs from GSE101841 and GSE75669 consisted of 3 and 135 upregulated miRNAs, respectively. On the other hand, the same analysis revealed 8 and 226 downregulated miRNAs for DEGs from GSE101841 and GSE75669, respectively. A Venn diagram showed that one miR was detectable in serum and tissue samples, namely miR-494. The miR-494 target was predicted using the miRecords database and resulted in 69 target genes. A Venn diagram between miR-494 target genes from miRecords and the mRNA array from GSE66305 revealed three potential targets of CNR1, RBM39, and ZNF207. A Kaplan–Meier survival plot showed that BC patients with a high miR-494 level and a low ZNF207 mRNA level had significantly worse overall survival. Validation of target genes in BC samples and trastuzumab-resistant and -sensitive BC cells with GEPIA and ONCOMINE highlighted the potential of CNR1, RBM39, and ZNF207 as predictive biomarkers of trastuzumab resistance in BC cells.

Conclusion

Taken together, these results suggest that miR-494 plays a role in the mechanism of BC resistance to trastuzumab by involving its target genes CNR1, RBM39, and ZNF207.

The ability of miRNAs to induce mesenchymal-to-epithelial transition (MET) in cancer cells is highly dependent upon genetic background

Understanding of the molecular basis of host cell-miRNA interactions is prerequisite to the successful application of miRNAs as potential therapeutic agents. We studied the morphological and molecular consequences of over expression of three sequence divergent miRNAs previously implicated in the mesenchymal-to-epithelial transition process (MET) in three distinct mesenchymal-like cancer cell lines. The ability of miRNAs to induce morphological changes characteristic of MET positively correlated with induced changes in the expression of genes previously implicated in the process. Variability in the responses of different mesenchymal-like cells to over expression of the same miRNAs was attributable to inherent differences in trans-regulatory profiles pre-disposing these cells to miRNA-induced MET. Collectively our results indicate that miRNA-mediated regulation of MET is a highly integrated process that is significantly modulated by the molecular background of individual cells.

MicroRNA-183 regulates lipopolysaccharide-induced oxidative stress of hippocampal neurons by targeting the fibronectin 1 gene

Oxidative stress is implicated in the initiation and progression of human and animal diseases. MicroRNA (MiR) has been reported to be involved in the body's regulation to oxidative stress. We investigated if miR-183 regulates lipopolysaccharide (LPS)-induced oxidative stress in the hippocampus of weaned piglets. LPS-treated piglets had lower expression of miR-183 and higher expression of the fibronectin(FN)1 gene in their hippocampus than control piglets. The expression profiles of miR-183 and the FN1 gene in primary cultured rat hippocampal neurons exposed to LPS were consistent with those in the hippocampus of LPS-treated piglets. The LPS-induced expression of FN1 was reversed in hippocampal neurons by transfection with an miR-183 mimic. A luciferase reporter assay further demonstrated that the FN1 gene is a direct target of miR-183. Taken together, our results demonstrated that miR-183 regulates LPS-induced oxidative stress at least in part by targeting FN1.

MicroRNA-590-3p inhibits invasion and metastasis in triple-negative breast cancer by targeting Slug

miR-590-3p acts as a tumor suppressor in glioblastoma multiform, medulloblastoma, hepatocellular carcinoma, and nephroblastoma. Here, we studied the role of miR-590-3p in triple-negative breast cancer (TNBC). The miR-590-3p levels in TNBC specimens were significantly lower than those in non-TNBC specimens. Overexpression of miR-590-3p significantly inhibited migration and invasion of TNBC cells and lung metastasis in vivo. Interestingly, miR-590-3p decreased the Slug mRNA and protein levels in TNBC cells, and luciferase reporter assay showed that miR-590-3p directly targeted 3'-UTR of Slug in TNBC cells. Importantly, overexpression of Slug reversed the inhibitory effect of miR-590-3p on migration and invasion of TNBC cells. Taken together, miR-590-3p inhibits TNBC migration and invasion by directly targeting Slug, suggesting a potential therapeutic effect of miR-590-3p for TNBC.

OTUD6B-AS1 Inhibits Viability, Migration, and Invasion of Thyroid Carcinoma by Targeting miR-183-5p and miR-21

Background: The long noncoding RNA (lncRNA) functions as a regulator of initiation, progression, and metastasis of thyroid carcinomas. lncRNA OTUD6B antisense RNA 1 (OTUD6B-AS1) is a tumor-suppressive noncoding RNA in clear cell renal cell carcinoma. The role of OTUD6B-AS1 in thyroid carcinomas has not been reported yet. We aim to investigate the expression and biological functions of OTUD6B-AS1 in thyroid carcinomas. Methods: The expression level of OTUD6B-AS1 was measured in 60 paired human thyroid carcinoma tissues and corresponding adjacent normal thyroid tissues. The correlations between the OTUD6B-AS1 expression levels and clinicopathological features were evaluated using the Mann-Whitney test. The effects of OTUD6B-AS1 on thyroid carcinoma cells were determined via the MTT and transwell assays. The potential targets of OTUD6B-AS1 were screened using the online programs OncomiR and StarBase 3.0, and the LncBase Predicted v.2. Luciferase reporter assay was used to confirm the interactions between OTUD6B-AS1 and its potential targets. Results: OTUD6B-AS1 was downregulated in thyroid carcinoma tissue samples. The expression of OTUD6B-AS1 correlated with tumor size, clinical stage, and lymphatic metastasis of thyroid carcinoma. Overexpression of OTUD6B-AS1 significantly decreased the viability, migration, and invasion of thyroid carcinoma cells. Online programs predicted miR-183-5p and miR-21 as potential targets of OTUD6B-AS1. Luciferase reporter assays showed miR-183-5p and miR-21 bound to OTUD6B-AS1. Moreover, overexpression of miR-183-5p and miR-21 compromised the inhibitory effects of OTUD6B-AS1 on viability, migration, and invasion of thyroid carcinoma cells. Conclusions: Taken together, our findings present in vitro evidence of lncRNA OTUD6B-AS1 as a tumor suppressor in thyroid carcinomas. OTUD6B-AS1 inhibits viability, migration, and invasion of thyroid carcinoma by targeting miR-183-5p and miR-21.

MicroRNA-183 in Cancer Progression

MicroRNA-183(miR-183) is abnormally expressed in many kinds of tumors. It participates in the initiation and development of tumors. There are many pathways regulate the expression of miR-183. The action mechanism of miR-183 in cancer is very extensive, and contradictory conclusions are often drawn. It was upregulated in 18 kinds of cancer, downregulated in 6 kinds of cancer. In addition, there are seven types of cancer, both upregulated and downregulated reports can be found. Evidence showed that miR-183 can not only directly play the role of oncogene or antioncogene, but also regulate the expression of other oncogene or antioncogene in different cancer types. In this review, we discuss the regulator of miR-183 and summarized the expression of miR-183 in different cancers. We also counted the target genes of miR-183 and the functional roles they play. Furthermore, we focused on the roles of miR-183 in cell migration, cell invasion, epithelial-mesenchymal transition (EMT) and microangiogenesis, which play the most important roles in cancer processes. It sheds light on the likely reasons why miR-183 plays different roles in various cancers. In addition, miR-183 and its downstream effectors have the potential to be promising prognostic markers and therapeutic targets in cancer.

Chronic Hexavalent Chromium Exposure Induces Cancer Stem Cell-Like Property and Tumorigenesis by Increasing c-Myc Expression

Hexavalent chromium [Cr(VI)] is one of the most common environmental carcinogen causing lung cancer in humans; however, the mechanism of Cr(VI) carcinogenesis remains elusive. Cancer stem cells (CSCs) are considered as cancer initiating and maintaining cells. Ours and other recent studies showed that chronic Cr(VI) exposure induces CSC-like property representing an important mechanism of Cr(VI) carcinogenesis. However, how Cr(VI) exposure induces CSC-like property remains largely unknown. In this study, we found that stably knocking down the expression of c-Myc, a proto-oncogene and one of key stemness factors playing critical roles in cancer initiation and progression, in Cr(VI)-transformed human bronchial epithelial cells [BEAS-2B-Cr(VI)] significantly decreased their CSC-like property and tumorigenicity in mice. Moreover, stably knocking down c-Myc expression in parental nontransformed BEAS-2B cells significantly impaired the capability of chronic Cr(VI) exposure to induce CSC-like property and cell transformation. It was also found that stably overexpressing c-Myc alone in parental nontransformed BEAS-2B cells is capable of causing CSC-like property and cell transformation. Mechanistic studies showed that chronic Cr(VI) exposure increases c-Myc expression by down-regulating the level of microRNA-494 (miR-494). It was further determined that overexpressing miR-494 significantly reduces Cr(VI)-induced CSC-like property, cell transformation, and tumorigenesis mainly through down-regulating c-Myc expression. Together, these findings indicate that chronic low dose Cr(VI) exposure induces CSC-like property and tumorigenesis by increasing c-Myc expression through down-regulating the level of miR-494, revealing an important role of the proto-oncogene c-Myc in Cr(VI) carcinogenesis.

Chronic Hexavalent Chromium Exposure Induces Cancer Stem Cell-Like Property and Tumorigenesis by Increasing c-Myc Expression

Hexavalent chromium [Cr(VI)] is one of the most common environmental carcinogen causing lung cancer in humans; however, the mechanism of Cr(VI) carcinogenesis remains elusive. Cancer stem cells (CSCs) are considered as cancer initiating and maintaining cells. Ours and other recent studies showed that chronic Cr(VI) exposure induces CSC-like property representing an important mechanism of Cr(VI) carcinogenesis. However, how Cr(VI) exposure induces CSC-like property remains largely unknown. In this study, we found that stably knocking down the expression of c-Myc, a proto-oncogene and one of key stemness factors playing critical roles in cancer initiation and progression, in Cr(VI)-transformed human bronchial epithelial cells [BEAS-2B-Cr(VI)] significantly decreased their CSC-like property and tumorigenicity in mice. Moreover, stably knocking down c-Myc expression in parental nontransformed BEAS-2B cells significantly impaired the capability of chronic Cr(VI) exposure to induce CSC-like property and cell transformation. It was also found that stably overexpressing c-Myc alone in parental nontransformed BEAS-2B cells is capable of causing CSC-like property and cell transformation. Mechanistic studies showed that chronic Cr(VI) exposure increases c-Myc expression by down-regulating the level of microRNA-494 (miR-494). It was further determined that overexpressing miR-494 significantly reduces Cr(VI)-induced CSC-like property, cell transformation, and tumorigenesis mainly through down-regulating c-Myc expression. Together, these findings indicate that chronic low dose Cr(VI) exposure induces CSC-like property and tumorigenesis by increasing c-Myc expression through down-regulating the level of miR-494, revealing an important role of the proto-oncogene c-Myc in Cr(VI) carcinogenesis.

miRNA‑183‑5p.1 promotes the migration and invasion of gastric cancer AGS cells by targeting TPM1

MicroRNA-183 (miR-183) is a small, non-coding RNA that is involved in post-transcriptional processes, is upregulated in gastric cancer and acts as an oncogene in cancer migration. Although fragmentary reports have demonstrated the importance of miR-183 in gastric cancer, its biofunctions and regulatory effects are still unknown. In the present study, the gene and protein expression levels were determined by reverse transcription-quantitative PCR and western blot analysis. The connection between miR-183-5p.1 and tropomyosin 1 (TPM1) was tested through luciferase reporter experiments. Cell viability, apoptosis and related proteins were detected by MTT assay, flow cytometry, immunofluorescence and western blotting, respectively. The migration and invasion of AGS cells modulated by miR-183-5p.1 were analyzed by Transwell assay. TPM1 expression was found to be decreased in gastric cancer tissues and cell lines when compared with normal and adjacent tissues and gastric epithelial cells, and was regulated by miR-183-5p.1 targeting TPM1. miR-183-5p.1 overexpression facilitated the growth and suppressed the death of AGS cells through Bcl-2 and P53 proteins. In addition, miR-183-5p.1 restricted TPM1, TPM2 and TPM3 protein expression in AGS cells. The excessive levels of miR-183-5p.1 promoted the migration and invasion of AGS cells, and inhibited the apoptosis of AGS cells. However, the knockdown of miR-183-5p.1 induced the opposite in AGS cells. In conclusion, miR-183-5p.1 promotes cell proliferation, migration and invasion by downregulating TPM1 and deactivating the Bcl-2/P53 signaling pathways in gastric cancer, indicating that miR-183-5p.1 and TPM1 may be potential targets for the diagnosis or therapy of gastric cancer in the future.

miRNA expression changes during the course of neoadjuvant bevacizumab and chemotherapy treatment in breast cancer

One of the hallmarks of cancer is sustained angiogenesis. Favorable results have been reported in some breast cancer (BC) patients receiving antiangiogenic therapy with bevacizumab (Bev) in combination with chemotherapy, and further knowledge on how Bev can be optimally combined with conventional treatment to increase efficacy is strongly needed. In this randomized, neoadjuvant phase II clinical trial, 132 patients with HER2-negative, nonmetastatic BC were treated with Bev in combination with sequential chemotherapy. Biopsies were sampled before treatment, after 12 weeks with anthracycline and after taxane therapy at week 25. MicroRNA (miRNA) expression profiling was performed on biopsies from each time point. Altogether, 241 biopsies were analyzed with the aim of identifying miRNA-based biomarkers of response to therapy. Results from the miRNA analyses were reported for the ER-positive cohort, which were previously demonstrated to benefit from antiangiogenic therapy in this study. For both treatment arms of this cohort, significantly different expression was observed for 217 miRNAs between objective responding and nonresponding patients before treatment initiation. These miRNAs have been linked to regulation of epithelial-mesenchymal transition, metastasis, and tumor growth, among other processes. Bev in combination with chemotherapy resulted in similar miRNA changes to chemotherapy alone. However, the deregulation of miRNA expression occurred earlier in the Bev arm. In both arms, tumor suppressor miRNAs were found upregulated after treatment, while oncogenic miRNAs were downregulated in the Bev arm. Patients responding to Bev showed a strong correlation between deregulated miRNAs and decreased proliferation score during the course of treatment, with downregulation of miR-4465 as the strongest indicator of reduced proliferation. Integrative analyses at miRNA-, gene-, and protein expression further indicated a longitudinal decrease in proliferation. Altogether, the results indicate that proliferation might represent a predictive factor for increased Bev sensitivity, which may aid in the identification of patients who could potentially benefit from Bev.

The better effects of microbubble ultrasound transfection of miR-940 on cell proliferation inhibition and apoptosis promotion in human cervical cancer cells

Purpose

Cervical cancer is the second leading cause of women’s cancer-related death. MiR-940 has been reported as a critical factor in various cancers. Based on the high transfection efficiency and low side effect, the clinical application of microbubble ultrasound contrast agent in gene treatment has attracted a widespread attention. In this study, we determined the mechanism of miR-940 inhibiting cell proliferation and cycle procession, and promoting cell apoptosis in cervical cancer Hela cells. In addition, we compared the effects of different transfection methods, including liposome, microbubble, ultrasound, and microbubble coupled with ultrasound.

Patients and methods

MTT assay, PI staining, and Annexin-Ⅴ/PI staining assays were, respectively, performed to evaluate cell proliferation status, cell cycle progression, and apoptosis status. RT-PCR and Western blot were conducted to measure the levels of cell cycle- and apoptosis-related factors, and the phosphorylation levels of PI3K and Akt.

Results

Results showed that the overexpression of miR-940 inhibited cell proliferation, blocked cell cycle, and promoted apoptosis by regulating cell cycle-related factors (such as inhibited Cyclin D1 and CDK4) and apoptosis-related factors (such as promoted Puma and Bax, inhibited Bcl-2 and Cleaved caspase9), and inhibiting the phosphorylation and activation of PI3K/AKT pathway. Among all of them, miR-940 transfected with microbubble and ultrasound showed the greatest changes.

Conclusion

It provides evidence that miR-940 could be a wonderful biomarker and treatment agent for cervical cancer, and microbubble ultrasound would have more wide application in the clinical treatment of cancers.

MiR-486-5p inhibits IL-22-induced epithelial-mesenchymal transition of breast cancer cell by repressing Dock1

Epithelial-mesenchymal transition (EMT) is one of important steps that lead to cancer metastasis. Interleukin-22 (IL-22) is a T helper 17 (Th17) cells-secreted cytokine, it can promote invasion and metastasis of many cancers. MiR-486-5p is a microRNA that known to function as a tumor suppressor, and bioinformatics analysis predicts that Dock-1 has a binding site of miR-486-5p. In current research, we examined the relative expression levels of miR-486-5p and Dock-1 in 80 pairs of breast cancer tissues and corresponding adjacent normal tissues, also the effects of modifying their levels in cultured cells. We illustrated that IL-22 and Dock1 promote the invasion, metastasis, and EMT of breast cancer using Transwell invasion assay, western blot and immunofluorescence. MiR-486-5p directly bound the Dock1 mRNA 3' untranslated region and inhibited IL-22-induced EMT of breast cancer cells via the Dock1/NF-κB/Snail signaling pathway. Dock1 overexpression reversed the effect caused by the overexpression of miR-486-5p. Overexpression of miR-486-5p or downregulation of Dock1 reduced pulmonary metastasis in mice. This study provided insight into a potential mechanism where miRNAs regulate breast cancer metastasis and provided a novel therapeutic target for breast cancer treatment.

MiR-183 affects biological behaviors of gastric cancer SGC-7901 cells by regulating the Wnt/β-catenin signaling pathway

BACKGROUND

MiR-183 is lowly expressed in various tumor tissues such as gastric cancer, breast cancer, and bladder cancer, and plays a role as a tumor suppressor gene. However, its mechanism of action in gastric cancer is still not fully understood. Studies have shown that miR-183 can inhibit the growth, migration, and invasion of osteosarcoma cells by regulating the Wnt/β-catenin signaling pathway, and the high activation of the Wnt/β-catenin signaling pathway is closely related to the occurrence and metastasis of gastric cancer. However, it is still unclear whether miR-183 affects the biological behaviors of gastric cancer cells by regulating the Wnt/β-catenin signaling pathway.

AIM

To investigate the effect of miR-183 on the biological behaviors of gastric cancer cells and the possible mechanism involved.

METHODS

qRT-PCR was used to detect the expression of miR-183 in different gastric cancer cell lines. After gastric cancer SGC-7901 cells were transfected with miR-183 mimic or miR-NC, the transfection efficiency was detected by qRT-PCR, the proliferation of SGC-7901 cells was detected by MTT proliferation assay, the apoptosis of SGC-7901 cells was detected by flow cytometry, and the invasion and migration of SGC-7901 cells were detected by Transwell assay. Western blot was used to detect the expression of apoptosis-related and Wnt/β-catenin signaling pathway-related proteins. The SRC-7901 cells overexpressing miR-183 were treated with Wnt/β-catenin signaling pathway agonist lithium chloride to observe the changes in biological behaviors of SGC-7901 cells.

RESULTS

Compared with normal gastric mucosal epithelial GES-1 cells, the expression of miR-183 was significantly decreased in the four gastric cancer cell lines (P < 0.05). The expression level of miR-183 was significantly increased in SGC-7901 cells transfected with miR-183 mimic (P < 0.05). After overexpression of miR-183, the proliferation of SGC-7901 cells decreased (P < 0.05), the apoptosis rate and the protein expression of Bax and cleaved Caspase-3 increased (P < 0.05), and cell migration and invasion decreased (P < 0.05). The expression levels of β-catenin, p-GSK-3β, and cyclin D1 proteins were down-regulated (P < 0.05), and the expression level of GSK-3β protein was up-regulated (P < 0.05). Activation of the Wnt/β-catenin signaling pathway partially reversed the inhibitory effect of miR-183 overexpression on the proliferation, invasion, and migration of SGC-7901 cells and the promotive effect on cell apoptosis (P < 0.05).

CONCLUSION

MiR-183 inhibits the proliferation, invasion, and migration of human gastric cancer SGC-7901 cells and promotes cell apoptosis possibly by inhibiting the Wnt/β-catenin signaling pathway.

Plasma-derived exosomal miR-183 associates with protein kinase activity and may serve as a novel predictive biomarker of myocardial ischemic injury

Myocardial infarction (MI) is primarily caused by ischemic heart or coronary artery disease and is a major cause of mortality worldwide. Thus, it is necessary to establish reliable biochemical markers for the early diagnosis of MI. MicroRNAs (miRNAs or miR) have been demonstrated to circulate in biological fluids and are enclosed in extracellular vesicles, including exosomes. The current study assessed the differential expression of exosomal miRNAs in the plasma of patients with MI and healthy individuals, and the possible mechanism involved. Plasma-derived exosomes were isolated from patients with MI and healthy control individuals, and vesicles with a membrane were observed using transmission electron microscopy. Furthermore, an exosomal miRNA expression profile was compared between patients with MI and healthy individuals using a miRNA microarray. Significantly differentially expressed miRNAs were validated using reverse transcription-quantitative polymerase chain reaction. To the best of our knowledge, the present study was the first to demonstrate that miR-183 was markedly upregulated in patients with MI compared with healthy individuals. In addition, the relative exosomal miR-183 level increased with the degree of myocardial ischemic injury. Additionally, GO and KEGG analyses demonstrated that miR-183 is primarily involved in cell communication, protein kinase activity regulation and adrenergic signaling in cardiomyocytes. Furthermore, a protein-protein interaction network of all the miR-183 target genes was constructed. The results demonstrated that five core genes (PPP2CB, PPP2CA, PRKCA, PPP2CA, PPP2R5C and PPP2R2A) in the PPI network were also associated with protein kinase activity regulation and adrenergic signaling in cardiomyocytes. Taken together, these data demonstrate that exosomal miR-183 derived from the serum of patients with MI may be a novel diagnostic biomarker involved in the regulation of protein kinase activity. miR-183 may therefore be further developed for clinical use to benefit patients with coronary artery diseases.

Multilayer network analysis of miRNA and protein expression profiles in breast cancer patients

MiRNAs and proteins play important roles in different stages of breast tumor development and serve as biomarkers for the early diagnosis of breast cancer. A new algorithm that combines machine learning algorithms and multilayer complex network analysis is hereby proposed to explore the potential diagnostic values of miRNAs and proteins. XGBoost and random forest algorithms were employed to screen the most important miRNAs and proteins. Maximal information coefficient was applied to assess intralayer and interlayer connection. A multilayer complex network was constructed to identify miRNAs and proteins that could serve as biomarkers for breast cancer. Proteins and miRNAs that are nodes in the network were subsequently categorized into two network layers considering their distinct functions. The betweenness centrality was used as the first measurement of the importance of the nodes within each single layer. The degree of the nodes was chosen as the second measurement to map their signalling pathways. By combining these two measurements into one score and comparing the difference of the same candidate between normal tissue and cancer tissue, this novel multilayer network analysis could be applied to successfully identify molecules associated with breast cancer.

MicroRNA-494-3p Promotes Cell Growth, Migration, and Invasion of Nasopharyngeal Carcinoma by Targeting Sox7

Background:

There is mounting evidence that microRNAs play an important role in nasopharyngeal carcinoma, which is widely prevalent in South China and is the most prevalent metastatic cancer among head and neck cancers. Recently, it has been shown that miR-494 is involved in the progression and prognosis of nasopharyngeal carcinoma. However, little is known about the function and mechanism of miR-494-3p in nasopharyngeal carcinoma. In the present study, we aimed to investigate the effects of miR-494-3p on the migration and invasion of nasopharyngeal carcinoma and to further explore the underlying mechanisms of these processes.

Methods:

The expression levels of miR-494-3p and Sox7 in nasopharyngeal carcinoma specimens and nasopharyngeal carcinoma cell lines were measured using quantitative reverse transcription polymerase chain reaction. Luciferase reporter assay, quantitative reverse transcription polymerase chain reaction, and Western blotting were used to confirm whether Sox7 was a direct target of miR-494-3p. Additionally, the roles of miR-494-3p and Sox7 on cell proliferation, migration, and invasion of nasopharyngeal carcinoma were analyzed by Cell Counting Kit-8 (CCK-8) assay, wound healing assay, and Boyden chamber assay, respectively.

Results:

Our study demonstrated that miR-494-3p was commonly upregulated in nasopharyngeal carcinoma specimens and nasopharyngeal carcinoma cell lines compared with nontumor nasopharyngeal epithelial tissue or nasopharyngeal cells (NP69). Moreover, miR-494-3p negatively regulated Sox7 at the posttranscriptional level by binding to a specific site in the Sox7 3′-untranslated region. In addition, synthetic miR-494-3p mimics significantly promoted proliferation, migration, and invasion of S18 and S26 nasopharyngeal carcinoma cells, while a synthetic miR-494-3p inhibitor resulted in suppressed nasopharyngeal carcinoma cell migration and invasion.

Conclusion:

miR-494-3p promotes nasopharyngeal carcinoma cell growth, migration, and invasion by directly targeting Sox7. Our results suggest that miR-494-3p might be a potential therapeutic target for nasopharyngeal carcinoma.

MicroRNA-183 and microRNA-96 are associated with autoimmune responses by regulating T cell activation

MircoRNAs (miRs) are small molecules that regulate gene expression at the posttranscriptional level. They have been proposed to be involved in the regulation of several immune responses including autoimmunity. Here, we identified miR-183 and miR-96 to be highly expressed in CD4⁺ T cells from peripheral blood of Graves' orbitopathy (GO) patients as well as in human and murine T cells upon activation in vitro. By using Luciferase-based binding assays, we identified EGR-1 as target for miR-183 and miR-96. Overexpression of miR-183 and miR-96 in murine CD4⁺ T cells by retroviral gene transfer resulted in decreased EGR-1 and PTEN expression, elevated Akt phosphorylation and enhanced proliferation. In contrast, treatment of murine CD4⁺ T cells with specific antagomiRs increased EGR-1 and PTEN expression and interfered with the proliferative activity upon stimulation in vitro. Strikingly, adoptive transfer of miR-183 and miR-96 overexpressing antigen-specific T cells into INS-HA/Rag2KO mice accelerated the development of autoimmune diabetes, whereas transfer of antagomiR-treated cells delayed the disease onset. These results indicate that miR-183 and miR-96 have the ability to regulate the strength of T cell activation and thereby the development and severity of T cell-dependent autoimmune diseases.

The prognostic value of microRNA-183 in human cancers: A meta-analysis

BACKGROUND

Several studies have been conducted to explore the prognostic value of miR-183 in different types of cancer; however, their results were controversial. Therefore, the present meta-analysis was conducted to comprehensively evaluate the prognostic value of miR-183 expression level in cancer.

METHODS

A comprehensive literature search was carried out by searching PubMed and EMBASE database between January 1966 and April 2017. Fixed effect and random effect models were used to evaluate the pooled hazard risk (HR) and the relevant 95% confidence intervals (CIs). Subgroup analyses and sensitivity analysis were also carried out.

RESULTS

A total of 12 studies published between 2011 and 2017 were included in the present meta-analysis. The meta-analysis result indicated that there was a significant association between miR-183 expression level and overall survival (HR = 2.642; 95%CI: 2.152-3.245), and there was a significant association between miR-183 expression level and tumor progression (HR = 2.403; 95%CI: 1.267-4.559). In subgroup analysis, we found that high expression level was significantly associated with poor prognosis in most cancers (HR = 2.824, 95%CI: 2.092-3.813); however, low miR-183 level was significantly associated with poor prognosis in melanoma and pancreatic ductal adenocarcinoma (HR = 2.322, 95%CI: 1.337-4.031).

CONCLUSIONS

The results of our meta-analysis indicated that the highly expressed miR-183 might predict poor survival of patients with most cancer types, whereas the downregulated miR-183 level might be associated with poor prognosis in patients with melanoma and pancreatic ductal adenocarcinoma.

MicroRNAs in cancer metastasis and angiogenesis

Cancer metastasis is a malignant process by which tumor cells migrate from their primary site of origin to other organs. It is the main cause of poor prognosis in cancer patients. Angiogenesis is the process of generating new blood capillaries from pre-existing vasculature. It plays a vital role in primary tumor growth and distant metastasis. MicroRNAs are small non-coding RNAs involved in regulating normal physiological processes as well as cancer pathogenesis. They suppress gene expression by specifically binding to the 3′-untranslated region (3′-UTR) of their target genes. They can thus act as oncogenes or tumor suppressors depending on the function of their target genes. MicroRNAs have shown great promise for use in anti-metastatic cancer therapy. In this article, we review the roles of various miRNAs in cancer angiogenesis and metastasis and highlight their potential for use in future therapies against metastatic cancer.

MicroRNA-320 inhibits cell proliferation and invasion in breast cancer cells by targeting SOX4

Dysregulation of microRNAs (miRs) can contribute to cancer development and progression. In the present study, the function and underlying molecular mechanisms of miR-320 in breast cancer tumorigenesis and progression were investigated. The results of a reverse transcription-quantitative polymerase chain reaction analysis demonstrated that miR-320 was frequently downregulated in breast cancer tissues compared with adjacent normal tissues. In addition, knockdown of miR-320 in breast cancer cell lines promoted cell proliferation and invasion in vitro, whereas miR-320 overexpression had the opposite effect. Furthermore, a Dual-Luciferase reporter assay indicated that SRY-box 4 (SOX4) is a direct target of miR-320, and the restoration of SOX4 in miR-320-overexpressing cells attenuated the tumor-suppressive effects of miR-320. Collectively, these results indicated that miR-320 acts as a tumor suppressor in breast cancer tumorigenesis and progression.