Differential Expression Profiles Of miRNAs Research Articles

Retinal and Circulating miRNAs in Age-Related Macular Degeneration: An In vivo Animal and Human Study.

Age related macular degeneration (AMD) is the leading cause of blindness among people aged 50 and over. Retinal deposition of amyloid-β (Aβ) aggregates in AMD patients has suggested a potential link between AMD and Alzheimer's disease (AD). We have evaluated the differential retinal expression profile of miRNAs in a rat model of AMD elicited by Aβ. A serum profile of miRNAs in AMD patients has been also assessed using single TaqMan assay. Analysis of retina from rats intravitreally injected with Aβ revealed that miR-27a, miR-146a, and miR-155 were up-regulated in comparison to control rats. Seven miRNA (miR-9, miR-23a, miR-27a, miR-34a, miR-126, miR-146a, and miR-155) have been found to be dysregulated in serum of AMD patients in comparison to control group. Analysis of pathways has revealed that dysregulated miRNAs, both in the AMD animal model and in AMD patients, can target genes regulating pathways linked to neurodegeneration and inflammation, reinforcing the hypothesis that AMD is a protein misfolding disease similar to AD. In fact, miR-9, miR-23a, miR-27a, miR-34a, miR-146a, miR-155 have been found to be dysregulated both in AMD and AD. In conclusion, we suggest that miR-9, miR-23a, miR-27a, miR-34a, miR-146a, miR-155 represent potential biomarkers and new pharmacological targets for AMD.

MicroRNA expression profiles identify disease-specific alterations in systemic lupus erythematosus and primary Sjögren's syndrome.

The discovery of microRNAs (miRNAs) and their critical role in genetic control opened new avenues in understanding of various biological processes including immune cell lineage commitment, differentiation, proliferation and apoptosis. However, a given miRNA may have hundreds of different mRNA targets and a target might be regulated by multiple miRNAs, thus the characterisation of dysregulated miRNA expression profiles could give a better insight into the development of immunological disturbances in autoimmune diseases. The aim of our study was to examine the changes in miRNA expression profiles in patients with systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS). Eight SLE patients, 8 pSS patients and 7 healthy subjects were enrolled in the investigation. MiRNAs were isolated from peripheral blood mononuclear cells, and expression patterns were determined with Illumina next-generation sequencing technology. Since the immunopathogenesis of pSS and SLE encompasses pronounced B cell hyperactivity along with specific autoantibody production, we paid a special attention on the association between miRNA expression levels and altered peripheral B cell distribution. In SLE patients 135, while in pSS patients 26 miRNAs showed altered expression. Interestingly, the 25 miRNAs including miR-146a, miR-16 and miR-21, which were over-expressed in pSS patients, were found to be elevated in SLE group, as well. On the contrary, we observed the down-regulation of miR-150-5p, which is a novel and unique finding in pSS. Levels of several miRNAs over-expressed in SLE, were not changed in pSS, such as miR-148a-3p, miR-152, miR-155, miR-223, miR-224, miR-326 and miR-342. Expression levels of miR-223-5p, miR-150-5p, miR-155-5p and miR-342-3p, which miRNAs are potentially linked to B cell functions, showed associations with the B cell proportions within peripheral blood mononuclear cells. The observed differences in miRNA expression profiles and the better understanding of immune regulatory mechanisms of miRNAs may help to elucidate the pathogenesis of SLE and pSS.

Diet, gonadal sex, and sex chromosome complement influence white adipose tissue miRNA expression

BackgroundMicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression by targeting specific mRNA species for degradation or interfering with translation. Specific miRNAs are key regulators of adipogenesis, and are expressed at different levels in adipose tissue from lean and obese mice. The degree of lipid accumulation and distribution of white adipose tissue differs between males and females, and it is unknown whether sex differences in adipose tissue-specific miRNA expression may contribute to this dimorphism. Typically, sex differences are attributed to hormones secreted from ovaries or testes. However, the sex chromosome complement (XX versus XY) is also a determinant of sex differences and may regulate miRNA expression in adipocytes.ResultsTo identify sex differences in adipose tissue miRNA expression and to understand the underlying mechanisms, we performed high-throughput miRNA sequencing in gonadal fat depots of the Four Core Genotypes mouse model. This model, which consists of XX female, XX male, XY female, and XY male mice, allowed us to assess independent effects of gonadal type (male vs. female) and sex chromosome complement (XX vs. XY) on miRNA expression profiles. We have also assessed the effects of a high fat diet on sex differences in adipose tissue miRNA profiles. We identified a male–female effect on the overall miRNA expression profile in mice fed a chow diet, with a bias toward higher expression in male compared to female gonadal adipose tissue. This sex bias disappeared after gonadectomy, suggesting that circulating levels of gonadal secretions modulate the miRNA expression profile. After 16 weeks of high fat diet, the miRNA expression distribution was shifted toward higher expression in XY vs. XX adipose tissue. Principal component analysis revealed that high fat diet has a substantial effect on miRNA profile variance, while gonadal secretions and sex chromosome complement each have milder effects.ConclusionsOur results demonstrate that the overall miRNA expression profile in adipose tissue is influenced by gonadal hormones and the sex chromosome complement, and that expression profiles change in response to gonadectomy and high fat diet. Differential miRNA expression profiles may contribute to sex differences in adipose tissue gene expression, adipose tissue development, and diet-induced obesity.

Comparison of the Functional microRNA Expression in Immune Cell Subsets of Neonates and Adults.

Diversity of biological molecules in newborn and adult immune cells contributes to differences in cell function and atopic properties. Micro RNAs (miRNAs) are reported to involve in the regulation of immune system. Therefore, determining the miRNA expression profile of leukocyte subpopulations is important for understanding immune system regulation. In order to explore the unique miRNA profiling that contribute to altered immune in neonates, we comprehensively analyzed the functional miRNA signatures of eight leukocyte subsets (polymorphonuclear cells, monocytes, CD4+ T cells, CD8+ T cells, natural killer cells, B cells, plasmacytoid dendritic cells, and myeloid dendritic cells) from both neonatal and adult umbilical cord and peripheral blood samples, respectively. We observed distinct miRNA profiles between adult and neonatal blood leukocyte subsets, including unique miRNA signatures for each cell lineage. Leukocyte miRNA signatures were altered after stimulation. Adult peripheral leukocytes had higher let-7b-5p expression levels compared to neonatal cord leukocytes across multiple subsets, irrespective of stimulation. Transfecting neonatal monocytes with a let-7b-5p mimic resulted in a reduction of LPS-induced interleukin (IL)-6 and TNF-α production, while transfection of a let-7b-5p inhibitor into adult monocytes enhanced IL-6 and TNF-α production. With this functional approach, we provide intact differential miRNA expression profiling of specific immune cell subsets between neonates and adults. These studies serve as a basis to further understand the altered immune response observed in neonates and advance the development of therapeutic strategies.

Genome-wide analysis of miRNAs in the ovaries of Jining Grey and Laiwu Black goats to explore the regulation of fecundity.

Goat fecundity is important for agriculture and varies depending on the genetic background of the goat. Two excellent domestic breeds in China, the Jining Grey and Laiwu Black goats, have different fecundity and prolificacies. To explore the potential miRNAs that regulate the expression of the genes involved in these prolific differences and to potentially discover new miRNAs, we performed a genome-wide analysis of the miRNAs in the ovaries from these two goats using RNA-Seq technology. Thirty miRNAs were differentially expressed between the Jining Grey and Laiwu Black goats. Gene Ontology and KEGG pathway analyses revealed that the target genes of the differentially expressed miRNAs were significantly enriched in several biological processes and pathways. A protein-protein interaction analysis indicated that the miRNAs and their target genes were related to the reproduction complex regulation network. The differential miRNA expression profiles found in the ovaries between the two distinctive breeds of goats studied here provide a unique resource for addressing fecundity differences in goats.

Differential expression of microRNAs in the brains of mice subjected to increasing grade of mild traumatic brain injury

Objective: To investigate the effect of heterogeneity in mTBI on miRNA expression in mouse brain and to identify molecular pathways targeted by the modulated miRNAs.Methods: A weight drop device was used to induce four increasing grades of mTBI. MiRNA expression was evaluated using TaqMan rodent miRNA arrays. Bioinformatics analysis was done using the DIANA miRPath tool and Ingenuity Pathway Analysis software. Histology of brain sections was evaluated using H&E staining.Results: No histologic lesions were observed in the brains of injured mice; however, significant modulation in miRNA expression profile was observed. Global miRNA profiling indicated a trend of decrease in the number of modulated miRNAs from 24 hours to day 7 post-injury, except for the most severe grade of mTBI. Canonical pathways like calcium signalling, synaptic pathways and axon guidance pathway were the major targets of the modulated miRNAs. Network correlation analyses indicated an interaction between the modulated miRNAs and putative protein biomarkers of TBI.Conclusions: The data demonstrated that varying intensities of mTBI induced a differential miRNA expression profile in the brain post-injury. Pathways such as calcium and synaptic signalling were major targets of modulated miRNAs and may play a role in the pathophysiology of mTBI.

MicroRNA profiling in human breast cancer cell lines exposed to the anti-neoplastic drug cediranib.

Cediranib, a pan-tyrosine kinase inhibitor is showing promising results for the treatment of several solid tumours. In breast cancer, its effects remain unclear, and there are no predictive biomarkers. Several studies have examined the expression profiles of microRNAs(miRNAs) in response to different chemotherapy treatments and found that the expression patterns may be associated with the treatment response. Therefore, our aim was to evaluate the cellular behaviour and differential expression profiles of miRNAs in breast cancer cell lines exposed to cediranib. The biological effect of this drug was measured by viability, migration, invasion and cell death in invitro assays. Signaling pathways were assessed using a human phospho-receptor tyrosine kinase array. Furthermore, using a miRNA array and quantitative real-time PCR(qRT‑PCR), we assessed the relative expression of miRNAs following cediranib treatment. The breast cancer cell lines exhibited a distinct cytotoxic response to cediranib treatment. Cediranib exposure resulted in a decrease in the cell migration and invasion of all the breast cancer cell lines. Treatment with cediranib appeared to be able to modulate the activation of several RTKs that are targets of cediranib such as EGFR and a new potential target ROR2. Furthermore, this drug was able to modulate the expression profile of different microRNAs such as miR-494, miR-923, miR-449a, miR-449b and miR-886-3 in breast cancer cell lines. These miRNAs are reported to regulate genes involved in important molecular processes, according to bioinformatics prediction tools.

MicroRNA-126 and micro-/macrovascular complications of type 1 diabetes in the EURODIAB Prospective Complications Study.

Increasing evidence suggests a potential role of circulating miRNAs as clinical biomarkers, and loss of miRNA-126 has been proposed as a predictor of type 2 diabetes onset. However, a systematic analysis of circulating miRNAs in type 1 diabetic patients with micro-/macrovascular complications has not yet been performed. A cross-sectional nested case-control study from the EURODIAB Prospective Complications Study of 455 type 1 diabetic patients was performed. Case subjects (n=312) were defined as those with one or more complications of diabetes; control subjects (n=143) were those with no evidence of any complication. A differential miRNA expression profiling was performed in pooled serum samples from cases and controls. Furthermore, miR-126 levels were quantified by qPCR in all individual samples and associations with diabetic complications investigated. Twenty-five miRNAs differed in pooled samples from cases and controls. miR-126 levels were significantly lower in case than in control subjects, even after adjustment for age and sex. In logistic regression analyses, miR-126 was negatively associated with all complications (OR=0.85, 95% CI 0.75-0.96) as well as with each micro-/macrovascular complication examined separately. This was likely dependent of diabetes as associations were no longer significant after adjustment for both hyperglycemia and diabetes duration. However, a significant 25% risk reduction, independent of age, sex, A1C, and diabetes duration, was still observed for proliferative retinopathy (OR=0.75, 95% CI 0.59-0.95). In this large cohort of type 1 diabetic subjects, we found that miR-126 levels are associated with vascular complications of diabetes, particularly with proliferative retinopathy.

Identifying significant microRNA-mRNA pairs associated with breast cancer subtypes.

MicroRNAs (miRNAs) are small non-coding RNAs that help in post-transcriptional gene silencing. These endogenous RNAs develop a post-transcriptional gene-regulatory network by binding to complementary sequences of target mRNAs and essentially degrade them. Cancer is a class of diseases that is caused by the uncontrolled cell growth, thereby resulting into a gradual degradation of cell structure. Earlier researches have shown that miRNAs have significant biological involvement in cancer. Prolonged research in this genre has led to the identification of the functions of numerous miRNAs in cancer development. Studying the differential expression profiles of miRNAs and mRNAs together could help us in recognizing the significant miRNA-mRNA pairs from cancer samples. In this paper, we have analyzed the simultaneous over-expression of miRNAs and under-expression of mRNAs and vice versa to establish their association with cancer. This study focuses on breast tumor samples and the miRNA-mRNA target pairs that have a visible signature in such breast tumor samples. We have been able to identify the differentially expressed miRNAs and mRNAs, and further established relations between them to extract the miRNA-mRNA pairs that might be significant in the breast cancer types. This gives us the clue about the potential biomarkers for the breast cancer subtypes that can further help in understanding the progression of each of the subtypes separately. This might be helpful for the joint miRNA-mRNA biomarker identification.

Analysis of the MicroRNA expression profiles in the kidney of calcium oxalate stones rats

Objective To compare the miRNA expression profiles in kidney tissues of normal and calcium oxalate stone rats, and to explore the roles of different miRNAs in the regulation of kidney stone formation. Methods Sixteen 6-8 weeks old SD rats were divided into two groups, including the normal group and the model group randomly, between Sep 2015 and Dec 2015. The normal group was permitted to drink water freely; whereas the model of calcium oxalate stone group was established by freely drinking water with 1% ethylene glycol and 1% ammonium chloride. 28 days after molding, miRNA microarray and mRNA microarray were applied to evaluate the miRNA expressions in the kidney tissues of both normal and calcium oxalate stone rats. Target prediction, Gene Ontology (GO) analysis , Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were applied to predict the potential roles of miRNAs in the biological processes of stone formation. Results There were many crystals in calcium oxalate stone rat's kidney tissue sections whereas no crystal was detected in normal group. 38 miRNAs were differentially expressed with a more than 2-fold changing (P<0.05) between normal and calcium oxalate stone rats. Among those miRNAs, 18 miRNAs were up-regulated, while 20 miRNAs were down-regulated. 2 728 mRNAs were differentially expressed with a more than 2-fold change (P<0.05) between the two groups. Among them, 1 350 mRNAs were up-regulated and 1 378 were down-regulated. Gene Ontology analysis suggested that those differentially expressed miRNAs targeted many genes which were related to the function of calcium ion transport, injury, inflammatory response, oxidative stress and cell adhesion. KEGG pathway analysis suggested that those miRNAs were involved in inflammation-related pathway including cytokine-cytokine receptor interaction and chemokine signaling pathway. Conclusions There were significantly differences in miRNA expression profiles between normal and calcium oxalate stone rats, and these differentially expressed miRNAs might be associated with the function of regulation of calcium ion transport, inflammatory response, response to wounding and cell adhesion in the biological processes of calcium oxalate stone formation. Key words: Calcium oxalate stones; Microarray; MicroRNA expression profiles

Circulating human cytomegalovirus-encoded HCMV-miR-US4-1 as an indicator for predicting the efficacy of IFNα treatment in chronic hepatitis B patients.

The efficacy of interferon α (IFNα) therapy for chronic hepatitis B (CHB) patients is about 40% and often associates with adverse side-effects, thus identification of an easy accessible biomarker that can predict the outcome of IFNα treatment for individual CHB patients would be greatly helpful. Recent reports by us and others show that microRNAs encoded by human cytomegalovirus (HCMV) were readily detected in human serum and can interfere with lymphocyte responses required by IFNα therapeutic effect. We thus postulate that differential expression profile of serum HCMV miRNAs in CHB patients may serve as indicator to predict the efficacy of IFNα treatment for CHB patients. Blood was drawn from 56 individual CHB patients prior to IFNα treatment. By quantifying 13 HCMV miRNAs in serum samples, we found that the levels of HCMV-miR-US4-1 and HCMV-miR-UL-148D were significantly higher in IFNα-responsive group than in IFNα-non-responsive group. In a prospective study of 96 new CHB patients, serum level of HCMV-miR-US4-1 alone classified those who were and were not responsive to IFN-α treatment with correct rate of 84.00% and 71.74%, respectively. In conclusion, our results demonstrate that serum HCMV-miR-US4-1 can serve as a novel biomarker for predicting the outcome of IFNα treatment in CHB patients.

MicroRNA-27b up-regulated by human papillomavirus 16 E7 promotes proliferation and suppresses apoptosis by targeting polo-like kinase2 in cervical cancer.

The infection with high-risk human papillomavirus is linked to cervical cancer, nevertheless, the role of miRNAs regulated by HPV oncogenes in cancer progression remain largely unknown. Here, we knocked down endogenous E6/E7 in HPV16-positive CaSki cell lines, screened differences in miRNA expression profile with control using miRNA array. 38 miRNAs were down-regulated and 6 miRNAs were up-regulated in the E6/E7 silenced CaSki cells (>2-fold changes with P <0.05). The levels of miR-27b, miR-20a, miR-24, miR-93, and miR-106b were verified by qPCR in E6/E7 silenced CaSki and SiHa cells. MiR-27b, up-regulated by E7, promoted CaSki and SiHa cell proliferation and invasion, inhibit paclitaxel-induced apoptosis. Dual-luciferase experiment confirmed miR-27b down-regulated its target gene PLK2 through the “seed regions”. The tumor suppressor PLK2 inhibited SiHa cell proliferation, reduced cell viability, and promoted paclitaxel/cisplatin -induced apoptosis. Furthermore, DGCR8 was found to mediate the up-regulation of miR-27b by HPV16 E7. Our study demonstrated that HPV16 E7 could increase DGCR8 to promote the generation of miR-27b, which accelerated cell proliferation and inhibited paclitaxel-induced cell apoptosis through down-regulating PLK2. These findings provide an insight into the interaction network of viral oncogene, miR-27b and PLK2, and support the potential strategies using antisense nucleic acid of miR-27b for therapy of cervical cancer in the future.

Identification of differentially expressed miRNAs in individual breast cancer patient and application in personalized medicine.

MicroRNAs (miRNAs) have key roles in breast cancer progression, and their expression levels are heterogeneous across individual breast cancer patients. Traditional methods aim to identify differentially expressed miRNAs in populations rather than in individuals and are affected by the expression intensities of miRNAs in different experimental batches or platforms. Thus it is urgent to conduct miRNA differential expression analysis at an individual level for further personalized medicine research. We proposed a straightforward method to determine the differential expression of each miRNA in an individual patient by utilizing the reversal expression order of miRNA pairs between two conditions (cancer and normal tissue). We applied our method to breast cancer miRNA expression profiles from The Cancer Genome Atlas and two other independent data sets. In total, 292 miRNAs were differentially expressed in individual breast cancer patients. Using the differential expression profile of miRNAs in individual patients, we found that the deregulations of miRNA tend to occur in specific breast cancer subtypes. We investigated the coordination effect between the miRNA and its target, based on the hypothesis that one gene function can be changed by copy number alterations of the corresponding gene or deregulation of the miRNA. We revealed that patients exhibiting an upregulation of hsa-miR-92b and patients with deletions of PTEN did not tend to overlap, and hsa-miR-92b and PTEN coordinately regulated the pathway of ‘cell cycle' and so on. Moreover, we discovered a new prognostic signature, hsa-miR-29c, whose downregulation was associated with poor survival of breast cancer patients.

Early and late effects of prenatal corticosteroid treatment on the microRNA profiles of lung tissue in rats.

Glucocorticoids have been administered to mothers at risk of premature delivery to induce maturation of preterm fetal lungs and prevent the development of respiratory distress syndrome. Micro (mi)RNAs serve various crucial functions in cell proliferation, differentiation and organ development; however, few studies have demonstrated an association between miRNAs and lung development. The aim of the present study was to investigate alterations in the miRNA profiles of rat lung tissue following prenatal glucocorticoid therapy for fetal lung development. The differences in miRNA expression profiles were compared between postnatal days 7 (D7) and 120 (D120) rat lung tissues, followed by validation using reverse transcription-quantitative polymerase chain reaction. The miRNA profiles of rat lung tissues following prenatal dexamethasone (DEX) therapy were also investigated. miRNAs with 2-fold changes were selected for further analysis. At D120, 6 upregulated and 6 downregulated miRNAs were detected, compared with D7. Among these differentially expressed miRNAs, miR-101-3p and miR-99b-5p were associated with the lowest and highest expressions of miRNA at D7, respectively. A limited impact on the miRNA profiles of rat lung tissues was observed following prenatal DEX treatment, which may help to further clarify the mechanisms underlying normal lung development. However, the results of the present study cannot entirely elucidate the effects of prenatal DEX treatment on the lung development of premature infants, and further studies investigating the impact of prenatal corticosteroids on fetal lung miRNA profiles are required.

Abstract LB-C02: A KRAS dependency microRNA signature reveals a p62/Sqstm1-centered autophagy network regulated by mir-124

Abstract Background Non-small cell lung cancer (NSCLC) is derived from broncho-alveolar epithelial cells. NSCLCs frequently harbor mutations in the KRAS oncogene, yet only a subset of NSCLC cell lines depend on KRAS for sustained survival signaling. Cells that are more epithelial are highly KRAS dependent, whereas mesenchymal-like cells are KRAS independent for cell survival signaling. KRAS mutations are commonly associated with resistance to anti-cancer therapeutics. An important drug resistance mechanism is altered cellular plasticity, via a process known as epithelial-to-mesenchymal transition (EMT). Here, we aimed to identify and elucidate a KRAS dependent microRNA (miRNA) signaling network in epithelial cancer cells that modulates malignant growth and proliferation as well as cellular plasticity in NSCLC. Methods Differential miRNA expression in 6 KRAS mutant NSCLC cell lines (3 KRAS independent versus 3 KRAS dependent) was determined using Taqman low-density qPCR arrays (TLDA). To explore the functional relevance of differentially regulated miRNAs, gain-of-function studies by reconstitution experiments were performed using miRNA mimics in a panel of six KRAS independent cell lines. The molecular targets of mir-124-2 were computationally identified by TargetScan or miRWalk and experimentally verified using 3'UTR luciferase-based assays. Functional rescue of cell viability defects was determined by forced expression of GFP-p62/Sqstm1 in KRAS independent lung cancer cell lines. Results We identified a distinct differential miRNA expression profile in KRAS dependent versus KRAS independent NSCLC cells. This KRAS dependency miRNA signature included members of the mir-200 family, mir-34c and mir-205. Mir-200 and mir-205 reconstitution in KRAS independent cells modulated epithelial plasticity by down regulating Zeb1 protein expression and, thereby, increasing E-cadherin levels. Ectopic introduction of a subset of miRNAs in KRAS independent cells caused a consistent and pronounced loss of cell viability in all cell lines tested, including mir124, mir-625 and mir-518-3p. Ectopic expression of mir124 in KRAS independent cells caused cell viability defects by inducing apoptosis and autophagy. Using bioinformatics databases, we isolated p62/Sqstm1 and REL-A as key predicted targets of mir124-2. Mir-124-2 reconstitution in KRAS independent NSCLC cell lines caused decreased p62/Sqstm1 and REL-A protein expression levels. The effect of mir-124 on p62/Sqstm1 expression was verified using a p62-3'UTR-Luciferase construct. Overexpression of GFP-p62 in KRAS independent cells rescued the cell viability defects by mir124-2. Conclusion MiR-124 expression is down regulated in KRAS independent NSCLC cells. Reintroduction of mir124-2 induces cell viability defects in part, by targeting p62/Sqstm1 and REL-A. We conclude that, mir-124 down regulates p62/Sqstm1 expression to activate autophagic flux. This leads to down regulation of the NFκB pathway and subsequent reduction in expression of pro-survival genes such as IL-6 and IL-1β. Taken together, mir124-2 acts as a tumor suppressor in KRAS mutant NSCLC cells and provides a mechanistic link between activation of autophagy and control of proinflammatory signaling in NSCLC cell survival. Overexpression of mir124-2 might be of potential therapeutic value for the treatment of KRAS mutant NSCLC. Citation Format: ANITA K. MEHTA, Kevin Hua, William Whipple, Minh-Thuy Nguyen, Stephanie Bartley, Margaret McGuiness, Jeff Settleman, Joanne Weidhaas, Anurag Singh. A KRAS dependency microRNA signature reveals a p62/Sqstm1-centered autophagy network regulated by mir-124. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr LB-C02.

MiR-302a/b/c/d cooperatively inhibit BCRP expression to increase drug sensitivity in breast cancer cells

ObjectiveBCRP is overexpressed in many tumors and mediates multidrug resistance in breast cancer. In this study, we determined the involvement of miR-302S in the development of drug resistance in breast cancer. MethodsThe differential miRNA expression profiling in parental MCF-7 cells and its derivative mitoxantrone (MX)-resistant MCF-7 (MCF-7/MX) cells was determined by the microarray analysis. The levels of miR-302S family and BCRP mRNA expression were determined by using Quantitative Real-Time PCR. The targeting effect between the individuals of miR-302S and BCRP mRNA-3'UTR were detected by dual-luciferase reporter assay. Proteins of BCRP are represented by Western blot assay. Cell viability was assessed by MTS assay. Efflux capacity was evaluated using flow cytometry. ResultsThe miR-302S family including miR-302a, miR-302b, miR-302c, and miR-302d was significantly down-regulated in BCRP-overexpressing MCF-7/MX cells. Luciferase activity assay showed that miR-302 inhibited BCRP expression by targeting the 3′-untranslated region (UTR) of the BCRP mRNA. Overexpression of miR-302 increased intracellular accumulation of MX and sensitized breast cancer cells to MX. Furthermore, intratumoral injection of miR-302 potentiated the inhibitory effect of MX on tumor growth in mice transplanted with MCF-7/MX cells. Most importantly, miR-302S produced stronger effects than each individual member alone. ConclusionsThese findings suggest that miR-302 inhibits BCRP expression via targeting the 3′-UTR of BCRP mRNA. miR-302 members may cooperatively downregulate BCRP expression to increase chemosensitivity of breast cancer cells. miR-302 gene cluster may be a potential target for reversing BCRP-mediated chemoresistance in breast cancer.

MiR-34a screened by miRNA profiling negatively regulates Wnt/β-catenin signaling pathway in Aflatoxin B1 induced hepatotoxicity.

Aflatoxin-B1 (AFB1), a hepatocarcinogenic mycotoxin, was demonstrated to induce the high rate of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) participate in the regulation of several biological processes in HCC. However, the function of miRNAs in AFB1-induced HCC has received a little attention. Here, we applied Illumina deep sequencing technology for high-throughout profiling of microRNAs in HepG2 cells lines after treatment with AFB1. Analysis of the differential expression profile of miRNAs in two libraries, we identified 9 known miRNAs and 1 novel miRNA which exhibited abnormal expression. KEGG analysis indicated that predicted target genes of differentially expressed miRNAs are involved in cancer-related pathways. Down-regulated of Drosha, DGCR8 and Dicer 1 indicated an impairment of miRNA biogenesis in response to AFB1. miR-34a was up-regulated significantly, down-regulating the expression of Wnt/β-catenin signaling pathway by target gene β-catenin. Anti-miR-34a can significantly relieved the down-regulated β-catenin and its downstream genes, c-myc and Cyclin D1, and the S-phase arrest in cell cycle induced by AFB1 can also be relieved. These results suggested that AFB1 might down-regulate Wnt/β-catenin signaling pathway in HepG2 cells by up-regulating miR-34a, which may involve in the mechanism of liver tumorigenesis.

Differences in miRNA expression profiles between GIST and leiomyoma in human samples acquired by submucosal tunneling biopsy.

Background and study aims: Small gastrointestinal stromal tumors (GISTs) rarely have malignant potential with poor prognosis. Using conventional imaging to differentiate between small GISTs and leiomyoma, which often have similar characteristics, is difficult but essential in daily practice. Although some studies have reported on the utility of serum c-kit as a biomarker for non-small GIST and specific miRNA, clinical aspects of such testing are controversial. The aim of this study was to identify differences between small GIST and leiomyoma through the investigation of miRNA expression patterns in human cases. Patients and methods: MiRNA expression was examined in nine GIST (less than low risk, mean 18 mm in size) samples and seven leiomyoma samples acquired by a novel sampling method, submucosal tunneling biopsy (STB), which produces tumor specimens of submucosal tumor (SMT) without contamination of sufficient size to be examined under direct vision. Total RNA was extracted from these tissues and analyzed for miRNA expression patterns by microarray. Subsequently, real-time quantitative polymerase chain reaction (qPCR) were used to confirm specific miRNA overexpression, comparing GISTs with leiomyomas. Results: Microarray analysis revealed upregulation of the miR-140 family up to 20 times higher in GISTs than in leiomyomas. Real-time qPCR revealed that the expression level of miR-140-5 p in GISTs was 27.86 times higher than in leiomyomas; miR-140-3 p was 12.24 times higher as well. Conclusions: The STB method provided suitable SMT samples for miRNA analysis. MiR-140 family members may serve as specific biomarkers to distinguish GIST from leiomyoma.

Integrated analysis of the differential cellular and EBV miRNA expression profiles in microdissected nasopharyngeal carcinoma and non-cancerous nasopharyngeal tissues.

Nasopharyngeal carcinoma (NPC) is commonly diagnosed in southern Asia. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression post-transcriptionally. Increasing evidence suggests that the dysregulation of miRNAs promotes NPC tumorigenesis. Epstein-Barr virus (EBV) infection and EBV-encoded miRNAs are also associated with the development of NPC. However, it is unclear how cellular and EBV miRNAs jointly regulate target genes and signaling pathways in NPC. In the present study, we analyzed the differential cellular and EBV miRNA expression profiles in 20pooled NPC tissues using microarrays. We found that 19cellular miRNAs and 9 EBV miRNAs were upregulated and 31cellular miRNAs were downregulated in NPC tissues. Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the 19upregulated miRNAs target mainly the p53 signaling pathway in cancer, whereas the downregulated miRNAs regulate pathways related to cancer, focal adhesion and Erb, and MAPK signaling. In contrast, the upregulated EBV miRNAs target primarily the TGF-β and Wnt signaling pathways. Data also suggested that cellular miR-34b, miR-34c, miR-18a, miR‑200a/b, miR-449a, miR-31 and let-7 may be dysregulated in NPCs, and that the aberrant activation of their target genes in the p53 pathway and cell cycle enhance NPC cell survival and proliferation. In addition, EBV-miRNAs such as BART3 and BART5 target genes in the p53, TGF-β and Wnt signaling pathways to modulate NPC apoptosis and transformation. To better elucidate the interaction between miRNAs and target genes, we constructed an anti-correlated cellular and EBV miRNA/target gene regulatory network. The current findings may help dissect the roles played by cellular and EBV miRNAs during NPC tumorigenesis, and also provide useful biomarkers for the diagnosis and treatment of NPCs.

The roles of microRNAs in the regulation of tumor metastasis.

MicroRNAs (miRNAs) are small noncoding regulatory RNAs that regulate gene expression post-transcriptionally by either inhibiting protein translation or degrading target mRNAs. The differential expression profiles of miRNAs in different types of cancers and in the multi-step process of tumor progression indicate that miRNAs are involved in tumor onset, growth and progression. Metastasis is the most common cause of cancer-related mortality. Current evidence demonstrates that aberrant miRNA expression promotes or inhibits tumor metastasis by modulating the expression of numerous target genes. Therefore, the identification of metastasis-related miRNAs and a better understanding of the complex functions of miRNAs in tumor metastasis will provide potential diagnostic and prognostic biomarkers, as well as therapeutic targets for clinical application. Here, we review the functions of miRNAs in the control of multiple steps of tumor metastasis.