Altered miRNA Expression Profiles Research Articles

Análisis de la expresión de 4 micro-ARN en espermatozoides y su implicación en la fertilidad masculina

IntroductionMicroRNAs (miRNAs) are 22–24nt molecules involved in the gene expression regulation of many biological processes. Several authors have recently identified altered miRNA expression profiles in cases of male idiopathic infertility, suggesting its fundamental role in fertility regulation. ObjectiveTo characterize the expression of four miRNAs in sperm ribonucleic acid from fertile and infertile men. Material and methodsFour ejaculated samples from fertile donors and four samples from idiopathic infertile patients were obtained. Total RNA was isolated using the TRIzol method followed by a DNase treatment. To confirm proper ribonucleic acid purification, a polymerase chain reaction for the Protamine-1 gene (PRM-1) was performed. Afterwards, real-time polymerase chain reaction with specific primers for the miRNAs hsa-miR-23a, hsa-miR-744, hsa-let-7f and hsa-miR-1, together with the normalization control Mamm-U6, were performed. Differences in expression were quantified by the Fold-Change statistic and 95% confidence intervals. ResultsFor each individual, an average of 2.6×10−5ng ribonucleic acid/spermatozoa was obtained, with a purity of 1.72 (±0.05) and no traces of deoxyribonucleic acid. TaqMan analysis confirmed the presence of hsa-miR-23a, hsa-miR-744 y hsa-let-7f in all the samples. The expression of hsa-let-7f was significantly lower in three of the four samples from men with idiopathic infertility. ConclusionHuman spermatozoa contain the miRNAs hsa-miR-23a, hsa-miR-744 and hsa-let-7f. Hsa-let-7f expression was significantly reduced in three out of four infertile patients, suggesting the involvement of alterations in miRNA expression as the underlying cause of some cases of male infertility.

Correlation between hepatitis B virus protein and microRNA processor Drosha in cells expressing HBV

Drosha regulates the biogenesis of microRNAs (miRNAs) and plays an essential role in the regulation of gene expression. Infection with hepatitis B virus (HBV) causes chronic hepatitis and liver cirrhosis. It is also a major risk factor for hepatocellular carcinoma. Emerging evidence suggests that HBV alters miRNA expression profiles, but the mechanisms underlying this process have not yet been fully elucidated. We therefore examined how HBV affected the production of miRNAs. We found that Drosha mRNA and protein expression were downregulated in cells expressing the HBV genome. This was associated with a reduction in the activity of the Drosha gene promoter. Gene silencing of HBx by RNA interference significantly restored the expression of Drosha. In conclusion, our data show that HBV could downregulate Drosha expression by inhibiting promoter activity, and the transcription factors SP1 and AP-2α may be involved in this process. This provides a new understanding of the mechanism of HBV-induced miRNAs dysregulation.

Characterization of microRNA expression profiles associated with hepatitis B virus replication and clearance in vivo and in vitro

Alpha interferon (IFN-α) is an approved treatment for chronic hepatitis B (CHB). MicroRNA (miRNA) are currently known as a part of IFN-mediated antiviral defense. We aimed at characterizing the miRNA expression associated with hepatitis B virus (HBV) replication and IFN-mediated HBV clearance. We investigated the expression patterns of cellular miRNA induced by HBV replication and/or IFN-α treatment in HepG2 cells, and also analyzed the miRNA response in peripheral blood mononuclear cells in CHB patients on IFN-α treatment. The differentially expressed miRNA were verified using quantitative real-time polymerase chain reaction and an miRNA expression pattern was classified based on the final virological response. A total of 223 miRNA were differentially expressed (> 1.5 folds) between the HepG2.2.15 and HepG2 cells, including 24 highly differentially expressed miRNA (> 5 folds). With 12 h of IFN-α treatment, 23 totally differentially expressed miRNA were identified in HepG2 cells; whereas only five miRNA were identified in HepG2.2.15 cells. Similar amounts of the miRNA were regulated in patients with HBeAg or non-HBeAg seroconversion; whereas levels of eight miRNA were significantly differentially expressed between the two groups. HBV replication alters miRNA expression profiles and impairs IFN-inducible miRNA response in HepG2 cells. The miRNA expression pattern of peripheral blood mononuclear cells in CHB patients with IFN therapy can be associated with their therapeutic outcome.

Altered microRNA expression profile with miR‐27b down‐regulation correlated with disease activity of oral lichen planus

Increasing evidence indicates that microRNAs (miRNAs) play a vital role in the pathogenesis of inflammatory and autoimmune diseases. The objective of this study was to investigate the altered miRNA expression profile in patients with oral lichen planus (OLP) and determine the miR-27b expression. We compared miRNA expression patterns in oral biopsy specimens from patients with OLP (n=3) with those from normal controls (n=3) using microarray technology. We further assessed the miR-27b expression in specimens from patients with OLP (n=53) against controls (n=34) using real-time quantitative PCR (RT-QPCR), and miR-27b expression in specimens from patients with OLP (n=15) against controls (n=12) using in situ hybridization (ISH). Using microarray analysis, a total of 46 differentially expressed miRNAs with more than 2-fold change were identified, including 8 up-regulated and 38 down-regulated miRNAs. Both RT-QPCR and ISH analyses revealed that miR-27b was significantly down-regulated in OLP tissue, and miR-27b expression was even more suppressed in atrophic-erosive OLP than in reticular OLP. In addition, miR-27b was found to be expressed in the epithelial keratinocyte layer of both normal and OLP tissues. These data indicate that miRNAs may be the novel candidate biomarkers for the implication of miRNAs in the pathogenesis of OLP.

Alteration of mi-RNA expression profile after interferon treatment in HCV-infected Huh7.5.1 cells

To screen the mi-RNA expression profile after interferon treatment in cells infected with hepatitis C virus (HCV). Huh-7.5.1 cells was infected with HCV by in vitro transcription and cultured with interferon. The mi-RNA microarray was used to measure the mi-RNA expression in the control group, HCV transcription group and interference group. Intra-group differences were analyzed by the 2 ((-delt delt CT)) method. With mi-RNA expressed in normal Huh-7.5.1 cells as a benchmark, expressions of 13 kinds of mi-RNAs were up-regulated after HCV infection and then down-regulated following interferon treatment; 7 were down-regulated after HCV infection and then up-regulated following interferon treatment. mi-RNA10a, mi-RNA21, mi-RNA149, mi-RNA152 and mi-RNA210 may be related to hepatitis C virus replication and transcription.

MiR-192 inhibits nucleotide excision repair by targeting ERCC3 and ERCC4 in HepG2.2.15 cells

Deficient DNA repair capacity is associated with genetic lesions accumulation and susceptibility to carcinogenesis. MicroRNAs (miRNAs) are small non-coding RNAs that regulate various cellular pathways including DNA repair. Here we hypothesized that the existence of HBV products may interfere with cellular nucleotide excision repair (NER) through microRNA-mediated gene regulation. We found that NER was impaired in HepG2.2.15 cells, a stable HBV-expressing cell line, compared with its parental cell line HepG2. Altered miRNA expression profile, in particular the significant upregulation of miR-192, was observed in HepG2.2.15 cells. Additionally, ERCC3 and ERCC4, two key factors implicated in NER, were identified as targets of miR-192 and over-expressing miR-192 significantly inhibited cellular NER. These results indicated that persistent HBV infection might trigger NER impairment in part through upregulation of miR-192, which suppressed the levels of ERCC3 and ERCC4. It provides new insight into the effect of chronic HBV infection on NER and genetic instability in cancer.

Altered levels of the onco-microRNA 21 and the tumor-supressor microRNAs 143 and 145 in advanced rectal cancer indicate successful neoadjuvant chemoradiotherapy

microRNAs (miRNAs) are small non-coding RNAs with important post-transcriptional regulatory functions. miRNA-21 (miR-21) is upregulated and miR-143 and miR-145 are downregulated in colorectal carcinoma. The aim of our study was to determine if these miRNAs change their expression levels in response to neoadjuvant chemoradiotherapy in advanced rectal cancer. Forty patients with advanced rectal cancer (clinical uT3/T4 Nx) were included. All patients underwent neoadjuvant chemoradiotherapy and surgical resection. Expression of miR-21, -143 and -145 was examined in macrodissected tumor tissue before and after chemoradiotherapy and normal rectal tissue from the resection specimen. RNA was extracted from formalin-fixed and paraffin-embedded tissue by TRIzol method, polyadenylated, reverse transcribed and analyzed by real-time PCR. Therapy response was assessed according to pathological tumor regression. miR-21 was more highly expressed in tumor tissue than in non-tumorous tissue. However, there was a moderately lower expression in post-therapeutic tumor tissue compared to pre-therapeutic tumor tissue. There was a significant upregulation of miR-143 and miR-145 in post-therapeutic tumor tissue compared to pre-therapeutic tumor tissue. According to the predictive and prognostic value of the analyzed miRNAs, a significant correlation between miR-145 expression and tumor regression was seen. Patients with a low intratumoral post-therapeutic expression had significantly more often a worse response to neoadjuvant therapy compared to patients with a high expression of miR145. The present results support the hypothesis that chemoradiotherapy can profoundly alter miRNA expression profiles. miRNAs might play important roles as molecular biomarkers in the prediction of response to treatment and prognosis.

MicroRNA expression alteration after arsenic trioxide treatment in HepG‐2 cells

More and more microRNA (miRNA) are found to be involved in tumor genesis and progress. Arsenic trioxide has been an effective chemotherapeutic drug in cancer therapy for many years. In this study, we aimed to find the miRNA involved in the mechanisms of arsenic trioxide treatment in cancer therapy. We detected the expression profile of miRNA by miRNA microarray and quantitative real-time polymerase chain reaction. Cell viability assay, flow cytometry analysis, prediction of miRNA targets, Western blot analysis and luciferase reporter assay were carried out to determine the role of one selected miRNA, namely mir-29a, in affecting the biological behaviors of HepG-2 cells. Among the 677 human miRNA in the microarray, five miRNA were upregulated and four were downregulated in HepG-2 cells treated with arsenic trioxide compared to their controls. If only changes above two folds were considered, four miRNA were identified, namely miR-24, miR-29a, miR-30a and miR-210, which were all upregulated. Among them, miR-29a showed a positive therapeutic effect in liver cancer cells by inhibiting cell growth and inducing cell apoptosis, and PPM1D was confirmed to be the target gene of miR-29a. Furthermore, a synergy effect was detected between miR-29a and arsenic trioxide. Arsenic trioxide altered miRNA expression profile in HepG-2 cells. Among the altered miRNA, miR-29a seemed to take a role in the mechanism of arsenic trioxide in liver cancer therapy. The synergy effect between miR-29a and arsenic trioxide may offer this drug a new chance in cancer therapy by decreasing its dose and toxic side-effects.

Epigenetic Changes Induced by Air Toxics: Formaldehyde Exposure Alters miRNA Expression Profiles in Human Lung Cells

BackgroundExposure to formaldehyde, a known air toxic, is associated with cancer and lung disease. Despite the adverse health effects of formaldehyde, the mechanisms underlying formaldehyde-induced disease remain largely unknown. Research has uncovered microRNAs (miRNAs) as key posttranscriptional regulators of gene expression that may influence cellular disease state. Although studies have compared different miRNA expression patterns between diseased and healthy tissue, this is the first study to examine perturbations in global miRNA levels resulting from formaldehyde exposure.ObjectivesWe investigated whether cellular miRNA expression profiles are modified by formaldehyde exposure to test the hypothesis that formaldehyde exposure disrupts miRNA expression levels within lung cells, representing a novel epigenetic mechanism through which formaldehyde may induce disease.MethodsHuman lung epithelial cells were grown at air–liquid interface and exposed to gaseous formaldehyde at 1 ppm for 4 hr. Small RNAs and protein were collected and analyzed for miRNA expression using microarray analysis and for interleukin (IL-8) protein levels by enzyme-linked immunosorbent assay (ELISA).ResultsGaseous formaldehyde exposure altered the miRNA expression profiles in human lung cells. Specifically, 89 miRNAs were significantly down-regulated in formaldehyde-exposed samples versus controls. Functional and molecular network analysis of the predicted miRNA transcript targets revealed that formaldehyde exposure potentially alters signaling pathways associated with cancer, inflammatory response, and endocrine system regulation. IL-8 release increased in cells exposed to formaldehyde, and results were confirmed by real-time polymerase chain reaction.ConclusionsFormaldehyde alters miRNA patterns that regulate gene expression, potentially leading to the initiation of a variety of diseases.

Pediatric Leukemia-Specific miRNA Expression Profiles Induced by the Leukemic Stem Cell Niche

AbstractAbstract 942 Background:Emerging evidence suggests that microRNAs (miRNAs) are critical in cancer and adult leukemia by functioning as tumor suppressors and/or oncogenes. Zhang et al identified 32 pediatric acute myeloid leukemia (AML)-specific miRNA patterns by analysis of bone marrow (BM) samples (1). They also established potential miRNAs as biomarkers for predicting CNS-relapse in pediatric acute lymphocytic leukemia (ALL). Altered miRNA expression disrupts normal hematopoiesis and might play a role in niche-induced oncogenesis. Dysfunction of mesenchymal stromal cells induces formation of myeloid sarcomas that infiltrate in the surrounding tissues (2). Previously, we described that mesenchymal stem cells (MSC) of the BM microenvironment participate in leukemic stem cell regulation in an in vivo model of the childhood AML stem cell niche(3). These human MSC niches, created in ectopic bioengineered 3D scaffolds, supported leukemogenesis in NOD/SCID mice. Pediatric AML engrafted at 1 month in the MSC-coated scaffolds in the mice and was retained in the niche up to 4 months, after which distant seeding to murine BM, liver and spleen occurred. The bioengineered niche created a sanctuary for quiescent leukemia cells and at 4 months the AML cells exited the niche and spread hematogenously, mimicking leukemia relapse. Analysis of miRNA patterns in our leukemia niche model could provide novel directions for individual risk-adapted therapy in childhood leukemia. Objective:To analyze miRNA expression patterns of pediatric AML after exposure to the niche microenvironment at different time points. Design and Method:miRNAs were obtained from primary CD34+ selected AML cells at (d0) Day0= no niche exposure, (1Mo) 1 month =niche engraftment, (4Mo) 4 months=hematogenous spread with leukemic exit from the niche. miRNAs were isolated from single cell suspensions with the mirVana miRNA isolation kit (Ambion) and analyzed on an Ilumina MicroRNA Expression Profiling single Beadchip (#RNA probes = 1145). Results:498/1145 miRNAs expression profiles were selected with a detection p value < 0.00001. Out of 498 miRNAs expressed in the leukemic niche model, 23 were previously described as AML-specific miRNAs (2). 10/23 miRNAs were significantly upregulated and 13/23 were downregulated. Pediatric AML-specific miRNAs – miR100 and miR125b had high expression profile at baseline, but were down regulated upon contact with the niche. AML miR195 and miR193a had low expression at baseline, but miR195 was upregulated on engraftment while miR193a only upregulated at the time of hematogenous spread (niche exit). CNS-relapse in ALL might represent a physiological mechanism of leukemic exit of dormant cells from the niche sanctuary. Consistent with this notion, the same expression profile that was found in CNS-relapse in ALL patients (miR198 up – miR551a downregulated) was seen in our model when AML cells became invasive and exited the niche at 4 months. [Display omitted] Conclusion:1) Altered miRNA expression profile of pediatric AML cells is observed after niche exposure (1Mo) compared to baseline AML cells without niche exposure (d0).2) Altered miRNA expression profile is found when pediatric AML cells spread via the bloodstream (4Mo). In this model, miRNA expression can be correlated to biological behavior of leukemia cells at different time points.3) Pediatric AML cells that escape from the leukemic stem cell niche and become invasive have the same miRNA expression pattern as published CNS-relapsed ALL cells.4) The leukemic stem cell niche model can help identify novel treatment targets for pediatric leukemia patients.(1)Zhang et al. 2009, PloSOne, 4, p1(2)Raaijmakers et al. 2010, Nature, 464, p852(3)Vaiselbuh et al, 2010, Tissue Eng Part C Methods, June 29 (ePub) Disclosures:No relevant conflicts of interest to declare.

Niemann–Pick type C fibroblasts have a distinct microRNA profile related to lipid metabolism and certain cellular components

MicroRNAs (miRNAs) are non-coding RNAs that regulate gene expression at post-transcriptional level. Dysregulation of miRNA expression may lead to severe pathophysiologies in human cells. Niemann–Pick type C (NPC) disease is a complex lipid storage disease characterized by late endosomal–lysosomal accumulation of multiple lipid molecules. Our aim was to characterize the miRNA profile in NPC fibroblasts as they may play an active role in the NPC disease associated changes in the cellular physiology. To investigate the miRNA expression, total RNAs were isolated from cultured human NPC fibroblasts and healthy fibroblasts and then, TaqMan Low-Density Array system containing 365 mature human miRNAs was used. Expression differences between the healthy and NPC cells were detected according to the relative quantification values. Target genes were predicted by using three different algorithms and classified regarding NPC related biological processes and cellular components. We found that three miRNAs, miR-196a, miR-196b and miR-296 were up-regulated (>3.5-fold increase, p < 0.05) whereas 38 miRNAs were significantly down-regulated in NPC cells (>3.5-fold decrease, p < 0.05). Among these non-coding RNAs, miR-98 was the most down-regulated (−33.3-fold) miRNA and miR-143, the lipid biosynthesis associated miRNA, had a 20-fold decreased expression in the NPC cells. Additionally, gene ontology analyses of the target genes suggested a distinct role for each miRNA. Our results show that NPC fibroblasts have an altered miRNA expression profile and certain miRNAs have importance in disease pathogenesis as well as the therapeutic capacity to correct lipid related pathophysiologies in the NPC cells.

MicroRNA-dependent regulation of PTEN after arsenic trioxide treatment in bladder cancer cell line T24

Arsenic trioxide has shown remarkable biological activity against bladder cancer in some clinical studies. However, the mechanism of its action is unknown. Our aim was to find the relationship between miRNAs and arsenic trioxide treatment by using T24 human bladder carcinoma cells. By performing microRNA microarray and quantitative real-time PCR after ATO treatment, we found that expression levels of several miRNAs, in particular, miRNA-19a, were significantly decreased in T24 cell line. Furthermore, cell proliferation assay, flow cytometry analysis, prediction of miRNA targets, Western blot analysis, and luciferase reporter assay were performed to determine the role of mir-19a in affecting the biological behaviors of T24 cells. Several miRNAs were up-regulated or down-regulated in T24 cells treated with arsenic trioxide compared to their controls. If only changes above two folds were considered, two miRNAs were identified, miRNA-19a was down-regulated, while miRNA-222* was up-regulated. Among them, knockdown of miRNA-19a by anti-miRNA-19a transfection showed a positive therapeutic effect in bladder cancer cells by inhibiting cell growth and inducing cell apoptosis targeting PTEN through the PTEN/Akt pathway. Besides this, a synergy effect was detected between knockdown of miRNA-19a and arsenic trioxide. Arsenic trioxide altered miRNA expression profile in T24 cells. It seems miRNA-19a plays a critical role in the mechanism of arsenic trioxide treatment in bladder cancer. The synergy effect between miRNA-19a and arsenic trioxide that advocates targeting the mir-19a may represent a potential approach to enhance the efficacy and safety of ATO to treat bladder cancer by a decrease in dose.

Genome-scale microRNA identify small RNA modulators of the effect of berberine on pancreatic cancer cell growth

MicroRNAs (miRNAs) are newly identified small RNA molecules up to 22 nucleotides in length. miRNAs have emerged as important regulators of genes involved in many biological processes, including development, cell proliferation and differentiation, apoptosis and metabolism. Disturbance of microRNA expression may play a role in the initiation and progression of certain diseases including cancer. Human cancers commonly exhibit an altered expression profile of miRNAs with oncogenic (miR-21) or tumor-suppressive (miR-34a) activity. Pancreatic cancer is one of the most aggressive human malignancies with an incidence rates almost identical to mortality rates. This discouraging information is due to the lack of improvement in detection and diagnosis strategies and the paucity of breakthroughs in treatment regimens. A successful drug development in this disease continues to be a major challenge. Recently, a microRNA expression signature has been identified that is associated with pancreatic cancer. Berberine is an isoquinoline alkaloid, isolated from Rhizoma coptidis, and reported to have anti-cancer effects in different human cancer cells. There is however, no available information on the effect of berberine on global miRNA expression pattern in pancreatic cancer. Here we carried out a global miRNA-based expression profiling study in order to identify novel molecular miRNA targets mediating the growth inhibitory effects of berberine on pancreatic cancer cells. Among the 59 significantly expressed genes, 14 were significantly up-regulated and 45 were significantly down-regulated in their expression. Our results showed, for the first time, that berberine was able to modulate the miRNA signature of pancreatic cancer cells.

Regulation of microRNAs by Natural Agents: An Emerging Field in Chemoprevention and Chemotherapy Research

In recent years, microRNAs have received greater attention in cancer research. These small, non-coding RNAs could inhibit target gene expression by binding to the 3' untranslated region of target mRNA, resulting in either mRNA degradation or inhibition of translation. miRNAs play important roles in many normal biological processes; however, studies have also shown that aberrant miRNA expression is correlated with the development and progression of cancers. The miRNAs could have oncogenic or tumor suppressor activities. Moreover, some miRNAs could regulate formation of cancer stem cells and epithelial-mesenchymal transition phenotype of cancer cells which are typically drug resistant. Furthermore, miRNAs could be used as biomarkers for diagnosis and prognosis, and thus miRNAs are becoming emerging targets for cancer therapy. Recent studies have shown that natural agents including curcumin, isoflavone, indole-3-carbinol, 3,3'-diindolylmethane, (-)-epigallocatechin-3-gallate, resveratrol, etc. could alter miRNA expression profiles, leading to the inhibition of cancer cell growth, induction of apoptosis, reversal of epithelial-mesenchymal transition, or enhancement of efficacy of conventional cancer therapeutics. These emerging results clearly suggest that specific targeting of miRNAs by natural agents could open newer avenues for complete eradication of tumors by killing the drug-resistant cells to improve survival outcome in patients diagnosed with malignancies.

Implication of microRNAs in drug resistance for designing novel cancer therapy

Recently, microRNAs (miRNAs) have received increasing attention in the field of cancer research. miRNAs play important roles in many normal biological processes; however, the aberrant miRNA expression and its correlation with the development and progression of cancers is an emerging field. Therefore, miRNAs could be used as biomarkers for diagnosis of cancer and prediction of prognosis. Importantly, some miRNAs could regulate the formation of cancer stem cells and the acquisition of epithelial-mesenchymal transition, which are critically associated with drug resistance. Moreover, some miRNAs could target genes related to drug sensitivity, resulting in the altered sensitivity of cancer cells to anti-cancer drugs. Emerging evidences have also shown that knock-down or re-expression of specific miRNAs by synthetic anti-sense oligonucleotides or pre-miRNAs could induce drug sensitivity, leading to increased inhibition of cancer cell growth, invasion, and metastasis. More importantly, recent studies have shown that natural agents including isoflavone, 3,3'-diindolylmethane, and (-)-epigallocatechin-3-gallate altered miRNA expression profiles, leading to an increased sensitivity of cancer cells to conventional therapeutics. These emerging results suggest that specific targeting of miRNAs by different approaches could open new avenues for cancer treatment through overcoming drug resistance and thereby improve the outcome of cancer therapy.

Epigenetic Changes Induced by Air Toxics: Formaldehyde Exposure Alters miRNA Expression Profiles in Human Lung Cells

Epigenetic Changes Induced by Air Toxics: Formaldehyde Exposure Alters miRNA Expression Profiles in Human Lung Cells

P53-Inducible Micrornas 192 and 215 Regulate p53 Expression and IGF1 Axis in Multiple Myeloma.

Abstract 1973Poster Board I-996Multiple myeloma (MM) is an incurable neoplastic disease of B cell origin, affecting 50,000 patients in the United States, occurring in approximately 16,000 new individuals each year. In MM, mutation or deletion of p53 is rarely detected at diagnosis, although both become more frequent in advanced disease. Therapeutic activation of p53 might therefore be particularly suitable for the treatment of MM. The discovery of microRNAs (miRNAs) has revealed a new level of regulation of protein expression. We have shown that an altered miRNA expression profile plays a role in the malignant transformation of plasma cells (PCs); we recently published the first comprehensive global microRNA expression profiles of MM, monoclonal gammopathy of undetermined significance (MGUS) and contrasted these expression patterns with that of normal plasma cells (PCs). Now we have used nutlin-3a, a recently developed small-molecule activator of p53, that efficiently disrupts the p53-MDM2 interaction, to profile a p53 miRNA activation pathway in the MM1s cell line. Results of the analysis have shown differential expression of 46 individual miRNAs after p53 activation, 14 showing up-regulation and 32 showing down-regulation. We confirmed our data by qRT-PCR in p53 wild type and mutated MM cell lines and in primary MM cells. Our results confirm published results; after p53 stabilization we found up-regulation of the miR-34a, but we also detected strong up-regulation of several other miRNAs. In fact we found that p53 induces two additional, mutually related clusters of miRNAs, leading to the up-regulation of miR-192, miR-194, and miR-215. The same miRNAs were detected at high levels in normal plasma cells (n.3) but were severely reduced in many untreated MM samples (n.22). Here we characterize the promoter and the p53 activation site for miR-192-194 cluster on chromosome 11(q13.1) but we have also confirmed the previous published p53 consensus site for miR-215-194 cluster on chromosome 1(q41) in multiple myeloma cells. Furthermore we found that miR-192 and its cousin miR-215 but not miR-194 can each contribute to enhanced CDKN1A/p21 levels, colony suppression, cell cycle arrest in multiple myeloma cells acting directly on p53 regulation. On the other hand, we define that IGF-1 and IGFR are direct targets of miR-192-215. In fact the re-expression of these miRNAs in multiple myeloma cells blocks their migration through both endothelial barriers and associated bone marrow stroma. Our data suggest that downstream signaling in the p53 pathway is functional in MM cells and able to induce miRNAs that play a pivotal role in cell cycle progression, mobility and invasive properties of these cells. These studies provide the basis for the development of new miRNA-targeted therapies for MM. Disclosures:No relevant conflicts of interest to declare.

MicroRNAs Differentially Expressed in ACTH-Secreting Pituitary Tumors

MicroRNAs (miRNAs) are small noncoding RNAs, functioning as antisense regulators of gene expression by targeting mRNA and contributing to cancer development and progression. More than 50% of miRNA genes are located in cancer-associated genomic regions or in fragile sites of the genome. The aim of the study was to analyze the differential expression of let-7a, miR-15a, miR-16, miR-21, miR-141, miR-143, miR-145, and miR-150 in corticotropinomas and normal pituitary tissue and verify whether their profile of expression correlates with tumor size or remission after treatment. ACTH-secreting pituitary tumor samples were obtained during transphenoidal surgery from patients with Cushing disease and normal pituitary tissues from autopsies. The relative expression of miRNAs was measured by real-time PCR using RNU44 and RNU49 as endogenous controls. Relative quantification of miRNA expression was calculated using the 2(-DeltaDeltaCt) method. We found underexpression of miR-145 (2.0-fold; P = 0.04), miR-21 (2.4-fold; P = 0.004), miR-141 (2.6-fold; P = 0.02), let-7a (3.3-fold; P = 0.003), miR-150 (3.8-fold; P = 0.04), miR-15a (4.5-fold; P = 0.03), miR-16 (5.0-fold; P = 0.004), and miR-143 (6.4-fold; P = 0.004) in ACTH-secreting pituitary tumors when compared to normal pituitary tissues. There were no differences between miRNA expression and tumor size as well as miRNA expression and ratio of remission after surgery, except in patients presenting lower miR-141 expression who showed a better chance of remission. Our results support the possibility that altered miRNA expression profile might be involved in corticotrophic tumorigenesis. However, the lack of knowledge about miRNA target genes postpones full understanding of the biological functions of down-regulated or up-regulated miRNAs in corticotropinomas.

Modulation of miRNA activity in human cancer: a new paradigm for cancer gene therapy?

MicroRNAs (miRNAs) were discovered more than a decade ago as noncoding, single-stranded small RNAs (approximately 22 nucleotides) that control the timed gene expression pattern in Caenorhabditis elegans life cycle. A number of these evolutionarily conserved, endogenous miRNAs have been shown to regulate mammalian cell growth, differentiation and apoptosis. miRNAs are multispecific by nature. The individual miRNA is capable of modulating the expression of a network of mRNAs that it binds by imperfect sequence complementarity. Human cancers commonly exhibit an altered expression profile of miRNAs with oncogenic (miR-21, miR-106a and miR-155) or tumor-suppressive (let-7, miR-15a/16, miR-34a and miR-143/145) activity. As consistent with the natural function of miRNAs in specifying cellular phenotype, miRNA-based cancer gene therapy offers the theoretical appeal of targeting multiple gene networks that are controlled by a single, aberrantly expressed miRNA. Reconstitution of tumor-suppressive miRNA, or sequence-specific knockdown of oncogenic miRNAs by 'antagomirs,' has produced favorable antitumor outcomes in experimental models. We discuss pending issues that need to be resolved prior to the consideration of miRNA-based experimental cancer gene therapy. These include the need for definitive mRNA target validation, our incomplete understanding of rate-limiting cellular components that impact the efficiency of this posttranscriptional gene-silencing phenomenon, the possibility for nonspecific immune activation and the lack of a defined, optimal mode of delivery.

Altered expression of MicroRNA in synovial fibroblasts and synovial tissue in rheumatoid arthritis

MicroRNAs (miRNA) have recently emerged as a new class of modulators of gene expression. In this study we investigated the expression, regulation, and function of miR-155 and miR-146a in rheumatoid arthritis (RA) synovial fibroblasts (RASFs) and RA synovial tissue. Locked nucleic acid microarray was used to screen for differentially expressed miRNA in RASFs treated with tumor necrosis factor alpha (TNFalpha). TaqMan-based real-time polymerase chain reaction was applied to measure the levels of miR-155 and miR-146a. Enforced overexpression of miR-155 was used to investigate the function of miR-155 in RASFs. Microarray analysis of miRNA expressed in RASFs treated with TNFalpha revealed a prominent up-regulation of miR-155. Constitutive expression of both miR-155 and miR-146a was higher in RASFs than in those from patients with osteoarthritis (OA), and expression of miR-155 could be further induced by TNFalpha, interleukin-1beta, lipopolysaccharide, poly(I-C), and bacterial lipoprotein. The expression of miR-155 in RA synovial tissue was higher than in OA synovial tissue. Enforced expression of miR-155 in RASFs was found to repress the levels of matrix metalloproteinase 3 (MMP-3) and reduce the induction of MMPs 3 and 1 by Toll-like receptor ligands and cytokines. Moreover, compared with monocytes from RA peripheral blood, RA synovial fluid monocytes displayed higher levels of miR-155. This study provides the first description of increased expression of miRNA miR-155 and miR-146a in RA. Based on these findings, we postulate that the inflammatory milieu may alter miRNA expression profiles in resident cells of the rheumatoid joints. Considering the repressive effect of miR-155 on the expression of MMPs 3 and 1 in RASFs, we hypothesize that miR-155 may be involved in modulation of the destructive properties of RASFs.