MicroRNAs in normal and malignant hematopoiesis

miRNA-221 and miRNA-483-3p Dysregulation in Esophageal Adenocarcinoma

Alterations in microRNA (miRNA) expression have been reported in different cancers. We assessed the expression of 754 oncology-related miRNAs in esophageal adenocarcinoma (EAC) samples and evaluated their correlations with clinical parameters. We found that miR-221 and 483-3p were consistently upregulated in EAC patients vs. controls (Wilcoxon signed-rank test: miR-221 p < 0.0001; miR-483-3p p < 0.0001). Kaplan-Meier analysis showed worse cancer-related survival among all EAC patients expressing high miR-221 or miR-483-3p levels (log-rank p = 0.0025 and p = 0.0235, respectively). Higher miR-221 or miR-483-3p levels also correlated with advanced tumor stages (Mann-Whitney p = 0.0195 and p = 0.0085, respectively), and overexpression of miR-221 was associated with worse survival in low-risk EAC patients. Moreover, a significantly worse outcome was associated with the combined overexpression of miR-221 and miR-483-3p (log-rank p = 0.0410). To identify target genes affected by miRNA overexpression, we transfected the corresponding mimic RNA (miRVANA) for either miR-221 or miR-483-3p in a well-characterized esophageal adenocarcinoma cell line (OE19) and performed RNA-seq analysis. In the miRNA-overexpressing cells, we discovered a convergent dysregulation of genes linked to apoptosis, ATP synthesis, angiogenesis, and cancer progression, including a long non-coding RNA associated with oncogenesis, i.e., MALAT1. In conclusion, dysregulated miRNA expression, especially overexpression of miR-221 and 483-3p, was found in EAC samples. These alterations were connected with a lower cancer-specific patient survival, suggesting that these miRNAs could be useful for patient stratification and prognosis.

From Euglycemia to Recent Onset of Type 2 Diabetes Mellitus: A Proof-of-Concept Study on Circulating microRNA Profiling Reveals Distinct, and Early microRNA Signatures

Background and aim-Alterations in circulating microRNA (miRNA) expression patterns are thought to be involved in the early stages of prediabetes, as well as in the progression to overt type 2 diabetes mellitus (T2D) and its vascular complications. However, most research findings are conflicting, in part due to differences in miRNA extraction and normalization methods, and in part due to differences in the study populations and their selection. This cross-sectional study seeks to find new potentially useful biomarkers to predict and/or diagnose T2D by investigating the differential expression patterns of circulating miRNAs in the serum of patients with impaired fasting glucose (IFG) and new-onset T2D, with respect to euglycemic controls, using a high-throughput 384-well array and real-time PCR. Methods-Thirty subjects, aged 45-65 years, classified into three matched groups (of 10 participants each) according to their glycometabolic status, namely (1) healthy euglycemic controls, (2) patients with IFG and (3) patients with new-onset, uncomplicated T2D (<2 years since diagnosis) were enrolled. Circulating miRNAs were extracted from blood serum and profiled through real-time PCR on a commercial 384 well-array, containing spotted forward primers for 372 miRNAs. Data analysis was performed by using the online data analysis software GeneGlobe and normalized by the global Ct mean method. Results-Of the 372 analyzed miRNAs, 33 showed a considerably different expression in IFG and new-onset T2D compared to healthy euglycemic controls, with 2 of them down-regulated and 31 up-regulated. Stringent analysis conditions, using a differential fold regulation threshold ≥ 10, revealed that nine miRNAs (hsa-miR-3610, hsa-miR-3200-5p, hsa-miR-4651, hsa-miR-3135b, hsa-miR-1281, hsa-miR-4301, hsa-miR-195-5p, hsa-miR-523-5p and hsa-let-7a-5p) showed a specific increase in new-onset T2D patients compared to IFG patients, suggesting their possible role as early biomarkers of progression from prediabetes to T2D. Moreover, by conventional fold regulation thresholds of ±2, hsa-miR-146a-5p was down-regulated and miR-1225-3p up-regulated in new-onset T2D patients only. Whereas hsa-miR-146a-5p has a well-known role in glucose metabolism, insulin resistance and T2D complications, no association between hsa-miR-1225-3p and T2D has been previously reported. Bioinformatic and computational analysis predict a role of hsa-miR-1225-3p in the pathogenesis of T2D through the interaction with MAP3K1 and HMGA1. Conclusions-The outcomes of this study could aid in the identification and characterization of circulating miRNAs as potential novel biomarkers for the early diagnosis of T2D and may serve as a proof-of-concept for future mechanistic investigations.

miR-378-3p Knockdown Recapitulates Many of the Features of Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are clonal neoplasms of the hematopoietic stem cell that result in aberrant differentiation of hematopoietic lineages caused by a wide range of underlying genetic, epigenetic, and other causes. Despite the myriad origins, a recognizable MDS phenotype has been associated with miRNA aberrant expression. A model of aberrant myeloid maturation that mimics MDS was generated using a stable knockdown of miR-378-3p. This model exhibited a transcriptional profile indicating aberrant maturation and function, immunophenotypic and morphologic dysplasia, and aberrant growth that characterizes MDS. Moreover, aberrant signal transduction in response to stimulation specific to the stage of myeloid maturation as indicated by CyTOF mass cytometry was similar to that found in samples from patients with MDS. The aberrant signaling, immunophenotypic changes, cellular growth, and colony formation ability seen in this myeloid model could be reversed with azacytidine, albeit without significant improvement of neutrophil function.

Clinical Applications of MicroRNAs in Acute Myeloid Leukemia: A Mini-Review

MicroRNAs (miRs) are short non-coding RNAs, typically 18-25 nucleotides in length, that are critically important, through their direct effects on target mRNAs, in a variety of cellular processes including cell differentiation, proliferation and survival. Dysregulated miR expression has been identified in numerous cancer types including acute myeloid leukemia (AML). From a clinical standpoint, several miRs have been shown to associate with prognosis in AML patients. Furthermore, they also carry the potential to be used as biomarkers and to inform medical decision making. In addition, several preclinical studies have provided strong rationale to develop novel therapeutic strategies to target miRs in AML. This review will focus on potential clinical applications of miRs in adult AML and will discuss unique miR signatures in specific AML subtypes, their role in prognostication and response to therapy, as well as miRs that are promising therapeutic targets and ongoing clinical trials directed towards targeting clinically relevant miRs in AML that could allow for improvements in current treatment strategies.

MiR-221 Expression Level Correlates with Insulin-Induced Doxorubicin Resistance in MCF-7 Breast Cancer Cells

Objective

Insulin induces anti-cancer drugs resistance in tumor cells. However, the mechanism by which insulin induces its drug resistance effects is not clear. In the present study, the expression of miR-221 in insulin-treated MCF-7 cells in response to the anti-cancer drug doxorubicin, was investigated.

Materials and Methods

In this experimental study, cell viability was evaluated using MTT (3-[4,5 dimethylthiazol-2- yl]-2,5-diphenyl tetrazolium bromide) assay. The expression level of miR-221 was determined by real time polymerase chain reaction (RT-PCR). Furthermore, the expression of insulin receptor (IR) and cleaved caspase-3 protein was assessed by Western blotting.

Results

The results showed that treatment of the MCF-7 cells with insulin reduced the anti-cancer effects of doxorubicin. Viability of naive and insulin-treated cells following doxorubicin (DOX) treatment was 62.9 ± 5.7% and 79 ± 7.2%, respectively. Furthermore, the expression of miR-221 in insulin-treated cells was significantly increased (2.6 ± 0.37-fold change) as compared with the control group. A significant decrease (26%) in the expression of caspase-3 protein and a significant increase (24%) in IR were observed in insulin-induced drug resistant MCF-7 cells as compared to the naive cells.

Conclusion

Together, the data showed a positive correlation between the expression of miR-221 and IR expression, but a negative correlation with caspase3 expression, in insulin-induced drug resistant MCF-7 breast cancer cells. This could suggest a new mechanism for the role of miR-221 in cancer drugs resistance induced by insulin.

miR-324-3p and miR-508-5p expression levels could serve as potential diagnostic and multidrug-resistant biomarkers in childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is one of the most frequent hematological malignancies in children, representing approximately 25 % of all pediatric cancers. Despite striking advances in ALL treatments, a small population of patients does not still respond to chemotherapy, raising the number of deaths in children. ABC transporters are one of the major causes of multidrug resistance (MDR) in cancers and overexpression of ABCA3 is directly associated with increased chemo-resistance in pediatric ALL. Here, we aimed to identify the microRNAs (miRNAs) which may regulate the expression of ABCA3 in childhood ALL. Bone marrow samples from a total of 50 ALLs and 59 controls were collected and after in silico and literature search, miR-324-3p and miR-508-5p were nominated from a list of putative miRNAs targeting ABCA3. Our qPCR analysis showed a low expression profile of selected miRNAs in pediatric ALL patients compared with non-cancer controls. Furthermore, we found that both miR-324-3p and miR-508-5p were significantly differentially expressed between patients with positive and negative minimal residual disease (MRD + vs MRD-) after one year of chemotherapy while only miR-508-5p was underexpressed in relapsed ALL patients. Additionally, a negative correlation was identified between the expression of these two miRNAs and ABCA3, supporting the regulatory effect of them on drug resistance through interacting with ABCA3. Overall, we suggested miR-324-3p and miR-508-5p as potential diagnostic and drug-resistant biomarkers in pediatric ALL. Moreover, our findings presented miR-508-5p to behave as a promising relapsed indicator in childhood ALL which can be applied in the development of novel therapeutic strategies.

Profiling 25 Bone Marrow microRNAs in Acute Leukemias and Secondary Nonleukemic Hematopoietic Conditions

Introduction: The standard treatment of acute leukemias (AL) is becoming more efficacious and more selective toward the mechanisms via which to suppress hematologic cancers. This tendency in hematology imposes additional requirements on the identification of molecular-genetic features of tumor clones. MicroRNA (miRNA, miR) expression levels correlate with cytogenetic and molecular subtypes of acute leukemias recognized by classification systems. The aim of this work is analyzing the miRNA expression profiles in acute myeloblastic leukemia (AML) and acute lymphoblastic leukemia (ALL) and hematopoietic conditions induced by non-tumor pathologies (NTP). Methods: A total of 114 cytological samples obtained by sternal puncture and aspiration biopsy of bone marrow (22 ALLs, 44 AMLs, and 48 NTPs) were analyzed by real-time PCR regarding preselected 25 miRNAs. For the classification of the samples, logistic regression was used with balancing of comparison group weights. Results: Our results indicated potential feasibility of (i) differentiating ALL+AML from a nontumor hematopoietic pathology with 93% sensitivity and 92% specificity using miR-150:miR-21, miR-20a:miR-221, and miR-24:nf3 (where nf3 is a normalization factor calculated from threshold cycle values of miR-103a, miR-191, and miR-378); (ii) diagnosing ALL with 81% sensitivity and 81% specificity using miR-181b:miR-100, miR-223:miR-124, and miR-24:nf3; and (iii) diagnosing AML with 81% sensitivity and 84% specificity using miR-150:miR-221, miR-100:miR-24, and miR-181a:miR-191. Conclusion: The results presented herein allow the miRNA expression profile to de used for differentiation between AL and NTP, no matter what AL subtype.

Diagnosis and treatment of lymphomas in the era of epigenetics

Lymphomas represent a heterogeneous group of cancers characterized by clonal lymphoproliferation. Over the past decades, frequent epigenetic dysregulations have been identified in hematologic malignancies including lymphomas. Many of these impairments occur in genes with established roles and well-known functions in the regulation and maintenance of the epigenome. In hematopoietic cells, these dysfunctions can result in abnormal DNA methylation, erroneous chromatin state and/or altered miRNA expression, affecting many different cellular functions. Nowadays, it is evident that epigenetic dysregulations in lymphoid neoplasms are mainly caused by genetic alterations in genes encoding for enzymes responsible for histone or chromatin modifications. We summarize herein the recent epigenetic modifiers findings in lymphomas. We focus also on the most commonly mutated epigenetic regulators and emphasize on actual epigenetic therapies.

MicroRNA Signatures in Blood or Bone Marrow Distinguish Subtypes of Pediatric Acute Lymphoblastic Leukemia

OncomiRs are microRNAs that are associated with early onset of specific cancers. To identify microRNAs involved in pediatric acute lymphoblastic leukemia (ALL) subtypes T-ALL and B-ALL, peripheral blood and bone marrow samples were independently subjected to microarray analysis using two different high-fidelity array platforms. The unique and common gene signatures from both arrays were validated by TaqMan individual assays in 100 pediatric ALL samples. Survival studies were carried out in the test set and validation set with 50 randomly selected samples in each set. MicroRNA expression profile revealed characteristic signatures for distinguishing T and B lineages and identified 51 novel microRNAs in pediatric ALL. Interestingly, the present study also revealed endogenous similarities and differences between blood and bone marrow within each ALL subtype. When Cox regression analysis was carried out with these identified microRNAs, 11 of them exhibited expression levels significantly correlated with survival. Validation of some of the common and relevant microRNAs from both arrays showed that their targets are involved in key oncogenic signaling pathways. Thus, this study suggests that microRNAs have the potential to become important diagnostic tools for identification and monitoring clinical outcomes in ALL patients.

miR-206 family is important for mitochondrial and muscle function, but not essential for myogenesis in vitro

miR-206, miR-1a-1, and miR-1a-2 are induced during differentiation of skeletal myoblasts and promote myogenesis in vitro. miR-206 is required for skeletal muscle regeneration in vivo. Although this miRNA family is hypothesized to play an essential role in differentiation, a triple knock-out (tKO) of the three genes has not been done to test this hypothesis. We report that tKO C2C12 myoblasts generated using CRISPR/Cas9 method differentiate despite the expected derepression of the miRNA targets. Surprisingly, their mitochondrial function is diminished. tKO mice demonstrate partial embryonic lethality, most likely due to the role of miR-1a in cardiac muscle differentiation. Two tKO mice survive and grow normally to adulthood with smaller myofiber diameter, diminished physical performance, and an increase in PAX7 positive satellite cells. Thus, unlike other miRNAs important in other differentiation pathways, the miR-206 family is not absolutely essential for myogenesis and is instead a modulator of optimal differentiation of skeletal myoblasts.

Expression and Significance of MicroRNA155 in Serum of Patients with Cerebral Small Vessel Disease

Objective

This study aimed to investigate the changes and significance of microRNA155 levels in serum of patients with cerebral small vessel disease (CSVD).

Methods

Thirty patients with CSVD who met the inclusion criteria were selected and divided into eight patients with lacunar infarction (LI) group and 22 patients with multiple lacunar infarction (MLI) combined with white matter lesions (WML) group according to the results of head magnetic resonance imaging (MRI). Thirty samples from healthy volunteers without abnormalities after head MRI examination were selected as the control group. The levels of serum microRNA155 in each group were determined by real-time polymerase chain reaction, and the correlation between microRNA155 in the serum of patients with CSVD and the increase of imaging lesions was analyzed by Spearman correlation analysis.

Results

Compared with the control group, the serum microRNA155 level in the LI group, MLI combined with WML group increased, the difference was statistically significant (p<0.05); serum microRNA155 level was positively correlated with the increase of imaging lesions (p<0.05).

Conclusion

The change of serum microRNA155 level in patients with CSVD may be one of its self-protection mechanisms, and the intensity of this self-protection mechanism is positively correlated with the number of CSVD lesions.

miRNAs as Influencers of Cell-Cell Communication in Tumor Microenvironment

microRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at the posttranscriptional level, inducing the degradation of the target mRNA or translational repression. MiRNAs are involved in the control of a multiplicity of biological processes, and their absence or altered expression has been associated with a variety of human diseases, including cancer. Recently, extracellular miRNAs (ECmiRNAs) have been described as mediators of intercellular communication in multiple contexts, including tumor microenvironment. Cancer cells cooperate with stromal cells and elements of the extracellular matrix (ECM) to establish a comfortable niche to grow, to evade the immune system, and to expand. Within the tumor microenvironment, cells release ECmiRNAs and other factors in order to influence and hijack the physiological processes of surrounding cells, fostering tumor progression. Here, we discuss the role of miRNAs in the pathogenesis of multicomplex diseases, such as Alzheimer’s disease, obesity, and cancer, focusing on the contribution of both intracellular miRNAs, and of released ECmiRNAs in the establishment and development of cancer niche. We also review growing evidence suggesting the use of miRNAs as novel targets or potential tools for therapeutic applications.

Transcriptome analysis identifies key regulators and networks in Acute myeloid leukemia

OBJECTIVES

Acute myeloid leukemia (AML) is a heterogeneous and highly recurrent hematological malignancy. Studies have shown an association between microRNAs and drive genes in AMLs. However, the regulatory roles of miRNAs in AML and how they act on downstream targets and the signaling pathway has been little studied.

METHODS

As to understand the mechanism of mRNA-miRNA interaction in the blood malignancy from a large scale of transcriptomic sequencing studies, we applied a comprehensive miRNA-mRNA association, co-expression gene network and ingenuity pathway analysis using TCGA AML datasets.

RESULTS

Our results showed that his-mir-335 was a critical regulatory of homeobox A gene family. PBX3, KAT6A, MEIS1, and COMMD3-BMI1 were predicted as top transcription regulators in the regulatory network of the HOXA family. The most significantly enriched functions were cell growth, proliferation, and survival in the mRNA-miRNA network.

CONCLUSION

Our work revealed that regulation of the HOXA gene family and its regulation played an important role in the development of AML.

Non-coding RNAs in Natural Killer/T-Cell Lymphoma

Natural killer/T-cell lymphoma (NKTCL) is a rare and aggressive subtype of non-Hodgkin's lymphoma that is associated with a poor outcome. Non-coding RNAs (ncRNAs), which account for 98% of human RNAs, lack the function of encoding proteins but instead have the important function of regulating gene expression, including transcription, translation, RNA splicing, editing, and turnover. However, the roles and mechanisms of aberrantly expressed ncRNAs in NKTCL are not fully clear. Aberrant expressions of microRNA (miRNAs) affect the PI3K/AKT signaling pathways (miRNA-21, miRNA-155, miRNA-150, miRNA-142, miRNA-494), NF-κB (miRNA-146a, miRNA-155) and cell cycle signaling pathways to regulate cell function. Moreover, Epstein-Barr virus (EBV) encoded miRNAs and EBV oncoprotein LMP-1 regulated the expression of cellular genes that induce invasion, metastasis, cell cycle progression and cellular transformation. In addition, NKTCL-associated Long non-coding RNA (lncRNA) ZFAS1 regulated certain pathways and lncRNA MALAT1 acted as a predictive marker. This review article provides an overview of ncRNAs associated with NKTCL, summarizes the function of significantly differentially expressed hotspot non-coding RNAs that contribute to the pathogenesis, diagnoses, treatment and prognosis of NKTCL and discusses the relevance of these ncRNAs to clinical practice.

MicroRNAs as regulators and effectors of hematopoietic transcription factors

Hematopoiesis is a highly-regulated development process orchestrated by lineage-specific transcription factors that direct the generation of all mature blood cells types, including red blood cells, megakaryocytes, granulocytes, monocytes, and lymphocytes. Under homeostatic conditions, the hematopoietic system of the typical adult generates over 10¹¹ blood cells daily throughout life. In addition, hematopoiesis must be responsive to acute challenges due to blood loss or infection. MicroRNAs (miRs) cooperate with transcription factors to regulate all aspects of hematopoiesis, including stem cell maintenance, lineage selection, cell expansion, and terminal differentiation. Distinct miR expression patterns are associated with specific hematopoietic lineages and stages of differentiation and functional analyses have elucidated essential roles for miRs in regulating cell transitions, lineage selection, maturation, and function. MiRs function as downstream effectors of hematopoietic transcription factors and as upstream regulators to control transcription factor levels. Multiple miRs have been shown to play essential roles. Regulatory networks comprised of differentially expressed lineage-specific miRs and hematopoietic transcription factors are involved in controlling the quiescence and self-renewal of hematopoietic stem cells as well as proliferation and differentiation of lineage-specific progenitor cells during erythropoiesis, myelopoiesis, and lymphopoiesis. This review focuses on hematopoietic miRs that function as upstream regulators of central hematopoietic transcription factors required for normal hematopoiesis. This article is categorized under: RNA in Disease and Development > RNA in Development Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.

Differential expression of miRNAs in acute myeloid leukemia quantified by Nextgen sequencing of whole blood samples

New approaches are needed for understanding and treating acute myeloid leukemia (AML). MicroRNAs (miRs) are important regulators of gene expression in all cells and disruption of their normal expression can lead to changes in phenotype of a cell, in particular the emergence of a leukemic clone. We collected peripheral blood samples from 10 adult patients with newly diagnosed AML, prior to induction chemotherapy, and 9 controls. Two and a half ml of whole blood was collected in Paxgene RNA tubes. MiRNA was purified using RNeasy mini column (Qiagen). We sequenced approximately 1000 miRs from each of 10 AML patients and 9 controls. In subset analysis, patients with NPM1 and FLT3 mutations showed the greatest number of miRNAs (63) with expression levels that differed from control with adjusted p-value of 0.05 or less. Some of these miRs have been described previously in association with leukemia, but many are new. Our approach of global sequencing of miRs as opposed to microarray analysis removes the bias regarding which miRs to assay and has demonstrated discovery of new associations of miRs with AML. Another strength of our approach is that sequencing miRs is specific for the 5p or 3p strand of the gene, greatly narrowing the proposed target genes to study further. Our study provides new information about the molecular changes that lead to evolution of the leukemic clone and offers new possibilities for monitoring relapse and developing new treatment strategies.

miR‑155 mediates inflammatory injury of hippocampal neuronal cells via the activation of microglia

MicroRNA (miR)-155 has a crucial role in various cellular functions, including differentiation of hematopoietic cells, immunization, inflammation and cardiovascular diseases. The present study aimed to investigate the roles and mechanisms of miR-155 in treatment-resistant depression (TRD). A Cell Counting Kit-8 assay and flow cytometry were performed to assess the cell viability and apoptosis of microglial cells, respectively. Western blotting and reverse transcription-quantitative polymerase chain reaction assays were used to evaluate the associated protein and mRNA expression, respectively. The results revealed that miR-155 reduced the cell viability of BV-2 microglial cells, and miR-155 enhanced the expression levels of pro-inflammatory cytokines in BV-2 microglial cells. Furthermore, conditioned medium from miR-155-treated microglia decreased the cell viability of HT22 hippocampal cells. miR-155-treated microglia increased the apoptosis of neuronal hippocampal cells by modulating the expression levels of apoptosis regulator Bax, apoptosis regulator Bcl-2, pro-caspase-3 and cleaved-caspase-3. The cell cycle distribution was disrupted by miR-155-treated microglia through induction of S phase arrest. Furthermore, the overexpression of suppressor of cytokine signaling 1 reversed the pro-apoptotic effect of activated microglia on hippocampal neuronal cells. In conclusion, the present results suggested that miR-155 mediated the inflammatory injury in hippocampal neuronal cells by activating the microglial cells. The potential effects of miR-155 on the activation of microglial cells suggest that miR-155 may be an effective target for TRD therapies.

High expression of MiR-98 is a good prognostic factor in acute myeloid leukemia patients treated with chemotherapy alone

It has been demonstrated that microRNA-98 (miR-98) is dysregulated in multiple types of solid tumors, but its expression and impact in acute myeloid leukemia (AML) is unclear. To explore the prognostic role of miR-98 in AML, 164 AML patients with the miR-98 expression data were extracted from The Cancer Genome Atlas (TCGA) database and enrolled in this study. First, patients were divided into chemotherapy-only (chemotherapy) group and allogeneic hematopoietic stem cell transplant (allo-HSCT) group. Each group was then divided in two groups by the median expression level of miR-98. In chemotherapy group, high miR-98 expression was associated with longer event-free survival (EFS, P = 0.003) and overall survival (OS, P = 0.004), but in allo-HSCT group, EFS and OS were not significantly different between high and low miR-98 expressers. Second, All patients were divided in two groups by the median expression level of miR-98. In low miR-98 expressers, those treated with allo-HSCT had longer EFS (P = 0.001) and OS (P < 0.001) than chemotherapy, but in high miR-98 expressers, survival was independent from treatment modalities. Gene ontology enrichment analysis indicated that the genes associated with miR-98 expression were mainly concentrated in “definitive hemopoiesis”, “negative regulation of myeloid cell differentiation” and “signaling pathways regulating pluripotency of stem cells” pathways. In conclusion, our results indicated that high miR-98 expression confers good prognosis in AML patients treated with chemotherapy alone. Patients with low miR-98 expression may benefit from allo-HSCT.

Small RNA sequencing profiles of mir-181 and mir-221, the most relevant microRNAs in acute myeloid leukemia

BACKGROUND/AIMS

To evaluate and select microRNAs relevant to acute myeloid leukemia (AML) pathogenesis, we analyzed differential microRNA expression by quantitative small RNA next-generation sequencing using duplicate marrow samples from individual AML patients.

METHODS

For this study, we obtained paired marrow samples at two different time points (initial diagnosis and first complete remission status) in patients with AML. Bone marrow microRNAs were profiled by next-generation small RNA sequencing. Quantification of microRNA expression was performed by counting aligned reads to microRNA genes.

RESULTS

Among 38 samples (32 paired samples from 16 AML patients and 6 normal marrow controls), 27 were eligible for sequencing. Small RNA sequencing showed that 12 microRNAs were selectively expressed at higher levels in AML patients than in normal controls. Among these 12 microRNAs, mir-181, mir-221, and mir-3154 were more highly expressed at initial AML diagnosis as compared to first complete remission. Significant correlations were found between higher expression levels of mir-221, mir-146, and mir-155 and higher marrow blast counts.

CONCLUSION

Our results demonstrate that mir-221 and mir-181 are selectively enriched in AML marrow and reflect disease activity. mir-3154 is a novel microRNA that is relevant to AML but needs further validation.

Hsa_circ_101280 promotes hepatocellular carcinoma by regulating miR-375/JAK2

In this study, we sought to predict the effects of a certain circular RNA (circRNA), hsa_circ_101280 (also known as hsa_circ_0100929 and hsa_circ_SLAIN1), on hepatocellular carcinoma (HCC) cells and to determine the potential mechanism. After screening differentially expressed circRNAs in HCC tissues through Gene Expression Omnibus data analysis, hsa_circ_101280 was found to be highly expressed, and its high expression was verified in HCC cell lines with qRT-PCR along with the low expression of its downstream miRNA miR-375. Colony formation and flow cytometry assays showed that both hsa_circ_101280 silencing and miR-375 overexpression restrained proliferation and promoted apoptosis in HCC cells. JAK2 was identified as a downstream mRNA target of miR-375 by RNA pull-down and dual-luciferase reporter gene assays, its expression in HCC cell lines were positively regulated by hsa_circ_101280 and negatively by miR-375 expression. Furthermore, the silencing of hsa_circ_101280 significantly inhibited the growth of HCC xenografts in nude mice, with the downregulated expression of JAK2. Overall, both the in vitro and in vivo studies revealed that hsa_circ_101280 largely facilitated the tumorigenesis of HCC, characterized by the promoted proliferation and suppressed apoptosis of HCC cells, by sponging miR-375 and upregulating JAK2.

MicroRNAs in Autoimmunity and Hematological Malignancies

Autoimmunity and hematological malignancies are often concomitant in patients. A causal bidirectional relationship exists between them. Loss of immunological tolerance with inappropriate activation of the immune system, likely due to environmental and genetic factors, can represent a breeding ground for the appearance of cancer cells and, on the other hand, blood cancers are characterized by imbalanced immune cell subsets that could support the development of the autoimmune clone. Considerable effort has been made for understanding the proteins that have a relevant role in both processes; however, literature advances demonstrate that microRNAs (miRNAs) surface as the epigenetic regulators of those proteins and control networks linked to both autoimmunity and hematological malignancies. Here we review the most up-to-date findings regarding the miRNA-based molecular mechanisms that underpin autoimmunity and hematological malignancies.

Dysregulation of EZH2/miR-138 axis contributes to drug resistance in multiple myeloma by downregulating RBPMS

EZH2 is highly expressed in multiple myeloma (MM). However, the molecular mechanisms underlying EZH2 overexpression and its role in drug resistance of MM remain undefined. Here we show that EZH2 is upregulated in drug-resistant MM cells and its aberrant overexpression is associated with poor prognosis of MM patients. Overexpression of EZH2 in parental MM cells renders them resistant to anti-myeloma drugs and suppression of EZH2 displays the opposite effects. Using miRNA target scan algorithms, we identify miR-138 as a regulator of EZH2, which is conversely repressed by EZH2-induced H3K27 trimethylation in MM-resistant cell lines and primary tumor cells. Analysis of ChIP-seq dataset and H3K27me3 ChIP reveals that RBPMS is a direct and functionally relevant target of EZH2. RBPMS silencing confers resistance to MM cells and restoration of RBPMS by miR-138 overexpression re-sensitizes the resistant cells to drug. Importantly, in vivo delivery of miR-138 mimics or pharmacological inhibitor of EZH2 in combination with a proteasome inhibitor, bortezomib, induces significant regression of tumors in xenograft model. This study establishes EZH2/miR-138 axis as a potential therapeutic target for MM.

MicroRNA fingerprints in juvenile myelomonocytic leukemia (JMML) identified miR-150-5p as a tumor suppressor and potential target for treatment

Juvenile myelomonocytic leukemia (JMML) is an aggressive leukemia of early childhood characterized by aberrant proliferation of myelomonocytic cells and hypersensitivity to GM-CSF stimulation. Mutually exclusive mutations in the RAS/ERK pathway genes such as PTPN11, NRAS, KRAS, CBL, or NF1 are found in ~90% of the cases. These mutations give rise to disease at least in part by activating STAT5 through phosphorylation and by promoting cell growth. MicroRNAs (miRs) are small non-coding RNAs that regulate gene expression, which are often deregulated in leukemia. However, little is known about their role in JMML. Here, we report distinctive miR expression signatures associated with the molecular subgroups of JMML. Among the downregulated miRs in JMML, miR-150-5p was found to target STAT5b, a gene which is often over-activated in JMML, and contributes to the characteristic aberrant signaling of this disorder. Moreover, loss of miR-150-5p and upregulation of STAT5b expression were also identified in a murine model of JMML. Ectopic overexpression of miR-150-5p in mononuclear cells from three JMML patients significantly decreased cell proliferation. Altogether, our data indicate that miR expression is deregulated in JMML and may play a role in the pathogenesis of this disorder by modulating key effectors of cytokine receptor pathways.

Anti-leukemic activity of microRNA-26a in a chronic lymphocytic leukemia mouse model

Dysregulation of microRNAs (miRNAs) plays an important role in the pathogenesis of chronic lymphocytic leukemia (CLL). The Eμ-TCL1 transgenic mouse develops a form of leukemia that is similar to the aggressive type of human B-CLL, and this valuable model has been widely used for testing novel therapeutic approaches. Here, we adopted this model to investigate the potential effects of miR-26a, miR-130an and antimiR-155 in CLL therapy. Improved delivery of miRNA molecules into CLL cells was obtained by developing a novel system based on lipid nanoparticles conjugated with an anti-CD38 monoclonal antibody. This methodology has proven to be highly effective in delivering miRNA molecules into leukemic cells. Short- and long-term experiments showed that miR-26a, miR-130a and anti-miR-155 increased apoptosis after in vitro and in vivo treatment. Of this miRNA panel, miR-26a was the most effective in reducing leukemic cell expansion. Following long-term treatment, apoptosis was readily detectable by analyzing cleavage of PARP and caspase-7. These effects could be directly attributed to miR-26a, as confirmed by significant downregulation of its proven targets, namely cyclin-dependent kinase 6 and Mcl1. The results of this study are relevant to two distinct areas. The first is related to the design of a technical strategy and to the selection of CD38 as a molecular target on CLL cells, both consenting efficient and specific intracellular transfer of miRNA. The original scientific finding inferred from the above approach is that miR-26a can elicit in vivo anti-leukemic activities mediated by increased apoptosis.

Interplay of transcription factors and microRNAs during embryonic hematopoiesis

Hematopoietic stem cells (HSCs), which are localized in the bone marrow of adult mammals, come from hematopoietic endothelium during embryonic stages. Although the basic processes of HSC generation and differentiation have been described in the past, the epigenetic regulation of embryonic hematopoiesis remains to be fully described. Here, by utilizing an in vitro differentiation system of mouse embryonic stem cells (ESCs), we identified more than 20 microRNAs that were highly enriched in embryonic hematopoietic cells, including some (e.g. miR-10b, miR-15b, and miR-27a) with previously unknown functions in blood formation. Luciferase and gene expression assays further revealed combinational binding and regulation of these microRNAs by key transcription factors in blood cells. Finally, bioinformatics and functional analyses supported an interactive regulatory control between transcription factors and microRNAs in hematopoiesis.

MiRNA182 regulates percentage of myeloid and erythroid cells in chronic myeloid leukemia

The deregulation of lineage control programs is often associated with the progression of haematological malignancies. The molecular regulators of lineage choices in the context of tyrosine kinase inhibitor (TKI) resistance remain poorly understood in chronic myeloid leukemia (CML). To find a potential molecular regulator contributing to lineage distribution and TKI resistance, we undertook an RNA-sequencing approach for identifying microRNAs (miRNAs). Following an unbiased screen, elevated miRNA182-5p levels were detected in Bcr-Abl-inhibited K562 cells (CML blast crisis cell line) and in a panel of CML patients. Earlier, miRNA182-5p upregulation was reported in several solid tumours and haematological malignancies. We undertook a strategy involving transient modulation and CRISPR/Cas9 (clustered regularly interspersed short palindromic repeats)-mediated knockout of the MIR182 locus in CML cells. The lineage contribution was assessed by methylcellulose colony formation assay. The transient modulation of miRNA182-5p revealed a biased phenotype. Strikingly, Δ182 cells (homozygous deletion of MIR182 locus) produced a marked shift in lineage distribution. The phenotype was rescued by ectopic expression of miRNA182-5p in Δ182 cells. A bioinformatic analysis and Hes1 modulation data suggested that Hes1 could be a putative target of miRNA182-5p. A reciprocal relationship between miRNA182-5p and Hes1 was seen in the context of TK inhibition. In conclusion, we reveal a key role for miRNA182-5p in restricting the myeloid development of leukemic cells. We propose that the Δ182 cell line will be valuable in designing experiments for next-generation pharmacological interventions.

Nuclear microRNAs in normal hemopoiesis and cancer

Since the discovery of microRNAs (miRNAs) in the early 1990s, these small molecules have been increasingly recognized as key players in the regulation of critical biological processes. They have also been implicated in many diverse human diseases. The canonical function of miRNAs is to target the 3′ untranslated region (3′ UTR) of cytoplasmic messenger RNA to post-transcriptionally regulate mRNA and protein levels. It has now been shown that miRNAs can also bind to the promoter regions of genes or primary miRNA transcripts to regulate gene expression. Such observations have indicated the presence of miRNAs in the nucleus and implied additional non-canonical functions. Nevertheless, the role(s) of nuclear miRNAs in normal hemopoiesis and cancer remains elusive despite a burgeoning literature. Herein, we review current knowledge concerning the abundance and/or functions of nuclear miRNAs during blood cell development and cancer biology. We also discuss ongoing challenges in order to provoke further studies into identifying key roles for nuclear miRNAs in the development of other cell lineages and human cancers.

miR-539 as a key negative regulator of the MEK pathway in myocardial infarction

BACKGROUND

Myocardial infarction is one of the most common causes of death, and the number of individuals at risk is increasing. A rapid and accurate differential diagnosis of myocardial infarction is crucial for timely interventions and for improvement of the prognosis. However, it is difficult to achieve using current methods. To better manage this condition, improved tools for risk prediction, including more accurate biomarkers, are needed.

METHODS

We studied the expression of microRNA-539 (miR-539) and of MEK protein using a rat model of myocardial infarction.

RESULTS

The results of our experiments demonstrated an increase in the expression of miR-539 and a decrease in the expression of MEK. Furthermore, we observed that miR-539 inhibited the expression of MEK through targeting of the 3'UTR of MEK; this led not only to suppressed proliferation but also to apoptosis and autophagy of H9C2 cells.

CONCLUSION

Overexpression of miR-539 plays a role in the degree of myocardial infarction. On the basis of our results, we conclude that miR-539 may be a potential therapeutic target for myocardial infarction.

miR-150 Suppresses the Proliferation and Tumorigenicity of Leukemia Stem Cells by Targeting the Nanog Signaling Pathway

Proliferation, a key feature of cancer cells, accounts for the majority of cancer-related diseases resulting in mortality. MicroRNAs (miRNAs) plays important post-transcriptional modulation roles by acting on multiple signaling pathways, but the underlying mechanism in proliferation and tumorigenicity is unclear. Here, we identified the role of miR-150 in proliferation and tumorigenicity in leukemia stem cells (LSCs; CD34+CD38- cells). miR-150 expression was significantly down-regulated in LSCs from leukemia cell lines and clinical samples. Functional assays demonstrated that increased miR-150 expression inhibited proliferation and clonal and clonogenic growth, enhanced chemosensitivity, and attenuated tumorigenic activity of LSCs in vitro. Transplantation animal studies revealed that miR-150 overexpression progressively abrogates tumor growth. Immunohistochemistry assays demonstrated that miR-150 overexpression enhanced caspase-3 level and reduced Ki-67 level. Moreover, luciferase reporter assays indicated Nanog is a direct and functional target of miR-150. Nanog silencing using small interfering RNA recapitulated anti-proliferation and tumorigenicity inhibition effects. Furthermore, miR-150 directly down-regulated the expression of other cancer stem cell factors including Notch2 and CTNNB1. These results provide insights into the specific biological behavior of miR-150 in regulating LSC proliferation and tumorigenicity. Targeting this miR-150/Nanog axis would be a helpful therapeutic strategy to treat acute myeloid leukemia.

A candidate transacting modulator of fetal hemoglobin gene expression in the Arab-Indian haplotype of sickle cell anemia

Fetal hemoglobin (HbF) levels are higher in the Arab-Indian (AI) β-globin gene haplotype of sickle cell anemia compared with African-origin haplotypes. To study genetic elements that effect HbF expression in the AI haplotype we completed whole genome sequencing in 14 Saudi AI haplotype sickle hemoglobin homozygotes-seven selected for low HbF (8.2% ± 1.3%) and seven selected for high HbF (23.5% ± 2.6%). An intronic single nucleotide polymorphism (SNP) in ANTXR1, an anthrax toxin receptor (chromosome 2p13), was associated with HbF. These results were replicated in two independent Saudi AI haplotype cohorts of 120 and 139 patients, but not in 76 Saudi Benin haplotype, 894 African origin haplotype and 44 AI haplotype patients of Indian origin, suggesting that this association is effective only in the Saudi AI haplotype background. ANTXR1 variants explained 10% of the HbF variability compared with 8% for BCL11A. These two genes had independent, additive effects on HbF and together explained about 15% of HbF variability in Saudi AI sickle cell anemia patients. ANTXR1 was expressed at mRNA and protein levels in erythroid progenitors derived from induced pluripotent stem cells (iPSCs) and CD34⁺ cells. As CD34⁺ cells matured and their HbF decreased ANTXR1 expression increased; as iPSCs differentiated and their HbF increased, ANTXR1 expression decreased. Along with elements in cis to the HbF genes, ANTXR1 contributes to the variation in HbF in Saudi AI haplotype sickle cell anemia and is the first gene in trans to HBB that is associated with HbF only in carriers of the Saudi AI haplotype. Am. J. Hematol. 91:1118-1122, 2016. © 2016 Wiley Periodicals, Inc.

XBP1 splicing triggers miR-150 transfer from smooth muscle cells to endothelial cells via extracellular vesicles

The interaction between endothelial cells (ECs) and smooth muscle cells (SMCs) plays a critical role in the maintenance of vessel wall homeostasis. The X-box binding protein 1 (XBP1) plays an important role in EC and SMC cellular functions. However, whether XBP1 is involved in EC-SMC interaction remains unclear. In this study, In vivo experiments with hindlimb ischemia models revealed that XBP1 deficiency in SMCs significantly attenuated angiogenesis in ischemic tissues, therefore retarded the foot blood perfusion recovery. In vitro studies indicated that either overexpression of the spliced XBP1 or treatment with platelet derived growth factor-BB up-regulated miR-150 expression and secretion via extracellular vesicles (EVs). The XBP1 splicing-mediated up-regulation of miR-150 might be due to increased stability. The SMC-derived EVs could trigger EC migration, which was abolished by miR-150 knockdown in SMCs, suggesting miR-150 is responsible for SMC-stimulated EC migration. The SMC-derived miR-150-containing EVs or premiR-150 transfection increased vascular endothelial growth factor (VEGF)-A mRNA and secretion in ECs. Both inhibitors SU5416 and LY294002 attenuated EVs-induced EC migration. This study demonstrates that XBP1 splicing in SMCs can control EC migration via SMC derived EVs-mediated miR-150 transfer and miR-150-driven VEGF-A/VEGFR/PI3K/Akt pathway activation, thereby modulating the maintenance of vessel wall homeostasis.

Epigenetic role of miRNAs in normal and leukemic hematopoiesis

Hematopoiesis is a regulated multistep process, whereby transcriptional and epigenetic events contribute to progenitor fate determination. miRNAs have emerged as key players in hematopoietic cell development, differentiation and malignant transformation. From embryonic development through to adult life, miRNAs cooperate with, or are regulated, by epigenetic factors. Moreover, recent findings suggest that they contribute to chromatin structural modification, and the functional relevance of this 'epigenetic-miRNA axis' will be discussed in this article. Finally, emerging evidence has highlighted that miRNAs have functional control in human hematopoietic cells, involving targeted recruitment of epigenetic complexes to evolutionarily conserved complementary genomic loci. We propose the existence of epigenetic-miRNA loops that are able to organize the whole gene expression profile in hematopoietic cells.

MicroRNA-mRNA Pairs Associated with Outcome in AML: From In Vitro Cell-Based Studies to AML Patients

Cytarabine is the primary chemotherapeutic agent used for treatment of acute myeloid leukemia (AML). Disease relapse after initial remission remains one of the most pressing therapeutic challenges in the treatment of AML. Relapsed disease is often resistant to cytarabine and subsequent salvage therapy is ineffective. Recent studies have shown that some microRNAs (miRNAs) are associated with prognosis, but have not yet explored the role of miRNAs in cellular response to cytarabine. We identified 20 miRNAs that associate with the in vitro cytarabine chemo-sensitivity or apoptotic response of eight AML cell lines. Out of the 20 miRNAs, data on 18 miRNAs was available in AML patients from The Cancer Genome Atlas database. Our stepwise-integrated analyses (step 1 - miRNA-target mRNA that were significantly correlated in AML patients; step 2 - mRNAs from step 1 with significant association with overall survival (OS)) identified 23 unique miRNA-mRNA pairs predictive of OS in AML patients. As expected HOX genes (HOXA9, HOXB7, and HOXA10) were identified to be regulated by miRs as well as predictive of worse OS. Additionally, miR107-Myb, miR-378-granzyme B involved in granzyme signaling and miR10a-MAP4K4 were identified to be predictive of outcome through integrated analysis. Although additional functional validations to establish clinical/pharmacologic importance of miRNA-mRNA pairs are needed, our results from RNA electrophoretic mobility shift assay confirmed binding of miR-10a, miR-378, and miR-107 with their target genes GALNT1, GZMB, and MYB, respectively. Integration of pathogenic and pharmacologically significant miRNAs and miRNA-mRNA relationships identified in our study opens up opportunities for development of targeted/miRNA-directed therapies.

Histone demethylase RBP2 decreases miR-21 in blast crisis of chronic myeloid leukemia

Chronic myeloid leukemia in the blastic phase (CML-BP) responds poorly to clinical treatments and is usually fatal. In this study, we found that the histone H3 lysine 4 (H3K4) demethylase RBP2 (also called JARID1A and KDM5A) is underexpressed in CML-BP. The RBP2 histone demethylase stimulates leukemia cell differentiation and inhibits cell proliferation. We identified miR-21 was directly downregulated by RBP2 and found that miR-21 downregulated PDCD4 expression in leukemia cells. By binding to miR-21 promoter and by demethylating of trimethylated H3K4 at the miR-21 locus, RBP2 downregulated miR-21 expression. This in turn activated PDCD4. In conclusion, RBP2 epigenetically downregulated miR-21 in blast transformation of CML.

MicroRNA-363 targets myosin 1B to reduce cellular migration in head and neck cancer

Background

Squamous cell carcinoma of the head and neck (SCCHN) remains a prevalent and devastating disease. Recently, there has been an increase in SCCHN cases that are associated with high-risk human papillomavirus (HPV) infection. The clinical characteristics of HPV-positive and HPV-negative SCCHN are known to be different but their molecular features are only recently beginning to emerge. MicroRNAs (miRNAs, miRs) are small, non-coding RNAs that are likely to play significant roles in cancer initiation and progression where they may act as oncogenes or tumor suppressors. Previous studies in our laboratory showed that miR-363 is overexpressed in HPV-positive compared to HPV-negative SCCHN cell lines, and the HPV type 16-E6 oncoprotein upregulates miR-363 in SCCHN cell lines. However, the functional role of miR-363 in SCCHN in the context of HPV infection remains to be elucidated.

Methods

We analyzed miR-363 levels in SCCHN tumors with known HPV-status from The Cancer Genome Atlas (TCGA) and an independent cohort from our institution. Cell migration studies were conducted following the overexpression of miR-363 in HPV-negative cell lines. Bioinformatic tools and a luciferase reporter assay were utilized to confirm that miR-363 targets the 3’-UTR of myosin 1B (MYO1B). MYO1B mRNA and protein expression levels were evaluated following miR-363 overexpression in HPV-negative SCCHN cell lines. Small interfering RNA (siRNA) knockdown of MYO1B was performed to assess the phenotypic implication of reduced MYO1B expression in SCCHN cell lines.

Results

MiR-363 was found to be overexpressed in HPV-16-positive compared to the HPV-negative SCCHN tumors. Luciferase reporter assays performed in HPV-negative JHU028 cells confirmed that miR-363 targets one of its two potential binding sites in the 3’UTR of MYO1B. MYO1B mRNA and protein levels were reduced upon miR-363 overexpression in four HPV-negative SCCHN cell lines. Increased miR-363 expression or siRNA knockdown of MYO1B expression reduced Transwell migration of SCCHN cell lines, indicating that the miR-363-induced migration attenuation of SCCHN cells may act through MYO1B downregulation.

Conclusions

These findings demonstrate that the overexpression of miR-363 reduces cellular migration in head and neck cancer and reveal the biological relationship between miR-363, myosin 1b, and HPV-positive SCCHN.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1888-3) contains supplementary material, which is available to authorized users.

microRNA-10b Is Overexpressed and Critical for Cell Survival and Proliferation in Medulloblastoma

This study demonstrates the effects of miRNA-10b on medulloblastoma proliferation through transcriptional induction of the anti-apoptotic protein BCL2. Using a cancer specific miRNA-array, high expression of miRNA-10b in medulloblastoma cell lines compared to a normal cerebellar control was shown, and this was confirmed with real time PCR (RT-PCR). Two medulloblastoma cell lines (DAOY and UW228) were transiently transfected with control miRNA, miRNA-10b inhibitor or miRNA-10b mimic and subjected to RT-PCR, MTT, apoptosis, clonogenic assay and western blot analysis. Transfection of miRNA-10b inhibitor induced a significant down-regulation of miRNA-10b expression, inhibited proliferation, and induced apoptosis, while miRNA-10b mimic exerted an opposite effect. Inhibition of miRNA-10b abrogated the colony-forming capability of medulloblastoma cells, and markedly down-regulated the expression of BCL2. Down-regulation of BCL2 by antisense oligonucleotides or siRNA also significantly down-regulated miRNA-10b, suggesting that BCL2 is a major mediator of the effects of miRNA-10b. ABT-737 and ABT-199, potent inhibitors of BCL2, downregulated the expression of miRNA-10b and increased apoptosis. Analysis of miRNA-10b levels in 13 primary medulloblastoma samples revealed that the 2 patients with the highest levels of miRNA-10b had multiple recurrences (4.5) and died within 8 years of diagnosis, compared with the 11 patients with low levels of miRNA-10b who had a mean of 1.2 recurrences and nearly 40% long-term survival. The data presented here indicate that miRNA-10b may act as an oncomir in medulloblastoma tumorigenesis, and reveal a previously unreported mechanism with Bcl-2 as a mediator of the effects of miRNA-10b upon medulloblastoma cell survival.

MicroRNA regulation of viral immunity, latency, and carcinogenesis of selected tumor viruses and HIV

MicroRNAs (miRNAs) function as key regulators in immune responses and cancer development. In the contexts of infection with oncogenic viruses, miRNAs are engaged in viral persistence, latency establishment and maintenance, and oncogenesis. In this review, we summarize the potential roles and mechanisms of viral and cellular miRNAs in the host-pathogen interactions during infection with selected tumor viruses and HIV, which include (i) repressing viral replication and facilitating latency establishment by targeting viral transcripts, (ii) evading innate and adaptive immune responses via toll-like receptors, RIG-I-like receptors, T-cell receptor, and B-cell receptor pathways by targeting signaling molecules such as TRAF6, IRAK1, IKKε, and MyD88, as well as downstream targets including regulatory cytokines such as tumor necrosis factor α, interferon γ, interleukin 10, and transforming growth factor β, (iii) antagonizing intrinsic and extrinsic apoptosis pathways by targeting pro-apoptotic or anti-apoptotic gene transcripts such as the Bcl-2 family and caspase-3, (iv) modulating cell proliferation and survival through regulation of the Wnt, PI3K/Akt, Erk/MAPK, and Jak/STAT signaling pathways, as well as the signaling pathways triggered by viral oncoproteins such as Epstein-Barr Virus LMP1, by targeting Wnt-inhibiting factor 1, SHIP, pTEN, and SOCSs, and (v) regulating cell cycle progression by targeting cell cycle inhibitors such as p21/WAF1 and p27/KIP1. Further elucidation of the interaction between miRNAs and these key biological events will facilitate our understanding of the pathogenesis of viral latency and oncogenesis and may lead to the identification of miRNAs as novel targets for developing new therapeutic or preventive interventions.

microRNAs as Developmental Regulators

The field of miRNA biology is relatively young, but its impact on our understanding of the regulation of a wide array of cell functions is far-reaching. The importance of miRNAs in development has become nearly ubiquitous, with miRNAs contributing to development of most cells and organs. Although miRNAs are clearly interwoven into known regulatory networks that control cell development, the specific modalities by which they intersect are often quite distinct and cleverly achieved. The frequently emerging theme of feed-back and feed-forward loops to either counterbalance or reinforce the gene programs that they influence is a common thread. Many of these examples of miRNAs as developmental regulators are presently found in organs with different miRNAs and targets, whereas novel, unexpected themes emerge in the context of mouse development as we learn more about this rapidly developing area of biology.

Epigenetic landscape of acute myelogenous leukemia--moving toward personalized medicine

Acute myeloid leukemia (AML) is an aggressive hematologic cancer that is characterized by accumulation of immature myeloid cells in the blood and bone marrow. The malignant cells in AML have reduced capacity to mature fully, and often exhibit chromosomal abnormalities, defects in cell signaling, and abnormal cell cycle control. Genetic and epigenetic changes are implicated in the onset and progression of AML. While progress has been made in using genetic and epigenetic changes as prognostic features of AML, these findings have not yet been effectively translated into novel treatment strategies. Disappointingly, rates of recurrence in AML remain high and overall survival is poor. Research strategies should focus on developing a comprehensive landscape of genetic and epigenetic changes in individual patients with AML to expand the clinicians' therapeutic armamentarium and to individualize and optimize treatment.

Deregulation of DNMT1, DNMT3B and miR-29s in Burkitt lymphoma suggests novel contribution for disease pathogenesis

Methylation of CpG islands in promoter gene regions is frequently observed in lymphomas. DNA methylation is established by DNA methyltransferases (DNMTs). DNMT1 maintains methylation patterns, while DNMT3A and DNMT3B are critical for de novo DNA methylation. Little is known about the expression of DNMTs in lymphomas. DNMT3A and 3B genes can be regulated post-transcriptionally by miR-29 family. Here, we demonstrated for the first time the overexpression of DNMT1 and DNMT3B in Burkitt lymphoma (BL) tumor samples (69% and 86%, respectively). Specifically, the treatment of two BL cell lines with the DNMT inhibitor 5-aza-dC decreased DNMT1 and DNMT3B protein levels and inhibited cell growth. Additionally, miR-29a, miR-29b and miR-29c levels were significantly decreased in the BL tumor samples. Besides, the ectopic expression of miR-29a, miR-29b and miR-29c reduced the DNMT3B expression and miR-29a and miR-29b lead to increase of p16(INK4a) mRNA expression. Altogether, our data suggest that deregulation of DNMT1, DNMT3B and miR29 may be involved in BL pathogenesis.

miR-137 and miR-197 Induce Apoptosis and Suppress Tumorigenicity by Targeting MCL-1 in Multiple Myeloma

PURPOSE

Deregulation of miRNA has been implicated in the pathogenesis of multiple myeloma. We identified miR-137 and miR-197, mapped to the chromosome 1p (12)-(21) deletion region, and examined their antimyeloma activity as tumor suppressors.

EXPERIMENTAL DESIGN

The expression of miR-137/197 was examined in multiple myeloma and normal plasma cells by qRT-PCR. Functional effect of miR-137/197 was analyzed by cell viability, apoptosis, clonogenic, and migration assays. Antimyeloma activity of miR-137/197 was further evaluated in vivo by lentiviral-based or lipid-based delivery in a mouse xenograft model of multiple myeloma.

RESULTS

miR-137/197 expression was significantly lower in multiple myeloma cell lines and multiple myeloma patient samples compared with normal plasma cells. Transfection of miR-137/197 resulted in reduction of MCL-1 protein expression, as well as alteration of apoptosis-related genes, and induction of apoptosis, inhibition of viability, colony formation, and migration in multiple myeloma cells. MCL-1 was further validated as a direct target of miR-137/197. Conversely, overexpression of MCL-1 partially reverted the effect of miR-137/197. Importantly, in vivo lentiviral-mediated or intratumor delivery of miR-137/197 induced regression of tumors in murine xenograft models of multiple myeloma.

CONCLUSIONS

Our study reveals a novel role of miR-137/197 as tumor suppressors in mediating apoptosis in multiple myeloma cells by targeting MCL-1. Our findings provide a proof-of-principle that lentivirus-based or formulated synthetic miR-137/197 exerts therapeutic activity in preclinical models, and support a framework for development of miR-137/197-based treatment strategies in patients with multiple myeloma.

Long term and excessive use of 900 MHz radiofrequency radiation alter microRNA expression in brain

PURPOSE

We still do not have any information on the interaction between radiofrequency radiation (RF) and miRNA, which play paramount role in growth, differentiation, proliferation and cell death by suppressing one or more target genes. The purpose of this study was to bridge this gap by investigating effects of long-term 900 MHz mobile phone exposure on some of the miRNA in brain tissue.

MATERIALS AND METHODS

The study was carried out on 14 Wistar Albino adult male rats by dividing them into two groups: Sham (n = 7) and exposure (n = 7). Rats in the exposure group were exposed to 900 MHz RF radiation for 3 h per day (7 days a week) for 12 months (one year). The same procedure was applied to the rats in the sham group except the generator was turned off. Immediately after the last exposure, rats were sacrificed and their brains were removed. rno-miR-9-5p, rno-miR-29a-3p, rno-miR-106b-5p, rno-miR-107 and rno-miR-125a-3p in brain were investigated in detail.

RESULTS

Results revealed that long-term exposure of 900 MHz RF radiation only decreased rno-miR107 (adjP* = 0.045) value where the whole body (rms) SAR value was 0.0369 W/kg. However, our results indicated that other microRNA evaluated in this study was not altered by 900 MHz RF radiation.

CONCLUSION

900 MHz RF radiation can alter some of the miRNA, which, in turn, may lead to adverse effects. Therefore, further studies should be performed.