Distinctive microRNA signature of acute myeloid leukemia bearing cytoplasmic mutated nucleophosmin

MicroRNA‑10a enhances the metastatic potential of cervical cancer cells by targeting phosphatase and tensin homologue

Cervical cancer is one of the leading causes of cancer‑related mortality worldwide. Previously, the upregulation of microRNA (miR)‑10a has been identified in human cervical cancer. The present study firstly demonstrated that miR‑10a was markedly upregulated in primary tumor tissues in patients with positive lymph node metastasis (LN+) compared with negative (LN‑) by quantitative polymerase chain reaction. miR‑10a mimics markedly enhanced cervical cancer cell migration and invasion abilities, and accordingly the miR‑10a inhibitor suppressed those functions. Furthermore, these data suggested that the phosphatase and tensin homologue (PTEN) was inhibited by miR‑10a through an miR‑10a binding site within the 3'‑untranslated region of PTEN at the posttranscriptional level, and that miR‑10a mimics promoted nuclear translocation of β‑catenin. Therefore, it was concluded that the overexpression of miR‑10a contributes to metastasis in cervical cancer by targeting PTEN. miR‑10a may therefore be used clinically as a molecular marker for patients with cervical cancer lymph node metastasis.

The miR-29 family in hematological malignancies

BACKGROUND

MicroRNAs are short non-coding regulators of gene expression. The human miR-29 family consists of three members: miR-29a, miR-29b and miR-29c. Members of this family were found to be aberrantly expressed in various types of tumors, including hematological malignancies. This family was described to have both oncogenic and tumor suppressor features influencing various pathological processes, such as tumor growth and apoptosis. This review summarizes current knowledge about the miR-29 family in selected hematological malignancies.

CONCLUSION

Recent research of miR-29 family in hematological malignancies has proven its oncogenic as well as tumor suppressive potential. Nevertheless, the level of current evidence is not sufficient, and data remain inconclusive.

Altered expression pattern of miR-29a, miR-29b and the target genes in myeloid leukemia

Objectives

The miR-29 family have been demonstrated acting as vital tumor suppressor in multiple cancers as well as regulators in the adaptive immune system. Little is known about their role in leukemogenesis. The purpose of this study is to analyze the expression pattern of miR-29a/29b and its target genes Mcl-1 (myeloid cell leukemia sequence 1) and B-cell lymphoma 2 (Bcl-2) in myeloid leukemia.

Methods

Quantitative real-time PCR was used for detecting genes expression level in peripheral blood mononuclear cells (PBMCs) from 10 cases with newly diagnosed, untreated acute myeloid leukemia (AML) and 14 cases with newly diagnosed, untreated chronic myeloid leukemia (CML) in chronic phase, and 14 healthy individual (HI) served as controls. Correlation between the relative expression levels of different genes have been analyzed.

Results

Significant lower expression of miR-29a/29b and higher expression level of two potential target genes Bcl-2 and Mcl-1 were found in PBMCs from AML and CML patients compared with HI group. In addtion, miR-29a expression in AML was significantly lower than that in CML. Moreover, negative correlation between miR-29a/29b and its target genes have been found. While, positive correlation between relative expression level of miR-29a and miR-29b or Bcl-2 and Mcl-1 were presented in the total 38 research objects.

Conclusion

Down-regulated miR-29a and miR-29b, and accompanying up-regulated Bcl-2 and Mcl-1 are the common feature in myeloid leukemias. These data further support the role for miR-29a/29b dysregulation in myeloid leukemogenesis and the therapeutic promise of regulating miR-29a/29b expression for myeloid leukemia in the future.

MicroRNA-26a-5p and microRNA-23b-3p up-regulate peroxiredoxin III in acute myeloid leukemia

MicroRNAs (miRNAs) are small RNAs that regulate target gene expression. Using microarray-based miRNA expression profiling, we compared the miRNA expression in granulocytes from four patients with acute myeloid leukemia and four healthy controls. Thirty-four miRNAs were found to be differentially expressed, including 20 miRNAs that were up-regulated and 14 miRNAs that were down-regulated. The expression of selected miRNAs (miR-26a-5p and miR-23b-3p) was independently validated in 20 patients and 12 healthy controls. Notably, we demonstrated that peroxiredoxin III (PrxIII) is a common direct target of both miR-26a-5p and miR-23b-3p. Furthermore, these results indicate that the two decreased miRNAs could scavenge cellular reactive oxygen species (ROS) by targeting the PrxIII gene. These findings are discussed with regard to the known function of PrxIII as a ROS scavenger and the high endogenous ROS levels required for hematopoietic stem cell differentiation. These findings may potentially offer insights into the pathological relationships between miR-26a-5p, miR-23b-3p and leukemogenesis.

The role of miR-29 family members in malignant hematopoiesis

AIMS

MicroRNAs of the miR-29 family members were one of the first microRNAs identified as possible therapeutic agents in malignant hematopoiesis. The aim of our review is to summarize the current state of knowledge on miR-29 family members.

METHODS

We performed literature searches involving miR-29 family members and their relationship to individual hematological malignancies, namely acute myeloid leukemia (AML), chronic lymphoblastic leukemia (CLL) and chronic myeloid leukemia (CML). We also searched for subgroups of hematological malignancies, e.g. multiple myeloma, that are regarded as members of the acute or chronic types of leukemias.

RESULTS

A number of genes appear to be regulated by miR-29 family members in various physiological and pathological situations. In our view regulation of Tcl-1, Mcl-1 and DNA methyltransferases is relevant in case of hematological malignancies, hence these are the focus of this review. miR-29 family members also function during normal T-cell and B-cell development.

CONCLUSION

MiR-29 family members appear to govern some general features in commonly heterogenous hematological malignancies and therefore form a potential target for treatment.

Genomic characterization of acute leukemias

Over the past two decades, hematologic malignancies have been extensively evaluated due to the introduction of powerful technologies, such as conventional karyotyping, FISH analysis, gene and microRNA expression profiling, array comparative genomic hybridization and SNP arrays, and next-generation sequencing (including whole-exome sequencing and RNA-seq). These analyses have allowed for the refinement of the mechanisms underlying the leukemic transformation in several oncohematologic disorders and, more importantly, they have permitted the definition of novel prognostic algorithms aimed at stratifying patients at the onset of disease and, consequently, treating them in the most appropriate manner. Furthermore, the identification of specific molecular markers is opening the door to targeted and personalized medicine. The most important findings on novel acquisitions in the context of acute lymphoblastic leukemia of both B and T lineage and de novo acute myeloid leukemia are described in this review.

Epigenetically regulated microRNAs and their prospect in cancer diagnosis

Epigenetic alterations have been reported to deregulate the expression of many transcripts, including noncoding RNAs that have no apparent protein-coding capacity. Recently, as the result of numerous studies focused on miRNAs, novel sequencing technologies have made available the transcription profile of the entire human genome. miRNAs as drivers of tumor-suppressive and oncogenic functions have been found to be dysregulated in numerous cancer types. However, the functions of epigenetically regulated genetic elements other than protein-coding genes are still a matter of debate. In this review, the authors focus mainly on describing the epigenetic regulation of miRNAs in cancer. They also discuss the role of miRNAs as potential diagnostic and/or prognostic biomarkers.

Nephroblastomas show low expression of microR-204 and high expression of its target, the oncogenic transcription factor MEIS1

By comparing several studies we identified a possible deregulation of the transcription factors PBX2 (pre-B-cell leukemia homeobox 2) and one of its binding partners, MEIS1 (Meis homeobox 1) in nephroblastomas. The regulation of MEIS1 is complex, and its expression is known to be influenced by changes of promoter methylation and binding of microRNA-204 (miR-204). Therefore, in our study, we assessed the expression of MEIS1 and PBX2 and the factors regulating expression of MEIS1 in nephroblastomas. MEIS1 and PBX2 messenger RNA (mRNA) and protein levels were investigated by quantitative real-time-polymerase chain reaction (qRT-PCR) and immunohistochemistry. Promoter methylation of MEIS1 was evaluated using a methylation-specific PCR assay. Expression levels of miR-204 were examined by qRT-PCR. Eighteen of 21 nephroblastomas showed a high level of MEIS1 mRNA, and 22 of 26 samples had a specific nuclear protein expression. MicroRNA-204 had a statistically significantly lower expression in all nephroblastomas investigated compared with renal parenchyma, but no change of MEIS1 promoter methylation status was noted. Eleven of 23 nephroblastomas had a high expression of PBX2 mRNA, and 15 of 23 samples had a specific nuclear protein expression was noted. In our study, we demonstrated an expression of MEIS1 and its binding partner PBX2 in most nephroblastomas. The statistically significantly lower expression of miR-204 in all nephroblastomas investigated might point to an involvement of miR-204 in the regulation of MEIS1 in nephroblastomas.

miR-181b increases drug sensitivity in acute myeloid leukemia via targeting HMGB1 and Mcl-1

Multidrug resistance (MDR) remains the major cause of disease relapse and poor prognosis in adults with acute myeloid leukemia (AML). Emerging evidence shows that drug resistance not only exists against conventional chemotherapeutic drugs, but also limits the efficacy of new biological agents. Therefore, it is important to elucidate the mechanisms through which AML patients develop drug resistance. MicroRNAs have been shown to play an important role in regulating the chemotherapy resistance in AML. A detailed understanding of the mechanisms of microRNA that are clinically relevant in AML may enhance our ability to predict and overcome drug resistance. Here, we demonstrated, for the first time, that miR-181b was decreased significantly in human multidrug-resistant leukemia cells and relapsed/refractory AML patient samples. Overexpression of miR-181b increased the sensitivity of leukemia cells to cytotoxic chemotherapeutic agents and promoted drug-induced apoptosis. Moreover, miR-181b inhibited HMGB1 and Mcl-1 expression by direct binding to their 3'-untranslated regions. In addition, HMGB1 was expressed at high levels in relapsed/refractory AML patients and suppression of HMGB1 via RNA interference sensitized multidrug-resistant leukemia cells to chemotherapy and induced apoptosis. In conclusion, these results provide a strong rationale for the development of miR-181b-based therapeutic strategies for the enhancement of efficacy in AML treatment.

Expression profiling of leukemia patients: key lessons and future directions

Gene expression profiling (GEP) is a well-established indispensable tool used to study hematologic malignancies, including leukemias. Here, we summarize the insights into the molecular basis of leukemias obtained by means of GEP, focusing especially on acute myeloid leukemia (AML), one of the first diseases to be extensively studied by GEP. Profiling mRNA and microRNA expression are discussed in view of their applicability to class prediction, class discovery, and comparison, as well as outcome prediction, and special attention is paid to the recent advances in our understanding of the role of alternative RNA splicing in AML. In addition to microarray-based GEP approaches, over the last few years RNA sequencing based on next-generation sequencing technology is gaining wider recognition as an advanced tool for transcriptome profiling. Therefore, the advantages of RNA sequencing-based GEP and its current and potential implications in AML are discussed. Finally, we also highlight recent efforts to integrate already available and newly acquired omics data sets so that a more precise understanding of AML biology and clinical behavior can be achieved, which ultimately will contribute to further refine leukemia management.

Role of heme oxygenase-1 in postnatal differentiation of stem cells: a possible cross-talk with microRNAs

SIGNIFICANCE

Heme oxygenase-1 (HO-1) converts heme to biliverdin, carbon monoxide, and ferrous ions, but its cellular functions are far beyond heme metabolism. HO-1 via heme removal and degradation products acts as a cytoprotective, anti-inflammatory, immunomodulatory, and proangiogenic protein, regulating also a cell cycle. Additionally, HO-1 can translocate to nucleus and regulate transcription factors, so it can also act independently of enzymatic function.

RECENT ADVANCES

Recently, a body of evidence has emerged indicating a role for HO-1 in postnatal differentiation of stem and progenitor cells. Maturation of satellite cells, skeletal myoblasts, adipocytes, and osteoclasts is inhibited by HO-1, whereas neurogenic differentiation and formation of cardiomyocytes perhaps can be enhanced. Moreover, HO-1 influences a lineage commitment in pluripotent stem cells and maturation of hematopoietic cells. It may play a role in development of osteoblasts, but descriptions of its exact effects are inconsistent.

CRITICAL ISSUES

In this review we discuss a role of HO-1 in cell differentiation, and possible HO-1-dependent signal transduction pathways. Among the potential mediators, we focused on microRNA (miRNA). These small, noncoding RNAs are critical for cell differentiation. Recently we have found that HO-1 not only influences expression of specific miRNAs but also regulates miRNA processing enzymes.

FUTURE DIRECTIONS

It seems that interplay between HO-1 and miRNAs may be important in regulating fates of stem and progenitor cells and needs further intensive studies.

MicroRNA-155 as an inducer of apoptosis and cell differentiation in Acute Myeloid Leukaemia

Background

Acute myeloid leukaemia (AML) is characterised by the halt in maturation of myeloid progenitor cells, combined with uncontrolled proliferation and abnormal survival, leading to the accumulation of immature blasts. In many subtypes of AML the underlying causative genetic insults are not fully described. MicroRNAs are known to be dysregulated during oncogenesis. Overexpression of miR-155 is associated with some cancers, including haematological malignancies, and it has been postulated that miR-155 has an oncogenic role. This study investigated the effects of modulating miR-155 expression in human AML cells, and its mechanism of action.

Results

Analysis of miR-155 expression patterns in AML patients found that Fms-like tyrosine kinase 3 (FLT3)-wildtype AML has the same expression level as normal bone marrow, with increased expression restricted to AML with the FLT3-ITD mutation. Induction of apoptosis by cytarabine arabinoside or myelomonocytic differentiation by 1,23-dihydroxyvitaminD3 in FLT3-wildtype AML cells led to upregulated miR-155 expression. Knockdown of miR-155 by locked nucleic acid antisense oligonucleotides in the FLT3-wildtype AML cells conferred resistance to cytarabine arabinoside induced apoptosis and suppressed the ability of cells to differentiate.

Ectopic expression of miR-155 in FLT3-wildtype AML cells led to a significant gain of myelomonocytic markers (CD11b, CD14 and CD15), increase in apoptosis (AnnexinV binding), decrease in cell growth and clonogenic capacity.

In silico target prediction identified a number of putative miR-155 target genes, and the expression changes of key transcription regulators of myeloid differentiation and apoptosis (MEIS1, GF1, cMYC, JARID2, cJUN, FOS, CTNNB1 and TRIB2) were confirmed by PCR. Assessment of expression of apoptosis-related proteins demonstrated a marked increase in cleaved caspase-3 expression confirming activation of the apoptosis cascade.

Conclusions

This study provides evidence for an anti-leukaemic role for miR-155 in human FLT3-wildtype AML, by inducing cell apoptosis and myelomonocytic differentiation, which is in contrast to its previously hypothesized role as an oncogene. This highlights the complexity of gene regulation by microRNAs that may have tumour repressor or oncogenic effects depending on disease context or tissue type.

Role of genotype-based approach in the clinical management of adult acute myeloid leukemia with normal cytogenetics

Acute myeloid leukemia (AML) is the most common form of acute leukemia affecting adults. Although it is a complex disease driven by numerous genetic and epigenetic abnormalities, nearly 50% of patients exhibit a normal karyotype (CN-AML) with an intermediate cytogenetic risk. However, a widespread genomic analysis has recently shown the recurrence of genomic aberrations in this category (mutations of FLT3, CEBPA, NPM1, RUNX1, TET2, IDH1/2, DNMT3A, ASXL1, MLL and WT1) thus revealing its marked genomic heterogeneity. In this perspective, a global gene expression analysis of AML patients provides an independent prognostic marker to categorize each patient into clinic-pathologic subgroups based on its molecular genetic defects. Consistently such classification, taking into account the uniqueness of each AML patient, furnishes an individualized treatment approach leading a step closer to personalized medicine. Overall the genome-wide analysis of AML patients, by providing novel insights into biology of this tumor, furnishes accurate prognostic markers as well as useful tools for selecting the most appropriate treatment option. Moreover it provides novel therapeutic targets useful to enhance efficacy of the current anti-AML therapeutics. Here we describe the prognostic relevance of such new genetic data and discuss how this approach can be used to improve survival and treatment of AML patients.

NPM1 Gene Type A Mutation in Bulgarian Adults with Acute Myeloid Leukemia: A Single-Institution Study

Objective: Mutations of the nucleophosmin (NPM1) gene are considered as the most frequent acute myeloid leukemia (AML)-associated genetic lesion, reported with various incidences in different studies, and type A (NPM1-A) is the most frequent type. However, since most series in the literature report on the features of all patients regardless of the type of mutation, NPM1-A(+) cases have not been well characterized yet. Therefore, we evaluated the prevalence of NPM1-A in Bulgarian AML patients and searched for an association with clinical and laboratory features.

Materials and Methods: One hundred and four adults (51 men, 53 women) were included in the study. NPM1-A status was determined using allele-specific reverse-transcription polymerase chain reaction with co-amplification of NPM1-A and β-actin and real-time quantitative TaqMan-based polymerase chain reaction. Patients received conventional induction chemotherapy and were followed for 13.2±16.4 months.

Results: NPM1-A was detected in 26 (24.8%) patients. NPM1-A mutation was detected in all AML categories, including in one patient with RUNX1-RUNX1T1. There were no differences associated with the NPM1-A status with respect to age, sex, hemoglobin, platelet counts, percentage of bone marrow blasts, splenomegaly, complete remission rates, and overall survival. NPM1-A(+) patients, compared to NPM1-A(-) patients, were characterized by higher leukocyte counts [(75.4±81.9)x109/L vs. (42.5±65.9)x109/L; p=0.049], higher frequency of normal karyotype [14/18 (77.8%) vs. 26/62 (41.9%); p=0.014], higher frequency of FLT3-ITD [11/26 (42.3%) vs. 8/77 (10.4%); p=0.001], and lower incidence of CD34(+) [6/21 (28.8%) vs. 28/45 (62.2%); p=0.017]. Within the FLT3-ITD(-) group, the median overall survival of NPM1-A(-) patients was 14 months, while NPM1-A(+) patients did not reach the median (p=0.10).

Conclusion: The prevalence of NPM1-A mutation in adult Bulgarian AML patients was similar to that reported in other studies. NPM1-A(+) patients were characterized by higher leukocyte counts, higher frequency of normal karyotypes and FLT3-ITD, and lower incidence of CD34(+), supporting the idea that the specific features of type A mutations might contribute to the general clinical and laboratory profile of NPM1(+) AML patients.

Implications of the miR-10 family in chemotherapy response of NPM1-mutated AML

Nucleophosmin-mutated acute myeloid leukemia (NPM1mut-AML) patients have a high rate of complete remission (CR) to induction chemotherapy. However, the mechanisms responsible for such effects are unknown. Because miR-10 family members are expressed at high levels in NPM1mut-AML, we evaluated whether these microRNAs could predict chemotherapy response in AML. We found that high baseline miR-10 family expression in 54 untreated cytogenetically heterogeneous AML patients was associated with achieving CR. However, when we included NPM1 mutation status in the multivariable model, there was a significant interaction effect between miR-10a-5p expression and NPM1 mutation status. Similar results were observed when using a second cohort of 183 cytogenetically normal older (age ≥ 60 years) AML patients. Loss- and gain-of-function experiments using miR-10a-5p in cell lines and primary blasts did not demonstrate any effect in apoptosis or cell proliferation at baseline or after chemotherapy. These data support a bystander role for the miR-10 family in NPM1mut-AML.

microRNA therapies in cancer

MicroRNAs (miRNAs or miRs) are a family of small non-coding RNA species that have been implicated in the control of many fundamental cellular and physiological processes such as cellular differentiation, proliferation, apoptosis and stem cell maintenance. miRNAs regulate gene expression by the sequence-selective targeting of mRNAs, leading to translational repression or mRNA degradation. Some microRNAs have been categorized as “oncomiRs” as opposed to “tumor suppressor miRs” Modulating the miRNA activities may provide exciting opportunities for cancer therapy. This review highlights the latest discovery of miRNAs involved in carcinogenesis as well as the potential applications of miRNA regulations in cancer treatment. Several studies have demonstrated the feasibility of restoring tumor suppressive miRNAs and targeting oncogenic miRNAs for cancer therapy using in vivo model systems.

microRNA therapies in cancer

MicroRNAs (miRNAs or miRs) are a family of small non-coding RNA species that have been implicated in the control of many fundamental cellular and physiological processes such as cellular differentiation, proliferation, apoptosis and stem cell maintenance. miRNAs regulate gene expression by the sequence-selective targeting of mRNAs, leading to translational repression or mRNA degradation. Some microRNAs have been categorized as "oncomiRs" as opposed to "tumor suppressor miRs" Modulating the miRNA activities may provide exciting opportunities for cancer therapy. This review highlights the latest discovery of miRNAs involved in carcinogenesis as well as the potential applications of miRNA regulations in cancer treatment. Several studies have demonstrated the feasibility of restoring tumor suppressive miRNAs and targeting oncogenic miRNAs for cancer therapy using in vivo model systems.

Diverse roles of miR-29 in cancer (review)

microRNAs (miRNAs) are non-coding RNAs which have the capacity to regulate gene expression at the post-transcriptional level, and have emerging as key factors involved in cancer at all stages ranging from initiation to metastasis. In the present review, we summmarize the diverse roles of the microRNA-29 (miR-29) family in cancer. First, we present a concise introduction to the miR-29 family and the expression profile of miR-29 in various cancer types. We next highlight the upstream regulatory pathway of miR-29 and describe the relationship between miR-29 and cancer in detail. As a tumor suppressor, miR-29 restrains cancer progression by promoting tumor cell apoptosis, by suppressing DNA methylation of tumor-suppressor genes, by reducing proliferation of tumors and by increasing chemosensitivity. However, as a tumor promoter, miR-29 mediates epithelial-mesenchymal transition (EMT) and promotes metastasis in breast cancer and colon cancer. Finally, we suggest that miR-29 represents a novel diagnostic and prognostic biomarker or a therapeutic target for cancer. Our review highlights the diverse relationship between miR-29 and cancer (particularly digestive system neoplasms). Further research of miR-29 in cancer is warranted.

Hox gene dysregulation in acute myeloid leukemia

ABSTRACT: 

In humans, class I homeobox genes (HOX genes) are distributed in four clusters. Upstream regulators include transcriptional activators and members of the CDX family of transcription factors. HOX genes encode proteins and need cofactor interactions, to increase their specificity and selectivity. HOX genes contribute to the organization and regulation of hematopoiesis by controlling the balance between proliferation and differentiation. Changes in HOX gene expression can be associated with chromosomal rearrangements generating fusion genes, such as those involving MLL and NUP98, or molecular defects, such as mutations in NPM1 and CEBPA for example. Several miRNAs are involved in the control of HOX gene expression and their expression correlates with HOX gene dysregulation. HOX genes dysregulation is a dominant mechanism of leukemic transformation. A better knowledge of their target genes and the mechanisms by which their dysregulated expression contributes to leukemogenesis could lead to the development of new drugs.

TRPM3

Like most other members of the TRP family, the Trpm3 gene encodes proteins that form cation-permeable ion channels on the plasma membrane. However, TRPM3 proteins have several unique features that set them apart from the other members of this diverse family. The Trpm3 gene encodes for a surprisingly large number of isoforms generated mainly by alternative splicing. Only for two of the (at least) eight sites at which sequence diversity is generated the functional consequences have been elucidated, one leading to nonfunctional channels, the other one profoundly affecting the ionic selectivity. In the Trpm3 gene an intronic microRNA (miR-204) is co-transcribed with Trpm3. By regulating the expression of a multitude of genes, miR-204 increases the functional complexity of the Trpm3 locus. Over the past years, important progress has been made in discovering pharmacological tools to manipulate TRPM3 channel activity. These substances have facilitated the identification of endogenously expressed functional TRPM3 channels in nociceptive neurons, pancreatic beta cells, and vascular smooth muscle cells, among others. TRPM3 channels, which themselves are temperature sensitive, thus have been implicated in sensing noxious heat, in modulating insulin release, and in secretion of inflammatory cytokines. However, in many tissues where TRPM3 proteins are known to be expressed, no functional role has been identified for these channels so far. Because of the availability of adequate pharmacological and genetic tools, it is expected that future investigations on TRPM3 channels will unravel important new aspects and functions of these channels.

MicroRNA-10b promotes nucleus pulposus cell proliferation through RhoC-Akt pathway by targeting HOXD10 in intervetebral disc degeneration

Aberrant proliferation of nucleus pulposus cell is implicated in the pathogenesis of intervertebral disc degeneration. Recent findings revealed that microRNAs, a class of small noncoding RNAs, could regulate cell proliferation in many pathological conditions. Here, we showed that miR-10b was dramatically upregulated in degenerative nucleus pulposus tissues when compared with nucleus pulposus tissues isolated from patients with idiopathic scoliosis. Moreover, miR-10b levels were associated with disc degeneration grade and downregulation of HOXD10. In cultured nucleus pulposus cells, miR-10b overexpression stimulated cell proliferation with concomitant translational inhibition of HOXD10 whereas restored expression of HOXD10 reversed the mitogenic effect of miR-10b. MiR-10b-mediated downregulation of HOXD10 led to increased RhoC expression and Akt phosphorylation. Either knockdown of RhoC or inhibition of Akt abolished the effect of miR-10b on nucleus pulposus cell proliferation. Taken together, aberrant miR-10b upregulation in intervertebral disc degeneration could contribute to abnormal nucleus pulposus cell proliferation through derepressing the RhoC-Akt pathway by targeting HOXD10. Our study also underscores the potential of miR-10b and the RhoC-Akt pathway as novel therapeutic targets in intervertebral disc degeneration.

The Role of miRNA in Haematological Malignancy

Currently, there are over 1,800 annotated human miRNAs, many of which have tissue-specific expression. Numerous studies have highlighted their role in haematopoietic differentiation and proliferation, acting as master regulators of haematopoietic stem cell function. Aberrant expression of miRNAs has been observed in haematological cancers, exhibiting unique expression signatures in comparison to normal counterparts. Functional and target analyses as well as animal models have attempted to annotate how different miRNA may contribute to the pathophysiology of these malignancies from modulating cancer associated genes, functioning directly as oncogenes or tumour suppressor genes or acting as bystanders or regulators of the epigenetic mechanisms in cancer. miRNAs have also been shown to play a role in modulating drug resistance and determining prognosis between the various subtypes of blood cancers. This review discusses the important role that miRNAs play in haematological malignancies by exploring associations that exist between the two and trying to examine evidence of causality to support the tantalising possibility that miRNAs might serve as therapeutic targets in blood cancers.

A TrkB-STAT3-miR-204-5p regulatory circuitry controls proliferation and invasion of endometrial carcinoma cells

Background

We previously identified TrkB as an oncogene involved in promoting metastasis in endometrial carcinoma (EC). Here, we sought to delineate the effect of changes in TrkB expression on the global profile of microRNAs (miRNAs) in EC cells and further investigated the correlation between the expression of certain miRNA and TrkB in the clinicopathologic characteristics of EC patients.

Methods and results

Using quantitative reverse transcription-PCR (qRT-PCR), we found that expression of TrkB mRNA has no significant difference in transcript levels between normal endometrium and EC cells captured by laser capture microdissection, while immunohistochemistry results demonstrated a markedly higher expression of TrkB protein in EC tissues. The microRNA array showed that ectopic overexpression and knockdown of TrkB expression caused global changes in miRNA expression in EC cells. qRT-PCR results showed that elevated TrkB repressed miR-204-5p expression in EC cells. Furthermore, immunoblotting assays revealed that TrkB overexpression in Ishikawa^TrkB cells noticeably increased JAK2 and STAT3 phosphorylation, which, however, was aborted by TrkB knockdown in HEC-1B^shTrkB cells. Moreover, ChIP assays showed that phospho-STAT3 could directly bind to STAT3-binding sites near the TRPM3 promoter region upstream of miR-204-5p. Interestingly, using bioinformatics analysis and luciferase assays, we identified TrkB was a novel target of miR-204-5p. Functionally, the MTT assays, clonogenic and Transwell assays showed that miR-204-5p significantly suppressed the clonogenic growth, migration and invasion of EC cells. Furthermore, miR-204-5p also inhibited the growth of tumor xenografts bearing human EC cells. Importantly, we found lower miR-204-5p expression was associated with advanced FIGO stages, lymph node metastasis and probably a lower chance for survival in EC patients.

Conclusions

This study uncovers a new regulatory loop involving TrkB/miR-204-5p that is critical to the tumorigenesis of EC and proposes that reestablishment of miR-204-5p expression could be explored as a potential new therapeutic target for this disease.

A miRNA signature associated with human metastatic medullary thyroid carcinoma

MicroRNAs (miRNAs) represent a class of small, non-coding RNAs that control gene expression by targeting mRNA and triggering either translational repression or RNA degradation. The objective of our study was to evaluate the involvement of miRNAs in human medullary thyroid carcinoma (MTC) and to identify the markers of metastatic cells and aggressive tumour behaviour. Using matched primary and metastatic tumour samples, we identified a subset of miRNAs aberrantly regulated in metastatic MTC. Deregulated miRNAs were confirmed by quantitative real-time PCR and validated by in situ hybridisation on a large independent set of primary and metastatic MTC samples. Our results uncovered ten miRNAs that were significantly expressed and deregulated in metastatic tumours: miR-10a, miR-200b/-200c, miR-7 and miR-29c were down-regulated and miR-130a, miR-138, miR-193a-3p, miR-373 and miR-498 were up-regulated. Bioinformatic approaches revealed potential miRNA targets and signals involved in metastatic MTC pathways. Migration, proliferation and invasion assays were performed in cell lines treated with miR-200 antagomirs to ascertain a direct role for this miRNA in MTC tumourigenesis. We show that the members of miR-200 family regulate the expression of E-cadherin by directly targeting ZEB1 and ZEB2 mRNA and through the enhanced expression of tumour growth factor β (TGFβ)-2 and TGFβ-1. Overall, the treated cells shifted to a mesenchymal phenotype, thereby acquiring an aggressive phenotype with increased motility and invasion. Our data identify a robust miRNA signature associated with metastatic MTC and distinct biological processes, e.g., TGFβ signalling pathway, providing new potential insights into the mechanisms of MTC metastasis.

TGF-β-induced miR10a/b expression promotes human glioma cell migration by targeting PTEN

Human gliomas are associated with high rates of morbidity and mortality. In the brain, increased mRNA levels of transforming growth factor β (TGF-β) correlate with the degree of malignancy of human gliomas. miR10a/10b expression has been demonstrated to be associated with TGF-β expression in brain tumors, and it is reported that TGF-β induces miR10 expression. Therefore, miR10a/10b expression may be induced by TGF-β expression and may be involved in the TGF-β-induced migration of brain tumor cells. The present study examined the expression of TGF-β and miR10a/10b in the tissues of 10 patients with brain tumors using quantitative PCR (qPCR), and the correlation between TGF-β and miR10a or miR10b expression was analyzed. Additionally, U251 and SHG-44 cells were treated with TGF-β and the expression of miR10a/10b was examined. Further, cell migration was analyzed following transfection of U251 cells with miR10a/10b and the association between miR10a/10b and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was investigated. U251 cells were transfected with miR10a/10b inhibitors and a PTEN expression plasmid prior to TGF-β treatment and then cell migration was assessed. A significant correlation was identified between TGF-β and miR10a expression (r2=0.6936, P=0.007) and between TGF-β and miR10b expression (r2=0.5876, P=0.02) in the tissues of patients with brain tumors. The results also showed that TGF-β induces miR10a/10b expression and that TGF-β-induced miR10a/10b expression promotes cell migration through the suppression of PTEN. In conclusion, TGF-β-induced miR10a/10b promotes brain tumor migration. This study may provide a number of suggestions for the clinical treatment of brain tumors.

Overexpressed let-7a-3 is associated with poor outcome in acute myeloid leukemia

Dysregulation of microRNA let-7a-3 has been identified in several solid tumors and is associated with prognosis of patients. However, the pattern of let-7a-3 expression and the impact on prognosis has not yet been studied in acute myeloid leukemia (AML). The purpose of this study is to investigate the expression status of let-7a-3 and its clinical significance in AML patients using real-time quantitative PCR. Overexpression of let-7a-3 was identified in 25 of 102 (25%) de novo AML. There was no significant difference in age, blood parameters, FAB/WHO subtypes, karyotype risks and nine gene mutations (FLT3-ITD, NPM1, C-KIT, IDH1/IDH2, DNMT3A, C/EBPA and N/K-RAS) between patients with and without let-7a-3 overexpression (P>0.05). The patients with let-7a-3 overexpression had similar rates of complete remission (CR) as those without let-7a-3 overexpression (50% vs. 56%, P=0.693). Although the overall survival (OS) of AML patients with let-7a-3 overexpression (median 12 months,) was shorter than those without overexpression (median 25 months), the difference was not statistically significant (P=0.228). However, among those 51 obtained CR, patients with let-7a-3 overexpression had significantly shorter OS than those without let-7a-3 overexpression (P=0.029). The difference in relapse-free survival (RFS) was also significant between two groups (P=0.005). These findings suggest that let-7a-3 overexpression is a common event and is associated with poor clinical outcome in AML.

MicroRNA expression at diagnosis adds relevant prognostic information to molecular categorization in patients with intermediate-risk cytogenetic acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease, and optimal treatment varies according to cytogenetic risk factors and molecular markers. Several studies have demonstrated the prognostic importance of microRNAs (miRNAs) in AML. Here we report a potential association between miRNA expression and clinical outcome in 238 intermediate-risk cytogenetic AML (IR-AML) patients from 16 institutions in the CETLAM cooperative group. We first profiled 670 miRNAs in a subset of 85 IR-AML patients from a single institution and identified 10 outcome-related miRNAs. We then validated these 10 miRNAs by individual assays in the total cohort and confirmed the prognostic impact of 4 miRNAs. High levels of miR-196b and miR-644 were independently associated with shorter overall survival, and low levels of miR-135a and miR-409-3p with a higher risk of relapse. Interestingly, miR-135a and miR-409-3p maintained their independent prognostic value within the unfavorable molecular subcategory (wild-type NPM1 and CEBPA and/or FLT3-ITD), and miR-644 retained its value within the favorable molecular subcategory. miR-409-3p, miR-135a, miR-196b and mir-644 arose as prognostic markers for IR-AML, both overall and within specific molecular subgroups.

Acquired copy number alterations of miRNA genes in acute myeloid leukemia are uncommon

Altered microRNA (miRNA) expression is frequently observed in acute myelogenous leukemia (AML) and has been implicated in leukemic transformation. Whether somatic copy number alterations (CNAs) are a frequent cause of altered miRNA gene expression is largely unknown. Herein, we used comparative genomic hybridization with a custom high-resolution miRNA-centric array and/or whole-genome sequence data to identify somatic CNAs involving miRNA genes in 113 cases of AML, including 50 cases of de novo AML, 18 cases of relapsed AML, 15 cases of secondary AML following myelodysplastic syndrome, and 30 cases of therapy-related AML. We identified a total of 48 somatic miRNA gene-containing CNAs that were not identified by routine cytogenetics in 20 patients (18%). All these CNAs also included one or more protein coding genes. We identified a single case with a hemizygous deletion of MIR223, resulting in the complete loss of miR-223 expression. Three other cases of AML were identified with very low to absent miR-223 expression, an miRNA gene known to play a key role in myelopoiesis. However, in these cases, no somatic genetic alteration of MIR223 was identified, suggesting epigenetic silencing. These data show that somatic CNAs specifically targeting miRNA genes are uncommon in AML.

Genome-wide association study for biomarker identification of Rapamycin and Everolimus using a lymphoblastoid cell line system

The mammalian target of rapamycin (mTOR) inhibitors, a set of promising potential anti-cancer agents, has shown response variability among individuals. This study aimed to identify novel biomarkers and mechanisms that might influence the response to Rapamycin and Everolimus. Genome-wide association (GWA) analyses involving single nucleotide polymorphisms (SNPs), mRNA, and microRNAs microarray data were assessed for association with area under the cytotoxicity dose response curve (AUC) of two mTOR inhibitors in 272 human lymphoblastoid cell lines (LCLs). Integrated analysis among SNPs, expression data, microRNA data and AUC values were also performed to help select candidate genes for further functional characterization. Functional validation of candidate genes using siRNA screening in multiple cell lines followed by MTS assays for the two mTOR inhibitors were performed. We found that 16 expression probe sets (genes) that overlapped between the two drugs were associated with AUC values of two mTOR inhibitors. One hundred and twenty seven and one hundred SNPs had P < 10⁻⁴, while 8 and 10 SNPs had P < 10⁻⁵ with Rapamycin and Everolimus AUC, respectively. Functional studies indicated that 13 genes significantly altered cell sensitivity to either one or both drugs in at least one cell line. Additionally, one microRNA, miR-10a, was significantly associated with AUC values for both drugs and was shown to repress expression of genes that were associated with AUC and desensitize cells to both drugs. In summary, this study identified genes and a microRNA that might contribute to response to mTOR inhibitors.

miRNAs and long noncoding RNAs as biomarkers in human diseases

Noncoding RNAs (ncRNAs) are transcripts that have no apparent protein-coding capacity; however, many ncRNAs have been found to play a major biological role in human physiology. Their deregulation is implicated in many human diseases, but their exact roles are only beginning to be elucidated. Nevertheless, ncRNAs are extensively studied as a novel source of biomarkers, and the fact that they can be detected in body fluids makes them extremely suitable for this purpose. The authors mainly focus on ncRNAs as biomarkers in cancer, but also touch on other human diseases such as cardiovascular diseases, autoimmune diseases, neurological disorders and infectious diseases. The authors discuss the established methods and provide a selection of emerging new techniques that can be used to detect and quantify ncRNAs. Finally, the authors discuss ncRNAs as a new strategy for therapeutic interventions.

miR-128 and its target genes in tumorigenesis and metastasis

MicroRNAs (miRNAs) are a class of endogenous, non-coding, 18-24 nucleotide length single-strand RNAs that could modulate gene expression at post-transcriptional level. Previous studies have shown that miR-128 enriched in the brain plays an important role in the development of nervous system and the maintenance of normal physical functions. Aberrant expression of miR-128 has been detected in many types of human tumors and its validated target genes are involved in cancer-related biological processes such as cell proliferation, differentiation and apoptosis. In this review, we will summarize the roles of miR-128 and its target genes in tumorigenesis and metastasis.

Identification and analysis of the regulatory network of Myc and microRNAs from high-throughput experimental data

As a transcription factor, c-Myc exerts significant influence in cancer development by regulating transcription of a large number of target genes including microRNAs. However, details of regulatory networks composed of Myc, microRNAs, and microRNA target genes are still unclear. Here, at system level, we built a comprehensive Myc-regulated miRNAs (Myc-miRNAs) regulatory network through the integration of experimentally validated high-throughput data and computational predictions. Using miRNA genomic information with ChIP-PET, we identified 30 Myc-miRNAs and found most of these Myc-miRNAs target genes were significantly enriched in cell cycle, apoptosis, cell proliferation GO terms and Myc-regulated signaling pathways, using gene sets enrichment analysis. We found most Myc-miRNAs involved in Myc-related cancer pathways expressed abnormally in Myc-associated tumors through the integration of diverse types of experimental data. Based upon Myc target genes identified by ChIP-chip assays, we identified that 1031 Myc-miRNAs feed-forward loops (FFLs) were significantly different from those obtained by chance; also, 11 high-quality FFLs were extracted from experimentally validated interactions. Finally, we built the miRNA-protein interaction network of experimentally validated Myc-miRNAs and discussed the more complex network composed of several FFLs networks. As shown in this study, we performed comprehensive analysis of the Myc-miRNAs regulatory network and provided potential Myc-miRNAs target genes which were involved in Myc pathway and cancer-related biological processes.

microRNAs as potential regulators of myeloid-derived suppressor cell expansion

Proper development and activation of cells of the myeloid lineage are critical for supporting innate immunity. This myelopoiesis is orchestrated by interdependent interactions between cytokine receptors, transcription factors and, as recently described, microRNAs (miRNAs). miRNAs contribute to normal and dysregulated myelopoiesis. Alterations in myelopoiesis underlie myeloid-derived suppressor cell (MDSC) expansion, a poorly understood heterogeneous population of immature and suppressive myeloid cells that expand in nearly all diseases where inflammation exists. MDSCs associated with inflammation often have immunosuppressive properties, but molecular mechanisms responsible for MDSC expansion are unclear. Emerging data implicate miRNAs in MDSC expansion. This review focuses on miRNAs that contribute to myeloid lineage differentiation and maturation under physiological conditions, and introduces the concept that altered miRNA expression my underlie expansion and accumulation of MDSCs. We divide our miRNAs into those with potential to promote MDSC expansion and two with known direct links to MDSC expansion, miR-223 and miR-494.

Attenuation of dexamethasone-induced cell death in multiple myeloma is mediated by miR-125b expression

Dexamethasone is a key front-line chemotherapeutic for B-cell malignant multiple myeloma (MM). Dexamethasone modulates MM cell survival signaling but fails to induce marked cytotoxicity when used as a monotherapy. We demonstrate here the mechanism behind this insufficient responsiveness of MM cells toward dexamethasone, revealing in MM a dramatic anti-apoptotic role for microRNA (miRNA)-125b in the insensitivity toward dexamethasone-induced apoptosis. MM cells responding to dexamethasone exhibited enhanced expression of oncogenic miR-125b. Dexamethasone also induced expression of miR-34a, which acts to suppress SIRT1 deacetylase, and thus allows maintained acetylation and inactivation of p53. p53 mRNA is also suppressed by miR-125b targeting. Reporter assays showed that both these dexamethasone-induced miRNAs act downstream of their target genes to prevent p53 tumor suppressor actions and, ultimately, resist cytotoxic responses in MM. Use of antisense miR-125b transcripts enhanced expression of pro-apoptotic p53, repressed expression of anti-apoptotic SIRT1 and, importantly, significantly enhanced dexamethasone-induced cell death responses in MM. Pharmacological manipulations showed that the key regulation enabling complete dexamethasone sensitivity in MM cells lies with miR-125b. In summary, dexamethasone-induced miR-125b induces cell death resistance mechanisms in MM cells via the p53/miR-34a/SIRT1 signaling network and provides these cells with an enhanced level of resistance to cytotoxic chemotherapeutics. Clearly, such anti-apoptotic mechanisms will need to be overcome to more effectively treat nascent, refractory and relapsed MM patients. These mechanisms provide insight into the role of miRNA regulation of apoptosis and their promotion of MM cell proliferative mechanisms.

A single center analysis of nucleophosmin in acute myeloid leukemia: value of combining immunohistochemistry with molecular mutation analysis

Mutations of nucleophosmin 1 are frequently found in acute myeloid leukemia and lead to aberrant cytoplasmic accumulation of nucleophosmin protein. Immunohistochemical staining is therefore recommended as the technique of choice in front-line screening. In this study, we assessed the sensitivity and specificity of immunohistochemistry on formalin-fixed bone marrow biopsies compared with gold standard molecular analysis to predict nucleophosmin 1 mutation status in 119 patients with acute myeloid leukemia. Discrepant cases were further characterized by gene expression analyses and fluorescence in situ hybridization. A large overlap between both methods was observed. Nevertheless, nine patients demonstrated discordant results at initial screening. Five cases demonstrated nuclear staining of nucleophosmin 1 by immunohistochemistry, but a nucleophosmin 1 mutation by molecular analysis. In two cases this could be attributed to technical issues and in three cases minor subpopulations of myeloblasts had not been discovered initially. All tested cases exhibited the characteristic nucleophosmin-mutated gene expression pattern. Four cases had cytoplasmic nucleophosmin 1 staining and a nucleophosmin-mutated gene expression pattern without a detectable nucleophosmin 1 mutation. In two of these cases we found the chromosomal translocation t(3;5)(q25;q35) encoding the NPM-MLF1 fusion protein. In the other discrepant cases the aberrant cytoplasmic nucleophosmin staining and gene expression could not be explained. In total six patients (5%) had true discordant results between immunohistochemistry and mutation analysis. We conclude that cytoplasmic nucleophosmin localization is not always caused by a conventional nucleophosmin 1 mutation and that in the screening for nucleophosmin 1 abnormalities, most information will be obtained by combining immunohistochemistry with molecular analysis.

CD34 expression predicts an adverse outcome in patients with NPM1-positive acute myeloid leukemia

Patients with acute myeloid leukemia (AML) harboring an NPM1 mutation exhibit a heterogeneous clinical outcome. Recent studies have shown that the absence of FLT3 internal tandem duplication (FLT3-ITD) mutation confers a favorable prognosis in NPM1-positive AML. However, the prognostic impact of immunophenotypes in this subgroup remains unclear. In this study, FLT3 mutation status and immunophenotypic profile of 85 NPM1-positive patients with de novo AML were retrospectively analyzed and correlated with their clinical features and survival outcomes. Univariate analysis detected 5 markers with prognostic relevance: older age (≥60 years), high white blood cell (WBC) count (>30 × 10(9)/L), FLT3-ITD, CD7, and CD34 expression. Multivariate analysis showed that high WBC count was the only independent predictor of a lower complete remission rate (P = .019). Older age (P = .035), high WBC count (P = .008), FLT3-ITD (P = .012), and CD34 expression (P = .006) were independent predictors of a shorter event-free survival (EFS). High WBC count (P = .014), FLT3-ITD (P = .005), and CD34 expression (P = .047) were independent predictors of a shorter overall survival (OS). Furthermore, based on FLT3-ITD status in NPM1 mutation-positive patients, we showed that both high WBC and CD34 expression conferred a poor EFS (P = .010 and P = .016, respectively) and OS (P = .032 and P = .001, respectively) in the FLT3-ITD-negative group, whereas high WBC predicted a poor EFS (P = .016) and OS (P = .027) in the FLT3-ITD-positive group. Our results confirm the prognostic value of assessing FLT3-ITD mutations in NPM1-positive AML and identify the adverse prognostic impact of high WBC and CD34 expression in this subgroup of AML.

MicroRNAs in myeloid malignancies

MicroRNAs (miRNAs) are key to the pathogenesis of human malignancies and increasingly recognized as potential biomarkers and therapeutic targets. Haematological malignancies, being the earliest human malignancies linked to aberrant miRNA expression, have consistently underpinned our understanding of the role that miRNAs play in cancer development. Here, we review the expanding roles attributed to miRNAs in the pathogenesis of different types of myeloid malignancies and highlight key findings.

Molecular prognostic factors in cytogenetically normal acute myeloid leukemia

Chromosomal abnormalities are detected in 50-60% of patients with acute myeloid leukemia (AML) and are important predictors of prognosis and risk of relapse. The remaining patients, those with cytogenetically normal AML, are a seemingly homogeneous group that in fact consists of subsets of patients with distinct clinical outcomes. This heterogeneity is likely related to acquired gene mutations, as well as altered miRNA and gene-expression profiles, which occur within the group. The identification of recurrent molecular abnormalities has improved prognostication and provided insight into mechanisms of leukemogenesis for patients with cytogenetically normal AML, as well as led to the discovery of novel therapeutic targets. As the number of mutations continues to expand, bioinformatic algorithms that allow for integration of multiple markers will be necessary to provide optimal care for patients with this disease.

The human NPM1 mutation A perturbs megakaryopoiesis in a conditional mouse model

The NPM1 mutant affects megakaryocytic development in mice. NPMc+ mutant mice mimic some features of human NPM1-mutated AML.

MicroRNAs in hematological malignancies

MicroRNAs (miRNAs) have become one of the hottest topics in biology over recent years, but remarkably have only been formally recognized for just over 10 years. These endogenously produced short (19-24 nt) non-coding RNAs have introduced an entirely new paradigm in our understanding of gene control and it is now evident that miRNAs play a crucial regulatory role in many, if not all, physiological and pathological processes. In this review we provide an overview of the role and potential clinical utility for miRNAs in hematological malignancies and their function in normal hematopoiesis. Although still in its infancy, the miRNA field has already added much to our understanding of hematological processes, and provides us with novel tools as both biomarkers and therapeutic agents for hematological malignancies.

miR-150 blocks MLL-AF9-associated leukemia through oncogene repression

The microRNA miR-150, a critical regulator of hematopoiesis, is downregulated in mixed-lineage leukemia (MLL). In this study, miR-150 acts as a potent leukemic tumor suppressor by blocking the oncogenic properties of leukemic cells. By using MLL-AF9-transformed cells, we demonstrate that ectopic expression of miR-150 inhibits blast colony formation, cell growth, and increases apoptosis in vitro. More importantly, ectopic expression of miR-150 in MLL-AF9-transformed cells completely blocked the development of myeloid leukemia in transplanted mice. Furthermore, gene expression profiling revealed that miR-150 altered the expression levels of more than 30 "stem cell signature" genes and many others that are involved in critical cancer pathways. In addition to the known miR-150 target Myb, we also identified Cbl and Egr2 as bona fide targets and shRNA-mediated suppression of these genes recapitulated the pro-apoptotic effects observed in leukemic cells with miR-150 ectopic expression. In conclusion, we demonstrate that miR-150 is a potent leukemic tumor suppressor that regulates multiple oncogenes.

IMPLICATIONS

These data establish new, key players for the development of therapeutic strategies to treat MLL-AF9-related leukemia.

Therapeutic Delivery of MicroRNA-29b by Cationic Lipoplexes for Lung Cancer

MicroRNA-29b (miR-29b) expression has been shown to be reduced in non-small-cell lung cancer (NSCLC) tissues. Here, we have identified the oncogene cyclin-dependent protein kinase 6 (CDK6) as a direct target of miR-29b in lung cancer. We hypothesized that in vivo restoration of miR-29b and thus targeting of genes important to tumor initiation and progression may represent an option for lung cancer treatment. We developed a cationic lipoplexes (LPs)-based carrier that efficiently delivered miR-29b both in vitro and in vivo. LPs containing miR-29b (LP-miR-29b) efficiently delivered miR-29b to NSCLC A549 cells, reduced the expression of key targets CDK6, DNMT3B, and myeloid cell leukemia sequence 1 (MCL1), as well as cell growth and clonogenicity of A549 cells. In addition, the IC50 for cisplatin in the miR-29b-treated cells was effectively reduced. In a xenograft murine model, LPs efficiently accumulated at tumor sites. Systemic delivery of LP-miR-29b increased the tumor miR-29b expression by approximately fivefold, downregulated the tumor mRNA expression of CDK6, DNMT3B, and MCL1 by ~57.4, ~40.5, and ~52.4%, respectively, and significantly inhibited tumor growth by ~60% compared with LP-miR-NC (negative control). Our results demonstrate that cationic LPs represent an efficient delivery system that holds great potential in the development of miRNA-based therapeutics for lung cancer treatment.Molecular Therapy-Nucleic Acids (2013) 2, e84; doi:10.1038/mtna.2013.14; published online 16 April 2013.

The Role of MicroRNAs in Hematopoietic Stem Cell and Leukemic Stem Cell Function

Hematopoietic stem cells (HSCs) are defined by their ability to self-renew and reconstitute all elements of the hematopoietic system. Acute myeloid leukemia (AML) is thought to arise from, and be maintained by, leukemic stem cells (LSCs), which exhibit similar features to HSCs, including the abilities to self-renew and differentiate into non-self-renewing cells. Acquisition of stem-cell-like characteristics by the LSCs is likely mediated in part by molecular mechanisms that normally regulate HSC function. Thus, understanding the shared and unique aspects of the molecular regulation of these cell populations will be important to understanding the relationship between normal hematopoiesis and leukemogenesis. MicroRNAs (miRNAs) are small noncoding RNAs that act at the posttranscriptional level to regulate protein expression. Unfortunately, most investigations of the role of miRNAs in normal hematopoiesis have been restricted to studies of their effects on lineage commitment in progenitors and mature effector cell function, but not on HSCs. Recent studies have identified miRNAs that enhance HSC function, and an abundance of profiling studies using primary AML samples have identified dysregulated miRNAs that may target genes implicated in self-renewal (HOX genes, P53, and PTEN), thus providing a potential link between normal and malignant stem cells. While these studies as well as recent in vivo models of miRNA-induced leukemogenesis (e.g. miR-29a, miR-125b) suggest a role for miRNAs in the development of AML, future studies using serial transplantation of primary AML blasts, from both mouse models and primary human AML specimens, will be necessary to assess the roles of miRNAs in LSC biology.

FOXC1 in human trabecular meshwork cells is involved in regulatory pathway that includes miR-204, MEIS2, and ITGβ1

Forkhead box C1 (FOXC1) is a transcription factor that affects eye development. FOXC1 is implicated in the etiology of glaucoma because mutations in the gene are among the causes of Axenfeld-Rieger syndrome which is often accompanied by glaucoma. Glaucoma is the second leading cause of blindness. It is a complex disorder whose genetic basis in most patients remains unknown. Microarrays expression analysis was performed to identify genes in human trabecular meshwork (TM) primary cultures that are affected by FOXC1 and genes that may have roles in glaucoma. This represents the first genome wide analysis of FOXC1 target genes in any tissue. FOXC1 knock down by siRNAs affected the expression of 849 genes. Results on selected genes were confirmed by real time PCR, immunoblotting, and dual luciferase reporter assays. Observation of MEIS2 as a FOXC1 target and consideration of FOXC1 as a potential target of miR-204 prompted testing the effect of this micro RNA on expression of FOXC1 and several genes identified by array analysis as FOXC1 target genes. It was observed that miR-204 caused decreased expression of FOXC1 and the FOXC1 target genes CLOCK, PLEKHG5, ITGβ1, and MEIS2 in the TM cultures. Expression of CLOCK, PLEKHG5, ITGβ1 has not previously been reported to be affected by miR-204. The data suggest existence of a complex regulatory pathway in the TM part of which includes interactions between FOXC1, miR-204, MEIS2, and ITGβ1. All these molecules are known to have TM relevant functions, and the TM is strongly implicated in the etiology of glaucoma.

Nucleophosmin mutations in acute myeloid leukemia: a tale of protein unfolding and mislocalization

Nucleophosmin (NPM1) is an abundant, ubiquitously expressed protein mainly localized at nucleoli but continuously shuttling between nucleus and cytoplasm. NPM1 plays a role in several cellular functions, including ribosome biogenesis and export, centrosome duplication, chromatin remodeling, DNA repair, and response to stress stimuli. Much of the interest in this protein arises from its relevance in human malignancies. NPM1 is frequently overexpressed in solid tumors and is the target of several chromosomal translocations in hematologic neoplasms. Notably, NPM1 has been characterized as the most frequently mutated gene in acute myeloid leukemia (AML). Mutations alter the C-terminal DNA-binding domain of the protein and result in its aberrant nuclear export and stable cytosolic localization. In this review, we focus on the leukemia-associated NPM1 C-terminal domain and describe its structure, function, and the effect exerted by leukemic mutations. Finally, we discuss the possibility to target NPM1 for the treatment of cancer and, in particular, of AML patients with mutated NPM1 gene.

Silvestrol exhibits significant in vivo and in vitro antileukemic activities and inhibits FLT3 and miR-155 expressions in acute myeloid leukemia

Background

Activating mutations [internal tandem duplication (ITD)] or overexpression of the FMS-like tyrosine kinase receptor-3 (FLT3) gene are associated with poor outcome in acute myeloid leukemia (AML) patients, underscoring the need for novel therapeutic approaches. The natural product silvestrol has potent antitumor activity in several malignancies, but its therapeutic impact on distinct molecular high-risk AML subsets remains to be fully investigated. We examined here the preclinical activity of silvestrol in FLT3-ITD and FLT3 wild-type (wt) AML.

Methods

Silvestrol in vitro anti-leukemic activity was examined by colorimetric cell viability assay, colony-forming and flow cytometry assays assessing growth inhibition and apoptosis, respectively. Pharmacological activity of silvestrol on FLT3 mRNA translation, mRNA and protein expression was determined by RNA-immunoprecipitation, qRT-PCR and immunoblot analyses, respectively. Silvestrol in vivo efficacy was investigated using MV4-11 leukemia-engrafted mice.

Results

Silvestrol shows antileukemia activity at nanomolar concentrations both in FLT3-wt overexpressing (THP-1) and FLT3-ITD (MV4-11) expressing AML cell lines (IC₅₀ = 3.8 and 2.7 nM, respectively) and patients’ primary blasts [IC₅₀ = ~12 nM (FLT3-wt) and ~5 nM (FLT3-ITD)]. Silvestrol increased apoptosis (~4fold, P = 0.0001), and inhibited colony-formation (100%, P < 0.0001) in primary blasts. Silvestrol efficiently inhibited FLT3 translation reducing FLT3 protein expression by 80–90% and decreased miR-155 levels (~60%), a frequently co-regulated onco-miR in FLT3-ITD-positive AML. The median survival of silvestrol-treated vs vehicle-treated mice was 63 vs 29 days post-engraftment, respectively (P < 0.0001).

Conclusions

Silvestrol exhibits significant in vivo and in vitro antileukemic activities in AML through a novel mechanism resulting in inhibition of FLT3 and miR-155 expression. These encouraging results warrant a rapid translation of silvestrol for clinical testing in AML.