The prognostic and functional role of microRNAs in acute myeloid leukemia. Blood. 2011;117:1121-1129. [PMID: 21045193 DOI: 10.1182/blood-2010-09-191312]

Identification and analysis of methylation signature genes and association with immune infiltration in pediatric acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a common leukemia with low cure rate and poor prognosis among pediatric patients. The regulation of AML immune microenvironment and methylation remains to be explored. Pediatric and adult AML patients differ significantly in epigenetic factors, and the efficiency of treatment modalities varies between the two groups of patients.

METHODS

We collected mRNA, miRNA and DNA methylation data from pediatric AML patients across multiple databases. Differentially expression genes were identified, and a gene-miRNA regulatory network was constructed. Prognostic risk models were established by integrating LASSO and Cox regression, and a nomogram was generated. Based on this model, we investigated tumor-infiltrating immune cells and cell communication, analyzing the biological functions and pathways associated with prognostic factors. Furthermore, the relationships between all prognostic factors and gene modules were explored, and the impact of these factors on treatment modalities was determined.

RESULTS

We developed an efficient prognostic risk model and identified HOXA9, SORT1, SH3BP5, mir-224 and mir-335 as biomarkers. We validated these findings in an external dataset and observed a correlation between age and risk in pediatric patients. AML samples with lower risk scores have a better prognosis and higher expression of immune-upregulated biomarkers, and have lower immune scores. Furthermore, we detected discrepancies in immune cell infiltration and interactions between high- and low-risk group samples, which affected the efficacy of immunotherapy. We evaluated all prognostic factors and predicted the effect of immunotherapy and medicine.

CONCLUSION

This study comprehensively investigated the role of methylation signature genes in pediatric AML at the level of genomes and transcriptomes. The research aims to enhance the risk stratification, prognosis evaluation and assessment of treatment effectiveness of AML patients. This study also highlight the uniqueness of pediatric AML and foster the development of new immunotherapy and targeted therapy strategies.

MicroRNA mediated gene regulatory circuits leads to machine learning based preliminary detection of Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) can be detected based on morphology, cytochemistry, immunological markers, and cytogenetics. MicroRNAs (miRNAs) influence key biological pathways in multiple haematological malignancies including AML. In this work, we have analysed the miRNome and the transcriptome of normal and AML samples and have identified the significant set of miRNA-target mRNA pairs present within AML- Peripheral Blood and AML- Bone Marrow samples from both tissue and cell lines. The miRNA target genes are further filtered based on their functional significance in AML system. These filtered genes constitute the set of selected miRNA target features, which have been finally used for developing machine learning based prediction tool, 'TbAMLPred' for preliminary detection of AML. This model implements both unsupervised clustering and supervised classification algorithms that would increase the reliability of prediction. Our results show that the selected miRNA target-based features can separate the control and disease samples linearly. Overall, we put forward 'TbAMLPred' for a non-invasive mode of preliminary AML diagnosis in future. Github link for accessing TbAMLPred: https://github.com/zglabDIB/TbAMLPred.

Human circulating small non-coding RNA signature as a non-invasive biomarker in clinical diagnosis of acute myeloid leukaemia

Background: Acute myeloid leukaemia (AML) is the most common acute leukaemia in adults; AML is highly heterogeneous and involves abnormalities at multiple omics levels. Small non-coding RNAs (sncRNAs) present in body fluids are important regulatory molecules and considered promising non-invasive clinical diagnostic biomarkers for disease. However, the signature of sncRNA profile alteration in AML patient serum and bone marrow supernatant is still under exploration. Methods: We examined data for blood and bone marrow samples from 80 consecutive, newly-diagnosed patients with AML and 12 healthy controls for high throughput small RNA-sequencing. Differentially expressed sncRNAs were analysed to reveal distinct patterns between AML patients and controls. Machine learning methods were used to evaluate the efficiency of specific sncRNAs in discriminating individuals with AML from controls. The altered expression level of individual sncRNAs was evaluated by RT-PCR, Q-PCR, and northern blot. Correlation analysis was employed to assess sncRNA patterns between serum and bone marrow supernatant. Results: We identified over 20 types of sncRNA categories beyond miRNAs in both serum and bone marrow supernatant, with highly coordinated expression patterns between them. Non-classical sncRNAs, including rsRNA (62.86%), ysRNA (14.97%), and tsRNA (4.22%), dominated among serum sncRNAs and showed sensitive alteration patterns in AML patients. According to machine learning-based algorithms, the tsRNA-based signature robustly discriminated subjects with AML from controls and was more reliable than that comprising miRNAs. Our data also showed that serum tsRNAs to be closely associated with AML prognosis, suggesting the potential application of serum tsRNAs as biomarkers to assist in AML diagnosis. Conclusions: We comprehensively characterized the expression pattern of circulating sncRNAs in blood and bone marrow and their alteration signature between healthy controls and AML patients. This study enriches research of sncRNAs in the regulation of AML, and provides insights into the role of sncRNAs in AML.

CircNFIX knockdown inhibited AML tumorigenicity by the miR-876-3p/TRIM31 axis

BACKGROUND

Acute myeloid leukemia (AML) is one of the most common malignant myeloid diseases in adults with a dismal prognosis. We aimed to explore the effects of circNFIX on the proliferation and apoptosis of AML cells.

METHODS

The expressions of circNFIX, miR-876-3p and tripartite motif (TRIM) 31 in the bone marrow specimens of AML patients and AML cell lines were detected by qRT-PCR or western blot. Cell proliferation was evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5-ethynyl-29-deoxyuridine (EdU) assays. Cell cycle and apoptosis were analyzed by flow cytometry. Western blot was used to detect protein expression. The relationship between miR-876-3p and circNFIX or TRIM31 was identified by dual-luciferase reporter assay or RNA pull-down assay.

RESULTS

The expression level of circNFIX was significantly increased in the bone marrow samples of AML patients and AML cells when compared with normal controls. CircNFIX silencing inhibited AML cell proliferation and promoted apoptosis. Inhibition of miR-876-3p reversed the effect of circNFIX knockdown on AML cell progression. In addition, circNFIX indirectly regulated TRIM31 through miR-876-3p. Further, TRIM31 overexpression counteracted the effect of circNFIX silencing on AML cell proliferation and apoptosis.

CONCLUSION

CircNFIX knockdown could suppress the proliferation and induce the apoptosis of AML cells by targeting the miR-876-3p/TRIM31 axis.

miR-196b-TLR7/8 Signaling Axis Regulates Innate Immune Signaling and Myeloid Maturation in DNMT3A-Mutant AML

PURPOSE

DNMT3A mutations confer a poor prognosis in acute myeloid leukemia (AML), but the molecular mechanisms downstream of DNMT3A mutations in disease pathogenesis are not completely understood, limiting targeted therapeutic options. The role of miRNA in DNMT3A-mutant AML pathogenesis is understudied.

EXPERIMENTAL DESIGN

DNA methylation and miRNA expression was evaluated in human AML patient samples and in Dnmt3a/Flt3-mutant AML mice. The treatment efficacy and molecular mechanisms of TLR7/8-directed therapies on DNMT3A-mutant AML were evaluated in vitro on human AML patient samples and in Dnmt3a/Flt3-mutant AML mice.

RESULTS

miR-196b is hypomethylated and overexpressed in DNMT3A-mutant AML and is associated with poor patient outcome. miR-196b overexpression in DNMT3A-mutant AML is important to maintain an immature state and leukemic cell survival through repression of TLR signaling. The TLR7/8 agonist resiquimod induces dendritic cell-like differentiation with costimulatory molecule expression in DNMT3A-mutant AML cells and provides a survival benefit to Dnmt3a/Flt3-mutant AML mice. The small molecule bryostatin-1 augments resiquimod-mediated AML growth inhibition and differentiation.

CONCLUSIONS

DNMT3A loss-of-function mutations cause miRNA locus-specific hypomethylation and overexpression important for mutant DNMT3A-mediated pathogenesis and clinical outcomes. Specifically, the overexpression of miR-196b in DNMT3A-mutant AML creates a novel therapeutic vulnerability by controlling sensitivity to TLR7/8-directed therapies.

Acute Myeloid Leukemia: New Multiomics Molecular Signatures and Implications for Systems Medicine Diagnostics and Therapeutics Innovation

Acute myeloid leukemia (AML) is a common, complex, and multifactorial malignancy of the hematopoietic system. AML diagnosis and treatment outcomes display marked heterogeneity and patient-to-patient variations. To date, AML-related biomarker discovery research has employed single omics inquiries. Multiomics analyses that reconcile and integrate the data streams from multiple levels of the cellular hierarchy, from genes to proteins to metabolites, offer much promise for innovation in AML diagnostics and therapeutics. We report, in this study, a systems medicine and multiomics approach to integrate the AML transcriptome data and reporter biomolecules at the RNA, protein, and metabolite levels using genome-scale biological networks. We utilized two independent transcriptome datasets (GSE5122, GSE8970) in the Gene Expression Omnibus database. We identified new multiomics molecular signatures of relevance to AML: miRNAs (e.g., mir-484 and miR-519d-3p), receptors (ACVR1 and PTPRG), transcription factors (PRDM14 and GATA3), and metabolites (in particular, amino acid derivatives). The differential expression profiles of all reporter biomolecules were crossvalidated in independent RNA-Seq and miRNA-Seq datasets. Notably, we found that PTPRG holds important prognostication potential as evaluated by Kaplan-Meier survival analyses. The multiomics relationships unraveled in this analysis point toward the genomic pathogenesis of AML. These multiomics molecular leads warrant further research and development as potential diagnostic and therapeutic targets.

Acute myeloid leukemia cell-derived extracellular vesicles carrying microRNA-548ac regulate hematopoietic function via the TRIM28/STAT3 pathway

microRNAs (miRNAs or miRs) can be delivered from acute myeloid leukemia (AML) cells to hematopoietic stem cells (HSCs) to regulate hematopoietic function via extracellular vesicles (EVs). In this study, we investigated the roles played by EVs that transport miR-548ac from AML cells in normal hematopoiesis. Bioinformatics analysis demonstrated that miR-548ac was highly expressed in AML-derived EVs. The expression of miR-548ac and TRIM28 and the targeting relationship were identified, and the results demonstrated that the expression of miR-548ac was upregulated in AML cell lines and AML cell-secreted EVs compared with CD34⁺ HSCs. AML-derived EVs targeted CD34⁺ HSCs to induce decreased expression of TRIM28 and downstream activation of STAT3. Exosomal miR-548ac was transferred into CD34⁺ HSCs to target TRIM28. Through gain- and loss-of-function assays, it was observed that the abrogated expression of miR-548ac or STAT3 promoted colony-forming units (CFU), whereas overexpressed miR-548ac repressed CFU, which was rescued by overexpression of TRIM28. Taken together, these results indicated that miR-548ac delivered by AML cell-derived EVs inhibits hematopoiesis via TRIM28-dependent STAT3 activation.

MiRNA-301b-3p induces proliferation and inhibits apoptosis in AML cells by targeting FOXF2 and regulating Wnt/β-catenin axis

BACKGROUND

MiRNA-301b-3p functions as an oncomiRNA or tumor suppressor, and has been reported in various cancer types, including pancreatic, colorectal, oral, hepatocellular and lung cancers. Although the expression of miRNA-301b-3p is upregulated in acute myeloid leukemia (AML), its biological function and precise mechanisms remain unclarified. This study explores the roles of miRNA-301b-3p in AML, with the aim of ascertaining its regulatory action on Wnt/β-catenin axis by targeting Forkhead box F2 (FOXF2).

METHODS

The expression levels of miRNA-301b-3p and FOXF2 were measured by quantitative real-time PCR. The effects of miRNA-301b-3p knockdown and overexpression on cell proliferation were evaluated by CCK8 and cell counting assays, while cell apoptosis was analyzed by flow cytometry. The expression levels of apoptosis-related proteins, including FOXF2, and other targets in Wnt/β-catenin axis were determined by immunoblotting. Possible interaction between miRNA-301-3p and FOXF2 in AML cells was examined by luciferase reporter assays.

RESULTS

MiRNA-301b-3p was dramatically upregulated in AML cells, and showed a negative correlation with FOXF2 expression. Downregulation of miRNA-301b-3p suppressed proliferation and promoted apoptosis in AML cells. MiRNA-301b targeted FOXF2 to regulate Wnt/β-catenin axis. In the rescue experiments, FOXF2 overexpression partly reversed the effect of miRNA-301b-3p mimic in AML cells.

CONCLUSION

The current findings demonstrate that miRNA-301b-3p targets FOXF2 to induce proliferation and inhibit apoptosis in AML cells via regulation of Wnt/β-catenin axis.

Prognostic impact of PRDM16 expression in acute myeloid leukemia with normal cytogenetics

PURPOSE

Cytogenetically normal acute myeloid leukemia (CN-AML) is a heterogeneous disease with variable clinical outcomes. The identification of potential biomarkers to better classify the patients with unfavorable prognoses who may require more aggressive therapies is an emergent demand. PRDM16 is a transcriptional cofactor and histone methyltransferase, playing a critical role in maintaining hematopoietic stem cells, and MLL fusion-induced leukemogenesis. However, the prognostic value of PRDM16 in CN-AML is still unclear.

MATERIALS AND METHODS

We retrospectively analyzed the PRDM16 expression and its association with gene mutations in CN-AML. Then the prognostic value of PRDM16 and its comparison with WT1 were analyzed.

RESULTS

The results showed that about 73.6% of CN-AML patients harbored higher expression of PRDM16 than the healthy controls. Furthermore, CN-AML patients with high PRDM16 expression had a lower survival rate than the low PRDM16 expression group (50.5% vs. 83.3%, p = 0.0339). Interestingly, hemopoietic stem cell transplantation significantly improved the prognosis of CN-AML with high PRDM16 expression but not those with low PRDM16 expression. In terms of molecular genetics, high PRDM16 expression was significantly associated with a lower rate of CEBPA mutation (p = 0.01) and a higher rate of FLT3-ITD and DNMT3A mutation (p = 0.032 and p = 0.004, respectively). In addition, PRDM16 expression was significantly correlated with WT1 expression in CN-AML (r = 0.7, p < 0.001). These data suggested PRDM16 expression could be used to predict the outcome of patients with CN-AML.

CONCLUSION

PRDM16 is significantly associated with FLT3-ITD and DNMT3A mutation and WT1 expression and serves as a potential prognostic biomarker in CN-AML.

Dysregulated Expression of MiR-19b, MiR-25, MiR-17, WT1, and CEBPA in Patients with Acute Myeloid Leukemia and Association with Graft versus Host Disease after Hematopoietic Stem Cell Transplantation

Elham JamaliObjectives  Acute myeloid leukemia (AML) is a blood malignancy characterized by the proliferation of aberrant cells in the bone marrow and blood that interfere with normal blood cells. We have investigated whether changes in the level of micro-ribonucleic acid (miR)-19b, miR-17, and miR-25, Wilms' tumor (WT1), and CCAAT enhancer-binding protein α (CEBPA) genes expression affect disease prognosis and clinical outcome in AML patients. Materials and Methods  The expression level of miR-19-b, miR-17, and miR-25, as well as WT1 and CEBPA genes in a group of patients and controls as well as different risk groups (high, intermediate, and favorite risk), M3 versus non-M3, and graft-versus-host disease (GvHD) versus non-GvHD patients were assessed using a quantitative SYBR Green real-time polymerase chain reaction method. Results  When compared with the baseline level at the period of diagnosis before chemotherapy, the expression of miR-19b and miR-17 in AML patients increased significantly after chemotherapy. The level of miR-19b and miR-25 expression in AML patients with M3 and non-M3 French-American-British subgroups differ significantly. MiR-19b and miR-25 expression was elevated in GvHD patients, while miR-19b and miR-25 expression was somewhat decreased in GvHD patients compared with non-GvHD patients, albeit the difference was not statistically significant. Also, patients with different cytogenetic aberrations had similar levels of miR-19-b and miR-25 expression. Conclusion  MiR-19b, miR-17, and miR-25 are aberrantly expressed in AML patients' peripheral blood leukocytes, which may play a role in the development of acute GvHD following hematopoietic stem cell transplantation.

Role of Biomarkers in FLT3 AML

Simple Summary

Genetically heterogeneous disorder acute myeloid leukemia (AML) is marked by recurring mutations in FLT3. Current FLT3 inhibitors and other emerging inhibitors have helped in the improvement of the quality of standard of care therapies; however, the overall survival of the patients remains static. This is due to numerous mutations in FLT3, which causes resistance against these FLT3 inhibitors. For effective treatment of AML patients, alternative approaches are required to overcome this resistance. Here, we will summarize the biomarkers for FLT3 inhibitors in AML, as well as the alternative measures to overcome resistance to the current therapies.

Abstract

Acute myeloid leukemia is a disease characterized by uncontrolled proliferation of clonal myeloid blast cells that are incapable of maturation to leukocytes. AML is the most common leukemia in adults and remains a highly fatal disease with a five-year survival rate of 24%. More than 50% of AML patients have mutations in the FLT3 gene, rendering FLT3 an attractive target for small-molecule inhibition. Currently, there are several FLT3 inhibitors in the clinic, and others remain in clinical trials. However, these inhibitors face challenges due to lack of efficacy against several FLT3 mutants. Therefore, the identification of biomarkers is vital to stratify AML patients and target AML patient population with a particular FLT3 mutation. Additionally, there is an unmet need to identify alternative approaches to combat the resistance to FLT3 inhibitors. Here, we summarize the current knowledge on the utilization of diagnostic, prognostic, predictive, and pharmacodynamic biomarkers for FLT3-mutated AML. The resistance mechanisms to various FLT3 inhibitors and alternative approaches to combat this resistance are also discussed and presented.

The Role of miRNA in Regulating the Fate of Monocytes in Health and Cancer

Monocytes represent a heterogeneous population of blood cells that provide a link between innate and adaptive immunity. The unique potential of monocytes as both precursors (e.g., of macrophages) and effector cells (as phagocytes or cytotoxic cells) makes them an interesting research and therapeutic target. At the site of a tumor, monocytes/macrophages constitute a major population of infiltrating leukocytes and, depending on the type of tumor, may play a dual role as either a bad or good indicator for cancer recovery. The functional activity of monocytes and macrophages derived from them is tightly regulated at the transcriptional and post-transcriptional level. This review summarizes the current understanding of the role of small regulatory miRNA in monocyte formation, maturation and function in health and cancer development. Additionally, signatures of miRNA-based monocyte subsets and the influence of exogenous miRNA generated in the tumor environment on the function of monocytes are discussed.

Microenvironment and drug resistance in acute myeloid leukemia: Do we know enough?

Acute myeloid leukemia (AMLs), as the name suggests, often develop suddenly and are very progressive forms of cancer. Unlike in acute promyelocytic leukemia, a subtype of AML, the outcomes in most other AMLs remain poor. This is mainly attributed to the acquired drug resistance and lack of targeted therapy. Different studies across laboratories suggest that the cellular mechanisms to impart therapy resistance are often very dynamic and should be identified in a context-specific manner. Our review highlights the progress made so far in identifying the different cellular mechanisms of mutation-independent therapy resistance in AML. It reiterates that for more effective outcomes cancer therapies should acquire a more tailored approach where the protective interactions between the cancer cells and their niches are identified and targeted.

miRNAs in the Regulation of Cancer Immune Response: Effect of miRNAs on Cancer Immunotherapy

In the last few decades, carcinogenesis has been extensively explored and substantial research has identified immunogenic involvement in various types of cancers. As a result, immune checkpoint blockers and other immune-based therapies were developed as novel immunotherapeutic strategies. However, despite being a promising therapeutic option, immunotherapy has significant constraints such as a high cost of treatment, unpredictable toxicity, and clinical outcomes. miRNAs are non-coding, small RNAs actively involved in modulating the immune system's multiple signalling pathways by binding to the 3'-UTR of target genes. miRNAs possess a unique advantage in modulating multiple targets of either the same or different signalling pathways. Therefore, miRNA follows a 'one drug multiple target' hypothesis. Attempts are made to explore the therapeutic promise of miRNAs in cancer so that it can be transported from bench to bedside for successful immunotherapeutic results. Therefore, in the current manuscript, we discussed, in detail, the mechanism and role of miRNAs in different types of cancers relating to the immune system, its diagnostic and therapeutic aspect, the effect on immune escape, immune-checkpoint molecules, and the tumour microenvironment. We have also discussed the existing limitations, clinical success and the prospective use of miRNAs in cancer.

MicroRNAs and JAK/STAT3 signaling: A new promising therapeutic axis in blood cancers

Blood disorders include a wide spectrum of blood-associated malignancies resulting from inherited or acquired defects. The ineffectiveness of existing therapies against blood disorders arises from different reasons, one of which is drug resistance, so different types of leukemia may show different responses to treatment. Leukemia occurs for a variety of genetic and acquired reasons, leading to uncontrolled proliferation in one or more cell lines. Regarding the genetic defects, oncogene signal transducer and activator of transcription (STAT) family transcription factor, especially STAT3, play an essential role in hematological disorders onset and progress upon mutations, dysfunction, or hyperactivity. Besides, microRNAs, as biological molecules, has been shown to play a dual role in either tumorigenesis and tumor suppression in various cancers. Besides, a strong association between STAT3 and miRNA has been reported. For example, miRNAs can regulate STAT3 via targeting its upstream mediators such as IL6, IL9, and JAKs or directly binding to the STAT3 gene. On the other hand, STAT3 can regulate miRNAs. In this review study, we aimed to determine the role of either microRNAs and STAT3 along with their effect on one another's activity and function in hematological malignancies.

Association between diabetes and acute lymphocytic leukemia, acute myeloid leukemia, non-Hopkin lymphoma, and multiple myeloma

Objective

Diabetes increases the risk for cancers. However, whether it is associated with hematologic malignancies is not clear. The present study investigated the association between diabetes and acute lymphocytic leukemia (ALL), acute myeloid leukemia (ML), non-Hopkin lymphoma (NHL), and multiple myeloma (MM).

Methods

Newly diagnosed adult cancer patients were recruited consecutively from our clinical database. Peoples from a local enterprise were recruited to create a small-scale population-based dataset. We compared the diabetes prevalence between the cancer patients and the local people; an increase in diabetes prevalence in the cancer patients suggests an association between diabetes and the cancer(s).

Results

We found that the prevalence of diabetes was 19.7%, 21.3%, 12.5%, and 12.0% in ALL, AML, NHL, and MM, respectively, which was higher than that (9.1%) in the local people. Despite that there were more male than female cancer patients, there were more female than male diabetic patients. The increase in diabetes prevalence occurred in ALL and NHL patients aged 18 to 39 years old as well as in AML patients over 40. In MM patients, the increase in diabetes prevalence (18.6%) occurred only in females. Approximately 70% of the diabetic patients were undiagnosed before the diagnosis of the blood cancer. Approximately half of the pre-existing diabetic patients had anti-diabetic treatment, with over 70% of them still had poor glycemic control.

Conclusions

Our results suggest that diabetes is associated with ALL, AML, NHL, and MM, at least in adult patients.

Aberrantly reduced expression of miR-342-5p contributes to CCND1-associated chronic myeloid leukemia progression and imatinib resistance

Chronic myeloid leukemia (CML) is a myeloproliferative disorder associated with the Philadelphia chromosome, and the current standard of care is the use of tyrosine kinase inhibitors (TKI). However, some patients will not achieve a molecular response and may progress to blast crisis, and the underlying mechanisms remain to be clarified. In this study, next-generation sequencing was used to explore endogenous miRNAs in CML patients versus healthy volunteers, and miR-342-5p was identified as the primary target. We found that miR-342-5p was downregulated in CML patients and had a significant inhibitory effect on cell proliferation in CML. Through a luciferase reporter system, miR-342-5p was reported to target the 3'-UTR domain of CCND1 and downregulated its expression. Furthermore, overexpression of miR-342-5p enhanced imatinib-induced DNA double-strand breaks and apoptosis. Finally, by analyzing clinical databases, we further confirmed that miR-342-5p was associated with predicted molecular responses in CML patients. In conclusion, we found that both in vivo and in vitro experiments and database cohorts showed that miR-342-5p plays a key role in CML patients, indicating that miR-342-5p may be a potential target for future CML treatment or prognostic evaluation.

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.

Construction of a microRNA-mRNA Regulatory Network in De Novo Cytogenetically Normal Acute Myeloid Leukemia Patients

Background: The association between dysregulated microRNAs (miRNAs) and acute myeloid leukemia (AML) is well known. However, our understanding of the regulatory role of miRNAs in the cytogenetically normal AML (CN-AML) subtype pathway is still poor. The current study integrated miRNA and mRNA profiles to explore novel miRNA-mRNA interactions that affect the regulatory patterns of de novo CN-AML. Methods: We utilized a multiplexed nanoString nCounter platform to profile both miRNAs and mRNAs using similar sets of patient samples (n = 24). Correlations were assessed, and an miRNA-mRNA network was constructed. The underlying biological functions of the mRNAs were predicted by gene enrichment. Finally, the interacting pairs were assessed using TargetScan and microT-CDS. We identified 637 significant negative correlations (false discovery rate <0.05). Results: Network analysis revealed a cluster of 12 miRNAs representing the majority of mRNA targets. Within the cluster, five miRNAs (miR-495-3p, miR-185-5p, let-7i-5p, miR-409-3p, and miR-127-3p) were posited to play a pivotal role in the regulation of CN-AML, as they are associated with the negative regulation of myeloid leukocyte differentiation, negative regulation of myeloid cell differentiation, and positive regulation of hematopoiesis. Conclusion: Three novel interactions in CN-AML were predicted as let-7i-5p:HOXA9, miR-495-3p:PIK3R1, and miR-495-3p:CDK6 may be responsible for regulating myeloid cell differentiation in CN-AML.

MiR-15a-5p Confers Chemoresistance in Acute Myeloid Leukemia by Inhibiting Autophagy Induced by Daunorubicin

Anthracyclines remain a cornerstone of induction chemotherapy for acute myeloid leukemia (AML). Refractory or relapsed disease due to chemotherapy resistance is a major obstacle in AML management. MicroRNAs (miRNAs) have been observed to be involved in chemoresistance. We previously observed that miR-15a-5p was overexpressed in a subgroup of chemoresistant cytogenetically normal AML patients compared with chemosensitive patients treated with daunorubicin and cytarabine. MiR-15a-5p overexpression in AML cells reduced apoptosis induced by both drugs in vitro. This study aimed to elucidate the mechanisms by which miR-15a-5p contributes to daunorubicin resistance. We showed that daunorubicin induced autophagy in myeloid cell lines. The inhibition of autophagy reduced cell sensitivity to daunorubicin. The overexpression of miR-15a-5p decreased daunorubicin-induced autophagy. Conversely, the downregulation of miR-15a-5p increased daunorubicin-induced autophagy. We found that miR-15a-5p targeted four genes involved in autophagy, namely ATG9a, ATG14, GABARAPL1 and SMPD1. Daunorubicin increased the expression of these four genes, and miR-15a-5p counteracted this regulation. Inhibition experiments with the four target genes showed the functional effect of miR-15a-5p on autophagy. In summary, our results indicated that miR-15a-5p induces chemoresistance in AML cells through the abrogation of daunorubicin-induced autophagy, suggesting that miR-15a-5p could be a promising therapeutic target for chemoresistant AML patients.

MiR-17 and miR-93 Promote Tumor Progression by Targeting p21 in Patients with Chordoma

Objective

MicroRNAs have been implicated in the progression of various cancers. However, the role of microRNAs in chordoma remains to be further elucidated. Here, we purposed to character the role of two microRNAs, miR-17 and miR-93, and their potential mechanisms in chordoma.

Methods

The expression and prognostic value of miR-17 and miR-93 were assessed by the quantitative real-time polymerase chain reaction, Kaplan-Meier survival curve, and Cox regression analysis. The effects of miR-17/93 mimics on chordoma cell proliferation, colony formation, and invasion were analyzed by CCK-8 assay, colony formation assay, and transwell assay. The downstream target of miR-17/93 was further explored via luciferase reporter assay.

Results

High expression of miR-17/93 was identified in chordoma tissues, and was associated with poor prognosis. Overexpression of miR-17/93 contributed to cell proliferation, colony formation, and invasion. Mechanistically, we demonstrated that miR-17/93 directly targeted p21 and decreased the expression of p21. Besides, the rescue assay further confirmed the essential role of the miR-17/93-p21 axis in chordoma.

Conclusion

Our results revealed the potential oncogenic effect of the miR-17/93 on chordoma progression, and suggested that the miR-17/93-p21 axis served as a promising therapeutic target in chordoma.

Comparison of miRNA expressions among benign, premalignant and malignant lesions of the larynx: could they be transformation biomarkers?

Background

The malignancy potential of the laryngeal lesions are one of the major concerns of the surgeons about choosing the treatment options, forming surgical margins, deciding the follow-up periods. Finding a biomarker to overcome these concerns are ongoing challenges and recently microRNAs (miRNAs) are attributed as possible candidates since they can regulate gene expressions in the human genome. The objective of our study was to investigate their capability as a transformation biomarker for malignant laryngeal lesions.

Materials and methods

We investigated mature miRNA expressions in paraffin-embedded surgical specimens of human laryngeal tissues grouped as benign, premalignant or malignant (n = 10 in each). miRNA profiling was carried out by quantitative Real-Time polymerase chain reaction (RT-qPCR) and data were analyzed according to fold regulation.

Results

Our results demonstrated that 9 miRNAs were upregulated as the lesions become more malignant. Among them Hs_miR-183_5p, Hs_miR-155_5p, and Hs_miR-106b_3p expressions were significantly 4.16 (p = 0.032), 2.72 (p = 0.028) and 3.01 (p = 0.022) fold upregulated respectively in premalignant lesions compared to the benign lesions. Moreover, their expressions were approximately 2.76 fold higher in the malignant group than in the premalignant group compared to the benign group. Besides them, significant 7.57 (p = 0.036), 4.45 (p = 0.045) and 5.98 (p = 0.023) fold upregulations of Hs_miR-21_5p, Hs_miR-218_3p, and Hs_miR-210_3p were noticed in the malignant group but not in the premalignant group when compared to the benign group, respectively.

Conclusion

MiRNAs might have important value to help the clinicians for their concerns about the malignancy potentials of the laryngeal lesions. Hs_miR-183_5p, Hs_miR-155_5p, and Hs_miR-106b_3p might be followed as transformation marker, whereas Hs_miR-21_5p, Hs_miR-218_3p, and Hs_miR-210_3p might be a biomarker prone to malignancy.

MicroRNAs Associated With a Good Prognosis of Acute Myeloid Leukemia and Their Effect on Macrophage Polarization

Acute myeloid leukemia (AML) is an aggressive myeloid malignancy with poor outcomes despite very intensive therapeutic approaches. For the majority of patients which are unfit and treated less intensively, the prognosis is even worse. There has been unspectacular progress in outcome improvement over the last decades and the development of new approaches is of tremendous interest. The tumor microenvironment is credited with an important role in supporting cancer growth, including leukemogenesis. Macrophages are part of the tumor microenvironment and their contribution in this setting is increasingly being deciphered, these cells being credited with a tumor supporting role. Data on macrophage role and polarization in leukemia is scarce. MicroRNAs (miRNAs) have a role in the post-transcriptional regulation of gene expression, by impending translation and promoting degradation of messenger RNAs. They are important modulators of cellular pathways, playing major roles in normal hematopoietic differentiation. miRNA expression is significantly correlated with the prognosis of hematopoietic malignancies, including AML. Oncogenic miRNAs correlate with poor prognosis, while tumor suppressor miRNAs, which inhibit the expression of proto-oncogenes, are correlated with a favorable prognosis. miRNAs are proposed as biomarkers for diagnosis and prognosis and are regarded as therapeutic approaches in many cancers, including AML. miRNAs with epigenetic or modulatory activity, as well as with synergistic activity with chemotherapeutic agents, proved to be promising therapeutic targets in experimental, pre-clinical approaches. The clinical availability of emerging compounds with mimicking or suppressor activity provides the opportunity for future therapeutic targeting of miRNAs. The present paper is focusing on miRNAs which, according to current knowledge, favorably impact on AML outcomes, being regarded as tumor suppressors, and reviews their role in macrophage polarization. We are focusing on miRNA expression in the setting of AML, but data on correlations between miRNA expression and macrophage polarization is mostly coming from studies involving normal tissue.

MicroRNA-107 promotes apoptosis of acute myelocytic leukemia cells by targeting RAD51

INTRODUCTION

This study aimed to investigate the role of microRNA (miRNA) that affects acute myelocytic leukemia (AML) and its potential molecular mechanism by constructing a miRNA-mRNA interaction network using bioinformatics methods.

MATERIAL AND METHODS

MicroRNA expression data of AML were retrieved from Gene Expression Omnibus (GEO) and analyzed by microarray analysis. Expression levels of miR-107 and RAD51 mRNA were detected by quantitative real time polymerase chain reaction (qRT-PCR). Protein expression of RAD51, pro-apoptotic protein Bax, apoptosis related protein CytC and anti-apoptotic protein Bcl-2 were determined by Western blot. The rate of cell apoptosis was detected by Annexin-V/PI. The predicted targeting relationship between miR-107 and the 3'UTR of RAD51 was first predicted by the online application TargetScan and then verified by dual-luciferase assay.

RESULTS

Acute myelocytic leukemia-associated genes (n = 197) and miRNAs (n = 1701) were retrieved from the database, the interaction network of miRNA-mRNA was constructed and the core position was occupied by RAD51. miR-107 exhibited a regulatory effect on RAD51 in which the mRNA and protein expression of RAD51 were both significantly inhibited by miR-107 mimics in vitro. Additionally, down-regulated expression of miR107 as well as up-regulated expression of RAD51 were detected not only in the plasma of AML patients compared to healthy volunteers, but also in AML cell lines compared to the normal bone marrow stromal cell line. Further study found that increased expression of miR-107 and the consequent down-regulation of RAD51 could aggravate the apoptosis of AML cells in vitro.

CONCLUSIONS

Our present results showed that the crucial role of RAD51 and miR-107 in the apoptosis of AML cells, i.e., miR-107 promotes the apoptosis of AML cells through down-regulating the expression of RAD51.

The shape of gene expression distributions matter: how incorporating distribution shape improves the interpretation of cancer transcriptomic data

BACKGROUND

In genomics, we often assume that continuous data, such as gene expression, follow a specific kind of distribution. However we rarely stop to question the validity of this assumption, or consider how broadly applicable it may be to all genes that are in the transcriptome. Our study investigated the prevalence of a range of gene expression distributions in three different tumor types from the Cancer Genome Atlas (TCGA).

RESULTS

Surprisingly, the expression of less than 50% of all genes was Normally-distributed, with other distributions including Gamma, Bimodal, Cauchy, and Lognormal also represented. Most of the distribution categories contained genes that were significantly enriched for unique biological processes. Different assumptions based on the shape of the expression profile were used to identify genes that could discriminate between patients with good versus poor survival. The prognostic marker genes that were identified when the shape of the distribution was accounted for reflected functional insights into cancer biology that were not observed when standard assumptions were applied. We showed that when multiple types of distributions were permitted, i.e. the shape of the expression profile was used, the statistical classifiers had greater predictive accuracy for determining the prognosis of a patient versus those that assumed only one type of gene expression distribution.

CONCLUSIONS

Our results highlight the value of studying a gene's distribution shape to model heterogeneity of transcriptomic data and the impact on using analyses that permit more than one type of gene expression distribution. These insights would have been overlooked when using standard approaches that assume all genes follow the same type of distribution in a patient cohort.

miR-15a-5p and miR-21-5p contribute to chemoresistance in cytogenetically normal acute myeloid leukaemia by targeting PDCD4, ARL2 and BTG2

Cytarabine and daunorubicin are old drugs commonly used in the treatment of acute myeloid leukaemia (AML). Refractory or relapsed disease because of chemotherapy resistance is a major issue. microRNAs (miRNAs) were incriminated in resistance. This study aimed to identify miRNAs involved in chemoresistance in AML patients and to define their target genes. We focused on cytogenetically normal AML patients with wild‐type NPM1 without FLT3‐ITD as the treatment of this subset of patients with intermediate‐risk cytogenetics is not well established. We analysed baseline AML samples by small RNA sequencing and compared the profile of chemoresistant to chemosensitive AML patients. Among the miRNAs significantly overexpressed in chemoresistant patients, we revealed miR‐15a‐5p and miR‐21‐5p as miRNAs with a major role in chemoresistance in AML. We showed that miR‐15a‐5p and miR‐21‐5p overexpression decreased apoptosis induced by cytarabine and/or daunorubicin. PDCD4, ARL2 and BTG2 genes were found to be targeted by miR‐15a‐5p, as well as PDCD4 and BTG2 by miR‐21‐5p. Inhibition experiments of the three target genes reproduced the functional effect of both miRNAs on chemosensitivity. Our study demonstrates that miR‐15a‐5p and miR‐21‐5p are overexpressed in a subgroup of chemoresistant AML patients. Both miRNAs induce chemoresistance by targeting three pro‐apoptotic genes PDCD4, ARL2 and BTG2.

MicroRNA-143 sensitizes acute myeloid leukemia cells to cytarabine via targeting ATG7- and ATG2B-dependent autophagy

Targeting autophagy holds promise to enhance chemosensitivity in acute myeloid leukemia (AML). MicroRNA-143 (miR-143) has been found to suppress autophagy, however, it is not clear whether miR-143 augments cytarabine cytotoxicity in AML. Here, we report that cytarabine treatment reduces miR-143 expression in AML cell lines and primary AML cells. Moreover, ectopic expression of miR-143 further decreases cell viability in cytarabine-treated AML cells. By contrast, miR-143 knockdown inhibits cytarabine-induced cytotoxicity, together indicating a role of miR-143 in enhancing cytarabine sensitivity in AML. Subsequently, we show that miR-143 inhibits autophagy in cytarabine-treated AML cells by directly targeting autophagy-related proteins (ATG), ATG7 and ATG2B, two critical known components of autophagic machinery. More importantly, autophagy reconstructed via co-expression of ATG7 and ATG2B substantially attenuates miR-143-enhanced cytotoxicity, which is associated with suppression of caspase-dependent apoptotic pathway. Overall, this study demonstrates that targeting ATG7 and ATG2B-dependent autophagy is a critical mechanism by which miR-143 sensitizes AML to cytarabine, implicating it as a potential therapeutic target in AML treatment.

Identification of Acute Myeloid Leukemia Bone Marrow Circulating MicroRNAs

BACKGROUND

In addition to their roles in different biological processes, microRNAs in the tumor microenvironment appear to be potential diagnostic and prognostic biomarkers for various malignant diseases, including acute myeloid leukemia (AML). To date, no screening of circulating miRNAs has been carried out in the bone marrow compartment of AML. Accordingly, we investigated the circulating miRNA profile in AML bone marrow at diagnosis (AMLD) and first complete remission post treatment (AMLPT) in comparison to healthy donors (HD).

METHODS

Circulating miRNAs were isolated from AML bone marrow aspirations, and a low-density TaqMan miRNA array was performed to identify deregulated miRNAs followed by quantitative RT-PCR to validate the results. Bioinformatic analysis was conducted to evaluate the diagnostic and prognostic accuracy of the highly and significantly identified deregulated miRNA(s) as potential candidate biomarker(s).

RESULTS

We found several deregulated miRNAs between the AMLD vs. HD vs. AMLPT groups, which were involved in tumor progression and immune suppression pathways. We also identified significant diagnostic and prognostic signatures with the ability to predict AML patient treatment response.

CONCLUSIONS

This study provides a possible role of enriched circulating bone marrow miRNAs in the initiation and progression of AML and highlights new markers for prognosis and treatment monitoring.

Survival differences and associated molecular signatures of DNMT3A-mutant acute myeloid leukemia patients

Acute myeloid leukemia (AML) is a very heterogeneous and highly malignant blood cancer. Mutations of the DNA methyltransferase DNMT3A are among the most frequent recurrent genetic lesions in AML. The majority of DNMT3A-mutant AML patients shows fast relapse and poor survival, but also patients with long survival or long-term remission have been reported. Underlying molecular signatures and mechanisms that contribute to these survival differences are only poorly understood and have not been studied in detail so far. We applied hierarchical clustering to somatic gene mutation profiles of 51 DNMT3A-mutant patients from The Cancer Genome Atlas (TCGA) AML cohort revealing two robust patient subgroups with profound differences in survival. We further determined molecular signatures that distinguish both subgroups. Our results suggest that FLT3 and/or NPM1 mutations contribute to survival differences of DNMT3A-mutant patients. We observed an upregulation of genes of the p53, VEGF and DNA replication pathway and a downregulation of genes of the PI3K-Akt pathway in short- compared to long-lived patients. We identified that the majority of measured miRNAs was downregulated in the short-lived group and we found differentially expressed microRNAs between both subgroups that have not been reported for AML so far (miR-153-2, miR-3065, miR-95, miR-6718) suggesting that miRNAs could be important for prognosis. In addition, we learned gene regulatory networks to predict potential major regulators and found several genes and miRNAs with known roles in AML pathogenesis, but also interesting novel candidates involved in the regulation of hematopoiesis, cell cycle, cell differentiation, and immunity that may contribute to the observed survival differences of both subgroups and could therefore be important for prognosis. Moreover, the characteristic gene mutation and expression signatures that distinguished short- from long-lived patients were also predictive for independent DNMT3A-mutant AML patients from other cohorts and could also contribute to further improve the European LeukemiaNet (ELN) prognostic scoring system. Our study represents the first in-depth computational approach to identify molecular factors associated with survival differences of DNMT3A-mutant AML patients and could trigger additional studies to develop robust molecular markers for a better stratification of AML patients with DNMT3A mutations.

MicroRNA-126 attenuates cell apoptosis by targeting TRAF7 in acute myeloid leukemia cells

Acute myeloid leukemia (AML) has a 5-year survival rate of only about 30%-40% due to the self-renewal and differentiation ability of leukemia stem-like cells (LSCs). To address the potential for novel therapeutic targets in LSCs, we investigated the roles of miRNA-126 and tumor necrosis factor receptor-associated factor 7 (TRAF7) in AML. We used qRT-PCR and Western blot to investigate the expression levels of miRNA-126 and TRAF7 in AML cell lines. Then, we uncovered the effect of miRNA-126 on AML cell proliferation and apoptosis by MTT assay and flow cytometric analysis, respectively. Furthermore, dual-luciferase assay and Western blot were used to determine the target of miRNA-126 in AML and the potential mechanism by which cell apoptosis is suppressed by miRNA-126. We found that miRNA-126 was highly expressed in all of the AML cell lines, and that inhibition of miRNA-126 significantly induced cell death through apoptosis. The suppression of apoptosis in AML with high expression of miRNA-126 was caused by down-regulating TRAF7, which blocked the c-FLIP pathway. The role of miRNA-126 in AML makes it a potential therapeutic target to improve clinical outcomes for patients with AML.

MicroRNA-181a-3p as a Diagnostic and Prognostic Biomarker for Acute Myeloid Leukemia

Background

Micro (mi) RNAs play an important role in the pathogenesis and development of acute myeloid leukemia (AML), and their abnormal expression may be sufficient to predict the prognosis and outcomes in AML patients. We evaluated the clinical diagnostic value of miRNA-181a-3p in predicting prognosis and outcomes in patients with AML.

Methods

A total of 119 newly diagnosed adult patients with AML and 60 healthy controls were recruited. Blood specimens were obtained from all AML patients at diagnosis, and 10 blood specimens were obtained on day 28 after induction chemotherapy. The controls also provided blood samples. Relative gene expression was quantified by PCR and determined using the comparative Ct method. Publicly available clinical data and gene expressions for 188 patients with AML were downloaded from TCGA data portal.

Results

Compared with healthy controls, the expression of miRNA-181a-3p was significantly increased in patients with AML. MiR-181a-3p expression could be used to discriminate AML patients from controls, with up-regulated expression correlating with favorable prognosis. Moreover, miRNA-181a-3p expression was significantly decreased in patients who achieved a complete response after induction chemotherapy. The multivariate Cox analysis highlighted the prognostic value of miR-181a-3p for patients with AML. Finally, we found that miR-181a-3p expression was negatively correlated with the expression of the NF-κB essential modulator (NEMO/IKBKG).

Conclusions

MiR-181a-3p may be clinically useful as a disease marker for AML, and enhanced the prediction of patient outcomes to chemotherapy.

LncRNA TUG1 Regulates Cell Viability and Death by Regulating miR-193a-5p/Rab10 Axis in Acute Myeloid Leukemia

Background

Acute myeloid leukemia (AML) is a serious threat to human health. Long non-coding RNA (lncRNA) Taurine-Upregulated Gene1 (TUG1) has been reported to participate in the development and progression of several cancers, including AML. Herein, we aimed to investigate the pathognomonic role of TUG1 in AML cells and its potential mechanistic pathway.

Methods

Quantitative real-time PCR (qRT-PCR) assay was applied to detect the expression levels of lncRNA TUG1, miR-193a-5p and Rab10 in AML bone marrow and cell lines. The CCK-8 assay was conducted to assess the cell viability of AML HL-60 and NB4 cells and cell apoptotic assay was performed to assess the cell death. Dual-luciferase reporter assay was carried out to clarify the relationships among TUG1, miR-193a-5p and Rab10. Also, the protein level of Rab10 was examined by Western blot assay.

Results

LncRNA TUG1 was up-regulated in AML bone marrow and cells. Functional analysis showed that the silencing of TUG1 suppressed cell viability, while promoted cell death in AML HL-60 and NB4 cells. TUG1 targeted miR-193a-5p and negatively regulated miR-193a-5p expression. Overexpressed miR-193a-5p resulted in the decrease of cell viability and the increase in the cell death in AML cells. Restoration experiments proved that TUG1 regulated the cell viability and death of AML cells through regulating the miR-193a-5p/Rab10 axis. Rab10 was a direct target of miR-193a-5p and was inversely regulated by miR-193a-5p. TUG1 regulated the cell viability and death of AML cells through upregulating Rab10.

Conclusion

Silencing of lncRNA TUG1 induces a cytotoxic effect on AML cell lines through sponging miR-193a-5p and the suppression of Rab10.

miR-99 regulates normal and malignant hematopoietic stem cell self-renewal

The mechanisms that regulate self-renewal in hematopoietic stem cells (HSCs) and leukemia stem cells (LSCs) are poorly understood. Herein, Khalaj et al. identify microRNA-99 (miR-99) as a novel noncoding RNA critical for the maintenance of HSCs and LSCs and demonstrate that miR-99 mediates its role by suppressing multiple target genes, including HOXA1.

The microRNA-99 (miR-99) family comprises a group of broadly conserved microRNAs that are highly expressed in hematopoietic stem cells (HSCs) and acute myeloid leukemia stem cells (LSCs) compared with their differentiated progeny. Herein, we show that miR-99 regulates self-renewal in both HSCs and LSCs. miR-99 maintains HSC long-term reconstitution activity by inhibiting differentiation and cell cycle entry. Moreover, miR-99 inhibition induced LSC differentiation and depletion in an MLL-AF9–driven mouse model of AML, leading to reduction in leukemia-initiating activity and improved survival in secondary transplants. Confirming miR-99’s role in established AML, miR-99 inhibition induced primary AML patient blasts to undergo differentiation. A forward genetic shRNA library screen revealed Hoxa1 as a critical mediator of miR-99 function in HSC maintenance, and this observation was independently confirmed in both HSCs and LSCs. Together, these studies demonstrate the importance of noncoding RNAs in the regulation of HSC and LSC function and identify miR-99 as a critical regulator of stem cell self-renewal.

MicroRNAs: pivotal regulators in acute myeloid leukemia

MicroRNAs are a class of small non-coding RNAs that are 19-22 nucleotides in length and regulate a variety of biological processes at the post-transcriptional level. MicroRNA dysregulation disrupts normal biological processes, resulting in tumorigenesis. Acute myeloid leukemia is an invasive hematological malignancy characterized by the abnormal proliferation and differentiation of immature myeloid cells. Due to the low 5-year survival rate, there is an urgent need to discover novel diagnostic markers and therapeutic targets. In recent years, microRNAs have been shown to play important roles in hematological malignancies by acting as tumor suppressors and oncogenes. MicroRNAs have the potential to be a breakthrough in the diagnosis and treatment of acute myeloid leukemia. In this review, we summarize the biology of microRNAs and discuss the relationships between microRNA dysregulation and acute myeloid leukemia in the following aspects: signaling pathways, the abnormal biological behavior of acute myeloid leukemia cells, the clinical application of microRNAs and competing endogenous RNA regulatory networks.

MicroRNA-33b regulates sensitivity to daunorubicin in acute myelocytic leukemia by regulating eukaryotic translation initiation factor 5A-2

In this study, we aimed to study the effect of miR-33b in regulating sensitivity to daunorubicin (DNR) in acute myelocytic leukemia (AML). We used quantitative real-time polymerase chain reaction and Cell Counting Kit-8 assay to detect the level of miR-33b and cell viability. Cell apoptosis and the expression of eIF5A-2 and MCL-1 protein were detected by flow cytometry analysis and Western Blot analysis, respectively. MiR-33b mimic increased sensitivity of AML cells against DNR, while miR-33b inhibitor had the opposite effect. Furthermore, the results showed that the eIF5A-2 gene was a direct target of miR-33b, and miR-33b regulated eIF5A-2 mRNA and protein expression. Silencing of eIF5A-2 by RNA interference increased the sensitivity of AML cells against DNR. We also found that MCL-1 contributed to the regulation of DNR sensitivity, which was dependent on downregulation of eIF5A-2. Finally, knockdown of eIF5A-2 eliminated the effects of miRNA-33b mimic or inhibitor on DNR sensitivity. These findings indicate that miR-33b maybe as a new therapeutic target in AML cells.

A Long Non-coding RNA Lnc712 Regulates Breast Cancer Cell Proliferation

Great quantity of intergenic noncoding RNAs (lncRNAs) have been identified in the mammalian genome and involved in various biological processes, especially in the development and metastasis of cancer. In this study, we identified one lncRNA, lncRNA NONHSAT028712 (Lnc712), was highly expressed in breast cancer cell lines and tissues based on microarray screening. Knockdown of Lnc712 largely inhibited breast cancer cell proliferation. Mechanistically, Lnc712 bound specifically to heat-shock protein 90 (HSP90). Interaction between Lnc712 and HSP90 is required for HSP90 binding to cell division cycle 37 (Cdc37). The Lnc712/HSP90/Cdc37 complex regulated cyclin-dependent kinase 2 (CDK2) activation and then triggered breast cancer cell proliferation. In summary, our results identified a new lncRNA regulate breast cancer proliferation though interaction with HSP90.

Deficient Regulatory Innate Lymphoid Cells and Differential Expression of miRNAs in Acute Myeloid Leukemia Quantified by Next Generation Sequence

Background

A new regulatory subpopulation of ILCs, ILCreg has been identified in mouse and human intestines. ILCregs share characteristics with both innate lymphoid cells and regulatory cells; however, the significance of CD45⁺Lin^-CD127⁺IL-10⁺ ILCregs in patients with AML remains unclear. Intriguingly, ILCregs constitutively express id2, id3, sox4, tgfbr1, tgfbr2, il2rb and il2rg, but the significance of miRNAs associated with these genes has yet to be explored. In this study, we evaluate ILCreg frequency, ILCreg gene-associated miRNA quantification, and its significance in patients with AML and normal donors.

Methods

Using 4 color combinations of surface and intracellular antibody staining, the CD45⁺Lin^-CD127⁺IL-10⁺ ILCregs from 12 normal donors and 42 patients newly diagnosed with AML were measured by flow cytometry. Plasma samples and bone marrow cells from 6 normal donors and 9 patients with AML were studied by next-generation sequence miRNAs quantification.

Results

Our results showed that the frequency of ILCregs was 0.8924±1.3791% in bone marrow (BM) cells from normal donors and 0.2434±0.5344% in BM cells from AML patients. The frequency of ILCreg cells in AML patients was significantly lower than that in normal donors (P<0.01). Furthermore, the frequency of the CD45⁺Lin^-CD127⁺IL-10^- subset was 4.0869±6.7701% and 0.2769±0.2526% from normal donors and AML patients, respectively. There was a statistically significant difference of CD45⁺Lin^-CD127⁺IL-10^- cells between normal donors and AML patients (p<0.01). miRNA detection results showed 376 miRNAs from plasma and 182 miRNAs from BM cell samples with expression levels with a statistically significant difference between AML patients and normal donors (both Q and P-value < 0.001). Analysis of miRNAs from ILCregs associated genes including id2, id3, sox4, tgfbr1, tgfbr2, il2rb, and il3rg, from normal donors and AML patients demonstrated 34 miRNA from plasma samples and 14 miRNA segments from BM cell samples with a statistically significant difference between AML patients and normal donors (both Q and P-value <0.001). Among them, 4 miRNAs (hsa-miR-193b-3p, hsa-miR-1270, hsa-miR-210-3p, and hsa-miR-486-3p) were detected in both plasma and BM cell samples.

Conclusion

Our study enumerated ILCregs, then measured miRNAs from those ILCregs in AML samples for the first time. The results demonstrated the deficiency of ILCreg and differential expression of miRNAs in patients with AML.

Acute myeloid leukemia cells secrete microRNA-4532-containing exosomes to mediate normal hematopoiesis in hematopoietic stem cells by activating the LDOC1-dependent STAT3 signaling pathway

BACKGROUND

MicroRNA (miR)-containing exosomes released by acute myeloid leukemia (AML) cells can be delivered into hematopoietic progenitor cells to suppress normal hematopoiesis. Herein, our study was performed to evaluate the effect of exosomal miR-4532 secreted by AML cells on hematopoiesis of hematopoietic stem cells.

METHODS

Firstly, differentially expressed miRs related to AML were identified using microarray analysis. Subsequently, AML cell lines were collected, and CD34+ HSCs were isolated from healthy pregnant women. Then, miR-4532 expression was measured in AML cells and AML cell-derived exosomes and CD34+ HSCs, together with evaluation of the targeting relationship between miR-4532 and LDOC1. Then, AML cells were treated with miR-4532 inhibitor, and exosomes were separated from AML cells and co-cultured with CD34+ HSCs. Gain- and loss-function approaches were employed in CD34+ HSCs. Colony-forming units (CFU) and expression of dickkopf-1 (DKK1), a hematopoietic inhibiting factor associated with pathogenesis of AML, were determined in CD34+ HSCs, as well as the extents of JAK2 and STAT3 phosphorylation and LDOC1 expression.

RESULTS

miR-4532 was found to be upregulated in AML cells and AML cell-derived exosomes, while being downregulated in CD34+ HSCs. In addition, exosomes released by AML cells targeted CD34+ HSCs to decrease the expression of CFU and increase the expression of DKK1. miR-4532 was delivered into CD34+ HSCs to target LDOC1 via AML cell-released exosomes. AML cell-derived exosomes containing miR-4532 inhibitor increased CFU but reduced DKK1 in CD34+ HSCs. Inhibition of miR-4532 or JAK2, or ectopic expression of LDOC1 upregulated CFU and downregulated DKK1 expression as well as the extents of JAK2 and STAT3 phosphorylation in CD34+ HSCs.

CONCLUSION

In conclusion, AML cell-derived exosomes carrying miR-4532 repress normal HSC hematopoiesis via activation of the LDOC1-dependent STAT3 signaling pathway.

Assessment of the Diagnostic Potential of miR-29a-3p and miR-92a-3p as Circulatory Biomarkers in Acute Myeloid Leukemia

Background:

Acute myeloid leukemia (AML) is a set of Myeloproliferative neoplasms that are identified by excessive growth of myeloid blasts and production of abnormal blood cells. AML is the most common type of acute leukemia that occurs in adults. In addition, AML progresses rapidly and is considered a fatal disease. Thus, there is an urgent need to find new targets for molecularly designed therapies. In This study, we evaluated the circulatory levels of microRNA-29a-3p (miR-29a-3p) and miR-92a-3p beside exploring the expression pattern of their target gene myeloid cell leukemia sequence1 (MCL1) to investigate the role of these molecules in AML pathophysiology and to assess their ability to diagnose AML patients.

Methods:

40 adult AML patients along with 20 healthy subjects were enrolled in this study. Plasma were separated from venous blood samples, collected on EDTA, of all individuals were used to assess circulating miRNAs’ levels. In the meantime, total RNA was extracted from isolated leukocytes and was used to quantify target mRNA transcript levels.

Results:

Our data revealed that the circulating levels of miR-29a-3p and miR-92a-3p exhibited significant reduction in 90% and 100% of AML patients, respectively, when compared to the control group (p<0.001). On the other hand, the transcript level of the target gene of these miRNAs, MCL1, showed a sharp increase in 77.5% (p<0.001) of AML patients, along with a negative correlation with its regulatory miRNAs, miR-29a-3p and miR-92a-3p.

Conclusion:

Our data validates the negative regulatory role of miR-29a-3p and miR-92a-3p to the expression levels of MCL1 in peripheral blood and indicates that these miRNAs can be used as non-invasive diagnostic markers. Furthermore, our study highlights the therapeutic potential of miR-29a-3p and miR-92a-3p to target and downregulate a very important gene (MCL1), which is highly implicated in the pathogenesis of AML.

Advances in Genomic Profiling and Risk Stratification in Acute Myeloid Leukemia

OBJECTIVE

To review the current state of molecular and genetic profiling of acute myeloid leukemia (AML) and its implications.

DATA SOURCE

Peer-reviewed journal articles.

CONCLUSION

Significant advances in the understanding of the pathology of acute myeloid leukemia have led to refined risk stratification of patients and application of novel targeted therapies based on genetic profiles. Minimal residual disease testing allows for highly sensitive disease surveillance that can be used to predict relapse and assess treatment response.

IMPLICATIONS FOR NURSING PRACTICE

Accurate prognostication and therapeutic decision-making for patients with acute myeloid leukemia is dependent on molecular profiling. Being knowledgeable of the implications of minimal residual disease testing is critical for patient-centered care.

Exosomal MiRNAs in Pediatric Cancers

MicroRNAs (miRNAs) have generated great attention in oncology as they play a fundamental role in the regulation of gene expression and their aberrant expression is present in almost all types of tumors including pediatric ones. The discovery that miRNAs can be transported by exosomes, which are vesicles of 40–120 nm involved in cellular communication, that are produced by different cell types, and that are present in different biological fluids, has opened the possibility of using exosomal miRNAs as biomarkers. The possibility to diagnose and monitor the progression and response to drugs through molecules that can be easily isolated from biological fluids represents a particularly important aspect in the pediatric context where invasive techniques are often used. In recent years, the idea of liquid biopsy as well as studies on the possible role of exosomal miRNAs as biomarkers have developed greatly. In this review, we report an overview of all the evidences acquired in recent years on the identification of exosomal microRNAs with biomarker potential in pediatric cancers. We discuss the following herein: neuroblastoma, hepatoblastoma, sarcomas (osteosarcoma, Ewing’s sarcoma and rhabdoid tumors, and non-rhabdomyosarcoma soft tissue sarcoma), brain tumors, lymphomas, and leukemias.

Aberrant Expression of the miR-181b/miR-222 after Hematopoietic Stem Cell Transplantation in Patients with Acute Myeloid Leukemia

Recently, dysregulated expression of various micro RNAs has been reported in hematologic malignancies, especially AML disease which affects normal hematopoiesis in these patients and thereby contribute to clinical outcome of AML patients, associated with either poor or favorable prognosis. Herein, we evaluated the expression of miR-181b and miR-222 in acute myeloid leukemia patients and correlation with response to therapy after hematopoietic stem cell transplantation. Eighty newly diagnosed AML patients and 80 healthy controls were recruited. The expression of miR-181b and miR-222 was evaluated by real-time SYBR Green PCR method. miR-181b gene expression was significantly increased (4.7 fold) whereas miR-222 was decreased (18.3 fold) in AML patients compared to controls (P = 0.03 and P < 0.001, respectively). Both miR-181b and miR-222 were not associated with response to treatment (P > 0.05). Also, miR-181b and miR-222 were not differentially expressed in AML patients with M3 compared to non-M3 FAB subtypes (P > 0.05). miR-181b and miR-222 are aberrantly expressed in AML patients and their baseline level is not associated with response to treatment.

HDAC2-dependent miRNA signature in acute myeloid leukemia

Acute myeloid leukemia (AML) arises from a complex sequence of biological and finely orchestrated events that are still poorly understood. Increasingly, epigenetic studies are providing exciting findings that may be exploited in promising and personalized cutting‐edge therapies. A more appropriate and broader screening of possible players in cancer could identify a master molecular mechanism in AML. Here, we build on our previously published study by evaluating a histone deacetylase (HDAC)2‐mediated miRNA regulatory network in U937 leukemic cells. Following a comparative miRNA profiling analysis in genetically and enzymatically HDAC2‐downregulated AML cells, we identified miR‐96‐5p and miR‐92a‐3p as potential regulators in AML etiopathology by targeting defined genes. Our findings support the potentially beneficial role of alternative physiopathological interventions.

MicroRNA-425 upregulation indicates better prognosis in younger acute myeloid leukemia patients undergoing chemotherapy

The aim of the present study was to investigate whether the expression levels of microRNA-425 (miR-425) were associated with the prognosis of acute myeloid leukemia (AML) in patients treated with chemotherapy or allogeneic hematopoietic stem cell transplantation (allo-HSCT). A total of 162 AML patients were enrolled and divided into chemotherapy and allo-HSCT groups. Next, the overall survival (OS) and event-free survival (EFS) were compared between patients with high and low miR-425 expression in each of the treatment groups. In the chemotherapy group, high miR-425 expression was favorable for EFS (P=0.001) and OS (P=0.001) in younger patients (<60 years), whereas it had no effect on EFS and OS in older patients (≥60 years). In the allo-HSCT group, there was no association between miR-425 expression levels and clinical outcomes. Further analyses suggested that in the low miR-425 expression group, EFS and OS were longer in patients treated with allo-HSCT as compared with those treated with chemotherapy (both P<0.001), whereas no significant differences were observed in the high miR-425 expression group. In conclusion, the current data indicated that miR-425 is an independent favorable prognostic factor for younger AML patients undergoing chemotherapy, and its use may facilitate clinical decision-making in selecting treatment for AML patients. Patients with low miR-425 expression may benefit from allo-HSCT, whereas allo-HSCT did not appear to be beneficial in patients with high miR-425 expression.