MicroRNA-139-5p regulates proliferation of hematopoietic progenitors and is repressed during BCR-ABL-mediated leukemogenesis

miR-181a plays the tumor-suppressor role in chronic myeloid leukemia CD34 + cells partially via SERPINE1

The formation of the BCR-ABL fusion gene drives human chronic myeloid leukemia (CML). The last 2 decades have witnessed that specific tyrosine kinase inhibitors (TKIs, e.g., imatinib mesylate, IM) against ABL1 improve disease treatment, although some patients still suffer from relapse and TKI resistance. Therefore, a better understanding of the molecular pathology of CML is still urgently needed. miR-181a-5p (miR-181a) acts as a tumor suppressor in CML; however, the molecular mechanism of miR-181a in CML stem/progenitor cells remains elusive. Herein, we showed that miR-181a inhibited the growth of CML CD34+ cells, including the quiescent subset, and sensitized them to IM treatment, while miR-181a inhibition by a sponge sequence collaborated with BCR-ABL to enhance the growth of normal CD34+ cells. Transcriptome data and biochemical analysis revealed that SERPINE1 was a bona fide and critical target of miR-181a, which deepened the understanding of the regulatory mechanism of SERPINE1. Genetic and pharmacological inhibition of SERPINE1 led to apoptosis mainly mediated by caspase-9 activation. The dual inhibition of SERPINE1 and BCR-ABL exhibited a significantly stronger inhibitory effect than a single agent. Taken together, this study demonstrates that a novel miR-181a/SERPINE1 axis modulates CML stem/progenitor cells, which likely provides an important approach to override TKI resistance.

Dysregulation of miRNA expression in patients with chronic myelogenous leukemia at diagnosis: a systematic review

Aim: The present systematic review aimed to explore miRNAs as a potential biomarker for early diagnosis of chronic myeloid leukemia (CML). Materials & methods: A systematic search was conducted in three electronic databases, including Web of Science, Scopus and PubMed, to obtain relevant articles investigating the alteration of miRNA expression in patients with CML. Results: The authors found miRNAs whose expression changes are effective in the induction of CML disease. Among them, miR-21 and miR-155 were identified as the most common miRNAs with increased expression and miR-150 and miR-146 as the most common miRNAs with decreased expression. Conclusion: miRNAs can be used as an indicator for the early detection and treatment of CML phase.

SWI/SNF complexes in hematological malignancies: biological implications and therapeutic opportunities

Hematological malignancies are a highly heterogeneous group of diseases with varied molecular and phenotypical characteristics. SWI/SNF (SWItch/Sucrose Non-Fermentable) chromatin remodeling complexes play significant roles in the regulation of gene expression, being essential for processes such as cell maintenance and differentiation in hematopoietic stem cells. Furthermore, alterations in SWI/SNF complex subunits, especially in ARID1A/1B/2, SMARCA2/4, and BCL7A, are highly recurrent across a wide variety of lymphoid and myeloid malignancies. Most genetic alterations cause a loss of function of the subunit, suggesting a tumor suppressor role. However, SWI/SNF subunits can also be required for tumor maintenance or even play an oncogenic role in certain disease contexts. The recurrent alterations of SWI/SNF subunits highlight not only the biological relevance of SWI/SNF complexes in hematological malignancies but also their clinical potential. In particular, increasing evidence has shown that mutations in SWI/SNF complex subunits confer resistance to several antineoplastic agents routinely used for the treatment of hematological malignancies. Furthermore, mutations in SWI/SNF subunits often create synthetic lethality relationships with other SWI/SNF or non-SWI/SNF proteins that could be exploited therapeutically. In conclusion, SWI/SNF complexes are recurrently altered in hematological malignancies and some SWI/SNF subunits may be essential for tumor maintenance. These alterations, as well as their synthetic lethal relationships with SWI/SNF and non-SWI/SNF proteins, may be pharmacologically exploited for the treatment of diverse hematological cancers.

PCGF1-PRC1 links chromatin repression with DNA replication during hematopoietic cell lineage commitment

Polycomb group proteins (PcG), polycomb repressive complexes 1 and 2 (PRC1 and 2), repress lineage inappropriate genes during development to maintain proper cellular identities. It has been recognized that PRC1 localizes at the replication fork, however, the precise functions of PRC1 during DNA replication are elusive. Here, we reveal that a variant PRC1 containing PCGF1 (PCGF1-PRC1) prevents overloading of activators and chromatin remodeling factors on nascent DNA and thereby mediates proper deposition of nucleosomes and correct downstream chromatin configurations in hematopoietic stem and progenitor cells (HSPCs). This function of PCGF1-PRC1 in turn facilitates PRC2-mediated repression of target genes such as Hmga2 and restricts premature myeloid differentiation. PCGF1-PRC1, therefore, maintains the differentiation potential of HSPCs by linking proper nucleosome configuration at the replication fork with PcG-mediated gene silencing to ensure life-long hematopoiesis.

LncRNA Snhg1 Plays an Important Role via Sequestering rno-miR-139-5p to Function as a ceRNA in Acute Rejection After Rat Liver Transplantation Based on the Bioinformatics Analysis

In order to explore the molecular mechanism of acute rejection after liver transplantation (ARLT) in rats, we employed the GSE36798 data set in the Gene Expression Omnibust (GEO) database to construct a related ceRNA network. This dataset contained a total of 16 samples (8 graft samples and 8 plasma samples). Each kind of sample was divided into acute rejection (AR) groups and non-acute rejection (NR) groups, and each group had 4 replicates. First, we performed principal component analysis (PCA) with downloaded data to compare the difference between samples in a macroscopic way. Then, we used the “limma” R package to screen out differentially expressed miRNAs among different groups and used the “pheatmap” R package to perform bidirectional hierarchical clustering analysis for these differentially expressed miRNAs. The miRWalk database and the LncBase V.2 database were applied to predict downstream target genes and upstream-related lncRNAs, respectively. Meanwhile, the String database was used to predict the relationship between target genes, and the aforementioned results were processed for visualization by Cytoscape software. In addition, we exhibited the ultimate ceRNA network, including two lncRNAs, two miRNAs, and 77 mRNAs. Finally, we constructed a rat model of ARLT and applied graft specimens to relevant experimental verification. We found that the lncRNA Snhg1/rno-miR-139-5p axis might be involved in the regulation of ARLT in rats. In short, we demonstrated the differentially expressed miRNA profile, constructed a related ceRNA network, and screened out a possible regulatory axis. In view of the conservation of genes among species, this work was expected to provide a new strategy for the treatment and prevention of ARLT in the clinical setting.

5-Azacytidine Downregulates the Proliferation and Migration of Hepatocellular Carcinoma Cells In Vitro and In Vivo by Targeting miR-139-5p/ROCK2 Pathway

Simple Summary

For hepatocellular carcinoma (HCC), the second most common cause of cancer-related death, effective therapeutic approaches are lacking. As aberrant gene methylation is a major contributor to the development of HCC, demethylating drugs such as 5-azacytidine (5-Aza) have been proposed. However, despite the potential efficacy of 5-Aza in HCC, most of its mechanisms of action are still unknown. Here, we investigate the phenotypic/molecular effects of 5-Aza with a focus on miR-139-5p. Using multiple in vitro and in vivo models of HCC, we show for the first time that 5-Aza can impair HCC development via upregulation of miR-139-5p, which in turn downregulates the ROCK2/cyclin D1/E2F1/cyclin B1 pro-proliferative pathway and the ROCK2/MMP-2 pro-migratory pathway. These observations elucidate the mechanisms of action of 5-Aza in HCC, strengthen its therapeutic potential, and provide novel information about the crosstalk among ROCK2/cyclin D1/E2F1/cyclin B1/MMP-2 in HCC.

Abstract

Background: For hepatocellular carcinoma (HCC), effective therapeutic approaches are lacking. As aberrant gene methylation is a major contributor to HCC development, demethylating drugs such as 5-azacytidine (5-Aza) have been proposed. As most 5-Aza mechanisms of action are unknown, we investigated its phenotypic/molecular effects. Methods: 5-Aza effects were examined in the human HCC cell lines JHH-6/HuH-7 and in the rat cell-line N1-S1. We also employed a xenograft mouse model (HuH-7), a zebrafish model (JHH-6), and an orthotopic syngeneic rat model (N1-S1) of HCC. Results: 5-Aza downregulated cell viability/growth/migration/adhesion by upregulating miR-139-5p, which in turn downregulated ROCK2/cyclin D1/E2F1 and increased p27^kip1, resulting in G1/G0 cell accumulation. Moreover, a decrease in cyclin B1 and an increase in p27^kip1 led to G2/M accumulation. Finally, we observed a decrease in MMP-2 levels, a stimulator of HCC cell migration. Aza effects were confirmed in the mouse model; in the zebrafish model, we also demonstrated the downregulation of tumor neo-angiogenesis, and in the orthotopic rat model, we observed impaired N1-S1 grafting in a healthy liver. Conclusion: We demonstrate for the first time that 5-Aza can impair HCC development via upregulation of miR-139-5p, which in turn impairs the ROCK2/cyclin D1/E2F1/cyclin B1 pro-proliferative pathway and the ROCK2/MMP-2 pro-migratory pathway. Thus, we provide novel information about 5-Aza mechanisms of action and deepen the knowledge about the crosstalk among ROCK2/cyclin D1/E2F1/cyclin B1/p27^kip1/MMP-2 in HCC.

MicroRNA-139, an Emerging Gate-Keeper in Various Types of Cancer

Mounting data show that MIR139 is commonly silenced in solid cancer and hematological malignancies. MIR139 acts as a critical tumor suppressor by tuning the cellular response to different types of stress, including DNA damage, and by repressing oncogenic signaling pathways. Recently, novel insights into the mechanism of MIR139 silencing in tumor cells have been described. These include epigenetic silencing, inhibition of POL-II transcriptional activity on gene regulatory elements, enhanced expression of competing RNAs and post-transcriptional regulation by the microprocessor complex. Some of these MIR139-silencing mechanisms have been demonstrated in different types of cancer, suggesting that these are more general oncogenic events. Reactivation of MIR139 expression in tumor cells causes inhibition of tumor cell expansion and induction of cell death by the repression of oncogenic mRNA targets. In this review, we discuss the different aspects of MIR139 as a tumor suppressor gene and give an overview on different transcriptional mechanisms regulating MIR139 in oncogenic stress and across different types of cancer. The novel insights into the expression regulation and the tumor-suppressing activities of MIR139 may pave the way to new treatment options for cancer.

MicroRNA-139 Expression Is Dispensable for the Generation of Influenza-Specific CD8+ T Cell Responses

MicroRNAs (miRNAs/miRs) are small, endogenous noncoding RNAs that are important post-transcriptional regulators with clear roles in the development of the immune system and immune responses. Using miRNA microarray profiling, we characterized the expression profile of naive and in vivo generated murine effector antiviral CD8⁺ T cells. We observed that out of 362 measurable mature miRNAs, 120 were differentially expressed by at least 2-fold in influenza-specific effector CD8⁺ CTLs compared with naive CD8⁺ T cells. One miRNA found to be highly downregulated on both strands in effector CTLs was miR-139. Because previous studies have indicated a role for miR-139-mediated regulation of CTL effector responses, we hypothesized that deletion of miR-139 would enhance antiviral CTL responses during influenza virus infection. We generated miR-139^-/- mice or overexpressed miR-139 in T cells to assess the functional contribution of miR-139 expression in CD8⁺ T cell responses. Our study demonstrates that the development of naive T cells and generation or differentiation of effector or memory CD8⁺ T cell responses to influenza virus infection are not impacted by miR-139 deficiency or overexpression; yet, miR-139^-/- CD8⁺ T cells are outcompeted by wild-type CD8⁺ T cells in a competition setting and demonstrate reduced responses to Listeria monocytogenes Using an in vitro model of T cell exhaustion, we confirmed that miR-139 expression similarly does not impact the development of T cell exhaustion. We conclude that despite significant downregulation of miR-139 following in vivo and in vitro activation, miR-139 expression is dispensable for influenza-specific CTL responses.

Long noncoding RNA lnc-NAP sponges mmu-miR-139-5p to modulate Nanog functions in mouse ESCs and embryos

The pluripotency of embryonic stem cells (ESCs) is controlled by a multilayer regulatory network, of which the key factors include core pluripotency genes Oct4, Sox2 and Nanog, and multiple microRNAs (miRNAs). Recently, long noncoding RNAs (lncRNAs) have been discovered as a class of new regulators for ESCs, and some lncRNAs could function as competing endogenous RNAs (ceRNAs) to regulate mRNAs by competitively binding to miRNAs. Here, we identify mmu-miR-139-5p as a new regulator for Nanog by targeting Nanog 3' untranslated region (UTR) to repress Nanog expression in mouse ESCs and embryos. Such regulation could be released by an ESC-specifically expressed ceRNA named lnc-NAP. The expression of lnc-NAP is activated by OCT4, SOX2, as well as NANOG through promoter binding. Downregulation of lnc-NAP reduces Nanog abundance, which leads to decreased pluripotency of mouse ESCs and embryonic lethality. These results reveal lnc-NAP as a new regulator for Nanog in mouse ESCs, and uncover a feed-forward regulatory loop of Nanog through the participation of lnc-NAP.

miR-139-5p Regulates the Proliferation of Acute Promyelocytic Leukemia Cells by Targeting MNT

Acute promyelocytic leukemia (APL) patients with progressive leukocytosis are more likely to have various complications and poor outcomes. However, the regulatory roles of microRNAs in the leukocytosis of APL have not been clarified. Our study aims to evaluate the effects of miRNAs on leukocytosis during induction therapy of APL patients and explore its potential mechanisms. During induction treatment, patients with white blood cell count higher than 10 × 10⁹/L were divided into leukocytosis group and others were nonleukocytosis group. Using microarray assays, we found that miR-139-5p was significantly downregulated in the leukocytosis group. Elevated expression of miR-139-5p inhibited the proliferation of NB4 cells by arresting the cell cycle and inducing apoptosis. We further identified that MNT was a target of miR-139-5p. miR-139-5p significantly inhibited the proliferation, invasion, and migration function of NB4 cells through targeting MNT. Strategies for regulating miR-139-5p or MNT expression might provide new therapeutic approaches for progressive leukocytosis in APL.

Immunosuppressive Cell Subsets and Factors in Myeloid Leukemias

Simple Summary

Effector immune system cells have the ability to kill tumor cells. However, as a cancer (such as leukemia) develops, it inhibits and evades the effector immune response. Such a state of immunosuppression can be driven by several factors – receptors, soluble cytokines, as well as by suppressive immune cells. In this review, we describe factors and cells that constitute immunosuppressive microenvironment of myeloid leukemias. We characterize factors of direct leukemic origin, such as inhibitory receptors, enzymes and extracellular vesicles. Furthermore, we describe suppressive immune cells, such as myeloid derived suppressor cells and regulatory T cells. Finally, we sum up changes in these drivers of immune evasion in myeloid leukemias during therapy.

Abstract

Both chronic myeloid leukemia and acute myeloid leukemia evade the immune response during their development and disease progression. As myeloid leukemia cells modify their bone marrow microenvironment, they lead to dysfunction of cytotoxic cells, such as CD8+ T cells or NK cells, simultaneously promoting development of immunosuppressive regulatory T cells and suppressive myeloid cells. This facilitates disease progression, spreading of leukemic blasts outside the bone marrow niche and therapy resistance. The following review focuses on main immunosuppressive features of myeloid leukemias. Firstly, factors derived directly from leukemic cells – inhibitory receptors, soluble factors and extracellular vesicles, are described. Further, we outline function, properties and origin of main immunosuppressive cells - regulatory T cells, myeloid derived suppressor cells and macrophages. Finally, we analyze interplay between recovery of effector immunity and therapeutic modalities, such as tyrosine kinase inhibitors and chemotherapy.

miR-139-5p protects septic mice with acute lung injury by inhibiting Toll-like receptor 4/Myeloid differentiation factor 88/Nuclear factor-&mac_kgr;B signaling pathway

OBJECTIVES

To investigate the role of miR-139-5p and the TLR4/MyD88/NF-κB signaling pathway in acute lung injury in septic mice.

METHOD

A total of 140 healthy male SPF C57BL/6 mice were divided into seven groups, i.e., Normal, Control, NC, miR-139-5p mimic, miR-139-5p inhibitor, TAK-242, and miR-139-5p inhibitor+TAK-242 groups. The levels of miR-139-5p, proteins related to the TLR4/MyD88/NF-κB signaling pathway (TLR4, MyD88, and p-NF-κB p50), and MPO, SOD, GSH, and MDA in lung tissue were measured. The lung tissue wet-to-dry mass ratio (W/D), arterial oxygen partial pressure (PaO2), and carbon dioxide partial pressure (PaCO2) were measured.

RESULTS

A web-based bioinformatic tool predicted that MyD88 was a target of miR-139-5p, which was verified by a dual luciferase reporter assay. Compared with those in the Normal group, the levels of miR-139-5p, PaO2, SOD, and GSH were significantly lower, while those of TLR4, MyD88, p-NF-κB p50, W/D, PaCO2, IL-1β, TNF-α, IL-6, MPO, and MDA were higher in all other groups. Moreover, compared with their levels in the Control group, these indicators exhibited contrasting results in the miR-139-5p mimic and TAK-242 groups, but were similar in the miR-139-5p inhibitor group. In the miR-139-5p inhibitor+TAK-242 group, acute lung injury, aggravated by miR-139-5p inhibitor, was partially rescued by TAK-242.

CONCLUSION

miR-139-5p inhibits the TLR4/MyD88/NF-κB signaling pathway to alleviate acute lung injury in septic mice.

The Role of BRG1 in Antioxidant and Redox Signaling

Redox homeostasis is regulated by critical molecules that modulate antioxidant and redox signaling (ARS) within the cell. Imbalances among these molecules can lead to oxidative stress and damage to cell functions, causing a variety of diseases. Brahma-related gene 1 (BRG1), also known as SMARCA4, is the central ATPase catalytic subunit of the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex, which plays a core role in DNA replication, repair, recombination, and transcriptional regulation. Numerous recent studies show that BRG1 is involved in the regulation of various cellular processes associated with ARS. BRG1, as a major factor in chromatin remodeling, is essential for the repair of oxidative stress-induced DNA damage and the activation of antioxidant genes under oxidative stress. Consequently, a comprehensive understanding of the roles of BRG1 in redox homeostasis is crucial to understand the normal functioning as well as pathological mechanisms. In this review, we summarized and discussed the role of BRG1 in the regulation of ARS.

Non-coding RNAs in cancers with chromosomal rearrangements: the signatures, causes, functions and implications

Chromosomal translocation leads to the juxtaposition of two otherwise separate DNA loci, which could result in gene fusion. These rearrangements at the DNA level are catastrophic events and often have causal roles in tumorigenesis. The oncogenic DNA messages are transferred to RNA molecules, which are in most cases translated into cancerous fusion proteins. Gene expression programs and signaling pathways are altered in these cytogenetically abnormal contexts. Notably, non-coding RNAs have attracted increasing attention and are believed to be tightly associated with chromosome-rearranged cancers. These RNAs not only function as modulators in downstream pathways but also directly affect chromosomal translocation or the associated products. This review summarizes recent research advances on the relationship between non-coding RNAs and chromosomal translocations and on diverse functions of non-coding RNAs in cancers with chromosomal rearrangements.

MicroRNAs in hematopoietic stem cell aging

The functional decline that is observed in HSCs upon aging is attributed mainly to cell intrinsic factors that regulate quiescence, self-renewal and differentiation. MicroRNAs (miRs) have an indispensable role in the regulation of HSCs and have been shown to also regulate processes related to tissue aging in specific cell types. Here we discuss the role of miRs in the regulation of HSC self-renewal and differentiation throughout life and its implications for future research.

Diagnostic, prognostic, and therapeutic significance of miR-139-5p in cancers

miRNAs are a group of non-coding RNAs that have regulatory functions in post-transcriptional gene expression. These molecules play a fundamental role in cellular processes, for instance cell proliferation, apoptosis, migration, and invasion. Scientific investigations have previously established that miRNAs can either promote or suppress tumor development by mediating different signaling pathways. miR-139-5p, located on chromosome 11q13.4, has been examined extensively in cancers. Studies have demonstrated that miR-139-5p might be an attractive cancer biomarker. Herein, we will review how miR-139-5p acts in cancer diagnosis, prognosis, and therapy, as well as elucidating its major target genes and associated signaling pathways.

MiR-139-5p negatively regulates PMP22 to repress cell proliferation by targeting the NF-κB signaling pathway in gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors worldwide. Peripheral myelin protein 22 (PMP22) is a 22-kDa tetraspan glycoprotein that is predominantly expressed by myelinating Schwann cells. However, recent studies have shown that PMP22 is closely related to cell proliferation and tumorigenesis in different cancers. In this study, we discovered a new miRNA that regulates PMP22 and gastric cancer cell prolifration. Our bioinformatics analysis suggested that there is a conserved miRNA recognition site for miR-139-5p on the 3' UTR of PMP22. Interestingly, our results showed overexpression of miR-139-5p significantly suppressed growth and prolifration in GC cells and inhibited tumor growth in nude mice xenografted with GC cells. MiR-139-5p suppressed the activity of a luciferase reporter containing the PMP22-3' UTR, and the ectopic expression of PMP22 rescued the miR-139-5p-mediated inhibition of cell proliferation in GC cells. Mechanistically, miR-139-5p may negatively regulate PMP22 to repress cell proliferation by targeting the NF-κB signaling pathway in gastric cancer. Finally, overexpression of miR-139-5p significantly inhibited tumor growth in nude mice xenografted with GC cells.and the miR-139-5p levels were inversely correlated with PMP22 expression in nude mice tumor. Taken together, our data suggest an important regulatory role of miR-139-5p in gastric cancer, suggesting that miR-139-5p and PMP22 might be important diagnostic or therapeutic targets for gastric cancer and other human diseases.

MicroRNA-139 is a predictor of prostate cancer recurrence and inhibits growth and migration of prostate cancer cells through cell cycle arrest and targeting IGF1R and AXL

BACKGROUND

We previously identified a panel of five microRNAs (miRNAs) associated with biochemical recurrence and metastasis following prostatectomy from prostate cancer patients using next-generation sequencing-based whole miRNome sequencing and quantitative polymerase chain reaction-based validation analysis. In this study, we examined the mechanism of action of miR-139-5p, one of the downregulated miRNAs identified in the panel.

METHODS

Using a cohort of 585 patients treated with radical prostatectomy, we examined the prognostic significance of miR-139 (dichotomized around the median) using the Kaplan-Meier method and Cox proportional hazard models. We validated these results using The Cancer Genome Atlas (TCGA) data. We created cell lines that overexpressed miR-139 to confirm its targets as well as examine pathways through which miR-139 may function using cell-based assays.

RESULTS

Low miR-139 expression was significantly associated with a variety of prognostic factors in prostate cancer, including Gleason score, pathologic stage, margin positivity, and lymph node status. MiR-139 expression was associated with prognosis: the cumulative incidence of biochemical recurrence and metastasis were significantly lower among patients with high miR-139 expression (P = .0004 and .038, respectively). Validation in the TCGA data set showed a significant association between dichotomized miR-139 expression and biochemical recurrence (odds ratio, 0.52; 95% confidence interval, 0.33-0.82). Overexpression of miR-139 in prostate cancer cells led to a significant reduction in cell proliferation and migration compared with control cells, with cells arrested in G2 of cell cycle. IGF1R and AXL were identified as potential targets of miR-139 based on multiple miRNA-binding sites in 3'-untranslated regions of both the genes and their association with prostate cancer growth pathways. Luciferase assays verified AXL and IGF1R as direct targets of miR-139. Furthermore, immunoblotting of prostate cancer cells demonstrated IGF1R and AXL protein expression were inhibited by miR-139 treatment, which was reversed by the addition of miR-139 antagomir. Examination of the molecular mechanism of growth inhibition by miR-139 revealed the downregulation of activated AKT and cyclin D1, with upregulation of the CDK inhibitor p21.

CONCLUSIONS

miR-139 is associated with improved prognosis in patients with localized prostate cancer, which may be mediated through downregulation of IGF1R and/or AXL and associated signaling pathway components.

MicroRNA 34a promotes ionizing radiation-induced DNA damage repair in murine hematopoietic stem cells

Hematopoietic stem cells (HSCs) establish the entire hematopoietic system and maintain lifelong hematopoiesis. Previous studies have reported the significance of microRNAs (miRNAs) in the regulation of self-renewal and differentiation of HSCs. In this study, we show that the expression of miRNA 34a (miR-34a) is markedly up-regulated in HSCs from mice subjected to ionizing radiation (IR). Reduced numbers and DNA damage repair, as well as increased apoptosis, are observed in HSCs from miR-34a-deficient mice induced by irradiation, although miR-34a is dispensable for steady-state hematopoiesis. Further investigations show that HSCs deficient in miR-34a exhibit decreased expressions of DNA repair-associated genes involved in homologous recombination and nonhomologous end joining. Competitive transplantation confirms that loss of miR-34a leads to more severe impairment of the long-term hematopoietic function of HSCs after irradiation exposure. Consistently, treating mice with an miR-34a agomir can significantly alleviate irradiation-induced DNA damage in HSCs. Our findings demonstrate that miR-34a contributes to promoting HSCs' survival after irradiation, which provides a promising approach for protecting HSCs from IR.-Zeng, H., Hu, M., Lu, Y., Zhang, Z., Xu, Y., Wang, S., Chen, M., Shen, M., Wang, C., Chen, F., Du, C., Tang, Y., Su,Y., Chen, S., Wang, J. MicroRNA 34a promotes ionizing radiation-induced DNA damage repair in murine hematopoietic stem cells.

MicroRNA in leukemia: Tumor suppressors and oncogenes with prognostic potential

Leukemia is known as a progressive malignant disease, which destroys the blood-forming organs and results in adverse effects on the proliferation and development of leukocytes and their precursors in the blood and bone marrow. There are four main classes of leukemia including acute leukemia, chronic leukemia, myelogenous leukemia, and lymphocytic leukemia. Given that a variety of internal and external factors could be associated with the initiation and progression of different types of leukemia. One of the important factors is epigenetic regulators such as microRNAs (miRNAs) and long noncoding RNAs (ncRNA). MiRNAs are short ncRNAs which act as tumor suppressor (i.e., miR-15, miR-16, let-7, and miR-127) or oncogene (i.e., miR-155, miR-17-92, miR-21, miR-125b, miR-93, miR-143-p3, miR-196b, and miR-223) in leukemia. It has been shown that deregulation of these molecules are associated with the initiation and progression of leukemia. Hence, miRNAs could be used as potential therapeutic candidates in the treatment of patients with leukemia. Moreover, increasing evidence revealed that miRNAs could be used as diagnostic and prognostic biomarkers in monitoring patients in early stages of disease or after received chemotherapy regimen. It seems that identification and development of new miRNAs could pave to the way to the development new therapeutic platforms for patients with leukemia. Here, we summarized various miRNAs as tumor suppressor and oncogene which could be introduced as therapeutic targets in treatment of leukemia.

MiRNA-142-3p increases radiosensitivity in human umbilical cord blood mononuclear cells by inhibiting the expression of CD133

This study is to explore the molecular regulation mechanism of CD133 which is associated with malignancy and poor prognosis of blood system diseases. CD133+HUCB-MNC (human umbilical cord blood mononuclear cells) and CD133-HUCB-MNC were isolated and amplificated from umbilical cord blood, and then were exposed to different doses of radiation and subjected to a clonogenic assay. CCK-8 kit was used to detect cell viability, Annexin V-FITC/PI cell apoptosis detection kit was used for the detection of apoptotic cells and the BrdU assay was performed by flow cytometry. The expression of protein was analyzed by western blots. The profile of miRNA expression in response to radiation was examined and validated by RT-PCR. miR-142-3p inhibited the expression of CD133 in umbilical cord blood mononuclear cells to increase radiosensitivity. CD133+HUCB-MNC cells were more radioresistant compared with CD133-HUCB-MNC cells. CD133+HUCB-MNC cells showed higher p-AKT and p-ERK levels after radiation. And miR-142-3p acted on 3'UTR of CD133 mRNA to inhibit CD133 expression. Moreover, miRNA-142-3p mimic increased radiosensitivity in CD133+HUCB-MNC cells. Our results elucidated a novel regulation pathway in hematopoietic stem cells and suggested a potential therapeutic approach for blood system diseases therapy.

Alteration of microRNA profiles by a novel inhibitor of human La protein in HBV-transformed human hepatoma cells

A pyrazolopyridine HBSC11 was previously identified as a novel inhibitor of human La protein with anti‐hepatitis B virus (HBV) activity. However, the underlying mechanism(s) of HBV inhibition by HBSC11 remains unclear. This study aimed to examine the regulation of microRNA (miRNA) by HBSC11 in HBV‐transformed human hepatoma HepG2.2.15 cells using microarray and quantitative real‐time PCR. Target genes of the differentially expressed miRNAs were predicted and subjected to bioinformatics analysis. Results showed that HBSC11 significantly upregulated the expression of miR‐3912‐5p, miR‐6793‐5p, and miR‐7159‐5p in HepG2.2.15 cells. Target genes of the three miRNAs were mainly involved in the regulation of nucleic acid‐templated transcription, negative regulation of gene expression, nucleic acid binding transcription factor activity and regulation of phosphorylation. In addition, target genes were enriched in certain regulatory pathways related to HBV infection and HBV‐associated disease progression, such as the transforming growth factor (TGF)‐β, Wnt, and p53 signaling. Our study demonstrates the involvement of miR‐3912‐5p, miR‐6793‐5p, and miR‐7159‐5p and the potential modulation of specific pathways (TGF‐β, Wnt, and p53 signaling) in HBSC11‐mediated inhibition of HBV replication. This study provides insight into the molecular mechanism of the action of HBSC11 against HBV infection and will support the development of antiviral drugs targeting La protein.

microRNAs: important regulators of stem cells

Stem cells are undifferentiated cells and have multi-lineage differentiation potential. Generally, stem cells are classified into adult stem cells, embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Stem cells have great potential in clinical therapy due to their pluripotency and self-renewal ability. microRNAs (miRNAs) are small non-coding RNAs which are evolutionarily conserved and participate in the pathogenesis of many diseases, cell cycle regulation, apoptosis, aging, cell fate decisions, and different signaling pathways. Different kinds of stem cells possess distinct miRNA expression profiles. Our review summarizes the critical roles of miRNAs in stem cell reprogramming, pluripotency maintenance, and differentiation. In the future, miRNAs may greatly contribute to stem cell clinical therapy and have potential applications in regenerative medicine.