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

Modulatory effects of miRNAs in doxorubicin resistance: A mechanistic view

MicroRNAs (miRNAs) are a group of small non-coding RNAs and play an important role in controlling vital biological processes, including cell cycle control, apoptosis, metabolism, and development and differentiation, which lead to various diseases such as neurological, metabolic disorders, and cancer. Chemotherapy consider as gold treatment approaches for cancer patients. However, chemotherapeutic is one of the main challenges in cancer management. Doxorubicin (DOX) is an anti-cancer drug that interferes with the growth and spread of cancer cells. DOX is used to treat various types of cancer, including breast, nervous tissue, bladder, stomach, ovary, thyroid, lung, bone, muscle, joint and soft tissue cancers. Also recently, miRNAs have been identified as master regulators of specific genes responsible for the mechanisms that initiate chemical resistance. miRNAs have a regulatory effect on chemotherapy resistance through the regulation of apoptosis process. Also, the effect of miRNAs p53 gene as a key tumor suppressor was confirmed via studies. miRNAs can affect main biological pathways include PI3K pathway. This review aimed to present the current understanding of the mechanisms and effects of miRNAs on apoptosis, p53 and PTEN/PI3K/Akt signaling pathway related to DOX resistance.

Use of extracellular vesicle microRNA profiles in patients with acute myeloid leukemia for the identification of novel biomarkers

OBJECTIVES

This study aimed to establish clinically significant microRNA (miRNA) sets using extracellular vesicles (EVs) from bone marrow (BM) aspirates of patients with acute myelogenous leukemia (AML), and to identify the genes that interact with these EV-derived miRNAs in AML.

MATERIALS AND METHODS

BM aspirates were collected from 32 patients with AML at the time of AML diagnosis. EVs were isolated using size-exclusion chromatography. A total of 965 EV-derived miRNAs were identified in all the samples.

RESULTS

We analyzed the expression levels of these EV-derived miRNAs of the favorable (n = 10) and non-favorable (n = 22) risk groups; we identified 32 differentially expressed EV-derived miRNAs in the non-favorable risk group. The correlation of these miRNAs with risk stratification and patient survival was analyzed using the information of patients with AML from The Cancer Genome Atlas (TCGA) database. Of the miRNAs with downregulated expression in the non-favorable risk group, hsa-miR-181b and hsa-miR-143 were correlated with non-favorable risk and short overall survival. Regarding the miRNAs with upregulated expression in the non-favorable risk group, hsa-miR-188 and hsa-miR-501 were correlated with non-favorable risk and could predict poor survival. Through EV-derived miRNAs-mRNA network analysis using TCGA database, we identified 21 mRNAs that could be potential poor prognosis biomarkers.

CONCLUSIONS

Overall, our findings revealed that EV-derived miRNAs can serve as biomarkers for risk stratification and prognosis in AML. In addition, these EV-derived miRNA-based bioinformatic analyses could help efficiently identify mRNAs with biomarker potential, similar to the previous cell-based approach.

Non-coding RNAs in leukemia drug resistance: new perspectives on molecular mechanisms and signaling pathways

Like almost all cancer types, timely diagnosis is needed for leukemias to be effectively cured. Drug efflux, attenuated drug uptake, altered drug metabolism, and epigenetic alterations are just several of the key mechanisms by which drug resistance develops. All of these mechanisms are orchestrated by up- and downregulators, in which non-coding RNAs (ncRNAs) do not encode specific proteins in most cases; albeit, some of them have been found to exhibit the potential for protein-coding. Notwithstanding, ncRNAs are chiefly known for their contribution to the regulation of physiological processes, as well as the pathological ones, such as cell proliferation, apoptosis, and immune responses. Specifically, in the case of leukemia chemo-resistance, ncRNAs have been recognized to be responsible for modulating the initiation and progression of drug resistance. Herein, we comprehensively reviewed the role of ncRNAs, specifically its effect on molecular mechanisms and signaling pathways, in the development of leukemia drug resistance.

M2 Macrophage-Derived sEV Regulate Pro-Inflammatory CCR2+ Macrophage Subpopulations to Favor Post-AMI Cardiac Repair

Tissue-resident cardiac macrophage subsets mediate cardiac tissue inflammation and repair after acute myocardial infarction (AMI). CC chemokine receptor 2 (CCR2)-expressing macrophages have phenotypical similarities to M1-polarized macrophages, are pro-inflammatory, and recruit CCR2⁺ circulating monocytes to infarcted myocardium. Small extracellular vesicles (sEV) from CCR2^̶ macrophages, which phenotypically resemble M2-polarized macrophages, promote anti-inflammatory activity and cardiac repair. Here, the authors harvested M2 macrophage-derived sEV (M2_EV ) from M2-polarized bone-marrow-derived macrophages for intramyocardial injection and recapitulation of sEV-mediated anti-inflammatory activity in ischemic-reperfusion (I/R) injured hearts. Rats and pigs received sham surgery; I/R without treatment; or I/R with autologous M2_EV treatment. M2_EV rescued cardiac function and attenuated injury markers, infarct size, and scar size. M2_EV inhibited CCR2⁺ macrophage numbers, reduced monocyte-derived CCR2⁺ macrophage recruitment to infarct sites, induced M1-to-M2 macrophage switching and promoted neovascularization. Analysis of M2_EV microRNA content revealed abundant miR-181b-5p, which regulated macrophage glucose uptake, glycolysis, and mitigated mitochondrial reactive oxygen species generation. Functional blockade of miR-181b-5p is detrimental to beneficial M2_EV actions and resulted in failure to inhibit CCR2⁺ macrophage numbers and infarct size. Taken together, this investigation showed that M2_EV rescued myocardial function, improved myocardial repair, and regulated CCR2⁺ macrophages via miR-181b-5p-dependent mechanisms, indicating an option for cell-free therapy for AMI.

The Promising Role of Non-Coding RNAs as Biomarkers and Therapeutic Targets for Leukemia

Early-stage leukemia identification is crucial for effective disease management and leads to an improvement in the survival of leukemia patients. Approaches based on cutting-edge biomarkers with excellent accuracy in body liquids provide patients with the possibility of early diagnosis with high sensitivity and specificity. Non-coding RNAs have recently received a great deal of interest as possible biomarkers in leukemia due to their participation in crucial oncogenic processes such as proliferation, differentiation, invasion, apoptosis, and their availability in body fluids. Recent studies have revealed a strong correlation between leukemia and the deregulated non-coding RNAs. On this basis, these RNAs are also great therapeutic targets. Based on these advantages, we tried to review the role of non-coding RNAs in leukemia. Here, the significance of several non-coding RNA types in leukemia is highlighted, and their potential roles as diagnostic, prognostic, and therapeutic targets are covered.

Non-coding RNA-related antitumor mechanisms of marine-derived agents

In the last two decades, natural active substances have attracted great attention in developing new antitumor drugs, especially in the marine environment. A series of marine-derived compounds or derivatives with potential antitumor effects have been discovered and developed, but their mechanisms of action are not well understood. Emerging studies have found that several tumor-related signaling pathways and molecules are involved in the antitumor mechanisms of marine-derived agents, including noncoding RNAs (ncRNAs). In this review, we provide an update on the regulation of marine-derived agents associated with ncRNAs on tumor cell proliferation, apoptosis, cell cycle, invasion, migration, drug sensitivity and resistance. Herein, we also describe recent advances in marine food-derived ncRNAs as antitumor agents that modulate cross-species gene expression. A better understanding of the antitumor mechanisms of marine-derived agents mediated, regulated, or sourced by ncRNAs will provide new biomarkers or targets for potential antitumor drugs from preclinical discovery and development to clinical application.

microRNA expression in acute myeloid leukaemia: New targets for therapy?

Recent studies have shown that short non-coding RNAs, known as microRNAs (miRNAs) and their dysregulation, are implicated in the pathogenesis of acute myeloid leukaemia (AML). This is due to their role in the control of gene expression in a variety of molecular pathways. Therapies involving miRNA suppression and replacement have been developed. The normalisation of expression and the subsequent impact on AML cells have been investigated for some miRNAs, demonstrating their potential to act as therapeutic targets. Focussing on miRs with therapeutic potential, we have reviewed those that have a significant impact on the aberrant biological processes associated with AML, and crucially, impact leukaemic stem cell survival. We describe six miRNAs in preclinical trials (miR-21, miR-29b, miR-126, miR-181a, miR-223 and miR-196b) and two miRNAs that are in clinical trials (miR-29 and miR-155). However none have been used to treat AML patients and greater efforts are needed to develop miRNA therapies that could benefit AML patients in the future.

Small Non-Coding RNAs in Leukemia

In 2020, more than 60,500 people were diagnosed with leukemia in the USA, and more than 23,000 died. The incidence of leukemia is still rising, and drug resistance development is a serious concern for patients' wellbeing and survival. In the past two decades, small non-coding RNAs have been studied to evaluate their functions and possible role in cancer pathogenesis. Small non-coding RNAs are short RNA molecules involved in several cellular processes by regulating the expression of genes. An increasing body of evidence collected by many independent studies shows that the expression of these molecules is tissue specific, and that their dysregulation alters the expression of genes involved in tumor development, progression and drug response. Indeed, small non-coding RNAs play a pivotal role in the onset, staging, relapse and drug response of hematological malignancies and cancers in general. These findings strongly suggest that small non-coding RNAs could function as biomarkers and possible targets for therapy. Thus, in this review, we summarize the regulatory mechanisms of small non-coding RNA expression in different types of leukemia and assess their potential clinical implications.

MicroRNA-181b Inhibits Inflammatory Response and Reduces Myocardial Injury in Sepsis by Downregulating HMGB1

MicroRNAs (miRNAs) are short endogenous noncoding RNAs regulating protein translation. However, the specific mechanism by which miR-181b influences sepsis via high-mobility group box-1 protein (HMGB1) still remains unknown. Thus, the aim of this study is to investigate the mechanism of miR-181b in regulating inflammatory response in sepsis-induced myocardial injury through targeting high-mobility group box-1 protein (HMGB1). Through cecal ligation and puncture (CLP), the rat model of sepsis was established. Then, the effect of altered expression of miR-181b and HMGB1 on cardiomyocytes was investigated. The positive expression rate of HMGB1, concentration of inflammatory factors, and serum myocardial enzyme of myocardial tissues were determined. Besides, the binding site between miR-181b and HMGB1 was determined by bioinformatics information and dual-luciferase reporter gene assay. The expression of related genes in cells of each group was determined by RT-qPCR and western blot analysis, and the apoptosis rate of transfected cells in each group was determined by TUNEL assay. HMGB1 expression and inflammatory factors were significantly increased in myocardial tissue of rats with sepsis. Cell morphology and the infiltration of inflammatory cells were significantly improved by overexpression of miR-181b. miR-181b directly targeted HMGB1, and downregulation of HMGB1 reduced inflammatory factors and myocardial injury and inhibited cardiomyocyte apoptosis in sepsis. This present study suggests that miR-181b decreased inflammatory factors and reduced myocardial injury in sepsis through downregulation of HMGB1. Thus, a better understanding of this process may aid in the development of novel therapeutic agents in sepsis.

Circadian rhythm genes in cancer: insight into their functions and regulation involving noncoding RNAs

The 24-h circadian rhythm handles a wide variety of physiological needs. Clock genes, in coordination with other tissue-specific factors regulate various processes and often turns responsible for the pathological conditions when altered. Cancer is one such disease where the clock genes have been shown to contribute at multiple levels modulating key hallmarks of cancer. Most importantly, adding to this complication, noncoding RNAs (ncRNAs) have emerged as one of the major post-transcriptional regulators of gene expression and many recent studies have indicated about involvement of microRNAs or long noncoding RNAs in the process. In this review, we have described how do circadian pathway genes participated in oncogenesis and also updated the latest status of ncRNA involvement. We also try to address the existing gaps to have a more comprehensive understanding of the phenomenon in future.Abbreviations: HIFs: hypoxia-inducible factors; VEGF: Vascular endothelial growth factor; Mdm2: Mouse double minute 2 homolog; ATM: Ataxia telangiectasia mutated; Chk2: Checkpoint kinase 2; Bcl-Xl: B-cell lymphoma-extra-large; Bcl-2: B-cell lymphoma 2; DGCR8: DiGeorge syndrome chromosomal region 8; PPAR-γ: Peroxisome proliferator-activated receptor gamma.

Damage-Associated Molecular Patterns Modulation by microRNA: Relevance on Immunogenic Cell Death and Cancer Treatment Outcome

Simple Summary

Inside the cell, damage-associated molecular pattern molecules (DAMPs) play several physiological functions, but when they are released or translocated to the extracellular space, they gain additional immunogenic roles. Thus, DAMPs are considered key hallmarks of immunogenic cell death (ICD) in cancer, a functionally unique regulated form of stress-mediated cell death that activates the immune system response against tumor cells. Several epigenetic modulators of DAMPs have been reported. In this review, we aimed to provide an overview of the effects of microRNAs (miRNAs) on the expression of DAMPs and the putative link between miRNA, DAMPs, and cell death, focused on ICD. Overall, we propose that miRNAs, by targeting DAMPs, play critical roles in the regulation of both cell death and immune-associated mechanisms in cancer, while evidence of their potential involvement in ICD is limited. Finally, we discuss emerging data regarding the impact of miRNAs’ modulation on cancer treatment outcome.

Abstract

Immunogenic cell death (ICD) in cancer is a functionally unique regulated form of stress-mediated cell death that activates both the innate and adaptive immune response against tumor cells. ICD makes dying cancer cells immunogenic by improving both antigenicity and adjuvanticity. The latter relies on the spatiotemporally coordinated release or exposure of danger signals (DAMPs) that drive robust antigen-presenting cell activation. The expression of DAMPs is often constitutive in tumor cells, but it is the initiating stressor, called ICD-inducer, which finally triggers the intracellular response that determines the kinetics and intensity of their release. However, the contribution of cell-autonomous features, such as the epigenetic background, to the development of ICD has not been addressed in sufficient depth. In this context, it has been revealed that several microRNAs (miRNAs), besides acting as tumor promoters or suppressors, can control the ICD-associated exposure of some DAMPs and their basal expression in cancer. Here, we provide a general overview of the dysregulation of cancer-associated miRNAs whose targets are DAMPs, through which new molecular mediators that underlie the immunogenicity of ICD were identified. The current status of miRNA-targeted therapeutics combined with ICD inducers is discussed. A solid comprehension of these processes will provide a framework to evaluate miRNA targets for cancer immunotherapy.

Inhibitors of Chemoresistance Pathways in Combination with Ara-C to Overcome Multidrug Resistance in AML. A Mini Review

Acute myeloid leukemia (AML), the most common type of leukemia in older adults, is a heterogeneous disease that originates from the clonal expansion of undifferentiated hematopoietic progenitor cells. These cells present a remarkable variety of genes and proteins with altered expression and function. Despite significant advances in understanding the molecular panorama of AML and the development of therapies that target mutations, survival has not improved significantly, and the therapy standard is still based on highly toxic chemotherapy, which includes cytarabine (Ara-C) and allogeneic hematopoietic cell transplantation. Approximately 60% of AML patients respond favorably to these treatments and go into complete remission; however, most eventually relapse, develop refractory disease or chemoresistance, and do not survive for more than five years. Therefore, drug resistance that initially occurs in leukemic cells (primary resistance) or that develops during or after treatment (acquired resistance) has become the main obstacle to AML treatment. In this work, the main molecules responsible for generating chemoresistance to Ara-C in AML are discussed, as well as some of the newer strategies to overcome it, such as the inclusion of molecules that can induce synergistic cytotoxicity with Ara-C (MNKI-8e, emodin, metformin and niclosamide), subtoxic concentrations of chemotherapy (PD0332991), and potently antineoplastic treatments that do not damage nonmalignant cells (heteronemin or hydroxyurea + azidothymidine).

Mitochondrial metabolism as a target for acute myeloid leukemia treatment

Acute myeloid leukemias (AML) are a group of aggressive hematologic malignancies resulting from acquired genetic mutations in hematopoietic stem cells that affect patients of all ages. Despite decades of research, standard chemotherapy still remains ineffective for some AML subtypes and is often inappropriate for older patients or those with comorbidities. Recently, a number of studies have identified unique mitochondrial alterations that lead to metabolic vulnerabilities in AML cells that may present viable treatment targets. These include mtDNA, dependency on oxidative phosphorylation, mitochondrial metabolism, and pro-survival signaling, as well as reactive oxygen species generation and mitochondrial dynamics. Moreover, some mitochondria-targeting chemotherapeutics and their combinations with other compounds have been FDA-approved for AML treatment. Here, we review recent studies that illuminate the effects of drugs and synergistic drug combinations that target diverse biomolecules and metabolic pathways related to mitochondria and their promise in experimental studies, clinical trials, and existing chemotherapeutic regimens.

miRNAs mediated drug resistance in hematological malignancies

Despite improvements in the therapeutic approaches for hematological malignancies in the last decades, refractory disease still occurs, and cancer drug resistance still remains a major hurdle in the clinical management of these cancer patients. The investigation of this problem has been extensive and different mechanism and molecules have been associated with drug resistance. MicroRNAs (miRNAs) have been described as having an important action in the emergence of cancer, including hematological tumors, and as being major players in their progression, aggressiveness and response to treatments. Moreover, miRNAs have been strongly associated with cancer drug resistance and with the modulation of the sensitivity of cancer cells to a wide array of anticancer drugs. Furthermore, this role has also been reported for miRNAs packaged into extracellular vesicles (EVs-miRNAs), which in turn have been described as essential for the horizontal transfer of drug resistance to sensitive cells. Several studies have been suggesting the use of miRNAs as biomarkers for drug response and clinical outcome prediction, as well as promising therapeutic tools in hematological diseases. Indeed, the combination of miRNA-based therapeutic tools with conventional drugs contributes to overcome drug resistance. This review addresses the role of miRNAs in the pathogenesis of hematological malignances, namely multiple myeloma, leukemias and lymphomas, highlighting their important action (either in their cell-free circulating form or within circulating EVs) in drug resistance and their potential clinical applications.

LINC00665 promotes the progression of acute myeloid leukemia by regulating the miR-4458/DOCK1 pathway

This study aimed to explore the role of LINC00665, miR-4458 and DOCK1 and their interactions in the development of acute myeloid leukemia (AML). The relative expression of LINC00665, miR-4458 and DOCK1 in AML samples was measured using qRT-PCR, and the protein level of DOCK1 in AML cell lines was examined using western blot. CCK8, BrdU, transwell, cell adhesion, and caspase-3 activity assays were carried out to evaluate the viability, proliferation, migration, adhesion, and apoptosis of AML cells, respectively. Luciferase reporter, RIP, and RNA pull-down assays were also performed to confirm the target relationship among LINC00665, miR-4458 and DOCK1. Findings revealed that LINC00665 and DOCK1 were aberrantly overexpressed in AML tissues and that the expression of miR-4458 was low in AML tissues. Silencing LINC00665 or DOCK1 presented significant restriction to the proliferation, migration and adhesion of AML cells. Apart from that, it was found that inhibiting miR-4458 could enhance the proliferation, migration and adhesion of AML cells but suppress the apoptosis of AML cells. Experimental results also indicated that LINC00665 exerted its positive function on AML cells by sponging miR-4458 and that miR-4458 influenced the progression of AML cells by targeting DOCK1 directly. Overall, this finding not only provided a novel molecular pathway for the diagnosis and treatment of AML but also showed that LINC00665 could enhance the progression of AML by regulating the miR-4458/DOCK1 pathway.

Chronic stress promotes acute myeloid leukemia progression through HMGB1/NLRP3/IL-1β signaling pathway

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy with poor prognosis and overall survival. Clinical investigations show that chronic stress is commonly present in the course of AML and associated with adverse outcome. However, the underlying molecular mechanisms are elusive. In the present study, a chronic restraint stress mouse model was established to evaluate the effect of stress on AML. We found that mice under chronic stress exhibited significantly increased liver and spleen infiltration of leukemic cells and poorer overall survival. This was accompanied by elevated cellular NLR family pyrin domain containing 3 (NLRP3) and interleukin-1β (IL-1β) in the liver or bone marrow, and secreted IL-1β in the plasma, indicating the activation of inflammasomes under chronic restraint stress. High mobility group box 1 (HMGB1) expression was markedly increased in newly diagnosed AML patients, but reduced in complete remission AML patients. The expression level of HMGB1 was positively correlated with NLRP3 mRNA in AML patients. Knockdown of HMGB1 significantly decreased NLRP3 and IL-1β expression in AML cell lines, and secreted IL-1β in supernatant of AML cell culture, while HMGB1 stimulation caused contrary effects. These results implied that HMGB1 could be involved in the regulation of inflammasome activation in AML development. Mice model showed that chronic restraint stress-facilitated proliferation and infiltration of AML cells were largely abrogated by knocking down HMGB1. Knockdown of HMGB1 also ameliorated overall survival and remarkably neutralized NLRP3 and IL-1β expression under chronic restraint stress. These findings provide evidences that chronic stress promotes AML progression via HMGB1/NLRP3/IL-1β dependent mechanism, suggesting that HMGB1 is a potential therapeutic target for AML. KEY MESSAGES: • Chronic restraint stress promoted acute myeloid leukemia (AML) progression and mediated NLRP3 inflammasome activation in xenograft mice. • HMGB1 mediated NLRP3 inflammasome activation in AML cells. • Knockdown of HMGB1 inhibited AML progression under chronic stress in vivo.

CircCSNK1G3 up-regulates miR-181b to promote growth and metastasis via TIMP3-mediated epithelial to mesenchymal transitions in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common form of kidney cancer, with a high recurrence rate and metastasis capacity. Circular RNAs (circRNAs) have been suggested to act as the critical regulator in several diseases. This study is designed to investigate the role of circCSNK1G3 on RCC progression. We observed a highly expression of circCSNK1G3 in RCC tissues compared with normal tissues. The aberrantly circCSNK1G3 promoted the tumour growth and metastasis in RCC. In the subsequent mechanism investigation, we discovered that the tumour‐promoting effects of circCSNK1G3 were, at least partly, achieved by up‐regulating miR‐181b. Increased miR‐181b inhibits several tumour suppressor gene, including CYLD, LATS2, NDRG2 and TIMP3. Furthermore, the decreased TIMP3 leads to the enhanced epithelial to mesenchymal transition (EMT) process, thus promoting the cancer metastasis. In conclusion, we identified the oncogenic role of circCSNK1G3 in RCC progression and demonstrated the regulatory role of circCSNK1G3 induced miR‐181b expression, which leads to TIMP3‐mediated EMT process, thus resulting in tumour growth and metastasis in RCC. This study reveals the promise of circCSNK1G3 to be developed as a potential diagnostic and prognostic biomarker in the clinic. And the roles of circCSNK1G3 in cancer research deserve further investigation.

The renoprotective effect of curcumin against cisplatin-induced acute kidney injury in mice: involvement of miR-181a/PTEN axis

Background: Nephrotoxicity, especially acute kidney injury (AKI), is the main dose-limiting toxicity of cisplatin. Although recent studies showed that curcumin prevented cisplatin-induced AKI effectively, further studies to understand the mechanism are required.Methods: We established an AKI mouse model. Male C57BL/6 mice were assigned to three groups: saline group (control), cisplatin group (CP), and curcumin + cisplatin group (CP + Cur). The CP group received a single intraperitoneal (i.p.) injection of cisplatin, while the control group received saline. The CP + Cur group received i.p. curcumin three days before cisplatin injection and curcumin administered for another three days until the day before euthanization. Renal injury was assessed by serological and histological analysis. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the phosphatase and tensin homolog (PTEN), and microRNA (miR)-181a expression in the renal tissues. Bioinformatics prediction and western blotting methods validated the targets of miR-181a in vitro.Results: Curcumin treatment alleviated cisplatin-induced nephrotoxicity as validated by the blood urea nitrogen (BUN) values, and histological analysis of kidneys. At the molecular level, curcumin treatment decreased miR-181a expression level, which was induced by cisplatin and restored the in vivo expression of PTEN, which was suppressed by cisplatin. We verified the direct regulation of PTEN by miR-181a in cultured human embryonic kidney 293T cells.Conclusions: We showed the involvement of miR-181a/PTEN axis in the renoprotective effect of curcumin against cisplatin-induced AKI, and provide new evidence on the ability of curcumin to alleviate cisplatin-induced nephrotoxicity.

Expression profiles of HMGB1 on B-CLL related leukocytes contribute to prediction of relapse

BACKGROUND

The High Mobility Group Box 1 (HMGB1) is a nuclear protein that is frequently overexpressed in hematologic diseases and might be of relevance in immunogenic cancer control thus correlating with patients' (pts.) prognosis in diseases such as acute myeloid, acute lymphatic and chronic lymphocytic leukemia.

MATERIALS AND METHODS

Expression profiles of blasts from AML (n = 21), ALL (n = 16) and of B-lymphocytes of CLL (n = 9) pts. were analyzed for surface expression of HMGB1 using flow cytometry. Expression was quantified and correlated with clinically and prognostically relevant markers.

RESULTS

Expression profiling of HMGB1 in blasts of AML and ALL subtypes did not show differences between primary vs. secondary disease development and gender related differences. In ALL pts. however, age groups at initial diagnosis between ≥20 vs. <20 years were compared and showed significant differences (≥20 vs. <20 years; 89% vs. 49%, p  <0.05) with higher expression in higher age. In AML and CLL these differences were not visible. To evaluate the prognostic significance of HMGB1 expression, expression quantity was correlated with established and prognostic classification systems (in AML ELN, in ALL GMALL) and probability to relapse. No significant correlation was seen in these entities. However, when AML pts. were analyzed for remission rates after first anthracycline based induction therapy, in those who did not experience a complete remission significantly enhanced HMGB1 surface expression was seen (98 vs. 94%; p < 0.05; n = 20). Furthermore, for CLL it was shown that higher HMGB1 expression was found in pretreated patients with relapsed or/and refractory disease (1 vs. more relapses; 94 vs. 98%; p  <0.05; n = 9).

CONCLUSION

HMGB1 is frequently expressed in hematologic malignancies. In this study it was shown that HMGB1 surface expression on AML blasts can be used as predictors for treatment response. In CLL it may be a marker for advanced disease. In order to implement this marker in FACS routine it could be a useful and practical tool for prognostic assessment and treatment planning.

Expression and role of nuclear receptor-interacting protein 1 (NRIP1) in stomach adenocarcinoma

Background

Nuclear receptor-interacting protein 1 (NRIP1), also named NR140, has been observed differentially express in multiple cancers, but the expression levels and the prognostic role of NRIP1 in stomach adenocarcinoma (STAD) remain unclear.

Methods

We used the Gene Expression Profiling Interactive Analysis (GEPIA) to analyze the NRIP1 expression levels in STAD, subgroups analysis of expression of NRIP1 via the UALCAN dataset. Further, cBioPortal was used to investigate the aberration type, co-mutations status, and located mutation of NRIP1. Correlated genes, and kinases, microRNA (miRNA), and transcription factor (TF) targets were identified using LinkedOmics. The Kaplan-Meier (K-M) plotter was used to analyze the prognosis of NRIP1 and the significantly correlated genes in STAD. Then, the tumor immune estimation resource (Timer) was used to explore the relation between NRIP1 and the immune cell infiltration, and the role of immune cells in STAD. The Human Protein Atlas (HPA) was used to confirm the NRIP1 protein express in STAD stomach tissue and normal stomach tissue.

Results

NRIP1 significantly overexpress in STAD, and the NRIP1 expression levels were impacted by clinical features. Overexpression of NRIP1 indicated the poor prognosis of STAD. Functional enrichment analysis showed the NRIP1 mainly enriched in immune response-regulating signaling pathway, cell-substrate adhesion, mRNA processing, and pathway in cancer. Overexpression USP25, SNYJ1 indicated the poor outcome of STAD, but the overexpression of BACH1 indicated protective biomarker. MIR-331 and MIR-132 have important role in STAD. Further, NRIP1 had a significant relation with immune infiltrates and other defined genes that significantly impact immune infiltrates. Immunohistochemical showed NRIP1 protein was higher in STAD than normal sample.

Conclusions

In this study, we revealed that overexpression of NRIP1 in the STAD sample compared to normal samples, NRIP1 significantly associated with macrophage. The high expression levels of NRIP1 and more macrophage infiltration led to poor prognosis of STAD.

Autophagy-mediating microRNAs in cancer chemoresistance

Chemoresistance is a complex phenomenon responsible for failure in response to chemotherapy agents and more than 90% of deaths in cancer patients. MicroRNAs (miRNAs), as a subgroup of non-coding RNAs with lengths between 21 and 25 nucleotides, are involved in various cancer processes like chemoresistance via interacting with their target mRNAs and suppressing their expression. Autophagy is a greatly conserved procedure involving the lysosomal degradation of cytoplasmic contents and organelles to deal with environmental stresses like hypoxia and starvation. Autophagy contributes to response to chemotherapy agents: autophagy can act as a protective mechanism for mediating the resistance in response to chemotherapy or can induce autophagic cell death and mediate the sensitivity to chemotherapy. On the other hand, one of the processes targeted by microRNAs in the regulation of chemoresistance is autophagy. Hence, we studied the literatures on chemoresistance mechanisms, the miRNAs' role in cancer, and the miRNAs' role in chemoresistance by modulating autophagy. Graphical Abstract.

High mobility group box 1 (HMGB1): a pivotal regulator of hematopoietic malignancies

High mobility group box 1 (HMGB1) is a nonhistone chromatin-associated protein that has been widely reported to play a pivotal role in the pathogenesis of hematopoietic malignancies. As a representative damage-associated molecular pattern (DAMP), HMGB1 normally exists inside cells but can be secreted into the extracellular environment through passive or active release. Extracellular HMGB1 binds with several different receptors and interactors to mediate the proliferation, differentiation, mobilization, and senescence of hematopoietic stem cells (HSCs). HMGB1 is also involved in the formation of the inflammatory bone marrow (BM) microenvironment by activating proinflammatory signaling pathways. Moreover, HMGB1-dependent autophagy induces chemotherapy resistance in leukemia and multiple myeloma. In this review, we systematically summarize the emerging roles of HMGB1 in carcinogenesis, progression, prognosis, and potential clinical applications in different hematopoietic malignancies. In summary, targeting the regulation of HMGB1 activity in HSCs and the BM microenvironment is highly beneficial in the diagnosis and treatment of various hematopoietic malignancies.

Noncoding RNAs: the shot callers in tumor immune escape

Immunotherapy, designed to exploit the functions of the host immune system against tumors, has shown considerable potential against several malignancies. However, the utility of immunotherapy is heavily limited due to the low response rate and various side effects in the clinical setting. Immune escape of tumor cells may be a critical reason for such low response rates. Noncoding RNAs (ncRNAs) have been identified as key regulatory factors in tumors and the immune system. Consequently, ncRNAs show promise as targets to improve the efficacy of immunotherapy in tumors. However, the relationship between ncRNAs and tumor immune escape (TIE) has not yet been comprehensively summarized. In this review, we provide a detailed account of the current knowledge on ncRNAs associated with TIE and their potential roles in tumor growth and survival mechanisms. This review bridges the gap between ncRNAs and TIE and broadens our understanding of their relationship, providing new insights and strategies to improve immunotherapy response rates by specifically targeting the ncRNAs involved in TIE.

microRNA-181 serves as a dual-role regulator in the development of human cancers

MicroRNAs (miRNAs) as the regulatory short noncoding RNAs are involved in a wide array of cellular and molecular processes. They negatively regulate gene expression and their dysfunction is correlated with cancer development through modulation of multiple signaling pathways. Therefore, these molecules could be considered as novel biomarkers and therapeutic targets for more effective management of human cancers. Recent studies have demonstrated that the miR-181 family is dysregulated in various tumor tissues and plays a pivotal role in carcinogenesis. They have been shown to act as oncomirs or tumor suppressors considering their mRNA targets and to be involved in cell proliferation, apoptosis, autophagy, angiogenesis and drug resistance. Additionally, these miRNAs have been demonstrated to exert their regulatory effects through modulating multiple signaling pathways including PI3K/AKT, MAPK, TGF-b, Wnt, NF-κB, Notch pathways. Given that, in this review, we briefly summarise the recent studies that have focused on the roles of miRNA-181 family as the multifunctional miRNAs in tumorigenesis and cancer development. These miRNAs may serve as diagnostic and prognostic biomarkers or therapeutic targets in human cancer gene therapy.

LncRNA MEG3 contributes to drug resistance in acute myeloid leukemia by positively regulating ALG9 through sponging miR-155

INTRODUCTION

The development of drug resistance is the main obstacle for successful treatment in acute myeloid leukemia (AML). Noncoding RNAs have been implicated in biological function in AML drug resistance. Aberrant protein glycosylation is associated with AML progression. The aim of the study was to explore the potential regulatory mechanism of lncRNA MEG3/miR-155/ALG9 axis in drug resistance of AML.

METHODS

QRT-PCR and Western blot were used for comparison analyses of ALG9, MEG3, and miR-155 levels. CCK-8 and colony formation assays were determined for drug sensitivity and proliferative capability of AML cells. Luciferase reporter assay was used to confirm the targets of miR-155.

RESULTS

The mannosyltransferase ALG9 and MEG3 was downregulated in peripheral blood mononuclear cells (PBMCs) of M5/multidrug resistance (MDR) AML patients and adriamycin (ADR)-resistant AML cell lines, which determined a positive correlation in AML patients. Low expression of ALG9 and MEG3 predicted poor prognosis of AML patients. The altered level of ALG9 was found corresponding to the drug-resistant phenotype and sphere formation of AML cells. MiR-155 was overexpressed in M5/MDR patients and ADR-resistant AML cells, as well as inversely correlated to ALG9 expression. MEG3 was a direct target of miR-155 and could sponge miR-155 in AML cells. MEG3 interacted with miR-155 to regulate ALG9 expression, which reversed the effects of ALG9 regulation on proliferation and drug resistance in AML cells.

CONCLUSION

MEG3 sponged miR-155 by competing endogenous RNA (ceRNA) mechanism, which further modulated ALG9 expression and AML procession, providing a novel therapeutic target for AML chemoresistance.

Role of non-coding RNA networks in leukemia progression, metastasis and drug resistance

Early-stage detection of leukemia is a critical determinant for successful treatment of the disease and can increase the survival rate of leukemia patients. The factors limiting the current screening approaches to leukemia include low sensitivity and specificity, high costs, and a low participation rate. An approach based on novel and innovative biomarkers with high accuracy from peripheral blood offers a comfortable and appealing alternative to patients, potentially leading to a higher participation rate.

Recently, non-coding RNAs due to their involvement in vital oncogenic processes such as differentiation, proliferation, migration, angiogenesis and apoptosis have attracted much attention as potential diagnostic and prognostic biomarkers in leukemia. Emerging lines of evidence have shown that the mutational spectrum and dysregulated expression of non-coding RNA genes are closely associated with the development and progression of various cancers, including leukemia. In this review, we highlight the expression and functional roles of different types of non-coding RNAs in leukemia and discuss their potential clinical applications as diagnostic or prognostic biomarkers and therapeutic targets.

MN1, FOXP1 and hsa-miR-181a-5p as prognostic markers in acute myeloid leukemia patients treated with intensive induction chemotherapy and autologous stem cell transplantation

BACKGROUND

The meningioma-1 (MN1) gene is expressed in hematopoietic CD34+ cells and down-regulated during myeloid differentiation. MN1 overexpression has been linked to shorter overall and disease free survival in AML patients treated with intensive induction chemotherapy. MN1 overexpression may still be an adverse prognostic marker in AML patients treated with autologous stem cell transplant (auto-SCT) after intensive induction chemotherapy.

METHODS

We retrospectively analysed 54 peripheral blood mononuclear cell (PBMC) samples of AML patients who received auto-SCT at remission (CR1) after intensive induction chemotherapy. MN1 and putative MN1-associated mRNAs, as well as MN1-associated micro-RNAs were assessed at diagnosis in peripheral blood mononuclear cells using Taqman gene expression assays.

RESULTS

AML patients with elevated MN1 or FoxP1 gene expression at diagnosis had a significantly shorter progression-free and overall survival after intensive induction chemo-therapy and auto-SCT. The presence of the favourable risk NPM1 mutation associated with reduced MN1 gene expression. In contrast to MN1 and FOXP1, elevated expression of the putative tumor suppressive micro-RNA hsa-miR-181a-5p was predictive for positive outcome. Correlation analysis of MN1 with myeloid gene expression levels revealed association of MN1 and BMI-1, CD34, FOXP1 and MDM2 expression. Analysis of non-coding RNAs revealed an inverse correlation of MN1 with hsa-miR-20a-5p and hsa-miR-181b-5p expression.

CONCLUSIONS

MN1, FOXP1 and hsa-miR-181a-5p are prognostic markers in AML patients treated with intensive induction chemotherapy and auto-SCT. While MDM2 is a validated therapeutic target, the transcription factors MN1 and FOXP1, and the chromatin modulator BMI-1 are potential therapeutic targets in the treatment of AML. The tumor suppressor hsa-miR-181a-5p may be a candidate miRNA mimic for therapeutic use.

Advances in the discovery of microRNA-based anticancer therapeutics: latest tools and developments

Introduction: MicroRNAs (miRNAs) are small endogenous non-coding RNAs that repress the expression of their target genes by reducing mRNA stability and/or inhibiting translation. miRNAs are known to be aberrantly regulated in cancers. Modulators of miRNA (mimics and antagonists) have emerged as novel therapeutic tools for cancer treatment.Areas covered: This review summarizes the various strategies that have been applied to correct the dysregulated miRNA in cancer cells. The authors also discuss the recent advances in the technical development and preclinical/clinical evaluation of miRNA-based therapeutic agents.Expert opinion: Application of miRNA-based therapeutics for cancer treatment is appealing because they are able to modulate multiple dysregulated genes and/or signaling pathways in cancer cells. Major obstacles hindering their clinical development include drug delivery, off-target effects, efficacious dose determination, and safety. Tumor site-specific delivery of novel miRNA therapeutics may help to minimize off-target effects and toxicity. Combination of miRNA therapeutics with other anticancer treatment modalities could provide a synergistic effect, thus allowing the use of lower dose, minimizing off-target effects, and improving the overall safety profile in cancer patients. It is critical to identify individual miRNAs with cancer type-specific and context-specific regulation of oncogenes and tumor-suppressor genes in order to facilitate the precise use of miRNA anticancer therapeutics.

Altered expression of miR-181 affects cell fate and targets drug resistance-related mechanisms

MicroRNAs (miRNAs) are non-coding transcripts which regulate genetic and epigenetic events by interfering with mRNA translation. miRNAs are involved in regulation of cell fate due to their ability of interfering with physiological or pathological processes. In this review paper, we evaluate the role of miR-181 family members as prognostic or diagnostic markers or therapeutic targets in malignant pathologies in connection with the main hallmarks of cancer that are modulated by the family. Also, we take over the dual role of this family in dependency with the tumour suppressor and oncogenic features presented in cell and cancer type specific manner. Restoration of the altered expression levels contributes to the activation of cell death pathways or to a reduction in the invasion and migration mechanism; moreover, the mechanism of drug resistance is also modulated by miR-181 sequences with important applications in therapeutic strategies for malignant cells sensitisation. Overall, the main miR-181 family regulatory mechanisms are presented in a cancer specific context, emphasizing the possible clinical application of this family in terms of novel diagnosis and therapy approaches.

MicroRNAs in cancer cell death pathways: Apoptosis and necroptosis

To protect tissues and the organism from disease, potentially harmful cells are removed through programmed cell death processes, including apoptosis and necroptosis. These types of cell death are critically controlled by microRNAs (miRNAs). MiRNAs are short RNA molecules that target and inhibit expression of many cellular regulators, including those controlling programmed cell death via the intrinsic (Bcl-2 and Mcl-1), extrinsic (TRAIL and Fas), p53-and endoplasmic reticulum (ER) stress-induced apoptotic pathways, as well as the necroptosis cell death pathway. In this review, we discuss the current knowledge of apoptosis and necroptosis pathways and how these are impaired in cancer cells. We focus on how miRNAs disrupt apoptosis and necroptosis, thereby critically contributing to malignancy. Understanding which and how miRNAs and their targets affect cell death pathways could open up novel therapeutic opportunities for cancer patients. Indeed, restoration of pro-apoptotic tumor suppressor miRNAs (apoptomiRs) or inhibition of oncogenic miRNAs (oncomiRs) represent strategies that are currently being trialed or are already applied as miRNA-based cancer therapies. Therefore, better understanding the cancer type-specific expression of apoptomiRs and oncomiRs and their underlying mechanisms in cell death pathways will not only advance our knowledge, but also continue to provide new opportunities to treat cancer.

MicroRNAs and response to therapy in leukemia

A variety of epigenetic factors involved in leukemia pathogenesis. Among various epigenetic factors, microRNAs (miRNAs) have emerged as important players, which affect a sequence of cellular and molecular signaling pathways. Leukemia is known as progressive cancer, which is related to many health problems in the world. It has been shown that the destruction of the blood-forming organs could lead to abnormal effects on the proliferation and development of leukocytes and their precursors. Despite many attempts for approved effective and powerful therapies for patients with leukemia, finding and developing new therapeutic approaches are required. One of the important aspects of leukemia therapy, identification of underlying cellular and molecular mechanisms involved in the pathogenesis of leukemia. Several miRNAs (ie, miR-103, miR-101, mit-7, let-7i, miR-424, miR-27a, and miR-29c) and play major roles in response to therapy in patients with leukemia. miRNAs exert their effects by targeting a variety of targets, which are associated with response to therapy in patients with leukemia. It seems that more understanding about the roles of miRNAs in response to therapy in patients with leukemia could contribute to better treatment of patients with leukemia. Here, for the first time, we summarized various miRNAs, which are involved in response to therapy in the treatment patients with leukemia.

Overexpression of miR-758 inhibited proliferation, migration, invasion, and promoted apoptosis of non-small cell lung cancer cells by negatively regulating HMGB

Non-small cell lung cancer (NSCLC) is one of the most fatal types of cancer with significant mortality and morbidity worldwide. MicroRNAs (miRs) have been confirmed to have positive functions in NSCLC. In the present study, we try to explore the role of miR-758 in proliferation, migration, invasion, and apoptosis of NSCLC cells by regulating high-mobility group box (HMGB) 3 (HMGB3.) NSCLC and adjacent tissues were collected. Reverse transcription quantitative PCR (RT-qPCR) was employed to detect expression of miR-758 and HMGB3 in NSCLC and adjacent tissues, in BEAS-2B cells and NSCLC cell lines. The targetted relationship between miR-758 and HMGB3 was identified by dual luciferase reporter gene assay. The effects of miR-758 on proliferation, migration, invasion, cell cycle, and apoptosis of A549 cells. MiR-758 expression was lower in NSCLC tissues, which was opposite to HMGB3 expression. The results also demonstrated that miR-758 can target HMGB3. The cells transfected with miR-758 mimic had decreased HMGB3 expression, proliferation, migration, and invasion, with more arrested cells in G₁ phase and increased apoptosis. Our results supported that the overexpression of miR-758 inhibits proliferation, migration, and invasion, and promotes apoptosis of NSCLC cells by negative regulating HMGB2. The present study may provide a novel target for NSCLC treatment.

microRNA-181b suppresses the metastasis of lung cancer cells by targeting sex determining region Y-related high mobility group-box 6 (Sox6)

BACKGROUND

The aim of the study was to measure the expression of microRNA (miR)-181b in patients with lung cancer, investigate its biological function and elucidate the underlying mechanisms associated with the development of lung cancer.

METHODS

miR-181b expression in tissues was measured via RT-qPCR. After A549 cells were transfected with miR-181b mimic or si-Sox6, the proliferation, migration and cell cycle distribution of A549 were evaluated using cell counting kit-8 assay, transwell assay and flow cytometry. The levels of cell cycle-related proteins and Sox6 were analyzed by western blotting. Gene targets of miR-181b were predicted via bioinformatics analysis and verified using a dual-luciferase reporter gene assay.

RESULTS

Expression of miR-181b was significantly downregulated in lung cancer tissues (P < 0.05), and was inversely correlated with the degree of cell differentiation and clinical stages of lung cancer (both P < 0.05). Additionally, the expression of miR-181b was significantly lower in adenocarcinoma compared with squamous cell carcinoma in the lungs (P < 0.05). Overexpression of miR-181b significantly decreased the protein level of Sox6 and significantly suppressed the cell proliferation and metastasis (both P < 0.05); this effect was also observed in A549 cells transfected with si-Sox6. The luciferase activity of a Sox6 3'-untranslated region-based reporter construct was significantly lower when transfected with miR-181b (P < 0.05), which suggests that Sox6 is a direct target of miR-181b.

CONCLUSION

The results of the present study suggest that miR-181b may function as a tumor inhibitor in the development of lung cancer via targeting Sox6 to decrease the proliferation and metastasis of lung cancer cells.

OncomiR or antioncomiR: Role of miRNAs in Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) is a hematopoietic progenitor/stem cell disorder in which neoplastic myeloblasts are stopped at an immature stage of differentiation and lost the normal ability of proliferation and apoptosis. MicroRNAs (miRNAs) are small noncoding, single-stranded RNA molecules that can mediate the expression of target genes. While miRNAs mean to contribute the developments of normal functions, abnormal expression of miRNAs and regulations on their corresponding targets have often been found in the developments of AML and described in recent years. In leukemia, miRNAs may function as regulatory molecules, acting as oncogenes or tumor suppressors. Overexpression of miRNAs can down-regulate tumor suppressors or other genes involved in cell differentiation, thereby contributing to AML formation. Similarly, miRNAs can down-regulate different proteins with oncogenic activity as tumor suppressors. We herein review the current data on miRNAs, specifically their targets and their biological function based on apoptosis in the development of AML.

Aberrant mannosylation profile and FTX/miR-342/ALG3-axis contribute to development of drug resistance in acute myeloid leukemia

Drug-resistance is a major problem in acute myeloid leukemia (AML) chemotherapy. Aberrant changes in specific N-glycans have been observed in leukemia multidrug resistance (MDR). MicroRNAs (miRNAs) and long non coding RNAs (lncRNAs) act as key players in the development of AML resistance to chemotherapy. In the present study, the N-glycan profiles of membrane proteins were analyzed from adriamycin (ADR)-resistant U937/ADR cells and sensitive line U937 cells using mass spectrometry (MS). The composition profiling of high-mannose N-glycans differed in U937/ADR and U937 cell lines. Lectin microarray showed that the strong binding of membrane proteins was observed for MAN-M and ConA lectins, which were specific for mannose. These binding were also validated by flow cytometry. Importantly, the alteration of high-mannose N-glycan was further confirmed by detecting the enzyme level of ALG family. The altered level of ALG3 was found corresponding to the drug-resistant phenotype of AML cell lines both in vitro and in vivo. Mechanistically, miR-342 was found to be dysregulated and inversely correlated to ALG3 expression, targeting its 3'-UTR. LncRNA FTX was a direct target of miR-342 and positively modulated ALG3 expression by competitively binding miR-342 in AML cell lines. Functionally, we found that FTX directly interacted with miR-342 to regulate ALG3 expression and function, including ADR-resistant cell growth and apoptosis. The observation suggested that high-mannose N-glycans and mannosyltransferase ALG3 affected drug-resistance in AML cells. FTX/miR-342/ALG3 axis could potentially be used for the targets to overcome therapeutic resistance in AML.

Decoding the Emerging Patterns Exhibited in Non-coding RNAs Characteristic of Lung Cancer with Regard to their Clinical Significance

Lung cancer continues to be the leading topic concerning global mortality rate caused by can-cer; it needs to be further investigated to reduce these dramatic unfavorable statistic data. Non-coding RNAs (ncRNAs) have been shown to be important cellular regulatory factors and the alteration of their expression levels has become correlated to extensive number of pathologies. Specifically, their expres-sion profiles are correlated with development and progression of lung cancer, generating great interest for further investigation. This review focuses on the complex role of non-coding RNAs, namely miR-NAs, piwi-interacting RNAs, small nucleolar RNAs, long non-coding RNAs and circular RNAs in the process of developing novel biomarkers for diagnostic and prognostic factors that can then be utilized for personalized therapies toward this devastating disease. To support the concept of personalized medi-cine, we will focus on the roles of miRNAs in lung cancer tumorigenesis, their use as diagnostic and prognostic biomarkers and their application for patient therapy.

miRNAs in acute myeloid leukemia

MicroRNAs (miRNAs) are small, non-coding RNAs found throughout the eukaryotes that control the expression of a number of genes involved in commitment and differentiation of hematopoietic stem cells and tumorigenesis. Widespread dysregulation of miRNAs have been found in hematological malignancies, including human acute myeloid leukemia (AML). A comprehensive understanding of the role of miRNAs within the complex regulatory networks that are disrupted in malignant AML cells is a prerequisite for the development of therapeutic strategies employing miRNA modulators. Herein, we review the roles of emerging miRNAs and the miRNAs regulatory networks in AML pathogenesis, prognosis, and miRNA-directed therapies.

High mobility group box 1 (HMGB1) acts as an "alarmin" to promote acute myeloid leukaemia progression

High mobility group box 1 (HMGB1) is a non-histone protein localised in the cell nucleus, where it interacts with DNA and promotes nuclear transcription events. HMGB1 levels are elevated during acute myeloid leukaemia (AML) progression followed by participation of this protein in triggering signalling events in target cells as a pro-inflammatory stimulus. This mechanism was hypothesised to be employed as a survival pathway by malignant blood cells and our aims were therefore to test this hypothesis experimentally. Here we report that HMGB1 triggers the release of tumour necrosis factor alpha (TNF-α) by primary human AML cells. TNF-α induces interleukin 1 beta (IL-1β) production by healthy leukocytes, leading to IL-1β-induced secretion of stem cell factor (SCF) by competent cells (for example endothelial cells). These results were verified in mouse bone marrow and primary human AML blood plasma samples. In addition, HMGB1 was found to induce secretion of angiogenic vascular endothelial growth factor (VEGF) and this process was dependent on the immune receptor Tim-3. We therefore conclude that HMGB1 is critical for AML progression as a ligand of Tim-3 and other immune receptors thus supporting survival/proliferation of AML cells and possibly the process of angiogenesis.

Upregulation of miR-181c inhibits chemoresistance by targeting ST8SIA4 in chronic myelocytic leukemia

Chemotherapy resistance frequently drives tumor progression. Increased expression of ST8SIA4 has been reported in diverse carcinomas and highly correlates with leukemia multidrug resistance (MDR). MicroRNAs (miRNA) are widely recognized as key players in cancer progression and drug resistance. Here, to explore whether miRNA modulates the sensitivity of chronic myelocytic leukemia (CML) to chemotherapeutic agents and regulates ST8SIA4 expression, we analyzed the complete miRNA expression profile and found a subset of miRNAs specifically dysregulated in adriamycin-resistant CML cell line K562/ADR and its parent cell line K562. Compared with three pairs of CML cell lines and 38 clinical samples of peripheral blood mononuclear cells (PBMC) of CML patients, miR-181c expression was down-regulated in drug-resistant cell lines and CML/MDR samples. Altered expression levels of miR-181c influenced the MDR phenotypes of K562 and K562/ADR. Reporter-gene assay showed that miR-181c directly targeted and inhibited the ST8SIA4 expression, as well as miR-181c was inversely correlated with the levels of ST8SIA4 expression in CML cell lines and samples. Moreover, ST8SIA4 could reverse the effect of miR-181c on drug resistance in K562 and K562/ADR cells in vitro. Upregulation of miR-181c sensitized K562/ADR cells to adriamycin in vivo through directly suppressing ST8SIA4 expression. Further investigation showed that miR-181c mediated the activity of phosphoinositide-3 kinase (PI3K)/AKT signal pathway, and inhibition of PI3K/Akt in K562 cells counteracted miR-181c-mediated MDR phenotype. These data revealed an important role for miR-181c in the regulation of chemoresistance in CML, and suggested the potential application of miR-181c in drug resistance treatment.

MicroRNAs as New Biomarkers for Diagnosis and Prognosis, and as Potential Therapeutic Targets in Acute Myeloid Leukemia

Acute myeloid leukemias (AML) are clonal disorders of hematopoietic progenitor cells which are characterized by relevant heterogeneity in terms of phenotypic, genotypic, and clinical features. Among the genetic aberrations that control disease development there are microRNAs (miRNAs). miRNAs are small non-coding RNAs that regulate, at post-transcriptional level, translation and stability of mRNAs. It is now established that deregulated miRNA expression is a prominent feature in AML. Functional studies have shown that miRNAs play an important role in AML pathogenesis and miRNA expression signatures are associated with chemotherapy response and clinical outcome. In this review we summarized miRNA signature in AML with different cytogenetic, molecular and clinical characteristics. Moreover, we reviewed the miRNA regulatory network in AML pathogenesis and we discussed the potential use of cellular and circulating miRNAs as biomarkers for diagnosis and prognosis and as therapeutic targets.

MicroRNA: an important regulator in acute myeloid leukemia

MicroRNAs (miRNAs) are a general class of endogenous non-coding RNAs with a length of 22 nucleotides, widely existing in diverse species and playing important roles in malignancies initiation and progression. MiRNAs are essential to many in vivo biological processes such as cell proliferation, apoptosis, immune response, and tumorigenesis. Significant progress till date has been made in understanding the roles of microRNAs in normal hematopoiesis and hematopoietic malignant diseases. In this review, we summarize the particular signatures of microRNAs in acute myeloid leukemia (AML) patients with specific karyotype and the clinical significance of microRNAs in early diagnosis and treatment. MicroRNAs hypermethylation was also proved to correlate with the pathogenesis of AML. However, the target genes and exact pathways of microRNAs participating in these processes are still unknown and more efforts need to be made in the near future.

MicroRNAs and acute myeloid leukemia: therapeutic implications and emerging concepts

Acute myeloid leukemia (AML) is a deadly hematologic malignancy characterized by the uncontrolled growth of immature myeloid cells. Over the past several decades, we have learned a tremendous amount regarding the genetic aberrations that govern disease development in AML. Among these are genes that encode noncoding RNAs, including the microRNA (miRNA) family. miRNAs are evolutionarily conserved small noncoding RNAs that display important physiological effects through their posttranscriptional regulation of messenger RNA targets. Over the past decade, studies have identified miRNAs as playing a role in nearly all aspects of AML disease development, including cellular proliferation, survival, and differentiation. These observations have led to the study of miRNAs as biomarkers of disease, and efforts to therapeutically manipulate miRNAs to improve disease outcome in AML are ongoing. Although much has been learned regarding the importance of miRNAs in AML disease initiation and progression, there are many unanswered questions and emerging facets of miRNA biology that add complexity to their roles in AML. Moving forward, answers to these questions will provide a greater level of understanding of miRNA biology and critical insights into the many translational applications for these small regulatory RNAs in AML.

MicroRNA-181a and its target Smad 7 as potential biomarkers for tracking child acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common pediatric hematologic tumor. MiR-181a was expected to have a role in the development of hematological malignancies; it might act as tumor suppressor or oncogene. Smad7 was selected as miR-181a target pair. It is a negative regulator for the TGF-β1 signaling pathway. In this study, relative expression levels of miR-181a by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), both Smad 7 and TGF-β1 proteins levels by enzyme linked immunosorbent assay (ELISA) were all measured in serum of 60 child, 30 with ALL and 30 age and sex matched healthy child as control group. MiR-181a expression showed highly significant decrease; plus a significant increase and decrease of Smad7 and TGF-β1 protein levels respectively, in serum samples of ALL as compared to control group. MiR-181a expression achieved a highly significant positive and a significant negative correlation with TGF-β1 and Smad7 respectively. Furthermore, the levels of Smad7 and TGF-β1 were negatively correlated with each other (p<0.05). Although, positivity rate of both Smad7 and TGF-β1 in ALL group increased with presence of hepatosplenomegaly, still there was no statistical significance. In conclusion, miR-181a could act as a tumor suppressor in pediatric ALL with over expression of its target pair, Smad7. Smad7 regulates TGF-β1 signaling via a negative feedback loop and mediates the interaction between TGF-β1 and other signaling pathways; suggesting that Smad7 over expression may have therapeutic potential in ALL.

MicroRNA-181 as a prognostic biomarker for survival in acute myeloid leukemia: a meta-analysis

Accumulating evidence has indicated that microRNA-181 (miR-181) is dysregulated in hematological malignancies, and associates with the clinical outcomes. However, the association of miR-181 expression levels with acute myeloid leukemia (AML) remains inconclusive, as publications from different groups have reported contradictory results. In this manuscript, a meta-analysis was performed to assess the prognostic significance of miR-181 in AML patients. Eligible studies were retrieved from PubMed, Embase and Cochrane Library databases, and a total of 6 studies including 815 AML patients were included in the final analysis. Hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were extracted and pooled to investigate the correlation between miR-181 and the survival of AML patients. Our results showed that elevated miR-181 expression was associated with increased survival in 395 American patients, and reduced survival in 325 Chinese patients. Both subgroup analyses and meta-regression indicated that the origin of AML patients contributed to the heterogeneity in the datasets evaluating the correlation between overall survival (OS) and miR-181. These results indicate that miR-181 can be used as a promising prognostic biomarker in AML patients, which may depend on the origin of patient population.

PP2A inhibition from LB100 therapy enhances daunorubicin cytotoxicity in secondary acute myeloid leukemia via miR-181b-1 upregulation

Patients with secondary acute myeloid leukemia (sAML) arising from myelodysplastic syndromes have a poor prognosis marked by an increased resistance to chemotherapy. An urgent need exists for adjuvant treatments that can enhance or replace current therapeutic options. Here we show the potential of LB100, a small-molecule protein phosphatase 2 A (PP2A) inhibitor, as a monotherapy and chemosensitizing agent for sAML using an in-vitro and in-vivo approach. We demonstrate that LB100 decreases cell viability through caspase activation and G2/M cell-cycle arrest. LB100 enhances daunorubicin (DNR) cytotoxicity resulting in decreased xenograft volumes and improved overall survival. LB100 profoundly upregulates miR-181b-1, which we show directly binds to the 3′ untranslated region of Bcl-2 mRNA leading to its translational inhibition. MiR-181b-1 ectopic overexpression further diminishes Bcl-2 expression leading to suppression of sAML cell growth, and enhancement of DNR cytotoxicity. Our research highlights the therapeutic potential of LB100, and provides new insights into the mechanism of LB100 chemosensitization.

MicroRNA 217 inhibits cell proliferation and enhances chemosensitivity to doxorubicin in acute myeloid leukemia by targeting KRAS

Acute myeloid leukemia (AML) is a heterogeneous malignant disorder derived from the myeloid hematopoietic cells that accounts for ~80% of all adult acute leukemia. Numerous studies have shown that drug resistance not only exists against conventional chemotherapeutic drugs, but also limits the efficacy of new biological agents. Therefore, it is important to identify the mechanisms behind chemoresistance and seek therapeutic strategies to enhance efficacy in AML chemotherapy. MicroRNA (miR)-217 has been recognized as a tumor suppressor that is downregulated in various types of cancer, however the mechanisms behind the expression and function of miR-217 in AML have not yet been recognized. The expression of miR-217 was determined by quantitative polymerase chain reaction (qPCR). Following transfection with miR-217 mimics, an MTT assay, chemosensitivity assay, cell apoptosis assay and western blot analysis were performed in AML cell lines. Functional assays were also performed to explore the effects of endogenous Kirsten rat sarcoma viral oncogene homolog (KRAS) in AML. The results revealed that miR-217 was downregulated in patients with AML. Overexpression of miR-217 inhibited cellular proliferation and enhanced cell chemosensitivity to doxorubicin by the cell apoptosis pathway in AML cells. A dual-luciferase reporter assay demonstrated that KRAS was a direct target gene of miR-217 in vitro. qPCR and western blot analysis revealed that miR-217 negatively regulated KRAS protein expression, but had no impact on KRAS mRNA expression. Knockdown of KRAS expression markedly suppressed AML cellular proliferation, and enhanced cell chemosensitivity to doxorubicin via the cell apoptosis pathway. These findings indicate that miR-217 functions as a tumor suppressor in AML by directly targeting KRAS. Therefore, miR-217-based therapeutic strategies may provide a novel strategy for the enhancement of efficacy in the treatment of AML.