Knockdown of ZFAS1 suppresses the progression of acute myeloid leukemia by regulating microRNA-150/Sp1 and microRNA-150/Myb pathways

A 69 long noncoding RNA signature predicts relapse and acts as independent prognostic factor in pediatric AML

ABSTRACT

Risk stratification using genetics and minimal residual disease has allowed for an increase in the cure rates of pediatric acute myeloid leukemia (pedAML) to up to 70% in contemporary protocols. Nevertheless, ∼30% of patients still experience relapse, indicating a need to optimize stratification strategies. Recently, long noncoding RNA (lncRNA) expression has been shown to hold prognostic power in multiple cancer types. Here, we aimed at refining relapse prediction in pedAML using lncRNA expression. We built a relapse-related lncRNA prognostic signature, named AMLlnc69, using 871 transcriptomes of patients with pedAML obtained from the Therapeutically Applicable Research to Generate Effective Treatments repository. We identified a 69 lncRNA signature AMLlnc69 that is highly predictive of relapse risk (c-index = 0.73), with area under the receiver operating characteristic curve (AUC) values for predicting the 1-, 2-, and 3-year relapse-free survival (RFS) of 0.78, 0.77, and 0.77, respectively. The internal validation using a bootstrap method (resampling times = 1000) resulted in a c-index of 0.72 and AUC values for predicting the 1-, 2-, and 3-year RFS of 0.77, 0.76, and 0.76, respectively. Through a Cox regression analysis, AMLlnc69, nucleophosmin mutation, and white blood cell at diagnosis were identified as independent predictors of RFS. Finally, a nomogram was build using these 2 parameters, showing a c-index of 0.80 and 0.71 after bootstrapping (n = 1000). In conclusion, the identified AMLlnc69 will, after prospective validation, add important information to guide the management of patients with pedAML. The nomogram is a promising tool for easy stratification of patients into a novel scheme of relapse-risk groups.

Long noncoding RNA ZFAS1 suppresses osteogenic differentiation of bone marrow-derived mesenchymal stem cells by upregulating miR-499-EPHA5 axis

Emerging evidence suggests that the shift between osteogenic and adipogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) determines bone mass. Our study was aimed at testing whether a long noncoding RNA called zinc finger antisense 1 (ZFAS1) participates in the differentiation commitment of BMSCs during osteoporosis. We found that ZFAS1 expression was downregulated during osteogenic differentiation and upregulated during adipogenic differentiation. ZFAS1 knockdown facilitated osteogenic differentiation and suppressed adipogenic differentiation. Furthermore, ZFAS1 knockdown suppressed cell senescence and promoted autophagy. Ovariectomized mice injected with a ZFAS1 knockdown construct showed increased bone mass. Mechanismly, ZFAS1 affected the osteogenic and adipogenic differentiation of BMSCs through sponging miR-499 thereby upregulating ephrin type-A receptor 5 (EPHA5). Taken together, our results revealed that the ZFAS1-miR-499-EPHA5 axis may be important for the osteoporosis-related switch between the osteogenesis and adipogenesis of BMSCs, indicating that ZFAS1 represents a plausible therapeutic target for reversing osteoporotic bone loss.

Intricate crosstalk between MYB and noncoding RNAs in cancer

MYB is often overexpressed in malignant tumors and plays a carcinogenic role in the initiation and development of cancer. Deletion of the MYB regulatory C-terminal domain may be a driving mutation leading to tumorigenesis, therefore, different tumor mechanisms produce similar MYB proteins. As MYB is a transcription factor, priority has been given to identifying the genes that it regulates. All previous attention has been focused on protein-coding genes. However, an increasing number of studies have suggested that MYB can affect the complexity of cancer progression by regulating tumor-associated noncoding RNAs (ncRNAs), such as microRNAs, long-non-coding RNAs and circular RNAs. ncRNAs can regulate the expression of numerous downstream genes at the transcription, RNA processing and translation levels, thereby having various biological functions. Additionally, ncRNAs play important roles in regulating MYB expression. This review focuses on the intricate crosstalk between oncogenic MYB and ncRNAs, which play a pivotal role in tumorigenesis, including proliferation, apoptosis, angiogenesis, metastasis, senescence and drug resistance. In addition, we discuss therapeutic strategies for crosstalk between MYB and ncRNAs to prevent the occurrence and development of cancer.

LncRNA ZFAS1: Role in tumorigenesis and other diseases

Residing on chromosome 20q13.13, Zinc Finger NFX1-Type Containing 1 (ZNFX1) antisense RNA 1 (ZFAS1) is a transcript which has been primarily recognized as a modulator of differentiation of alveolar and epithelial cell in the mammary gland. This long non-coding RNA (lncRNA) partakes in the molecular cascades leading to several non-neoplastic conditions such as osteoarthritis, epilepsy, rheumatoid arthritis, atherosclerosis, pulmonary fibrosis, myocardial infarction, and cardiac dysfunction. More importantly, ZFAS1 is considered as an oncogene in almost all types of cancers. Using expression amounts of ZFAS1, it is possible to forecast the clinical outcome of patients with different neoplasms such as colorectal cancer, gastric cancer, cholangiocarcinoma, hepatoblastoma, and other types of cancer. We describe the role of ZFAS1 in the development of neoplastic and non-neoplastic disorders.

Dysregulation of miRNA in Leukemia: Exploiting miRNA Expression Profiles as Biomarkers

Micro RNAs (miRNAs) are a class of small non-coding RNAs that have a crucial role in cellular processes such as differentiation, proliferation, migration, and apoptosis. miRNAs may act as oncogenes or tumor suppressors; therefore, they prevent or promote tumorigenesis, and abnormal expression has been reported in many malignancies. The role of miRNA in leukemia pathogenesis is still emerging, but several studies have suggested using miRNA expression profiles as biomarkers for diagnosis, prognosis, and response to therapy in leukemia. In this review, the role of miRNAs most frequently involved in leukemia pathogenesis is discussed, focusing on the class of circulating miRNAs, consisting of cell-free RNA molecules detected in several body fluids. Circulating miRNAs could represent new potential non-invasive diagnostic and prognostic biomarkers of leukemia that are easy to isolate and characterize. The dysregulation of some miRNAs involved in both myeloid and lymphoid leukemia, such as miR-155, miR-29, let-7, and miR-15a/miR-16-1 clusters is discussed, showing their possible employment as therapeutic targets.

MicroRNA-150 inhibits myeloid-derived suppressor cells proliferation and function through negative regulation of ARG-1 in sepsis

AIMS

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. The majority of sepsis-related deaths occur during late sepsis, which presents as a state of immunosuppression. Myeloid-derived suppressor cells (MDSCs) have been reported to promote immunosuppression during sepsis. Here we aim to understand the role of microRNAs in regulating MDSCs proliferation and immunosuppression function during sepsis.

MAIN METHODS

Murine sepsis model was established using cecal ligation and puncture (CLP). A microarray was used to identify microRNAs with differential expression in murine sepsis. The effect of microRNA-150 on MDSCs proliferation and function was then evaluated. 140 multiple trauma patients from Tongji Hospital and 10 healthy controls were recruited. Peripheral blood samples were taken and the serum level of miR-150 was measured.

KEY FINDINGS

In the murine model of sepsis, MDSCs expansion was noted in the spleen and bone marrow, while expression of miR-150 in MDSCs decreased. Replenishing miR-150 inhibited the expansion of MDSCs in both monocytic and polymorphonuclear subpopulations, as well as decreasing the immunosuppressive function of MDSCs, through down-regulation of ARG1. Both pro-inflammatory cytokine IL-6 and anti-inflammatory cytokines TGF-β and IL-10 were reduced by miR-150. In human, the serum level of miR-150 was down-regulated in septic patients and elevated in non-septic trauma patients compared to healthy controls.

SIGNIFICANCE

Our study showed that MiR-150 is down-regulated during sepsis. Replenishing miR-150 reduces the immunosuppression function of MDSCs by down-regulating ARG1 in late sepsis. MiR-150 might serve as a potential therapeutic option for sepsis.

LncRNA ZFAS1, as a poor prognostic indicator, promotes cell proliferation and epithelial-mesenchymal transition in endometrial carcinoma

Background: Long noncoding RNA Zinc finger nuclear transcription factor, X-box binding 1-type containing 1 antisense RNA 1 (ZFAS1) has been reported to be an oncogene in various tumors. However, the role of ZFAS1 in endometrial carcinoma (EC) are not fully determined. Methods & results: Here, we found ZFAS1 expression was significantly upregulated in EC patients, which was significantly associated with International Federation of Gynecology and Obstetrics stage, histological grade, myometrial invasion and poor prognosis. The loss-of-function assays showed that knockdown of ZFAS1 significantly suppressed the proliferation, G1/S transition, migration and invasion in EC cells. Moreover, knockdown of ZFAS1 obviously downregulated the expression of CDK4, Cyclin D1 and N-cadherin, but upregulated E-cadherin expression. Conclusion: Collectively, these results suggest that ZFAS1 might be used as potential therapeutic targets for EC treatment.

LINC00963 facilitates acute myeloid leukemia development by modulating miR-608/MMP-15

Despite continuous improvements of AML therapy, the prognosis of AML patients remains unsatisfactory. Recently, lncRNAs have been reported to participate in the development of AML. Our data demonstrated that MMP15 and LINC00963 were upregulated and miR-608 was decreased in AML cells (THP-1, HL-60, HEL and MOLM-13) compared to HS-5 cells. RT-qPCR results showed that LINC00963 levels were higher in the serum and bone marrow of AML cases than in controls. Moreover, overexpression of LINC00963 promoted AML cell growth and EMT progression in both THP-1 and HL-60 cells. Furthermore, miR-608 levels were downregulated in the serum and bone marrow of AML cases compared with controls, and Pearson's correlation analysis indicated that LINC00963 was negatively correlated with miR-608 in the serum and bone marrow of AML samples. In addition, we demonstrated that LINC00963 sponged miR-608 expression and that MMP-15 was a target of miR-608 in AML cells. Finally, rescue experiments indicated that ectopic expression of LINC00963 accelerated cell growth and EMT development by modulating MMP-15. These data demonstrated that LINC00963 acted as an oncogene and may be a potential target for AML treatment.

v-myb avian myeloblastosis viral oncogene homolog expression is a potential molecular diagnostic marker for B-cell acute lymphoblastic leukemia

BACKGROUND

B-cell acute lymphoblastic leukemia (B-ALL) is the most commonly diagnosed childhood malignancy worldwide and is especially common in Mexico. Additionally, the number of cases has increased in recent years. Thus, it is very important to develop molecular strategies to diagnose leukemia. The aim of this study was to investigate MYB expression and to determine its impact on the diagnosis of B-ALL.

METHODS

We analyzed the B-ALL gene expression profile by microarray data mining. Bioinformatics analysis was performed to identify the genes that are overexpressed in leukemia. We determined that MYB was highly expressed in leukemia. Then, we validated MYB expression in 70 patients with B-ALL and in 16 healthy controls (HCs) using qRT-PCR. The results were statistically analyzed using the Kolmogorov-Smirnov Z test, Mann-Whitney U test, receiver operating characteristic curves, and the Youden index.

RESULTS

The microarrays showed that MYB was overexpressed in B-ALL patients with a fold change of 57.8728 and a P value of 2.56^-195 . MYB expression showed great variability among the patients analyzed. However, compared to the HCs, the B-ALL patients had a P value < .0001, an area under the curve of 0.813, and a Youden index of 1.46, indicating the statistical significance.

CONCLUSION

MYB expression in B-ALL cells could be a potential molecular marker for childhood leukemia.

Long non-coding RNA UCA1 modulates cell proliferation and apoptosis by regulating miR-296-3p/Myc axis in acute myeloid leukemia

Acute myeloid leukemia (AML) is a common hematopoietic malignancy with a generally poor prognosis. Long non-coding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) has been identified as an oncogene in various malignancies including AML. However, the role and mechanisms of UCA1 in AML tumorigenesis were incompletely understood. Hence, this study aims to investigate whether UCA1 regulates AML progression by miR-296-3p/Myc axis. Cell proliferation and apoptosis were evaluated by MTT assay and flow cytometry, respectively. Luciferase reporter assay was performed to analyze the interaction between miR-296-3p and UCA1 or Myc. The results showed that UCA1 knockdown inhibited proliferation and induced apoptosis in AML cells (U937 and HL60). Mechanistically, UCA1 acted as a sponge of miR-296-3p by binding to miR-296-3p. Myc, a target of miR-296-3p, was positively regulated by UCA1. Functional assay showed that the anti-AML effect of UCA1 knockdown could be abrogated by miR-296-3p inhibition and Myc overexpression. Moreover, UCA1 knockdown inhibited AML cell tumorigenesis in vivo, which was associated with regulation of miR-296-3p and Myc expression. In conclusion, UCA1 modulates AML progression by regulating miR-296-3p/Myc axis.

MiR-100 regulates cell viability and apoptosis by targeting ATM in pediatric acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common pediatric malignancy and a major cause of morbidity and mortality in children. miR-100 is associated with progression of various diseases including AML. The aim of this study was to explore the underlying molecule mechanisms of miR-100 involved in AML. The expressions of miR-100 and ataxia telangiectasia mutated (ATM) in pediatric AML patients and cell lines were monitored using qRT-PCR and western blot assays. MTT assay was carried to evaluate cell viability. Cell apoptosis was measured by flow cytometry. The binding sites between miR-100 and ATM were predicted by mirtarbase database. Luciferase reporter assay was used to confirm the relationship between miR-100 and ATM. miR-100 expression was highly expressed in bone marrow of AML patients and cell lines. Moreover, Knockdown of miR-100 led to the inhibition of viability and promotion of apoptosis in Kasumi-1 and MV-4-11 cells. miR-100 harbored the 3'UTR of ATM. Meanwhile, the expression of ATM was downregulated in bone marrow of AML patients and AML cell lines. Subsequently, a negative correlation between miR-100 and ATM in bone marrow of AML patients was also observed. Furthermore, ectopic expression of ATM repressed cell viability while enhanced apoptosis. Notably, loss of ATM attenuated the effect of miR-100 depletion on cell viability and apoptosis in AML cells. miR-100 participates in cell viability and apoptosis by targeting ATM in pediatric AML.

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

Background

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

Methods

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

Results

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

Conclusion

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

The regulation and interaction of PVT1 and miR181a-5p contributes to the repression of SP1 expression by the combination of XJD decoction and cisplatin in human lung cancer cells

The Chinese herbal prescription Xiaoji decoction (XJD) has been used as an adjuvant treatment of cancer for decades. However, the molecular mechanisms underlying XJD enhancement of the efficiency of chemotherapy were undetermined. In this study, we observed that combination of XJD and cisplatin (DDP) showed a greater inhibition on growth and induced a high magnitude of apoptosis in non-small cell lung cancer (NSCLC) cells. We also found that XJD decreased lncRNA PVT1 and increased miR181a-5p expressions. There was a reciprocal interaction between PVT1 and miR181a-5p. XJD decreased SP1 protein, which were overcame by overexpressed PVT1 and inhibitors of miR181a-5p. Overexpressed SP1 reversed the inhibitory effect of XJD on cell growth. Importantly, XJD and DDP exhibited synergy on regulation of PVT1, miR181a-5p, and SP1 expressions. The similar results were observed in one in vivo model. In conclusions, XJD inhibits NSCLC cell growth via reciprocal interaction of PVT1 and miR181a-5p followed by reducing SP1 expression. XJD and DDP exhibit synergy. This study provides a novel mechanism by which XJD enhances the anti-cancer effect of DDP in NSCLC cells.

Silencing lncRNA ZFAS1 or elevated microRNA-135a represses proliferation, migration, invasion and resistance to apoptosis of osteosarcoma cells

Background

Osteosarcoma (OS) is still a disease with high mortality from malignant tumors in children and adolescents. Due to its poor treatment, this study explored the involvement of lncRNA ZFAS1/microRNA-135a (miR-135a)/apurinic/apyrimidinic exonuclease 1 (APEX1) axis in the regulation of OS growth and metastasis.

Methods

ZFAS1, miR-135a and APEX1 expression in OS tissues and cells were tested by RT-qPCR and western blot analysis. MG63 cells were transfected with sh-ZFAS1, miR-135a mimic or their controls to unearth theirs functions in the proliferation, colony formation, migration, invasion, cycle entry and apoptosis of MG63 cells by MTT and EdU, colony formation assays, flow cytometry, and Transwell assay, severally. The proliferation related factor (Ki-67, CyclinD1), apoptosis related factor (Bax, Bcl-2) and migration related factor (MMP2, MMP9) protein levels were tested. Tumor volume and weight were detected by subcutaneous tumor xenograft in nude mice.

Results

Overexpressed ZFAS1 and APEX1, and down-regulated miR-135a existed in OS tissues and cells. Silenced ZFAS1 or elevated miR-135a inhibited colony formation and proliferation, cycle progression, migration and invasion while promoted apoptosis of MG63 cells. Silenced ZFAS1 or elevated miR-135a suppressed tumor volume and weight of OS in vivo. LncRNA ZFAS1 promoted APEX1 expression by competitively binding with miR-135a.

Conclusion

This study indicates that silenced ZFAS1 or up-regulated miR-135a restrained migration, proliferation and invasion and promoted apoptosis of OS MG63 cells. This study provides a possible theoretical basis for studying the regulatory mechanism of ZFAS1/miR-135a/APEX1 signaling axis on the growth and metastasis of OS.

Long Noncoding RNAs in Acute Myeloid Leukemia: Functional Characterization and Clinical Relevance

Acute Myeloid Leukemia (AML) is the most common form of leukemia in adults with an incidence of 4.3 per 100,000 cases per year. Historically, the identification of genetic alterations in AML focused on protein-coding genes to provide biomarkers and to understand the molecular complexity of AML. Despite these findings and because of the heterogeneity of this disease, questions as to the molecular mechanisms underlying AML development and progression remained unsolved. Recently, transcriptome-wide profiling approaches have uncovered a large family of long noncoding RNAs (lncRNAs). Larger than 200 nucleotides and with no apparent protein coding potential, lncRNAs could unveil a new set of players in AML development. Originally considered as dark matter, lncRNAs have critical roles to play in the different steps of gene expression and thus affect cellular homeostasis including proliferation, survival, differentiation, migration or genomic stability. Consequently, lncRNAs are found to be differentially expressed in tumors, notably in AML, and linked to the transformation of healthy cells into leukemic cells. In this review, we aim to summarize the knowledge concerning lncRNAs functions and implications in AML, with a particular emphasis on their prognostic and therapeutic potential.

Long Non-coding RNAs in Myeloid Malignancies

Acute myeloid leukemia (AML) represents 80% of adult leukemias and 15-20% of childhood leukemias. AML are characterized by the presence of 20% blasts or more in the bone marrow, or defining cytogenetic abnormalities. Laboratory diagnoses of myelodysplastic syndromes (MDS) depend on morphological changes based on dysplasia in peripheral blood and bone marrow, including peripheral blood smears, bone marrow aspirate smears, and bone marrow biopsies. As leukemic cells are not functional, the patient develops anemia, neutropenia, and thrombocytopenia, leading to fatigue, recurrent infections, and hemorrhage. The genetic background and associated mutations in AML blasts determine the clinical course of the disease. Over the last decade, non-coding RNAs transcripts that do not codify for proteins but play a role in regulation of functions have been shown to have multiple applications in the diagnosis, prognosis and therapeutic approach of various types of cancers, including myeloid malignancies. After a comprehensive review of current literature, we found reports of multiple long non-coding RNAs (lncRNAs) that can differentiate between AML types and how their exogenous modulation can dramatically change the behavior of AML cells. These lncRNAs include: H19, LINC00877, RP11-84C10, CRINDE, RP11848P1.3, ZNF667-AS1, AC111000.4-202, SFMBT2, LINC02082-201, MEG3, AC009495.2, PVT1, HOTTIP, SNHG5, and CCAT1. In addition, by performing an analysis on available AML data in The Cancer Genome Atlas (TCGA), we found 10 lncRNAs with significantly differential expression between patients in favorable, intermediate/normal, or poor cytogenetic risk categories. These are: DANCR, PRDM16-DT, SNHG6, OIP5-AS1, SNHG16, JPX, FTX, KCNQ1OT1, TP73-AS1, and GAS5. The identification of a molecular signature based on lncRNAs has the potential for have deep clinical significance, as it could potentially help better define the evolution from low-grade MDS to high-grade MDS to AML, changing the course of therapy. This would allow clinicians to provide a more personalized, patient-tailored therapeutic approach, moving from transfusion-based therapy, as is the case for low-grade MDS, to the introduction of azacytidine-based chemotherapy or allogeneic stem cell transplantation, which is the current treatment for high-grade MDS.

The implication of lncRNA expression pattern and potential function of lncRNA RP4-576H24.2 in acute myeloid leukemia

BACKGROUND

Recent studies have revealed that long noncoding RNAs (lncRNAs) may hold crucial triggers of the pathogenesis of hematological malignancies, while the studies evaluating the expression pattern of lncRNA in acute myeloid leukemia (AML) are few. Thus, this study aimed to investigate the implication of lncRNA expression pattern in AML development and progression.

METHODS

Bone marrow samples from four AML patients and four controls were subjected to lncRNA sequencing. Then, bone marrow samples from 110 AML patients and 40 controls were proposed to real-time quantitative polymerase chain reaction (RT-qPCR) validation for 10 candidate lncRNAs. Clinical data and survival profiles were recorded in AML patients. Furthermore, lncRNA RP4-576H24.2 expression in AML cell lines and its effect on AML cell proliferation and apoptosis were detected.

RESULTS

LncRNA expression pattern by sequencing clearly distinguished AML patients from controls, and 630 upregulated and 621 downregulated lncRNAs were identified in AML patients compared to controls, which were mainly enriched in AML oncogene-related biological process and pathways (such as neutrophil degranulation, leukocyte transendothelial migration, and hematopoietic cell lineage). RT-qPCR validation observed that six lncRNAs correlated with AML risk, one lncRNA associated with risk stratification, and three lncRNAs correlated with survivals, among which lncRNA RP4-576H24.2 was the only one correlated with AML susceptibility, risk stratification, and survivals. Further in vitro experiments showed that lncRNA RP4-576H24.2 was upregulated in AML cell lines compared to normal bone marrow mononuclear cells (BMMCs), and promoted proliferation while inhibited apoptosis in HL-60 and KG-1 cells.

CONCLUSIONS

LncRNA expression pattern is closely involved in the development and progression of AML, and several specific lncRNAs exhibit potential to be biomarkers for AML risk and prognosis. Besides, lncRNA RP4-576H24.2 might be a potential oncogene in AML pathogenesis.

Long noncoding RNA ZFAS1 enhances adriamycin resistance in pediatric acute myeloid leukemia through the miR-195/Myb axis

Background: Development of chemoresistance remains a major obstacle for pediatric acute myeloid leukemia (AML) management. Zinc finger antisense 1 (ZFAS1) is a novel tumor-related lncRNA that has been reported as an oncogene involved in the development of pediatric AML. The purpose of the present study was to investigate the role and underlying mechanism of ZFAS1 in AML chemoresistance. Methods: The expression levels of ZFAS1 and miR-195 were assessed by qRT-PCR and Myb expression was detected using western blotting. The CCK-8 assay was used to determine the IC50 value for adriamycin (ADR) and cell proliferation. Cell apoptosis was measured by flow cytometry. The targeted interaction between miR-195 and ZFAS1 or Myb was evaluated by the dual-luciferase reporter assay or RNA immunoprecipitation assay. Results: Our data revealed that ADR treatment induced ZFAS1 expression in pediatric AML. Silencing of ZFAS1 or Myb alleviated AML cell resistance to ADR in vitro. ZFAS1 directly targeted miR-195 and negatively modulated miR-195 expression. Myb was a direct target of miR-195. Moreover, the inhibitory effect of ZFAS1 silencing on ADR resistance of AML cells was mediated by miR-195 in vitro. Myb was involved in the regulation of the ZFAS1/miR-195 axis in ADR resistance of AML cells. Conclusion: Our data indicated that ZFAS1 silencing alleviated ADR resistance of AML cells in vitro through acting as a sponge for miR-195 and regulating Myb expression. Targeting ZFAS1 might be a promising therapeutic strategy for pediatric AML treatment.

MiR-29b/Sp1/FUT4 axis modulates the malignancy of leukemia stem cells by regulating fucosylation via Wnt/β-catenin pathway in acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is initiated and maintained by a unique, small subset of leukemia stem cells (LSCs). LSCs are characterized by unrestricted self-renewal and contribute to the malignancy of leukemia. Aberrant protein fucosylation is associated with AML progression. However, it is still less understood that the miR-29b/Sp1/FUT4 crosstalk involved in the fucosylation-mediated LSCs malignancy in AML.

METHODS

AML cell lines were sorted by magnetic microbeads to obtain the CD34 + CD38- sub-population. The key biomarkers for LSCs were identified by flow cytometry. Fucosyltransferase genes were screened by qRT-PCR, and FUT4 was focused. Effect of FUT4 on LSCs malignancy was determined by CCK8 assay, sphere formation assay, immunofluorescence staining, apoptosis and in vivo xenografts experiments. The linkage of FUT4 promoter and Sp1 was confirmed by dual-luciferase reporter gene assay. ChIP-PCR assay was used to show the directly binding of Sp1 and FUT4 promoter. Activity of Wnt//β-catenin pathway was determined by western blot. Overall survival curves were diagrammed by Kaplan-Meier analysis.

RESULTS

Here, the expressional profiles of 11 fucosyltransferase genes were different comparing LSCs and non-LSCs of KG-1a and MOLM13 cells, whereas CD34 + CD38- cells exhibited higher expression of FUT4. Functionally, alteration of FUT4 in CD34 + CD38- cells modulated LSCs malignant behaviors both in vitro and in vivo. Transcriptional inhibitor actinomycin D (Act D) or translational inhibitor cycloheximide (CHX) prevented LSCs progression, and Sp1 was identified as the efficient regulator of FUT4 transcription. Moreover, miR-29b directly affected the binding of Sp1 and FUT4 promoter region, which further mediated LSCs proliferation, apoptosis and drug-resistance through fucosylated-CD44 via activation of Wnt/β-catenin pathway. Clinically, Sp1 and FUT4 were up-regulated and positively correlated with poor overall survival of AML patients.

CONCLUSION

These data indicated that miR-29b/Sp1/FUT4 axis promoted the malignant behaviors of LSCs by regulating fucosylated CD44 via Wnt/β-catenin pathway. Identifying LSCs surface markers and targeting LSCs were important for the development of potential therapies in AML.