MicroRNAs: pivotal regulators in acute myeloid leukemia

Luteolin Inhibits Lung Cancer Cell Migration by Negatively Regulating TWIST1 and MMP2 Through Upregulation of miR-106a-5p

BACKGROUND

Luteolin, a common dietary flavonoid found in plants, has been shown to have anti-cancer properties. However, its exact mechanisms of action in non-small cell lung cancer (NSCLC) are still not fully understood, particularly its role in regulating broader genomic networks and specific gene targets. In this study, we aimed to elucidate the role of microRNAs (miRNAs) in NSCLC treated with luteolin, using A549 cells as a model system.

MATERIALS AND METHODS

miRNA profiling was conducted on luteolin-treated A549 cells using Exiqon microarrays, with validation of selected miRNAs by qRT-PCR. Bioinformatic analysis identified the regulatory roles of miRNAs in biological processes and pathways following luteolin treatment. Computational algorithms were employed to identify potential target genes. A549 cells were transfected with miR-106a-5p mimic and inhibitor or their corresponding controls. The expression levels of 2 genes, twist basic helix-loop-helix transcription factor 1 (TWIST1) and matrix metallopeptidase 2 (MMP2), and cell migration were assessed.

RESULTS

miRNA profiling identified 341 miRNAs, with 18 exhibiting significantly altered expression (P < 0.05). Subsequent qRT-PCR analysis confirmed altered expression of 6 selected miRNAs. KEGG and GO analyses revealed significant alterations in pathways and biological processes crucial for tumor biology. TWIST1 and MMP2, which both contain conserved miR-106a-5p binding sites, exhibited an inverse correlation with the expression levels of miR-106a-5p. Dual-luciferase reporter assays confirmed TWIST1 and MMP2 as direct targets of miR-106a-5p. Luteolin treatment led to a reduction in A549 cell migration, and this reduction was further amplified by the overexpression of miR-106a-5p.

CONCLUSION

Luteolin inhibits A549 cell migration by modulating the miRNA landscape, shedding light on its mechanisms and laying the foundation for miRNA-based therapeutic approaches for NSCLC.

TET1-mediated microRNA-188-5p promoter hydroxymethylation regulates PTEN/PI3K/AKT signaling pathway in acute myeloid leukemia cells

OBJECTIVE

Acute myeloid leukemia (AML) remains a common hematopoietic malignancy, and drug resistance greatly blunts the efficacy of chemotherapy in AML treatment. Adriamycin (ADM, also called doxorubicin), is one of the most widely used chemotherapeutics for treating cancers. Herein, we studied the molecular mechanisms underlying microRNA-188-5p (miR-188-5p)-mediated ADM resistance in AML.

METHODS

Differentially expressed miRNAs were screened in normal and malignant hematopoietic cells by bioinformatics tools. MiR-188-5p expression in primary bone marrow CD34⁺ cells and AML cells was evaluated. AML/ADM cells were established using THP-1 and Kasumi-1 cells. The effect of miR-188-5p on the drug resistance in AML/ADM cells was examined by delivery of miR-188-5p-inhibitor. The binding relationship between TET1 and miR-188-5p was analyzed by ChIP, and the downstream target of miR-188-5p was predicted by bioinformatics analysis and validated by dual-luciferase assay. Finally, rescue experiments were carried out in vitro and in vivo.

RESULTS

miR-188-5p was highly expressed in AML cells, and miR-188-5p-inhibitor sensitized the AML/ADM cells to ADM. Inhibition of TET1 reduced miR-188-5p promoter hydroxymethylation and downregulated miR-188-5p. miR-188-5p bound to the 3'UTR of PTEN to inhibit PTEN expression, and the PI3K/AKT signaling was activated upon inhibition of PTEN. Suppression of PTEN conferred resistance again to AML/ADM cells in the presence of miR-188-5p inhibitor.

CONCLUSION

TET1 elevates miR-188-5p expression by promoting miR-188-5p promoter hydroxymethylation, and miR-188-5p inhibits PTEN expression to induce PI3K/AKT signaling pathway activation, leading to ADM resistance in AML.

An extended catalogue of ncRNAs in Streptomyces coelicolor reporting abundant tmRNA, RNase-P RNA and RNA fragments derived from pre-ribosomal RNA leader sequences

Streptomyces coelicolor is a model organism for studying streptomycetes. This genus possesses relevant medical and economical roles, because it produces many biologically active metabolites of pharmaceutical interest, including the majority of commercialized antibiotics. In this bioinformatic study, the transcriptome of S. coelicolor has been analyzed to identify novel RNA species and quantify the expression of both annotated and novel transcripts in solid and liquid growth medium cultures at different times. The major characteristics disclosed in this study are: (i) the diffuse antisense transcription; (ii) the great abundance of transfer-messenger RNAs (tmRNA); (iii) the abundance of rnpB transcripts, paramount for the RNase-P complex; and (iv) the presence of abundant fragments derived from pre-ribosomal RNA leader sequences of unknown biological function. Overall, this study extends the catalogue of ncRNAs in S. coelicolor and suggests an important role of non-coding transcription in the regulation of biologically active molecule production.

Repetitive Sequence Transcription in Breast Cancer

Repetitive sequences represent about half of the human genome. They are actively transcribed and play a role during development and in epigenetic regulation. The altered activity of repetitive sequences can lead to genomic instability and they can contribute to the establishment or the progression of degenerative diseases and cancer transformation. In this work, we analyzed the expression profiles of DNA repetitive sequences in the breast cancer specimens of the HMUCC cohort. Satellite expression is generally upregulated in breast cancers, with specific families upregulated per histotype: in HER2-enriched cancers, they are the human satellite II (HSATII), in luminal A and B, they are part of the ALR family and in triple-negative, they are part of SAR and GSAT families, together with a perturbation in the transcription from endogenous retroviruses and their LTR sequences. We report that the background expression of repetitive sequences in healthy tissues of cancer patients differs from the tissues of non-cancerous controls. To conclude, peculiar patterns of expression of repetitive sequences are reported in each specimen, especially in the case of transcripts arising from satellite repeats.

Identification of uPAR Variants Acting as ceRNAs in Leukaemia Cells

Simple Summary

The urokinase (uPA) receptor (uPAR) concentrates proteolytic activities on the cell surface and is an adhesion receptor for vitronectin. Urokinase/Vitronectin binding to uPAR activates intracellular signals promoting cell adhesion, migration, proliferation and survival. Thus, uPAR can sustain most activities of malignant cells and, accordingly, increased uPAR expression is associated with poor prognosis in several malignancies. We previously demonstrated that, in leukaemia cells, the uPAR 3′untranslated region (3′UTR) up-regulates the expression of pro-tumoral factors by recruiting microRNAs targeting their mRNAs, thus acting as competitive endogenous RNA (ceRNA). Here, we identify 3′UTR-containing variants of uPAR mRNA in leukaemia cells and demonstrate that the over-expression of uPAR Δ5-variant mRNA promotes expression of pro-tumoral factors and increase in biological activities, probably by its ceRNA activity. On this basis, we propose that uPAR may play a crucial role in cancer biology also at mRNA level, through the ceRNA activity of its variants.

Abstract

The 3′untranslated region (3′UTR) of the urokinase (uPA) receptor (uPAR) mRNA can act as a competitive endogenous RNA (ceRNA) in acute myeloid leukaemia (AML) cells, promoting the expression of pro-tumoral targets, including uPAR. Here, we identified three variants of uPAR mRNA containing the 3′UTR, in KG1 and U937 leukaemia cells expressing low and high uPAR levels, respectively. Identified variants lack exon 5 (uPAR Δ5) or exon 6 (uPAR Δ6) or part of exon 6, exon 7 and part of 3′UTR (uPAR Δ6/7). uPAR Δ5 and uPAR Δ6 transcript levels were higher in U937 cells compared to KG1 cells. Both uPAR variants were expressed also in AML blasts, at higher levels as compared to CD34 hematopoietic cells from healthy donors. The presence of the 3′UTR conferred high instability to the uPAR Δ5 variant transcript, preventing its translation in protein. Overexpression of the uPAR Δ5-3′UTR variant regulated the expression of some pro-tumoral factors previously reported to be regulated by the 3′UTR of uPAR and increased KG1 cell adhesion, migration and proliferation. These results demonstrate the expression of uPAR mRNA variants containing the 3′UTR in AML cells and the ceRNA activity and the biological effects of the uPAR Δ5-3′UTR variant.

MicroRNAs and exosomes: promising new biomarkers in acute myeloid leukemias?

Despite advances in understanding of carcinogenesis and of treatment of acute myeloid leukemia, this neoplasm still has a lethality of at least 30%. The search for biomarkers that can predict the response to treatment in the early stages of the disease is still necessary. In recent years, a new form of cellular communication between tumor and non-neoplastic cells has been discovered: the exchange of information through extracellular vesicles. These are small vesicles released by membrane-coated cells that carry proteins, lipids, messenger RNAs, microRNA and DNA, which can be internalized and promote biological changes in target cells. Exosomes are qualified as a type of extracellular vesicle and, in tumors, carry immunoinhibitory signals that promote the escape of immune control. Recent studies have showed their involvement in communication with the cells of the tumor microenvironment and with chemoresistance in several tumors. To date, there is no information about immunoregulatory microRNAs transported by exosomes and their correlation with clinical evolution during chemotherapy for acute myeloid leukemia. Knowledge about immunomodulatory microRNAs obtained by leukemic cells and transported by exosomes can direct us towards the design of new diagnostic and treatment tools in this type of leukemia.

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

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

LOC102724163 promotes breast cancer cell proliferation and invasion by stimulating MUC19 expression

Breast cancer (BC) is a malignant disease and the most commonly diagnosed cancer in women. Numerous studies have previously verified the important role of long non-coding RNAs in a number of biological processes in BC. In the present study, analysis of The Cancer Genome Atlas database and reverse transcription-quantitative PCR demonstrated that LOC102724163 expression levels were significantly upregulated in BC tissues compared to matched adjacent normal tissues and were associated with an unfavorable prognosis in patients with BC. Gain or loss of function assays indicated that overexpression of LOC102724163 significantly increased tumorgenicity in vivo and cell migration, proliferation and invasion in vitro. In the mechanistical aspect, LOC102724163 sponged microRNA (miR)-508-5p to elevate MUC19 expression. Additionally, rescue assays ascertained the function of the LOC102724163/miR-508-5p/MUC19 axis in the proliferation and invasion of BC cells. To the best of our knowledge, this is the first study to have demonstrated that LOC102724163 may act as a competing endogenous RNA to control MUC19 expression levels by competitively sponging miR-508-5p to modulate BC progression. Therefore, the present study has provided new insights into BC diagnosis and treatment.

MicroRNAs: emerging driver of cancer perineural invasion

The perineural invasion (PNI), which refers to tumor cells encroaching on nerve, is a clinical feature frequently occurred in various malignant tumors, and responsible for postoperative recurrence, metastasis and decreased survival. The pathogenesis of PNI switches from 'low-resistance channel' hypothesis to 'mutual attraction' theory between peripheral nerves and tumor cells in perineural niche. Among various molecules in perineural niche, microRNA (miRNA) as an emerging modulator of PNI through generating RNA-induced silencing complex (RISC) to orchestrate oncogene and anti-oncogene has aroused a wide attention. This article systematically reviewed the role of microRNA in PNI, promising to identify new biomarkers and offer cancer therapeutic targets.

Human Adipose-Derived Mesenchymal Stem Cells-Derived Exosomal microRNA-19b Promotes the Healing of Skin Wounds Through Modulation of the CCL1/TGF-β Signaling Axis

Introduction

Human adipose-derived mesenchymal stem cells (ADMSCs) with their secretory factors are able to induce collagen synthesis and fibroblast migration in the wound healing process. This study is launched to figure out the effect of human ADMSCs-derived exosomes on skin wound healing.

Methods

ADMSCs were extracted and ADMSCs-derived exosomes were identified. Skin damage models were established by treating HaCaT cells and human skin fibroblasts with H₂O₂. Next, the roles of ADMSCs and their derived exosomes were investigated. The exosomal miRNA then was analyzed, and the function of miRNA on the H₂O₂-induced cells was studied by miRNA suppression. Bioinformatics analysis, luciferase activity and RIP assays were implemented to find the target genes ofthe miRNA and the modulated pathways. A mouse skin damage model was induced to elucidate the effects of exosomes in vivo by injecting exosomes.

Results

H₂O₂ treatment significantly reduced the viability of HaCaT cells and increased their apoptosis rate. Co-culture with ADMSCs or their derived exosomes could improve the cell damage caused by H₂O₂. Meanwhile, H₂O₂ treatment promoted the internalization of exosomes. ADMSCs and their derived exosomes significantly increased miR-19b expression in the recipient cells, while inhibiting miR-19b resulted in a reduction in the therapeutic effect of ADMSCs-derived exosomes. Besides, miR-19b regulated the TGF-β pathway by targeting CCL1. The therapeutic effect of exosomes was further confirmed by a mouse model of skin damage.

Conclusion

Our study indicates that exosomal miR-19b derived from ADMSCs regulates the TGF-β pathway by targeting CCL1, thereby promoting the healing of skin wounds.

Current Understandings of Myeloid Differentiation Inducers in Leukemia Therapy

Differentiation therapy using all-trans retinoic acid for acute promyelocytic leukemia (APL) is well established. Several attempts have been made to treat non-APL, AML patients by employing differentiation inducers, such as hypomethylating agents (HMAs), and low-dose cytarabine (Ara-C) (LDAC), with encouraging results. Other than HMAs and LDAC, various inducers of myeloid cell differentiation have been identified. This review describes and categorizes these inducers, which include glycosylation modifiers, epigenetic modifiers, vitamin derivatives, cytokines, and chemotherapeutic agents. Some of these inducers are currently being used in clinical trials. I highlight the potential applications of glycosylation modifiers and epigenetic modifiers, which are attracting increasing attention in their use as differentiation therapy against AML. Among the agents described in this review, epigenomic modifiers seem particularly promising, and particular attention should also be paid to glycosylation modifiers. These drugs may signal a new era for AML differentiation therapy.

Clusterization in acute myeloid leukemia based on prognostic alternative splicing signature to reveal the clinical characteristics in the bone marrow microenvironment

Background

Alternative splicing (AS), a crucial post-transcriptional regulatory mechanism in expanding the coding capacities of genomes and increasing the diversity of proteins, still faces various challenges in the splicing regulation mechanism of acute myeloid leukemia (AML) and microenvironmental changes.

Results

A total of 27,833 AS events were detected in 8337 genes in 178 AML patients, with exon skip being the predominant type. Approximately 11% of the AS events were significantly related to prognosis, and the prediction models based on various events demonstrated high classification efficiencies. Splicing factors correlation networks further altered the diversity of AS events through epigenetic regulation and clarified the potential mechanism of the splicing pathway. Unsupervised cluster analysis revealed significant correlations between AS and immune features, molecular mutations, immune checkpoints and clinical outcome. The results suggested that AS clusters could be used to identify patient subgroups with different survival outcomes in AML, among which C1 was both associated with good outcome in overall survival. Interestingly, C1 was associated with lower immune scores compared with C2 and C3, and favorable-risk cytogenetics was rarely distributed in C2, but much more common in C1.

Conclusions

This study revealed a comprehensive landscape of AS events, and provides new insight into molecular targeted therapy and immunotherapy strategy for AML.