Role of miRNA-424 in Cancers

Vorinostat impairs the cancer-driving potential of leukemia-secreted extracellular vesicles

BACKGROUND

Leukemia-secreted extracellular vesicles (EVs) carry biologically active cargo that promotes cancer-supportive mechanisms, including aberrant proliferative signaling, immune escape, and drug resistance. However, how antineoplastic drugs affect EV secretion and cargo sorting remains underexplored.

METHODS

Leukemia-secreted extracellular vesicles (EVs) were isolated by Differential UltraCentrifugation, and their miRNome and proteomic profiling cargo were analyzed following treatment with SAHA (Vorinostat) in Acute Myeloid Leukemia (AML) and Chronic Myeloid Leukemia (CML). The epigenetic modulation of leukemia-secreted EVs content on interesting key target molecules was validated, and their differential functional impact on cellular viability, cell cycle progression, apoptosis, and tumorigenicity was assessed.

RESULTS

SAHA significantly alters the cargo of Leukemia-derived EVs, including miR-194-5p and its target BCLAF1 (mRNA and protein), key regulators of Leukemia cell survival and differentiation. SAHA upregulates miR-194-5p expression while selective loading BCLAF1 into EVs, reducing the miRNA levels in the same compartment. Additionally, SAHA alters miRNA profile and proteomic composition associated with leukemic EVs, altering their tumor-supportive potential, with differential effects observed between AML and CML. Furthermore, in silico predictions suggest that these modified EVs may influence cell sensitivity to antineoplastic agents, suggesting a dual role for SAHA in impairing oncogenic signaling while enhancing therapeutic responsiveness.

CONCLUSIONS

In conclusion, the capacity of SAHA to modulate secretion and molecular composition of Leukemia-secreted EVs, alongside its direct cytotoxic effects, underscores its potential in combination therapies aimed to overcoming refractory phenotype by targeting EV-mediated communication.

Plasma miRNAs in polycystic ovary syndrome drive endometrial cancer progression: insights into molecular pathways and therapeutic targets

Polycystic ovary syndrome (PCOS) is a known risk factor for uterine endometrial cancer (UCEC), but its underlying mechanisms remain unclear. MicroRNAs (miRNAs) could provide insights into these mechanisms and reveal potential therapeutic targets. Differential miRNA expression was analyzed in plasma exosomes from 15 PCOS and 15 control samples. Survival analysis assessed the prognostic value of these miRNAs in UCEC. MiRNA-target gene interaction networks and gene co-expression analyses were used to explore molecular mechanisms. Validation was performed using experimental data from Ishikawa cells treated with six candidate drugs. Among the 15 differentially expressed miRNAs, 12 were up-regulated and 3 were down-regulated in PCOS. Twelve of these miRNAs were associated with UCEC overall survival, with miR-142, miR-424, and miR-331 acting as protective factors, while the remaining 9 miRNAs were identified as risk factors. MiRNA-target network highlighted key genes such as PHF8, LCOR, SFT2D3, E2F1, and ESR1, which were found to be prognostic for patient survival. Further gene expression and co-expression analyses based on miR-424 and miR-330 expression revealed significant alterations in gene expression and cellular processes related to UCEC. Two-sample Mendelian randomization analysis identified potential causal relationships between AURKA gene expression and PCOS or UCEC. Testosterone and estradiol might have adverse roles in UCEC, while drugs like troglitazone, valproic acid, retinoic acid, and progesterone demonstrated various effects on gene expression and cellular processes. Our findings suggest that aberrant miRNA expression, particularly miR-330 and miR-424, may play crucial roles in UCEC progression. The identified miRNAs and candidate drugs may serve as potential therapeutic targets for UCEC, but further research is required to validate and explore their clinical applications.

In silico, in vitro, and ex vivo analysis reveals miR-27a-3p and miR-155-5p as key microRNAs for glioblastoma progression: Insights into Th1 differentiation and apoptosis induction

We explored key microRNAs (miRNAs) related to tumorigenesis and immune modulation in glioblastoma (GBM), employing in silico, in vitro, and ex vivo analysis along with an assessment of the cellular impacts resulting from miRNA inhibition. GBM and T cells miRNA expression profiles from public datasets were used to evaluate differentially expressed miRNAs (DEmiRNAs). Some DEmiRNAs were chosen for validation in GBM cell lines, primary cell cultures, and brain tumor patient samples, using RT-qPCR. Target genes and pathways were identified with bioinformatic analyses. In silico functional enrichment analysis revealed that miR-27a-3p and miR-155-5p modulate immune, metabolic, and GBM-related pathways. A172 cells were transfected with miRNA inhibitors and the effects on cellular processes and immunomodulation were analyzed by co-culture assays and flow cytometry. Upon validation, miR-27a-3p and miR-155-5p miRNAs expressions were consistently increased. Inhibiting these two miRNAs reduced cell viability, but only the inhibition of miR-27a-3p led to apoptosis. Co-culture assays showed an increase in Th1 cells along with elevated Th1/Treg and Th17/Treg ratios, and an increase in Th17 cells exclusively with miR-155-5p inhibition. Immune cells' gene expression modulation induced an antitumor profile, concomitant with an increase in the expression of apoptotic genes in cancer cells after co-culture. This study unveils potential targets for immune and tumor regulation, highlighting overexpressed miRNAs modulation as a novel therapeutic approach for GBM.

Drug resistance in ovarian cancer: from mechanism to clinical trial

Ovarian cancer is the leading cause of gynecological cancer-related death. Drug resistance is the bottleneck in ovarian cancer treatment. The increasing use of novel drugs in clinical practice poses challenges for the treatment of drug-resistant ovarian cancer. Continuing to classify drug resistance according to drug type without understanding the underlying mechanisms is unsuitable for current clinical practice. We reviewed the literature regarding various drug resistance mechanisms in ovarian cancer and found that the main resistance mechanisms are as follows: abnormalities in transmembrane transport, alterations in DNA damage repair, dysregulation of cancer-associated signaling pathways, and epigenetic modifications. DNA methylation, histone modifications and noncoding RNA activity, three key classes of epigenetic modifications, constitute pivotal mechanisms of drug resistance. One drug can have multiple resistance mechanisms. Moreover, common chemotherapies and targeted drugs may have cross (overlapping) resistance mechanisms. MicroRNAs (miRNAs) can interfere with and thus regulate the abovementioned pathways. A subclass of miRNAs, "epi-miRNAs", can modulate epigenetic regulators to impact therapeutic responses. Thus, we also reviewed the regulatory influence of miRNAs on resistance mechanisms. Moreover, we summarized recent phase I/II clinical trials of novel drugs for ovarian cancer based on the abovementioned resistance mechanisms. A multitude of new therapies are under evaluation, and the preliminary results are encouraging. This review provides new insight into the classification of drug resistance mechanisms in ovarian cancer and may facilitate in the successful treatment of resistant ovarian cancer.

TP53 mitigates cisplatin resistance in non-small cell lung cancer by mediating the effects of resistant cell-derived exosome mir-424-5p

Background

Cisplatin (DDP) is the principal agent used for chemotherapy in patients with non-small cell lung cancer (NSCLC). Nevertheless, DDP resistance is an essential cause for a worse prognosis of patient. Therefore, this study proposes to discover features of miR-424-5p in DDP resistance of NSCLC.

Method

After exogenous modulation of miR-424-5p expression, A549 cell activity was measured using CCK-8 and flow cytometry. A549/DDP and A549/DDP-associated subcutaneous tumor model were constructed to investigate the effect of miR-424-5p on DDP resistance in NSCLC in vivo. TargetScan and JASPAR databases predicted the potential molecular mechanism of miR-424-5p. A549-and A549/DDP-derived exosomes were isolated and characterized using a transmission electron microscope and nanoparticle tracking analysis.

Result

Overexpression of miR-424-5p facilitated proliferation and DDP resistance in A549 cells, and knockdown of miR-424-5p did the opposite. Knockdown of miR-424-5p enhanced DDP restriction on tumor weight and volume. Moreover, SOCS5 and SOCS56 (SOCS5/6) were downstream targets of miR-424-5p. miR-424-5p down-regulated SOCS5/6 expression to activate JAK2/STAT3 and PI3K/AKT pathways. Notably, tumor protein p53 (TP53) is a transcription factor for the miR-424-5p host gene, as confirmed by the dual-luciferase reporter gene. Cellular and animal experiments indicated that TP53 limited the regulatory function of miR-424-5p on NSCLC growth, DDP resistance, and related molecules. Interestingly, miR-424-5p was markedly enriched in A549/DDP cell-derived exosomes than in A549 cell-derived exosomes, and TP53 down-regulated miR-424-5p expression in A549/DDP cell-derived exosomes.

Conclusion

DDP-resistant cell-derived exosome miR-424-5p contributes to NSCLC growth and DDP resistance by targeting SOCS5 and SOCS6 to activate JAK2/STAT3 and PI3K/AKT pathways, which are blocked by TP53.

Determination of T-cell clonality and expression profiles of Toll-like receptors signaling pathway genes and related miRNAs in patients with mycosis fungoides

Cutaneous T-cell lymphomas (CTCL) encompass a group of diseases characterized by the presence of malignant clonal CD4+ T lymphocytes in the skin. Mycosis fungoides (MF) is the most prevalent form of CTCL, accounting for approximately 60 % of cutaneous T-cell lymphomas and 50 % of all primary cutaneous lymphomas. Despite ongoing research, the precise pathogenesis of MF remains incompletely understood. Toll-like receptors (TLRs) have the ability to specifically recognize ligands, subsequently induce the expression of diverse genes and activate innate immunity within the cell. Furthermore, miRNAs play a crucial role in regulating various aspects of immune cell function. The aim of our study was to explore the potential roles of TLRs and the genes implicated in their signal transduction, along with the expression status of miRNAs in the mechanisms underlying MF. Additionally, we assessed the clonal status and compared it with clinicopathological data using a T-cell clonality assay. To determine the expression status of TLR pathway genes and miRNAs, we conducted RT-PCR analysis on 52 MF samples and 50 control paraffin block materials. Pathway analysis were conducted using the KEGG database. T-cell receptor (TCR) gamma clonality changes were evaluated. Results from the study revealed increased expressions of TLR-1, -4, -8, IRF7, TRAF3, MEK1, MEK2, Elk1, NFkB, hsa-miR-21-5p, and hsa-miR-155-5p, as well as decreased expressions of hsa-miR-130a-3p, hsa-miR-210-3p, and hsa-let-7e-5p in the MF group. TCR gamma clonal change analysis demonstrated that 55.5 % of the analysed DNAs exhibited monoclonal and biallelic patterns, while 45.5 % displayed polyclonality. These findings collectively suggest the potential influence and therapeutic possibilities of the TLR signalling pathway in the molecular pathogenesis of MF.

Mesenchymal stem cell-derived microRNAs: Friends or foes of tumor cells?

Mesenchymal stem cell (MSC)-dependent biological effects in the tumor microenvironment mainly rely on the activity of MSC-sourced microRNAs (MSC-miRNAs) which modulate protein synthesis in target tumor cells, endothelial cells and tumor-infiltrated immune cells, regulating their phenotype and function. Several MSC-sourced miRNAs (miR-221, miR-23b, miR-21-5p, miR-222/223, miR-15a miR-424, miR-30b, miR-30c) possess tumor-promoting properties and are able to enhance viability, invasiveness and metastatic potential of malignant cells, induce proliferation and sprouting of tumor endothelial cells and suppress effector functions of cytotoxic tumor-infiltrated immune cells, crucially contributing to the rapid growth and progression of tumor tissue. On the contrary, MSCs also produce "anti-tumorigenic" miRNAs (miR-100, miR-222-3p, miR-146b miR-302a, miR-338-5p, miR-100-5p and miR-1246) which suppress tumor growth and progression by: Up-regulating expression of chemoresistance-related genes in tumor cells, by suppressing neo-angiogenesis and by inducing generation of tumorotoxic phenotypes in tumor-infiltrated lymphocytes. In this review article, we summarize the current knowledge about molecular mechanisms that are responsible for MSC-miRNA-dependent alterations of intracellular signaling in tumor and immune cells and we discuss different insights regarding the therapeutic potential of MSC-derived miRNAs in cancer treatment.

The Importance of the Immune System and Molecular Cell Signaling Pathways in the Pathogenesis and Progression of Lung Cancer

Lung cancer is a disease that in recent years has become one of the greatest threats to modern society. Every year there are more and more new cases and the percentage of deaths caused by this type of cancer increases. Despite many studies, scientists are still looking for answers regarding the mechanisms of lung cancer development and progression, with particular emphasis on the role of the immune system. The aim of this literature review was to present the importance of disorders of the immune system and the accompanying changes at the level of cell signaling in the pathogenesis of lung cancer. The collected results showed that in the process of immunopathogenesis of almost all subtypes of lung cancer, changes in the tumor microenvironment, deregulation of immune checkpoints and abnormalities in cell signaling pathways are involved, which contribute to the multistage and multifaceted carcinogenesis of this type of cancer. We, therefore, suggest that in future studies, researchers should focus on a detailed analysis of tumor microenvironmental immune checkpoints, and to validate their validity, perform genetic polymorphism analyses in a wide range of patients and healthy individuals to determine the genetic susceptibility to lung cancer development. In addition, further research related to the analysis of the tumor microenvironment; immune system disorders, with a particular emphasis on immunological checkpoints and genetic differences may contribute to the development of new personalized therapies that improve the prognosis of patients.

Research progress on anti-ovarian cancer mechanism of miRNA regulating tumor microenvironment

Ovarian cancer is the most deadly malignancy among women, but its complex pathogenesis is unknown. Most patients with ovarian cancer have a poor prognosis due to high recurrence rates and chemotherapy resistance as well as the lack of effective early diagnostic methods. The tumor microenvironment mainly includes extracellular matrix, CAFs, tumor angiogenesis and immune-associated cells. The interaction between tumor cells and TME plays a key role in tumorigenesis, progression, metastasis and treatment, affecting tumor progression. Therefore, it is significant to find new tumor biomarkers and therapeutic targets. MicroRNAs are non-coding RNAs that post-transcriptionally regulate the expression of target genes and affect a variety of biological processes. Studies have shown that miRNAs regulate tumor development by affecting TME. In this review, we summarize the mechanisms by which miRNAs affect ovarian cancer by regulating TME and highlight the key role of miRNAs in TME, which provides new targets and theoretical basis for ovarian cancer treatment.

Progress in the studies on the molecular mechanisms associated with multidrug resistance in cancers

Chemotherapy is one of the important methods to treat cancer, and the emergence of multidrug resistance (MDR) is one major cause for the failure of cancer chemotherapy. Almost all anti-tumor drugs develop drug resistance over a period of time of application in cancer patients, reducing their effects on killing cancer cells. Chemoresistance can lead to a rapid recurrence of cancers and ultimately patient death. MDR may be induced by multiple mechanisms, which are associated with a complex process of multiple genes, factors, pathways, and multiple steps, and today the MDR-associated mechanisms are largely unknown. In this paper, from the aspects of protein-protein interactions, alternative splicing (AS) in pre-mRNA, non-coding RNA (ncRNA) mediation, genome mutations, variance in cell functions, and influence from the tumor microenvironment, we summarize the molecular mechanisms associated with MDR in cancers. In the end, prospects for the exploration of antitumor drugs that can reverse MDR are briefly discussed from the angle of drug systems with improved targeting properties, biocompatibility, availability, and other advantages.

Six MicroRNA Prognostic Models for Overall Survival of Lung Adenocarcinoma

Objective

The purpose of this study is to screen for microRNAs (miRNAs) associated with the prognosis of lung adenocarcinoma (LUAD) and to explore its prognosis and effects on the tumor microenvironment in patients with LUAD.

Methods

Gene expression data, miRNA expression data, and clinical data for two different databases, TCGA-LUAD and CPTAC-3 LUAD, were downloaded from the GDC database. The miRNA prognosis of LUAD was filtered by the Cox proportional hazard model and the Least Absolute Shrinkage and Selection Operator (LASSO) regression model. The performance of the model was validated by time-dependent receiver operating characteristics (ROC) curves. Possible biological processes associated with the miRNAs target gene were analyzed through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Finally, the prognostic model was scored by risk, divided into high- and low-risk groups by median, and the differences in the immersion level of 21 immune cells in the high- and low-risk groups were assessed. To gain a deeper understanding of the underlying mechanism behind the model, the two most important miRNAs in the model, miR-195-3p and miR-5571-5p, were selected for HPA database validation and ceRNA network construction.

Results

Of the 209 variance expressions identified in the screening analysis, 145 were upregulated and 64 were downregulated by miRNAs. The prognostic models of six miRNA genes were obtained: miR-195-3p, miR-5571-5p, miR-584-3p, miR-494-3p, miR-4664-3p, and miR-1293. These six genes were significantly associated with survival rates in LUAD patients. In particular, miR-1293, miR-195-3p, and miR-5571-5p are highly correlated with OS. The higher expression of miR-195-3p and miR-5571-5p, the better survival of LUAD OS is, and these two miRNA expressions contribute the most to the model. Finally, after sorting the risk scores calculated from low to high using the prognostic model, the patients with higher scores had shorter survival time and higher frequency of death, and there were significant differences in the immersion levels of 21 immune cells in the high- and low-risk groups. ceRNA network analysis found that TM9SF3 was regulated by miR-195-3p and was highly expressed in the tissues of LUAD patients, and the prognosis of the patients was poor.

Conclusions

miR-195-3p, miR-5571-5p, miR-584-3p, miR-494-3p, miR-4664-3p, and miR-1293 may be used as new biomarkers for prognosis prediction of LUAD. Our results also identified a lncRNA MEG3/miR-195-3p/RAB1A/TM9SF3 regulatory axis, which may also play an important role in the progression of LUAD. Further study needs to be conducted to verify this result.

Epicardial HDAC3 Promotes Myocardial Growth Through a Novel MicroRNA Pathway

BACKGROUND

Establishment of the myocardial wall requires proper growth cues from nonmyocardial tissues. During heart development, the epicardium and epicardium-derived cells instruct myocardial growth by secreting essential factors including FGF (fibroblast growth factor) 9 and IGF (insulin-like growth factor) 2. However, it is poorly understood how the epicardial secreted factors are regulated, in particular by chromatin modifications for myocardial formation. The current study is to investigate whether and how HDAC (histone deacetylase) 3 in the developing epicardium regulates myocardial growth.

METHODS

Various cellular and mouse models in conjunction with biochemical and molecular tools were employed to study the role of HDAC3 in the developing epicardium.

RESULTS

We deleted Hdac3 in the developing murine epicardium, and mutant hearts showed ventricular myocardial wall hypoplasia with reduction of epicardium-derived cells. The cultured embryonic cardiomyocytes with supernatants from Hdac3 knockout (KO) mouse epicardial cells also showed decreased proliferation. Genome-wide transcriptomic analysis revealed that Fgf9 and Igf2 were significantly downregulated in Hdac3 KO mouse epicardial cells. We further found that Fgf9 and Igf2 expression is dependent on HDAC3 deacetylase activity. The supplementation of FGF9 or IGF2 can rescue the myocardial proliferation defects treated by Hdac3 KO supernatant. Mechanistically, we identified that microRNA (miR)-322 and miR-503 were upregulated in Hdac3 KO mouse epicardial cells and Hdac3 epicardial KO hearts. Overexpression of miR-322 or miR-503 repressed FGF9 and IGF2 expression, while knockdown of miR-322 or miR-503 restored FGF9 and IGF2 expression in Hdac3 KO mouse epicardial cells.

CONCLUSIONS

Our findings reveal a critical signaling pathway in which epicardial HDAC3 promotes compact myocardial growth by stimulating FGF9 and IGF2 through repressing miR-322 or miR-503, providing novel insights in elucidating the etiology of congenital heart defects and conceptual strategies to promote myocardial regeneration.

Non-coding RNAs: are they the protagonist or antagonist in the regulation of leukemia?

The idea of functional non-coding RNAs is taking precedence over the previous notion which believed that they only comprise the auxiliary and junk material of the genome. Newer technologies and studies have proven their importance in regulating and affecting several cellular processes. One such area of research wherein their importance has started to take light is in cancer research, particularly leukemia. Myeloid leukemia is a blood malignancy birthed from mutations in hematopoiesis that disable myeloid progenitor cells from proper differentiation. This review will compile the most recent findings regarding the effects of these regulatory non-coding RNAs on the two types of myeloid leukemia. In particular, the effects of circular RNAs, micro RNAs and long non-coding RNAs, on the pathogenesis and proliferation of Acute and Chronic myeloid leukemia will be revealed in a molecular, cellular and prognostic light. The mechanisms of proliferation, gene-to-gene interactions and possible therapeutic effects will also be discussed. Finally, an understanding of the overall "goodness" and "badness" of these non-coding RNAs will be summarised. This review hopes to provide a platform for easy access to data regarding the current non-coding RNAs in myeloid leukemia, for faster and easier research. Finally, the review will summarize a few key players that have protagonistic and antagonistic functions, and those that regulate multiple pathways in leukemia simultaneously.

Exosomal miRNA-223-3p as potential biomarkers in patients with cerebral small vessel disease cognitive impairment

BACKGROUND

Cerebrovascular disease is a common clinical illness. Many patients with cerebrovascular disease can be accompanied by cognitive impairment. The exosomal microRNA (miRNA)-223-3p is related to vascular endothelial injury, synaptic function, inflammatory response, and other mechanisms. In this study, we investigated the levels of plasma exosomal miRNA-223-3p in patients with cerebral small vessel disease (CSVD), in order to determine whether it could be used as a more accessible potential biomarker for the early diagnosis and treatment of CSVD. This study aimed to explore whether the development of cognitive impairment can be explained by differentially expressed miRNA-223-3p by detecting the level of miRNA-223-3p, which is abundant in peripheral blood exosomes related to cognitive impairment in CSVD.

METHODS

The three groups of participants included 40 patients with CSVD cognitive impairment (CSVDCI), 38 patients with CSVD, and 35 normal controls (NC). The real-time polymerase chain reaction (RT-PCR) was used to detect the expression level of blood exosomal miRNA-223-3p. In addition, we also studied the relationship between exosomal miRNA-223-3p and blood Hcy and C-reactive protein (CRP). Receiver-operating characteristic (ROC) curve analysis was used to evaluate the diagnostic efficacy of plasma exosomal miRNA-223-3p.

RESULTS

The expression of exosomal miRNA-223-3p in CSVD increased, and the expression of miRNA-223-3p increased significantly with the occurrence of cognitive impairment. Exosomal miRNA-223-3p was positively correlated with the expression levels of Hcy and CRP in the blood.

CONCLUSIONS

The expression of plasma exosomal miRNA-223-3p is associated with the development of cognitive impairment in patients with CSVD. It may be involved in the pathogenesis of CSVD and cognitive impairment, and can be used as a sensitive predictive biomarker.

Long non-coding RNA THRIL is upregulated in coronary heart disease and binds to microRNA-424 to upregulate TXNIP in mice

Cardiovascular disease, particularly coronary heart disease (CHD), is one of the diseases with the highest fatality. The close correlation between long non-coding RNAs (lncRNAs) and the occurrence and development of myocardial injury has been highlighted recently. This article mainly focused on the regulation of THRIL on myocardial injury caused by CHD in mice. After establishment of a mouse model with CHD, a lncRNA microarray analysis was performed on mouse myocardial tissues to detect differentially expressed lncRNAs, followed by RT-qPCR validation. CHD was induced in mice by high-fat diet feeding and THRIL was silenced using si-THRIL. The results showed that treating CHD mice with si-THRIL attenuated myocardial damage by restoring LVEF, LVFS, and HDL-C levels, while lowering HMI, LVMI, TC, TG, LDL-C, CK-MB, and cTnI levels. Meanwhile, mechanistical studies using bioinformatics prediction, dual-luciferase and subcellular fractionation assays revealed that THRIL bound to microRNA (miR)-424, inhibited miR-424 interaction with TXNIP and promoted TXNIP expression in the myocardial tissues. The cardioprotective effects of si-THRIL on mice were attenuated when miR-424 was downregulated. Moreover, TXNIP exerted its effects on myocardial injury by mediating the p53 pathway. Taken together, this study demonstrated that THRIL inhibition alleviates myocardial injury in CHD possibly through the miR-424/TXNIP/p53 axis.

The miR-424(322)/503 gene cluster regulates pro- versus anti-inflammatory skin DC subset differentiation by modulating TGF-β signaling

Transforming growth factor β (TGF-β) family ligands are key regulators of dendritic cell (DC) differentiation and activation. Epidermal Langerhans cells (LCs) require TGF-β family signaling for their differentiation, and canonical TGF-β1 signaling secures a non-activated LC state. LCs reportedly control skin inflammation and are replenished from peripheral blood monocytes, which also give rise to pro-inflammatory monocyte-derived DCs (moDCs). By studying mechanisms in inflammation, we previously screened LCs versus moDCs for differentially expressed microRNAs (miRNAs). This revealed that miR-424/503 is the most strongly inversely regulated (moDCs > LCs). We here demonstrate that miR-424/503 is induced during moDC differentiation and promotes moDC differentiation in human and mouse. Inversely, forced repression of miR-424 during moDC differentiation facilitates TGF-β1-dependent LC differentiation. Mechanistically, miR-424/503 deficiency in monocyte/DC precursors leads to the induction of TGF-β1 response genes critical for LC differentiation. Therefore, the miR-424/503 gene cluster plays a decisive role in anti-inflammatory LC versus pro-inflammatory moDC differentiation from monocytes.