MiR-486 promotes proliferation and suppresses apoptosis in myeloid cells by targeting Cebpa in vitro

The immunomodulatory role of exosomal microRNA networks in the crosstalk between tumor-associated myeloid-derived suppressor cells and tumor cells

Myeloid-derived suppressor cells (MDSCs) are considered a heterogeneous group of immature myeloid cells engaging in aggressive tumor progression and metastasis in the tumor microenvironment (TME) of patients diagnosed with cancer, through downregulation of anti-tumor immune responses. Exosomes are small vesicles carrying specific cargos, including proteins, lipids, and MicroRNA (miRNAs). Such exosomal miRNAs delivered by MDSCs and tumor cells are short noncoding RNAs mediating some of the immunosuppressive characteristics of MDSCs in the TME. However, when it comes to cancer diseases, how these miRNAs interact with MDSCs and encourage MDSCs differentiation and function need further investigations. In this review, we discuss MDSC-derived exosomal miRNAs and those derived from tumor cells (TDE) could modulate anti-tumor immunity and regulate the interaction between tumor cells and MDSCs in the TME. Afterward, we focus on dividing miRNAs, as an important substance interacting with MDSCs and tumor cells in the TME, into those have an immunosuppressive or stimulating effect not only on MDSCs expansion, differentiation, and suppressive function but also on tumor evasion.

Differential Effect of Extracellular Vesicles Derived from Plasmodium falciparum-Infected Red Blood Cells on Monocyte Polarization

Malaria is a life-threatening tropical arthropod-borne disease caused by Plasmodium spp. Monocytes are the primary immune cells to eliminate malaria-infected red blood cells. Thus, the monocyte's functions are one of the crucial factors in controlling parasite growth. It is reasoned that the activation or modulation of monocyte function by parasite products might dictate the rate of disease progression. Extracellular vesicles (EVs), microvesicles, and exosomes, released from infected red blood cells, mediate intercellular communication and control the recipient cell function. This study aimed to investigate the physical characteristics of EVs derived from culture-adapted P. falciparum isolates (Pf-EVs) from different clinical malaria outcomes and their impact on monocyte polarization. The results showed that all P. falciparum strains released similar amounts of EVs with some variation in size characteristics. The effect of Pf-EV stimulation on M1/M2 monocyte polarization revealed a more pronounced effect on CD14⁺CD16⁺ intermediate monocytes than the CD14⁺CD16^- classical monocytes with a marked induction of Pf-EVs from a severe malaria strain. However, no difference in the levels of microRNAs (miR), miR-451a, miR-486, and miR-92a among Pf-EVs derived from virulent and nonvirulent strains was found, suggesting that miR in Pf-EVs might not be a significant factor in driving M2-like monocyte polarization. Future studies on other biomolecules in Pf-EVs derived from the P. falciparum strain with high virulence that induce M2-like polarization are therefore recommended.

Interaction Between microRNAs and Myeloid-Derived Suppressor Cells in Tumor Microenvironment

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells generated during a series of pathologic conditions including cancer. MicroRNA (miRNA) has been considered as a regulator in different tumor microenvironments. Recent studies have begun to unravel the crosstalk between miRNAs and MDSCs. The knowledge of the effect of both miRNAs and MDSCs in tumor may improve our understanding of the tumor immune escape and metastasis. The miRNAs target cellular signal pathways to promote or inhibit the function of MDSCs. On the other hand, MDSCs transfer bioinformation through exosomes containing miRNAs. In this review, we summarized and discussed the bidirectional regulation between miRNAs and MDSCs in the tumor microenvironment.

MicroRNAs/LncRNAs Modulate MDSCs in Tumor Microenvironment

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of immature cells derived from bone marrow that play critical immunosuppressive functions in the tumor microenvironment (TME), promoting cancer progression. According to base length, Non-coding RNAs (ncRNAs) are mainly divided into: microRNAs (miRNAs), lncRNAs, snRNAs and CircRNAs. Both miRNA and lncRNA are transcribed by RNA polymerase II, and they play an important role in gene expression under both physiological and pathological conditions. The increasing data have shown that MiRNAs/LncRNAs regulate MDSCs within TME, becoming one of potential breakthrough points at the investigation and treatment of cancer. Therefore, we summarize how miRNAs/lncRNAs mediate the differentiation, expansion and immunosuppressive function of tumor MDSCs in TME. We will then focus on the regulatory mechanisms of exosomal MicroRNAs/LncRNAs on tumor MDSCs. Finally, we will discuss how the interaction of miRNAs/lncRNAs modulates tumor MDSCs.

MicroRNAs as Predictors of Future Uterine Malignancy in Endometrial Hyperplasia without Atypia

The histological criteria for classifying endometrial hyperplasia (EH) are based on architectural crowding and nuclear atypia; however, diagnostic agreement among pathologists is poor. We investigated molecular biomarkers of endometrial cancer (EC) risk in women with simple hyperplasia or complex hyperplasia without atypia (SH/CH-nonA). Forty-nine patients with EC preceded by SH/CH-nonA were identified, of which 23 were excluded (15 with complex atypical hyperplasia (CAH), six not consenting, one with a diagnosis < 6 months prior, and one lost to follow-up). The EH tissues of these patients were compared with those of patients with SH/CH-nonA that did not progress to EC (control) through microRNA (miRNA) array analysis, and the results were verified in an expanded cohort through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). MiRNA arrays analyses revealed 20 miRNAs that differed significantly (p < 0.05, fold change > 4) between the control (n = 12) and case (n = 6) patients. Multiplex RT-qPCR for the 20 miRNAs in the expanded cohort (94 control and 25 case patients) led to the validation of miR-30a-3p (p = 0.0009), miR-141 (p < 0.0001), miR-200a (p < 0.0001), and miR-200b (p < 0.0001) as relevant biomarkers, among which miR-141, miR-200a, and miR-200b regulate the expression of phosphatase and tensin homolog (PTEN). For the prediction of EC, the area under the curve for miR-30a-3p, miR-141, miR-200a, and miR-200b was 0.623, 0.754, 0.783, and 0.704, respectively. The percentage of complete PTEN loss was significantly higher in the case group than in the control group (24% vs. 0%, p < 0.001, Fisher’s exact test). A combination of complete PTEN loss and miR-200a provided optimal prediction performance (sensitivity = 0.760; specificity = 1.000; positive predictive value = 1.000; negative predictive value = 0.937; accuracy = 0.947). MiR-30a-3p, miR-141, miR-200a, miR-200b, and complete PTEN loss may be useful tissue biomarkers for predicting EC risk among patients with SH/CH-nonA.

Role of FUS-CHOP in Myxoid Liposarcoma via miR-486/CDK4 Axis

This study aimed to explore the roles and relationship between FUsed in Sarcoma (FUS)-C/EBP HOmologous Protein (CHOP), microRNA (miR)-486 and cyclin dependent kinase 4 (CDK4) in myxoid liposarcoma, and determined whether FUS-CHOP can regulate proliferation and apoptosis of myxoid liposarcoma cells by regulating miR-486/CDK4 axis. The levels of miR-486, CDK4 and FUS-CHOP in myxoid liposarcoma samples/adjacent normal muscle tissues and myxoid liposarcoma/human adipose-derived stem cell line were evaluated using reverse transcription-quantitative polymerase chain reaction and western blotting. Cell proliferation and apoptosis were performed using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and flow cytometry, respectively. Furthermore, the apoptosis-related proteins were determined using Western blot assay. We found that miR-486 was down-regulated, FUS-CHOP and CDK4 were up-regulated in myxoid liposarcoma tissues and myxoid liposarcoma cell lines. Moreover, FUS-CHOP-siRNA distinctly suppressed FUS-CHOP level and increased miR-486 levels in 1955/91 cells. Our results demonstrated that knockdown of FUS-CHOP by siRNA inhibited 1955/91 growth, promoted cell apoptosis and enhanced cleaved Caspase3 protein expression. However, all these data were reversed by miR-486 inhibitor. Similarly, compared to mimic control, miR-486 mimic markedly reduced 1955/91 cells growth, induced cell apoptosis and fortified cleaved Caspase3 level, while these results were abolished by CDK4-plasmid. Collectively, our observations clearly suggested that FUS-CHOP regulated myxoid liposarcoma cell proliferation and apoptosis by the regulation of miR-486/CDK4 axis, indicating the potential use of FUS-CHOP-siRNA as a promising therapy for myxoid liposarcoma.

Abnormal Expression of microRNA-296-3p in Type 2 Diabetes Patients and its Role in Pancreatic β-Cells Function by Targeting Tensin Homolog Deleted on Chromosome Ten

Diabetes mellitus (DM), a familiar disease, is characterized by high blood glucose levels owing to insulin deficiency. Researches have suggested that the incidence rate of diabetes is increasing and it has become an important global epidemic. The type 2 diabetes mellitus (T2DM) is featured with pancreatic β-cell loss and lack of insulin release. Nevertheless, the therapeutic methods that was helpful to improve pancreatic β-cell damage still unclear. Previous report have revealed that tensin homolog deleted on chromosome ten (PTEN) was remarkably enhanced in serum of patients with T2DM, and the lack of PTEN may prevent function deficiency of pancreatic β-cells in DM. However, the underlying mechanisms are rarely illustrated. Our purpose in this report was to illustrated the roles and potential mechanism of microRNA-296-3p (miR-296-3p) in uric acid (UA)-induced pancreatic β-cell injury. The direct target of miR-296-3p was predicted and verified by dual-luciferase reporter system and TargetScan assay. Moreover, Min6 cells were induced by 5 mg/dl UA and the cell proliferation, apoptosis, and insulin release were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry and glucose-stimulated insulin secretion (GSIS), respectively. Quantitative reverse transcription PCR (qRT-PCR) and western blot assay were adopted to analyze the levels of miR-296-3p, PTEN and apoptosis-related proteins. TargetScan and Dual-luciferase reporter system confirmed that PTEN directly target miR-296-3p. MiR-296-3p was downregulated in UA-induced Min6 cells and the serum of type 2 diabetes patients, while PTEN was upregulated in UA-induced Min6 cells. Upregulation of miR-296-3p by mimic dramatically promoted miR-296-3p level and decreased PTEN level. Besides, PTEN was over-expressed after PTEN-plasmid transfection. UA treatment prominently decreased cell viability, promoted apoptotic cells, enhanced Bax levels, declined Bcl-2 level as well as decreased insulin release in Min6 cells. MiR-296-3p mimic significantly alleviated UA-induced pancreatic β-cells dysfunction, and PTEN-plasmid eliminated the protective effect of miR-296-3p on insulin release, cell viability, and apoptosis of pancreatic β-cells in UA-stimulated Min6 cells. In summary, our findings revealed that upregulation of miR-296-3p protected pancreatic β-cells functions against UA-induced dysfunction by targeting PTEN, which provides a novel agent for type 2 diabetes treatment.

Tumor Immune Microenvironment and Its Related miRNAs in Tumor Progression

MiRNA is a type of small non-coding RNA, by regulating downstream gene expression that affects the progression of multiple diseases, especially cancer. MiRNA can participate in the biological processes of tumor, including proliferation, invasion and escape, and exhibit tumor enhancement or inhibition. The tumor immune microenvironment contains numerous immune cells. These cells include lymphocytes with tumor suppressor effects such as CD8+ T cells and natural killer cells, as well as some tumor-promoting cells with immunosuppressive functions, such as regulatory T cells and myeloid-derived suppressor cells. MiRNA can affect the tumor immune microenvironment by regulating the function of immune cells, which in turn modulates the progression of tumor cells. Investigating the role of miRNA in regulating the tumor immune microenvironment will help elucidate the specific mechanisms of interaction between immune cells and tumor cells, and may facilitate the use of miRNA as a predictor of immune disorders in tumor progression. This review summarizes the multifarious roles of miRNA in tumor progression through regulation of the tumor immune microenvironment, and provides guidance for the development of miRNA drugs to treat tumors and for the use of miRNA as an auxiliary means in tumor immunotherapy.

Sertoli cell-derived exosomal MicroRNA-486-5p regulates differentiation of spermatogonial stem cell through PTEN in mice

Self‐renewal and differentiation of spermatogonial stem cell (SSC) are critical for male fertility and reproduction, both of which are highly regulated by testicular microenvironment. Exosomal miRNAs have emerged as new components in intercellular communication. However, their roles in the differentiation of SSC remain unclear. Here, we observed miR‐486‐5p enriched in Sertoli cell and Sertoli cell‐derived exosomes. The exosomes mediate the transfer of miR‐486‐5p from Sertoli cells to SSCs. Exosomes release miR‐486‐5p, thus up‐regulate expression of Stra8 (stimulated by retinoic acid 8) and promote differentiation of SSC. And PTEN was identified as a target of miR‐486‐5p. Overexpression of miR‐486‐5p in SSCs down‐regulates PTEN expression, which up‐regulates the expression of STRA8 and SYCP3, promotes SSCs differentiation. In addition, blocking the exosome‐mediated transfer of miR‐486‐5p inhibits differentiation of SSC. Our findings demonstrate that miR‐486‐5p acts as a communication molecule between Sertoli cells and SSCs in modulating differentiation of SSCs. This provides a new insight on molecular mechanisms that regulates SSC differentiation and a basis for the diagnosis, treatment, and prevention of male infertility.

The role of non-coding genome in the behavior of infiltrated myeloid-derived suppressor cells in tumor microenvironment; a perspective and state-of-the-art in cancer targeted therapy

Cancer is one of the healthcare problems that affect many communities around the world. Many factors contribute to cancer development. Besides, these factors are counted as the main impediment in cancer immunotherapy. Myeloid-derived suppressor cells (MDSCs) are one of these impediments. MDSCs inhibit the immune responses through various mechanisms such as inhibitory cytokine release and nitric oxide metabolite production. Several factors are involved in forming these cells, including tumor secreted cytokine and chemokines, transcription factors, and non-coding RNA. In the meantime, micro-RNAs (miRNAs) and long non-coding RNAs (lncRNAs) are the vital gene regulatory elements that affect gene expression. In this study, we are going to discuss the role of miRNAs and lncRNAs in MDSCs development in a cancer situation. It is hoped that miRNA and lncRNAs targeting may prevent the growth and development of these inhibitory cells in the cancer environment.

circ_001653 Silencing Promotes the Proliferation and ECM Synthesis of NPCs in IDD by Downregulating miR-486-3p-Mediated CEMIP

Functional changes of nucleus pulposus cells (NPCs) are considered to be the initiating factors of intervertebral disc degeneration (IDD). In this study, we investigated whether circular RNA homo sapiens (hsa)_circ_001653 (circ_001653) could bind to microRNA-486-3p (miR-486-3p) to regulate the biological properties of NPCs and the synthesis of extracellular matrix (ECM) in IDD. Initially, circ_001653 was highly expressed in isolated NPCs and degenerative NP tissues in close relation to the severity of IDD. To evaluate the effects of circ_001653 on cellular processes, we performed experiments in vitro and in vivo with altered expression of circ_001653 and miR-486-3p. An increased expression of circ_001653 in the NPCs and the degenerative NP tissues was directly associated with elevated apoptosis and an imbalance between anabolic and catabolic factors of the ECM. miR-486-3p regulated NPC proliferation and inhibited the expression of CEMIP, the cell migration-inducing hyaluronan binding protein. circ_001653 regulated miR-486-3p expression, functioning in NPCs to upregulate CEMIP, whereas circ_001653 silencing alleviated IDD in the mouse model. Altogether, circ_001653 downregulation could potentially alleviate NPC apoptosis and the metabolic imbalance of the ECM through the miR-486-3p/CEMIP axis. These mechanistic insights may present new therapeutic targets for the treatment of IDD.

CXCR2 expression on granulocyte and macrophage progenitors under tumor conditions contributes to mo-MDSC generation via SAP18/ERK/STAT3

Myeloid-derived suppressor cells (MDSCs) comprise a critical component of the tumor environment and CXCR2 reportedly plays a key role in the pathophysiology of various inflammatory diseases. Here, CXCR2 expression on granulocyte and macrophage progenitor cells (GMPs) was found to participate in myeloid cell differentiation within the tumor environment. In CXCR2-deficient tumor-bearing mice, GMPs exhibited fewer macrophage and dendritic cell progenitor cells than wild-type tumor-bearing mice, thereby decreasing monocytic MDSCs (mo-MDSCs) expansion. CXCR2 deficiency increased SAP18 expression in tumor-bearing mice, which reduced STAT3 phosphorylation through restraining ERK1/2 activation. Our findings reveal a critical role for CXCR2 in regulating hematopoietic progenitor cell differentiation under tumor conditions, and SAP18 is a key negative regulator in this process. Thus, inhibiting CXCR2 expression may alter the tumor microenvironment and attenuate tumor progression.

MicroRNA-3666 inhibits lung cancer cell proliferation, migration, and invasiveness by targeting BPTF

A previous study by our group indicted that overexpression of bromodomain PHD-finger transcription factor (BPTF) occurs in lung adenocarcinoma, and is closely associated with advanced clinical stage, higher numbers of metastatic lymph nodes, the occurrence of distant metastasis, low histological grade, and poor prognosis. Down-regulation of BPTF inhibited lung adenocarcinoma cell proliferation and promoted lung adenocarcinoma cell apoptosis. The purpose of this study is to identify valuable microRNAs (miRNAs) that target BPTF to modulate lung adenocarcinoma cell proliferation. In our results, we found that miR-3666 was notably reduced in lung adenocarcinoma tissues and cell lines. Using an miR-3666 mimic, we discovered that cell proliferation, migration, and invasiveness were suppressed by miR-3666 overexpression, but these were all enhanced when the expression of miR-3666 was reduced. Moreover, bioinformatics analysis using the TargetScan database and miRanda software suggested a putative target site in BPTF 3′-UTR. Furthermore, using a luciferase reporter assay, we verified that miR-3666 directly targets the 3′-UTR of BPTF. Using Western blot we discovered that overexpression of miR-3666 negatively regulates the protein expression of BPTF. Finally, we identified that the PI3K–AKT and epilthelial–mesenchymal transition (EMT) signaling pathways were inhibited by miR-3666 overexpression in lung cancer cells. In conclusion, our data indicate that miR-3666 could play an essential role in cell proliferation, migration, and invasiveness by targeting BPTF and partly inhibiting the PI3K–AKT and EMT signaling pathways in human lung cancers.

miRNA-301b-3p accelerates migration and invasion of high-grade ovarian serous tumor via targeting CPEB3/EGFR axis

High-grade ovarian serous carcinoma (HGS-OvCa), a type of ovarian cancer with poor prognosis due to distant metastasis, is urgently in need of new therapeutic targets. microRNAs (miRNAs), a class of small noncoding RNAs, perform significant roles in tumor progression. Mounting evidence has revealed the aberrant expression of miRNA in various cancers, one of which is HGS-OvCa. Present study planned to investigate that miRNA-301b-3p accelerates migration and invasion of high-grade ovarian serous tumor via targeting CPEB3/EGFR axis. Upregulation of miR-301b-3p was uncovered in HGS-OvCa tissues and cell lines, and was identified to be associated with metastasis. The Kaplan-Meier analysis confirmed the association of miR-301b-3p with poor prognosis of HGS-OvCa patients. Transwell assay validated the oncogenic effect of miR-301b-3p on migration and invasion of HGS-OvCa cells. Cytoplasmic polyadenylation element binding protein 3 (CPEB3) was then identified as a target of miR-301b-3p. It was also discovered that CPEB3 was downregulated in HGS-OvCa tissues and cell lines. The Spearman correlation curve presented the negative correlation of CPEB3 expression with miR-301b-3p. Furthermore, rescue assays proved that miRNA-301b-3p regulated the invasion and migration through CPEB3. Western blot and qRT-PCR analysis showed that miRNA-301b-3p induced epidermal growth factor receptor and downstream metastasis-related proteins, p38, and extracellular signal-regulated kinase 1/2 (ERK1/2), through CPEB3. To be concluded, these results indicated that miRNA-301b-3p accelerated migration and invasion of high-grade ovarian serous tumor via targeting CPEB3/EGFR axis.

MiR-486 promotes proliferation and suppresses apoptosis in myeloid cells by targeting Cebpa in vitro

The monocytic MDSC (M‐MDSC) is one of the major types of MDSCs, which play important roles in suppression of antitumor immunity. However, the mechanisms underlying how M‐MDSCs so heavily accumulate in patients with cancer are still poorly understood. The purpose of this study was to identify miRNAs that regulate the proliferation and differentiation of M‐MDSCs. Microarray analysis was performed to identify differentially expressed miRNAs between tumor‐induced M‐MDSCs (TM‐MDSCs) and their counterparts from tumor‐free mice. The miRNAs and their target genes that regulate the proliferation and differentiation of myeloid cells were predicted by bioinformatics analysis and validated by RT‐qPCR. Luciferase reporter assays were used to analyze the relationships between miRNAs and target genes. Overexpression of candidate miRNAs and target genes in myeloid cells was conducted to verify their functions in cell proliferation, differentiation, and apoptosis. Our data showed that miR‐486 was overexpressed in TM‐MDSCs. Cebpa was predicted to be one of the target genes of miR‐486 that regulates the proliferation of myeloid cells. Expression of Cebpa was inversely correlated with miR‐486 in TM‐MDSCs, and we found that overexpression of miR‐486 suppressed the expression of Cebpa in both 293T cells determined by luciferase reporter assays and in myeloid cells determined by RT‐qPCR. Overexpression of miR‐486 promoted proliferation and suppressed apoptosis in myeloid cells, as opposed to overexpression of Cebpa, which promoted the opposing phenotype. Overexpression of either miR‐486 or Cebpa inhibited differentiation of myeloid cells. This study indicates that miR‐486 promotes proliferation and suppresses apoptosis in myeloid cells by targeting Cebpa in vitro, suggesting that miR‐486 and Cebpa might be involved in the expansion of TM‐MDSCs in tumor‐bearing mice.