Sperm-borne microRNA-34c regulates maternal mRNA degradation and preimplantation embryonic development in mice

BACKGROUND

Studies have shown that sperm-borne microRNAs (miRNAs) are involved in mammalian preimplantation embryonic development. In humans, spermatozoan miR-34c levels are correlated with in vitro fertilization outcomes, such as embryo quality and the clinical pregnancy and live birth rates. In rabbits and cows, miR-34c improves the developmental competence of embryos generated by somatic cell nuclear transfer. However, the mechanisms underlying the regulation of embryonic development by miR-34c remain unknown.

METHODS

Female C57BL/6 mice (6-8 weeks old) were superovulated, and pronucleated zygotes were collected and microinjected with an miR-34c inhibitor or a negative-control RNA. The embryonic development of the microinjected zygotes was evaluated, and the messenger RNA (mRNA) expression profiles of the embryos at the two-cell, four-cell and blastocyst stages (five embryos per group) were determined by RNA sequencing analysis. Gene expression levels were verified by reverse transcription-quantitative polymerase chain reaction. Cluster analysis and heat map visualization were performed to detect differentially expressed mRNAs. Pathway and process enrichment analyses were performed using ontology resources. Differentially expressed mRNAs were systematically analyzed using the Search Tool for the Retrieval of Interacting Genes/Proteins database to determine their biological functions.

RESULTS

Embryonic developmental potential was significantly reduced in zygotes microinjected with the miR-34c inhibitor compared with those microinjected with a negative-control RNA. Two-cell stage embryos microinjected with an miR-34c inhibitor presented altered transcriptomic profiles, with upregulated expression of maternal miR-34c target mRNAs and classical maternal mRNAs. Differentially expressed transcripts were mainly of genes associated with lipid metabolism and cellular membrane function at the two-cell stage, with cell-cycle phase transition and energy metabolism at the four-cell stage; and with vesicle organization, lipid biosynthetic process and endomembrane system organization at the blastocyst stage. We also showed that genes related to preimplantation embryonic development, including Alkbh4, Sp1, Mapk14, Sin3a, Sdc1 and Laptm4b, were significantly downregulated after microinjection of an miR-34c inhibitor.

CONCLUSIONS

Sperm-borne miR-34c may regulate preimplantation embryonic development by affecting multiple biological processes, such as maternal mRNA degradation, cellular metabolism, cell proliferation and blastocyst implantation. Our data demonstrate the importance of sperm-derived miRNAs in the development of preimplantation embryos.

Extracellular vesicles derived from hypoxia-preconditioned bone marrow mesenchymal stem cells ameliorate lower limb ischemia by delivering miR-34c

Hypoxic mesenchymal stem cell-derived extracellular vesicles (EVs) have been suggested as a promising therapy for various diseases. This study aims to determine the effect of EVs derived from bone marrow mesenchymal stem cells (BMMSCs) under hypoxia on lower limb ischemia and the underlying mechanism. Human BMMSCs were subjected to hypoxia or normoxia followed by the isolation of EVs. Nanoparticle trafficking analysis (NTA), transmission electron microscopy (TEM), and Western Blotting using corresponding markers were performed to confirm the EVs. The EVs from BMMSCs under hypoxia condition (Hyp-EVs) or normoxia condition (Nor-EVs) were subjected to hindlimb ischemia (HI) mice. MiR-34c expression in BMMSCs and BMMSC-EVs was detected. The role of miR-34c in regulating M2 macrophage polarization, as well as the target of miR-34c, were explored. HI mice with Hyp-EV treatment, as compared to the Nor-EV or the PBS group, had better blood flow and higher capillary density. MiR-34c expression was increased in BMMSCs, BMMSC-EVs, and the adductor muscle of HI mice. Hyp-EVs promoted the M2 macrophage polarization and anti-inflammatory cytokine production, and enhanced the blood flow and capillary density in HI mice, while the knockdown of miR-34c partly reversed these effects. PTEN is a target of miR-34c, and the PTEN silencing facilitated M2 macrophage polarization, whereas the inhibition of AKT signaling partly abolished the effect. Hyp-EVs promoted M2 macrophage polarization by delivering miR-34c via PTEN/AKT pathway, which could be a promising therapeutic strategy to ameliorate lower limb ischemia.

MiR-34b/c play a role in early sex differentiation of Amur sturgeon, Acipenser schrenckii

Background

Sex differentiation can be viewed as a controlled regulatory balance between sex differentiation-related mRNAs and post-transcriptional mechanisms mediated by non-coding RNAs. In mammals, increasing evidence has been reported regarding the importance of gonad-specific microRNAs (miRNAs) in sex differentiation. Although many fishes express a large number of gonadal miRNAs, the effects of these sex-biased miRNAs on sex differentiation in teleost fish remain unknown. Previous studies have shown the exclusive and sexually dimorphic expression of miR-34b/c in the gonads of the Amur sturgeon (Acipenser schrenckii), suggesting its potential role in the sex differentiation process.

Results

Using quantitative real-time PCR (qPCR), we observed that miR-34b/c showed consistent spatiotemporal expression patterns; the expression levels significantly increased during early sex differentiation. Using in situ hybridization, miR-34c was found to be located in the germ cells. In primary germ cells in vitro, the group subjected to overexpression and inhibition of miR-34c showed significantly higher proliferation ability and lower apoptosis, respectively, compared to the corresponding control group. Luciferase reporter assays using the ar-3′UTR-psiCHECK-2 luciferase vector suggested a targeted regulatory interaction between miR-34b/c and the 3′UTR of the androgen receptor (ar) mRNA. Furthermore, miR-34b/c and ar showed negative expression patterns during early sex differentiation. Additionally, a negative feedback regulation pattern was observed between foxl2 expression in the ovaries and amh and sox9 expression in the testes during early sex differentiation.

Conclusions

This study sheds new light on the roles of miR-34b/c in gonad development of Amur sturgeon, and provides the first comprehensive evidence that the gonad-predominant microRNAs may have a major role in sex differentiation in teleost fish.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12983-022-00469-6.

Protective effect of miR-34c antagomir against STZ-induced memory impairment by targeting mTOR and PSD-95 in the hippocampus of rats

After long times of ongoing research, still there is no appropriate cure for Alzheimer's disease (AD). Recently, epigenetic alterations, particularly miRNA, have gotten attention in AD research. Among various miRNA, miR-34c has been addressed to be elevated in the brain of AD patients, however, its exact role and downstream mechanisms have not been elucidated yet. This study aimed to investigate the therapeutic potential of miR-34c antagomir on cognitive dysfunction induced by streptozocin (STZ), considering postsynaptic density protein 95 (PSD-95) and mammalian target of rapamycin expression (mTOR). Forty rats were cannulated intraventricularly under deep anesthesia using stereotaxic apparatus and divided into five groups: saline + saline, STZ + saline, STZ + miR-34c antagomir, STZ + lipofectamine, and STZ + scrambled, and received the related treatments for two weeks. At the end of the treatments, spatial memory and locomotor activity were assessed by Morris water maze (MWM), and open fields, respectively. Finally, PSD-95 and mTOR levels were measured by quantitative real-time PCR (qPCR) and western blotting on hippocampal samples. Results showed that miR-34c antagomir markedly ameliorated spatial learning and memory deficits induced by STZ, and significantly enhanced PSD-95 and mTOR levels in the hippocampus. In conclusion, miR-34c antagomir may be considered as a promising novel therapeutic target for AD patients.

Trehalose Attenuates Learning and Memory Impairments in Aged Rats via Overexpression of miR-181c

MicroRNAs have been recognized as important regulators of the aging process. Trehalose, a natural disaccharide, displays protective effects against neuronal impairment through several mechanisms. However, little is known about the interactive effects of aging and trehalose on behavioral function and underlying miRNA expression patterns in the hippocampus of young and old rats. Male Wistar rats were divided into four groups. Two groups of aged (24 months) and young (4 months) rats were administered 2% trehalose solution for 30 days. Two other groups of aged and young rats received regular tap water. At the end of treatment, rats were assessed for cognitive behavior using the Morris water maze test. The expression level of miR-181c and mir-34c was also measured by qRT-PCR. We found that trehalose treatment reduced learning and memory impairment in old rats compared to control old animals (p < 0.05). In contrast, cognitive performance was not significantly improved in trehalose-treated young rats in comparison with young controls (p > 0.05). We also showed that the expression level of miR-181c was significantly increased in trehalose-treated rats (p < 0.01). However, analysis of miR-34c expression level indicated no significant difference between trehalose-treated old rats and non-treated old animals (p > 0.05). Our results indicated that trehalose treatment improved learning and memory function in aged rats by targeting miR-181c. Therefore, trehalose administration may provide a therapeutic strategy to ameliorate age-associated cognitive impairment.

Protective Role of miR-34c in Hypoxia by Activating Autophagy through BCL2 Repression

Hypoxia leads to significant cellular stress that has diverse pathological consequences such as cardiovascular diseases and cancers. MicroRNAs (miRNAs) are one of regulators of the adaptive pathway in hypoxia. We identified a hypoxia-induced miRNA, miR-34c, that was significantly upregulated in hypoxic human umbilical cord vein endothelial cells (HUVECs) and in murine blood vessels on day 3 of hindlimb ischemia (HLI). miR-34c directly inhibited BCL2 expression, acting as a toggle switch between apoptosis and autophagy in vitro and in vivo. BCL2 repression by miR-34c activated autophagy, which was evaluated by the expression of LC3-II. Overexpression of miR-34c inhibited apoptosis in HUVEC as well as in a murine model of HLI, and increased cell viability in HUVEC. Importantly, the number of viable cells in the blood vessels following HLI was increased by miR-34c overexpression. Collectively, our findings show that miR-34c plays a protective role in hypoxia, suggesting a novel therapeutic target for hypoxic and ischemic diseases in the blood vessels.

Role of autophagy and evaluation the effects of microRNAs 214, 132, 34c and prorenin receptor in a rat model of focal segmental glomerulosclerosis

AIMS

Focal segmental glomerulosclerosis (FSGS) is the common cause of chronic renal disease worldwide. Although there are many etiologic factors which have common theme of podocyte injury conclusive etiology is not clearly understood. In this study, we aimed to explore the role of autophagy in the pathogenesis of podocyte injury, which is the key point in disease progression, and the roles of intrarenal microRNAs and the prorenin receptor (PRR) in the 5/6 nephrectomy and adriamycin nephropathy models of FSGS.

MAIN METHODS

For experimental FSGS model, 5/6 nephrectomy and adriamycin nephropathy models were created and characterized in adult Sprague Dawley rats. Microarray analysis was performed on FSGS and control groups that was confirmed by q-RT-PCR. Beclin1, LC3B, PRR, ATG7 and ATG5 expression were evaluated by western blotting and immunohistochemistry. Also, Beclin1 and PRR expression were measured by ELISA. Glomerular podocyte isolation was performed and autophagic activity was evaluated in podocytes before and after transfection with miRNA mimic and antagonists.

KEY FINDINGS

Glomerular expression of Beclin1, LC3B, PRR, ATG7 and ATG5 were significantly lower in the 5/6 nephrectomy than adriamycin nephropathy group and in both groups lower when compared to control groups. Western blot results were consistent with immunohistochemical data. Electron microscopy revealed signs of impaired autophagy in FSGS. Autophagic activity decreased significantly after miR-214, miR-132 and miR-34c mimics and increased after transfection with antagonists.

SIGNIFICANCE

These results showed that the role of autophagic activity and decreased expression of PRR in FSGS pathogenesis and miR-34c, miR-132 and miR-214 could be a potential treatment strategy by regulating autophagy.

MiRNA-34c Regulates Bovine Sertoli Cell Proliferation, Gene Expression, and Apoptosis by Targeting the AXL Gene

Simple Summary

Fertility is one of the essential reproduction traits of bulls, and accurate prediction of fertility potential using a semen sample from a donor bull for artificial insemination is crucial to achieve consistently high reproductive efficiency. Somatic cells, such as Sertoli cells and Leydig cells, are important in testis formation and provide a nurturing and regulatory environment for spermatogenesis. Furthermore, it was suggested that non-coding RNAs, such as microRNAs, long non-coding RNAs, circular RNAs, and Piwi-interacting RNA, function as important regulators of gene expression at post-transcriptional level in spermatogenesis. In this study, microRNA-34c was verified to specifically regulate the AXL gene by targeting a sequence in the 3’ UTR; miRNA-34c can also influence the proliferation, apoptosis, and relative abundance of the transcript of male-reproduction-related genes. Therefore, microRNA-34c can be considered an essential regulator in the process of bull spermatogenesis. These results identify a key microRNA and functional genes in the process of cattle male reproduction, providing useful information for future marker-assisted selection of bulls with excellent sperm quality.

Abstract

MicroRNAs (miRNAs) play significant roles in mammalian spermatogenesis. Sertoli cells can provide a stable microenvironment and nutritional factors for germ cells, thus playing a vital role in spermatogenesis. However, few studies elucidate the regulation of bovine testicular Sertoli cells by miRNAs. Here, we have reported that miRNA-34c (miR-34c) regulates proliferation, apoptosis, and relative transcripts abundance gene in bovine Sertoli cells. In bovine Sertoli cells, overexpression of miR-34c inhibited proliferation and relative abundance of gene transcripts while promoting apoptosis of Sertoli cells, and the effects were the opposite when miR-34c was knocked down. Receptor tyrosine kinase (AXL) was identified as a direct target gene of miR-34c in Sertoli cells, validated by analysis of the relative abundance of AXL transcript and dual-luciferase reporter assay. The relative abundance of the transcript of genes related to male reproduction in Sertoli cells was changed after the AXL gene was overexpressed, as demonstrated by the RT2 Profiler PCR Array results. In summary, miR-34c specifically regulated the AXL gene by targeting a sequence in the 3′-UTR, which could influence proliferation, apoptosis, and relative abundance of the transcript of male reproduction-related genes. Therefore, miR-34c could be considered an essential regulator in the process of bull spermatogenesis.

Downregulation of tumor-derived exosomal miR-34c induces cancer-associated fibroblast activation to promote cholangiocarcinoma progress

Background

This study aimed to investigate the exact regulatory mechanisms of exosomal miR-34c in mediating communication between cholangiocarcinoma cells and fibroblasts.

Methods

Exosomes were isolated from HuCCT-1 and HIBEC cells using differential ultracentrifugation and identified by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) method. Real-time quantitative PCR (qRT-PCR) and western blotting analyses were performed to assess the levels of pro-inflammatory factors, and fibroblast-related proteins and Wnt-linked signaling pathway proteins, respectively. Exosome-tracking was performed with confocal microscopy. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and Transwell assays were used to measure cell proliferation and migration, respectively. Further, the oncogenicity of cholangiocarcinoma cells was analyzed in nude mice transplanted tumor model.

Results

The analysis suggested that the expression of miR-34c was decreased in exosomes from HuCCT-1 cells. Moreover, miR-34c in exosomes mediated fibroblast activation by directly targeting WNT1. Additionally, cancer-associated fibroblasts (CAFs) activated by downregulation of exosomal miR-34c promoted cholangiocarcinoma progression.

Conclusions

Thus, miR-34c in exosomes was found to be a key player in regulating intercellular communication between tumor cells and fibroblasts.

Conditioned Medium of Bone Marrow Mesenchymal Stem Cells Involved in Acute Lung Injury by Regulating Epithelial Sodium Channels via miR-34c

Background

One of the characteristics of acute lung injury (ALI) is severe pulmonary edema, which is closely related to alveolar fluid clearance (AFC). Mesenchymal stem cells (MSCs) secrete a wide range of cytokines, growth factors, and microRNA (miRNAs) through paracrine action to participate in the mechanism of pulmonary inflammatory response, which increase the clearance of edema fluid and promote the repair process of ALI. The epithelial sodium channel (ENaC) is the rate-limiting step in the sodium–water transport and edema clearance in the alveolar cavity; the role of bone marrow-derived MSC-conditioned medium (BMSC-CM) in edema clearance and how miRNAs affect ENaC are still seldom known.

Methods

CCK-8 cell proliferation assay was used to detect the effect of BMSC-CM on the survival of alveolar type 2 epithelial (AT2) cells. Real-time polymerase chain reaction (RT-PCR) and western blot were used to detect the expression of ENaC in AT2 cells. The effects of miR-34c on lung fluid absorption were observed in LPS-treated mice in vivo, and the transepithelial short-circuit currents in the monolayer of H441 cells were examined by the Ussing chamber setup. Dual luciferase reporter gene assay was used to detect the target gene of miR-34c.

Results

BMSC-CM could increase the viability of mouse AT2 cells. RT-PCR and western blot results showed that BMSC-CM significantly increased the expression of the γ-ENaC subunit in mouse AT2 cells. MiR-34c could restore the AFC and lung wet/dry weight ratio in the ALI animal model, and Ussing chamber assay revealed that miR-34c enhanced the amiloride-sensitive currents associated with ENaC activity in intact H441 cell monolayers. In addition, we observed a higher expression of miR-34c in mouse AT2 cells administrated with BMSC-CM, and the overexpression or inhibition of miR-34c could regulate the expression of ENaC protein and alter the function of ENaC. Finally, we detected that myristoylated alanine-rich C kinase substrate (MARCKS) may be one of the target genes of miR-34c.

Conclusion

Our results indicate that BMSC-CM may alleviate LPS-induced ALI through miR-34c targeting MARCKS and regulate ENaC indirectly, which further explores the benefit of paracrine effects of bone marrow-derived MSCs on edematous ALI.

miR-34c inhibits PDGF-BB-induced HAVSMCs phenotypic transformation and proliferation via PDGFR-β/SIRT1 pathway

The purpose of this study was to explore the effect of miR-34c on PDGF-BB-induced HAVSMCs phenotypic transformation and proliferation via PDGFR-β/SIRT1 pathway, so as to find a new method for early diagnosis and treatment of cardiovascular disease. HA-VSMCs were treated with platelet-derived growth factor-BB (PDGF-BB) at 0 h, 12 h, 24 h, 48 h or 36 h to explore the optimal time for phenotypic transformation of VSMCs. And then, PDGF-BB-induced HA-VSMCs were transfected with miR-34c mimics/mimics NC and pcDNA3.1-PDGFR-β/pcDNA3.1-NC to observe cell biological behaviour. CCK8 was used to detect cell proliferation activity. Transwell chamber assay was used to detect cell invasion. Early apoptosis was analyzed by flow cytometry. The expression of α-SMA and Smemb was detected by immunofluorescence staining. The expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1 were analyzed by Western blot analysis. The expression of miR-34a, miR-34b and miR-34c was detected by RT-PCR, and the targeting relationship between miR-34c and PDGFR-β was detected by luciferase reporting assay. The results indicated the proliferation and migration of PDGF-BB-induced HA-VSMCs significantly increased, and apoptosis significantly decreased. Besides, α-SMA decreased significantly, while Smemb increased significantly. Furthermore, expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1 increased significantly, and SIRT1 decreased significantly. Experimental results showed that, miR-34c mimics significantly inhibited cell proliferation and migration, and promoted cell apoptosis, and miR-34c inhibitor had the opposite effects. MiR-34c mimics significantly increased α-SMA expression and decreased Smemb expression, while the opposite effects were reflected after transfection with miR-34c inhibitor. Moreover, miR-34c mimics significantly decreased the expressions of PDGFR-β, IRF9, Acetyl-NF-κB/p65, Acetyl-p53 and CyclinD1, and significantly increased the expression of SIRT1, while miR-34c inhibitor had the opposite effects. Luciferase assay confirmed that PDGFR-β was a potential target of miR-34c. Subsequently, PDGF-BB-induced HA-VSMCs were co-transfected with miR-34c mimics and pcDNA3.1-PDGFR-β. The results indicated that PDGFR-β reversed the biological function of miR-34c mimic. The results revealed the potential application value of miR-34c as a marker molecule of phenotypic transformation, providing a potential target for improving phenotypic transformation.

miR-34c inhibits proliferation of glioma by targeting PTP1B

Glioma is one of the most pervasive and invasive primary malignancies in the central nervous system. Due to its abnormal proliferation, glioma remains hard to cure at present. Protein tyrosine phosphatase 1B (PTP1B) has been proved to be involved in the process of proliferation in many malignancies. However, whether PTP1B is involved in the proliferation of glioma and how it acts are still unclear. In this study, the PTP1B expressions in glioma tissues and cells were determined by quantitative real-time PCR and western blot analysis. The effects of PTP1B on the proliferation characteristics of glioma were explored using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation assay, and tumor xenografts in mice. We found that the protein and mRNA levels of PTP1B in glioma tissues were significantly higher than those in paired nontumor tissues. MTT and clone formation assays showed that PTP1B is closely related to human glioma cell proliferation. In addition, TargetScan revealed that miR-34c regulates PTP1B. Mechanistically, we proved that miR-34c negatively regulates PTP1B and then participates in the regulation of glioma cell proliferation in vivo. Collectively, these results suggested that miR-34c inhibits the proliferation of human glioma cells by targeting PTP1B, which will provide a potential target for the treatment of glioma.

Mir-34c affects the proliferation and pluripotency of porcine induced pluripotent stem cell (piPSC)-like cells by targeting c-Myc

MicroRNAs are important regulators in stem cells, which involve in gene regulation, including cell proliferation, differentiation and apoptosis. As an important one, miR-34c participates in various processes by targeting protein-coding genes. It is generally considered as a tumor suppressor and cell adhesion inhibitor. However, whether miR-34c has effects on pluripotent stem cells is not clear. Here, by mir-34c mimics transfection, the function of miR-34c on porcine induced pluripotent stem cell (piPSC)-like cells was investigated. Bioinformatics analyses showed that c-Myc is miR-34c's candidate target, which was confirmed by dual Luciferase assay. The knockout of miR-34c indicated that mir-34c affects the proliferation and pluripotency of piPSC-like cells by targeting c-Myc. Our study explored the regulatory mechanism of miR-34c on piPSC-like cells, providing a reference for the establishment of true porcine PSCs.

Corylin suppresses metastasis of breast cancer cells by modulating miR-34c/LINC00963 target

Breast cancer is one of the cancers leading to most death cases among women and metastasis is the major cause of breast cancer mortality. In this study, Corylin, the flavonoid compound which is extracted and purified from Psoralea corylifolia L., the effect on breast cancer metastasis was investigated. Corylin showed inhibitory effect on migration and invasion abilities of breast cancer cells. Meanwhile, the epithelial-mesenchymal transition was also regulated by corylin. The long non-coding RNA LINC00963 was found to have a significantly high expression level in breast cancer while it can be down-regulated by corylin. In addition, both wound-healing assay and transwell assay showed that LINC00963 induced breast cancer cells metastasis. MiR-34c was increased by corylin treatment depending on p53, and it was firstly identified that the LINC00963 was a direct target of miR-34c. Corylin was verified here that it prohibited MCF-7 migration and invasion depending on miR-34c/LINC00963 target. In conclusion, corylin suppresses metastasis of breast cancer cells via increasing miR-34c expression, which was dependent on p53. LINC00963 was a direct target of miR-34c and the target axis was necessary for corylin function. Therefore, corylin is a promising drug candidate and LINC00963 can be seen as a promising target in breast cancer treatment.

MicroRNA-34c-3p target inhibiting NOTCH1 suppresses chemosensitivity and metastasis of non-small cell lung cancer

Background

Chemotherapy is the standard treatment for non-small cell lung cancer (NSCLC). However, chemoresistance frequently occurs, making the treatment of NSCLC more difficult.

Method

We combined clinical and experimental studies to establish the role of microRNA (miR)-34c in NSCLC metastasis and chemoresistance.

Results

MiR-34c expression was significantly decreased in patients with NSCLC who showed a poor chemoresponse and metastasis. Overexpression of miR-34c sensitized NSCLC cells to paclitaxel and cisplatin both in vitro and in vivo. Furthermore, we found that NOTCH1 was target of miR-34c in NSCLC cells and played a key role in the effects of miR-34c on NSCLC.

Conclusion

NSCLC metastasis and chemoresistance are suppressed though the miR-34c/NOTCH1 axis. MiR-34c has important implications in the development of therapeutic strategies for metastasis and chemoresistance in NSCLC.

MiR-34c promotes hepatic stellate cell activation and Liver Fibrogenesis by suppressing ACSL1 expression

Normally, there are multiple microRNAs involved in the pathogenesis of liver fibrosis. In our work, we aimed at identifying the role of miR-34c in the hepatic stellate cell (HSC) activation and liver fibrosis and its potential mechanism. Our results have shown that during natural activation of HSC, the level of miR-34c was increased significantly whereas acyl-CoA synthetase long-chain family member-1(ACSL1), which is a key enzyme can affect fatty acid(FA) synthesis, was decreased. A double fluorescence reporter assay further confirmed that ACSL1 is a direct target gene of miR-34c. Moreover, the inhibition of miR-34C can attenuate the synthesis of collagen in HSC-T6. In our rescue assay, ACSL1 expression was 1.49-fold higher compared to normal control cells which were transfected with the miR-34c inhibitor in a stable low expression ACSL1 cell line. While at the same time, α-SMA and Col1α expression decreased by 18.22% and 2.58%, respectively. Moreover, we performed an in vivo model using dimethylnitrosamine (DMN) in conjunction with the miR-34c agomir, combined with the treatment of DMN and the miR-34c agomir can increase liver fibrosis. Meanwhile, the degree of hepatic fibrosis was increased and lipid droplets reduced dramatically in rats and HSC-T6 cell treated with miR-34c mimics alone compared to untreated groups. Our results indicate that miR-34c plays an essential role in liver fibrosis by targeting ACSL1 closely associated with lipid droplets, and it might be used as a potential therapeutic target.

MiR-34c regulates the proliferation and apoptosis of lung cancer cells

PURPOSE

As miR-34c acts as a tumor suppressant for multiple cancers, the purpose of this study was to investigate that role that miR-34c plays in the proliferation and apoptosis of lung cancer.

METHODS

The expression of miR-34c in 600 patients with lung cancer was quantitatively analyzed with real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) technology and correlated to clinical pathological parameters. The CCK-8 analysis and flow cytometry were carried out to detect cell proliferation and apoptosis in miR-34c-mimic transfected cell lines. Moreover, the regulation of miR-34c to interleukin-6 (IL-6) in cell lines was detected by western blot, qRT-PCR and dual-luciferase reporter assay.

RESULTS

The expression of miR-34c was downregulated in lung cancer compared with adjacent normal tissues. The expression level of miR-34c was linked to stromal invasion. Furthermore, overexpressing miR-34c played an active role in effectively inhibiting cell proliferation and inducing apoptosis. In addition, a significant inverse relationship was exhibited between the expression of miR-34c and IL-6 in tumor tissues.

CONCLUSION

At the molecular level, IL-6 can be used as a direct target of miR-34c in the treatment of lung cancer cells and miR-34c can be used as an effective biomarker and therapeutic target for lung cancer.

LncRNA BANCR induced vascular smooth muscle cell proliferation by downregulating miR-34c methylation in atherosclerosis

Aberrant vascular smooth muscle cell (VSMCs) proliferation involves in the development of atherosclerosis. It reported that Long noncoding BRAF-activated noncoding RNA (BANCR) and miR-34c played opposite roles in the regulation of the proliferation of VSMCs, indicating that there might be a potential interaction between them. This study was to investigate the relationship between BANCR and miR-34c in atherosclerosis. Blood (5 ml) was obtained from 56 patients with atherosclerosis and 56 healthy volunteers after they were fasted overnight, and plasma was extracted from the blood. Human Aortic Smooth Muscle Cells (HASMCs) were used to perform in vitro cell experiments. RT-qPCR was performed to measure the expression of BANCR and miR-34c in plasma and HASMCs. Dual luciferase reporter assay detected the interaction between BANCR and miR-34c. CCK-8 assay was used to assess the effects of BANCR and miR-34c overexpression on the proliferation of HASMCs. Western blotting was used to assess the effects of BANCR and miR-34c overexpression on the protein expression of HMGB1, TNF-ɑ and Bcl-2. In this study, we found that BANCR was upregulated, while miR-34c was downregulated in atherosclerosis. Bioinformatics analysis showed that BANCR and miR-34c could directly interact with each other. Moreover, overexpression of BANCR could decrease the expression of miR-34c in HASMCs, but overexpression of miR-34c could not affect the expression of BANCR. Furthermore, overexpression of BACNR increased miR-34c methylation, and knockdown of endogenous BANCR decreased miR-34c methylation. In addition, overexpression of BANCR reduced the effects of miR-34c on HASMCs proliferation and reversed the effects of miR-34c on HMGB1, TNF-ɑ and Bcl-2 expression. BANCR overexpression could induce HASMCs proliferation by downregulating the miR-34c methylation. Therefore given BANCR upregulation in atherosclerosis, its expression may be considered as a novel and useful biomarker for atherosclerosis prevention and prognosis. However considering the possible effects of other underlying diseases on both BANCR expression and miR-34c in atherosclerosis, further investigation is suggested for future research.

LncRNA TUG1 knockdown mitigates inflammatory injury induced by cigarette smoke extract in chronic obstructive pulmonary disease via miR-34c/BRD4 axis

Chronic obstructive pulmonary disease (COPD) is a type of respiratory disease. The dysregulation of long non-coding RNA (lncRNA) taurine upregulated gene 1 (TUG1) has been reported in diverse diseases. This study aimed to explore the functions and mechanism of TUG1 in COPD. The levels of TUG1 and BRD4 were significantly up-regulated, and the level of miR-34c was apparently down-regulated in COPD patients or CSE-treated BEAS-2B cells. TUG1 was verified to sponge to miR-34c, and BRD4 was validated as a target of miR-34c. TUG1 depletion or miR-34c overexpression promoted cell proliferation but restrained apoptosis, inflammatory response in CSE-treated BEAS-2B cells. MiR-34c inhibitor mitigated the inhibitory effect on cell proliferation and the promotion effects on cell apoptosis, inflammatory response in CSE-treated BEAS-2B cells induced by TUG1 silencing. Mechanistically, TUG1 modulated BRD4 expression in CSE-treated BEAS-2B cells by sponging miR-34c. TUG1 modulated BRD4 to regulate cell proliferation, cell apoptosis and inflammatory response in CSE-treated BEAS-2B cells by sponging miR-34c.

Expression and diagnostic value of miR-34c and miR-141 in serum of patients with colon cancer

Expression of miR-34c and miR-141 in serum of colon cancer patients and their association with clinicopathological features and diagnostic value for colon cancer were investigated. A total of 64 patients with colon cancer admitted to Hubei Cancer Hospital from January 2016 to March 2018 were included in the experimental group, and 64 healthy subjects undergoing physical examination during the same period were the control group. The expression of miR-34c and miR-141 in serum of patients in the two groups were detected by RT-qPCR, and the association of miR-34c and miR-141 with the clinicopathological characteristics of colon cancer patients was analyzed. The receiver operating characteristic (ROC) curve was used to assess the diagnostic efficiency of miR-34c and miR-141 in colon cancer. The expression of miR-141 in serum of patients in the experimental group was significantly higher than that in the control group (P<0.05). Expression of miR-34c in serum of patients in the experimental group was significantly lower than that in the control group (P<0.05) and the expression of miR-34c and miR-141 in serum of the experimental group were associated with tumor diameter, clinical stage, degree of differentiation and lymph node metastasis (P<0.05). AUC of serum miR-34c in the diagnosis of colon cancer was 0.857 (95% CI: 0.795-0.919), with the cut-off value of 0.800, the diagnostic sensitivity of 84.38%, and the specificity of 68.75% and AUC of serum miR-141 in the diagnosis of colon cancer was 0.876 (95% CI: 0.810-0.941), with the cut-off value of 0.282, the diagnostic sensitivity of 70.31%, and the specificity of 96.88%. The ROC curve for the diagnosis of colon cancer was further plotted in combination with serum miR-34c and miR-141. AUC of the two combined for the diagnosis of colon cancer was 0.929 (95% CI: 0.884-0.974), with the cut-off value of 0.566, the diagnostic sensitivity of 84.38%, and the specificity of 93.75%. In conclusion, miR-34c and miR-141 might be involved in the occurrence and progression of colon cancer and could be used as biological indicators for early diagnosis of colon cancer.

Long Non-Coding RNA NEAT1 Regulates Pyroptosis in Diabetic Nephropathy via Mediating the miR-34c/NLRP3 Axis

INTRODUCTION

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus and is considered to be a sterile inflammatory disease. Increasing evidence suggest that pyroptosis and subsequent inflammatory response play a key role in the pathogenesis of DN. However, the underlying cellular and molecular mechanisms responsible for pyroptosis in DN are largely unknown.

METHODS

The rat models of DN were successfully established by single 65 mg/kg streptozotocin treatment. Glomerular mesangial cells were exposed to 30 mmol/L high glucose media for 48 h to mimic the DN environment in vitro. Gene and protein expressions were determined by quantitative real-time PCR and Western blot. Cell viability and pyroptosis were measured by MTT assay and flow cytometry analysis, respectively. The relationship between lncRNA NEAT1, miR-34c, and Nod-like receptor protein-3 (NLRP3) was confirmed by luciferase reporter assay.

RESULTS

We found that upregulation of NEAT1 was associated with the increase of pyroptosis in DN models. miR-34c, as a target gene of NEAT1, mediated the effect of NEAT1 on pyroptosis in DN by regulating the expression of NLRP3 as well as the expressions of caspase-1 and interleukin-1β. Either miR-34c inhibition or NLRP3 overexpression could reverse the accentuation of pyroptosis and inflammation by sh-NEAT1 transfection in the in vitro model of DN.

CONCLUSIONS

Our findings suggested NEAT1 and its target gene miR-34c regulated cell pyroptosis via mediating NLRP3 in DN, providing new insights into understanding the molecular mechanisms of pyroptosis in the pathogenesis of DN.

Down-regulation of LINC00667 hinders renal tubular epithelial cell apoptosis and fibrosis through miR-34c

PURPOSE

This study aimed to down-regulate LINC00667 and inhibit apoptosis and fibrosis of renal tubular epithelial cells through miR-34c.

METHODS

Altogether, 98 patients with chronic kidney disease treated in our hospital were selected as the study group, and 67 normal people were selected as the control group. Epithelial cells of proximal convoluted tubules in human renal cortex were purchased. TGF-β1 was used to induce fibrosis of HK-2 renal tubular epithelial cells. The expression of LINC00667, miR-34c, type I collagen (Col 1) and type III collagen (Col 3) were detected by qRT-PCR and WB.

RESULTS

LINC00667 was highly expressed in cancer tissues and HK-2, while miR-34c was poorly expressed. Inhibition of LINC00667 and over-expression of miR-34c could inhibit the proliferation and invasion of chronic kidney disease cells, but increase the apoptosis rate. Down-regulation of LINC00667 could significantly reduce of Col 1 and Col 3 in renal interstitial fibroblasts induced by TGF-β1, while up-regulation of miR-34c could also achieve this effect. Double luciferase report confirmed that there was a targeted regulatory relationship between LINC00667 and miR-34c.

CONCLUSION

LINC00667 could reduce the proliferation and invasion of chronic kidney disease cells, increase the apoptosis rate by regulating miR-34c, and improve renal fibrosis.

MiR-34c downregulation leads to SOX4 overexpression and cisplatin resistance in nasopharyngeal carcinoma

Background

A major cause of disease-related death in nasopharyngeal carcinoma (NPC) is the development of distant metastasis (DM) despite combination chemoradiotherapy treatment. We previously identified and validated a four microRNA (miRNA) signature that is prognostic for DM. In this study, characterization of a key component of this signature, miR-34c, revealed its role in chemotherapy resistance.

Methods

Two hundred forty-six NPC patient biopsy samples were subject to comprehensive miRNA profiling and immunohistochemistry (IHC). Two human normal nasopharyngeal cell lines (immortalized; NP69 and NP460), as well as the NPC cell line C666–1, were used for miR-34c gain-of-function and loss-of-function experiments. Signaling pathways were assessed using quantitative real-time PCR (qRT-PCR) and Western blot. Cell viability was measured using the ATPlite assay.

Results

MiR-34c was downregulated in NPC patient samples, and confirmed in vitro to directly target SOX4, a master regulator of epithelial-to-mesenchymal transition (EMT). MiR-34c downregulation triggered EMT-representative changes in NP69 and NP460 whereby Snail, ZEB1, CDH2, and SOX2 were upregulated, while Claudin-1 and CDH1 were downregulated. Phenotypically, inhibition of miR-34c led to cisplatin resistance, whereas miR-34c over-expression sensitized NPC cells to cisplatin. TGFβ1 decreased miR-34c and increased SOX4 expression in vitro. The TGFβ receptor 1 inhibitor SB431542 reduced SOX4 expression and increased cisplatin sensitivity. Finally, IHC revealed that lower SOX4 expression was associated with improved overall survival in chemotherapy-treated NPC patients.

Conclusion

miR-34c is downregulated in NPC. Repression of miR-34c was shown to increase SOX4 expression, which leads to cisplatin resistance, while TGFβ1 was found to repress miR-34c expression. Taken together, our study demonstrates that inhibition of the TGFβ1 pathway could be a strategy to restore cisplatin sensitivity in NPC.

The effect of sperm miR-34c on human embryonic development kinetics and clinical outcomes

AIMS

We aimed to investigate the effect of sperm miR-34c on early human embryonic development kinetics and clinical outcomes of in vitro fertilization (IVF) patients.

MATERIALS AND METHODS

After oocyte insemination, residual sperm specimens were collected from 58 patients undergoing IVF. miR-34c expression levels in sperm, oocytes, zygotes, and embryos/blastocysts were detected with qRT-PCR, and embryonic development kinetics were observed using time-lapse technology. To confirm the role of miR-34c in regulation of early embryonic development, miR-34c siRNA was injected into zygotes obtained from in vitro-matured oocytes. A ROC curve was used to determine the cutoff value. Comparisons of embryonic development kinetics and clinical outcomes were performed according to the cutoff value.

KEY FINDINGS

The miR-34c expression level was highest in 3PN zygotes, but was not expressed in human oocytes. In the miR-34c siRNA group, embryonic development kinetic parameters t2, t3, t4, and t5 were significantly prolonged, but the cleavage rate and high-quality embryo rate were lower than in the control group. The levels of sperm miR-34c were negatively correlated with t5 and positively correlated with rates of blastocyst formation, high-quality blastocysts, and pregnancy. The miR-34c levels and the blastocyst formation rate were higher in the pregnancy group (p < 0.05). Logistic regression analysis showed that sperm miR-34c level was significantly correlated with pregnancy (OR: 5.056, 95% CI: 1.560-16.384; p = 0.007).

SIGNIFICANCE

The sperm miR-34c expression level is associated with embryonic development kinetics and clinical outcomes. Thus, miR-34c expression is beneficial to embryonic development and may be used as an indicator of IVF outcomes.

PLOD1, a target of miR-34c, contributes to cell growth and metastasis via repressing LATS1 phosphorylation and inactivating Hippo pathway in osteosarcoma

Although dysregulated PLOD1 was reported in many cancers, its function in osteocarcoma (OS) progression and potential mechanism are totally unknown. In the present study, we found that the mRNA expression of PLOD1 was significantly upregulated in OS cells and tissues. The high expression of PLOD1 was correlated with the aggressive phenotypes of OS and poor prognosis. Gain- or loss-of-function assays demonstrated that PLOD1 promoted proliferation, migration, and invasion of OS cells in vitro, as well as tumorigenicity and metastasis in vivo. We found that PLOD1 inactivated Hippo-YAP pathway through inhibiting phosphorylation-LATS1 (p-LATS1) and -YAP (p-YAP). Immunofluorescence results validated that nuclear distribution of YAP was increased by PLOD1 overexpression and was decreased by PLOD1 depletion. Furthermore, PLOD1 was demonstrated as a target of miR-34c, which inhibited the luciferase activity of PLOD1 mRNA 3'-UTR and PLOD1 expression at both mRNA and protein levels. The expression of miR-34c was downregulated in OS tissues and negatively correlated with PLOD1 mRNA expression. We found that restoration of PLOD1 abolished the miR-34c induced inhibition of cell growth and invasion. More importantly, miR-34c led to upregulation of p-LATS1 and p-YAP, and reducing of nuclear YAP and TAZ in OS cells. The mice tumors, which formed from miR-34c lentivirus vectors, have relatively low expression of PLOD1 and nuclear YAP staining. Taken together, our findings revealed that PLOD1 promoted tumorigenesis and metastasis in OS, and the dysregulated miR-34c/PLOD1/Hippo pathway affected OS progression, providing a potential therapeutic strategy for treatment.

miR-34c Targets MET to Improve the Anti-Tumor Effect of Cisplatin on Ovarian Cancer

Background

Cisplatin is a commonly used drug for the treatment of various types of malignant cancers, including ovarian cancer. However, resistance to cisplatin is still a considerable obstacle to achieve a satisfactory therapeutic effect. The purpose of this study is to develop a strategy to sensitize ovarian cancer cells to cisplatin-induced cytotoxicity.

Methods

miR-34c levels in ovarian cancer tissues and cell lines were tested by qRT-PCR analysis. In vitro assays, the effect of miR-34c on cisplatin was evaluated by using MTT. Expression of MET and phosphorylation of PI3K and AKT were tested by Western blot assays. Conjugation with Bad and Bcl-xl was evaluated through immunoprecipitation. Flow cytometry analysis was performed to measure the apoptotic rate of ovarian cancer cells.

Results

Downregulation of miR-34c was observed in ovarian cancer tissues and cell lines. However, miR-34c overexpression was found to sensitize ovarian cancer cells to cisplatin treatment in vitro and in vivo. Mechanically, we found that miR-34c targeted the MET gene, thereby inhibiting the phosphorylation of PI3K and AKT to activate Bad. As a result, miR-34c reduced resistance of ovarian cancer cells to cisplatin-induced apoptosis.

Conclusion

miR-34c/MET axis promotes cisplatin-induced cytotoxicity against ovarian cancer by targeting the MET/PI3K/AKT/Bad pathway.

Corticotropin-releasing factor suppresses glioma progression by upregulation of long non-coding RNA-p21

Corticotropin-releasing factor (CRF) plays a key role in neuroendocrine regulation of hypothalamo-pituitary-adrenal axis under normal condition and stress by binding to CRF receptor1 (CRFR1). CRF and its receptors have been reported in many types of tumors. Little is known about the role of CRF in the development of glioma. And lincRNA-p21 was reported to act as a role in progression of some cancers. The aim of the present study was to investigate the levels of CRF in glioma, and explore the link between CRF and lincRNA-p21 in this disease. In this study, we found CRF mRNA expression was significantly down-regulated in glioma mice. Moreover, CRF could suppress the proliferation of glioma cells and promote the expression of lincRNA-p21. Afterwards, lincRNA-p21 repressed the proliferation and invasion of glioma cells, which was reversed by miR-34c targeted with 3'-UTR. Furthermore, miR-34c decreased the expression of CRFR1 by binding with the 3'-UTR, which interact with CRF to inhibit the proliferation of glioma cells. Together, these results CRF plays as an important role in glioma progression and metastasis through activation of lincRNA-p21, providing a novel insight for the pathogenesis and underlying therapeutic target for glioma.

MiR-34c Ameliorates Neuropathic Pain by Targeting NLRP3 in a Mouse Model of Chronic Constriction Injury

MicroRNAs have been reported to be an important pathophysiological factor in neuropathic pain. However, the potential mechanism through which miRNAs function in neuropathic pain remains unclear. The purpose of this study was to explore the potential role of mir-34c in neuropathic pain in a mouse model of chronic constriction injury (CCI). We found that overexpression of miR-34c greatly alleviated CCI-induced neuropathic pain and spinal cord infarction, and reduced cell apoptotic and inflammatory cytokine expression in CCI mice. We also demonstrated that miR-34c suppressed the expression of NLRP3 by directly binding the 3'-untranslated region. Overexpression of miR-34c decreased the protein levels of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in the spinal cord in CCI mice. Together, our results indicated that miR-34c may inhibit neuropathic pain development in CCI mice through inhibiting NLRP3-mediated neuroinflammation.

MiR-34c/SOX9 axis regulates the chemoresistance of ovarian cancer cell to cisplatin-based chemotherapy

Cisplatin (DDP)-based chemotherapy is a standard strategy for ovarian cancer (OC), while chemoresistance remains a major therapeutic challenge. Transcription factor SOX9 has been reported to be associated with tumor cell proliferation, metastasis, and chemoresistance. In the current study, we observed a higher SOX9 expression in OC cell lines; SOX9 overexpression might aggravate the chemoresistance of the OC cell to DDP, whereas its knockdown enhanced the chemoresistance. We screened for candidate microRNAs (miRNAs) which might target SOX9 using online tools and further verified the effect of miR-34c, one of the candidate miRNA that significantly inhibited SOX9 expression, in the regulation of OC cell proliferation and chemoresistance to DDP. Further, we verified the interaction between SOX9 and miR-34c, as well as the involvement of β-catenin signaling in this process. Through the analysis of the correlation between miR-34c expression and the clinical features of patients with OC, we revealed that miR-34c might inhibit OC cell proliferation and chemoresistance to improve the prognosis of patients with OC. Further, the expression of SOX9, β-catenin, and c-Myc in OC tissues was upregulated and inversely correlated with miR-34c expression, indicating that rescuing miR-34c expression, thus to inhibit SOX9, β-catenin, and c-Myc expression presents a promising strategy of reducing the chemoresistance of the OC cell to DDP.

miR-34c disrupts spermatogonial stem cell homeostasis in cryptorchid testes by targeting Nanos2

BACKGROUND

Cryptorchidism as a common genitourinary malformation with the serious complication of male infertility draws widespread attention. With several reported miRNAs playing critical roles in spermatogonial stem cells (SSCs), we aimed to explore the fundamental function of the highly conserved miR-34c in cryptorchidism.

METHODS

To explore whether miR-34c participates in spermatogenesis by regulating Nanos2, we examined the effect of overexpression and inhibition for miR-34c on Nanos2 expression in GC-1 cells. Moreover, the expression levels of miR-34c and Nanos2 with cryptorchidism in humans and mice were examined. Furthermore, the homeostasis of SSCs was evaluated through counting the number of promyelocytic leukemia zinc finger (PLZF) positive spermatogonia in murine cryptorchid testes.

RESULTS

In the present study, we show that miR-34c could inhibit the expression of Nanos2 in GC-1 cells. Meanwhile, miR-34c significantly decreased in both the testicular tissues of patients with cryptorchidism and surgery-induced murine model of cryptorchidism. Western blot revealed that the protein level of Nanos2 was up-regulated and showed to be negatively correlated to the expression of miR-34c in our model. The abnormal expression of miR-34c/Nanos2 disrupted the balance between SSC self-renewal and differentiation, eventually damaging the spermatogenesis of cryptorchid testes.

CONCLUSIONS

The miR-34c/Nanos2 pathway provides new insight into the mechanism of male infertility caused by cryptorchidism. Our results indicate that miR-34c may serve as a biological marker for treatment of infertility caused by cryptorchidism.

miRNA-34c Overexpression Causes Dendritic Loss and Memory Decline

Microribonucleic acids (miRNAs) play a pivotal role in numerous aspects of the nervous system and are increasingly recognized as key regulators in neurodegenerative diseases. This study hypothesized that miR-34c, a miRNA expressed in mammalian hippocampi whose expression level can alter the hippocampal dendritic spine density, could induce memory impairment akin to that of patients with Alzheimer’s disease (AD) in mice. In this study, we showed that miR-34c overexpression in hippocampal neurons negatively regulated dendritic length and spine density. Hippocampal neurons transfected with miR-34c had shorter dendrites on average and fewer filopodia and spines than those not transfected with miR-34c (control mice). Because dendrites and synapses are key sites for signal transduction and fundamental structures for memory formation and storage, disrupted dendrites can contribute to AD. Therefore, we supposed that miR-34c, through its effects on dendritic spine density, influences synaptic plasticity and plays a key role in AD pathogenesis.

Knockdown of the oncogene lncRNA NEAT1 restores the availability of miR-34c and improves the sensitivity to cisplatin in osteosarcoma

Aberrant expressions of long non-coding RNAs (lncRNAs) are the culprits of carcinogenesis via regulating the tumor suppressor or oncogene. LncRNA nuclear enriched abundant transcript 1 (NEAT1) has been identified to be an oncogene to promote tumor growth and metastasis of many cancers. However, the clinical significance and function of NEAT1 in osteosarcoma (OS) remain to be discovered. We here collected OS tissues (n=40) and adjacent non-tumor tissues (n=20) to determine the expression of NEAT1 and its clinical significance. NEAT1 was overexpressed in OS tissues, which positively correlated with tumor size, Enneking stage, and distant metastasis of OS patients. The elevated level of NEAT1 was confirmed in OS cell lines including MG63 and HOS in vitro. Knockdown of NEAT1 by two siRNAs induced impaired cell vitalities, promoted the apoptosis, and G₀/G₁ arrest in two cell lines, which was associated with inhibited anti-apoptosis signals BCL-2 pathway and cell cycle-related cyclin D1 (CCND1) signals. Moreover, the tumor suppressor miR-34c was negatively regulated and inhibited by NEAT1 in OS. Suppression of miR-34c could up-regulate the expressions of its target genes BCL-2 and CCND1 to antagonize the effects of NEAT1 knockdown. Furthermore, overexpressed NEAT1 reduced the sensitivity of cisplatin (DDP) and inhibited DDP-induced apoptosis and cell cycle arrest via miR-34c. The results in vivo also confirmed that knockdown of NEAT1 sensitized the OS cells to DPP-induced tumor regression, delayed the tumor growth with reduced levels of Ki-67, BCL-2, and cyclin D1 signals, suggesting that NEAT1 is an oncogene and chemotherapy resistant factor in OS.

Long noncoding RNA DANCR aggravates retinoblastoma through miR-34c and miR-613 by targeting MMP-9

Long non-coding RNAs (lncRNAs) have been identified to play vital roles in cancers, including human retinoblastoma (RB). However, the deepgoing mechanism is still ambiguous. In present study, we investigate the biological role of lncRNA DANCR (differentiation antagonizing non-protein coding RNA) in carcinogenesis of RB. Results revealed that DANCR was up-regulated in RB tissue and cell lines. Moreover, the ectopic overexpression of DANCR indicated poor overall survivals and disease free survival (DFS) for RB patients. In vitro and in vivo experiments, DANCR knockdown suppress the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) correlated protein (N-cadherin, Vimentin) of RB cells. Bioinformatics analysis predicted that miR-34c and miR-613 targeted with 3'-UTR of DANCR, besides, miR-34c and miR-613 also targeted with 3'-UTR of MMP-9, which was validated by luciferase reporter assay. Functional experiments demonstrated that miR-34c and miR-613 could reverse the oncogenic function of DANCR in RB tumorigenesis. In conclusion, our results reveal that DANCR function as competing endogenous RNA (ceRNA) for miR-34c and miR-613 to modulate progression and metastasis in RB oncogenesis via targeting MMP-9, presenting the in-depth regulation of DANCR in RB and providing a novel insight for ceRNA mechanism for RB.

MicroRNA-34c acts as a bidirectional switch in the maturation of insulin-producing cells derived from mesenchymal stem cells

miRNAs regulate insulin secretion, pancreatic development, and beta-cell differentiation. However, their function in the differentiation of IPCs from MSCs is poorly understood. In this study, to screen for miRNAs and their targets that function during the formation of IPCs from MSCs, we examined the miRNA expression profiles of MSCs and IPCs using RNA-seq and qPCR to confirm the above results. We found that miR-34c exhibited transient upregulation at an early stage of the formation of IPCs derived from MSCs. Next, we analyzed the biological function of miR-34c by predicting its targets using bioinformatic tools. Combining our data with those from previous reports, we found that miR-34c and its targets play an important role in the formation of IPCs. Therefore, we overexpressed miR-34c and expressed small interfering RNAs of its targets in MSCs to investigate their functions in IPC formation. We found that miR-34c acts as a bidirectional switch in the formation of IPCs derived from MSCs by regulating the expression of targets to affect insulin synthesis and secretion. miR-34c was shown to downregulate its targets, including PDE7B, PDGFRA, and MAP2K1, to increase proinsulin synthesis, but when miR-34c continually dysregulated such expression, it suppressed the expression of other targets, namely ACSL4 and SAR1A, weakening insulin secretion in IPCs. These results suggest that endogenous miRNAs involved in the formation of IPCs from stem cells should be considered in the development of effective cell transplant therapy for diabetes.

Pien Tze Huang inhibits the proliferation of colorectal cancer cells by increasing the expression of miR-34c-5p

MicroRNAs (miRNAs) are small, short endogenous non-coding RNA that act as oncogenes or tumor suppressors, and serve an important role in various human malignant cancers, including colorectal cancer (CRC). Evidence has indicated that miRNAs regulate the expression of various genes associated with human cancer, in particular the miR-34 family. A well-known traditional Chinese formula, Pien Tze Huang (PZH), has a significant clinical effect on CRC. Previous studies have demonstrated that PZH inhibits CRC growth in vitro and in vivo via multiple mechanisms, including the induction of apoptosis, inhibition of cell proliferation and tumor angiogenesis. To further elucidate the molecular mechanisms underlying the antitumor activity of PZH, in the present study its effects on cell proliferation and miRNA expression in human colon carcinoma (HCT)-8 cell lines was examined. It was observed that treatment with PZH inhibited cell viability and upregulated the expression of miR-34c-5p in HCT-8 cells. In addition, transfection with an miR-34c-5p mimic and treatment with PZH inhibited cell survival and arrested the cell cycle between the G0/G1 and S phase in HCT-8 cells. Furthermore, PZH treatment and transfection with miR-34c-5p downregulated the expression of cyclin-dependent kinase 4 and cMyc (a promoter of cell proliferation), and increased the expression of p53, which is a promoter of apoptosis. These results suggest that PZH may suppress proliferation in CRC cells by upregulating the expression of miR-34c-5p, which provides a novel perspective for understanding the mode of action of PZH.

Persistent distention of colon damages interstitial cells of Cajal through Ca2+ -ERK-AP-1-miR-34c-SCF deregulation

Gastrointestinal motility disorders (GMDs) are attributed to loss of interstitial cells of Cajal (ICC), whose survival and function are deeply dependent on the activation of KIT/SCF signalling. Based on the facts that gastrointestinal distention is common in GMD patients and SCF produced by smooth muscle cells (SMCs) is usually decreased before ICC loss, we considered a possible contribution of persistent gastrointestinal distention/stretch to SCF deficiency. In this study, chronic colonic distention mouse model, diabetic gastrointestinal paresis mouse model, cultured mouse colonic SMCs and colon specimens from Hirschsprung's disease patients were used. The results showed that SCF was clearly decreased in distent colon of mice and patients, and microRNA array and real-time PCR indicated a concomitant increase of miR-34c in distent colon. A negative regulation of miR-34c on SCF expression was confirmed by luciferase reporter assays together with knock-down and overexpression of miR-34c in cultured colonic SMCs. Using EMSA and ChIP assays, we further consolidated that in response to persistent stretch, the transcription factor AP-1/c-Jun was highly activated in colonic SMCs and significantly promoted miR-34c transcription by binding to miR-34c promoter. Knock-down or overexpression of AP-1/c-Jun in cultured colonic SMCs leads to down- or up-regulation of miR-34c, respectively. In addition, the activation of AP-1/c-Jun was through ERK1/2 signalling provoked by Ca²⁺ overload in colonic SMCs that were subject to persistent stretch. In conclusion, our data demonstrated that persistent distention/stretch on colonic SMCs could suppress SCF production probably through Ca²⁺ -ERK-AP-1-miR-34c deregulation, resulting in ICC loss or impairment and GMD progress.

Cortical Morphogenesis during Embryonic Development Is Regulated by miR-34c and miR-204

The porcine brain closely resembles the human brain in aspects such as development and morphology. Temporal miRNA profiling in the developing embryonic porcine cortex revealed a distinct set of miRNAs, including miR-34c and miR-204, which exhibited a highly specific expression profile across the time of cortical folding. These miRNAs were found to target Doublecortin (DCX), known to be involved in neuron migration during cortical folding of gyrencephalic brains. In vivo modulation of miRNA expression in mouse embryos confirmed that miR-34c and miR-204 can control neuronal migration and cortical morphogenesis, presumably by posttranscriptional regulation of DCX.

MiR-34c and PlncRNA1 mediated the function of intestinal epithelial barrier by regulating tight junction proteins in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is originated from uncontrolled inflammation, and desired methods for IBD therapy remains the main difficult. The network comprised with miRNA and lncRNA has been verified to play an important role on diverse human diseases. In this study, we demonstrated the role of miR-34c and lncRNA PlncRNA1 on the function of intestinal barrier.

METHODS

Intestinal epithelial barrier model was constructed based on normal intestinal epithelial cell line Caco-2. 2% DSS was supplemented in the Apical side of the model cells to induce the injury of intestinal epithelial barrier. Real-time PCR or western blot was used to determine mRNA or protein expression of miR-34c, PlncRNA1, Myc-associated zinc finger protein (MAZ), zonula occludens 1 (ZO-1) and occludin.

RESULTS

DSS induced injury of intestinal epithelial barrier, while overexpression of PlncRNA1 seemed to protect intestinal epithelial barrier from injury. Tight junction (TJ) proteins ZO-1 and occludin were regulated by MAZ, while, miR-34c targeted MAZ to regulate its expression, in addition, PlncRNA1 and miR-34c bound together to regulate the expressions of MAZ, ZO-1 and occludin. The protect effects of PlncRNA1 overexpression on intestinal epithelial barrier function was reversed by overexpression of miR-34c.

CONCLUSION

MAZ and TJ proteins were involved in the function of intestinal epithelial barrier, while miR-34c and PlncRNA1 regulated the intestinal dysfunction cooperatively.

miRNA-34c inhibits myoblasts proliferation by targeting YY1

miRNAs are increasingly being implicated as key regulators of cell proliferation, apoptosis, and differentiation. miRNA-34c appears to play a crucial role in cancer pathogenesis wherein it exerts its effect as a tumor suppressor. However, the role of miR-34c in myoblast proliferation remains poorly understood. Here, we found that overexpression miR-34c inhibited myoblasts proliferation by reducing the protein and mRNA expression of cell cycle genes. In contrast, blocking the function of miR-34c promoted myoblasts proliferation and increased the protein and mRNA expression of cell cycle genes. Moreover, miR-34c directly targeted YY1 and inhibited its expression. Similar to overexpression miR-34c, knockdown of YY1 by siRNA suppressed myoblasts proliferation. Our study provides novel evidence for a role of miR-34c in inhibiting myoblasts proliferation by repressing YY1. Thus, miR-34c has the potential to be used to enhance skeletal muscle development and regeneration.

MicroRNA-34c promotes osteoclast differentiation through targeting LGR4

MicroRNAs have emerged as important regulators of osteoclast differentiation in recent years. Of these, miR-34c has been reported to play an important role in bone development. However, its role and the underlying mechanism in osteoclast differentiation remains poorly understood. In this study, we aimed to investigate the precise role and molecular mechanism of miR-34c in osteoclast differentiation. We found an obvious increase in miR-34c expression during osteoclast differentiation in osteoclast precursors induced by receptor activator of nuclear factor κB (NF-κB) ligand and macrophage colony-stimulating factor in vitro. Further experiments showed that overexpression of miR-34c significantly promoted osteoclast differentiation while suppression of miR-34c showed the opposite effect. Interestingly, bioinformatics analysis and dual-luciferase reporter assays showed that miR-34c targets the 3'-untranslated region of leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4). The expression of LGR4 was regulated by miR-34c in osteoclasts. Moreover, miR-34c regulated NF-κB and glycogen synthase kinase 3-β signaling during osteoclast differentiation. Overexpression of LGR4 partially reversed the promoting effect of miR-34c overexpression on osteoclast differentiation. Taken together, our study suggests that miR-34c contributes to osteoclast differentiation by targeting LGR4, providing novel insights into understanding the molecular mechanism underlying osteoclast differentiation.

Lymph node or perineural invasion is associated with low miR-15a, miR-34c and miR-199b levels in head and neck squamous cell carcinoma

Background

MicroRNAs (miRNAs or miRs) are post-transcriptional regulators of eukaryotic cells and knowledge of differences in miR levels may provide new approaches to diagnosis and therapy.

Methods

The present study measured the levels of nine miRs in head and neck squamous cell carcinomas (HNSCC) and determined whether clinical pathological features are associated with differences in miR levels. SET (I2PP2A) and PTEN protein levels were also measured, since their levels can be regulated by miR-199b and miR-21, respectively. Nine miRs (miR-15a, miR-21, miR-29b, miR-34c, miR-100, miR-125b, miR-137, miR-133b and miR-199b) were measured by real time qRT-PCR in HNSCC samples from 32 patients and eight resection margins. SET (I2PP2A) and PTEN protein levels were estimated by immunohistochemistry in paired HNSCC tissues and their matched resection margins.

Results

In HNSCC, the presence of lymph node invasion was associated with low miR-15a, miR-34c and miR-199b levels, whereas the presence of perineural invasion was associated with low miR-199b levels. In addition, miR-21 levels were high whereas miR-100 and miR-125b levels were low in HNSCC compared to the resection margins. When HNSCC line HN12, with or without knockdown of SET, were transfected with miR-34c inhibitor or miR-34c mimic, the miR-34c inhibitor increased cell invasion capacity while miR-34c mimic decreased the cell invasion.

Conclusions

We showed that the levels of specific miRs in tumor tissue can provide insight into the maintenance and progression of HNSCC.

General significance

MiRNAs are up- or down-regulated during cancer development and progression; they can be prognosis markers and therapeutic targets in HNSCC.

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Association between miR-15a, miR-34c and miR-199b levels and lymph node metastasis in HNSCC.

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miR-199b is reduced while SET protein is accumulated in HNSCC.

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Levels of miR-34c control invasion in HNSCC.

MicroRNA-34c Suppresses Breast Cancer Migration and Invasion by Targeting GIT1

Abnormal expression of microRNAs plays important role in tumor metastasis. Migration and invasion of cancer cells accord for the metastasis and deterioration of breast cancer. However, the regulatory role of microRNAs in the invasion and migration of breast cancer cells has not completely understood yet. Here we found that microRNA-34c (miR-34c) was significantly downregulated in metastatic tissue of breast cancer. In vitro study showed that miR-34c negatively regulated GIT1 protein expression by binding to the 3'UTR of GIT1 mRNA. Consistently, GIT1 protein expression was found upregulated significantly in metastatic breast cancer. Moreover, miR-34c overexpression suppressed the expression of GIT1 protein, and this effect was restored by AMO-miR-34c in breast cancer cells. Overexpression of miR-34c suppressed cell migration and invasion in both MCF-7 and MDA-MD-231 breast cancer cells. Furthermore, knockdown of endogenous GIT1 expression reduced the migration and invasion of both two breast cancer cells. Collectively, miR-34c downregulation in breast cancer cells resulted in the upregulation of GIT1, which in turn enhanced the migration and invasion of breast cancer. This study highlights molecular mechanism of migration and invasion of breast cancer cells.

MiR-29c regulates the expression of miR-34c and miR-449a by targeting DNA methyltransferase 3a and 3b in nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is prevalent in South East Asia and Southern China particularly, despite the reported 5-year survival ratio is relative higher than other deadly cancers such as liver, renal, pancreas cancer, the lethality is characterized by high metastatic potential in the early stage and high recurrence rate after radiation treatment. MicroRNA-29c was found to be down-regulated in the serum as well as in the tissue of nasopharyngeal carcinoma tissue.

METHODS

In this study, we found accidentally that the transfection of pre-miR-29c or miR-29c mimics significantly increases the expression level of miR-34c and miR-449a but doesn't affect that of miR-222 using real-time quantitative PCR in nasopharyngeal carcinoma cell lines. To explore the molecular mechanism of the regulatory role, the cells are treated with 5-Aza-2-deoxycytidine (5-Aza-CdR) treatment and the level of miR-34c and miR-449a but not miR-222 accumulated by the treatment. DNA methyltransferase 3a, 3b were down-regulated by the 5-Aza-CdR treatment with western blot and real-time quantitative PCR.

RESULTS

We found that pre-miR-29c or miR-29c mimics significantly increases the expression level of miR-34c and miR-449a. We further found DNA methyltransferase 3a and 3b are the target gene of miR-29c. Restoration of miR-29c in NPC cells down-regulated DNA methyltransferase 3a, 3b, but not DNA methyltransferase T1.

CONCLUSIONS

The regulation of miR-29c/DNMTs/miR-34c\449a is an important molecular axis of NPC development and targeting DNMTs or restoring of miR-29c might be a promising therapy strategy for the prevention of NPC.

Interrupted E2F1-miR-34c-SCF negative feedback loop by hyper-methylation promotes colorectal cancer cell proliferation. Biosci Rep. 2015;36:e00293. [PMID: 26704889 PMCID: PMC4741184 DOI: 10.1042/bsr20150290]

E2F1 promoted miR-34c transcription which reduced its target stem cell factor (SCF) and inhibited colorectal cancer (CRC) cell proliferation. While, SCF increased E2F1 production, suggesting an existence of E2F1-miR-34c-SCF negative feedback loop, which was interrupted by hyper-methylation of miR-34c promoter in CRC cells.

Tumour suppressor miR-34c deficiency resulted from hyper-methylation in its promoter is believed to be one of the main causes of colorectal cancer (CRC). Till date, miR-34c has been validated as a direct target of p53; but previous evidence suggested other transcription factor(s) must be involved in miR-34c transcription. In the present study, we in the first place identified a core promoter region (−1118 to −883 bp) of pre-miR-34c which was embedded within a hyper-methylated CpG island. Secondly, E2F1 promoted miR-34c transcription by physical interaction with the miR-34c promoter at site −897 to −889 bp. The transcriptional activating effect of E2F1 on miR-34c was in a p53 independent manner but profoundly promoted in the presence of p53 with exposure to 5-aza-2′-deoxycytidine (DAC). Thirdly, stem cell factor (SCF), a miR-34c target, was specifically reduced upon an introduction of E2F1 which lead to suppression of CRC cell proliferation. The E2F1-suppressed cell proliferation was partially abrogated by additional miR-34c inhibitor, indicating that the anti-proliferation effect of E2F1 was probably through activating miR-34c-SCF axis. Finally, SCF/KIT signalling increased E2F1 production by reducing its proteosomal degradation dependent on PI3K/Akt-GSK3β pathway. In conclusion, our results suggested the existence of E2F1-miR-34c-SCF negative feedback loop which was interrupted by the hyper-methylation of miR-34c promoter in CRC cells and increased cell proliferation.

Role of miR-34c in ketamine-induced neurotoxicity in neonatal mice hippocampus

Ketamine is a commonly used pediatric anesthetic, but it might affect development, or even induce neurotoxicity in the neonatal brain. We have used an in vivo neonatal mouse model to induce ketamine-related neurotoxicity in the hippocampus, and found that miR-34c, a microRNA associated with pathogenesis of Alzheimer's disease, was significantly upregulated during ketamine-induced hippocampal neurodegeneration. Functional assay of silencing miR-34c demonstrated that downregulation of miR-34c activated PKC-ERK pathway, upregulated anti-apoptotic protein BCL2, and ameliorated ketamine-induced apoptosis in the hippocampus. Cognitive examination with the Morris water maze test showed that ketamine-induced memory impairment was significantly improved by miR-34c downregulation. Thus, miR-34c is important in regulating ketamine-induced neurotoxicity in hippocampus.

Differential Expression of miR-34c and Its Predicted Target Genes in Testicular Tissue at Different Development Stages of Swine

To verified the target genes of miR-34c, bioinformatics software was used to predict the targets of miR-34c. Three possible target genes of miR-34c related to spermatogenesis and male reproductive development: zinc finger protein 148 (ZNF148), kruppel-like factor 4 (KLF4), and platelet-derived growth factor receptor alpha (PDGFRA) were predicted. Then, the expression of miR-34c and its target genes were detected in swine testicular tissue at different developmental stages by quantitative polymerase chain reaction. The results suggested that the expression of PDGFRA has the highest negative correlation with miR-34c. Then immunohistochemical staining was done to observe the morphology of swine testicular tissue at 2-days and 3, 4, 5-months of age, which indicated that PDGFRA was mainly expressed in the support cells near the basement membrane during the early development stages of testicular tissue, but that the expression of PDGFRA was gradually reduced in later stages. Therefore, western blot analyzed that the highest expression of PDGFRA was generated in 2-days old testicular tissues and the expression levels reduced at 3 and 4-months old, which correlated with the results of immunohistochemical staining. In conclusion, PDGFRA is a target gene of miR-34c.

PABPC1 exerts carcinogenesis in gastric carcinoma by targeting miR-34c

As one of the common malignant tumors that threaten human health severely, gastric carcinoma is the second highest cause of cancer death and the fourth most common cancer globally. However, the mechanism underlying gastric cancer is still not fully understood. PABPC1 plays an important role in translation, control the rate of mRNA deadenylation and participates in mRNA decay, which is involved in carcinogenesis. Here in present study, we reported that PABPC1 is an oncogenic protein in gastric carcinoma. The results showed that PABPC1 is upregulated in gastric carcinoma tissues, and high PABPC1 expression predicts poor survival. PABPC1 regulates proliferation and transformation of gastric cancer cells in vitro and in vivo. PABPC1 knockdown induces apoptosis by upregulating pro-apoptotic proteins and downregulating anti-apoptotic proteins. In addition, miR-34c is a target of PABPC1, and miR-34c is critically essential for the function of PABPC1. In summary, PABPC1 exerts carcinogenesis and promotes growth and survival of gastric cancer cells by regulating miR-34c.

The microRNA miR-34c inhibits vascular smooth muscle cell proliferation and neointimal hyperplasia by targeting stem cell factor

The fine balance between proliferation and differentiation of vascular smooth muscle cells (VSMCs) is indispensable for the maintenance of healthy blood vessels, whereas an increase in proliferation participates in pathologic cardiovascular events such as atherosclerosis and restenosis. Here we report that microRNA-34c (miR-34c) targets stem cell factor (SCF) to inhibit VSMC proliferation and neointimal hyperplasia. In an animal model, miR-34c was significantly increased in the rat carotid artery after catheter injury. Transient transfection of miR-34c to either VSMCs or A10 cells inhibited cell survival by inducing apoptosis, which was accompanied by an increase in expression of p21, p27, and Bax. Transfection of miR-34c also attenuated VSMC migration. Bioinformatics showed that SCF is a target candidate of miR-34c. miR-34c down-regulated luciferase activity driven by a vector containing the 3'-untranslated region of SCF in a sequence-specific manner. Forced expression of SCF in A10 cells induced proliferation and migration, whereas knocking-down of SCF reduced cell survival and migration. miR-34c antagomir-induced VSMC proliferation was blocked by SCF siRNA. Delivery of miR-34c to rat carotid artery attenuated the expression of SCF and blocked neointimal hyperplasia. These results suggest that miR-34c is a new modulator of VSMC proliferation and that it inhibits neointima formation by regulating SCF.

KITLG is a novel target of miR-34c that is associated with the inhibition of growth and invasion in colorectal cancer cells

MiR-34c is considered a potent tumour suppressor because of its negative regulation of multiple target mRNAs that are critically associated with tumorigenesis and metastasis. In the present study, we demonstrated a novel target of miR-34c, KITLG, which has been implicated in colorectal cancer (CRC). First, we found a significant negative relationship between miR-34c and KITLG mRNA expression levels in CRC cell lines, including HT-29, HCT-116, SW480 and SW620 CRC cell lines. In silico analysis predicted putative binding sites for miR-34c in the 3' untranslated region (3'UTR) of KITLG mRNA. A dual-luciferase reporter assay further confirmed that KITLG is a direct target of miR-34c. Then, the cell lines were infected with lentiviruses expressing miR-34c or a miR-34c specific inhibitor. Restoration of miR-34c dramatically reduced the expression of KITLG mRNA and protein, while silencing of endogenous miR-34c increased the expression of KITLG protein. The miR-34c-mediated down-regulation of KITLG was associated with the suppression on proliferation, cellular transformation, migration and invasion of CRC cells, as well as the promotion on apoptosis. Knockdown of KITLG by its specific siRNA confirmed a critical role of KITLG down-regulation for the tumour-suppressive effects of miR-34c in CRC cells. In conclusion, our results demonstrated that miR-34c might interfere with KITLG-related CRC and could be a novel molecular target for CRC patients.

Increased microRNA-34c abundance in Alzheimer's disease circulating blood plasma

Circulating microRNAs, present either in the cellular component, peripheral blood mononuclear cells (PBMC), or in cell-free plasma, have emerged as biomarkers for age-dependent systemic, disease-associated changes in many organs. Previously, we have shown that microRNA (miR)-34a is increased in circulating PBMC of Alzheimer's disease (AD) patients. In the present study, we show that this microRNA's sister, miR-34c, exhibits even greater increase in both cellular and plasma components of AD circulating blood samples, compared to normal age-matched controls. Statistical analysis shows the accuracy of levels of miR-34c assayed by receiver operating characteristic (ROC) analysis: the area under the curve is 0.99 (p < 0.0001) and the 95% confidence level extends from 0.97 to 1. Pearson correlation between miR-34c levels and mild and moderate AD, as defined by the mini-mental state examination (MMSE), shows an r-value of −0.7, suggesting a relatively strong inverse relationship between the two parameters. These data show that plasma levels of microRNA 34c are much more prominent in AD than those of its sister, miR-34a, or than its own level in PBMC. Transfection studies show that miR-34c, as does its sister miR-34a, represses the expression of several selected genes involved in cell survival and oxidative defense pathways, such as Bcl2, SIRT1, and others, in cultured cells. Taken together, our results indicate that increased levels of miR-34c in both PBMC and plasma may reflect changes in circulating blood samples in AD patients, compared to age-matched normal controls.