RAB5A in triple-negative breast cancer: a critical role in macrophage reshaping in an exosomal miR-21-dependent manner

Breast cancer is the leading cause of cancer-related deaths in females, and triple-negative breast cancer (TNBC) is characterized as one of the main subtypes of breast cancer, with poor prognosis and limited treatments. Investigating the molecular basis or discovering relevant oncogenes will greatly help in developing effective targeted therapies. In this study, we ascertained that RAB5A depletion in TNBC cells suppresses the secretion of exosomes and blocks the polarization of macrophages toward an M2 phenotype. By scanning miRNAs associated with macrophage polarization, we identified that miR-21 was the pivotal component in tumor cell-derived exosomes and played a key role in RAB5A-mediated macrophage polarization. The enhanced expression of miR-21 in macrophages is able to potentiate the M2 polarization of macrophages in the presence of tumor cells. Pellino-1 (PELI1) was subsequently identified as the target of miR-21, and forced PELI1 expression partially abrogated the M2 polarization of macrophages induced by miR-21 overexpression. Macrophages stimulated with RAB5A-depleted TNBC cells (coculture, conditioned medium or exosomes) impaired their capability to promote the proliferation, migration, and invasion of tumor cells. In vivo xenograft experiments further confirmed that RAB5A knockdown TNBC cells exhibited reduced tumor formation and impaired tumor-associated macrophage recruitment. These studies shed light on the potential underlying mechanism of RAB5A-mediated macrophage polarization in an exosomal miR-21-dependent manner and provide an experimental basis for the development of RAB5A- or exosome-based tumor therapeutic strategies.

Exploring research progress in studying serum exosomal miRNA-21 as a molecular diagnostic marker for breast cancer

Breast cancer is one of the most prevalent malignancies affecting women globally and poses a significant public health challenge. Early clinical detection plays a pivotal role in providing optimal treatment opportunities and favorable prognoses, crucial for reducing breast cancer mortality and enhancing patients' quality of life. Therefore, the timely identification and diagnosis of breast cancer are imperative. Conventional tumor markers, such as carcinoembryonic antigen (CEA) and carbohydrate antigen 15-3 (CA15-3), serve as reliable methods for actively monitoring disease progression and have become a routine auxiliary diagnostic approach in clinical settings. However, these biomarkers exhibit limitations in sensitivity and specificity, particularly in the early screening and diagnosis of tumors, often yielding results inconsistent with clinical manifestations. In recent years, research has increasingly focused on exosomes released by tumor cells as potential new biomarkers for early stage breast cancer screening. Exosomes carry various components, including tumor-derived proteins, nucleic acids, and lipids. This paper delves into the specific utilization of serum exosomal microRNA-21 (miR-21) as a biomarker for early detection and diagnosis of breast cancer, evaluating its efficacy within this framework.

miR-21-5p Modulates Airway Inflammation and Epithelial-Mesenchymal Transition Processes in a Mouse Model of Combined Allergic Rhinitis and Asthma Syndrome

INTRODUCTION

Combined allergic rhinitis and asthma syndrome (CARAS) is a concurrent allergic symptom of diseases of allergic rhinitis and asthma. However, the mechanism of CARAS remains unclear. The study aimed to investigate the impact of microRNA-21 (miR-21) on CARAS via targeting poly (ADP-ribose) polymerase-1 (PARP-1) and phosphoinositide 3-kinase (PI3K)/AKT pathways.

METHODS

The levels of miR-21-5p and PARP-1 in CARAS patients were detected by quantitative reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). An ovalbumin-sensitized mouse model of CARAS was established. And knock down of miR-21-5p was constructed by intranasally administering with miR-21-5p shRNA-encoding adeno-associated virus vector. Airway resistance and airway inflammatory response were detected. ELISA was used to evaluate IL-4/IL-5/IL-13 levels in bronchoalveolar lavage fluid (BALF). Expression levels of E-cadherin, fibronectin, and α-SMA were determined using Western blotting. The levels of PARP-1 and the activation of PI3K/AKT were assayed.

RESULTS

Downregulation of miR-21-5p relieved pathophysiological symptoms of asthma including airway hyperreactivity and inflammatory cell infiltration. Downregulation of miR-21-5p significantly reduced the levels of IL4, IL-5, and IL-13 in BALF. Additionally, downregulation of miR-21-5p inhibited the epithelial-mesenchymal transition (EMT) process in CARAS mice. Furthermore, miR-21-5p regulated PARP-1 and was involved in PI3K/AKT activation in CARAS mice.

CONCLUSION

Downregulation of miR-21-5p ameliorated CARAS-associated lung injury by alleviating airway inflammation, inhibiting the EMT process, and regulating PARP-1/PI3K/AKT in a mouse model of CARAS.

MiR-21 Regulates Growth and Migration of Cervical Cancer Cells by RECK Signaling Pathway

Expression of miR-21 has been found to be altered in almost all types of cancers, and it has been classified as an oncogenic microRNA. In addition, the expression of tumor suppressor gene RECK is associated with miR-21 overexpression in high-grade cervical lesions. In the present study, we analyze the role of miR-21 in RECK gene regulation in cervical cancer cells. To identify the downstream cellular target genes of upstream miR-21, we silenced endogenous miR-21 expression using siRNAs. We analyzed the expression of miR-21 and RECK, as well as functional effects on cell proliferation and migration. We found that in cervical cancer cells, there was an inverse correlation between miR-21 expression and RECK mRNA and protein expression. SiRNAs to miR-21 increased luciferase reporter activity in construct plasmids containing the RECK-3'-UTR microRNA response elements MRE21-1, MRE21-2, and MRE21-3. The role of miR-21 in cell proliferation was also analyzed, and cancer cells transfected with siRNAs exhibited a markedly reduced cell proliferation and migration. Our findings indicate that miR-21 post-transcriptionally down-regulates the expression of RECK to promote cell proliferation and cell migration inhibition in cervical cancer cell survival. Therefore, miR-21 and RECK may be potential therapeutic targets in gene therapy for cervical cancer.

Decrease of exosomal miR-21-5p and the increase of CD62p+ exosomes are associated with the development of sepsis in polytraumatized patients

Sepsis as a severe systemic inflammation leads oftentimes to organ dysfunction and subsequently to death. In polytrauma patients, septic complications represent with 45% the predominant cause of late death and are responsible for extremely high costs in the healthcare system. Therefore, clinicians have to detect as early as possible the begin of sepsis to improve the patient's outcome. One new promising diagnostic tool to diagnose septic complications in polytraumatized patients are exosomes. Plasma samples from polytraumatized patients (Injury Severity Score (ISS) ≥16) which developed sepsis (n = 10) and without sepsis (n = 10), were collected at emergency room (ER), 24h and 5 days after trauma. The EVs subpopulations were investigated by a bead-based multiplex flow cytometry measurement of surface epitopes and were compared with plasma EVs from healthy controls (n = 10). Moreover, exosomal cytokine concentrations were measured via high-sensitive ELISA and were correlated with systemic concentrations. For miRNA cargo analysis, we analysed the miRNAs miR-1298-5p, miR-1262, miR-125b-5p, miR-92a-3p, miR-93-5p, miR-155-5p and miR-21-5p and compared their exosomal concentrations by means of RT-qPCR. CD62p + exosomes were significantly increased in septic polytrauma-patients (p ≤ 0.05), while CD40+exosomes, as well as CD49e + exosomes were diminished (p ≤ 0.05). Furthermore, we observed that the exosomal IL-6 concentration reflects the systemic IL-6 concentration (r2 = 0.63) and did not significantly alter between patients with and without sepsis. The exosomal IL-10 concentration seemed to be constant in all patients and healthy controls. We observed that a decrease of miR-21-5p in exosomes was associated with the development of sepsis (p ≤ 0.05), while exosomal miR-93-5p, miR-155-5p and miR-92a-3p were not specifically altered in septic patients. Taken together, the present study in polytraumatized patients demonstrated that the development of sepsis is associated with an increase of CD62p + exosomes. Furthermore, the exosomal cargo was changed in septic patients: miR-21-5p was diminished.

Genomic and epigenetic characterization of the arsenic-induced oncogenic microRNA-21

As one of the first identified oncogenic microRNAs, the precise details concerning the transcriptional regulation and function of microRNA-21 (miR-21) are still not completely established. The miR-21 gene is situated on chromosome 17q23.2, positioned at the 3'-UTR of the gene that encodes vacuole membrane protein-1 (VMP1). In this current study, we presented evidence indicating that miR-21 possesses its own gene promoter, which can be found in the intron 10 of the VMP1 gene. Chromatin immunoprecipitation followed by global DNA sequencing (ChIP-seq) revealed the presence of a broad H3K4me3 peak spanning the entire gene body of the primary miR-21 and the existence of super-enhancer clusters in the close proximity to both the miR-21 gene promoter and the transcription termination site in arsenic (As3+)-induced cancer stem-like cells (CSCs) and human induced pluripotent stem cells (hiPSCs). In non-transformed human bronchial epithelial cells (BEAS-2B), As3+ treatment enhanced Nrf2 binding to both the host gene VMP1 of miR-21 and the miR-21 gene. Knockout of Nrf2 inhibited both the basal and As3+-induced expressions of miR-21. Furthermore, the As3+-enhanced Nrf2 peaks in ChIP-seq fully overlap with these super-enhancers enriched with H3K4me1 and H3K27ac in the miR-21 gene, suggesting that Nrf2 may coordinate with other transcription factors through the super-enhancers to regulate the expression of miR-21 in cellular response to As3+. These findings demonstrate the unique genetic and epigenetic characteristics of miR-21 and may provide insights into understanding the novel mechanisms linking environmental As3+ exposure and human cancers.

Hypoxic-preconditioned mesenchymal stem cell-derived small extracellular vesicles promote the recovery of spinal cord injury by affecting the phenotype of astrocytes through the miR-21/JAK2/STAT3 pathway

BACKGROUND

Secondary injury after spinal cord injury (SCI) is a major obstacle to their neurological recovery. Among them, changes in astrocyte phenotype regulate secondary injury dominated by neuroinflammation. Hypoxia-preconditioned mesenchymal stem cells (MSCs)-derived extracellular vesicle (H-EV) plays a multifaceted role in secondary injury by interacting with cellular components and signaling pathways. They possess anti-inflammatory properties, regulate oxidative stress, and modulate apoptotic pathways, promoting cell survival and reducing neuronal loss. Given the unique aspects of secondary injury, H-EV shows promise as a therapeutic approach to mitigate its devastating consequences. Our study aimed to determine whether H-EV could promote SCI repair by altering the phenotype of astrocytes.

METHODS

Rat bone marrow MSCs (BMSCs) and EVs secreted by them were extracted and characterized. After the SCI model was successfully constructed, EV and H-EV were administered into the tail vein of the rats, respectively, and then their motor function was evaluated by the Basso-Beattie-Bresnahan (BBB) score, Catwalk footprint analysis, and electrophysiological monitoring. The lesion size of the spinal cord was evaluated by hematoxylin-eosin (HE) staining. The key point was to use glial fibrillary acidic protein (GFAP) as a marker of reactive astrocytes to co-localize with A1-type marker complement C3 and A2-type marker S100A10, respectively, to observe phenotypic changes in astrocytes within tissues. The western blot (WB) of the spinal cord was also used to verify the results. We also compared the efficacy differences in apoptosis and inflammatory responses using terminal deoxynucleotidyl transferase dUTP terminal labeling (TUNEL) assay, WB, and enzyme-linked immunosorbent assay (ELISA). Experiments in vitro were also performed to verify the results. Subsequently, we performed microRNA (miRNA) sequencing analysis of EV and H-EV and carried out a series of knockdown and overexpression experiments to further validate the mechanism by which miRNA in H-EV plays a role in promoting astrocyte phenotypic changes, as well as the regulated signaling pathways, using WB both in vivo and in vitro.

RESULTS

Our findings suggest that H-EV is more effective than EV in the recovery of motor function, anti-apoptosis, and anti-inflammatory effects after SCI, both in vivo and in vitro. More importantly, H-EV promoted the conversion of A1 astrocytes into A2 astrocytes more than EV. Moreover, miR-21, which was found to be highly expressed in H-EV by miRNA sequencing results, was also demonstrated to influence changes in astrocyte phenotype through a series of knockdown and overexpression experiments. At the same time, we also found that H-EV might affect astrocyte phenotypic alterations by delivering miR-21 targeting the JAK2/STAT3 signaling pathway.

CONCLUSION

H-EV exerts neuroprotective effects by delivering miR-21 to promote astrocyte transformation from the A1 phenotype to the A2 phenotype, providing new targets and ideas for the treatment of SCI.

Cancer-associated fibroblasts promote stemness maintenance and gemcitabine resistance via HIF-1α/miR-21 axis under hypoxic conditions in pancreatic cancer

Gemcitabine (GEM) resistance affects chemotherapy efficacy of pancreatic cancer (PC). Cancer-associated fibroblasts (CAFs) possess the ability of regulating chemoresistance. This study probed the mechanism of hypoxia-treated CAFs regulating cell stemness and GEM resistance in PC. Miapaca-2/SW1990 were co-cultured with PC-derived CAFs under normoxic/hypoxic conditions. Cell viability/self-renewal ability was determined by MTT/sphere formation assays, respectively. Protein levels of CD44, CD133, Oct4, and Sox2 were determined by western blot. GEM tumoricidal assay was performed. PC cell GEM resistance was evaluated by MTT assay. CAFs were cultured at normoxia/hypoxia. HIF-1α and miR-21 expression levels were assessed by RT-qPCR and western blot, with their binding sites and binding relationship predicted and verified. CAF-extracellular vesicles (EVs) were incubated with Miapaca-2 cells. The RAS/AKT/ERK pathway activation was detected by western blot. PC xenograft models were established and treated with hypoxic CAF-EVs and GEM. CAFs and PC cell co-culture increased cell stemness maintenance, GEM resistance, cell viability, stem cell sphere number, and protein levels of CD44, CD133, Oct4, and Sox2, and weakened GEM tumoricidal ability to PC cells, with the effects further enhanced by hypoxia. Hypoxia induced HIF-1α and miR-21 overexpression in CAFs. Hypoxia promoted CAFs to secrete high-level miR-21 EVs via the HIF-1α/miR-21 axis, and activated the miR-21/RAS/AKT/ERK pathway. CAF-EVs promoted GEM resistance in PC via the miR-21/RAS/ATK/ERK pathway in vivo. Hypoxia promoted CAFs to secrete high-level miR-21 EVs through the HIF-1α/miR-21 axis, and activated the miR-21/RAS/AKT/ERK pathway via EVs to trigger stemness maintenance and GEM resistance in PC.

Evaluation of New Cardiac Damage Biomarkers in Polytrauma: GDF-15, HFABP and uPAR for Predicting Patient Outcomes

Background: Polytrauma is one of the leading mortality factors in younger patients, and in particular, the presence of cardiac damage correlates with a poor prognosis. Currently, troponin T is the gold standard, although troponin is limited as a biomarker. Therefore, there is a need for new biomarkers of cardiac damage early after trauma. Methods: Polytraumatized patients (ISS ≥ 16) were divided into two groups: those with cardiac damage (troponin T > 50 pg/mL, n = 37) and those without cardiac damage (troponin T < 12 pg/mL, n = 32) on admission to the hospital. Patients' plasma was collected in the emergency room 24 h after trauma, and plasma from healthy volunteers (n = 10) was sampled. The plasma was analyzed for the expression of HFABP, GDF-15 and uPAR proteins, as well as miR-21, miR-29, miR-34, miR-122, miR-125b, miR-133, miR-194, miR-204, and miR-155. Results were correlated with patients' outcomes. Results: HFABP, uPAR, and GDF-15 were increased in polytraumatized patients with cardiac damage (p < 0.001) with a need for catecholamines. HFABP was increased in non-survivors. Analysis of systemic miRNA concentrations showed a significant increase in miR-133 (p < 0.01) and miR-21 (p < 0.05) in patients with cardiac damage. Conclusion: All tested plasma proteins, miR-133, and miR-21 were found to reflect the cardiac damage in polytrauma patients. GDF-15 and HFABP were shown to strongly correlate with patients' outcomes.

miRNAs as Biomolecular Markers for Food Safety, Quality, and Traceability in Poultry Meat-A Preliminary Study

In this study, the expression and abundance of two candidate chicken (Gallus gallus; gga) microRNAs (miRNAs, miR), gga-miR-21-5p (miR-21) and gga-miR-126-5p (miR-126), have been analyzed in order to identify biomarkers for the traceability and quality of poultry meat. Two breeds of broiler chickens were tested: the most common Ross308 (fast-growing) and the high-quality Ranger Gold (slow-growing). A preliminary analysis of the two miRNAs expressions was conducted across various tissues (liver, lung, spleen, skeletal muscle, and kidney), and the three tissues (lung, spleen, and muscle) with a higher expression were chosen for further analysis. Using quantitative reverse transcription polymerase chain reaction (RT-qPCR), the expression of miRNAs in the three tissues of a total of thirteen animals was determined. The results indicate that miR-126 could be a promising biomarker for the lung tissue in the Ranger Gold (RG) breed (p < 0.01), thus suggesting a potential applicability for tracing hybrids. RG exhibits a significantly higher miR-126 expression in the lung tissue compared to the Ross308 broilers (R308), an indication of greater respiratory capacity and, consequently, a higher oxidative metabolism of the fast-growing hybrid. During sampling, two R308 broilers presented some anomalies, including airsacculitis, hepatic steatosis, and enlarged spleen. The expression of miR-126 and miR-21 was compared in healthy animals and in those presenting anomalies. Chickens with airsacculitis and hepatic steatosis showed an up-regulation of miR-21 and miR-126 in the most commercially valuable tissue, the skeletal muscle or breast (p < 0.05).

Circulating miR-206, miR-181b, and miR-21 as promising biomarkers in hypothyroidism and their relationship to related hyperlipidemia and hepatic steatosis

Background: Thyroid hormones (THs) signaling has profound effects on many physiological processes. The regulation of THs signaling in various tissues involves the action of microRNAs (miRNAs) on thyroid deiodinases and receptors. THs regulate the expression of certain miRNAs and their target messenger RNAs (mRNAs) in various tissues and cells. The modulation of miRNA levels by THs affects their functions in processes such as liver lipid metabolism, skin physiology, and muscle and heart performance. Aim: This research aimed to investigate miR-181b, miR-206, and miR-21 in the serum of patients with subclinical and overt hypothyroidism to determine their possible role in the diagnosis of the disease and their relationship to clinical disorders related to hypothyroidism. Methods: This study included ninety participants, divided evenly into three groups as follows: patients with overt hypothyroidism diagnosed clinically, radiologically, and by investigation, subclinical hypothyroid patients, and healthy volunteers. The patients had a thorough medical history and underwent a clinical examination. Laboratory tests included plasma cholesterol, LDL, HDL, TGs, liver and renal function tests, CBC, fasting insulin, HOMA-IR, HbA1c, TSH, and free T4. The serum levels of miR-21, miR-206, and miR-181b were measured using qRT-PCR. Results: miR-206 and miR-181b levels were higher in the subclinical group, followed by the hypothyroid and control groups. For miR-21, there was a significantly lower mean value in both the hypothyroid and subclinical groups than in the control group, with no difference between the two groups. Both miR-206 and miR-181b showed a significant negative association with albumin and free T4 levels and a significant direct association with GGT, ALT, AST, creatinine, uric acid, TGs, TC, LDL, TSH, thyroid volume, and CAP score. The same correlation pattern was observed for miR-181b, except that it was not significantly correlated with the TGs. For miR-21 levels, there was a significant positive correlation with albumin, free T4 level, and kPa score and a negative correlation with GGT, ALT, AST, creatinine, uric acid, HOMA-IR, HbA1c, TC, LDL, TSH, and CAP score. Cases with F1 kPa score and S2 CAP scores had significantly higher averages for miR-206 and miR-181b, with a p-value of 0.05. Moreover, miR-21 levels were significantly lower in the S2 CAP score group. Conclusion: These miRNAs (miR-206, miR-181b, and miR-21) may be used as diagnostic biomarkers for hypothyroidism. They may be used as therapeutic targets to control dyslipidemia and hepatic steatosis during hypothyroid disease.

Electroacupuncture Promotes Nerve Regeneration and Functional Recovery Through Regulating lncRNA GAS5 Targeting miR-21 After Sciatic Nerve Injury

Although the benefits of electroacupuncture (EA) for peripheral nerve injury (PNI) are well accepted in clinical practice, the underlying mechanism remains incompletely elucidated. In our study, we observed that EA intervention led to a reduction in the expression of the long non-coding RNA growth-arrest-specific transcript 5 (GAS5) and an increased in miR-21 levels within the injured nerve, effectively promoting functional recovery and nerve regeneration following sciatic nerve injury (SNI). In contrast, administration of adeno-associated virus expressing GAS5 (AAV-GAS5) weakened the therapeutic effect of EA. On the other hand, both silencing GAS5 and introducing a miR-21 mimic prominently enhanced the proliferation activity and migration ability of Schwann cells (SCs), while also inhibiting SCs apoptosis. On the contrary, inhibition of SCs apoptosis was found to be mediated by miR-21. Additionally, overexpression of GAS5 counteracted the effects of the miR-21 mimic on SCs. Moreover, SCs that transfected with the miR-21 mimic promoted neurite growth in hypoxia/reoxygenation-induced neurons, which might be prevented by overexpressing GAS5. Furthermore, GAS5 was found to be widely distributed in the cytoplasm and was negatively regulated by miR-21. Consequently, the targeting of GAS5 by miR-21 represents a potential mechanism through which EA enhances reinnervation and functional restoration following SNI. Mechanistically, the GAS5/miR-21 axis can modulate the proliferation, migration, and apoptosis of SCs while potentially influencing the neurite growth of neurons.

[Retracted] Role of the AKT pathway in microRNA expression of human U251 glioblastoma cells

Following the publication of the above article, a concerned reader drew to the Editor's attention that, regarding the western blots featured in Fig. 3B on p. 670, the bands featured in the U251 and U251‑MC lanes for the miR‑21 and U6 experiments appeared to be duplicates of each other. Moreover, certain of these data were strikingly similar to data that appeared in another article published at around the same time featuring some of the same authors (again, with apparent duplications of bands within the same gel slices, as they were presented). After having conducted an internal investigation of this matter, the Editor of International Journal of Oncology has judged that the apparently anomalous grouping of the data could not have been attributed to pure coincidence. Therefore, the Editor has decided that this article should be retracted from the publication on the grounds of an overall lack of confidence in the data. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor sincerely apologizes to the readership for any incovenience caused, and we thank the reader for bringing this matter to our attention. [International Journal of Oncology 36: 665‑672, 2010; DOI: 10.3892/ijo_00000542].

Expression of Circulating miR-21 and -29 and their Association with Myocardial Fibrosis in Hypertrophic Cardiomyopathy

BACKGROUND

Hypertrophic Cardiomyopathy (HCM) is characterized by myocardial hypertrophy, fibrosis, and sarcomeric disarray.

OBJECTIVE

To evaluate the expression levels of circulating miR-21 and -29 in patients with HCM and their association with clinical characteristics and myocardial fibrosis.

METHODS

In this case-control study, 27 subjects with HCM, 13 subjects with hypertensive cardiomyopathy, and 10 control subjects were enrolled. Evaluation of patients' functional capacity was made by the six-minute walk test. Echocardiographic measurements of left ventricle systolic and diastolic function were conducted. Cardiac magnetic resonance late gadolinium enhancement (LGE) -through a semiquantitative evaluation- was used in the assessment of myocardial fibrosis extent in HCM patients. The expression of miR-21 and -29 in peripheral blood samples of all patients was measured via the method of quantitative reverse transcription polymerase chain reaction.

RESULTS

Circulating levels of miR-21 were higher in both hypertensive and HCM (p<0.001) compared to controls, while expression of miR-29 did not differ between the three studied groups. In patients with HCM and LGE-detected myocardial fibrosis in more than 4 out of 17 myocardial segments, delta CT miR-21 values were lower than in patients with myocardial LGE in 3 or fewer myocardial segments (2.71 ± 1.06 deltaCT vs. 3.50 ± 0.55 deltaCT, p=0.04), indicating the higher expression of circulating miR-21 in patients with more extensive myocardial fibrosis.

CONCLUSION

MiR-21 was overexpressed in patients with HCM and hypertensive cardiomyopathy. Importantly, in patients with HCM, more extensive myocardial fibrosis was associated with higher levels of miR-21.

Apigenin accelerates wound healing in diabetic mice by promoting macrophage M2-type polarization via increasing miR-21 expression

The alteration of inflammatory phenotype by macrophage polarization plays an important role in diabetic wound repair. Apigenin has been reported to be anti-inflammatory and promote tissue repair; however, whether it regulates macrophage polarization to participate in diabetic wound repair remains to be investigated. We found that apigenin promoted miR-21 expression in LPS-stimulated RAW264.7 cells, inhibited cellular M1-type factor TNF-α and IL-1β secretion and increased M2-type factor IL-10 and TGF-β secretion, and accelerated macrophage conversion from M1 type to M2 type, whereas this protective effect of apigenin was counteracted by a miR-21 inhibitor. Moreover, we established a macrophage-HUVECs cell in vitro co-culture system and found that apigenin accelerated the migration, proliferation, and VEGF secretion of HUVECs by promoting macrophage miR-21 expression. Further, mechanistic studies revealed that this was mediated by the TLR4/Myd88/NF-κB axis. In in vivo study, diabetic mice had significantly delayed wound healing compared to non-diabetic mice, accelerated wound healing in apigenin-treated diabetic mice, and decreased M1-type macrophages and increased M2-type macrophages in wound tissues.

Oral cancer cell to endothelial cell communication via exosomal miR-21/RMND5A pathway

Required for meiotic nuclear division 5 homolog A (RMND5A), a novel ubiquitin E3 Ligase, has been reported to correlate with poor prognosis of several cancers. However, its role in endothelial cells has not been reported. In this study, overexpression of RMND5A in human umbilical vein endothelial cells (HUVECs) was performed via lentiviral infection, followed by MTT, would healing and tube formation assay as well as signaling analysis. Moreover, crosstalk between HUVECs and oral squamous cell carcinoma (OSCC) cells was investigated by indirect co-culture with condition medium or tumor cell derived exosomes. Our results showed that overexpression of RMND5A reduced the proliferation, migration and tube formation ability of HUVECs by inhibiting the activation of ERK and NF-κB pathway. Interestingly, OSCC cells can inhibit RMND5A expression of endothelial cells via exosomal miR-21. In summary, our present study unveils that OSCC cells can activate endothelial cells via exosomal miR-21/RMND5A pathway to promote angiogenesis, which may provide novel therapeutic targets for the treatment of OSCC.

Liquid biopsy evaluation of circulating tumor DNA, miRNAs, and cytokines in meningioma patients

Introduction

Liquid biopsy is a non-invasive method used to detect cancer and monitor treatment responses by analyzing blood or other bodily fluids for cancer biomarkers. Meningiomas are the most common primary central nervous system tumors, and biomarkers play a crucial role in their diagnosis, prognosis, and treatment monitoring. The World Health Organization (WHO) classifies meningiomas based on tumor grades and molecular alterations in genes such as in NF2, AKT1, TRAF7, SMO, PIK3CA, KLF4, SMARCE1, BAP1, H3K27me3, TERT promoter, and CDKN2A/B. Liquid biopsy, specifically cell-free DNA (cfDNA) analysis, has shown potential for monitoring meningiomas as it can detect ctDNA release in the blood, unaffected by the blood-brain barrier. MicroRNAs (miRNAs) have also been found to be deregulated in various cancers, including meningiomas, presenting potential as diagnostic biomarkers. Additionally, studying cytokines in the tumor microenvironment may aid in establishing prognostic or diagnostic panels for meningiomas.

Methods

In the present study we analyzed the DNA coming from both the plasma and tumor samples, in addition to analyze miRNA-21 and cytokines in the plasma of 28 meningioma patients.

Discussion and Conclusion

Our findings indicate that the detection of ctDNA in the plasma of meningioma patients is feasible. However, it's important to note that certain challenges persist when comparing plasma DNA analysis to that of tumor tissues. In our study, we observed a paired identification of mutations in only one patient, highlighting the complexities involved. Furthermore, we successfully identified miR-21 and cytokines in the plasma samples. Notably, our analysis of Interleukin 6 (IL-6) unveiled higher expression in the clear cell subtype compared to the other types. Despite the ongoing research, the clinical implementation of liquid biopsy in meningiomas remains somewhat limited. Nevertheless, our promising results underscore the need for further investigation.

MicroRNA-126 in dogs with immune complex-mediated glomerulonephritis

BACKGROUND

Most proteinuric dogs with naturally occurring chronic kidney disease have amyloidosis (AMYL), glomerulosclerosis (GS), or immune complex-mediated glomerulonephritis (ICGN), each with different treatment and prognosis. A noninvasive and disease-specific biomarker is lacking.

HYPOTHESIS

We hypothesized that the expression pattern of biofluid microRNA (miRNAs and miRs) would correlate with disease progression and categorization.

ANIMALS

Archived serum and urine samples from 18 dogs with glomerular disease and 6 clinically healthy dogs; archived urine samples from 49 dogs with glomerular disease and 13 clinically healthy dogs.

METHODS

Retrospective study. Archived biofluid samples from adult dogs with biopsy-confirmed glomerular disease submitted to the International Veterinary Renal Pathology Service between 2008 and 2016 were selected. Serum and urinary miRNAs were isolated and profiled using RNA sequencing. Urinary miR-126, miR-21, miR-182, and miR-486 were quantified using quantitative reverse transcription PCR.

RESULTS

When comparing more advanced disease with earlier disease, no serum miRNAs were differentially expressed, but urinary miR-21 and miR-182 were 1.63 (95% CI: .86-3.1) and 1.45 (95% CI: .82-2.6) times higher in azotemic dogs, respectively (adjusted P < .05) and weakly correlated with tubulointerstitial fibrosis (miR-21: r = .32, P = .03; miR-182: r = .28, P = .05). Expression of urinary miR-126 was 10.5 (95% CI: 4.1-26.7), 28.9 (95% CI: 10.5-79.8), and 126.2 (95% CI: 44.7-356.3) times higher in dogs with ICGN compared with dogs with GS, AMYL, and healthy controls, respectively (P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

The miR-126 could help identify dogs that might benefit from immunosuppressive therapy in the absence of a biopsy. MiR-21 and miR-182 are potential markers of disease severity and fibrosis.

Expression of miR-21 &IL-4 in endometriosis

BACKGROUND

Endometriosis characterized with existence of endometrial-like tissue outside the uterus. Fibrosis of ectopic lesions is an important feature of endometriosis. IL-4 induces fibrosis via fibroblast proliferation, collagen production and myofibroblast differentiation. Increasing of miR-21 expression promotes fibroblast activation and fibrosis expansion. The aim of study was to evaluate the expression of miR-21 and its relationship with IL-4 gene expression in endometrial ectopic and eutopic tissues of endometriosis patients.

METHODS AND RESULTS

Ectopic and eutopic tissue samples were taken from 20 women with endometriosis, and control samples were taken from the endometrium of 20 endometriosis-free women. The relative expression of IL-4 and miR-21 evaluated by Real Time PCR. IL-4 relative gene expression was significantly increased in ectopic tissue compared to eutopic (p = 0.025) and control tissue (p = 0.021). The relative expression of miR-21 gene in ectopic tissue was increased compared to eutopic (p = 0.850) and control tissue (p = 0.978) but these differences were not significant. Also, the correlation between IL-4 and miR-21 relative gene expression was not significant (p = 0.083).

CONCLUSION

The increased expression of miR-21 in endometrium of women with endometriosis may upregulate the IL-4 gene expression and lead to fibrosis. Further studies may suggest miR-21 and IL-4 as candidates for diagnosis of endometriosis.

Prolonged Antibiotic Use in a Preclinical Model of Gulf War Chronic Multisymptom-Illness Causes Renal Fibrosis-like Pathology via Increased micro-RNA 21-Induced PTEN Inhibition That Is Correlated with Low Host Lachnospiraceae Abundance

Gulf War (GW) veterans show gastrointestinal disturbances and gut dysbiosis. Prolonged antibiotic treatments commonly employed in veterans, especially the use of fluoroquinolones and aminoglycosides, have also been associated with dysbiosis. This study investigates the effect of prolonged antibiotic exposure on risks of adverse renal pathology and its association with gut bacterial species abundance in underlying GWI and aims to uncover the molecular mechanisms leading to possible renal dysfunction with aging. Using a GWI mouse model, administration of a prolonged antibiotic regimen involving neomycin and enrofloxacin treatment for 5 months showed an exacerbated renal inflammation with increased NF-κB activation and pro-inflammatory cytokines levels. Involvement of the high mobility group 1 (HMGB1)-mediated receptor for advanced glycation end products (RAGE) activation triggered an inflammatory phenotype and increased transforming growth factor-β (TGF-β) production. Mechanistically, TGF-β- induced microRNA-21 upregulation in the renal tissue leads to decreased phosphatase and tensin homolog (PTEN) expression. The above event led to the activation of protein kinase-B (AKT) signaling, resulting in increased fibronectin production and fibrosis-like pathology. Importantly, the increased miR-21 was associated with low levels of Lachnospiraceae in the host gut which is also a key to heightened HMGB1-mediated inflammation. Overall, though correlative, the study highlights the complex interplay between GWI, host gut dysbiosis, prolonged antibiotics usage, and renal pathology via miR-21/PTEN/AKT signaling.

[Lithocholic acid decreases mRNA stability of nuclear receptor PPARα by upregulating miR-21 expression in hepatoma HepG2 cells]

OBJECTIVE

To investigate the regulatory effects of lithocholic acid (LCA) on nuclear receptor peroxisome proliferatoractivated receptor-alpha (PPARα) mRNA stability at the post-transcriptional level.

METHODS

PPARα 3'UTR luciferase reporter gene vectors were constructed and transfected into HepG2 cells to observe the changes in cellular luciferase activity in response to LCA treatments. Bioinformatic prediction and miRNA PCR array technique were used to identify the differentially expressed miRNAs induced by LCA and their potential binding sites on the 3'UTR. The binding sites (Mut1, Mut2 and Mut1+Mut2) were mutated to compare the changes in cellular luciferase activity following LCA treatment. Western blotting and RTqPCR were used to detect the activated signaling pathway and the expression levels of its downstream transcription factors in LCA-treated cells. The changes in PPARα protein expression level were detected in the cells following overexpression of the transcription factors.

RESULTS

Treatment with 100 μmol/L LCA significantly reduced luciferase activity of PPARα 3'UTR1 and 3'UTR2 in HepG2 cells by more than 50% (P<0.01) and induced significant upregulation of miR-21 and miR-22, especially the former (by 2.35 folds, P<0.05). Two predicted miR-21-binding sites in the 3'UTR1 were mutated to construct Mut1, Mut2 and Mut1+Mut2 reporter gene vectors. LCA treatment down-regulated 3'UTR1 luciferase activity by 51%, while Mut1, Mut2, and Mut1+Mut2 were down-regulated by 37%, 39%, and 13%, respectively. LCA caused ERK1/2 phosphorylation and activation of the ERK1/2 signaling pathway, and treatment with 100 μmol/L LCA upregulated the expression of transcription factor early growth response 1 (EGR1) by 5.83 folds (P<0.01). Transient overexpression of EGR1 significantly decreased cellular PPARα protein levels (P<0.05).

CONCLUSION

LCA reduces PPARα mRNA stability and thus decreases PPARα mRNA and protein expressions in hepatocytes by activating the ERK1/2 signaling pathway and upregulating EGR1 and miR-21, which targets 3'UTR regulatory region of PPARα mRNA.

miR-21 Expressed by Dermal Fibroblasts Enhances Skin Wound Healing Through the Regulation of Inflammatory Cytokine Expression

The management of skin wound healing is still a challenge. MicroRNA-21 (miR-21) has been reported to play important roles in wound repair; however, the underlying mechanism needs to be further clarified. The present study aimed to study the direct role of miR-21 in skin wound healing in miR-21 KO mice and to investigate the role of miR-21 in controlling the migration and proliferation of primary human skin cells and its underlying mechanism(s). miR-21 KO and wild-type (WT) mice were used for in vivo wound healing assays, while mouse and human primary skin cells were used for in vitro assays. miR-21 inhibitors or mimics or negative control small RNAs were transfected to either inhibit or enhance miR-21 expression in the human primary dermal fibroblasts or epidermal cells. RNA sequencing analysis was performed to identify the potential molecular pathways involved. We found that the loss of miR-21 resulted in slower wound healing in miR-21 KO mouse skin and especially delayed the healing of dermal tissue. In vitro assays demonstrated that the reduced expression of miR-21 caused by its inhibitor inhibited the migration of human primary dermal fibroblasts, which could be enhanced by increased miR-21 expression caused by miR-21 mimics. RNA-sequence analysis revealed that the inhibition of miR-21 expression downregulated the inflammatory response pathways associated with the decreased expression of inflammatory cytokines, and the addition of IL-1β into the culture medium enhanced the migration and proliferation of dermal fibroblasts in vitro. In conclusion, miR-21 in dermal fibroblasts can promote the migration and growth of epidermal and dermal cells to enhance skin wound healing through controlling the expression of inflammatory cytokines.

Differential effects of microRNAs miR-21, miR-99 and miR-145 on lung regeneration and inflammation during recovery from influenza pneumonia

In a mouse model of influenza pneumonia, we previously documented that proliferating alveolar type II (AT2) cells are the major stem cells involved in early lung recovery. Profiling of microRNAs revealed significant dysregulation of specific ones, including miR-21 and miR-99a. Moreover, miR-145 is known to exhibit antagonism to miR-21. This follow-up study investigated the roles of microRNAs miR-21, miR-99a, and miR-145 in the murine pulmonary regenerative process and inflammation during influenza pneumonia. Inhibition of miR-21 resulted in severe morbidity, and in significantly decreased proliferating AT2 cells due to impaired transition from innate to adaptive immune responses. Knockdown of miR-99a culminated in moderate morbidity, with a significant increase in proliferating AT2 cells that may be linked to PTEN downregulation. In contrast, miR-145 antagonism did not impact morbidity nor the proliferating AT2 cell population, and was associated with downregulation of TNF-alpha, IL1-beta, YM1, and LY6G. Hence, a complex interplay exists between expression of specific miRNAs, lung regeneration, and inflammation during recovery from influenza pneumonia. Inhibition of miR-21 and miR-99a (but not miR-145) can lead to deleterious cellular and molecular effects on pulmonary repair and inflammatory processes during influenza pneumonia.

Graph neural networks for the identification of novel inhibitors of a small RNA

MicroRNAs (miRNAs) play a crucial role in post-transcriptional gene regulation and have been implicated in various diseases, including cancers and lung disease. In recent years, Graph Neural Networks (GNNs) have emerged as powerful tools for analyzing graph-structured data, making them well-suited for the analysis of molecular structures. In this work, we explore the application of GNNs in ligand-based drug screening for small molecules targeting miR-21. By representing a known dataset of small molecules targeting miR-21 as graphs, GNNs can learn complex relationships between their structures and activities, enabling the prediction of potential miRNA-targeting small molecules by capturing the structural features and similarity between known miRNA-targeting compounds. The use of GNNs in miRNA-targeting drug screening holds promise for the discovery of novel therapeutic agents and provides a computational framework for efficient screening of large chemical libraries.

Metformin mediates MicroRNA-21 regulated circulating matrix metalloproteinase-9 in diabetic nephropathy: an in-silico and clinical study

Metformin is commonly used as an oral hypoglycaemic agent in type 2 diabetes mellitus (T2DM). MicroRNA-21 is widely studied in diabetic and diabetic nephropathy (DN) patients. Matrix metalloproteinase-9 (MMP9) is involved in extracellular matrix degradation and tissue repair processes. However, the effect of metformin administration on hsa-miR-21-5p and MMP9 has not been evaluated in T2DM and DN patients. The study subjects were divided into three groups (Healthy controls = 36, T2DM = 38, DN = 35). Anthropometric measurements were taken and biochemical tests were carried out on fasting blood samples. Reverse transcriptase PCR was employed for whole blood gene expression analysis of hsa-miR-21-5p and MMP9. Bioinformatics analyses including drug-gene interaction, protein-protein interaction, functional enrichment analyses and co-expression networks were performed. In the present study, MMP9 and hsa-miR-21-5p levels were downregulated and upregulated respectively in T2DM and DN patients when compared with healthy controls. However, in metformin-treated group, a downregulation of hsa-miR-21-5p and upregulation of MMP9 was observed. In-silico analysis revealed the target genes involved in the miR-21 and MMP9 interaction network. Metformin directly targets miR-21 and regulates MMP9 expression in T2DM patients, influencing the pathogenesis of DN.HighlightsMMP-9 and hsa-miR-21-5p were downregulated and upregulated respectively in T2DM and DN patients in a Western Indian population.The patients treated with metformin showed downregulation of hsa-miR-21-5p and upregulation of MMP9.In-silico analysis revealed MMP-9 as well as PTEN to be targets of hsa-miR-21-5p.Metformin regulates MMP9 expression in T2DM and DN patient populations through hsa-miR-21-5p.

MiR-21 regulated hair follicle cycle development in Cashmere goats by targeting FGF18 and SMAD7

Increasing Cashmere production can add value because it is the primary product of Cashmere goats. Recent years, peoples find miRNAs are crucial in regulating the development of hair follicle. Following Solexa sequencing, many miRNAs were distinguishingly expressed in telogen skin samples of goats and sheep in earlier study. But the method through which miR-21 controls the growth of hair follicles is still ambiguous. Bioinformatics analysis was used to predict the target genes of miR-21. The mRNA level of miR-21 in telogen Cashmere goat skins was higher than in anagen, according to the results of qRT-PCR, and the target genes expressed similarly with miR-21. Western blot showed similar trend, the protein expression of FGF18 and SMAD7 were lower in anagen samples. The Dual-Luciferase reporter assay confirmed miRNA-21's relationship with its target gene, and the consequences indicated found FGF18 and SMAD7 have positive correlations with miR-21. Western blot and qRT-PCR distinguished the expression of protein and mRNA in miR-21 and its target genes. According to the consequence, we found that target genes expression was increased by miR-21 in HaCaT cells. This study identified that miR-21 might take part in the development of Cashmere goat's hair follicles by targeting FGF18 and SMAD7.

A PRISMA meta-analysis for diagnostic value of microRNA-21 in head and neck squamous cell carcinoma along with bioinformatics research

OBJECTIVES

The use of miR-21 expression remains vague in diagnosis of head and neck squamous cell carcinoma (HNSCC). This study aimed to systematically evaluate the diagnostic potential of the miR-21 expression in patients with HNSCCs through investigating and summarizing the results reported in the literature.

METHODS

Extant medical databases were examined for articles of clinical study assessing the miR-21 expression in HNSCC cases, published in the past 20 years. Bioinformatics research was also performed for finding miR-21 targets differentially expressed in HNSCC so as to present their biological behaviors.

RESULTS

Our meta-analysis comprised 11 studies including 622/450 cases in HNSCC/control group. Forest plots displayed miR-21 which possessed significantly good specificity (0.76, p < 0.001) and sensitivity (0.80, p < 0.001). Diagnostic odds ratio was 2.46 (95% CI 1.87-3.24). Positive and negative likelihood ratio was 3.40 (95% CI 1.94-5.97) and 0.26 (95% CI 0.18-0.38), respectively. Area under the receiver operating characteristic curve was 0.85.

CONCLUSION

This study is the highest level of evidence presently available in diagnosing HNSCC. This PRISMA meta-analysis indicated that the pooled results were robust, confirming the oncogenic potential of miR-21 that could be used successfully as a screening biomarker in HNSCC patients. Specifically, the overexpression of miR-21 in these patients presents a worse survival outcome.

The relationship between miR-21, DNA methylation, and bisphenol a in bovine COCs and granulosa cells

Introduction: miR-21 is a critical microRNA for the regulation of various processes in oocytes and granulosa cells. It is involved in the modulation of apoptosis and can influence other epigenetic mechanisms. Among these mechanisms, DNA methylation holds significant importance, particularly during female gametogenesis. Evidence has demonstrated that microRNAs, including miR-21, can regulate DNA methylation. Bisphenol A (BPA) is a widespread chemical that disrupts oocyte maturation and granulosa cell function. Recent findings suggested that BPA can act through epigenetic pathways, including DNA methylation and microRNAs. Methods: This study uses anti-miR-21 LNAs to explore the involvement of miR-21 in the regulation of DNA methylation in bovine Cumulus-Oocyte-Complexes (COCs) and granulosa cells, in the presence and absence of BPA. This study investigated 5 mC/5hmC levels as well as gene expression of various methylation enzymes using qPCR and western blotting. Results and discussion: Results reveal that BPA reduces 5mC levels in granulosa cells but not in COCs, which can be attributed to a decrease in the methylating enzymes DNMT1 and DNMT3A, and an increase in the demethylating enzyme TET2. We observed a significant increase in the protein levels of DNMT1, DNMT3A, and TET2 upon inhibition of miR-21 in both COCs and granulosa cells. These findings directly imply a strong correlation between miR-21 signaling and the regulation of DNA methylation in bovine COCs and granulosa cells under BPA exposure.

Upregulation of miR-21 and pro-inflammatory cytokine genes IL-6 and TNF-α in promoting a pro-tumorigenic microenvironment in canine mammary carcinomas

This study evaluated the gene expression of the pro-inflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in canine mammary tumors (CMTs), and correlated them with gene expression of miRNAs expected to regulate the secretion of pro-inflammatory cytokines within the tumor microenvironment (TME). Furthermore, gene expression of cytokines and miRNAs involved in tumor cell proliferation and invasion (i.e. miR-21; miR-124; miR-145) were correlated with tumor proliferation index (Ki67 index) to determine the prognostic value in CMTs. Twenty-six canine mammary samples were used, including 22 CMTs and 4 control samples. MiR-21, IL-6 and TNF-α were upregulated in mammary carcinomas compared with controls (p < 0.05). MiR-146b was downregulated in CMTs compared with control cases (p < 0.05). IL-6 expression showed a significant positive correlation with miR-21 and a negative correlation with miR-146b; while, TNF-α gene expression was positively correlated with miR-21 and miR-145 in mammary carcinomas. In carcinomas, the Ki67 index correlated positively with gene expression of IL-6 and miR-21 and negatively correlated with miR-145 and miR-146b. Specifically, gene expression of IL-6 and miR-21 was positively correlated with ki67 index >33.3%, whereas, expression of miR-145 and miR-146b was negatively correlated with ki67 index <33.3%. Results reinforce the concept of interaction between tumor cells and inflammatory cells within the TME, with a central role of IL-6 and TNF-α. Since the upregulation of miR-21 reflects the gene overexpression of interleukins and the high proliferation index of tumor cells, this miRNA may be considered a biomarker with prognostic value in CMTs.

SNHG1/miR-21 axis mediates the cardioprotective role of aloin in sepsis through modulating cardiac cell viability and inflammatory responses

BACKGROUND

Aloin has cardioprotective effects, however, its cardioprotective role in sepsis remains unclear. This study aimed to analyze whether aloin could prevent sepsis-related myocardial damage and explore the underlying mechanisms by examining the expression of long-noncoding RNA (lncRNA) SNHG1 and microRNA-21 (miR-21).

METHODS

The interaction of SNHG1 with miR-21 was identified by dual-luciferase reporter assay. The levels of SNHG1 and miR-21 were measured by real-time quantitative PCR. The cardioprotective function of aloin was assessed in a sepsis animal model, which was induced by cecal ligation and puncture, and in a myocardial injury cell model in H9C2 cells stimulated by lipopolysaccharide. Myocardial injury biomarker levels and hemodynamic indicators in mice model were measured to evaluate cardiac function. The viability of H9C2 cells was assessed by cell counting kit-8 assay. Inflammatory cytokine levels were examined by an ELISA method.

RESULTS

Decreased SNHG1 and increased miR-21 were found in sepsis patients with cardiac dysfunction, and they were negatively correlated. Aloin significantly attenuated myocardial damage and inflammatory responses of mice model, and increased the viability and suppressed inflammation in H9C2 cell model. In addition, SNHG1 expression was upregulated and miR-21 expression was downregulated by aloin in both mice and cell models. Moreover, in mice and cell models, SNHG1/miR-21 axis affected sepsis-related myocardial damage, and mediated the cardioprotective effects of aloin.

CONCLUSION

Our findings indicated that aloin exerts protective effects in sepsis-related myocardial damage through regulating cardiac cell viability and inflammatory responses via regulating the SNHG1/miR-21 axis.

The Effect of Gene Editing by CRISPR-Cas9 of miR-21 and the Indirect Target MMP9 in Metastatic Prostate Cancer

Prostate cancer (PCa) has a high prevalence and represents an important health problem, with an increased risk of metastasis. With the advance of CRISPR-Cas9 genome editing, new possibilities have been created for investigating PCa. The technique is effective in knockout oncogenes, reducing tumor resistance. MMP9 and miR-21 target genes are associated with PCa progression; therefore, we evaluated the MMP-9 and miR-21 targets in PCa using the CRISPR-Cas9 system. Single guide RNAs (sgRNAs) of MMP9 and miR-21 sequences were inserted into a PX-330 plasmid, and transfected in DU145 and PC-3 PCa cell lines. MMP9 and RECK expression was assessed by qPCR, WB, and IF. The miR-21 targets, integrins, BAX and mTOR, were evaluated by qPCR. Flow cytometry was performed with Annexin5, 7-AAD and Ki67 markers. Invasion assays were performed with Matrigel. The miR-21 CRISPR-Cas9-edited cells upregulated RECK, MARCKS, BTG2, and PDCD4. CDH1, ITGB3 and ITGB1 were increased in MMP9 and miR-21 CRISPR-Cas9-edited cells. Increased BAX and decreased mTOR were observed in MMP9 and miR-21 CRISPR-Cas9-edited cells. Reduced cell proliferation, increased apoptosis and low invasion in MMP9 and miR-21 edited cells was observed, compared to Scramble. CRISPR-Cas9-edited cells of miR-21 and MMP9 attenuate cell proliferation, invasion and stimulate apoptosis, impeding PCa evolution.

Rapid and sensitive detection of miRNA via light scatter-aided emulsion-based isothermal amplification using a custom low-cost device

MicroRNAs are likely to be a next-generation clinical biomarker for many diseases. While gold-standard technologies, e.g., reverse transcription-quantitative polymerase chain reaction (RT-qPCR), exist for microRNA detection, there is a need for rapid and low-cost testing. Here, an emulsion loop-mediated isothermal amplification (eLAMP) assay was developed for miRNA that compartmentalizes a LAMP reaction and shortens the time-to-detection. The miRNA was a primer to facilitate the overall amplification rate of template DNA. Light scatter intensity decreased when the emulsion droplet got smaller during the ongoing amplification, which was utilized to moitor the amplification non-invasively. A custom low-cost device was designed and fabricated using a computer cooling fan, a Peltier heater, an LED, a photoresistor, and a temperature controller. It allowed more stable vortexing and accurate light scatter detection. Three miRNAs, miR-21, miR-16, and miR-192, were successfully detected using the custom device. Specifically, new template and primer sequences were developed for miR-16 and miR-192. Zeta potential measurements and microscopic observations confirmed emulsion size reduction and amplicon adsorption. The detection limit was 0.01 fM, corresponding to 2.4 copies per reaction, and the detection could be made in 5 min. Since the assays were rapid and both template and miRNA + template could eventually be amplified, we introduced the success rate (compared to the 95% confidence interval of the template result) as a new measure, which worked well with lower concentrations and inefficient amplifications. This assay brings us one step closer to allowing circulating miRNA biomarker detection to become commonplace in the clinical world.

Promising renoprotective effect of gold nanoparticles and dapagliflozin in diabetic nephropathy via targeting miR-192 and miR-21

Diabetic nephropathy (DN) is a worldwide issue that eventually leads to end-stage renal failure, with limited therapeutic options. Prior research has revealed that gold nanoparticles (AuNPs) have a substantial antidiabetic impact. In addition, sodium-glucose cotransporter2 (SGLT2) inhibitors, including dapagliflozin (DAPA), had renoprotective impact on DN. Therefore, this research attempted to determine the potential AuNPs and DAPA impacts in ameliorating experimentally DN induction and the underlying mechanisms focusing on miR-192 and miR-21, correlating them with autophagy, apoptosis, fibrosis, and oxidative stress. Diabetes induction was through a single intraperitoneal streptozotocin (55 mg/kg) injection, and rats with diabetes received AuNPs (2.5 mg/kg/day) as well as DAPA (2 mg/kg/day) for 7 weeks as a treatment. AuNPs and DAPA treatment for 7 weeks substantially alleviated DN. AuNPs and DAPA significantly increased catalase (CAT) activity as well as serum total antioxidant capacity (TAC), along with a substantial decline in malondialdehyde (MDA). AuNPs and DAPA treatment alleviated renal fibrosis as they decreased transforming growth factorß1(TGF-ß1) as well as matrix metalloproteinase-2 (MMP-2) renal expression, decreased apoptosis through alleviating the proapoptotic gene (caspase-3) renal expression and increased the antiapoptotic gene (Bcl-2) renal expression, and increased autophagy as they increased LC-3 as well as Beclin-1 renal expression. Autophagy activation, inhibition of apoptosis, and renal fibrosis could be due to their inhibitory impact on miR-192 and miR-21 renal expression. AuNPs and DAPA have a protective effect on DN in rats by targeting miR-192 and miR-21 and their downstream pathways, including fibrosis, apoptosis, autophagy, and oxidative stress.

Circulating miR-146a predicts glucocorticoid response in thyroid eye disease

Objective

Thyroid eye disease (TED) is an immune-mediated disorder of the eye. Intravenous glucocorticoid (GC) is the first-line treatment for patients with active moderate-to-severe TED. However, the response rate is between 50% and 80%. There are still no simple and reliable markers of responsiveness to GC therapy. We aimed to explore the possible role of miR-146a and miR-21 as predictors of responsiveness to GC treatment in TED.

Methods

We carried out a prospective longitudinal study on 30 consecutive adult patients with active moderate-to-severe TED and eligible for GC therapy. All patients received the standard GC treatment with methylprednisolone i.v. In cases of progressive worsening of Gorman Score for diplopia or with duction restriction <30° in at least two consecutive controls, patients also underwent orbital radiotherapy. Response to GC treatment was defined as a decrease of two or more points in the clinical activity score (CAS) or CAS <4/10 at 24 weeks. Circulating miRNAs were extracted from patients' serum and quantified by real-time PCR.

Results

Twenty-three (77%) patients responded to GC. Thyroid surgery, higher CAS, greater proptosis and higher pre-treatment circulating levels of miR-146a emerged as predictive factors of responsiveness to GC. A ROC analysis revealed that miR-146a could predict responsiveness to GC with a positive predictive value of 100%.

Conclusion

This is the first study investigating the role of pre-treatment circulating miR-21 and miR-146a to predict responsiveness to GC in TED. miR-146a emerged as a simple, objective, new marker of GC sensitivity that could be used to avoid ineffective administration of GC therapy to TED patients.

Milk-Derived Small Extracellular Vesicles Promote Osteogenic Differentiation and Inhibit Inflammation via microRNA-21

Chronic apical periodontitis (CAP) is a disease with characteristics of inflammation and bone loss. In this study, our objective was to examine the function of small extracellular vesicles (sEVs) obtained from milk in encouraging osteogenic differentiation and inhibiting inflammation by miR-21 in CAP. The expression of miR-21 was detected using qRT-PCR in human CAP samples. The impact of miR-21 on the process of osteogenic differentiation was investigated using CCK-8, qRT-PCR, immunofluorescence staining, and Western blot analysis. The evaluation of RAW 264.7 cell polarization and the assessment of inflammatory factor expression were conducted through qRT-PCR. The influence of sEVs on MC3T3-E1 cells and RAW 264.7 cells was examined, with a particular emphasis on the involvement of miR-21. In human CAP samples, a decrease in miR-21 expression was observed. MiR-21 increased the expression of osteogenesis-related genes and M2 polarization genes while decreasing the expression of M1 polarization genes and inflammatory cytokines. Treatment with milk-derived sEVs also promoted osteogenesis and M2 polarization while inhibiting M1 polarization and inflammation. Conversely, the addition of miR-21 inhibitors resulted in opposite effects. Our results indicated that sEVs derived from milk had a positive effect on bone formation and activation of anti-inflammatory (M2) macrophages and simultaneously reduced inflammation by regulating miR-21 in CAP.

TLR7 activation by miR-21 promotes renal fibrosis by activating the pro-inflammatory signaling pathway in tubule epithelial cells

BACKGROUND

Toll-like receptor 7 (TLR7) is an endosomal TLR activated by single-stranded RNA, including endogenous microRNAs. Although TLR7 is known to promote inflammatory responses in pathophysiological conditions, its role in renal fibrosis has not been investigated. Here, we aim to investigate the inflammatory roles of TLR7 in kidney inflammation and fibrosis.

METHODS

TLR7 knockout mice (Tlr7 -/-) subjected to AD-induced kidney injury were utilized to examine the role of TLR7 in kidney fibrosis. To elucidate the role of TLR7 in renal epithelial cells, NRK52E rat renal tubule epithelial cells were employed.

RESULTS

Under fibrotic conditions induced by an adenine diet (AD), TLR7 was significantly increased in damaged tubule epithelial cells, where macrophages were highly infiltrated. TLR7 deficiency protected against AD-induced tubular damage, inflammation, and renal fibrosis. Under in vitro conditions, TLR7 activation increased NF-κB activity and induced chemokine expression, whereas TLR7 inhibition effectively blocked NF-κB activation. Furthermore, among the known TLR7 endogenous ligands, miR-21 was significantly upregulated in the tubular epithelial regions. In NRK52E cells, miR-21 treatment induced pro-inflammatory responses, which could be blocked by a TLR7 inhibitor. When the TLR7 inhibitor, M5049, was administered to the AD-induced renal fibrosis model, TLR7 inhibition significantly attenuated AD-induced renal inflammation and fibrosis.

CONCLUSIONS

Overall, activation of TLR7 by endogenous miR-21 in renal epithelial cells contributes to inflammatory responses in a renal fibrosis model, suggesting a possible therapeutic target for the treatment of renal fibrosis. Video Abstract.

Mesenchymal stem cells, as glioma exosomal immunosuppressive signal multipliers, enhance MDSCs immunosuppressive activity through the miR-21/SP1/DNMT1 positive feedback loop

BACKGROUND

The immunosuppressive microenvironment in glioma induces immunotherapy resistance and is associated with poor prognosis. Glioma-associated mesenchymal stem cells (GA-MSCs) play an important role in the formation of the immunosuppressive microenvironment, but the mechanism is still not clear.

RESULTS

We found that GA-MSCs promoted the expression of CD73, an ectonucleotidase that drives immunosuppressive microenvironment maintenance by generating adenosine, on myeloid-derived suppressor cells (MDSCs) through immunosuppressive exosomal miR-21 signaling. This process was similar to the immunosuppressive signaling mediated by glioma exosomal miR-21 but more intense. Further study showed that the miR-21/SP1/DNMT1 positive feedback loop in MSCs triggered by glioma exosomal CD44 upregulated MSC exosomal miR-21 expression, amplifying the glioma exosomal immunosuppressive signal. Modified dendritic cell-derived exosomes (Dex) carrying miR-21 inhibitors could target GA-MSCs and reduce CD73 expression on MDSCs, synergizing with anti-PD-1 monoclonal antibody (mAb).

CONCLUSIONS

Overall, this work reveals the critical role of MSCs in the glioma microenvironment as signal multipliers to enhance immunosuppressive signaling of glioma exosomes, and disrupting the positive feedback loop in MSCs with modified Dex could improve PD-1 blockade therapy.

Micro RNAs as a Diagnostic Marker between Glioma and Primary CNS Lymphoma: A Systematic Review

Differentiating glioma from primary central nervous system lymphoma (PCNSL) can be challenging, and current diagnostic measures such as MRI and biopsy are of limited efficacy. Liquid biopsies, which detect circulating biomarkers such as microRNAs (miRs), may provide valuable insights into diagnostic biomarkers for improved discrimination. This review aimed to investigate the role of specific miRs in diagnosing and differentiating glioma from PCNSL. A systematic search was conducted of PubMed, Scopus, Web of Science, and Embase for articles on liquid biopsies as a diagnostic method for glioma and PCNSL. Sixteen dysregulated miRs were identified with significantly different levels in glioma and PCNSL, including miR-21, which was the most prominent miR with higher levels in PCNSL, followed by glioma, including glioblastoma (GBM), and control groups. The lowest levels of miR-16 and miR-205 were observed in glioma, followed by PCNSL and control groups, whereas miR-15b and miR-301 were higher in both tumor groups, with the highest levels observed in glioma patients. The levels of miR-711 were higher in glioma (including GBM) and downregulated in PCNSL compared to the control group. This review suggests that using these six circulating microRNAs as liquid biomarkers with unique changing patterns could aid in better discrimination between glioma, especially GBM, and PCNSL.

A novel Telomerase activity and microRNA-21 upregulation identified in a family with Palmoplantar keratoderma

Palmoplantar keratoderma is a set of skin diseases with hyperkeratotic thickening of palms and soles which are characteristic of these heterogeneous group of keratinization disorders. Various genetic mutations, autosomal dominant or recessive, have been identified which may triggerpalmoplantar keratoderma, as KRT9 (Keratin 9), KRT1 (Keratin1), AQP5 (Aquaporin), SERPINB 7 (serine protease inhibitor). The identification of causal mutations is extremely important for the correct diagnosis. Here, we report the case of a family affected from Palmoplantar keratoderma caused by autosomal dominant KRT1 mutations (Unna-Thost disease). Telomerase activation and hTERT expression take a part in the process of cell proliferation and inflammation and microRNAs, as microRNA-21, are emerging as drivers in the regulation of telomerase activity. Here, the patients underwent KRT1 analysis genetic sequence, telomerase activity and miR-21 expression. Beside histopathology assay was performed. The patients presented thickening of the skin on soles of the feet and the palms of the hands, KRT1mutations and showed high expression levels of hTERT and hTR, the gene encoding for the telomeric subunits, and miR-21 (fold change >1.5 and p value =0.043), explicating the aberrant proliferation of epidermal layer and the inflammatory state characterizing palmoplantar keratoderma.

The Potential of miR-21 in Stem Cell Differentiation and its Application in Tissue Engineering and Regenerative Medicine

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two important types of non-coding RNAs that are not translated into protein. These molecules can regulate various biological processes, including stem cell differentiation and self-renewal. One of the first known miRNAs in mammals is miR-21. Cancer-related studies have shown that this miRNA has proto-oncogene activity and is elevated in cancers. However, it is confirmed that miR-21 inhibits stem cell pluripotency and self-renewal and induces differentiation by targeting various genes. Regenerative medicine is a field of medical science that tries to regenerate and repair damaged tissues. Various studies have shown that miR-21 plays an essential role in regenerative medicine by affecting stem cell proliferation and differentiation. In this review, we will discuss the function of miR-21 in regenerative medicine of the liver, nerve, spinal cord, wound, bone, and dental tissues. In addition, the function of natural compounds and lncRNAs will be analyzed as potential regulators of miR-21 expression in regenerative medicine.

Geraniol suppresses tumour growth and enhances chemosensitivity of 5-fluorouracil on breast carcinoma in mice: involvement of miR-21/PTEN signalling

OBJECTIVES

Breast cancer is the most diagnosed cancer in females worldwide. Phytochemicals are among the recent compelling approaches showing anticancer activity. Geraniol is a monoterpenoid showing anti-tumoral potential in cell lines. However, its exact mechanism in breast cancer has not been elucidated. In addition, the possible chemosenstizing effect of geraniol when combined with chemotherapeutic drugs in breast carcinoma has not been previously addressed.

METHODS

Therefore, the aim of the current work is to investigate the potential therapeutic as well as chemosensitizing effects of geraniol on breast carcinoma induced in mice through examination of tumour biomarkers and histopathology profile.

KEY FINDINGS

Results showed a prominent suppression of tumour growth following geraniol treatment. This was accompanied with miR-21 downregulation that subsequently upregulated PTEN and suppressed mTOR levels. Geraniol was also able to activate apoptosis and inhibit autophagy. Histopathological examination revealed high necrosis areas separating malignant cells in the geraniol-treated group. Combined geraniol and 5-fluorouracil treatment induced more than 82% inhibition of tumour rate, surpassing the effect of each drug alone.

CONCLUSIONS

It can be concluded that geraniol could represent a promising avenue for breast cancer treatment as well as a potential sensitizing agent when combined with chemotherapeutic drugs.

Delivery of anti-microRNA-21 by lung-targeted liposomes for pulmonary fibrosis treatment

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disorder with a low survival rate. Pulmonary fibrosis is one of the complications of COVID-19 and has a high prevalence in COVID-19 patients. Currently, no effective therapies other than lung transplantation are available to cure IPF and post-COVID-19 pulmonary fibrosis. MicroRNAs are small non-coding RNAs that mediate the development and progression of pulmonary fibrosis, thus making them potent drug candidates for this serious disease. MicroRNA-21 (miR-21) promotes not only the differentiation of fibroblasts to myofibroblasts but also epithelial-mesenchymal transition, both of which have been proposed as fundamental processes in pulmonary fibrosis development. Delivery of anti-miR-21 to block the miR-21-associated fibrogenic pathways represents a promising therapy for pulmonary fibrosis. However, microRNA treatment is challenged by quick degradation of RNA in blood, poor cellular uptake, and off-target effects. To overcome these challenges, we developed a lung-targeted, cationic liposome formulation to encapsulate anti-miR-21, enhance its delivery efficiency, and improve the therapeutic efficacy. We optimized the liposome formulation and demonstrated the anti-fibrotic effects using both in vitro and in vivo lung fibrosis models. Our results showed that anti-miR-21 delivered by cationic liposomes suppressed myofibroblast differentiation, reduced the synthesis of extracellular matrix, and inhibited fibrosis progression.

Synthetic miR-21 decoy circularized by tRNA splicing mechanism inhibited tumorigenesis in glioblastoma in vitro and in vivo models

Glioblastoma multiforme (GBM) is the deadliest primary central nervous system tumor. miRNAs (miRs), a class of non-coding RNAs, are considered pivotal post-transcriptional regulators of cell signaling pathways. miR-21 is a reliable oncogene that promotes tumorigenesis of cancer cells. We first performed an in silico analysis on 10 microarray datasets retrieved from TCGA and GEO databases to elucidate top differentially expressed miRs. Furthermore, we generated a circular miR-21 decoy, CM21D, using the tRNA-splicing mechanism in GBM cell models, U87 and C6. The inhibitory efficacy of CM21D with that of a linear form, LM21D, was compared under in vitro conditions and an intracranial C6 rat glioblastoma model. miR-21 significantly overexpressed in GBM samples and confirmed in GBM cell models using qRT-PCR. CM21D was more efficient than LM21D at inducing apoptosis, inhibiting cell proliferation and migration, and interrupting the cell cycle by restoring the expression of miR-21 target genes at RNA and protein levels. Moreover, CM21D suppressed tumor growth more effectively than LM21D in the C6-rat GBM model (p < 0.001). Our findings validate miR-21 as a promising therapeutic target for GBM. The introduced CM21D by sponging miR-21 reduced tumorigenesis of GBM and can be considered a potential RNA-base therapy to inhibit cancers.

Validation of miRNAs as diagnostic and prognostic biomarkers, and possible therapeutic targets in medullary thyroid cancers

Introduction

Medullary thyroid cancer (MTC) is a rare type of neuroendocrine tumor that produces a hormone called calcitonin (CT). Thyroidectomy is the preferred treatment for MTC, as chemotherapy has been shown to have limited effectiveness. Targeted therapy approaches are currently being used for patients with advanced, metastatic MTC. Several studies have identified microRNAs, including miR-21, as playing a role in the development of MTC. Programmed cell death 4 (PDCD4) is a tumor suppressor gene that is an important target of miR-21. Our previous research has shown that high levels of miR-21 are associated with low PDCD4 nuclear scores and high CT levels. The aim of this study was to investigate the potential of this pathway as a novel therapeutic target for MTC.

Methods

We used a specific process to silence miR-21 in two human MTC cell lines. We studied the effect of this anti-miRNA process alone and in combination with cabozantinib and vandetanib, two drugs used in targeted therapy for MTC. We analyzed the effect of miR-21 silencing on cell viability, PDCD4 and CT expression, phosphorylation pathways, cell migration, cell cycle, and apoptosis.

Results

Silencing miR-21 alone resulted in a reduction of cell viability and an increase in PDCD4 levels at both mRNA and protein levels. It also led to a reduction in CT expression at both mRNA and secretion levels. When combined with cabozantinib and vandetanib, miR-21 silencing did not affect cell cycle or migration but was able to enhance apoptosis.

Conclusion

Silencing miR-21, although not showing synergistic activity with TKIs (tyrosine kinase inhibitors), represents a potential alternative worth exploring as a therapeutic target for MTC.

Nicotine Treatment Ameliorates Blood-Brain Barrier Damage After Acute Ischemic Stroke by Regulating Endothelial Scaffolding Protein Pdlim5

Analysis of a National Institutes of Health (NIH) trial shows that cigarette smoking protected tissue plasminogen activator (tPA)-treated patients from hemorrhage transformation (HT); however, the underlying mechanism is not clear. Damage to the integrity of the blood-brain barrier (BBB) is the pathological basis of HT. Here, we investigated the molecular events of BBB damage after acute ischemic stroke (AIS) using in vitro oxygen-glucose deprivation (OGD) and in vivo mice middle cerebral artery occlusion (MCAO) models. Our results showed that the permeability of bEND.3 monolayer endothelial cells was significantly increased after being exposed to OGD for 2 h. Mice were subjected to 90-min ischemia with 45-min reperfusion, and BBB integrity was significantly damaged, accompanied by tight junction protein occludin degradation, downregulation of microRNA-21 (miR-21), transforming growth factor-β (TGF-β), phosphorylated Smad (p-Smad), plasminogen activator inhibitor-1 (PAI-1), and the upregulation of PDZ and LIM domain protein 5 (Pdlim5), an adaptor protein that has been shown to regulate TGF-β-Smad3 pathway. In addition, pretreatment with two-week nicotine significantly reduced AIS-induced BBB damage and its associated protein dysregulation via downregulating Pdlim5. Notably, AIS did not significantly induce BBB damage in Pdlim5 deficit mice, but overexpression of Pdlim5 in the striatum with adeno-associated virus produced BBB damage and associated protein dysregulation which could be ameliorated by two-week nicotine pretreatment. More important, AIS induced a significant miR-21 decrease, and miR-21 mimics treatment decreased AIS-induced BBB damage by decreasing Pdlim5. Together, these results demonstrate that nicotine treatment alleviates the AIS-compromised integrity of BBB by regulating Pdlim5.

Circulating microRNAs for Early Diagnosis of Ovarian Cancer: A Systematic Review and Meta-Analysis

In this study, we conducted a systematic review and meta-analysis to summarize and evaluate the global research potential of different circulating miRNAs as an early diagnostic biomarker for OC. A systematic literature search for relevant studies was conducted in June 2020 and followed up in November 2021. The search was conducted in English databases (PubMed, ScienceDirect). The primary search resulted in a total of 1887 articles, which were screened according to the prior established inclusion and exclusion criteria. We identified 44 relevant studies, of which 22 were eligible for the quantitative meta-analysis. Statistical analysis was performed using the Meta-package in Rstudio. Standardized mean differences (SMD) of relative levels between control subjects and OC patients were used to evaluate the differential expression. All studies were quality evaluated using a Newcastle-Ottawa Scale. Based on the meta-analysis, nine miRNAs were identified as dysregulated in OC patients compared to controls. Nine were upregulated in OC patients compared to controls (miR-21, -125, -141, -145, -205, -328, -200a, -200b, -200c). Furthermore, miR-26, -93, -106 and -200a were analyzed, but did not present an overall significant difference between OC patients and controls. These observations should be considered when performing future studies of circulating miRNAs in relation to OC: sufficient size of clinical cohorts, development of consensus guidelines for circulating miRNA measurements, and coverage of previously reported miRNAs.

A universal lateral flow assay for microRNA visual detection in urine samples

MicroRNAs (miRNAs) have been emerged as novel and significant biomarkers in liquid biopsy that can be found in different body fluids. Several techniques have been developed and applied for miRNAs analysis, including nucleic acid-based amplification methods, next generation sequencing, DNA microarrays and new genome-editing methods. These methods, however, are time-consuming and require expensive instruments and specially trained personnel. Biosensors, on the other hand, are alternative and valuable analytical/diagnostic tools due to their simplicity, cost-effectiveness, rapid analysis and ease of use. Several biosensors, especially nanotechnology-based ones, have been developed for miRNA analysis that are based either on target amplification or signal amplification and target re-cycling for sensitive detection. At this point of view, we have introduced a new and universal lateral flow assay in combination with reverse transcription - polymerase chain reaction (RT-PCR) and gold nanoparticles as reporters for the detection of miR-21 and miR-let-7a in human urine. It is the first time that such a biosensor has been applied to the detection of microRNAs in urine. As low as 10²-10³ copies of miR-21 and 10^2--10⁴ copies of miR-let-7a added in urine were detectable by the proposed lateral flow assay with great specificity and repeatability (%CVs <4.5%).

MiR-21 alleviates renal tubular epithelial cells injury induced by ischemia by targeting TLR4

Renal ischemia is the initial stage of kidney damage, leading to mitochondrial metabolism disorders and cell necrosis. In this study, we aimed to investigate the biological functions and potential mechanisms of miR-21 in protecting renal tubular epithelial cells from oxidative stress and apoptosis following oxygen glucose deprivation (OGD). Following an OGD injury, miR-21 levels increased in HK-2 renal tubular epithelial cells. Overexpression of miR-21 decreased the protein expressions of cleaved caspase-3, BAX, P53, cell apoptosis and increased Bcl-2 expression in HK-2 cells with OGD injury. In vivo studies found that miR-21 agomir reduced renal tissue apoptosis, while miR-21 antagomir increased it. In addition, overexpression of miR-21 reduced levels of reactive oxygen species (ROS), malondialdehyde (MDA) and lactate dehydrogenase (LDH) in HK-2 cells with OGD injury. However, miR-21 inhibition exhibited the opposite effect. A dual-luciferase reporter assay demonstrated that miR-21 directly regulates Toll-like receptor 4 (TLR4) by targeting the 3'-UTR of TLR4 mRNA. Overexpression of miR-21 led to decreased TLR4 protein expression, and TLR4 knockdown was shown to greatly increase AKT activity in HK-2 cells by in vitro kinase assay. Additionally, TLR4 knockdown promoted AKT phosphorylation and hypoxia-inducible factor-1α (HIF-1α) expression, while TLR4 overexpression inhibited these processes. Furthermore, AKT activation abolished the effect of TLR4 on HIF-1α, while AKT inhibition decreased the expression of TLR4 on HIF-1α in TLR4 knockdown HK-2 cells. Further study revealed that HIF-1α inhibition abolished the protective effect of miR-21 overexpression on ROS, LDH levels and cell apoptosis in HK-2 cells after OGD injury, which is indicated by increased levels of ROS and LDH, as well as increased cell apoptosis after HIF-1α inhibition in miR-21-treated HK-2 cells. In conclusion, miR-21 defends OGD-induced HK-2 cell injury via the TLR4/AKT/HIF-1α axis.

Advances in Electrochemical Biosensor Technologies for the Detection of Nucleic Acid Breast Cancer Biomarkers

Breast cancer is the second leading cause of cancer deaths in women worldwide; therefore, there is an increased need for the discovery, development, optimization, and quantification of diagnostic biomarkers that can improve the disease diagnosis, prognosis, and therapeutic outcome. Circulating cell-free nucleic acids biomarkers such as microRNAs (miRNAs) and breast cancer susceptibility gene 1 (BRCA1) allow the characterization of the genetic features and screening breast cancer patients. Electrochemical biosensors offer excellent platforms for the detection of breast cancer biomarkers due to their high sensitivity and selectivity, low cost, use of small analyte volumes, and easy miniaturization. In this context, this article provides an exhaustive review concerning the electrochemical methods of characterization and quantification of different miRNAs and BRCA1 breast cancer biomarkers using electrochemical DNA biosensors based on the detection of hybridization events between a DNA or peptide nucleic acid probe and the target nucleic acid sequence. The fabrication approaches, the biosensors architectures, the signal amplification strategies, the detection techniques, and the key performance parameters, such as the linearity range and the limit of detection, were discussed.

Is miR-21 A Therapeutic Target in Cardiovascular Disease?

microRNA-21 (miR-21) serves a multitude of functions at the molecular level through its regulation of messenger RNA. Previous research has sparked interest in the role of miR-21 as a potential therapeutic target in cardiovascular diseases. miR-21 expression contributes to the differentiation, proliferation, and maturation of many cell types, such as fibroblasts, endothelial cells, cardiomyocytes, and endothelial progenitor cells. The function of miR-21 depends upon its expression level in the specific cell types and downstream targets, which determine cell fate. Under pathological conditions, the expression level of miR-21 is altered, leading to abnormal gene regulation of downstream signaling and cardiovascular diseases such as hypertension, cardiac hypertrophy and fibrosis, atherosclerosis, and heart failure. Agomirs or antagomirs can be introduced into the respective tissue type to reverse or stop the progression of the disease. Exosomes in the extracellular vesicles, which mediate many cellular events with high biocompatibility, have a high potential of efficiently delivering miR-21 to their targeted cells. The critical role of miR-21 in cardiovascular disease (CVD) is indisputable, but there are controversial reports on the function of miR-21 in the same disease. This discrepancy sparks interest in better understanding the role of miR-21 in different tissues under different stages of various diseases and the mechanism of how miR-21 inhibitors work.