Albumen exosomes alleviate LPS-induced inflammation of intestinal epithelial cells via miR-22/ATM/p53/NF-κB axis

Biological macromolecules identified in albumen were found benefit to intestinal health, whether albumen contains exosomes and function of their cargos in intestinal inflammation remain unknown. This study aimed to investigate characteristics and cargos of albumen exosomes, as well as their potential roles in alleviating inflammation in intestinal epithelial cells. Our results demonstrated that albumen contains exosomes that are cup-shaped morphology vesicles with diameter ranging from 50 to 200 nm. There were 278 miRNAs and 45 proteins with higher expression levels in albumen exosomes, and they were mainly involved in immune responses and programmed cell death pathways, including apoptosis and p53 signaling pathway. LPS induced overexpression of pro-inflammatory cytokines IL-1β and TNF-α and excessive apoptosis, which could be reversed by albumen exosomes. The beneficial effects of exosomes could be mainly attributed to miRNA cargos and their inhibition on inflammatory response signaling pathways (p53 and NF-κB pathways). Mechanically, exosome miR-22 targeted ATM and inhibited p53/NF-κB pathway, alleviating LPS-induced overexpression of Caspase-3 and Bax, and inflammatory response. Collectively, albumen exosomes alleviate inflammation of intestinal epithelial cells via miR-22/ATM/p53/NF-κB axis and these findings may provide theoretical basis to the potential application of albumen exosomes for intestinal inflammation.

Sex-specific regulation of miR-22 and ERα in white adipose tissue of obese dam's female offspring impairs the early postnatal development of functional beige adipocytes in mice

During inguinal adipose tissue (iWAT) ontogenesis, beige adipocytes spontaneously appear between postnatal 10 (P10) and P20 and their ablation impairs iWAT browning capacity in adulthood. Since maternal obesity has deleterious effects on offspring iWAT function, we aimed to investigate its effect in spontaneous iWAT browning in offspring. Female C57BL/6 J mice were fed a control or obesogenic diet six weeks before mating. Male and female offspring were euthanized at P10 and P20 or weaned at P21 and fed chow diet until P60. At P50, mice were treated with saline or CL316,243, a β3-adrenoceptor agonist, for ten days. Maternal obesity induced insulin resistance at P60, and CL316,243 treatment effectively restored insulin sensitivity in male but not female offspring. This discrepancy occurred due to female offspring severe browning impairment. During development, the spontaneous iWAT browning and sympathetic nerve branching at P20 were severely impaired in female obese dam's offspring but occurred normally in males. Additionally, maternal obesity increased miR-22 expression in the iWAT of male and female offspring during development. ERα, a target and regulator of miR-22, was concomitantly upregulated in the male's iWAT. Next, we evaluated miR-22 knockout (KO) offspring at P10 and P20. The miR-22 deficiency does not affect spontaneous iWAT browning in females and, surprisingly, anticipates iWAT browning in males. In conclusion, maternal obesity impairs functional iWAT development in the offspring in a sex-specific way that seems to be driven by miR-22 levels and ERα signaling. This impacts adult browning capacity and glucose homeostasis, especially in female offspring.

SNHG18 controls vascular smooth muscle cell contractile phenotype and neointimal hyperplasia

AIMS

Long non-coding RNA (LncRNA) small nucleolar RNA host gene 18 (SNHG18) has been widely implicated in cancers. However, little is known about its functional involvement in vascular diseases. Herein, we attempted to explore a role for SNHG18 in modulating vascular smooth muscle cell (VSMC) contractile phenotype and injury-induced neointima formation.

METHODS AND RESULTS

Analysis of single cell RNA sequencing and transcriptomic datasets showed decreased levels of SNHG18 in injured and atherosclerotic murine and human arteries, which is positively associated with VSMC contractile genes. SNHG18 was upregulated in VSMCs by TGFβ1 through transcription factors Sp1 and SMAD3. SNHG18 gene gain/loss-of-function studies revealed that VSMC contractile phenotype was positively regulated by SNHG18. Mechanistic studies showed that SNHG18 promotes a contractile VSMC phenotype by up-regulating miR-22-3p. SNHG18 up-regulates miR-22 biogenesis and miR-22-3p production by competitive binding with the A-to-I RNA editing enzyme, adenosine deaminase acting on RNA-2 (ADAR2). Surprisingly, we observed that ADAR2 inhibited miR-22 biogenesis not through increasing A-to-I editing within primary miR-22, but by interfering the binding of microprocessor complex subunit DGCR8 to primary miR-22. Importantly, perivascular SNHG18 overexpression in the injured vessels dramatically up-regulated the expression levels of miR-22-3p and VSMC contractile genes, and prevented injury-induced neointimal hyperplasia. Such modulatory effects were reverted by miR-22-3p inhibition in the injured arteries. Finally, we observed a similar regulator role for SNHG18 in human VSMCs, and a decreased expression level of both SNHG18 and miR-22-3p in diseased human arteries; and we found that the expression level of SNHG18 was positively associated with that of miR-22-3p in both healthy and diseased human arteries.

CONCLUSION

We demonstrate that SNHG18 is a novel regulator in governing VSMC contractile phenotype and preventing injury-induced neointimal hyperplasia. Our findings have important implications for therapeutic targeting snhg18/miR-22-3p signalling in vascular diseases.

Expression of miR-22 profiling in colorectal normal-adenoma-carcinoma sequence

Colorectal cancer (CRC) is the third most common cancer in the world. MiRNA-22 has emerged as a potential candidate with diagnostic significance; however, its expression profile across the normal-adenoma-carcinoma transition in colorectal remains unexplored. In this study, we evaluated serum miRNA-22 levels in patients with varying stages of CRC. The study cohort comprised 49 healthy controls, 50 patients with polyps, 51 individuals with colorectal adenoma (CRA), and 50 cases of CRC, confirmed through proctocolonoscopy and pathological biopsy. Real-time quantitative polymerase chain reaction was employed to validate the significantly differential expression of serum miRNA-22 among different stages of CRC progression. The 2-ΔΔCT method was utilized to assess the relative changes in serum miRNA-22 expression levels. Our results revealed no significant differences in gender, adenoma grade, location, or TNM classification stage in terms of serum miR-22 expression across the four groups. Notably, both the CRC and CRA groups exhibited higher miR-22 expression levels compared to the control group (p = 0.0001, p = 0.0004), with the CRA and CRC groups displaying higher expression levels than the polyp group (p = 0.02, p = 0.043). Ordered multicategorical logistic regression analysis model revealed the utilization of age, gender, smoking status, and miR-22 expression collectively exhibited the highest value for the area under the curve (AUC = 0.748) in the discrimination between individuals CRC and healthy. The independent factor of expression of miR-22 demonstrated the most notable predictive capacity (AUC = 0.753) when distinguishing between CRA and healthy individuals. Furthermore, the independent expression of miR-22 exhibited discernible potential (AUC = 0.654, 0.636) differentiation between polyps and CRA/ CRC. Notably, the factor of age displayed the most substantial discriminatory power (AUC = 0.741) when distinguishing between polyps and healthy individuals. Our findings provide supportive evidence for considering miR-22 as a potential biomarker for CRC early screening. Nonetheless, the molecular mechanisms of miR-22 regulation in colorectal lesions still need to be investigated.

Use of recombinant microRNAs as antimetabolites to inhibit human non-small cell lung cancer

During the development of therapeutic microRNAs (miRNAs or miRs), it is essential to define their pharmacological actions. Rather, miRNA research and therapy mainly use miRNA mimics synthesized in vitro. After experimental screening of unique recombinant miRNAs produced in vivo, three lead antiproliferative miRNAs against human NSCLC cells, miR-22-3p, miR-9-5p, and miR-218-5p, were revealed to target folate metabolism by bioinformatic analyses. Recombinant miR-22-3p, miR-9-5p, and miR-218-5p were shown to regulate key folate metabolic enzymes to inhibit folate metabolism and subsequently alter amino acid metabolome in NSCLC A549 and H1975 cells. Isotope tracing studies further confirmed the disruption of one-carbon transfer from serine to folate metabolites by all three miRNAs, inhibition of glucose uptake by miR-22-3p, and reduction of serine biosynthesis from glucose by miR-9-5p and -218-5p in NSCLC cells. With greater activities to interrupt NSCLC cell respiration, glycolysis, and colony formation than miR-9-5p and -218-5p, recombinant miR-22-3p was effective to reduce tumor growth in two NSCLC patient-derived xenograft mouse models without causing any toxicity. These results establish a common antifolate mechanism and differential actions on glucose uptake and metabolism for three lead anticancer miRNAs as well as antitumor efficacy for miR-22-3p nanomedicine, which shall provide insight into developing antimetabolite RNA therapies.

Plasma hsa-miR-22-3p Might Serve as an Early Predictor of Ventricular Function Recovery after ST-Elevation Acute Myocardial Infarction

Left ventricle remodeling (LVR) after acute myocardial infarction (aMI) leads to impairment of both systolic and diastolic function, a major contributor to heart failure (HF). Despite extensive research, predicting post-aMI LVR and HF is still a challenge. Several circulant microRNAs have been proposed as LVR predictors; however, their clinical value is controversial. Here, we used real-time quantitative polymerase chain reaction (qRT-PCR) to quantify hsa-miR-22-3p (miR-22) plasma levels on the first day of hospital admission of ST-elevation aMI (STEMI) patients. We analyzed miR-22 correlation to the patients' clinical and paraclinical variables and evaluated its ability to discriminate between post-aMI LVR and non-LVR. We show that miR-22 is an excellent aMI discriminator and can distinguish between LVR and non-LVR patients. The discriminative performance of miR-22 significantly improves the predictive power of a multiple logistic regression model based on four continuous variables (baseline ejection fraction and end-diastolic volume, CK-MB, and troponin). Furthermore, we found that diabetes mellitus, hematocrit level, and the number of erythrocytes significantly influence its levels. These data suggest that miR-22 might be used as a predictor of ventricular function recovery in STEMI patients.

HSP90-Dependent Upregulation of EZH2 Promotes Hypoxia/Reoxygenation-Induced Pyroptosis by Inhibiting miR-22 in Endothelial Cells

Objective

Endothelial cell pyroptosis induced by hypoxia/reoxygenation (H/R) plays a key role in the pathogenesis of myocardial infarction (MI). However, the underlying mechanism is not clearly elucidated.

Methods

Human umbilical vein endothelial cells (HUVECs) exposed to H/R acted as in vitro model to investigate the mechanism of H/R-induced endothelial cell pyroptosis. CCK-8 assays were performed to investigate the viability of HUVECs. Calcein-AM/PI staining was carried out to quantify the death of HUVECs. The expression level of miR-22 was measured by RT-qPCR. The protein expression levels of zeste 2 polycomb repressive complex 2 subunit (EZH2), NLRP3, cleaved caspase-1 (c-caspase-1), GSDMD-N and heat shock protein 90 (HSP90) were measured by Western blot. Levels of IL-1β and IL-18 in culture medium were detected by ELISA. The intracellular localization of EZH2 was detected by immunofluorescence staining. Chromatin immunoprecipitation (ChIP) assay was used to detect the enrichment of EZH2 and H3K27me3 in the miR-22 promoter region. The binding between miR-22 and NLRP3 in HUVECs was confirmed by the dual luciferase assay. Reciprocal coimmunoprecipitation was conducted to detect the direct interaction between HSP90 and EZH2.

Results

H/R increased EZH2 expression, and the EZH2 siRNA could inhibit H/R-induced pyroptosis in HUVECs. H/R reduced miR-22 expression, which was reversed by EZH2 siRNA. Silencing of miR-22 by its inhibitor reversed EZH2 siRNA-induced pyroptosis inhibition in H/R-exposed HUVECs. Upregulation of miR-22 by its mimic suppressed EZH2 overexpression-enhanced pyroptosis in H/R-exposed HUVECs. ChIP assay confirmed that EZH2 bound to the miR-22 promoter region and repressed miR-22 expression through H3K27me3. Furthermore, luciferase reporter assay indicated that NLRP3 was a direct target of miR- 22 in HUVECs. Finally, HSP90 siRNA inhibited H/R-induced EZH2 expression, miR-22 downregulation, and pyroptosis in HUVECs.

Conclusion

H/R induces pyroptosis via the HSP90/EZH2/miR-22/NLRP3 signaling axis in endothelial cells.

miR-22-enriched breast cancer cells display repressed glycolytic metabolism, increased glycogen synthesis, and reduced survival in low glucose conditions

BACKGROUND

Breast cancer (BC) is the second leading cause of cancer-related mortality among women. Beyond the established tumourigenic role of genetic mutations, metabolic reprogramming is another key cancer hallmark. Glucose metabolism in particular is known to be prominently altered in tumours, in order to support biomass accumulation and cancer cell survival. The tumor suppressor microRNA (miRNA) miR-22 has been previously associated with a plethora of BC phenotypes such as growth, invasion-metastasis, and regulation of metabolic phenotypes such as lipid and folate metabolism. In this study, we aimed to investigate the role of miR-22 in the regulation of glucose metabolism in BC cells.

METHODS AND RESULTS

Here we examined how miR-22 affects glucose metabolism in the MCF-7 BC cells. We found that over-expression of miR-22 caused a reduced glycolytic rate in these cells. Moreover, the miRNA also rendered MCF-7 cells more sensitive to lower glucose levels. We next unbiasedly screened the transcript levels of 84 genes relevant to glucose metabolism using the Human Glucose RT2 Profiler PCR Array. Interestingly, the strongest effect identified by this screen was the upregulation of genes involved in glycogen synthesis and the repression of gene involved in glycogen catabolism. Examination of publicly available transcriptomic datasets confirmed the correlations between expression of miR-22 and these glycogen metabolism genes in BC cells.

CONCLUSION

This study has generated evidence for a regulatory role of miR-22 in glucose and glycogen metabolism, expanding the involvement of this miRNA in BC metabolic reprogramming.

Long non-coding RNA FABP5P3/miR-22 axis improves TGFβ1-induced fatty acid oxidation deregulation and fibrotic changes in proximal tubular epithelial cells of renal fibrosis

Severe hydronephrosis increases the risk of urinary tract infection and irretrievable renal fibrosis. While TGFβ1-mediated fibrotic changes in proximal tubular epithelial cells and fatty acid oxidation (FAO) deregulation contribute to renal fibrosis and hydronephrosis. Firstly, a few elements were analyzed in this paper, including differentially-expressed long non-coding RNAs (lncRNAs), and miRNAs correlated to CPT1A, RXRA, and NCOA1. This paper investigated TGFβ1 effects on lncRNA FABP5P3, CPT1A, RXRA, and NCOA1 expression and fibrotic changes in HK-2 cells and FABP5P3 overexpression effects on TGFβ1-induced changes. Moreover, this paper predicted and proved that miR-22 binding to lncRNA FABP5P3, 3'UTR of CPT1A, RXRA, and NCOA1 was validated. The dynamic effects of the FABP5P3/miR-22 axis on TGFβ1-induced changes were investigated. A Renal fibrosis model was established in unilateral ureteral obstruction (UUO) mice, and FABP5P3 effects were investigated. Eventually, this paper concluded that TGFβ1 inhibited lncRNA FABP5P3, CPT1A, RXRA, and NCOA1 expression, induced fibrotic changes in HK-2 cells, and induced metabolic reprogramming within HK-2 cells, especially lower FAO. FABP5P3 overexpression partially reversed TGFβ1-induced changes. miR-22 targeted lncRNA FABP5P3, CPT1A, RXRA, and NCOA1. LncRNA FABP5P3 counteracted miR-22 inhibition of CPT1A, NCOA1, and RXRA through competitive binding. TGFβ1 stimulation induced the activation of TGFβ/SMAD and JAG/Notch signaling pathways; Nocth2 knockdown reversed TGFβ1 suppression on lncRNA FABP5P3. FABP5P3 overexpression attenuated renal fibrosis in unilateral ureteral obstruction mice. The LncRNA FABP5P3/miR-22 axis might be a potent target for improving the FAO deregulation and fibrotic changes in proximal TECs under TGFβ1 stimulation.

Expression analysis of circulating miR-22, miR-122, miR-217 and miR-367 as promising biomarkers of acute lymphoblastic leukemia

BACKGROUND

The role of serum-based biomarkers such as microRNAs in cancer diagnosis has been extensively established. This study aimed to determine the expression levels of bioinformatically selected miRNAs and whether they can be used as biomarkers or a new therapeutic target in patients with acute lymphoblastic leukemia (ALL).

MATERIALS AND METHODS

The expression levels of serum miR-22, miR-122, miR-217, and miR-367 in 21 ALL patients and 21 healthy controls were measured using quantitative real-time PCR. The receiver operating characteristic (ROC) curve and the associated area under the curve (AUC) was used to assess candidate miRNAs' diagnostic value as a biomarker.

RESULTS

The results showed that miR-217 was markedly decreased in patients with ALL compared to controls. Moreover, miR-22, miR-122, and miR-367 were found to be upregulated. Furthermore, ROC analysis showed that serum miR-217 and miR-367 could differentiate ALL patients from healthy individuals, while miR-22 has approximate discriminatory power that requires further investigation.

CONCLUSION

These results provide promising preliminary evidence that circulating miR-217 and miR-367 could be considered potent diagnostic biomarkers and therapeutic goals in this disease.

Spatiotemporal Expression and Functional Analysis of miRNA-22 in the Developing Secondary Palate

OBJECTIVE

Normal development of the embryonic orofacial region requires precise spatiotemporal coordination between numerous genes. MicroRNAs represent small, single-stranded, non-coding molecules that regulate gene expression. This study examines the role of microRNA-22 (miR-22) in murine orofacial ontogeny.

METHODS

Spatiotemporal and differential expression of miR-22 (mmu-miR-22-3p) within the developing secondary palate was determined by in situ hybridization and quantitative real-time PCR, respectively. Bioinformatic approaches were used to predict potential mRNA targets of miR-22 and analyze their association with cellular functions indispensable for normal orofacial ontogeny. An in vitro palate organ culture system was used to assess the role of miR-22 in secondary palate development.

RESULTS

There was a progressive increase in miR-22 expression from GD12.5 to GD14.5 in palatal processes. On GD12.5 and GD13.5, miR-22 was expressed in the future oral, nasal, and medial edge epithelia. On GD14.5, miR-22 expression was observed in the residual midline epithelial seam (MES), the nasal epithelium and the mesenchyme, but not in the oral epithelium. Inhibition of miR-22 activity in palate organ cultures resulted in failure of MES removal. Bioinformatic analyses revealed potential mRNA targets of miR-22 that may play significant roles in regulating apoptosis, migration, and/or convergence/extrusion, developmental processes that modulate MES removal during palatogenesis.

CONCLUSIONS

Results from the current study suggest a key role for miR-22 in the removal of the MES during palatogenesis and that miR-22 may represent a potential contributor to the etiology of cleft palate.

An Immunocompetent Environment Unravels the Proto-Oncogenic Role of miR-22

MiR-22 was first identified as a proto-oncogenic microRNA (miRNA) due to its ability to post-transcriptionally suppress the expression of the potent PTEN (Phosphatase And Tensin Homolog) tumor suppressor gene. miR-22 tumorigenic role in cancer was subsequently supported by its ability to positively trigger lipogenesis, anabolic metabolism, and epithelial-mesenchymal transition (EMT) towards the metastatic spread. However, during the following years, the picture was complicated by the identification of targets that support a tumor-suppressive role in certain tissues or cell types. Indeed, many papers have been published where in vitro cellular assays and in vivo immunodeficient or immunosuppressed xenograft models are used. However, here we show that all the studies performed in vivo, in immunocompetent transgenic and knock-out animal models, unanimously support a proto-oncogenic role for miR-22. Since miR-22 is actively secreted from and readily exchanged between normal and tumoral cells, a functional immune dimension at play could well represent the divider that allows reconciling these contradictory findings. In addition to a critical review of this vast literature, here we provide further proof of the oncogenic role of miR-22 through the analysis of its genomic locus vis a vis the genetic landscape of human cancer.

MicroRNA-22 suppresses NLRP3/CASP1 inflammasome pathway-mediated proinflammatory cytokine production by targeting the HIF-1α and NLRP3 in human dental pulp fibroblasts

AIM

To investigate the synergetic regulatory effect of miR-22 on HIF-1α and NLRP3, subsequently regulating the production of the NLRP3/CASP1 inflammasome pathway-mediated proinflammatory cytokines IL-1β and IL-18 in human dental pulp fibroblasts (HDPFs) during the progression of pulpitis.

METHODOLOGY

Fluorescence in situ hybridization (FISH) and immunofluorescence (IF) were performed to determine the localization of miR-22-3p, NLRP3 and HIF-1α in human dental pulp tissues (HDPTs). The miR-22 mimics and inhibitor or plasmid of NLRP3 or HIF-1α were used to upregulate or downregulate miR-22 or NLRP3 or HIF-1α in HDPFs, respectively. Computational prediction via TargetScan 5.1 and a luciferase reporter assay were conducted to confirm target association. The mRNA and protein expression of HIF-1α, NLRP3, caspase-1, IL-1β and IL-18 were determined by qRT-PCR and western blotting, respectively. The release of IL-1β and IL-18 was analysed by ELISA. The significance of the differences between the experimental and control groups was determined by one-way analysis of variance, p < .05 indicated statistical significance.

RESULTS

A decrease in miR-22 and an increase in HIF-1α and NLRP3 in HDPTs occurred during the transformation of reversible pulpitis into irreversible pulpitis compared with that in the healthy pulp tissues (p < .05). In the normal HDPTs, miR-22-3p was extensively expressed in dental pulp cells. HIF-1α and NLRP3 were mainly expressed in the odontoblasts and vascular endothelial cells. Whereas in the inflamed HDPTs, the odontoblast layers were disrupted. HDPFs were positive for miR-22-3p, HIF-1α and NLRP3. Computational prediction via TargetScan 5.1 and luciferase reporter assays confirmed that both NLRP3 and HIF-1α were direct targets of miR-22 in HDPFs. The miR-22 inhibitor further promoted the activation of NLRP3/CASP1 inflammasome pathway induced by ATP plus LPS and hypoxia (p < .05). In contrast, the miR-22 mimic significantly inhibited the NLRP3/CASP1 inflammasome pathway activation induced by ATP plus LPS and hypoxia (p < .05).

CONCLUSION

MiR-22, as a synergetic negative regulator, is involved in controlling the secretion of proinflammatory cytokines mediated by the NLRP3/CASP1 inflammasome pathway by targeting NLRP3 and HIF-1α. These results provide a novel function and mechanism of miR-22-HIF-1α-NLRP3 signalling in the control of proinflammatory cytokine secretion, thus indicating a potential therapeutic strategy for future endodontic treatment.

Palmitic acid inhibits vascular smooth muscle cell switch to synthetic phenotype via upregulation of miR-22 expression

Synthetic phenotype switch of vascular smooth muscle cells (VSMCs) has been shown to play key roles in vascular diseases. Mounting evidence has shown that fatty acid metabolism is highly associated with vascular diseases. However, how fatty acids regulate VSMC phenotype is poorly understood. Hence, the effects of palmitic acid (PA) on VSMC phenotype were determined in this study. The effect of the PA on VSMCs was measured by live/dead and EdU assays, as well as flow cytometry. Migration ability of VSMCs was evaluated using transwell assay. The underlying targets of miR-22 were predicted using bioinformatics online tools, and confirmed by luciferase reporter assay. The RNA and protein expression of certain gene was detected by qRT-PCR or western blot. PA inhibited VSMC switch to synthetic phenotype, as manifested by inhibiting VSMC proliferation, migration, and synthesis. PA upregulated miR-22 in VSMCs, and miR-22 mimics exerted similar effects as PA treatment, inhibiting VSMC switch to synthetic phenotype. Inhibition of miR-22 using miR-22 inhibitor blocked the impacts of PA on VSMC phenotype modulation, suggesting that PA modulated VSMC phenotype through upregulation of miR-22 expression. We found that ecotropic virus integration site 1 protein homolog (EVI1) was the target of miR-22 in regulation of VSMC phenotype. Overexpression of miR-22 or/and PA treatment attenuated the inhibition of EVI1 on switch of VSMCs. These findings suggested that PA inhibits VSMC switch to synthetic phenotype through upregulation of miR-22 thereby inhibiting EVI1, and correcting the dysregulation of miR-22/EVI1 or PA metabolism is a potential treatment to vascular diseases.

The downregulation of miR-22 and miR-372 may contribute to gestational diabetes mellitus through regulating glucose metabolism via the PI3K/AKT/GLUT4 pathway

Background

Identifying effective regulatory mechanisms will be significant for Gestational diabetes mellitus (GDM) diagnosis and treatment.

Methods

The expressions of miR‐22 and miR‐372 in placenta tissues from 75 pregnant women with GDM and 75 matched healthy controls and HRT8/SVneo cells (a model of insulin resistance) were analyzed by qPCR. The expressions of PI3K, AKT, IRS, and GLUT4 in high glucose‐treated HRT8/SVneo cells transfected with miR‐22 or miR‐372 mimics or inhibitors was assessed by Western blot. A luciferase gene reporter assay was employed to verify miRNAs' target genes.

Results

The expressions of miR‐22 and miR‐372 in placental tissues from GDM patients and HRT8/SVneo cells were significantly decreased compared with the respective controls. The GLUT4 expression was significantly decreased in the placenta tissues of GDM and HRT8/SVneo cells with high glucose transfected with miR‐22 and miR‐372 inhibitors. We confirmed that SLC2A4, the gene encoding GLUT4, was a direct target of miR‐22 and miR‐372. In this study, we report that the lower expressions of miR‐22 and miR‐372 in placental tissue from GDM patients.

Conclusion

Our results further suggested that the downregulations of miR‐22 and miR‐372 may contribute to GDM through regulating the PI3K/GLUT4 pathway.

Suppression of endothelial miR-22 mediates non-small cell lung cancer cell-induced angiogenesis

MicroRNAs (miRNAs) expressed in endothelial cells (ECs) are powerful regulators of angiogenesis, which is essential for tumor growth and metastasis. Here, we demonstrated that miR-22 is preferentially and highly expressed in ECs, while its endothelial level is significantly downregulated in human non-small cell lung cancer (NSCLC) tissues when compared to matched nontumor lung tissues. This reduction of endothelial miR-22 is possibly induced by NSCLC cell-secreted interleukin-1β and subsequently activated transcription factor nuclear factor-κB. Endothelial miR-22 functions as a potent angiogenesis inhibitor that inhibits all of the key angiogenic activities of ECs and consequently NSCLC growth through directly targeting sirtuin 1 and fibroblast growth factor receptor 1 in ECs, leading to inactivation of AKT/mammalian target of rapamycin signaling. These findings provide insight into the molecular mechanisms of NSCLC angiogenesis and indicate that endothelial miR-22 represents a potential target for the future antiangiogenic treatment of NSCLC.

MicroRNA-22 inhibition promotes the development of atherosclerosis via targeting interferon regulator factor 5

Atherosclerosis is generally accepted as a chronic inflammatory disease and is the most important pathological process underlying the cardiovascular diseases. MiR-22 exerts an important role in tumorgenesis, obesity and NAFLD development, as well as cardiovascular diseases. However, a certain role of miR-22 in the pathogenesis of atherosclerosis remains undetermined. Here, we showed that miR-22 exhibited a negative association with the deteriorated atherosclerotic plaque and showed significant downregulated expression in macrophages. Next, treatment of ApoE deficiency (ApoE^-/-) mice with miR-22 inhibitors which were then subjected to high fat diet (HFD) for 12 weeks were performed to investigate the function of miR-22 on atherogenesis. The results exhibited that miR-22 inhibition dramatically promoted atherosclerotic plaques but attenuated plaque stabilization which were accompanied by decreased smooth muscle cell and collagen content, but increased macrophage infiltration and lipid accumulation. More importantly, the in vivo and in vitro experiments suggested that miR-22 inhibition accelerated inflammatory response and foam cell formation. Mechanistically, we demonstrated interferon regulator factor 5 (IRF5) was an important target of miR-22 and it was required for the regulation of inflammation mediated by miR-22 inhibition. Collectively, these evidences revealed that miR-22 inhibition promoted the atherosclerosis progression through activation of IRF5.

Lipoxin A4 methyl ester protects PC12 cells from ketamine-induced neurotoxicity via the miR-22/BAG5 pathway

OBJECTIVE

Ketamine is an anesthetic that induces neurotoxicity when administered at high doses. In this work, we explored the protective effects of lipoxin A₄ methyl ester (LXA₄ ME) against ketamine-induced neurotoxicity and the underlying protective mechanism in pheochromocytoma (PC12) cells.

METHODS

PC12 cells were treated with 50 μM of ketamine and different LXA₄ ME concentrations of LXA4 ME (5-50 nM) for 24 h, and their viability, apoptosis, and oxidative status were assessed.

RESULTS

Quantitative real-time polymerase chain reaction experiments showed that ketamine downregulated miR-22 expression and upregulated Bcl-2-associated athanogene 5 (BAG5) in PC12 cells in a concentration-dependent manner. LXA₄ ME induced the opposite effects, thus attenuating ketamine-induced neurotoxicity. Further in vitro assays showed that miR-22 directly targeted BAG5, thus promoting cell viability by suppressing cell apoptosis and oxidative stress. Under expression miR-22 or upregulation of BAG5 antagonized the effects of LXA₄ ME.

CONCLUSION

LXA₄ ME can protect PC12 cells from ketamine-induced neurotoxicity by activating the miR-22/BAG5 signaling pathway. Thus, LXA₄ ME can be used as a protective drug against ketamine-induced neural damage.

miR-22 Modulates Lenalidomide Activity by Counteracting MYC Addiction in Multiple Myeloma

Simple Summary

MYC-driven deregulation of microRNAs represents a critical event in human malignancies, including multiple myeloma (MM). Although the introduction of new therapeutic strategies has prolonged survival of patients, MM remains an incurable disease, often due to the onset of drug resistance. MYC hyperactivation is involved in the development of resistance to immunomodulatory imide drugs (IMiDs), but the mechanism is still unclear. Here, we report that MYC represses the transcription of tumor suppressor miR-22 in MM, and that low miR-22 expression is associated with IMiD resistance in MM patients. By in silico and in vitro analysis, we show that miR-22 mimics affect MYC signaling, leading to MM cell death in MYC proficient cells. Furthermore, we demonstrate here that lenalidomide treatment enhances miR-22 activity by reducing the MYC inhibitory effect, and that the combination of lenalidomide with miR-22 mimics restores drug sensitivity, leading to synergistic anti-MM activity.

Abstract

Background: MYC is a master regulator of multiple myeloma (MM) by orchestrating several pro-tumoral pathways, including reprograming of the miRNA transcriptome. MYC is also involved in the acquirement of resistance to anti-MM drugs, including immunomodulatory imide drugs (IMiDs). Methods: In silico analysis was performed on MM proprietary and on public MMRF-CoMMpass datasets. Western blot and chromatin immunoprecipitation (ChIP) experiments were performed to validate miR-22 repression induced by MYC. Cell viability and apoptosis assays were used to evaluate lenalidomide sensitization after miR-22 overexpression. Results: We found an inverse correlation between MYC and miR-22 expression, which is associated with poor outcome in IMiD-treated MM patients. Mechanistically, we showed that MYC represses transcription of miR-22, which, in turn, targets MYC, thus establishing a feed-forward loop. Interestingly, we found that IMiD lenalidomide increases miR-22 expression by reducing MYC repression and, most importantly, that the combination of lenalidomide with miR-22 mimics results in a synergistic direct and NK-mediated cytotoxic activity. Conclusions: Taken together, our findings indicate that: (1) low miR-22 expression could represent a potential predictive biomarker of poor lenalidomide response in MM patients; and (2) miR-22 reduces MYC oncogenic activity, thus triggering a novel synthetic lethality loop, which sensitizes MM cells to lenalidomide.

TET2 Mutation and High miR-22 Expression as Biomarkers to Predict Clinical Outcome in Myelodysplastic Syndrome Patients Treated with Hypomethylating Therapy

Tet methylcytosine dioxygenase 2 (TET2) is one of the most frequently mutated genes in myelodysplastic syndrome (MDS). TET2 is known to involve a demethylation process, and the loss of TET2 is thought to cause DNA hypermethylation. Loss of TET2 function is known to be caused by genetic mutations and miRNA, such as miR-22. We analyzed 41 MDS patients receiving hypomethylating therapy (HMT) to assess whether TET2 mutation status and miR-22 expression status were associated with their clinical characteristics and treatment outcomes. Responsiveness to HMT was not affected by both TET2 mutation (odds ratio (OR) 0.900, p = 0.909) and high miR-22 expression (OR 1.548, p = 0.631). There was a tendency for TET2 mutation to be associated with lower-risk disease based on IPSS (Gamma = -0.674, p = 0.073), lower leukemic transformation (OR 0.170, p = 0.040) and longer survival (Hazard ratio 0.354, p = 0.059). Although high miR-22 expression also showed a similar tendency, this tendency was weaker than that of TET2 mutation. In summary, the loss of TET2 function, including both TET2 mutation and high miR-22 expression, was not a good biomarker for predicting the response to HMT but may be associated with lower-risk disease based on IPSS, lower leukemic transformation and longer survival.

MiR-22, a serum predictor of poor outcome and therapy response in diffuse large B-cell lymphoma patients

Diffuse large B-cell lymphoma (DLBCL) is an aggressive, heterogeneous neoplasm where prognostication and therapeutic decision are challenging. The available prognostic tools are not able to identify all patients refractory to treatment. MicroRNAs, small RNAs frequently deregulated in cancer, stably circulate in biofluids, representing interesting candidates for non-invasive biomarkers. Here we validated serum miR-22, an evolutionarily conserved microRNA, as a prognostic/predictive biomarker in DLBCL. Moreover, we found that its expression and release from DLBCL cells are related to therapy response and adversely affect cell proliferation. These results suggest that miR-22 is a promising complementary or even independent non-invasive biomarker for DLBCL management.

LncRNA-HOTAIR promotes endothelial cell pyroptosis by regulating the miR-22/NLRP3 axis in hyperuricaemia

Long non‐coding RNA (lncRNA) plays an important role in the renal inflammatory response caused by hyperuricaemia. However, the underlying molecular mechanisms through which lncRNA is involved in endothelial injury induced by hyperuricaemia remain unclear. In this study, we investigated the regulatory role of lncRNA‐HOTAIR in high concentration of uric acid (HUA)–induced renal injury. We established hyperuricaemia mouse model and an in vitro uric acid (UA)–induced human umbilical vein endothelial cell (HUVEC) injury model. In HUA‐treated HUVECs and hyperuricaemia mice, we observed increased HOTAIR and decreased miR‐22 expression. The expression of pyroptosis‐associated protein (NLRP3, Caspase‐1, GSDMD‐N, GSDMD‐FL) was increased. The release of LDH, IL‐1β and IL‐18 in cell supernatants and the sera of model mice was also increased. The proliferation of HUVECs stimulated by HUA was significantly inhibited, and the number of TUNEL‐positive cells in hyperuricaemia mouse kidney was increased. Bioinformatics analysis and luciferase reporter and RIP assays confirmed that HOTAIR promoted NLRP3 inflammasome activation by competitively binding miR‐22. In gain‐ or loss‐of‐function experiments, we found that HOTAIR and NLRP3 overexpression or miR‐22 knock down activated the NLRP3 inflammasome and promoted pyroptosis in HUA‐treated HUVECs, while NLRP3 and HOTAIR knockdown or a miR‐22 mimic exerted the opposite effects. Furthermore, in vivo experiments validated that HOTAIR knockdown alleviated renal inflammation in hyperuricaemia mice. In conclusion, we demonstrated that in hyperuricaemia, lncRNA‐HOTAIR promotes endothelial cell pyroptosis by competitively binding miR‐22 to regulate NLRP3 expression.

MiR-22 regulated T cell differentiation and hepatocellular carcinoma growth by directly targeting Jarid2

MiR-22 has been demonstrated to inhibits tumor growth in several cancers. However, its function in the tumor microenvironment is still unclear, especially for T cell differentiation. Here, miR-22 expression in the circulating T cells from hepatocellular carcinoma (HCC) patients and healthy controls was analyzed with quantitative polymerase chain reaction (qPCR). Diethylnitrosamine (DEN)/phenobarbital (PB)-mediated primary HCC and Hepa1-6 subcutaneous tumor mouse models were established and subjected to lenti-miR-22 injection. Mice immunoreconstituted with miR-22-overexpressing T cells were employed to investigate the antitumor effect of miR-22 in mice. Luciferase assay, immunofluorescent staining, in vitro Th17 cell differentiation assay, and rescue experiments were employed to investigate the mechanism underlying the miR-22-mediated regulation of Th17 cell differentiation and liver tumor growth. Results confirmed the dramatic downregulation of miR-22 expression in malignant tissues and circulating T cells from patients with HCC. MiR-22 expression correlated with good prognosis of patients. Overexpression of miR-22 impaired the DEN/PB-induced primary HCC formation and the growth of Hepa1-6 subcutaneous tumors by promoting Th17 differentiation. Injection of miR-22-overexpressing T cells in irradiated mice resulted in the inhibition of Hepa1-6 subcutaneous tumor growth via Th17 differentiation promotion. MiR-22 could directly bind to Jarid2, which played an important role during the miR-22-mediated regulation of Th17 differentiation. Taken together, our study expands the understanding of miR-22 function and provides a therapy target for HCC.

MicroRNA-22 in female malignancies: Focusing on breast, cervical, and ovarian cancers

MicroRNAs (miRNAs), a novelty-defined class of regulatory genes, have revolutionized principles of classical bimolecular. These RNAs regulate the expression of a gene through inhibition of translational initiation or targeting mRNAs for degradation. MiRNAs act in several biological operations, including proliferation, differentiation, and cell death, and their expression is often abnormal in human diseases such as cancer. In recent years, miR-22 has attracted much attention from researchers. Its expression is downregulated in female malignancies such as breast, cervical, and ovarian cancers, exhibiting that miR-22 plays a tumor-suppressive function in these cancers. Also, different reports exist about the involvement of miR-22 in non-tumor diseases. In the present review, we report the results of performed studies on the potential roles of miR-22 in female malignancies with a focus on breast, cervical, and ovarian cancers. Also, we summary its predicted target genes in various cancers. In conclusion, it is effective for researchers to understand the role of miR-22 in different cellular operations.

MiR-22 Inhibition Alleviates Cardiac Dysfunction in Doxorubicin-Induced Cardiomyopathy by Targeting the sirt1/PGC-1α Pathway

Doxorubicin (DOX) cardiotoxicity is a life-threatening side effect that leads to a poor prognosis in patients receiving chemotherapy. We investigated the role of miR-22 in doxorubicin-induced cardiomyopathy and the underlying mechanism in vivo and in vitro. Specifically, we designed loss-of-function and gain-of-function experiments to identify the role of miR-22 in doxorubicin-induced cardiomyopathy. Our data suggested that inhibiting miR-22 alleviated cardiac fibrosis and cardiac dysfunction induced by doxorubicin. In addition, inhibiting miR-22 mitigated mitochondrial dysfunction through the sirt1/PGC-1α pathway. Knocking out miR-22 enhanced mitochondrial biogenesis, as evidenced by increased PGC-1α, TFAM, and NRF-1 expression in vivo. Furthermore, knocking out miR-22 rescued mitophagy, which was confirmed by increased expression of PINK1 and parkin and by the colocalization of LC3 and mitochondria. These protective effects were abolished by overexpressing miR-22. In conclusion, miR-22 may represent a new target to alleviate cardiac dysfunction in doxorubicin-induced cardiomyopathy and improve prognosis in patients receiving chemotherapy.

Inhibiting miR-22 Alleviates Cardiac Dysfunction by Regulating Sirt1 in Septic Cardiomyopathy

High morbidity and mortality are the most typical characteristics of septic cardiomyopathy. We aimed to reveal the role of miR-22 in septic cardiomyopathy and to explore the underlying mechanisms. miR-22 cardiac-specific knockout (miR-22^cKO) mice and miR-22 cardiac-specific transgenic (miR-22^cOE) mice were subjected to a cecal ligation and puncture (CLP) operation, while a sham operation was used in the control group. The echocardiogram results suggested that miR-22^cKO CLP mice cardiac dysfunction was alleviated. The serum LDH and CK-MB were reduced in the miR-22^cKO CLP mice. As expected, there was reduced apoptosis, increased autophagy and alleviated mitochondrial dysfunction in the miR-22^cKO CLP mice, while it had contrary role in the miR-22^cOE group. Inhibiting miR-22 promoted autophagy by increasing the LC3II/GAPDH ratio and decreasing the p62 level. Additionally, culturing primary cardiomyocytes with lipopolysaccharide (LPS) simulated sepsis-induced cardiomyopathy in vitro. Inhibiting miR-22 promoted autophagic flux confirmed by an increased LC3II/GAPDH ratio and reduced p62 protein level under bafilomycin A1 conditions. Knocking out miR-22 may exert a cardioprotective effect on sepsis by increasing autophagy and decreasing apoptosis via sirt1. Our results revealed that targeting miR-22 may become a new strategy for septic cardiomyopathy treatment.

LncRNA NBR2 aggravates hepatoblastoma cell malignancy and promotes cell proliferation under glucose starvation through the miR-22/TCF7 axis

Hepatoblastoma (HB) is the most commonly seen pediatric liver malignancy. With frequent mutations in CTNNB1 gene that encodes β-catenin, hepatoblastoma has been considered as a Wnt/β-catenin-activated malignant tumor. Altered glucose metabolism upon nutrient deprivation (glucose starvation) might also be a critical event in hepatoblastoma carcinogenesis. The present study provides a lncRNA NBR2/miR-22/TCF7 axis modulating proliferation, invasion, migration, and apoptosis of hepatoblastoma cells upon glucose starvation through Wnt and downstream TCF7 signaling pathways. The expression of NBR2 is significantly increased within hepatoblastoma tissue samples; moreover, under incubation with 0 mM glucose (glucose starvation), NBR2 expression is significantly upregulated. NBR2 silencing not only inhibited hepatoblastoma cell viability, invasion, and migration under normal culture condition but also promoted the cell apoptosis under glucose starvation. NBR2 silencing in hepatoblastoma cells also decreased TCF7 mRNA expression and TCF7 protein levels, as well as the protein levels of the cell cycle, glucose entrapment, and EMT markers. miR-22 is directly bound to both NBR2 and TCF7; lncRNA NBR2 counteracted miR-22-mediated repression on TCF7 via acting as a ceRNA. The effects of NBR2 silencing on TCF7 expression, hepatoblastoma cell phenotype, and cell cycle, glucose entrapment, and EMT markers were all significantly reversed by miR-22 inhibition. In conclusion, lncRNA NBR2 aggravates hepatoblastoma cell malignancy through competing with TCF7 for miR-22 binding, therefore counteracting miR-22-mediated repression on TCF7. LncRNA NBR2 might be a promising target to inhibit hepatoblastoma cell proliferation under glucose starvation.

Twist activates miR-22 to suppress estrogen receptor alpha in breast cancer

TWIST1 (Twist) is a basic helix-loop-helix transcription factor that is overexpressed in many cancers and promotes tumor cell invasion, metastasis, and recurrence. In this study, we demonstrate that Twist upregulates expression of microRNA 22 (miR-22) which, in turn, downregulates estrogen receptor alpha (ER) expression in breast cancer. Initial analysis of miR-22 and Twist expression in a panel of breast cancer cell lines showed a direct correlation between Twist and miR-22 levels with miR-22 being highly expressed in ER negative cell lines. Overexpressing Twist caused increased miR-22 levels while downregulating it led to decreased miR-22 expression. To characterize the upstream promoter region of miR-22, we utilized rapid amplification of cDNA ends and identified the transcription start site and the putative promoter region of miR-22. Mechanistically, we determined that Twist, in combination with HDAC1 and DNMT3B, transcriptionally upregulates miR-22 expression by binding to E-boxes in the proximal miR-22 promoter. We also established that miR-22 causes an increase in growth in 3D but not 2D cultures. Importantly, we observed a direct correlation between increased breast cancer grade and Twist and miR-22 expression. We also identified two potential miR-22 binding sites in the 3'-UTR region of ER and confirmed by promoter assays that miR-22 regulates ER expression by binding to both target sites. These results reveal a novel pathway of ER suppression by Twist through miR-22 activation that could potentially promote the ER negative phenotype in breast cancers.

MiR-22 modulates brown adipocyte thermogenesis by synergistically activating the glycolytic and mTORC1 signaling pathways

Background: Brown adipose tissue (BAT) dissipates chemical energy as heat and has the potential to be a protective strategy to prevent obesity. microRNAs (miRNAs) are emerging as important posttranscriptional factors affecting the thermogenic function of BAT. However, the regulatory mechanism underlying miRNA-mediated energy metabolism in BAT is not fully understood. Here, we explored the roles of miR-22 in BAT thermogenesis and energy metabolism.

Methods: Using global and conditional knockout mice as in vivo models and primary brown adipocytes as an in vitro system, we investigated the function of miR-22 in BAT thermogenesis in vivo and in vitro.

Results: miR-22 expression was upregulated in BAT in response to cold exposure and during brown preadipocyte differentiation. Both global and conditional knockout mice displayed BAT whitening, impaired cold tolerance, and decreased BAT thermogenesis. Moreover, we found that miR-22 deficiency impaired BAT glycolytic capacity, which is critical for thermogenesis. The mechanistic results revealed that miR-22 activated the mTORC1 signaling pathway by directly suppressing Tsc1 and concomitantly directly suppressing Hif1an, an inhibitor of Hif1α, which promotes glycolysis and maintains thermogenesis.

Conclusions: Our findings identify miR-22 as a critical regulator in the control of thermogenesis in BAT and as a potential therapeutic target for human metabolic disorders.

ncRNA therapy with miRNA-22-3p suppresses the growth of triple-negative breast cancer

Deregulation of noncoding RNAs, including microRNAs (miRs), is implicated in the pathogenesis of many human cancers, including breast cancer. Through extensive analysis of The Cancer Genome Atlas, we found that expression of miR-22-3p is markedly lower in triple-negative breast cancer (TNBC) than in normal breast tissue. The restoration of miR-22-3p expression led to significant inhibition of TNBC cell proliferation, colony formation, migration, and invasion. We demonstrated that miR-22-3p reduces eukaryotic elongation factor 2 kinase (eEF2K) expression by directly binding to the 3' untranslated region of eEF2K mRNA. Inhibition of EF2K expression recapitulated the effects of miR-22-3p on TNBC cell proliferation, motility, invasion, and suppression of phosphatidylinositol 3-kinase/Akt and Src signaling. Systemic administration of miR-22-3p in single-lipid nanoparticles significantly suppressed tumor growth in orthotopic MDA-MB-231 and MDA-MB-436 TNBC models. Evaluation of the tumor response, following miR-22-3p therapy in these models using a novel mathematical model factoring in various in vivo parameters, demonstrated that the therapy is highly effective against TNBC. These findings suggest that miR-22-3p functions as a tumor suppressor by targeting clinically significant oncogenic pathways and that miR-22-3p loss contributes to TNBC growth and progression. The restoration of miR-22-3p expression is a potential novel noncoding RNA-based therapy for TNBC.

Circ-ITCH restrains the expression of MMP-2, MMP-9 and TNF-α in diabetic retinopathy by inhibiting miR-22

Diabetic retinopathy (DR), the most frequent complication of diabetes mellitus, is the principal cause of acquired blindness worldwide. Although the roles of circRNAs have been extensively explored, the detailed physiological and pathological functions of circRNAs in DR are less understood. Here, we studied the biological effects of circ-ITCH in diabetic retinal pigment epithelial cells (RPEs) and explored the underlying mechanisms. As our results shown, the RNA expression of circ-ITCH was significantly lower in RPEs isolated from diabetic rats than they were in those isolated from normal rats. While diabetes induced an increase in MMP-2, MMP-9 and TNF-α in RPEs, circ-ITCH overexpression exerted an inhibitory on these increases and knockdown of circ-ITCH reversed the inhibitory. In addition, increased expression of miR-22 in RPEs correlated with diabetes and downregulation of circ-ITCH. Remarkably, in the presence of miR-22 mimics, the effects of circ-ITCH on the MMP-2 and MMP-9 were both antagonized. Collectively, our data supports a cellular signaling cascade in which circ-ITCH-inhibited miR-22 activity modulates the expression of MMP-2, MMP-9 and TNF-α in DR.

Curcumin inhibits proliferation, migration and neointimal formation of vascular smooth muscle via activating miR-22

Context: Curcumin has antitumor, antioxidative, anti-inflammatory, and anti-proliferative properties.Objective: To investigate the role of miR-22 during curcumin-induced changes in vascular smooth muscle cells (VSMC) and neointima formation in balloon-injured rat abdominal aorta.Materials and methods: Sprague-Dawley rats were randomised to the sham-operated (n = 10), operated control (injured, n = 10), and curcumin treatment (n = 10) groups. miR-22 expression was determined by real-time PCR. SP1 was assessed by western blot and real-time PCR. Rat aortic smooth muscle A7r5 cells were used to determine VSMC proliferation and migration, which were measured by the MTS, EdU staining, Transwell, and wound healing assays.Results: miR-22 levels declined following arterial balloon injury in vivo (48% at 3d, p < 0.05) and serum stimulation in vitro (45% at 24 h, p < 0.01). Functional studies revealed that miR-22 negatively regulated the proliferation and migration of VSMCs by directly targeting the SP1 transcription factor in VSMCs. Curcumin increased the expression of miR-22 (81%, p < 0.05) and decreased the protein expression of SP1 in VSMCs (25%, p < 0.05). miR-22 inhibition was found to attenuate the effects of curcumin on VSMC functions. Curcumin increased miR-22 (46%, p < 0.01), decreased the SP1 protein (19%, p < 0.05), and inhibited vascular neointimal area (48%, p < 0.01) in vivo.Discussion: The miR-22/SP1 pathway is involved in the protective role of curcumin during arterial balloon injury, but the mechanisms remain unclear.Conclusion: miR-22 is involved in the inhibitory effects of curcumin on VSMCs' proliferation, migration and neointima hyperplasia after arterial balloon injury in rats. Curcumin could be used to prevent neointimal hyperplasia after angioplasty.

MiR-22 modulates the expression of lipogenesis-related genes and promotes hepatic steatosis in vitro

Nonalcoholic fatty liver disease (NAFLD) is highly correlated with obesity, and lifestyle changes to reduce weight remain the main therapeutic approach. The noncoding RNA miR-22 has previously been reported to be highly abundant in the sera of NAFLD patients. In addition, miR-22 directly targets peroxisome proliferative-activated receptor, Pgc-1α, peroxisome proliferator-activated receptor α, and sirtuin 1 (Sirt1), which are important factors involved in fatty acid metabolism. Given that miR-22 directly targets genes involved in the control of metabolism and obesity, we investigated whether miR-22 contributes to metabolic alterations induced by obesity. We observed increased expression of miR-22, decreased expression of Sirt1, and alterations in the expression of adipogenesis-related genes in a mouse model of obesity and a human hepatocyte cell line. We identified that miR-22 and the 3'-UTR of Sirt1 are complementary. Mutation of the complementary fragment abolishes the ability of miR-22 to regulate the Sirt1 gene. Furthermore, treatment of hepatic steatosis cells with miR-22 mimics or inhibitors showed that miR-22 can promote hepatic steatosis, and miR-22 inhibitors effectively reduced triglyceride levels without affecting cell activity. Finally, we validated that miR-22 has similar effects on downstream lipid metabolism-related genes. Our data reveal the pathways and mechanisms through which miR-22 regulates lipid metabolism and suggest that miR-22 inhibitors may have potential as candidate drugs for NAFLD and obesity.

Circular RNA cZNF292 silence alleviates OGD/R-induced injury through up-regulation of miR-22 in rat neural stem cells (NSCs)

Background: Hypoxic-ischaemic encephalopathy (HIE) is a prevailing severe brain damage disease in newborns, and caused by perinatal asphyxia cerebral ischaemia and reperfusion. Here, we investigated the role of cZNF292 in oxygen-glucose deprivation/reperfusion (OGD/R)-induced neural stem cells (NSCs) injury, and explored the underlying molecular mechanism.Methods: Before NSCs were subjected to OGD/R treatment, NSCs were transfected with or without overexpressing cZNF292, si-cZNF292 or miR-22 inhibitor. Viability, apoptosis and potential molecular mechanism were examined. Cell viability and apoptotic rate were evaluated utilizing cell counting kit-8 (CCK-8) and flow cytometry. The cZNF292 and miR-22 expression was determined utilizing quantitative reverse transcription-PCR (qRT-PCR). Moreover, apoptosis and Wnt/β-catenin and PKC/ERK pathways-associated proteins were quantified applying western blot.Results: OGD/R repressed viability and promoted apoptosis of NSCs. Also, cZNF292 expression was promoted by OGD/R treatment. Moreover, cZNF292 overexpression further caused OGD/R-stimulated damage. Inversely, silencing cZNF292 alleviated OGD/R-stimulated damage in NSCs. In addition, miR-22 expression was negatively regulated by cZNF292. It was confirmed that silencing cZNF292 attenuated OGD/R-induced NSCs injury and promoted the activation of Wnt/β-catenin and PKC/ERK pathways via the up-regulation of miR-22.Conclusions: The cZNF292 silence alleviated OGD/R-induced injury through the up-regulation of miR-22 in NSCs, and which furnished the theoretical basis for further research on HIE progression.

The therapeutic potential of exosomal miR-22 for cervical cancer radiotherapy

Cervical cancer is the fourth-most prevalent malignancy in women. For advanced cervical cancer, radiotherapy is a major treatment. Micro RNAs (miRNAs) are small, noncoding RNAs that negatively regulate the target gene expression posttranscriptionally. miR-22 is frequently downregulated in various cancers including cervical cancer, and is associated with a poor prognosis in cervical cancer. Exosomes are small endosomally secreted vesicles that carry components such as proteins, messenger RNA (mRNA), DNA and miRNA. We investigated whether or not exosomes can efficiently deliver miR-22 to recipient cervical cancer cells and affect the gene expression in the cells, as well as assessed the role of exosomal miR-22 in radiosensitivity. Exosomes containing high levels of miR-22 were extracted by ultracentrifugation and then characterized by Western blotting, a nanoparticle tracking analysis and electron microscopy. The high presence of miR-22 in the exosome was confirmed by real-time polymerase chain reaction. After the administration of the collected exosomal miR-22 to SKG-II and C4-I cervical cancer cells, the level of miR-22 in the cells was significantly increased, indicating the absorption of the exosomal miR-22. When miR-22 encapsulated in exosomes was administered to the SKG-II cells, the level of c-Myc binding protein (MYCBP) and human telomerase reverse transcriptase (hTERT) was significantly decreased in correlation with increased radiosensitivity determined by a clonogenic assay. Taken together, these results suggest that the administration of exosomal miR-22 may be a novel drug delivery system for cervical cancer radiotherapy.

Rs145204276 and rs4759314 affect the prognosis of prostate cancer by modulating the GAS5/miR-1284/HMGB1 and HOTAIR/miR-22/HMGB1 signalling pathways

Non-coding RNAs play an important role in the pathogenesis of prostate cancer (PC). This study aims to characterize the role of GAS5 rs145204276 and HOTAIR rs4759314 polymorphisms in the pathogenesis of PC. Both INS allele of GAS5 rs145204276 and A allele of HOTAIR rs4759314 were identified to increase the survival of PC patients. And patients carrying DEL/DEL + AG genotypes tend to present higher levels of HMGB1, GAS5, HOTAIR and lower levels of miR-1284 and miR-22. In addition, the transcription activity of GAS5 promoter was increased by the deletion allele of rs145204276 polymorphism, while the G allele of rs4759314 polymorphism increased the transcription activity of HOTAIR promoter. GAS5 and HOTAIR could bind to miR-1284 and miR-22, respectively, while miR-1284 and miR-22 could bind to the 3'UTR of HMGB1. Compared with the control group, the expressions of miR-1284 or miR-22 were decreased with the presence of GAS5 or HOTAIR, and the expression of HMGB1 was the highest in the GAS5 + HOTAIR group. In summary, the findings of this study demonstrated that both GAS5 rs145204276 and HOTAIR rs4759314 polymorphisms could affect the prognosis of PC by modulating the expression of HMGB1 via modulating the GAS5/miR-1284/HMGB1 and HOTAIR/miR-22/HMGB1 signalling pathways.

MicroRNA Expression Levels in Patients with Hashimoto Thyroiditis: A Single Centre Study

OBJECTIVE

To determine the circulatory miRNA expression levels in patients with Hashimoto thyroiditis (HT) at the time of diagnosis and follow-up period compared with healthy controls.

METHODS

We collected blood samples from 34 patients with HT (4 males and 30 females) at the time of first diagnosis (Group P) and euthyroid period (Group E). Thirty-three healthy controls (Group H) blood samples were also included in the study. Expression levels of five different circulating miRNAs (miR-22, miR-141, miR-155, miR-375, miR-451) were evaluated using real-time polymerase chain reaction.

RESULTS

There was a significant difference in miR-375 levels between the groups P and H. Also, for miR-451, there was a significant difference between the P and E groups. Finally, there was a moderate positive correlation between thyroid-stimulating hormone values and miR-22 expression levels for the P group.

CONCLUSION

miRNAs have important roles at all stages of the diseases. More studies must be performed in all thyroid diseases and autoimmune diseases, including HT.

MicroRNA-22 Inhibits the Apoptosis of Vascular Smooth Muscle Cell by Targeting p38MAPKα in Vascular Remodeling of Aortic Dissection

MicroRNA 22 (miR-22) was found in diverse cardiovascular diseases to have a role in regulating multiple cellular processes. However, the regulatory role of miR-22 in aortic dissection (AD) was still unclear. The miR-22 expression in human aorta was explored. A series of mimic, inhibitor, or small interfering RNA (siRNA) plasmids were delivered into vascular smooth muscle cells (VSMCs) to explore the effects of miR-22 and p38 mitogen-activated protein kinase α (p38MAPKα) in controlling VSMC apoptosis in vitro. In addition, a mouse AD model was established, and histopathologic analyses were performed to evaluate the regulatory effects of miR-22. Reduced miR-22 and increased apoptosis of VSMCs was seen in human AD aorta. Downregulation of miR-22 increased the apoptosis of VSMCs in vitro. Bioinformatics analyses revealed that p38MAPKα was a target of miR-22. Inhibiting p38MAPKα expression could reverse the apoptosis of VSMCs induced by miR-22 downregulation. Knockdown of miR-22 in the AD mouse model significantly promoted the development of AD. Our data underscore the importance of vascular remodeling and VSMC function in AD. miR-22 may represent a new therapeutic approach for AD by regulating the apoptosis of VSMCs through the MAPK signaling pathway.

Lipid nanoparticles co-loaded with miRNA-22 and methotrexate for enhanced anti-inflammatory response in rheumatoid arthritis

Present investigation was aimed at developing methotrexate (MTX) and miR-22 mimics-loaded lipid nanoparticles for the effective treatment of rheumatoid arthritis. The dual therapeutics loaded nanoparticles was prepared and subjected to in vitro and in vivo characterizations. The in vivo study was performed on adjuvant- induced arthritis model. The addition of IL-1β significantly decreased the expression of miR-22 levels in negative control groups, whereas miR-22 mimics treated cells showed significantly higher miR-22 expression compared to both the NC groups. MTX+miR-22 showed significantly lower cell viability compared to that of free MTX indicating a synergistic anti-inflammatory in the MH7A cells. To be specific, MTX/miR-22-loaded lipid nanoparticles (MTmiR-NP) showed the significantly lower cell viability compared to any other group indicating the potential of lipid nanoparticles. Consistently, MTmiR-NP exhibited a significantly higher cell apoptosis (~50%) compared to any other tested group further reiterating the nanoparticle-based combinational therapeutics. MTmiR-NP exhibited the significant reduction in the paw thickness and significantly lower arthritic score compared to all other groups on all time points. Present study clearly highlights the potential of lipid nanoparticles-based synergistic combination of MTX and miR-22 in achieving higher therapeutic response in rheumatoid arthritis treatment.

miR-22 Suppresses Tumor Invasion and Metastasis in Colorectal Cancer by Targeting NLRP3

Purpose

This study aimed to investigate the effects of microRNA (miR)-22 on biological behaviors of colon cancer cells and to explore the relationship between miR-22 and NLRP3.

Materials and Methods

First, human colon cancer HCT116 cells were transfected with a miR-22 mimic, miR-22 inhibitor, control mimic, and control inhibitor, respectively. CCK8, colony formation, and transwell assays were performed to observe cell proliferation, migration, and invasion. Western blotting was used to analyze the expression of recombinant NLRP3 (NLR family, pyrin domain-containing protein 3) and epithelial–mesenchymal transformation (EMT)-related proteins. The target relationship between miR-22 and NLRP3 was verified by double luciferase report. Second, an NLRP3 inhibitor and NLRP3 mimic were transfected into HCT116 cells, and the biological behaviors and EMT-related proteins were again observed. Finally, a nude mouse xenograft model was constructed to verify the above results.

Results

In vitro, compared with the control group, administration of the miR-22 mimic significantly decreased proliferation, migration, and invasion of HCT116 cells, whereas the miR-22 inhibitor markedly increased their proliferation and invasion (p<0.05). Levels of NLRP3, interleukin-1β (IL-1β), matrix metalloproteinase-9 (MMP-9), MMP-2, N-cadherin, and vimentin were significantly reduced after miR-22 mimic transfection (p<0.05). Furthermore, silencing of NLRP3, a downstream gene of miR-22 in HCT116 cells, suppressed proliferation, migration, and invasion of HCT116 cells. However, overexpression of NLRP3 weakened the effects of the miR-22 mimic. In vivo, overexpression of miR-22 slowed the growth rate of tumors and reduced Ki-67 expression in tumor tissues compared with the model group (p<0.05). In tumor tissues, overexpression of miR-22 also decreased expression of NLRP3, IL-1β, MMP-9, MMP-2, N-cadherin, and vimentin compared with the model group (p<0.05). Overexpression of NLRP3 weakened the role of miR-22 overexpression in vivo.

Conclusion

miR-22 suppresses cell proliferation, migration, and invasion in colorectal cancer by targeting NLRP3.

miR-22 suppresses cell viability and EMT of ovarian cancer cells via NLRP3 and inhibits PI3K/AKT signaling pathway

PURPOSE

miR-22 plays a great role in inhibiting cell growth, metastasis and enhanced cell apoptosis in several cancers. The purpose of this study was to investigate the functions of miR-22 in ovarian cancer.

METHODS

The proliferative ability was measured using CCK-8 assay. The protein expression associated with EMT and PI3K/AKT signaling biomarkers were measured by western blot. Luciferase assay applied to measure the luciferase activity. Kaplan-Meier method was performed to evaluate the overall survival rate of ovarian cancers.

RESULTS

miR-22 was low expressed and NLRP3 was overexpressed in ovarian cancer tissues and cells, and downregulation of miR-22 was associated with poor prognosis. The expression of NLRP3 had a negative correlation with miR-22 expression in ovarian cancer. miR-22 promoted cell viability and EMT through directly binding to the 3'-UTR of NLRP3 mRNA and inhibited PI3K/AKT signaling pathway. NLRP3 partially restored functions of miR-22 on cell proliferation and EMT in ovarian cancer.

CONCLUSION

miR-22 impaired cell viability and EMT by NLRP3 and inhibited PI3K/AKT signaling pathway in ovarian cancer. The newly identified miR-22/NLRP3/PI3K/AKT axis provides novel insight into the pathogenesis of ovarian cancer.

LncRNA NNT-AS1 promotes lung squamous cell carcinoma progression by regulating the miR-22/FOXM1 axis

Background

Recent studies have revealed that dysregulated expression of long non-coding RNA nicotinamide nucleotide transhydrogenase antisense RNA 1 (lncRNA NNT-AS1) is associated with cell tumorigenicity in non-small cell lung cancer. However, the exact molecular mechanisms of NNT-AS1 in lung squamous cell carcinoma (LUSC) remain largely unknown.

Methods

The expression of NNT-AS1, microRNA (miR)-22 and Forkhead box protein M1 (FOXM1) was measured using quantitative real-time polymerase chain reaction or western blot, respectively. The interaction between miR-22 and NNT-AS1 or FOXM1 was confirmed using a dual-luciferase reporter assay and RNA immunoprecipitation assay. Cell migration and invasion abilities were measured by Transwell assay. Flow cytometry was used to detect apoptotic cells.

Results

NNT-AS1 and FOXM1 were up-regulated but miR-22 was down-regulated in LUSC tissues and cell lines. NNT-AS1 was a sponge of miR-22, and NNT-AS1 deletion suppressed the migration and invasion but induced apoptosis in LUSC cells. FOXM1 was a target of miR-22, and overexpression of miR-22 inhibited cell carcinogenesis in LUSC by targeting FOXM1. Additionally, NNT-AS1 could directly regulate FOXM1 expression by binding to miR-22 in LUSC cells.

Conclusion

LncRNA NNT-AS1 contributes to cell carcinogenesis in LUSC by regulating the miR-22/FOXM1 axis, providing a novel insight into the pathogenesis of LUSC and a new potential therapeutic target for LUSC treatment.

NUP210 and MicroRNA-22 Modulate Fas to Elicit HeLa Cell Cycle Arrest

PURPOSE

Cervical cancer is one of the most fatal diseases among women in under-developed countries. To improve cervical cancer treatment, discovery of new targets is needed. In this study, we investigated the expression of NUP210, miR-22, and Fas in cervical cancer tissues and their functions in cell cycle regulation.

MATERIALS AND METHODS

We detected and compared the expression levels of NUP210, miR-22, and Fas in cervical cancer tissues with paired normal tissues using immunohistochemistry, Western blot, and real-time quantitative polymerase chain reaction. NUP210 was knocked down in HeLa cells via lentivirus, followed by cell cycle and proliferation analysis. Using a luciferase reporter assay, we explored the link between miR-22 and NUP210. We overexpressed miR-22 in HeLa cells and analyzed cell cycle and proliferation function. We then overexpressed miR-22 in NUP210 knockdown cells to explore the connection between Fas and miR-22-NUP210 signaling.

RESULTS

We found that NUP210 was overexpressed in cervical cancer patients. Knocking down NUP210 restored cell apoptosis and proliferation. We confirmed miR-22 as a regulator of NUP210 and verified that miR-22 was inhibited in cervical cancer development. We also found that restoring miR-22 expression could induce cell apoptosis. Finally, we found that miR-22-regulated expression of NUP210 could alter Fas expression and, in turn, elicit cell cycle arrest and proliferation.

CONCLUSION

miR-22 in cervical cancer is downregulated, resulting in NUP210 overexpression and inhibition of Fas-induced cell apoptosis.

Long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 cooperates with enhancer of zeste homolog 2 to promote hepatocellular carcinoma development by modulating the microRNA-22/Snail family transcriptional repressor 1 axis

Metastasis‐associated lung adenocarcinoma transcript 1 (MALAT1) is an oncogenic long noncoding RNA that has been found to promote carcinogenesis and metastasis in many tumors. However, the underlying role of MALAT1 in the progression and metastasis of hepatocellular carcinoma (HCC) remains unclear. In this study, aberrantly elevated levels of MALAT1 were detected in both HCC specimens and cell lines. We found that knockdown of MALAT1 caused retardation in proliferation, migration, and invasion both in vivo and in vitro. Mechanistic investigations showed that Snail family transcriptional repressor 1 (SNAI1) is a direct target of microRNA (miR)‐22 and that MALAT1 modulates SNAI1 expression by acting as a competing endogenous RNA for miR‐22. Inhibition of miR‐22 restored SNAI1 expression suppressed by MALAT1 knockdown. Furthermore, MALAT1 facilitated the enrichment of enhancer of zeste homolog 2 (EZH2) at the promoter region of miR‐22 and E‐cadherin, which was repressed by MALAT1 knockdown. Cooperating with EZH2, MALAT1 positively regulated SNAI1 by repressing miR‐22 and inhibiting E‐cadherin expression, playing a vital role in epithelial to mesenchymal transition. In conclusion, our results reveal a mechanism by which MALAT1 promotes HCC progression and provides a potential target for HCC therapy.

[Effect of recombinant adenovirus Ad-mir-22 on glucose uptake in HepG2 cells]

The recombinant adenoviruses expressing miR-22 (Ad-miR-22) was constructed and the effect of Ad-miR-22 on insulin signal pathway and glucose uptake in HepG2 cells was analyzed. MiR-22 gene was amplified by PCR from human hepatocytes and cloned into the pAdTrack-CMV vector to generate the shuttle plasmid pAdT-22. The positive colonies were confirmed by PCR and sequencing. The resultant shuttle plasmid was linearized with Pme I, followed by co-transformation into competent BJ5183 cells containing an adenoviral backbone plasmid (pAdEasy-1) to create the recombinant plasmid pAd-miR-22. After digested with Pac I, the linearized pAd-miR-22 was transfected into 293A packaging cell line to generate recombinant adenoviruses Ad-miR-22. HepG2 cells were infected with Ad-miR-22 or control Ad-GFP (adenoviruses expressing green fluorescent protein), and then the miR-22 expression levels were analyzed by qPCR. The result shows that adenovirus-mediated overexpression of miR-22 significantly decreased insulin-induced glucose uptake in HepG2 cells. Moreover, overexpression of miR-22 markedly decreased insulin-induced phosphorylation of GSK-3β. miR-22 also increased the mRNA levels of gluconeogenic genes in HepG2 cells. Furthermore, Western blotting results indicate that the protein expression of SIRT1 decreased in Ad-miR-22 infected HepG2 cells as compared with Ad-GFP infected HepG2 cells. In summary, overexpressing of miR-22 significantly increased gluconeogenesis while decreased glucose uptake in HepG2 cells. The effect of miR-22 on glucose metabolism may be mediated by SIRT1.

Downregulation of miR-22 Contributes to Epithelial-Mesenchymal Transition in Osteosarcoma by Targeting Twist1

The epithelial-mesenchymal transition (EMT) is a vital step in osteosarcoma (OS) progression toward metastasis, but the specific molecular events governing this process are incompletely characterized, with miRNAs having increasingly been found to regulate the EMT. In this study, We assessed levels of miR-22 and its target, Twist1, via real-time PCR (qRT-PCR). We further used functional proliferation assays, measures of cell morphology, and western blotting to assess the functional relevance of miR-22 in OS and confirmed Twist1 as a miR-22 target via luciferase reporter assay. We observed a significant decrease in miR-22 levels in OS tumor samples relative to normal tissue, with such downregulating being significantly associated with tumor histological grade. When overexpressed, miR-22 impaired OS cell proliferation and EMT progression. We found Twist1 to be a direct miR-22 target, with levels of miR-22 and Twist1 mRNA being inversely correlated in patient samples. When overexpressed, miR-22 suppressed Twist1 translation and thereby attenuated the EMT in OS cells. These results clearly demonstrate that miR-22 can regulate the EMT in OS cells via targeting Twist1, thus highlighting a potentially novel pathway that can be therapeutically targeted in order to treat OS.

LncRNA CTC-497E21.4 promotes the progression of gastric cancer via modulating miR-22/NET1 axis through RhoA signaling pathway

BACKGROUND

Long non-coding RNAs (lncRNAs) have emerged as important roles in gastric cancer (GC). However, the role of the dysregulated lncRNAs in GC remained large unknown. We investigated the clinical significance, biological function and mechanism of CTC-497E21.4 in GC.

METHODS

Firstly, RTFQ-PCR was used to detect the expression of CTC-497E21.4 in GC. Furthermore, knockdown of CTC-497E21.4 was conducted to assess the effect of CTC-497E21.4 in vitro and vivo. Subcellular localization of CTC-497E21.4 was determined by nuclear plasmolysis PCR and FISH. We also predicted CTC-497E21.4 binding miRNAs and downstream target genes and evaluated its regulation of miR-22 by acting as a ceRNA.

RESULT

CTC-497E21.4 was upregulated in GC tissues and GC cell lines (P < 0.05), and the expression was associated with depth of invasion, lymph node metastasis, and neurological invasion. Besides, knockdown of CTC-497E21.4 inhibited cell proliferation, invasion and promoted cell cycle arrest in vitro and inhibited tumorigenesis in vivo. Mechanistic investigations indicated that CTC-497E21.4 acted as a ceRNA for miR-22 and regulated NET1 expression. CTC-497E21.4/miR-22-3p/NET1 participated in the RhoA signaling pathway in the GC progression.

CONCLUSION

CTC-497E21.4 competed with miR-22 to regulate the expression of NET1 and regulated the malignant progression of GC through RhoA signaling pathway.

MiR-22 suppresses the growth and metastasis of bladder cancer cells by targeting E2F3

Bladder cancer is a common, serious disease worldwide. MicroRNAs (miRNAs) have been reported to participate in the development and progression in many cancers, including bladder cancer. However, the exact roles of miR-22 in bladder cancer process and its underlying mechanism remain largely unknown. The expression levels of miR-22 and E2F3 were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was used to detect the protein levels of E2F3, E-cadherin, N-cadherin, and Vimentin in bladder cancer cells. Cell viability, proliferation, migration, and invasion were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay, colony formation assay, and transwell assay, respectively. The potential binding sites between miR-22 and E2F3 were predicted by TargetScan and verified by luciferase report assay. The expression of miR-22 was downregulated and E2F3 expression was upregulated in bladder cancer tissues and cells. Overexpression of miR-22 or E2F3 knockdown inhibited cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in bladder cancer cells. In addition, E2F3 was a direct target of miR-22 and its knockdown attenuated the promotion of cell proliferation, migration, invasion, and EMT induced by miR-22 inhibitor in bladder cancer cells. In conclusion, miR-22 suppressed cell proliferation, migration, invasion, and EMT in bladder cancer cells by regulating E2F3 expression, providing a novel avenue for treatment of bladder cancer.

Inhibition of miR-22 promotes differentiation of osteoblasts and improves bone formation via the YWHAZ pathway in experimental mice

INTRODUCTION

In senile osteoporosis countering the age-mediated bone loss, promotion of osteoblastogenesis and identification of responsible micro-RNA (miR) would be a successful strategy.

MATERIAL AND METHODS

miR microarray screening was carried out to identify the suppressed miRs after real time polymerase chain reaction (RT-PCR) analysis in mesenchymal stem cells (MSCs) derived from adult bone marrow during the proliferation to the mineralization stage. The primary calvarial pre-osteoblasts (human) were harvested and received transfection of miR-22's antagomir or agomir in vitro. Bioinformatics study suggested YWHAZ as the favorable target gene. Next, YWHAZ knockdown was studied for its effect on differentiation of osteoblasts. For in vivo studies, ovariectomized or sham mice were injected with miR-22's antagomir for a period of 6 weeks. The stromal cells were isolated in the 6^th week for ex vivo experiments.

RESULTS

miR-22 was found to be down-regulated in bone marrow derived mesenchymal stem cells. miR-22's antagomir converted the pre-osteoblasts to a more differentiated and mineralized phenotype showing upregulated protein expression of COL1A1, ALP and CBFA1. The miR-22's antagomir suppressed YWHAZ, enhanced stability of CBFA1 and promoted the differentiation of osteoblasts. In vivo, miR-22's antagomir promoted mineralization and osteoblastogenesis, elevated bone strength and reversed the ovariectomy mediated bone loss in sham mice.

CONCLUSIONS

Inhibition of miR-22 may be a potential target for treating osteoporosis clinically. The findings hence suggest that inhibition of miR-22 may be an effective anabolic therapeutic approach in treating osteoporosis clinically.