MicroRNA-22 exerts its neuroprotective and angiogenic functions via regulating PI3K/Akt signaling pathway in cerebral ischemia-reperfusion rats

The aims of this study were to study the effects of miR-2 on cerebral ischemia-reperfusion rats and to explore its further mechanism. Rats were assigned into sham, model, miR-22 control and miR-22 groups. Observation of neurological behaviors at 24 h after operation found that neurological functions were severely damaged in the model and miR-22 control groups and these damages were improved by miR-22. RT-PCR indicated that miR-22 mRNA level in the brain tissue was significantly decreased in the model and miR-22 control groups, but increased in the miR-22 group. TTC staining showed increased percentage of cerebral infarction volume in the model and miR-22 control groups and this increase was reduced by miR-22. Immunohistochemistry showed increased densities of CD34⁺ and VEGF⁺ microvessels in the cortex in the model and miR-22 control groups, which were further increased in the miR-22 group. ELISA showed increased serum VEGF and Ang-1 levels in the model and miR-22 control groups, which were also further increased in the miR-22 group. Western blot analysis showed increased phosphorylation level of PI3K and Akt in brain tissue in the model and miR-22 control groups, which were further increased in the miR-22 group. Administration of LY294002, a specific PI3K pathway inhibitor, significantly reversed all the effects of miR-22 on rats in the model group. miR-22 exerts its neuroprotective and angiogenic functions via the PI3K/Akt signaling pathway, at least partly, in rats under cerebral ischemia-reperfusion.

Galectin-1 promotes hepatocellular carcinoma and the combined therapeutic effect of OTX008 galectin-1 inhibitor and sorafenib in tumor cells

Background

Galectins are beta-galactose specific binding proteins. In human cancers, including hepatocellular carcinoma (HCC), galectin-1 (Gal-1) is often found to be overexpressed. In order to combat the dismal diagnosis and death rates of HCC, gene silencing and targeted inhibition of Gal-1 was investigated for its improved therapeutic potential.

Methods

Cellular and secretory Gal-1 levels were analyzed using HCC clinical samples. The study of Gal-1 was carried by both knockdown and overexpression approaches. The stable clones were tested by in vitro assays and in vivo experiments. Mass spectrometry was used to identify downstream targets of Gal-1. The upstream regulator of Gal-1, microRNA-22 (miR-22) was characterized by functional assays. The therapeutic effect of inhibiting Gal-1 was also analyzed.

Results

Gal-1 overexpression was observed in HCC and correlated with aggressive clinicopathological features and poorer survival. The loss of Gal-1 resulted in hindered cell migration, invasion and anchorage independent growth. This was also observed in the animal models, in that when Gal-1 was knocked down, there were fewer lung metastases. Proteomic profiling of control and Gal-1 knockdown cells identified that the level of retention in endoplasmic reticulum 1 (RER1) was suppressed when Gal-1 level was reduced. The cell motility of Gal-1 knockdown cells was enhanced upon the rescue of RER1 expression. In HCC tissues, Gal-1 and RER1 expressions displayed a significant positive correlation. The upstream regulator of Gal-1, miR-22 was observed to be underexpressed in HCC tissues and negatively correlated with Gal-1. Silencing of miR-22 resulted in the upregulation of Gal-1 and enhanced cell growth, migration and invasion. However, such enhancement was abolished in cells treated with OTX008, an inhibitor of Gal-1. Combinational treatment of OTX008 and sorafenib significantly reduced tumor growth and size.

Conclusions

Gal-1 overexpression was detected in HCC and this played a role in promoting tumorigenic processes and metastasis. The function of Gal-1 was found to be mediated through RER1. The correlations between miR-22, Gal-1 and RER1 expressions demonstrated the importance of miR-22 regulation on Gal-1/RER1 oncogenic activity. Lastly, the combinational treatment of OTX008 and sorafenib proved to be an improved therapeutic option compared to when administering sorafenib alone.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1402-x) contains supplementary material, which is available to authorized users.

IL6R inhibits viability and apoptosis of pancreatic beta-cells in type 2 diabetes mellitus via regulation by miR-22 of the JAK/STAT signaling pathway

BACKGROUND AND AIM

Type 2 diabetes mellitus (T2DM) is a common disease of harming to people's health. MicroRNAs have recently been considered as key regulators of many biological processes, such as cell proliferation, migration and apoptosis. However, the effect of miR-22 expression by targeting IL6 receptor (IL6R) in T2DM and potential molecular mechanism involved remains to be elucidated. The present study aimed to explore the regulatory mechanism of miR-22 by targeting IL6R in pancreatic beta-cells viability and apoptosis of T2DM.

METHODS

The expressions of miR-22, IL6R and apolipoprotein (apoA1, apoB and apoE) were examined by reverse transcription-quantitative PCR (qRT-PCR). Pancreatic beta-cells were transiently transfected with a miR-22 mimic or si-IL6R plasmid which validated with qRT-PCR to analyze the expression of miR-22 or IL6R. Cell viability, apoptosis and protein expression levels were determined by CCK-8, flow cytometry and Western blotting, respectively.

RESULTS

The proportion of INS-1E cell apoptosis was increased in islets of diabetic rats. Furthermore, miR-22 was downregulated and IL6R was upregulated in both diabetic serum and glucose-induced INS-1E cells. miR-22 overexpression or IL6R inhibition significantly strengthened cell viability and reduced the expression of apoptosis-related proteins to suppress cell apoptosis. IL6R was demonstrated as a target gene of miR-22 which could negatively regulate IL6R expression. Moreover, phosphorylation of JAK/STAT signaling pathway was activated by miR-22 overexpression or IL6R inhibition to strengthen the viability and suppress apoptosis of INS-1E cells.

CONCLUSION

This study indicated that miR-22 strengthened the viability and suppressed apoptosis of INS-1E cells, partly by down-regulation of IL6R through the activation of JAK/STAT signaling pathway.

Improved protein expression in HEK293 cells by over-expressing miR-22 and knocking-out its target gene, HIPK1

Stable cell lines can continuously produce a recombinant protein without the need to repeatedly engineer the genome. In a previous study HIPK1, Homeodomain-interacting Protein Kinase 1, was found to be a target of the microRNA miR-22 that, when repressed, improved expression of both an intracellular and a secreted protein. In this report, HEK293 cells stably over-expressing miR-22 were compared with HEK293 with knockout of HIPK1, executed by CRISPR/Cas9, for their ability to improve recombinant protein expression. In this model case of luciferase, over-expression of miR-22 improved overall activity 2.4-fold while the HIPK1 knockout improved overall activity 4.7-fold.

miR-22 Regulates Invasion, Gene Expression and Predicts Overall Survival in Patients with Clear Cell Renal Cell Carcinoma

Background:

Clear cell renal cell carcinoma (ccRCC) is molecularly diverse and distinct molecular subtypes show different clinical outcomes. MicroRNAs (miRNAs) are essential components of gene regulatory networks and play a crucial role in progression of many cancer types including ccRCC.

Objective:

Identify prognostic miRNAs and determine the role of miR-22 in ccRCC.

Methods:

Hierarchical clustering was done in R using gene expression profiles of over 450 ccRCC cases in The Cancer Genome Atlas (TCGA). Kaplan-Meier analysis was performed to identify prognostic miRNAs in the TCGA dataset. RNA-Seq was performed to identify miR-22 target genes in primary ccRCC cells and Matrigel invasion assay was performed to assess the effects of miR-22 overexpression on cell invasion.

Results:

Hierarchical clustering analysis using 2,621 prognostic genes previously identified by our group demonstrated that ccRCC patients with longer overall survival expressed lower levels of genes promoting proliferation or immune responses, while better maintaining gene expression associated with cortical differentiation and cell adhesion. Targets of 26 miRNAs were significantly enriched in the 2,621 prognostic genes and these miRNAs were prognostic by themselves. MiR-22 was associated with poor overall survival in the TCGA dataset. Overexpression of miR-22 promoted invasion of primary ccRCC cells in vitro and modulated transcriptional programs implicated in cancer progression including DNA repair, cell proliferation and invasion.

Conclusions:

Our results suggest that ccRCCs with differential clinical outcomes have distinct transcriptomes for which miRNAs could serve as master regulators. MiR-22, as a master regulator, promotes ccRCC progression at least in part by enhancing cell invasion.

miR-22 enhances the radiosensitivity of small-cell lung cancer by targeting the WRNIP1

Small‐cell lung cancer (SCLC) is an aggressive malignancy characterized by high cellular proliferation and early distant metastasis. Our study aimed to explore the effect of miR‐22‐3p (miR‐22, for short) on SCLC radiosensitivity and its molecular mechanisms. The expression level of miR‐22 was evaluated in a human normal lung epithelial cell line and a human SCLC cell line, and cell apoptosis and migration were detected. The expression of the miR‐22 direct target WRNIP1 mRNA and protein were explored. Five differentially expressed genes were detected. The miR‐22 expression in NCI‐H446 was significantly decreased, and miR‐22 overexpression significantly promoted cell apoptosis. miR‐22 overexpression could significantly inhibit the cell migration of SCLC cells, and miR‐22 had a negative regulatory effect on WRNIP1 mRNA and protein levels. KLK8 was downregulated, and the messenger RNA (mRNA) of four other genes (PC, SCUBE1, STC1, and GPM6A) was upregulated mRNA in cells overexpressing miR‐22, which was in accordance with the bioinformatics analysis. miR‐22 could enhance the radiosensitivity of SCLC by targeting WRNIP1.

Long noncoding RNA C2dat1 protects H9c2 cells against hypoxia injury by downregulating miR-22

Myocardial ischemia is accompanied with hypoxia injury in myocardial cells. Long noncoding RNAs (lncRNA) CAMK2D-associated transcript 1 (C2dat1) C2dat1) has been linked with several ischemic diseases. However, the investigation regarding its role in myocardial ischemia is relatively rare. The aim of this study was to examine the role of C2dat1 in hypoxia response in H9c2 cells. H9c2 cells were subjected to hypoxia to evoke cell damage. Expressions of C2dat1, miR-22, and VEGF in H9c2 cells were altered by transfection, and then cell survival, migration, and invasion were respectively assessed posttransfection. Regulatory relationship between C2dat1, miR-22, and VEGF, as well as the involvement of PI3K/AKT/mTOR and JAK/STAT3 pathways in H9c2 cells injury was then studied. C2dat1 upregulation ameliorated hypoxia injury in H9c2 cells due to the increased viability, migration, and invasion, as well as the decreased apoptosis. miR-22 was negatively regulated by C2dat1. The effects of C2dat1 on H9c2 cells injured by hypoxia were attenuated when miR-22 was overexpressed. VEGF was a target gene of miR-22, and VEGF exerted similar protective effects to C2dat1. Finally, we found that silence of C2dat1 deactivated PI3K/AKT/mTOR and JAK/STAT3 pathways via regulating miR-22 and its downstream gene VEGF. C2dat1-miR-22-VEGF axis could regulate hypoxia injury in H9c2 cells. C2dat1 alleviated hypoxia injury possibly via downregulating miR-22, then upregulating VEGF, which further enhancing the activation of PI3K/AKT/mTOR and JAK/STAT3 pathways.

MicroRNA-22 Suppresses Breast Cancer Cell Growth and Increases Paclitaxel Sensitivity by Targeting NRAS

In recent study, microRNAs have various important functions in diverse biological processes and progression of cancer. In human breast cancer, microRNA-22 has been reported to be downregulated. However, molecular mechanism of microRNA-22 in breast cancer progression and chemosensitivity has not been well studied. In our study, these results demonstrated that microRNA-22 expression levels were significantly reduced in 40 pairs of human breast cancer tissues when compared to normal tissues. Enforced expression of microRNA-22 inhibited activity of cell proliferation and cell migration in breast cancer cells. Furthermore, microRNA-22 targeted NRAS proto-oncogene, GTPase (NRAS) in breast cancer cells. The expression levels of NRAS in human clinical specimens were higher in breast cancer tissues when compared to normal tissues. Moreover, microRNA-22 sensitized breast cancer cells to paclitaxel by regulation of NRAS. Our results then demonstrated that microRNA-22 functioned as a tumor suppressor microRNA and indicated potential application for the diagnosis and treatment of cancer in the future.

Prognostic value and oncogene function of heterogeneous nuclear ribonucleoprotein A1 overexpression in HBV-related hepatocellular carcinoma

Previous study has shown heterogeneous nuclear ribonucleoprotein A1(HNRNPA1) is highly expressed in various human cancers. In order to study the clinical value and potential function of HNRNPA1 in HBV-related hepatocellular carcinoma (HCC), three datasets from the GEPIA, GEO and TCGA were analyzed. HNRNPA1 expression was found to be significantly higher in HBV-positive HCC samples, which was supported with IHC validation. Both GO and KEGG analyses demonstrated that HNRNPA1 co-expressed genes were involved in translation, ribonucleoprotein complex biogenesis and assembly, ribosome biogenesis, RNA processing, RNA splicing, etc. Survival analysis showed a significant reduction in overall survival of patients with high HNRNPA1 expression from both the GSE14520 cohort and 151 patients with HBV-related HCC cohort. Furthermore, Gene set enrichment analysis (GSEA) revealed that HNRNPA1 may regulate HCC progression by influencing the cell cycle and WNT signaling pathway, etc. HNRNPA1 overexpression has diagnostic value in distinguishing between HCC and non-HCC liver tissue (AUC = 0.730). Finally, HNRNPA1 was a directly target gene of miR-22 manifested by the reduced luciferase activity and decreased HNRNPA1 expression in the cells with overexpression of miR-22. HNRNPA1 might function as an oncogene through the EGFR signaling pathway in HBV-related HCC, which has not been reported in previous studies.

Gene expression profiling analysis of the role of miR-22 in clear cell ovarian cancer

This study aimed to investigate the role and potential mechanism of miR-22 in clear cell ovarian cancer (CCOC) progression. The gene expression profile of GSE16568, including 3 CCOC samples with miR-22 overexpression and 3 negative controls, was downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened using the limma package in R. Gene Ontology (GO) and pathway enrichment analysis of DEGs were performed by using The Database for Annotation, Visualization and Integrated Discovery (DAVID). Furthermore, protein-protein interaction (PPI) network of the DEGs was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING) database. Besides, the miR-22-mRNA interaction pairs were predicted to explore the critical genes involved in the cancer. Totally, 95 up-regulated DEGs and 51 down-regulated DEGs were identified. The DEGs were enriched in different GO terms and pathways. The up-regulated genes cyclin-dependent kinases (CDK6), MDM2 oncogene, E3 ubiquitin protein ligase (MDM2), and thrombospondin 1 (THBS1) were involved in the p53 signaling pathway. The up-regulated gene FBJ murine osteosarcoma viral oncogene homolog (FOS) was a hub protein in the PPI network of the DEGs. The down-regulated DEGs including lymphoid enhancer-binding factor 1 (LEF1) and v-myb avian myeloblastosis viral oncogene homolog (MYB) were mainly associated with immunity. Nine DEGs as target genes were identified to be recognized by miR-22. Our study suggested that several key genes such as CDK6, MDM2, LEF1, MYB, and FOS that involved in different pathways including p53 signaling pathway were associated with CCOC progression. miR-22 may play an essential role in cell migration and invasion in CCOC through targeting responsive genes.

Long noncoding RNA MALAT1 promotes high glucose-induced human endothelial cells pyroptosis by affecting NLRP3 expression through competitively binding miR-22

Cell death and inflammation play critical roles in atherosclerosis. Pyroptosis, a novel proinflammatory programmed cell death process, participates in atherosclerosis pathogenesis. Recently, MALAT1 was identified as a pyroptosis-related long noncoding RNA (lncRNA). Here, we investigated the potential role and underlying mechanism of lncRNA MALAT1 in endothelial cells pyroptosis. We first established an endothelial cell pyroptosis model by stimulating EA.hy926 human endothelial cells (EA.hy926 cells) with high glucose. Then, we investigated lncRNA MALAT1 expression and found that it was upregulated in high glucose-treated EA.hy926 cells. Furthermore, lncRNA MALAT1 knockdown significantly inhibited high glucose-induced pyroptosis in EA.hy926 cells, which may critically influence atherosclerosis. Moreover, miR-22 was a target of lncRNA MALAT1 and was negatively correlated with lncRNA MALAT1. NLRP3 expression was significantly suppressed by transfection with a MALAT1-targeting antisense oligonucleotide (ASO). Ultimately, miR-22 overexpression abrogated the effect of MALAT1 on high glucose-induced EA.hy926 cells pyroptosis. Together, our results suggest that lncRNA MALAT1 promotes high glucose-induced pyroptosis of endothelial cells partly by affecting NLRP3 expression through competitively binding miR-22. Our findings indicate a new regulatory mechanism for endothelial cells pyroptosis under high-glucose stress, providing a novel therapeutic target for atherosclerosis.

Oncogenic Activation of Nrf2, Though as a Master Antioxidant Transcription Factor, Liberated by Specific Knockout of the Full-Length Nrf1α that Acts as a Dominant Tumor Repressor

Liver-specific knockout of Nrf1 in the mouse leads to spontaneous development of non- alcoholic steatohepatitis with dyslipidemia, and then its deterioration results in hepatoma, but the underlying mechanism remains elusive to date. A similar pathological model is reconstructed here by using human Nrf1α-specific knockout cell lines. Our evidence has demonstrated that a marked increase of the inflammation marker COX2 definitely occurs in Nrf1α^−/− cells. Loss of Nrf1α leads to hyperactivation of Nrf2, which results from substantial decreases in Keap1, PTEN and most of 26S proteasomal subunits in Nrf1α^−/− cells. Further investigation of xenograft model mice showed that malignant growth of Nrf1α^−/−-derived tumors is almost abolished by silencing of Nrf2, while Nrf1α^+/+-tumor is markedly repressed by an inactive mutant (i.e., Nrf2^−/−ΔTA), but largely unaffected by a priori constitutive activator (i.e., caNrf2^ΔN). Mechanistic studies, combined with transcriptomic sequencing, unraveled a panoramic view of opposing and unifying inter-regulatory cross-talks between Nrf1α and Nrf2 at different layers of the endogenous regulatory networks from multiple signaling towards differential expression profiling of target genes. Collectively, Nrf1α manifests a dominant tumor-suppressive effect by confining Nrf2 oncogenicity. Though as a tumor promoter, Nrf2 can also, in turn, directly activate the transcriptional expression of Nrf1 to form a negative feedback loop. In view of such mutual inter-regulation by between Nrf1α and Nrf2, it should thus be taken severe cautions to interpret the experimental results from loss of Nrf1α, Nrf2 or both.

A dual role of miR-22 in rhabdomyolysis-induced acute kidney injury

AIM

In acute kidney injury (AKI), regions of the kidney are hypoxic. However, for reasons yet unknown, adaptation to hypoxia through hypoxia-inducible factor (HIF) is limited. Here, we studied miR-22, a potential HIF repressor, in normal kidneys, as well as in rhabdomyolysis-induced AKI, a condition where miR-22 is up-regulated.

METHODS

AKI in mice was provoked by IM injection of glycerol. Tissue homogenates were processed to determine the levels of candidate RNAs and proteins, as well as global gene expression profiles. Reporter assays quantified in vitro miR-22 activity and its modulation by mimic or inhibitor molecules, under normoxia or hypoxia (1% O₂ ) respectively. In vivo, anti-miR-22 molecules were applied to normal mice or prior to induction of AKI. Renal outcome was assessed by measuring plasma creatinine, plasma urea and the levels of the injury markers Kim-1 and Ngal.

RESULTS

Renal miR-22 is inducible by hypoxia and represses hypoxia-inducible factor (HIF). Specific inhibition of miR-22 regulates 1913 gene transcripts in kidneys controls and 3386 in AKI, many of which are involved in development or carcinogenesis. Specific inhibition of miR-22 up-regulates tissue protective HIF target genes, yet renal function and injury markers are unchanged or worsened.

CONCLUSIONS

miR-22 is a HIF repressor constitutively expressed in the adult kidney and up-regulated in AKI. Specific inhibition of miR-22 is efficient in vivo and profoundly affects renal gene expression in health and disease, including up-regulation of HIF. However, the net effect on rhabdomyolysis-induced AKI outcome is neutral or even negative.

Effects of miR-22 on viability, migration, invasion and apoptosis in retinoblastoma Y79 cells by targeting high-mobility group box 1

AIM

To explore the effect of miR-22 on viability, migration, invasion and apoptosis in retinoblastoma (RB) Y79 cells and to further detect the potential mechanism.

METHODS

Plasmids were constructed to change the expression level of miR-22 in Y79 cells. Real-time reverse transcription polymerase chain reaction (RT-PCR) was conducted to test the expression level of miR-22. After changing the expression of miR-22, the mRNA and protein levels of high-mobility group box 1 (HMGB1) were investigated using RT-PCR and Western blotting. The effect of miR-22 on viability was analyzed by using cell counting kit-8 (CCK-8) assay and the effect on apoptosis was detected by the flow cytometry. Wound healing migration assay and Transwell invasion assay were used to detect the effects of miR-22 on cell motility.

RESULTS

miR-22 inhibited viability, migration and invasion, while promoting apoptosis, in RB Y79 cells. The inhibition rate of miR-22 overexpression group at 12, 24, 48h was 11.71%±2.54%, 21.36%±1.39% and 29.44%±1.15%, respectively. Cellular apoptosis was higher in miR-22 overexpression group (17.00%±0.39%) compared with negative control (4.38%±0.38%). miR-22 negatively mediated the expression of HMGB1. Furthermore, decreased HMGB1 significantly attenuated viability, migration and invasion, while promoting apoptosis. Enforced expression of HMGB1 partially rescued the effects of miR-22 overexpression on cell viability, migration, invasion and apoptosis. Moreover, the phosphorylated protein kinase B (p-AKT) was significantly downregulated in the HMGB1 shRNA group and miR-22 overexpression group and elevated in the HMGB1 overexpression group compared with the normal control.

CONCLUSION

miR-22 inhibites viability, migration and invasion and increases apoptosis in Y79 cells by targeting HMGB1. These findings may provide a therapeutic strategy for RB.

LncRNA HOX transcript antisense RNA accelerated kidney injury induced by urine-derived sepsis through the miR-22/high mobility group box 1 pathway

OBJECTIVE

This study investigated the role of long noncoding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) in kidney injury induced by urine-derived sepsis (US).

MATERIALS AND METHODS

An Escherichia coli suspension was injected into the distal ureter of adult male Sprague Dawley rats to establish a US model. Lipopolysaccharides (LPSs) were used to induce an in vitro septic model. The interaction between HOTAIR and microRNA 22 (miR-22) was detected by RNA precipitation and RNA pull-down assays. The expression of HOTAIR, miR-22, and high mobility group box 1 (HMGB1) were detected by quantitative real time polymerase chain reaction (qRT-PCR) and Western blot analyses.

RESULTS

Compared with a sham group, HOTAIR was upregulated in kidney tissues of the US group. HOTAIR was also upregulated in LPS-induced human renal tubular epithelial cells (HK-2). Furthermore, HOTAIR negatively regulated miR-22 and promoted apoptosis of HK-2 cells. HOTAIR also promoted HMGB1 expression and HK-2 cell apoptosis by inhibiting miR-22. In addition, the miR-22/HMGB1 pathway was involved in LPS-induced HK-2 cell apoptosis. In vivo experiments showed that HOTAIR negatively modulated miR-22 and positively modulated HMGB1 and that HOTAIR knockdown decreased renal function indicators (blood urea nitrogen [BUN] and serum creatinine).

CONCLUSION

HOTAIR was upregulated in sepsis-induced kidney injury, which promoted HK-2 cell apoptosis in kidney injury through the miR-22/HMGB1 pathway.

The subsequent biological effects of simulated microgravity on endothelial cell growth in HUVECs

PURPOSE

Microgravity is known to cause endothelium dysfunction in astronauts returning from spaceflight. We aimed to reveal the regulatory mechanism in alterations of human endothelial cells after simulated microgravity (SMG).

METHODS

We utilized the rotary cell culture system (RCCS-1) to explore the subsequent effects of SMG on human umbilical vein endothelial cells (HUVECs).

RESULTS

SMG-treated HUVECs appeared obvious growth inhibition after return to normal gravity, which might be attributed to a set of responses including alteration of cytoskeleton, decreased cell adhesion capacity and increased apoptosis. Expression levels of mTOR and its downstream Apaf-1 were increased during subsequent culturing after SMG. miR-22 was up-regulated and its target genes SRF and LAMC1 were down-regulated at mRNA levels. LAMC1 siRNAs reduced cell adhesion rate and inhibited stress fiber formation while SRF siRNAs caused apoptosis.

CONCLUSION

SMG has the subsequent biological effects on HUVECs, resulting in growth inhibition through mTOR signaling and miR-22-mediated mechanism.

miR-22/KAT6B axis is a chemotherapeutic determiner via regulation of PI3k-Akt-NF-kB pathway in tongue squamous cell carcinoma

BACKGROUND

Tongue squamous cell carcinoma (TSCC) is the most common oral cancer. Neoadjuvant systemic treatment before or after surgery for advanced TSCC is considered one of the most crucial factors in reducing mortality. However, the therapeutic benefits of chemotherapy are usually attenuated due to intrinsic and/or acquired drug resistance, and a large proportion of TSCC are resistant to chemotherapy, which may result in more aggressive tumor behavior and an even worse clinical outcome. Recently, the potential application of using miRNAs to predict therapeutic response to cancer treatment holds high promise, but miRNAs with predictive value remain to be identified and underlying mechanisms remain to be understood in TSCC.

METHODS

The expression of miR-22 in tissues from patients diagnosed with TSCC was analyzed using real-time PCR. The effects of miR-22 on cell proliferation and tumorigenesis in TSCC cells were analyzed by MTS assay, and flow cytometry. The tumor growth in vivo was observed in xenograft model. Luciferase reporter assay, real-time PCR and western blot were performed to validate a potential target of miR-22 in TC. The correlation between miR-22 expression and KAT6B expression, as well as the mechanisms by which miR-22 regulates PI3k-Akt-NF-kB pathway in TSCC were also addressed.

RESULTS

We found a strong correlation between miR-22 expression and chemosensitivity to cisplatin (CDDP) in TSCC patients. Ectopic overexpression of miR-22 enhanced TSCC cells apoptosis in response to CDDP in experimental models performed in vitro and in vivo. Moreover, we found that KAT6B is a direct functional target of miR-22. Ectopic expression of KAT6B attenuated the efficiency of miR-22 in TSCC cells upon CDDP treatment. Mechanistically, miR-22 overexpression or KAT6B knockdown inhibited PI3K/Akt/NF-κB signaling in TSCC cells, possibly via downregulating the activators of PI3K/Akt/NF-κB signaling, such as S100A8, PDGF and VEGF. Furthermore, the activation of miR-22 depended on the intensity of the stresses in the presence of p53 activation.

CONCLUSIONS

Our findings define miR-22 as an intrinsic molecular switch that determines p53-dependent cellular fate through KAT6B/ PI3K-Akt/ NF-kB pathway.

Triose-phosphate isomerase is a novel target of miR-22 and miR-28, with implications in tumorigenesis

Aerobic glycolysis is the hallmark of many cancer cells that results in a high rate of adenosine triphosphate (ATP) production and, more importantly, biosynthetic intermediates, which are required by the fast-growing tumor cells. The molecular mechanism responsible for the increased glycolytic influx of tumor cells is still not fully understood. In the present study, we have attempted to address the above question by exploring the role of the glycolytic enzyme, triose-phosphate isomerase (TPI), in the cancer cells. The western blot analysis of the 30 human colorectal cancer samples depicted higher post-transcriptional expression of TPI in the tumor tissue relative to the normal tissue. In addition, we identified two novel microRNAs, miR-22 and miR-28, that target the TPI messenger RNA (mRNA) and regulate its expression. miR-22 and the miR-28 showed significant inverse expression status viz-a-viz the expression of the TPI. The specificity of the miR-22/28 regulation of the TPI mRNA was confirmed by various biochemical and mutagenic assays. Moreover, the hypoxia conditions resulted in an increased expression of the TPI protein, with a concomitant decrease in miR-22/28. The physiological significance of the TPI and miR-22/28 interaction for the glycolytic influx was confirmed by the l-lactate production in the HCT-116^+/+ cells. Overall, our data demonstrate the novel microRNA mediated post-transcriptional regulation of the TPI glycolytic enzyme, which may be one of the possible reasons for the increased glycolytic capacity of the tumor cells.

Serum miR-22 as potential non-invasive predictor of poor clinical outcome in newly diagnosed, uniformly treated patients with diffuse large B-cell lymphoma: an explorative pilot study

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous group of tumors, with aggressive clinical course that renders prognostication and choice of treatment strategy difficult. Chemo-immunotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone (R-CHOP) is the current first-line treatment. MicroRNAs (miRNAs) are under investigation as novel diagnostic and prognostic biomarkers in several malignancies, including malignant lymphomas. While tissue miRNAs in DLBCL patients have been extensively studied as biomarkers, only few reports to date have evaluated the role of circulating/serum miRNAs as potential prognostic factors. Here circulating/serum miRNAs, including miR-22, were investigated as potential non-invasive biomarkers, with the aim of a better prognostic stratification of DLBCL patients.

METHODS

MiRNAs were selected by global expression profile of serum miRNAs of DLBCL patients, The Cancer Genome Atlas (TCGA) analysis and literature research. Serum and tissues miRNA expression profile in de novo DLBCL patients, consecutively enrolled for this study, were detected by quantitative real-time polymerase chain reaction. Relative expression was calculated using the comparative Ct method. Statistical significance was determined using the Mann-Whitney rank sum and Fisher's exact test. Survival analysis was conducted through the use of Kaplan-Meier method. Spearman's Rho was applied to study the correlation between miRNA distributions and days to first relapse. Experimentally validated miRNA-target interactions were assessed by miRTarBase database. Negative miRNA-mRNA correlation was evaluated in TCGA DLBCL dataset. Pathway analysis was performed by the functional annotation clustering DAVID tool.

RESULTS

We showed a significant modulation of serum miR-22 after R-CHOP treatment compared with basal values but no difference between baseline serum miRNAs values of DLBCL patients and healthy controls. High expression level of serum miR-22 in DLBCL at diagnosis (n = 36) is associated with a worse PFS and is independent of the currently used clinical prognostic index. Integrative and pathways analysis of miR-22 identified target genes involved in different important pathways such as p53 signaling.

CONCLUSIONS

Our data suggest that miR-22 is of potential interest as non-invasive biomarker to predict clinical outcome in DLBCL patients. Characterization of miR-22 pathways can pave the way to the development of targeted therapy approaches for specific subgroups of DLBCL patients.

c-Fos-dependent miR-22 targets MDC1 and regulates DNA repair in terminally differentiated cells

Terminally differentiated cells have a reduced capacity to repair double-stranded breaks (DSB) in DNA, however, the underlying molecular mechanism remains unclear. Here, we show that miR-22 is upregulated during postmitotic differentiation of human breast MCF-7 cells, hematopoietic HL60 and K562 cells. Increased expression of miR-22 in differentiated cells was associated with decreased expression of MDC1, a protein that plays a key role in the response to DSBs. This downregulation of MDC1 was accompanied by reduced DSB repair, impaired recruitment of the protein to the site of DNA damage following IR. Conversely, inhibiting miR-22 enhanced MDC1 protein levels, recovered MDC1 foci, fully rescued DSB repair in terminally differentiated cells. Moreover, MDC1 levels, IR-induced MDC1 foci, and the efficiency of DSB repair were fully rescued by siRNA-mediated knockdown of c-Fos in differentiated cells. These findings indicate that the c-Fos/miR-22/MDC1 axis plays a relevant role in DNA repair in terminally differentiated cells, which may facilitate our understanding of molecular mechanism underlying the downregulating DNA repair in differentiated cells.

MicroRNA-22 suppresses the growth, migration and invasion of colorectal cancer cells through a Sp1 negative feedback loop

MicroRNAs have recently emerged as regulators of many biological processes including cell proliferation, development and differentiation. This study identified that miR-22 was statistically decreased in colorectal cancer clinical specimens and highly metastatic cell lines. Moreover, low miR-22 expression was associated with tumor metastasis, advanced clinical stage and relapse. Consistent with clinical observations, miR-22 significantly suppressed the ability of colorectal cancer cells to growth and metastasize in vitro and in vivo. Sp1 was validated as a target of miR-22, and ectopic expression of Sp1 compromised the inhibitory effects of miR-22. In addition, Sp1 repressed miR-22 transcription by binding to the miR-22 promoter, hence forming a negative feedback loop. Further study has shown that miR-22 suppresses the activity of PTEN/AKT pathway by Sp1. Our present results implicate the newly indentified miR-22/Sp1/PTEN/AKT axis might represent a potential therapeutic target for colorectal cancer.

miR-22 regulates C2C12 myoblast proliferation and differentiation by targeting TGFBR1

Recently, miR-22 was found to be differentially expressed in different skeletal muscle growth period, indicated that it might have function in skeletal muscle myogenesis. In this study, we found that the expression of miR-22 was the most in skeletal muscle and was gradually up-regulated during mouse myoblast cell (C2C12 myoblast cell line) differentiation. Overexpression of miR-22 repressed C2C12 myoblast proliferation and promoted myoblast differentiation into myotubes, whereas inhibition of miR-22 showed the opposite results. During myogenesis, we predicted and verified transforming growth factor beta receptor 1 (TGFBR1), a key receptor of the TGF-β/Smad signaling pathway, was a target gene of miR-22. Then, we found miR-22 could regulate the expression of TGFBR1 and down-regulate the Smad3 signaling pathway. Knockdown of TGFBR1 by siRNA suppressed the proliferation of C2C12 cells but induced its differentiation. Conversely, overexpression of TGFBR1 significantly promoted proliferation but inhibited differentiation of the myoblast. Additionally, when C2C12 cells were treated with different concentrations of transforming growth factor beta 1 (TGF-β1), the level of miR-22 in C2C12 cells was reduced. The TGFBR1 protein level was significantly elevated in C2C12 cells treated with TGF-β1. Moreover, miR-22 was able to inhibit TGF-β1-induced TGFBR1 expression in C2C12 cells. Altogether, we demonstrated that TGF-β1 inhibited miR-22 expression in C2C12 cells and miR-22 regulated C2C12 cell myogenesis by targeting TGFBR1.

Evaluation of miR-22 and miR-20a as diagnostic biomarkers for gastric cancer

BACKGROUND

Gastric cancer (GC) is the fourth most common cancers and the second reason for cancer-related death around the world, particularly in East Asian countries. Diagnosing GC in its early stages is followed by more successful treatment. Unfortunately, there is no accurate method for GC diagnosis in its early stages. Recently, miRNAs have been investigated in the most cancer researches which have demonstrated that they have been dysregulated in many cancers.

METHODS

This case-control study aims to investigate the expression rate of miR-22 and miR-20a in 32 cancerous tissues as well as 32 healthy adjacent tissues. Quantitative reverse transcriptase PCR (q-RT PCR) was used for investigating the expression rate of these miRNAs.

RESULTS

The expression rate of miR-20a in cancerous tissues was significantly increased (8.9 times) in comparison with their healthy tissues (P<0.001), while the expression rate of miR-22 in cancerous tissues was significantly decreased (1.9 times) (P<0.05).

CONCLUSIONS

The obtained results suggest miR-22 and miR-20a as good diagnostic biomarkers for early detection of GC. However more research is needed to investigate their efficacy.

MiR-22 down-regulates the proto-oncogene ATP citrate lyase to inhibit the growth and metastasis of breast cancer

Breast cancer, the most common malignancy in women worldwide, places a heavy economic burden and mental stress on families and society. Previous research showed that abnormal expression of miRNAs was closely related to the occurrence, metastasis, and angiogenesis of breast cancer. And in this study, the abnormal expression of miR-22 was detected by RT-PCR in the paired breast cancer tissues and adjacent non-tumor tissues. CCK-8 and wound healing assays were performed to evaluate the effects of the proto-oncogene ATP citrate lyase (ACLY) on the growth and metastasis of breast cancer MCF-7 cells. The results showed that miR-22 inhibited the growth and metastasis of MCF-7 cells by down-regulating the expression of ACLY. In conclusion, this study elucidated the roles of miR-22 in regulation of breast cancer differentiation and migration, which provides a target for early diagnose and therapy of breast cancer.

MicroRNA-22 suppresses cell proliferation, migration and invasion in oral squamous cell carcinoma by targeting NLRP3

MicroRNAs (miRNAs) have been implicated as important regulators of carcinogenesis and tumor development. Recently, microRNA-22 (miR-22) has been reported to be a cancer-related miRNA in several types of tumors. In this study, we aimed to investigate the role of miR-22 in oral squamous cell carcinoma (OSCC). We found that miR-22 expression was significantly decreased in OSCC tissues compared with that in the adjacent noncancerous tissues. Furthermore, lentivirus-mediated miR-22 overexpression markedly reduced OSCC cell viability, migration and invasion, whereas miR-22 inhibitor promoted these parameters. Mechanistically, NLR family pyrin domain containing three (NLRP3) was identified as a direct target of miR-22. miR-22 expression was inversely correlated with NLRP3 expression both in OSCC tissues and cell lines. Moreover, overexpression of miR-22 in OSCC cells could reverse the tumor-promoting effect of the activated NLRP3 inflammasome and vice versus. Therefore, our results indicate that miR-22 may play a suppressive role in OSCC by targeting NLRP3, which offer new insights into the molecular mechanisms of the growth and metastasis of OSCC.