miR-22 inhibits tumor growth and metastasis by targeting ATP citrate lyase: evidence in osteosarcoma, prostate cancer, cervical cancer and lung cancer

MicroRNAs (miRNAs) are non-coding small RNAs that function as negative regulators of gene expression involving in the tumor biology. ATP citrate lyase (ACLY), a key enzyme initiating de novo lipid synthesis, has been found to be upregulated in cancer cells, and its inhibition causes suppressive effects in a variety of tumors. At present, although several ACLY inhibitors have been reported, the potential role of miRNAs in interfering ACLY still needs further clarification. Herein, four different types of tumor cells including osteosarcoma, prostate, cervical and lung cancers were adopted in our study, and we have demonstrated that miR-22 directly downregulated ACLY. Moreover, miR-22 was proved to attenuate cancer cell proliferation and invasion, as well as promote cell apoptosis via inhibiting ACLY. Additionally, we confirmed the higher ACLY protein levels and the lower miR-22 expressions in hundreds of clinical samples of the four primary tumors, and a negative correlation relationship between ACLY and miR-22 was clarified. Finally, in the four animal models, we found that along with the loss of the ACLY expression, the miR-22-treated mice developed rather smaller tumors, less probabilities of distant metastasis, and fairly longer survivals. De novo lipogenesis suppression triggered by miR-22-ACLY axis may contribute to the inhibition of tumor growth and metastasis. These findings provide unequivocal proofs that miR-22 is responsible for the posttranscriptional regulation of ACLY, which yields promising therapeutic effects in osteosarcoma, prostate, cervical and lung cancers.

The Jun/miR-22/HuR regulatory axis contributes to tumourigenesis in colorectal cancer

Background

Colorectal cancer (CRC) is a severe health problem worldwide. Clarifying the mechanisms for the deregulation of oncogenes and tumour suppressors in CRC is vital for its diagnosis, treatment, prognosis and prevention. Hu antigen R (HuR), which is highly upregulated in CRC, functions as a pivotal oncogene to promote CRC progression. However, the underlying cause of its dysregulation is poorly understood.

Methods

In CRC tissue sample pairs, HuR protein levels were measured by Western blot and immunohistochemical (IHC) staining, respectively. HuR mRNA levels were also monitored by qRT-PCR. Combining meta-analysis and microRNA (miRNA) target prediction software, we predicted miRNAs that targeted HuR. Pull-down assay, Western blot and luciferase assay were utilized to demonstrate the direct binding of miR-22 on HuR’s 3’-UTR. The biological effects of HuR and miR-22 were investigated both in vitro by CCK-8, EdU and Transwell assays and in vivo by a xenograft mice model. JASPAR and SABiosciences were used to predict transcriptional factors that could affect miR-22. Luciferase assay was used to explore the validity of putative Jun binding sites for miR-22 regulation. ChIP assay was performed to test the Jun’s occupancy on the C17orf91 promoter.

Results

We observed a significant upregulation of HuR in CRC tissue pairs and confirmed the oncogenic function of HuR both in vitro and in vivo. We found that an important tumour-suppressive miRNA, miR-22, was significantly downregulated in CRC tissues and inversely correlated with HuR in both CRC tissues and CRC cell lines. We demonstrated that miR-22 directly bound to the 3’-UTR of HuR and led to inhibition of HuR protein, which repressed CRC proliferation and migration in vitro and decelerated CRC xenografted tumour growth in vivo. Furthermore, we found that the onco-transcription factor Jun could inhibit the transcription of miR-22.

Conclusions

Our findings highlight the critical roles of the Jun/miR-22/HuR regulatory axis in CRC progression and may provide attractive potential targets for CRC prevention and treatment.

Electronic supplementary material

The online version of this article (10.1186/s12943-017-0751-3) contains supplementary material, which is available to authorized users.

Long non-coding RNA MALAT1 acts as a competing endogenous RNA to promote malignant melanoma growth and metastasis by sponging miR-22

Long non-coding RNAs (lncRNAs) are involved in tumorigenesis. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), an lncRNAs, is associated with the growth and metastasis of many human tumors, but its biological roles in malignant melanoma remain unclear. In this study, the aberrant up-regulation of MALAT1 was detected in melanoma. We determined that MALAT1 promotes melanoma cells proliferation, invasion and migration by sponging miR-22. MiR-22 was decreased and acted as a tumor suppressor in melanoma, and MMP14 and Snail were the functional targets of miR-22. Furthermore, MALAT1 could modulate MMP14 and Snail by operating as a competing endogenous RNA (ceRNA) for miR-22. The effects of MALAT1 in malignant melanoma is verified using a xenograft model. This finding elucidates a new mechanism for MALAT1 in melanoma development and provides a potential target for melanoma therapeutic intervention.

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.

Jak3, STAT3, and STAT5 inhibit expression of miR-22, a novel tumor suppressor microRNA, in cutaneous T-Cell lymphoma

Aberrant activation of Janus kinase-3 (Jak3) and its key down-stream effectors, Signal Transducer and Activator of Transcription-3 (STAT3) and STAT5, is a key feature of malignant transformation in cutaneous T-cell lymphoma (CTCL). However, it remains only partially understood how Jak3/STAT activation promotes lymphomagenesis. Recently, non-coding microRNAs (miRNAs) have been implicated in the pathogenesis of this malignancy. Here, we show that (i) malignant T cells display a decreased expression of a tumor suppressor miRNA, miR-22, when compared to non-malignant T cells, (ii) STAT5 binds the promoter of the miR-22 host gene, and (iii) inhibition of Jak3, STAT3, and STAT5 triggers increased expression of pri-miR-22 and miR-22. Curcumin, a nutrient with anti-Jak3 activity and histone deacetylase inhibitors (HDACi) also trigger increased expression of pri-miR-22 and miR-22. Transfection of malignant T cells with recombinant miR-22 inhibits the expression of validated miR-22 targets including NCoA1, a transcriptional co-activator in others cancers, as well as HDAC6, MAX, MYCBP, PTEN, and CDK2, which have all been implicated in CTCL pathogenesis. In conclusion, we provide the first evidence that de-regulated Jak3/STAT3/STAT5 signalling in CTCL cells represses the expression of the gene encoding miR-22, a novel tumor suppressor miRNA.

miR-22 as a prognostic factor targets glucose transporter protein type 1 in breast cancer

It has been reported that miR-22 plays an important role and may be a promising therapeutic target in cancer. In this study, we found that GLUT1 is a direct target of miR-22. The ectopic expression of miR-22 inhibited breast cancer cell proliferation and invasion by targeting GLUT1. A reverse correlation between the expression of miR-22 and GLUT1 was observed in breast cancer tissue samples. Furthermore, miR-22 was significantly correlated with the TNM stage, local relapse, distant metastasis, and survival of breast cancer patients. Our data suggest that miR-22 functions as a tumor suppressor and is a promising prognostic biomarker in breast cancer.

LncRNA H19 targets miR-22 to modulate H2 O2 -induced deregulation in nucleus pulposus cell senescence, proliferation, and ECM synthesis through Wnt signaling

Intervertebral disc (IVD) degeneration (IDD) is a major contributor to low back pain. During IDD progression, ROS can be produced in the form of H₂ O₂ in nucleus pulposus cells (NPCs) in response to elevated cytokines, leading to subsequent alternations of cell fate and metabolic processes. Genetic factors are considered as main contributors to IDD pathopoiesis. Herein, we investigated the detailed function and mechanism of H19, one of the most up-regulated lncRNAs in IDD specimens, in H₂ O₂ -induced cell senescence model in NPCs. H19 could accelerate H₂ O₂ -induced degenerative changes by promoting cell senescence, increasing ADAMTS-5 and MMPs protein levels and Collagen I content, as well as suppressing NPC proliferation through activating Wnt/β-catenin signaling. Moreover, miR-22, a direct target of H19, could bind to the 3'UTR of LEF1 to inhibit its expression and reverse the effect of H19 on NPCs, thus inhibiting Wnt/β-catenin signaling. Taken together, H19 acts as a ceRNA to compete with LEF1 for miR-22, thus modulating downstream Wnt/β-catenin signaling in NPCs; H19/miR-22/LEF1 might be a novel target for improving H₂ O₂ -induced NPC senescence and treatment for IDD.

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.

Overexpression of miR-22 attenuates oxidative stress injury in diabetic cardiomyopathy via Sirt 1

BACKGROUND/AIMS

Oxidative stress injury is believed to be important in diabetic cardiomyopathy. Recent evidence indicates that miR-22 plays an important role in various cardiovascular diseases, but the protective role of miR-22 in diabetic cardiomyopathy remains undetermined.

METHODS

Diabetes was induced in male C57BL/6 mice by intraperitoneal injection with streptozotocin combined with a high-fat diet, and miR-22 was overexpressed following transfection with adeno-associated virus. Cardiac function was assessed by echocardiography and a cardiac catheter system. In vitro study, H9c2 cells were treated with normal or high glucose (HG), and cell viability or apoptosis was detected using the Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. Reactive oxygen species, malondialdehyde, and superoxide dismutase were also detected in diabetic mice and H9c2 cells. The expression level of miR-22 was detected by real-time PCR. The protein expression of Sirt 1, oxidative stress injury-related proteins (GRP78, CHOP, ATF 3), and apoptosis-related proteins Bax/Bcl-2, cl-casp-9/casp-9, and cl-casp-3/casp-3 were determined by Western blotting analysis.

RESULTS

HG-induced oxidative stress injury and apoptosis were observed in H9c2 cells, which were ameliorated by miR-22. Cardiac dysfunction and severely altered heart structure were also observed in diabetic mice and were dramatically reversed by overexpression of miR-22. The expression of Sirt 1 decreased significantly in diabetic mice and HG-treated H9c2 cells. Overexpression of miR-22 restored the level of Sirt 1. Bioinformatics analysis predicted that Sirt 1 was a potential target gene of miR-22. Luciferase reporter assay verified that miR-22 promoted Sirt 1 expression by direct binding to the Sirt 1 3'untranslated repeats. Upregulation of Sirt 1 could improve cell viability and attenuate oxidative stress injury and apoptosis in the HG-treated H9c2 cells, similar to the effect of miR-22. However, the protective effects of miR-22 against HG-induced oxidative stress injury and apoptosis were abrogated by knockdown of Sirt 1.

CONCLUSIONS

Overexpression of miR-22 can attenuate oxidative stress injury in diabetic cardiomyopathy by upregulation of Sirt 1 in vivo and in vitro.

miR-22 inhibits the proliferation, motility, and invasion of human glioblastoma cells by directly targeting SIRT1

Recently, microRNAs (miRNAs), a kind of small and non-coding RNA, can target the downstream molecules. Increasing evidence demonstrates that miRNAs meditate the onset and progression of a variety of tumors. In the present study, we carried out gene transfection, western blot, and reverse transcription PCR (RT-PCR) to explore the role of miR-22 in glioblastoma tissues and cell lines. Here, we verified that the expression of miR-22 was downregulated in glioblastoma tissues and cells rather than matched non-tumor tissues and normal human astrocyte (NHA) cells (p < 0.001). By contrast, SIRT1 messenger RNA (mRNA) and protein were upregulated in glioblastoma tissues and cells (p < 0.001). In vitro miR-22 mimics interfered with cell proliferation, migration, and invasion of U87 and U251 cells. Mechanically, the 3'-untranslated regions (3'-UTRs) of SIRT1 were a direct target of miR-22, leading to the decreased expression of SIRT1 protein in U87 and U251 cells. Meanwhile, miR-22 mimics also inhibited the expression of epidermal growth factor receptor (EGFR) and matrix metallopeptidase 9 (MMP9). In conclusion, miR-22 inhibited cell proliferation, migration, and invasion via targeting the 3'-UTR of SIRT1 in the progression of glioblastoma and miR-22-SIRT1 pathway can be recommended as a potential target for treatment of glioblastoma.

miR-22 suppresses tumorigenesis and improves radiosensitivity of breast cancer cells by targeting Sirt1

Background

miR-22 has been shown to be frequently downregulated and act as a tumor suppressor in multiple cancers including breast cancers. However, the role of miR-22 in regulating the radioresistance of breast cancer cells, as well as its underlying mechanism is still not well understood.

Methods

The expressions of miR-22 and sirt1 at mRNA and protein levels were examined by qRT-PCR and Western Blot. The effects of miR-22 overexpression and sirt1 knockdown on cell viability, apoptosis, radiosensitivity, γ-H2AX foci formation were evaluated by CCK-8 assay, flow cytometry, colony formation assay, and γ-H2AX foci formation assay, respectively. Luciferase reporter assay and qRT-PCR analysis were performed to confirm the interaction between miR-22 and sirt1.

Results

miR-22 was downregulated and sirt1 was upregulated at both mRNA and protein levels in breast cancer cells. miR-22 overexpression or sirt1 knockdown significantly suppressed viability, induced apoptosis, reduced survival fraction, and increased the number of γ-H2AX foci in breast cancer cells. Sirt1 was identified as a target of miR-22 and miR-22 negatively regulated sirt1 expression. Ectopic expression of sirt1 dramatically reversed the inhibitory effect of miR-22 on cell viability and promotive effect on apoptotic rates and radiosensitivity in breast cancer cells.

Conclusions

miR-22 suppresses tumorigenesis and improves radiosensitivity of breast cancer cells by targeting sirt1, providing a promising therapeutic target for 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.

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.

The circular RNA circ-ITCH acts as a tumour suppressor in osteosarcoma via regulating miR-22

Background: Osteosarcoma (OS) is the most prevailing primary bone tumour and the third prevalent tumour in children and adolescents. Despite advanced treatments, the survival rate of OS has not been effectively improved. Here, we intended to investigate the functional impacts of circ-ITCH on OS. Methods: Circ-ITCH expression in OS tissues and cells was evaluated utilizing qRT-PCR. Viability and proliferation of MG63 and Saos-2 cells were determined by utilizing CCK-8 assay and BrdU assay. Transwell assay was utilized to investigate migration and invasion. Western blot was utilized to distinguish apoptosis and metastasis-related proteins expression. Sequentially, the above-mentioned parameters were reassessed when up-regulating miR-22. Results: Circ-ITCH was low expressed in OS tissues and cells. Overexpressing circ-ITCH facilitated apoptosis and repressed viability, proliferation, migration and invasion in MG63 and Saos-2 cells. MiR-22 expression was reduced by overexpressing circ-ITCH. The decline of viability, proliferation, migration and invasion made by overexpressing circ-ITCH was alleviated by up-regulating miR-22. Conclusively, circ-ITCH suppressed PTEN/PI3K/AKT and SP-1 pathways via down-regulating miR-22. Conclusion: Circ-ITCH took effects on apoptosis, viability, proliferation, migration and invasion through restraining PTEN/PI3K/AKT and SP-1 pathways via down-regulating miR-22 in MG63 and Saos-2 cells. Highlights Low expression of circ-ITCH is observed in osteosarcoma tissues and cell lines; Overexpression circ-ITCH suppresses miR-22 expression; Circ-ITCH promotes proliferation and represses apoptosis by up-regulating miR-22; Circ-ITCH promotes migration and invasion by up-regulating miR-22; Circ-ITCH activates PTEN/PI3K/AKT and SP-1 pathways by up-regulating miR-22.

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.

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.

MiR-22 suppresses the proliferation and invasion of gastric cancer cells by inhibiting CD151

Gastric cancer (GC) is the second common cause of cancer-related death worldwide. microRNAs (miRNAs) play important roles in the carcinogenesis of GC. Here, we found that miR-22 was significantly decreased in GC tissue samples and cell lines. Ectopic overexpression of miR-22 remarkably suppressed cell proliferation and colony formation of GC cells. Moreover, overexpression of miR-22 significantly suppressed migration and invasion of GC cells. CD151 was found to be a target of miR-22. Furthermore, overexpression of CD151 significantly attenuated the tumor suppressive effect of miR-22. Taken together, miR-22 might suppress GC cells growth and motility partially by inhibiting CD151.

MTA1-activated Epi-microRNA-22 regulates E-cadherin and prostate cancer invasiveness

We have previously shown that metastasis-associated protein 1 (MTA1), a chromatin remodeler, plays an important role in prostate cancer invasiveness, likely through regulation of epithelial-to-mesenchymal transition. Here, we identified miR-22 as an epigenetic-microRNA (Epi-miR) directly induced by MTA1 and predicted to target E-cadherin. Loss-of-function and overexpression studies of MTA1 reinforced its regulatory role in miR-22 expression. MiR-22 directly targets the 3'-untranslated region of E-cadherin, and ectopic overexpression of miR-22 diminishes E-cadherin expression. Overexpression of miR-22 in prostate cancer cells promotes cell invasiveness and migration. Meta-analysis of patient tumor samples indicates a positive correlation between MTA1 and miR-22, supporting their inhibitory effect on E-cadherin expression. Our findings implicate the MTA1/Epi-miR-22/E-cadherin axis as a new epigenetic signaling pathway that promotes tumor invasion in prostate cancer.

TIP60-miR-22 axis as a prognostic marker of breast cancer progression

MicroRNAs (miRNAs) are 22- to 24-nucleotide, small, non-coding RNAs that bind to the 3′UTR of target genes to control gene expression. Consequently, their dysregulation contributes to many diseases, including diabetes and cancer. miR-22 is up-regulated in numerous metastatic cancers and recent studies have suggested a role for miR-22 in promoting stemness and metastasis. TIP60 is a lysine acetyl-transferase reported to be down-regulated in cancer but the molecular mechanism of this reduction is still unclear. In this study, we identify TIP60 as a target of miR-22. We show a negative correlation in the expression of TIP60 and miR-22 in breast cancer patients, and show that low levels of TIP60 and high levels of miR-22 are associated with poor overall survival. Furthermore, pathway analysis using high miR-22/low TIP60 and low miR-22/high TIP60 breast cancer patient datasets suggests association of TIP60/miR-22 with epithelial-mesenchymal transition (EMT), a key alteration in progression of cancer cells. We show that blocking endogenous miR-22 can restore TIP60 levels, which in turn decreases the migration and invasion capacity of metastatic breast cancer cell line. These results provide mechanistic insight into TIP60 regulation and evidence for the utility of the combination of TIP60 and miR-22 as prognostic indicator of breast cancer progression.

The inhibition role of miR-22 in hepatocellular carcinoma cell migration and invasion via targeting CD147

BACKGROUND

Recently, miR-22 is identified as a tumor-suppressing microRNA in many human cancers. CD147 is a novel cancer-associated biomarker that plays an important role in the invasion and metastasis of malignant tumor. However, the involvement of miR-22 in CD147 regulation and hepatocellular carcinoma (HCC) progression and metastasis has not been investigated.

METHODS

We measured miR-22 expression level in 34 paired of HCC and matched normal tissues, HCC cell lines by real-time quantitative RT-PCR. Invasion assay, MTT proliferation assay and wound-healing assay were performed to test the invasion and proliferation of HCC cell after overexpression of miR-22. The effect of miR-22 on HCC in vivo was validated by murine xenograft model. The relationship of miR-22 and its target gene CD147 was also investigated.

RESULTS

We found that the expression of miR-22 in HCC tissues and cell lines were much lower than that in normal control, respectively. The expression of miR-22 was inversely correlated with HCC metastatic ability. Moreover, overexpression of miR-22 could significantly inhibit the HCC cell proliferation, migration and invasion in vitro and decrease HCC tumor growth in vivo. Finally, we found that miR-22 interacted with CD147 and decreased its expression, via a specific target site within the CD147 3'UTR by luciferase reporter assay. The expression of CD147 was inversely correlated with miR-22 expression in HCC tissues.

CONCLUSION

Our results suggested that miR-22 was downexpressed in HCC and inhibited HCC cell proliferation, migration and invasion through downregulating cancer-associated gene CD147 which may provide a new bio-target for HCC therapy.

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.

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 targets YWHAZ to inhibit metastasis of hepatocellular carcinoma and its down-regulation predicts a poor survival

Many miRNAs are associated with the carcinogenesis of hepatocellular carcinoma (HCC) and some exhibit potential prognostic value. In this study, to further confirm the prognostic value of miRNAs in HCC, we employed miRNA-sequencing data of tumor tissues of 372 HCC patients released by The Cancer Genome Atlas (TCGA) and identified 3 miRNAs including miR-22, miR-9-1 and miR-9-2 could be used as independent predictors for HCC prognostic evaluation. As a tumor-suppressive miRNA, miR-22 was down-regulated in HCC tissues. This down-regulation correlated with tumor vascular invasion, Edmondson–Steiner grade, TNM stage, and AFP level. Moreover, biofunctional investigations revealed that miR-22 significantly attenuated cellular proliferation, migration and invasion of HCC cells. Additionally, through gene expression profiles and bioinformatics analysis, YWHAZ was identified to be a direct target of miR-22 and its overexpression partially counteracted the inhibitory effects of miR-22 on HCC cells. Finally, molecular studies further confirmed that miR-22 promoted the accumulation of FOXO3a in nucleus and subsequently reversed invasive phenotype of HCC cells by repressing YWHAZ-mediated AKT phosphorylation. Taken together, these data demonstrate that miR-22 exhibits tumor-suppressive effects in HCC cells by regulating YWHAZ/AKT/FOXO3a signaling and might be used as an independent prognostic indicator for HCC patients.

Neuroprotective Role of MicroRNA-22 in a 6-Hydroxydopamine-Induced Cell Model of Parkinson's Disease via Regulation of Its Target Gene TRPM7

Parkinson's disease (PD), the second most prevalent neurodegenerative disorder with only symptomatic treatment available, is characterized by a progressive loss of dopaminergic neurons in the midbrain. Ample evidence indicated that microRNAs (miRs) could regulate post-transcriptional gene expression and neuronal disease. In the present study, we have evaluated the effects and mechanism of miR-22 in PC12 pheochromocytoma cells treated with 6-hydroxydopamine (6-OHDA) to mimic PD. RT-PCR results showed that the expression of miR-22 is downregulated in 6-OHDA-treated PC12 cells, and the overexpression of miR-22 significantly promoted the survival and proliferation of 6-OHDA-induced PC12 cells, whereas miR-22 inhibitor reversed these effects. In addition, PC12 cells were treated with miR-22 mimics or inhibitor following 6-OHDA administration, which medicated ROS production and upregulation or downregulation of caspase-3 activity, respectively. A luciferase reporter assay revealed that transient receptor potential melastatin 7 (TRPM7) is a direct target gene of miR-22, and miR-22 overexpression markedly downregulated the level of TRPM7. Strikingly, further analysis showed that miR-22 mediated 6-OHDA-induced PC12 cell survival and proliferation by targeting TRPM7. Taken together, the present study showed that miR-22 overexpression exhibited neuroprotective and reversal effects on the 6-OHDA-induced PC12 cell growth and apoptosis by targeting TRPM7.

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.