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.

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.

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.

MicroRNA-22 negatively regulates poly(I:C)-triggered type I interferon and inflammatory cytokine production via targeting mitochondrial antiviral signaling protein (MAVS)

MicroRNAs (miRNAs) are small non-coding RNAs that play important roles in regulating the host immune response. Here we found that miR-22 is induced in glial cells upon stimulation with poly(I:C). Overexpression of miR-22 in the cultured cells resulted in decreased activity of interferon regulatory factor-3 and nuclear factor-kappa B, which in turn led to reduced expression of interferon-β and inflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, interleukin-6, and chemokine (C-C motif) ligand 5, upon stimulation with poly(I:C), whereas knockdown of miR-22 had the opposite effect. We used a combination of bioinformatics and experimental techniques to demonstrate that mitochondrial antiviral signaling protein (MAVS), which positively regulates type I interferon production, is a novel target of miR-22. Overexpression of miR-22 decreased the activity of a luciferase reporter containing the MAVS 3′-untranslated region and led to decreased MAVS mRNA and protein levels. In contrast, ectopic expression of miR-22 inhibitor led to elevated MAVS expression. Collectively, our results demonstrate that miR-22 negatively regulates poly(I:C)-induced production of type I interferon and inflammatory cytokines via targeting MAVS.

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.

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.

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.

MiR-22 functions as a biomarker and regulates cell proliferation, cycle, apoptosis, migration and invasion in renal cell carcinoma

It is well known that microRNAs (miRNAs) are associated with tumor occurrence and development, and the functions of microRNA-22 (miR-22) have been investigated in numerous kinds of cancer. However, the significance of miR-22 in renal cell carcinoma (RCC) has not been fully explored. In this study, we found that miR-22 was down-regulated both in serum and tissues of RCC patients by using real time quantitative PCR (RT-qPCR) analyses. In addition, miR-22 was negatively associated with hepatic metastatic sites and lymphatic metastasis, as well as the clinical stages and prognosis. Moreover, the expression of miR-22 could be increased though surgical treatment in serum of RCC patients. Functional studies were performed to investigate the role of miR-22 in the progression of RCC. Data suggested that overexpression of miR-22 inhibited cell proliferation, migration and invasion in Caki-1 cells, whereas blockage of miR-22 could reverse these oncogenic effects. We also identified erb-b2 receptor tyrosine kinase (ERBB3) was a novel target of miR-22 in RCC cells. Consequently, our work provides evidence that the down-regulation of miR-22 expression contributed to RCC. And miR-22 may be a potential molecule biomarker for diagnose and therapy evaluation in RCC.

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.

Pien Tze Huang induces apoptosis and inhibits proliferation of 5-fluorouracil-resistant colorectal carcinoma cells via increasing miR-22 expression

The well-known traditional Chinese medicine formula Pien Tze Huang (PZH) has long been used to treat various malignancies, including colorectal cancer (CRC). It was recently reported that PZH possesses the ability to overcome multidrug resistance in CRC cells. In the present study, a 5-fluorouracil (5-FU) resistant human CRC cell line (HCT-8/5-FU) was used to further evaluate the effect of PZH on chemotherapy (chemo)-resistance and investigate the mechanisms through which this occurs. The results identified that PZH significantly reduced the viability and cell density of HCT-8/5-FU cells in a dose- and time-dependent manner (P<0.05). PZH inhibited cell survival, reduced the proportion of cells in S-phase, and suppressed the expression of pro-proliferative proteins cyclin D1 and cyclin-dependent kinase 4. In addition, PZH treatment induced nuclear condensation and fragmentation, activated caspase-9 and -3 and increased the pro-apoptotic Bcl-2-associated X protein/B-cell lymphoma 2 protein ratio. Furthermore, PZH treatment upregulated the expression of microRNA-22 (miR-22) and downregulated the expression of c-Myc (a target gene of miR-22). In conclusion, the findings from the present study suggest that PZH can overcome chemo-resistance in cancer cells, likely through increasing miR-22 expression, and by reversing the imbalance between levels of proliferation and apoptosis.

MicroRNA-22 may promote apoptosis and inhibit the proliferation of hypertrophic scar fibroblasts by regulating the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase/p21 pathway

Hypertrophic scarring (HS) is a common skin disorder that occurs during the wound healing process, and the pathogenesis of HS remains unclear. Increasing evidence indicated that specific microRNAs (miRs) may be involved in the onset and progression of HS. In the present study, the association between miR-22 and HS was investigated. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to examine the expression of miR-22 in 30 HS and matched normal skin tissues. In addition, human hypertrophic scar fibroblasts (HSFBs) were cultured and transfected with miR-22 mimics, and MTT and Annexin V apoptosis assays were performed to investigate the role of miR-22 in the proliferation and apoptosis of the human HSFBs. Next, RT-qPCR and western blot assays were performed to compare the expression levels of mitogen-activated protein kinase kinase (MEK), extracellular signal-regulated kinase (ERK) and p21 in untransfected and miR-22 mimic-transfected skin fibroblasts. The results identified that miR-22 was significantly downregulated in HS tissues as compared with the normal skin. Furthermore, transfection with miR-22 mimics in human HSFBs led to inhibited cell proliferation, increased apoptosis, as well as to decreased MEK expression and ERK1/2 phosphorylation, and increased expression of p21. In conclusion, the present study was the first to prove that aberrant expression of miR-22 may serve an important role in the pathogenesis of HS by regulating the MEK/ERK/p21 pathway, thus suggesting that miR-22 has the potential to become a therapeutic target for the treatment of HS.

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.

miR-22 contributes to endosulfan-induced endothelial dysfunction by targeting SRF in HUVECs

microRNAs (miRNAs) function in the posttranscriptional gene regulation, providing new insights into the epigenetic mechanism of toxicity induced by environmental pollutants. miR-22 was discovered to regulate cell proliferation and apoptosis in response to environmental toxicants. We have reported that endosulfan can cause endothelial toxicity in human umbilical vein endothelial cells (HUVECs). In the present study, we investigated the involvement of miR-22 in endosulfan-induced endothelial dysfunction. The expression level of miR-22 was increased in a dose-dependent manner by endosulfan exposure. Overexpression of miR-22 induced apoptosis and inflammation in HUVECs. Anti-miR-22 transfection significantly attenuated the increase in the percentage of apoptotic cells, caspase-3 activity and Interleukin (IL)-6, 8 mRNA levels in endosulfan-exposed HUVECs. Luciferase reporter assay confirmed that SRF and STAG2 were novel direct targets of miR-22. Endosulfan decreased mRNA expression of both SRF and STAG2, but only suppressed protein expression of SRF. Knockdown of SRF via siRNAs resulted in apoptosis and inflammation whereas STAG2 siRNAs only caused abnormal mitosis in HUVECs. Taken together, these findings will shed light on the role and mechanism of miR-22 in endosulfan-induced endothelial dysfunction via SRF in HUVECs.

miR-22 promotes apoptosis of osteosarcoma cells via inducing cell cycle arrest

To study the effects of miR-22 on the proliferation and the apoptosis of osteosarcoma MG-63 cell line and to explore the potential molecular mechanism that miR-22 regulates this biological process. Quantitive real-time polymerase chain reaction (RT-qPCR) was performed to explore the miRNA level of miR-22. The MG-63 cell line was infected with miR-22 mimics for establishment of miR-22 overexpression. Non-infected cells were in blank group and cells infected with empty vector were served as negative control (NC group). MTT assay was conducted to measure cell viability. The cell cycle and apoptosis were explored using flow cytometry and the apoptosis-related markers were detected by western blotting. RT-qPCR results revealed that the miR-22 miRNA level in the MG-63 cells was significantly lower than that in osteoblasts (P<0.05). MTT assay showed that the MG-63 cells infected with miR-22 mimics exhibited markedly decreased proliferation ability compared with blank and empty vector (NC) groups. Next, we found that overexpression of miR-22 remarkably increased the apoptosis of the MG-63 cells, evidenced from the flow cytometry results and elevated Bax and reduced Bcl-2. Furthermore, results revealed that percentage of the cells at G0/G1 phase in miR-22 mimic group (66.75±3.67%) was significantly higher than blank (52.9±2.58%) and NC (50.5±2.45%) groups. miR-22 attenuated the proliferation and induced the apoptosis of the MG-63 cells via promoting G0/G1 cell cycle arrest. Thus, miR-22 may have the potential to be a novel therapeutic in treatment of osteosarcoma.

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.

FosB regulates expression of miR-22 during PMA induced differentiation of K562 cells to megakaryocytes

Expression of many miRNAs is altered in different cancers and these changes are thought to play a key role in formation and progression of cancer. In chronic myelogenous leukemia (CML) a number of miRNAs are known to be down regulated as compared to normal cells. In this report we have investigated the mechanism of this down regulation by using PMA induced differentiation of CML cell line K562 to megakaryocytes as an experimental system. On treatment with PMA, expression of many down regulated miRNAs including miR-22 is induced. PMA also induces expression of several transcription factors, including FosB, EGR1 and EGR2. Our results using a number of approaches, such as promoter reporter assay, FosB knock down and Chip assay, suggest that the expression of miR-22 is regulated transcriptionally by FosB.

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.

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.

NTRK2 is an oncogene and associated with microRNA-22 regulation in human gastric cancer cell lines

In this study, we examined the roles of neurotrophic tyrosine kinase receptor type 2 (NTRK2) gene in regulating in vitro proliferation and invasion in human gastric cancer. Gene expression of NTRK2 was compared between non-carcinoma gastric epithelial cells and gastric cancer (GC) cells by quantitative RT-PCR (qRT-PCR). NTRK2 was either downregulated or upregulated in MKN-28 and SNU-719 cells. The effect of NTRK2 downregulation or upregulation on GC in vitro development was analyzed by qRT-PCR, western blot, proliferation assay, and invasion assay, respectively. The upstream regulator of NTRK2, microRNA-22 (miR-22), was evaluated by dual-luciferase assay. MiR-22 was then upregulated in MKN-28 and SNU-719 cells to examine its regulation on NTRK2 and its encoded protein, tyrosine kinase receptor B (TrkB). In miR-22-upregulated MKN-28 and SNU-719 cells, NTRK2 was further overexpressed to evaluate functional interaction between miR-22 and NTRK2 in GC. NTRK2 was aberrantly upregulated in GC cell lines than in normal gastric cells. In MKN-28 and SNU-719 cells, NTRK2 downregulation inhibited whereas NTRK2 upregulation promoted GC proliferation and invasion in vitro. MiR-22 was verified to be an inverse upstream regulator of NTRK2. In miR-22-upregulated MKN-28 and SNU-719 cells, NTRK2 overexpression partially reversed the miR-22-induced inhibition on cancer proliferation and invasion. NTRK2 is an oncogene and reversely associated with miR-22 in regulating in vitro cancer development in GC.

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.

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.

[Expression of miR-22 and miR-150 in type 1 diabetes mellitus: Possible relationship with autoimmunity and clinical characteristics]

BACKGROUND AND OBJECTIVE

Type 1 diabetes (T1D) is an autoimmune disease of complex aetiology. Several microRNAs (miR) have been linked to the pathogenesis of autoimmune diseases. To analyze the possible association of miR-22 and miR-150 with autoimmunity and clinical severity of T1D.

PATIENTS AND METHODS

The study was performed in peripheral blood mononuclear cells of 20 patients with T1D and 20 control subjects. The expression of miR-22 and miR-150 was performed in peripheral blood mononuclear cells using TaqMan probes to different glucose concentrations (baseline, 11mm, 25mm).

RESULTS

Our results suggest that the expression of miR-22 is increased in T1D patients compared to the controls. This effect was observed in baseline glucose conditions and decreased in 11 and 25mM of glucose. The expression of miR-150 was lower in T1D patients versus the controls. There was no correlation between the autoimmune profile and the two studied miRNAs. miR-22 (baseline condition) and miR-150 (11mM condition) or the ketoacidosis component.

CONCLUSION

miR-22 and 150 were not associated with the autoimmune component present in T1D patients.

Folate deficient tumor microenvironment promotes epithelial-to-mesenchymal transition and cancer stem-like phenotypes

Clinically, serum level of folate has been negatively correlated to the stage and progression of liver cancer. Nevertheless, the functional consequence of folate deficiency (FD) in malignancy has not been fully investigated. Human hepatocellular carcinoma (HCC) cells (as study model) and other cancer types such as lung and glioma were cultured under folate deficient (FD) and folate complete (FD) conditions. Molecular characterization including intracellular ROS/RNS (reactive oxygen/nitrogen species), viability, colony formation, cancer stem-like cell (CSC) phenotype analyses were performed. In vivo tumorigenesis under FD and FC conditions were also examined. FD induced a significant increase in ROS and RNS, suppressing proliferative ability but inducing metastatic potential. Mesenchymal markers such as Snail, ZEB2, and Vimentin were significantly up-regulated while E-cadherin down-regulated. Importantly, CSC markers such as Oct4, β-catenin, CD133 were induced while PRRX1 decreased under FD condition. Furthermore, FD-conditioned HCC cells showed a decreased miR-22 level, leading to the increased expression of its target genes including HDAC4, ZEB2 and Oct4. Finally, xenograft mouse model demonstrated that FD diet promoted tumorigenesis and metastasis as compared to their FC counterparts. Our data provides rationales for the consideration of folate supplement as a metastasis preventive measure.

miR-22 inhibits mouse ovarian granulosa cell apoptosis by targeting SIRT1

Granulosa cell (GC) apoptosis has been shown to be involved in follicular atresia, which is a degenerative process in ovarian follicles of mammals. However, the mechanism underlying the regulation of follicular atresia, particularly by microRNAs, is not well known. Real-time PCR (RT-PCR) was used to detect the expression level of miR-22 in healthy follicles (HF), early atretic follicles (EAF), and progressively atretic follicles (PAF). Flow cytometry was performed to assess the apoptosis of mouse granulosa cells (mGCs) treated with miR-22 mimics or negative control (NC) mimics. Regulation of the expression of SIRT1 by miR-22 was evaluated using a luciferase reporter assay system. To investigate the roles of SIRT1 in mGC apoptosis, the endogenous SIRT1 gene in mGCs was knocked down using an siRNA specific for SIRT1. miR-22 was increased during follicular atresia and suppressed granulosa cell apoptosis. The results of the luciferase reporter assay indicated that SIRT1 was a target gene of miR-22. In addition, knockdown of SIRT1 attenuated apoptosis in mGCs. miR-22 inhibits mGC apoptosis by downregulating SIRT1 directly in vitro. This study provides important insights into understanding the regulation mechanism of ovarian follicle atresia.

Summary: Overexpression of miR-22 inhibits mGC apoptosis by targeting SIRT1, and knockdown of SIRT1 attenuated apoptosis in mGCs. Taken together, these findings provide an improved understanding of the molecular mechanisms of miR-22-mediated follicular development.

miR-22 regulates cell invasion, migration and proliferation in vitro through inhibiting CD147 expression in tongue squamous cell carcinoma

OBJECTIVES

Tongue squamous cell carcinoma (TSCC) is the most common type of head and neck squamous cell carcinoma (HNSCC) in China, and its survival rate remains unsatisfactory. miR-22 has been identified as a tumor suppressor in many human cancers, and high expression of CD147 occurs in many tumors. The aim of the present study was to investigate the expression and function of miR-22 in TSCC and its relationship with the expression of CD147.

METHODS

TCA8113 cells were transiently transfected with a miR-22 mimic/inhibitor. Subsequently, a validation with Real-time RT-PCR was performed to analyze the miR-22 expression level, and a CCK-8 proliferation assay and transwell migration and invasion assays were carried out. Cotransfections using As-miR-22/si-CD147 mRNA or a miR-22/CD147 overexpression vector were applied, and we investigated the biological effects on cotranscribed TCA8113 cells.

RESULTS

qRT-PCR confirmed that miR-22 or As-miR-22 were successfully transfected into TCA8113 cells. Suppressing miR-22 resulted in a promotion of cell proliferation and motility and an up-regulation of CD147 in TCA8113 cells in vitro. In contrast, increasing miR-22 inhibited cell proliferation and motility and down-regulated CD147. Furthermore, the reduction or overexpression of CD147 can reverse the promoting or suppressive effects of miR-22, respectively.

CONCLUSIONS

The down-expression of miR-22 can regulate cell growth and motility in TSCC cells, which indicates that miR-22 acts as a tumor suppressor in TSCC. Additionally, CD147 is subsequently up-regulated when miR-22 inhibited. Taken together, the findings of this research defined a novel relationship between the down-regulation of miR-22 and the up-regulation of CD147 and demonstrated that CD147 is a downstream factor of miR-22.