Expression Of Signal Transducer And Activator Of Transcription 4 Research Articles

Signal Transducer and Activator of Transcription 4-Induced Up-Regulated LINC01278 Enhances Proliferation and Invasion of Non-Small Cell Lung Cancer Cells via the MicroRNA-877-5p/Activating Transcription Factor 4 Axis.

The purpose of this study was to investigate the specific effects of signal transducer and activator of transcription 4 (STAT4)-induced long intergenic nonprotein coding RNA 1278 (LINC01278) on the growth of non-small cell lung cancer (NSCLC) cells involved in the microRNA (miR)-877-5p/activated transcription factor 4 (ATF4) axis. NSCLC tumor tissue and adjacent normal tissue were collected. Human normal lung epithelial cell BEAS-2B and human NSCLC cell lines (H1299, H1975, A549, H2228) were collected. The expression levels of STAT4, LINC01278, miR-877-5p, and ATF4 were detected. A549 cells were screened for subsequent experiments. The proliferation ability of cells was detected by colony formation experiment. Cell apoptosis was tested by flow cytometry. Scratch test and transwell assay were used to detect the migration and invasion ability of cells. Biological function of LINC01278 in NSCLC was confirmed by xenograft experiments. Low expression miR-877-5p and high expression of STAT4, LINC01278 and ATF4 were detected in NSCLC. Silenced LINC01278 in A549 cell depressed cell proliferation, migration and invasion, but facilitated cell apoptosis. LINC01278 was positively correlated with STAT4 and could directly bind to miR-877-5p. Upregulating miR-877-5p suppressed NSCLC cell progression, while downregulating miR-877-5p had the opposite effect. Upregulating miR-877-5p abrogated the effects of silenced LINC01278 on NSCLC cell progression. MiR-877-5p targeted ATF4. ATF4 upregulation could partly restore the carcinogenic effect of LINC01278 in vitro and in vivo. Our data supports that STAT4-induced upregulation of LINC01278 promotes NSCLC progression by modulating the miR-877-5p/ATF4 axis, suggesting a novel direction for NSCLC treatment.

Divergent roles for STAT4 in shaping differentiation of cytotoxic ILC1 and NK cells during gut inflammation

Natural killer (NK) cells and type 1 innate lymphoid cells (ILC1) require signal transducer and activator of transcription 4 (STAT4) to elicit rapid effector responses and protect against pathogens. By combining genetic and transcriptomic approaches, we uncovered divergent roles for STAT4 in regulating effector differentiation of these functionally related cell types. Stat4 deletion in Ncr1-expressing cells led to impaired NK cell terminal differentiation as well as to an unexpected increased generation of cytotoxic ILC1 during intestinal inflammation. Mechanistically, Stat4-deficient ILC1 exhibited upregulation of gene modules regulated by STAT5 in vivo and an aberrant effector differentiation upon in vitro stimulation with IL-2, used as a prototypical STAT5 activator. Moreover, STAT4 expression in NCR+ innate lymphocytes restrained gut inflammation in the dextran sulfate sodium-induced colitis model limiting pathogenic production of IL-13 from adaptive CD4+ T cells in the large intestine. Collectively, our data shed light on shared and distinctive mechanisms of STAT4-regulated transcriptional control in NK cells and ILC1 required for intestinal inflammatory responses.

SDMA attenuates renal tubulointerstitial fibrosis through inhibition of STAT4

BackgroundRenal tubulointerstitial fibrosis is the hallmark of various chronic kidney diseases. Symmetric dimethylarginine (SDMA) is an independent cardiovascular risk factor in patients with chronic kidney diseases, which is mostly excreted through renal tubules. However, the effect of SDMA on kidneys in a pathological condition is currently unknown. In this study, we investigated the role of SDMA in renal tubulointerstitial fibrosis and explored its underlying mechanisms.MethodsMouse unilateral ureteral obstruction (UUO) and unilateral ischemia–reperfusion injury (UIRI) models were established to study renal tubulointerstitial fibrosis. SDMA was injected into kidneys through ureter retrogradely. TGF-β stimulated human renal epithelial (HK2) cells were used as an in vitro model and treated with SDMA. Signal transducer and activator of transcription-4 (STAT4) was inhibited by berbamine dihydrochloride or siRNA or overexpressed by plasmids in vitro. Masson staining and Western blotting were performed to evaluate renal fibrosis. Quantitative PCR was performed to validate findings derived from RNA sequencing analysis.ResultsWe observed that SDMA (from 0.01 to 10 µM) dose-dependently inhibited the expression of pro-fibrotic markers in TGF-β stimulated HK2 cells. Intrarenal administration of SDMA (2.5 µmol/kg or 25 µmol/kg) dose-dependently attenuated renal fibrosis in UUO kidneys. A significant increase in SDMA concentration (from 19.5 to 117.7 nmol/g, p < 0.001) in mouse kidneys was observed after renal injection which was assessed by LC–MS/MS. We further showed that intrarenal administration of SDMA attenuated renal fibrosis in UIRI induced mouse fibrotic kidneys. Through RNA sequencing analysis, we found that the expression of STAT4 was reduced by SDMA in UUO kidneys, which was further confirmed by quantitative PCR and Western blotting analysis in mouse fibrotic kidneys and renal cells. Inhibition of STAT4 by berbamine dihydrochloride (0.3 mg/ml or 3.3 mg/ml) or siRNA reduced the expression of pro-fibrotic markers in TGF-β stimulated HK2 cells. Furthermore, blockage of STAT4 attenuated the anti-fibrotic effect of SDMA in TGF-β stimulated HK2 cells. Conversely, overexpression of STAT4 reversed the anti-fibrotic effect of SDMA in TGF-β stimulated HK2 cells.ConclusionTaken together, our study indicates that renal SDMA ameliorates renal tubulointerstitial fibrosis through inhibition of STAT4.

Eugenol Essential Oil and Nanoemulsion as Antihydatic Agents with Antifibrotic and Immunomodulatory Effects in Cystic Echinococcosis.

Conventional scolicidal agents are still unsatisfactory in combating hydatid disease due to their low efficacy and increased drug side effects. Therefore, novel scolicides are required. This study aimed to evaluate the antihydatic and immunomodulatory effects of eugenol essential oil (Eug) and its nanoemulsion (Eug-NE) in cystic echinococcosis (CE). Eug and Eug-NE were administered orally to CE-infected rats and compared to albendazole (ABZ). Hydatid cyst development was assessed based on organ weight and hypertrophy indicators of the infected organs, along with a histopathological and histochemical evaluation of collagen content. The immunomodulatory effects of treatment on CE were evaluated by serum cytokine levels measurement of interferon-γ (IFN-γ) and interleukin (IL)-4 and immunohistochemical (IHC) analysis of signal transducer and activator of transcription 4 (STAT4) and GATA-binding protein 3 (GATA3) markers. Eug-NE was the most effective in reducing the cyst weights, organ weights, and hypertrophy indicators and improving histopathological lesions with reduced collagen content. Eug and Eug-NE significantly increased the IFN-γ levels and decreased the IL-4 levels, while IHC analysis demonstrated a significant reduction in STAT4 and GATA3 expression in all treated groups. Eug and Eug-NE demonstrated antihydatic and preventative effects, with a substantial decrease in liver fibrosis compared to that of ABZ. Besides their promising immunomodulatory effects, their good treatment response suggests their use as alternatives or complementary scolicidal agents in hydatid cyst treatment.

STAT4 Play A Critical Role in Aging and High Fat Diet‐Associated Decline in Long‐Term, Activity‐Dependent Potentiation of Synaptic Transmission

Aging and Alzheimer’s disease (AD) both exhibit declines in the magnitude of long‐term, activity‐dependent synaptic potentiation in humans and animals that correlate with declines in cognitive function and long‐term memory in a range of behavioral tasks. Signal Transducer and Activator of Transcription 4 (STAT4) is a transcription factor that is essential for mediating T helper 1 cell differentiation and induction of inflammatory responses to IL‐12. STAT4 plays a vital role in signaling in a range of inflammatory diseases, including cardiovascular inflammation in diabetes, systemic lupus erythematosus and rheumatoid arthritis. It is, however, unknown what role STAT4 plays in central nervous system diseases such as AD, which also have significant inflammatory components to the progression of neurodegeneration. The present study examined the effects of elimination of STAT4 signaling in transgenic mice lacking myeloid cell‐specific STAT4 expression on the expression of long‐term potentiation (LTP) of synaptic transmission, and learning and memory, in mice fed normal versus high‐fat diets. Electrophysiological recordings from Schaffer collateral‐CA1 synapses in hippocampal slices from 3 or 24 week old LysMcreStat4fl/flLdlr‐/‐ mice showed no differences in baseline synaptic transmission, paired‐pulse facilitation (PPF, a measure of presynaptic function), or LTP compared to age‐matched Stat4fl/flLdlr‐/‐ control littermates. Feeding mice a high cholesterol, high carbohydrate diet (DDC) diet from 8‐24 weeks of age resulted in marked, significant impairments in LTP compared to age‐matched mice fed a chow diet, without differences in basal transmission or PPF. In contrast to Stat4fl/flLdlr‐/‐ control mice, LysMcreStat4fl/flLdlr‐/‐ mice receiving the same DDC diet were completely protected from DDC‐associated reductions in LTP. Our current behavioral data support the idea that DDC fed Ldlr‐/‐ mice may experience cognitive and memory declines associated with early AD in comparison with LysMcreStat4fl/flLdlr‐/‐ mice. Taken together, our data support an essential role for the transcription factor STAT4 in the sensitivity of the central nervous system to DDC ‐induced impairments in synaptic plasticity and potentially cognitive function, and suggest that STAT4 pathways are a promising new target for interventions to treat neurodegenerative diseases such as Alzheimer’s, where chronic neuroinflammation is a critical disease mediator.

STAT4 regulates cardiomyocyte apoptosis in rat models of diabetic cardiomyopathy

ObjectiveThis study aimed to investigate the protective role of the signal transducer and activator of transcription 4 (STAT4) in diabetic cardiomyopathy. Materials and methodsMale Sprague-Dawley (SD) rats (6–8 weeks old) were purchased from the Experimental Animal Center of Zhengzhou University. The rats were randomly divided into the control and diabetic cardiomyopathy groups. Rat models of diabetic cardiomyopathy were established by a high-sugar and high-fat diet combined with a peritoneal injection of streptozocin. Pathological changes in the heart were visualized using Hematoxylin-eosin (HE) staining and Masson’s staining. Moreover, cell apoptosis was detected using terminal deoxyribonucleotidyl transferase (TdT)-mediated biotin-16-dUTP nick-end labeling (TUNEL) staining and Annexin V apoptosis detection kit. Furthermore, H9C2 cells were transfected with lentivirus overexpressing STAT4 and treated with high glucose. The CCK-8 assay was performed to determine cell viability. Finally, Western blotting was used to determine the expression of STAT4, Bax, and Bcl-2. ResultsThe myocardial tissue of the diabetic cardiomyopathy models showed hypertrophy, myocardial fibrosis and collagen deposition. Furthermore, TUNEL staining showed increased apoptosis and decreased expression of STAT4 in the myocardial cells. Moreover, the myocardial tissues of the DCM models showed increased expression of Bax/Bcl-2 and a high percentage of Annexin V positive cells. The H9C2 cells showed decreased expression of STAT4 following high glucose treatment. However, the H9C2 cells overexpressing STAT4 showed decreased expression of Bax/Bcl-2 and reduced percentage of Annexin V positive cells. ConclusionThe DCM group had decreased myocardial expression of STAT4. Furthermore, overexpression of STAT4 was shown to reduce high glucose-induced apoptosis.

Regulation of STAT4 by ETS1 in Sjögren syndrome pathogenesis

<h3>Objectives</h3> Primary Sjögren syndrome (pSS) is a chronic autoimmune disease mainly affecting women over the age of 40, causing dry mouth and eyes. The etiology of pSS is complex and includes the overexpression of inflammatory cytokines from affected salivary gland epithelial cells (SGECs). Our group has previously identified candidate biomarkers overexpressed in salivary gland tissues of patients with pSS. We showed that ETS proto-oncogene 1 (ETS1) had higher mRNA and protein expression in pSS salivary glands that correlated with higher levels of lymphocytic infiltration. It has also been shown that the signal transducer and activator of transcription 4 (STAT4) gene contains pSS susceptibility polymorphisms and is a significant mediator of cytokine (ie, interferon, tumor necrosis factor-α) production. Additionally, in previous studies unrelated to pSS, ETS1 was shown to regulate STAT4 expression at the transcription level. Thus, we hypothesized that ETS1 plays a significant role in regulating STAT4 transcription within SGECs of patients with pSS. Our objectives were as follows: (1) to determine whether downregulation of ETS1 mRNA by siRNA knockdown results in decreased mRNA and protein expression of STAT4 within the salivary gland cell line A253 and (2) to demonstrate the regulation of STAT4 mRNA expression by ETS1 siRNA knockdown in cultured SGECs from control patients with pSS and non-pSS sicca. <h3>Methods</h3> The salivary gland cell line, A253, was transfected with siRNA targeting ETS1 or a scrambled siRNA control. After 48 hours, mRNA and protein were isolated. cDNA synthesis was performed using 1 µg of mRNA. Expression of ETS1 and STAT4 mRNA was quantified by quantitative reverse transcription–polymerase chain reaction using the delta cycle threshold method to determine the relative fold changes normalized to glyceraldehyde 3-phosphate dehydrogenase in triplicate experiments. In addition, downregulation of STAT4 protein by ETS1 siRNA was determined by Western blot analysis and semiquantified by densitometry using cofilin as the loading control. SGECs were cultured from labial salivary gland biopsies of 2 patients with pSS (focus score [FS] ≥1) and 4 patients with non-pSS sicca (FS = 0, n = 2; 0 < FS < 1; n = 2) and transfected with siRNA targeting ETS1 or a scrambled siRNA control. After 48 hours, mRNA was isolated for cDNA synthesis and used to determine the mRNA expression of ETS1 and STAT4 as described above. <h3>Results</h3> In A253 cells, STAT4 mRNA expression was changed by −2.15-fold, on average, when treated with siRNA targeting ETS1. STAT4 protein expression was measured by Western blot analysis 48 hours post-ETS1 siRNA knockdown showing an average −1.25-fold change in A253 total cell lysate. SGECs cultured from patients with lymphocytic infiltration (ie, FS >0) showed a significantly higher expression of STAT4 (<i>P</i> = .0485) than patients with non-pSS sicca with FS = 0. However, we did not find a significant change in STAT4 mRNA expression (average, +1.14-fold) in cultured SGECs treated with siRNA targeting ETS1. <h3>Conclusions</h3> STAT4 is overexpressed by cultured SGECs in patients with pSS and those without pSS with focal lymphocytic infiltrates. STAT4 overexpression in SGECs of patients with pSS and those without pSS could be a result of inflammatory cytokine exposure by neighboring cells or effects of infiltrating lymphocyte exposure. Thus, our results suggest a separate regulatory mechanism of STAT4 in pSS bypassing ETS1 regulation, which might be due to pathogenic pathways involving other transcriptional regulation.

Overexpression of STAT4 under hypoxia promotes EMT through miR-200a/STAT4 signal pathway

AimsPrevious reports have found that STAT4 is involved in the epithelial-mesenchymal transition (EMT), thereby regulating the metastasis and invasion of ovarian cancer. However, the mechanisms underlying remain unclear. Main methodsWe first established hypoxia-induced in vivo and in vitro models. The expression levels of signal transducer and activator of transcription 4 (STAT4), the markers of EMT and microRNA-200a (miR-200a) were assessed by western blot and qRT-PCR analysis, respectively. Through the bioinformatics analysis and luciferase assay, the relationship between miR-200a and SATA4 was performed. The gain- and loss-function experiments were performed to examine the role of miR-200a/STAT4 axis. Key findingsThe results showed that the protein level of STAT4 was significantly up-regulated in our hypoxia-exposed models, and contributed to the regulating of EMT. Besides, we found STAT4 was a direct target of miR-200a. Overexpression of miR-200a repressed the expression of STAT4, and inhibited EMT progress, whereas the silencing of miR-200a promoted the STAT4-mediated EMT regulation both in vitro and in vivo. SignificanceOur results provided a potential molecular mechanism by which miR-200a involved in hypoxia-induced metastasis and invasion in ovarian cancer, suggesting a possible target for the treatment of ovarian cancer.

STAT4 sequence variant and elevated gene expression are associated with type 1 diabetes in Polish children.

IntroductionType 1 diabetes (T1D) is caused by the autoimmune destruction of pancreatic β cells, resulting from coincident genetic predisposition and some environmental triggers. Signal transducer and activator of transcription 4 (STAT4) gene encodes a transcription factor, which promotes Th1 cell differentiation, interferon γ production, and development of Th17 cells. Polymorphisms of STAT4 are associated with several autoimmune conditions, while studies in T1D provided inconsistent results. This analysis was designed to investigate the association of STAT4 rs7574865 with T1D in Polish children and to assess STAT4 expression in newly diagnosed subjects.Material and methodsRs7574865 was genotyped in 656 T1D children and 782 healthy individuals. STAT4 mRNA expression was analyzed in peripheral blood mononuclear cells (PBMCs) from 29 children with T1D and 27 age-matched controls. β-cell and thyroid-specific serum autoantibodies were assessed with radioimmunoassays.ResultsThe distribution of rs7574865 genotypes and alleles demonstrated significant difference (p = 0.002, p < 0.001, respectively) between patients vs. controls. Carriers of the minor T allele presented earlier T1D onset (p = 0.017). No differences were found in γ-cell autoantibody in genotype-stratified patients (p > 0.050), while anti-thyroid antibodies were more frequent in carriers of the minor allele(p = 0.039 for anti-thyroperoxidase, p = 0.007 for anti-thyroglobulin antibodies, respectively). STAT4 was overexpressed in PBMCs from T1D patients (p = 0.008), especially subjects with two/three circulating β-cell antibodies (p < 0.001).ConclusionsThe study confirms an association of STAT4 rs7574865 with T1D in Polish patients, and provides an evidence for its relationship with an earlier disease onset and concomitant thyroid autoimmunity. STAT4 expression appears elevated in T1D, especially with more severe reaction against β-cell antigens.

A novel transthyretin/STAT4/miR-223-3p/FBXW7 signaling pathway affects neovascularization in diabetic retinopathy

MicroRNAs (miRNAs) are small RNAs without protein-coding functions that negatively regulate target genes and play important roles in physiological and pathological processes. The aim of this work was to reveal a novel miRNA/gene pathway in diabetic retinopathy (DR). A microarray was used to screen miRNAs in samples from nondiabetic controls and patients with DR, and miR-223-3p was screened as a potential candidate. Quantitative real-time PCR (qRT-PCR) revealed that the level of miR-223-3p was frequently overexpressed in DR samples and human retinal endothelial cells (hRECs) in hyperglycemia, but it was decreased in hyperglycemia after the addition of transthyretin (TTR). In addition, according to cell proliferation, tube formation, and wound healing assays, the downregulation of miR-223-3p suppressed cell migration and proliferation, whereas miR-223-3p upregulation showed the opposite effects. Furthermore, luciferase assays identified F-box and WD repeat domain-containing 7 (FBXW7) as a target mRNA of miR-223-3p. High glucose conditions facilitated the recruitment of signal transducer and activator of transcription 4 (STAT4) and promoted the transcription of miR-223-3p. In hRECs, in a hyperglycemic environment, TTR inhibited STAT4 expression, downregulated the level of miR-223-3p, and finally promoted FBXW7 expression. This study found a novel mechanism whereby TTR might affect neovascularization through a newly identified STAT4/miR-223-3p/FBXW7 cascade in DR.

Silencing of STAT4 Protects Against Autoimmune Myocarditis by Regulating Th1/Th2 Immune Response via Inactivation of the NF-κB Pathway in Rats.

Signal transducer and activator of transcription 4 (STAT4) has been implicated in the progression of myocarditis. The aim of the current study was to investigate the role by which STAT4 influences autoimmune myocarditis in an attempt to identify a theoretical therapeutic perspective for the condition. After successful establishment of an autoimmune myocarditis rat model, the expression patterns of STAT4, NF-κB pathway-related genes, Th1 inflammatory cytokines (IFN-γ and IL-2), and Th2 inflammatory cytokines (IL-6 and IL-10) were subsequently determined. The rats with autoimmune myocarditis were treated with oe-STAT4 or sh-STAT4 lentiviral vectors to evaluate the role of STAT4 in autoimmune myocarditis, or administrated with 1mL 10μmol/L of BAY11-7082 (the NF-κB pathway inhibitor) via tail vein to investigate the effect of the NF-κB pathway on autoimmune myocarditis. Finally, cell apoptosis was evaluated. The serum levels of IFN-γ and IL-2, extent of IκBα and P65 phosphorylation, and the expression of STAT4 were elevated, while the serum levels of IL-6 and IL-10 as well as the expression of IκBα were reduced among the rats with autoimmune myocarditis, which was accompanied by an increase in the apoptotic cells. More importantly, the silencing of STAT4 or the inhibition of the NF-κB pathway was detected to result in a decrease in the serum levels of IFN-γ and IL-2 and an elevation of the serum levels of IL-6 and IL-10, and inhibited myocardial cell apoptosis in rats with autoimmune myocarditis. Moreover, STAT4 silencing was also observed to decrease the extent of IκBα and P65 phosphorylation while acting to elevate the expression of IκBα. Taken together, silencing of STAT4 could hinder the progression of autoimmune myocarditis by balancing the expression of Th1/Th2 inflammatory cytokines via the NF-κB pathway, which may provide a novel target for experimental autoimmune myocarditis (EAM) treatment.

High STAT4 Expression Indicates Better Disease-free Survival in Patients with Gastric Cancer.

The aim of this study was to investigate the significance of signal transducer and activator of transcription 4 (STAT4) expression and the correlation between STAT4 and interferon gamma (IFN-γ) in patients with gastric cancer. Sixty-two patients who underwent gastrectomy for gastric cancer were enrolled in the study. STAT4 and IFNG mRNA expression was evaluated by quantitative real-time polymerase chain reaction (PCR). Immunohistochemistry was performed to examine CD8+ T-cells, and STAT4 and IFN-γ expression. STAT4 mRNA expression was significantly correlated with IFNG mRNA expression (p<0.05). Regarding disease-free survival, there was a significant difference between the groups with high and low STAT4 expression (5-year disease-free survival: 77.8% and 56.4%, p<0.05). Univariate analysis revealed that tumor differentiation and STAT4 expression were significant factors for tumor recurrence. High expression of STAT4 in gastric cancer predicted a better clinical outcome. STAT4 might be a useful biomarker to identify patients at high risk of recurrence after gastrectomy.

Complement Activation and STAT4 Expression Are Associated with Early Inflammation in Diabetic Wounds.

Diabetic non-healing wounds are a major clinical problem. The mechanisms leading to poor wound healing in diabetes are multifactorial but unresolved inflammation may be a major contributing factor. The complement system (CS) is the most potent inflammatory cascade in humans and contributes to poor wound healing in animal models. Signal transducer and activator of transcription 4 (STAT4) is a transcription factor expressed in immune and adipose cells and contributes to upregulation of some inflammatory chemokines and cytokines. Persistent CS and STAT4 expression in diabetic wounds may thus contribute to chronic inflammation and delayed healing. The purpose of this study was to characterize CS and STAT4 in early diabetic wounds using db/db mice as a diabetic skin wound model. The CS was found to be activated early in the diabetic wounds as demonstrated by increased anaphylatoxin C5a in wound fluid and C3-fragment deposition by immunostaining. These changes were associated with a 76% increase in nucleated cells in the wounds of db/db mice vs. controls. The novel classical CS inhibitor, Peptide Inhibitor of Complement C1 (PIC1) reduced inflammation when added directly or saturated in an acellular skin scaffold, as reflected by reduced CS components and leukocyte infiltration. A significant increase in expression of STAT4 and the downstream macrophage chemokine CCL2 and its receptor CCR2 were also found in the early wounds of db/db mice compared to non-diabetic controls. These studies provide evidence for two new promising targets to reduce unresolved inflammation and to improve healing of diabetic skin wounds.

Clinicopathological significance of STAT4 in hepatocellular carcinoma and its effect on cell growth and apoptosis.

BackgroundRecent studies showed that signal transducer and activator of transcription 4 (STAT4) was downregulated in hepatocellular carcinoma (HCC) tissues. However, the role of STAT4 in HCC is still unknown. The aim of this study is to explore the association between STAT4 expression and other clinicopathological features in HCC and to test the effect of STAT4 on cell growth and apoptosis in vitro.MethodsSTAT4 was evaluated by immunohistochemistry in 171 HCC and corresponding paraneoplastic liver, 37 cirrhosis, and 33 normal liver tissues. Association between STAT4 and clinicopathological parameters was analyzed. Meta-analysis on STAT4 in cancer was performed. The effect of STAT4 small interfering RNA (siRNA) on cell growth and cell apoptosis was also detected.ResultsPositive rate of STAT4 was 29.2% (50/171) in HCC tissues, 53.2% (91/171) in paraneoplastic liver tissues, 64.9% (24/37) in cirrhosis tissues, and 72.7% (24/33) in normal liver tissues. STAT4 was upregulated in younger patients who were female, with single tumor node, early TNM stage, without portal vein tumor embolus, and α-fetoprotein (AFP)-positive tumors compared with the groups comprising older patients, males, and those with multiple tumor nodes, advanced TNM stage, with portal vein tumor embolus, and AFP negative tumors. Meta-analysis showed STAT4 was correlated with TNM stage (OR =0.50, 95% CI =0.30, 0.83, P=0.008) and age (OR =0.58, 95% CI =0.38, 0.95, P=0.032) in malignant tissues, and with AFP level (OR =1.76, 95% CI =1.06, 2.94, P=0.03) in HCC. STAT4 siRNA promoted growth and suppressed apoptosis of HepG2 cells.ConclusionSTAT4 might play a vital role in development of HCC, via influencing cell growth and apoptosis, as a tumor suppressor.

Impact of STAT4 expression on cellular immunity and prognosis in hepatocellular carcinoma.

307 Background: Signal transducer and activator of transcription 4 (STAT4) mediates the intracellular effects of IL-12, leading to the production of IFN-γ and cytotoxicity. However, the significance of STAT4 expression in patients with hepatocellular carcinoma (HCC) remains unknown. Herein, we investigated the association of STAT4 expression with cellular immunity and clinicopathological factors in HCC. Methods: A total of 66 HCC patients who underwent hepatic resection were enrolled. RT-PCR was performed to determine STAT4 mRNA and IFN gamma mRNA expression. Immunohistochemistry was performed to examine CD8+ T cells. Results: STAT4 was differentially expressed in tumor and non-tumor tissues (p &lt; 0.01), and positively correlated with IFN gamma and CD8+ T-cell infiltration (p &lt; 0.01). Significant correlations were observed between STAT4 expression and tumor TNM stage, hepatic venous invasion, tumor size, and tumor differentiation. Patients with high STAT4 expression had significantly better disease-free survival (p &lt; 0.01). In addition, low STAT4 expression (p &lt; 0.03) were independent risk factors for tumor recurrence. Conclusions: Down-regulation of STAT4 in HCC indicated aggressive tumor behavior and predicted worse clinical outcome. STAT4 might be a useful biomarker to identify patients with high risk of tumor recurrence after hepatic resection.

High STAT4 expression is a better prognostic indicator in patients with hepatocellular carcinoma after hepatectomy.

Signal transducer and activator of transcription 4 (STAT4) mediates the intracellular effects of interleukin-12, leading to the production of interferon gamma (IFN-γ) and natural killer cells cytotoxicity. However, the clinical significance of STAT4 expression in patients with hepatocellular carcinoma (HCC) remains virtually unknown. A total of 66 HCC patients who underwent hepatectomy were enrolled in this study. Quantitative real-time polymerase chain reaction was performed to determine STAT4 and IFNG mRNA expression levels. Tissue microarray-based immunohistochemistry was performed to examine CD8(+) T cells, STAT4, and INF-γ proteins. STAT4 was differentially expressed in tumor and nontumor tissues (P = 0.001) and positively correlated with IFNG expression (R (2) = 0.506, P < 0.05) and CD8(+) T cell infiltration (R (2) = 0.53, P < 0.001). Significant correlations were observed between STAT4 expression and tumor TNM stage (P = 0.043), hepatic venous invasion (P = 0.003), des-gamma-carboxy prothrombin (P = 0.011), tumor size (P = 0.036), and tumor differentiation (P = 0.034). Patients with high STAT4 expression had significantly better recurrence-free survival (P = 0.009). Low STAT4 expression (P = 0.030) and presence of portal venous invasion or hepatic venous invasion (P = 0.006) were independent risk factors for HCC recurrence. Downregulation of STAT4 in HCC indicated aggressive tumor behavior and predicted a worse clinical outcome. STAT4 might be a useful biomarker to identify patients at high risk of recurrence after hepatectomy.

Effects of microRNA-21 on the interleukin 12/signal transducer and activator of transcription 4 signaling pathway in asthmatic mice

ObjectiveTo study the effect of microRNA-21 (miRNA-21) on the regulation of the interleukin 12 (IL-12)/signal transducer and activator of transcription 4 (STAT4) pathway in the lung tissue of asthmatic mice.Material and methodsForty five male C57BL/6 mice were randomly divided into three groups of 15 mice each: normal control, asthmatic model, and dexamethasone. Our mouse model of allergic asathma was established using OVA sensitization and challenge. Hematoxylin and eosin staining was performed to observe the pathological changes in lung tissue morphology. Both the total cell number and the amount of eosinophils (EOS) in the bronchoalveolar lavage fluid (BALF) were manually counted. The expression of miRNA-21 was detected by real time quantitative PCR. The expression levels of IL-12 and STAT4 in lung tissue were assayed via western blot, and immunohistochemistry was used to observe the distribution of their expression.ResultsThe expression levels of miRNA-21 as well as the total number of BALF cells and EOS were significantly higher in the asthmatic model group than in the control or dexamethasone groups, with significantly higher amounts found in the dexamethasone group than in the control group. The expression levels of IL-12 and STAT4 proteins were lower in the asthmatic model group than in the control and dexamethasone groups, with a significantly lower expression of IL-12 and STAT4 in the dexamethasone group than in the control group.ConclusionsThe expression level of miRNA-21 was significantly increased and the expression level of IL-12 and STAT4 proteins was significantly decreased in allergic asthmatic mice compared with normal control mice. These findings suggest a role for miRNA-21 and the IL-12/STAT4 pathway in the development of allergic asthma.

Abnormal Genetic and Epigenetic Changes in Signal Transducer and Activator of Transcription 4 in the Pathogenesis of Inflammatory Bowel Diseases

Changes in the expression of signal transducer and activator of transcription 4 (STAT4) contribute to the development of a variety of autoimmune diseases including inflammatory bowel diseases (IBDs). Moreover, epigenetic modifications, including DNA methylation, are considered a basis for differentiation of T helper cells and regulation of cytokines. In this study, we investigated the methylation status of STAT4 gene in IBD patients and the associations between its genetic and epigenetic alterations in IBD patients. Blood and colonic mucosa samples were obtained from Korean patients with IBD and healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated, and total RNA and genomic DNA were isolated from the PBMCs and colon mucosa tissues. The mRNA level and DNA methylation status of the promoter were determined by real-time RT-PCR and pyrosequencing, respectively. The chosen SNPs (rs11889341, rs7574865, rs8179673, rs6752770, rs925847, rs10168266, rs10181656, and rs11685878) were genotyped using the TaqMan nuclease assay. Elevated expression of STAT4 was observed in the colonic mucosa and PBMCs of IBD patients. IBD patients showed a lower degree of methylation of the STAT4 promoter than did the healthy controls. Moreover, a significant correlation between risk alleles and methylation status at -172 of the STAT4 promoter was observed, and mRNA levels of STAT4 in IBD patients were correlated inversely with the T-risk allele (rs7574865). Our data demonstrated that the DNA methylation status of STAT4 is associated with genetic polymorphisms, providing insights into the interactions between genetic and epigenetic aberrances in STAT4 that contribute to the development of IBD.

A risk haplotype of STAT4 for systemic lupus erythematosus is over-expressed, correlates with anti-dsDNA and shows additive effects with two risk alleles of IRF5

Systemic lupus erythematosus (SLE) is the prototype autoimmune disease where genes regulated by type I interferon (IFN) are over-expressed and contribute to the disease pathogenesis. Because signal transducer and activator of transcription 4 (STAT4) plays a key role in the type I IFN receptor signaling, we performed a candidate gene study of a comprehensive set of single nucleotide polymorphism (SNPs) in STAT4 in Swedish patients with SLE. We found that 10 out of 53 analyzed SNPs in STAT4 were associated with SLE, with the strongest signal of association (P = 7.1 × 10−8) for two perfectly linked SNPs rs10181656 and rs7582694. The risk alleles of these 10 SNPs form a common risk haplotype for SLE (P = 1.7 × 10−5). According to conditional logistic regression analysis the SNP rs10181656 or rs7582694 accounts for all of the observed association signal. By quantitative analysis of the allelic expression of STAT4 we found that the risk allele of STAT4 was over-expressed in primary human cells of mesenchymal origin, but not in B-cells, and that the risk allele of STAT4 was over-expressed (P = 8.4 × 10−5) in cells carrying the risk haplotype for SLE compared with cells with a non-risk haplotype. The risk allele of the SNP rs7582694 in STAT4 correlated to production of anti-dsDNA (double-stranded DNA) antibodies and displayed a multiplicatively increased, 1.82-fold risk of SLE with two independent risk alleles of the IRF5 (interferon regulatory factor 5) gene.

STAT4 and the proliferation of artery smooth muscle cells in atherosclerosis

Artery smooth muscle cell proliferation is of key importance in the development of atherosclerosis and restenosis following PTCA. In order to understand gene regulation involved in these processes, vascular smooth muscle cells (VSMCs) from atherosclerosis-susceptible White Carneau (WC) and atherosclerosis-resistant Show Racer (SR) pigeons were used to identify transcription factors involved in the enhanced proliferation of WC VSMCs. With protein/DNA array, signal transducer and activator of transcription 4 (STAT4) was found to have over a 10-fold increase in expression in WC compared to SR VSMCs. The difference was confirmed with electrophoretic-mobility shift assay (EMSA) and Western blot. Cells cultured under low serum had 5-fold higher levels of STAT4 in WC compared to SR. By Western analysis, aortic tissue from newly hatched WC pigeons had 1.7–2.0 times greater STAT4 expression than in SR pigeons. A pathway whereby enhanced STAT4 may be associated with enhanced proliferation was identified following IL-12 stimulation of WC VSMCs where 3-fold increases in proliferation and 2-fold higher expression of STAT4 were measured. The findings suggest STAT4 may play a role in VSMC proliferation and describe a unique pigeon model system in which to study STAT4 as a gene target for atherosclerosis therapy.