Inhibitory effect of baricitinib on microglia and STAT3 in a region with a weak blood-brain barrier in a mouse model of rheumatoid arthritis.

OBJECTIVES: In patients with RA, baricitinib not only improves arthritis symptom severity, but also patients' neuropsychological symptoms, such as depression and fatigue. However, the cellular mechanisms through which baricitinib can affect neural activity is unexplored. While the blood-brain barrier (BBB) permeability of this drug remains unclear, Janus kinase inhibitors (JAKi) might reach the area postrema, which is a unique brain region with a weak BBB function. Our recent study demonstrated microglial activation during experimental arthritis in the area postrema. Therefore, we sought to assess the effect of baricitinib on microglia in the area postrema using the CIA mouse model. METHODS: Microglia number and morphology in the area postrema were assessed by immunostaining for ionized calcium-binding adaptor molecule-1 (Iba-1). Data were collected on post-immunization day 35 (early phase) and 84 (late phase), and compared between baricitinib- and vehicle-treated mice. The effect on signal transducers and activators of transcription (STAT3) in the area postrema was also immunohistochemically examined. Behavioural outcomes were assessed by examining feeding behaviours and sucrose preference tests. RESULTS: In the early phase, activated microglial levels in the area postrema were decreased by baricitinib, accompanied by the inhibition of phosphorylated-STAT3 and recovery of food intake and sucrose preference. On the other hand, baricitinib did not affect microglial morphology in the late phase. CONCLUSION: Our results demonstrate that baricitinib can affect brain cells, specifically microglia, in the brain region with a weak BBB and mitigate aberrant behaviours during autoimmune arthritis, pointing to the potential therapeutic effect of JAKi on brain pathologies underpinning RA.

Phosphorylated STAT3 suppresses microRNA-19b/1281 to aggravate lung injury in mice with type 2 diabetes mellitus-associated pulmonary tuberculosis.

Type 2 diabetes mellitus (T2DM) is a risk factor for pulmonary tuberculosis (PTB) and increased mortality. This work focused on the functions of phosphorylated STAT3 in lung injury in mouse with T2DM-associated PTB and the molecules involved. A mouse model with T2DM-PTB was induced by administrations of streptozotocin, nicotinamide and mycobacterium tuberculosis (Mtb). A pSTAT3-specific inhibitor AG-490 was given into mice and then the lung injury in mice was observed. The molecules involved in AG-490-mediated events were screened out. Altered expression of miR-19b, miR-1281 and NFAT5 was introduced to identify their involvements and roles in lung injury and PTB severity in the mouse model. Consequently, pSTAT3 expression in mice with T2DM-associated PTB was increased. Down-regulation of pSTAT3 by AG-490 prolonged the lifetime of mice and improved the histopathologic conditions, and inhibited the fibrosis, inflammation, Mtb content and number of apoptotic epithelial cells in mouse lung tissues. pSTAT3 transcriptionally suppressed miR-19b/1281 expression to up-regulate NFAT5. Inhibition of miR-19b/1281 or up-regulation of NFAT5 blocked the protective roles of AG-490 in mouse lung tissues. To conclude, this study evidenced that pSTAT3 promotes NFAT5 expression by suppressing miR-19b/1281 transcription, leading to lung injury aggravation and severity in mice with T2DM-associated PTB.

Loss of leptin receptor-expressing cells in the hindbrain decreases forebrain leptin sensitivity.

Previous studies indicate that inhibition of food intake by leptin is mediated by an integrated response to activation of hypothalamic and hindbrain receptors. This study tested whether loss of hindbrain leptin receptor signaling changed sensitivity to forebrain leptin. Injections of leptin-conjugated saporin (Lep-Sap) into the medial nucleus of the solitary tract (NTS) were used to destroy hindbrain leptin receptor-expressing neurons of male Sprague-Dawley rats. Controls were injected with saporin conjugated with a nonsense peptide (Blk-Sap). Lep-Sap had no effect on daily food intake or body weight, but expression of phosphorylated signal transducer and activator of transcription 3 (pSTAT3) in the NTS following a peripheral injection of leptin was abolished 26 days after Lep-Sap injections. To test forebrain leptin sensitivity, Lep-Sap and Blk-Sap rats received third-ventricle injections of 0, 0.05, 0.1, 0.25, or 0.5 µg leptin. Food intake was inhibited by 0.25 and 0.5 µg leptin in Blk-Sap rats, but there was no significant effect of leptin on food intake of Lep-Sap rats. There was no difference in hypothalamic pSTAT3 in unstimulated conditions, but pSTAT3 was lower in the dorsomedial region of the ventromedial nucleus of the hypothalamus (VMH) of Lep-Sap rats compared with Blk-Sap rats following a third-ventricle injection of 0.25 µg leptin. These results are consistent with previous data showing that loss of VMH leptin receptor-expressing cells prevents weight loss caused by fourth-ventricle leptin infusion and show that the integrated response between the hindbrain and forebrain is heavily dependent on leptin activity in the VMH.

Phosphorylated STAT3 expression predicts better prognosis in smoldering type of adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a mature T-cell neoplasm, and is divided into 2 indolent (smoldering and chronic) and 2 aggressive (acute and lymphoma) clinical subtypes. Based on previous integrated molecular analyses suggesting the importance of the JAK-STAT pathway in ATLL, we attempted to clarify the clinicopathological significance of this pathway. Clinical and morphological findings were reviewed in 116 cases with ATLL. The nuclear localizations of phosphorylated STAT3 (pSTAT3), pSTAT5, and pSTAT6 were analyzed by immunohistochemistry. Targeted sequencing was undertaken on the portion of STAT3 encoding the Src homology 2 domain. Expression of pSTAT3 was observed in 43% (50/116) of ATLL cases, whereas pSTAT5 and pSTAT6 were largely undetected. Cases with the lymphoma type showed significantly less frequent pSTAT3 expression (8/45, 18%) than those with the other subtypes (41/66, 62%; P < .001). STAT3 mutations were detected in 36% (10/28) and 19% (12/64) of cases with the smoldering and aggressive types of ATLL, respectively. The correlation between STAT3 mutation and pSTAT3 expression was not significant (P = .07). Both univariate and multivariate analysis revealed that pSTAT3 expression was significantly associated with better overall survival and progression-free survival in the smoldering type of ATLL, whereas STAT3 mutation was not related to a line of clinical outcome. Collectively, our data show that only the lymphoma type showed a low prevalence of tumor cells positive for pSTAT3 expression, and raises the possibility that pSTAT3 expression is a novel biomarker to predict better prognosis in the smoldering type of ATLL.

The proteasome activator REGγ counteracts immunoproteasome expression and autoimmunity.

For quite a long time, the 11S proteasome activator REGɑ and REGß, but not REGγ, are known to control immunoproteasome and promote antigen processing. Here, we demonstrate that REGγ functions as an inhibitor for immunoproteasome and autoimmune disease. Depletion of REGγ promotes MHC class I-restricted presentation to prime CD8+ T cells in vitro and in vivo. Mice deficient for REGγ have elevation of CD8+ T cells and DCs, and develop age-related spontaneous autoimmune symptoms. Mechanistically, REGγ specifically interacts with phosphorylated STAT3 and promotes its degradation in vitro and in cells. Inhibition of STAT3 dramatically attenuates levels of LMP2/LMP7 and antigen presentation in cells lacking REGγ. Importantly, treatment with STAT3 or LMP2/7 inhibitor prevented accumulation of immune complex in REGγ-/- kidney. Moreover, REGγ-/- mice also expedites Pristane-induced lupus. Bioinformatics and immunohistological analyses of clinical samples have correlated lower expression of REGγ with enhanced expression of phosphorylated STAT3, LMP2 and LMP7 in human Lupus Nephritis. Collectively, our results support the concept that REGγ is a new regulator of immunoproteasome to balance autoimmunity.

MicroRNA-124 regulates STAT3 expression and is down-regulated in colon tissues of pediatric patients with ulcerative colitis.

BACKGROUND & AIMS: Altered levels and functions of microRNAs (miRs) have been associated with inflammatory bowel diseases (IBDs), although little is known about their roles in pediatric IBD. We investigated whether colonic mucosal miRs are altered in children with ulcerative colitis (UC). METHODS: We used a library of 316 miRs to identify those that regulate phosphorylation of signal transducer and activator of transcription 3 (STAT3) in NCM460 human colonocytes incubated with interleukin-6. Levels of miR-124 were measured by real-time polymerase chain reaction analysis of colon biopsies from pediatric and adult patients with UC and patients without IBD (controls), and of HCT-116 colonocytes incubated with 5-aza-2'-deoxycytidine (5-AZA). Methylation of the MIR124 promoter was measured by quantitative methylation-specific polymerase chain reaction. RESULTS: Levels of phosphorylated STAT3 and the genes it regulates (encoding vascular endothelial growth factor (VEGF), BCL2, BCLXL, and matrix metallopeptidase 9 [MMP9]) were increased in pediatric patients with UC compared with control tissues. Overexpression of miR-124, let-7, miR-125, miR-26, or miR-101 reduced STAT3 phosphorylation by ≥ 75% in NCM460 cells; miR-124 had the greatest effect. miR-124 was down-regulated specifically in colon tissues from pediatric patients with UC and directly targeted STAT3 messenger RNA (mRNA). Levels of miR-124 were decreased, whereas levels of STAT3 phosphorylation increased in colon tissues from pediatric patients with active UC compared with those with inactive disease. In addition, levels of miR-124 and STAT3 were inversely correlated in mice with experimental colitis. Down-regulation of miR-124 in tissues from children with UC was attributed to hypermethylation of its promoter region. Incubation of HCT-116 colonocytes with 5-AZA up-regulated miR-124 and reduced levels of STAT3 mRNA. CONCLUSIONS: miR-124 appears to regulate the expression of STAT3. Reduced levels of miR-124 in colon tissues of children with active UC appear to increase expression and activity of STAT3, which could promote inflammation and the pathogenesis of UC in children.

Hes1 promotes the IL-22-mediated antimicrobial response by enhancing STAT3-dependent transcription in human intestinal epithelial cells.

Notch signaling plays an essential role in the proliferation and differentiation of intestinal epithelial cells (IECs). We have previously shown that Notch signaling is up-regulated in the inflamed mucosa of ulcerative colitis (UC) and thereby plays an indispensable role in tissue regeneration. Here we show that in addition to Notch signaling, STAT3 signaling is highly activated in the inflamed mucosa of UC. Forced expression of the Notch target gene Hes1 dramatically enhanced the IL-22-mediated STAT3-dependent transcription in human IECs. This enhancement of STAT3-dependent transcription was achieved by the extended phosphorylation of STAT3 by Hes1. Microarray analysis revealed that Hes1-mediated enhancement of IL-22-STAT3 signaling significantly increased the induction of genes encoding antimicrobial peptides, such as REG1A, REG3A and REG3G, in human IECs. Conversely, the reduction of Hes1 protein levels with a γ-secretase inhibitor significantly down-regulated the induction of those genes in IECs, resulting in a markedly poor response to IL-22. Our present findings identify a new role for the molecular function of Hes1 in which the protein can interact with cytokine signals and regulate the immune response of IECs.

STAT3-mediated attenuation of CCl4-induced mouse liver fibrosis by the protein kinase inhibitor sorafenib.

There have been major advances in defining the immunological events associated with fibrosis in various chronic liver diseases. We have taken advantage of this data to focus on the mechanisms of action of a unique multi-kinase inhibitor, coined sorafenib, on CCl4-induced murine liver fibrosis, including the effects of this agent in models of both acute and chronic CCl4-mediated pathology. Importantly, sorafenib significantly attenuated chronic liver injury and fibrosis, including reduction in liver inflammation and histopathology as well as decreased expression of liver fibrosis-related genes, including α-smooth muscle actin, collagen, matrix metalloproteinases and the tissue inhibitor of metalloproteinase-1. Furthermore, sorafenib treatment resulted in translocation of cytoplasmic STAT3 to the nucleus in its active form. Based on this observation, we used hepatocyte-specific STAT3 knockout (STAT3(Hep-/-)) mice to demonstrate that hepatic STAT3 was critical for sorafenib-mediated protection against liver fibrosis, and that the upregulation of STAT3 phosphorylation was dependent on Kupffer cell-derived IL-6. In conclusion, these data reflect the clinical potential of the multi-kinase inhibitor sorafenib for the prevention of fibrosis as well as the treatment of established liver fibrosis and illustrate the immunological mechanisms that underlie the protective effects of sorafenib.

Gestational exposure to valproic acid upregulates total Stat3 protein expression while downregulating phosphorylated Stat3 in CD-1 mouse embryos with neural tube defects.

Valproic acid (VPA), a widely prescribed antiepileptic drug and an effective treatment for psychiatric disorders, is teratogenic causing neural tube defects (NTDs) and other defects in the exposed embryo. Signal transducer and activator of transcription 3 (Stat3) is a transcription factor that is activated via tyrosine phosphorylation. Stat3, as well as its active form (pYStat3), is expressed during neural tube closure in murine development. This study investigated the effects of in utero VPA exposure on embryonic Stat3 mRNA and protein expression during the critical period of neural tube closure in CD-1 mouse embryos. Following the exposure of CD-1 pregnant mice to the teratogenic dose of 400 mg/kg VPA or saline on gestational day (GD) 9, embryos were harvested at 1, 3, 6, or 24 hr and on GD13. Stat3 mRNA levels remained unchanged at all time points. Total Stat3 protein levels were significantly (p < .05) increased in GD9 embryos at 1 and 6 hr post-exposure and in GD13 exposed nonexencephalic and exencephalic embryo heads. In contrast, phosphorylated Stat3 levels were significantly (p < .05) downregulated in GD9 embryos at the 3 and 6 hr time points with an overall trend of downregulation in the GD10 and GD13 groups. Total and phosphorylated Stat3 protein levels remained unchanged in nuclear extracts of the exposed nonexencephalic and exencephalic GD13 embryo heads. The reported significant downregulation of phosphorylated Stat3 levels suggests its possible role in VPA-induced NTDs in mouse embryos.

A20 ameliorates inflammatory bowel disease in mice via inhibiting NF-κB and STAT3 activation.

A20 is a zinc finger protein that effectively inhibits the activation of nuclear factor (NF)-κB to downregulate the expression of tumor necrosis factor-α, interleukin (IL)-1ß, and IL-17. A20 also plays a crucial role as a feedback inhibitor of the inflammatory response. Due to its inhibitory role, A20 may be useful in regulating diseases resulting from chronic inflammation and excessive pro-inflammatory cytokine production, such as colitis. Patients with colitis produce high levels of pro-inflammatory cytokines in the intestine. Therefore, this study aimed to investigate whether A20 improves experimental colitis by reducing high levels of inflammation in the intestine. An A20 overexpression vector was administered to mice by intrarectal injection after colitis induction. Histological analysis by immunohistochemistry was used to score sections of the intestine. Confocal laser scanning microscopy was used to identify the expression of IL-17 and forkhead box p (FOXP) 3 protein in spleen tissues. Protein expression induced by STAT3 and NF-κB signaling was analyzed by western blot. We found that A20 reduced the colitis activity index score and the histological score of the intestine. A20 also decreased inflammatory cytokine levels in the intestine and increased colon length. Additionally, A20 overexpression downregulated the activation of NF-kB and STAT3. A20 also reduced IL-17 expression in CD4+ T cells from spleen sections. In contrast, A20 overexpression enhanced the expression of FOXP3 in CD4+ T cells. These results suggest that A20 may inhibit the progression of colitis by decreasing inflammation via inhibition of NF-κB, phosphorylated STAT3, and IL-17.

Analgesic effect of AG490, a Janus kinase inhibitor, on oxaliplatin-induced acute neuropathic pain.

Neuropathic pain often occurs during chemotherapy with oxaliplatin. AG490 has been shown to exert an antagonistic effect on inflammatory pain, but its effect on oxaliplatin-induced neuropathic pain remains poorly understood. This study sought to observe the analgesic effect of AG490 on acute neuropathic pain induced by a single oxaliplatin treatment and to address the possible mechanism. In this study, we established a model of oxaliplatin-induced acute neuropathic pain by intraperitoneal injection of 6 mg/kg oxaliplatin. On day 2 after injection, models were intraperitoneally injected with 1, 5, or 10 mg/kg AG490. Paw withdrawal threshold to mechanical stimuli and tail withdrawal latency to cold stimuli were determined. Western blot assay was performed to detect the expression of spinal phosphorylated signal transducer and activator of transcription 3 (p-STAT3). Immunohistochemistry was used to determine the immunoreactivity of p-STAT3 and interleukin-6. Results demonstrated that paw withdrawal threshold and tail withdrawal latency were significantly increased by the treatment of AG490 in rats. There was no significant difference in the effect among the different doses of AG490. AG490 10 mg/kg decreased the expression of p-STAT3, the immunoreactivity of p-STAT3 and interleukin-6 in spinal cord of acute neuropathic pain rats. These findings confirm that AG490 can attenuate oxaliplatin-induced acute neuropathic pain and is associated with the inhibition in the JAK/STAT3 signaling pathway.

Mahuang decoction mitigates airway inflammation and regulates IL-21/STAT3 signaling pathway in rat asthma model.

ETHNOPHARMACOLOGICAL RELEVANCE: Nowadays, bronchial asthma is still a severe disease threatening human health, and it is incumbent upon us to seek effective therapeutic drugs. Mahuang decoction (MHD), a classic famous Chinese prescription, has been used for thousands of years to prevent phlegm from forming, stop coughing and relieve asthma, but the relevant mechanism has not been thoroughly clarified. This study aims to investigate the anti-airway inflammation effect of MHD and the possible molecular mechanism underlying IL21/STAT3 signaling pathway, so as to provide guidance for the treatment of MHD on bronchial asthma. MATERIALS AND METHODS: Specific pathogen free SD rats were randomly divided into 6 groups: normal control group, model group, positive group (Compound methoxyphenamine), MHD-treated groups at doses of 10 ml/kg, 5 ml/kg and 2.5 ml/kg, 10 rats in each group. Except for the normal control group, rats in other groups were sensitized with ovalbumin via introperitoneal injection and challenged with ovalbumin inhalation to trigger asthma model. At 24 h after the last excitation, bronchoalveolar lavage fluid (BALF) of every rat was drawn and the number of inflammatory cells was analyzed using cell counting method. ELISA method was performed to determine the concentrations of TXB2, 6-keto-PGF1α, MMP-9, TIMP-1, IL-2, IL-4, IL-5 and TNF-α in rat serum. The protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in murine pulmonary tissues were assessed with western blotting analysis. RESULTS: Compared with the control group, the airway wall and airway smooth muscle of murine pulmonary tissues significantly thickened and massive inflammatory cells infiltration occurred around the bronchus in the model group, and the cell counts of WBC and EOS in BALF were also apparently increased, which indicated the rat asthma model was successfully established. MHD or Compound methoxyphenamine not only alleviated the pulmonary inflammatory pathological damages, but also down- regulated the numbers of WBC and EOS in BALF. What's more, the levels of TXB2, MMP-9, TIMP-1, ILs-(2, 4, 5) and TNF-α in rat serum were lessened by the treatment of MHD. In western blotting analysis, treatment with 10 ml/kg or 5 ml/kg MHD markedly declined the increased protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in lung tissues of asthmatic rats to normal level. CONCLUSION: MHD intervention demonstrated a strong inhibitory action on the secretion of inflammatory mediators as well as the inflammatory cell infiltration in pulmonary tissues of asthmatic rats, and also depressed the protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in pulmonary tissues. MHD effectively mitigates airway inflammation and regulates the IL-21/STAT3 signaling pathway in rat asthma model.

A new bioassay for measuring the strength of IL-6/STAT3 signal inhibition by tocilizumab in patients with rheumatoid arthritis.

BACKGROUND: Interleukin-6 (IL-6) transduces signals via phosphorylation of STAT3 (pSTAT3). Tocilizumab (TCZ) is an IL-6 receptor blocker, which, when administered intravenously every 4 weeks, efficiently ameliorates rheumatoid arthritis (RA). Since IL-6 signal strength varies among patients with RA, the intensity necessary for appropriate IL-6 signal inhibition by TCZ might vary between individuals. In a previous study, we have examined the clinical utility of increasing (dosing interval shortened to 3 weeks) and decreasing (interval extended to 5 weeks) the dose frequency of TCZ. However, there is currently no established method for accurately measuring the strength of IL-6 signal inhibition by TCZ among individual patients. We therefore sought to develop such an assay. METHODS: Whole blood samples were collected from RA patients with low disease activity (clinical disease activity index (CDAI) ≤ 10) who were treated with TCZ at dosing intervals of 3 weeks (3-week group, n = 10), 4 weeks (4-week group, n = 10) or 5 weeks (5-week group, n = 10), or with methotrexate (control group, n = 10). Recombinant human IL-6 (0, 0.1, 1, 10, 100 ng/ml) was exogenously added to whole blood and the proportion of pSTAT3-positive CD4+ T cells (%pSTAT3+/CD4+) was measured by Phosflow cytometric analysis. RESULTS: The addition of exogenous IL-6 increased the proportion of pSTAT3-positive CD4+ T cells in a dose-dependent manner in each group. Inhibition of IL-6 signaling was strongest in the 3-week dosing group, followed by the 4-week, 5-week and control group. Significant differences in %pSTAT3+/CD4+ cells were observed between dose interval groups when stimulated with 10 ng/ml and 100 ng/ml of IL-6. CONCLUSION: Assessment of the proportion of pSTAT3-positive CD4+ T cells under IL-6 stimulation is a highly sensitive and useful method for determining differences in the strength of IL-6 signal inhibition in patients treated with TCZ. It is suggested that different TCZ treatment intervals were necessary to lower disease activity in each group of patients, and these findings also indicate that the IL-6 signaling pathway may differ in each RA patient. Our assay may support strategies for optimizing TCZ treatment in RA patients.

Bioinformatic analyses reveal a distinct Notch activation induced by STAT3 phosphorylation in the mesenchymal subtype of glioblastoma.

OBJECTIVE Glioblastoma (GBM) is the most common and lethal type of malignant glioma. The Cancer Genome Atlas divides the gene expression-based classification of GBM into classical, mesenchymal, neural, and proneural subtypes, which is important for understanding GBM etiology and for designing effective personalized therapy. Signal transducer and activator of transcription 3 (STAT3), a critical transcriptional activator in tumorigenesis, is persistently phosphorylated and associated with an unfavorable prognosis in GBM. Although a set of specific targets has been identified, there have been no systematic analyses of STAT3 signaling based on GBM subtype. METHODS This study compared STAT3-associated messenger RNA, protein, and microRNA expression profiles across different subtypes of GBM. RESULTS The analyses revealed a prominent role for STAT3 in the mesenchymal but not in other GBM subtypes, which can be reliably used to classify patients with mesenchymal GBM into 2 groups according to phosphorylated STAT3 expression level. Differentially expressed genes suggest an association between Notch and STAT3 signaling in the mesenchymal subtype. Their association was validated in the U87 cell, a malignant glioma cell line annotated as mesenchymal subtype. Specific associated proteins and microRNAs further profile the STAT3 signaling among GBM subtypes. CONCLUSIONS These findings suggest a prominent role for STAT3 signaling in mesenchymal GBM and highlight the importance of identifying signaling pathways that contribute to specific cancer subtypes.

Discovery of oral-available resveratrol-caffeic acid based hybrids inhibiting acetylated and phosphorylated STAT3 protein.

Constitutive activation of STAT3 has been found in a wide variety of cancers and demonstrated as a very attractive therapeutic target. Disrupting both acetylation and phosphorylation of STAT3 protein was hypothesized to greatly deactivate STAT3, therefore, treating cancers. To demonstrate the hypothesis, two series of novel resveratrol-caffeic acid hybrids were designed aiming to regulate both acetylation and phosphorylation of STAT3 protein, which is also the first report of the synthetic inhibitors simultaneously regulating two biological reactions of STAT3 to our knowledge. Most of these compounds were demonstrated with preferential antitumor activity with low IC50 values against two cancer cell lines. Particularly, compound 7d was found as an excellent STAT3 inhibitor with over 50-fold better potency than resveratrol and caffeic acid. Meanwhile, the novel derivatives significantly inhibited the proliferation and induced the apoptosis of tumor cells. Molecular docking further disclosed the binding modes of STAT3 with the inhibitors. In addition, compound 7d orally and significantly suppressed breast cancer 4T1 xenograft tumor growth in vivo, indicating its great potential as an efficacious drug candidate for human cancer therapy.

Prognostic significance of STAT3/phosphorylated-STAT3 in tumor: a meta-analysis of literatures.

PURPOSE: The prognostic value of the expression of STAT3/phosphorylated-STAT3 on survival for cancer patients remains controversial. We performed a meta-analysis of the published literature in this field to identify its impact. METHODS: We conducted a meta-analysis of 26 studies (n=3877 patients) that evaluated the relationship between the prognostic value and the expression of STAT3/phosphorylated-STAT3 in 15 different kinds of carcinomas. Studies evaluated the correlation between STAT3/phosphorylated-STAT3, which detected mostly by immunohistochemistry and western blot, and clinical staging, overall survival (OS) and disease free survival (DFS) were included. The impact of STAT3 and phosphorylated-STAT3 was analyzed separately. RESULTS: A total of 26 studies (14 for STAT3 and 16 for phosphorylated-STAT3), comprising 3877 patients, were included for meta-analysis. The expression of STAT3 was strongly associated with a poor impact on overall survival (OS) in all eligible studies [hazard ratio (HR)=2.91, (95% confidence interval (CI), 1.91-4.42)], while a significant association was shown between the expression of phosphorylated-STAT3 and patients' outcome [HR=1.53, (95% CI, 0.86-2.70)]. No significant effect was shown between the expression of STAT3/phosphorylated-STAT3 and clinical staging, neither with DFS. CONCLUSION: High expression of STAT3 seems to be associated with poor OS in patients with carcinomas, while phosphorylated-STAT3 does not.

A meta-analysis of STAT3 and phospho-STAT3 expression and survival of patients with non-small-cell lung cancer.

BACKGROUND: The prognostic role of signal transducer and activator of transcription 3 (STAT3) and phospho-STAT3 in non-small-cell lung cancer (NSCLC) remains controversial. To clarify its impact on survival, we performed a meta-analysis to quantitatively assess STAT3 and phospho-STAT3 expression on the prognosis of NSCLC. METHODS: Published studies were identified using a systematic and thorough literature search. To be eligible, a study had to investigate STAT3 or phospho-STAT3 expression rates of NSCLC patients in different characteristics and provide patient survival data. RESULTS: A total of 17 retrospective trials were chosen for meta-analysis, including 1793 patients. The estimated pooled log HR (0.67, 95% CI: 0.57-0.77) of 9 trials (STAT3: log HR 0.71, 95% CI 0.38-1.04; phospho-STAT3: log HR 0.67, 95% CI 0.56-0.77) for NSCLC was statistically significant (P < 0.0001), suggesting that high STAT3 or phospho-STAT3 expression is a strong predictor of poor prognosis among patients with NSCLC. For the risk factors, pooled analysis of patients with STAT3 positivity, demonstrated a statistically significant OR (3.82, 95% CI: 2.37-6.16) between poorly differentiated carcinoma and well-moderately, OR (5.68, 95% CI: 3.16-10.21) between stage III-IV patients and stage I-II patients, and OR (3.41, 95% CI: 2.12-5.49) between patients with lymph node metastasis and patients without lymph node metastasis. However, pooled analysis of patients with phospho-STAT3 positivity only demonstrated a statistically significant OR (4.51, 95% CI: 1.57-12.96) between poorly differentiated carcinoma and well-moderately (P < 0.05). CONCLUSIONS: High STAT3 or phospho-STAT3 expression is a strong predictor of poor prognosis among patients with NSCLC. The conclusion should be confirmed by large prospective studies with long-term follow-up.

Identification of nuclear phosphoproteins as novel tobacco markers in mouse lung tissue following short-term exposure to tobacco smoke.

Smoking is a risk factor for lung diseases, including chronic obstructive pulmonary disease and lung cancer. However, the molecular mechanisms mediating the progression of these diseases remain unclear. Therefore, we sought to identify signaling pathways activated by tobacco-smoke exposure, by analyzing nuclear phosphoprotein expression using phosphoproteomic analysis of lung tissue from mice exposed to tobacco smoke. Sixteen mice were exposed to tobacco smoke for 1 or 7 days, and the expression of phosphorylated peptides was analyzed by mass spectrometry. A total of 253 phosphoproteins were identified, including FACT complex subunit SPT16 in the 1-day exposure group, keratin type 1 cytoskeletal 18 (K18), and adipocyte fatty acid-binding protein, in the 7-day exposure group, and peroxiredoxin-1 (OSF3) and spectrin ß chain brain 1 (SPTBN1), in both groups. Semi-quantitative analysis of the identified phosphoproteins revealed that 33 proteins were significantly differentially expressed between the control and exposed groups. The identified phosphoproteins were classified according to their biological functions. We found that the identified proteins were related to inflammation, regeneration, repair, proliferation, differentiation, morphogenesis, and response to stress and nicotine. In conclusion, we identified proteins, including OSF3 and SPTBN1, as candidate tobacco smoke-exposure markers; our results provide insights into the mechanisms of tobacco smoke-induced diseases.

Effects of acute intermittent hypoxia on energy balance and hypothalamic feeding pathways.

This study was done to investigate the effects of acute intermittent hypoxia (IH) on metabolic factors associated with energy balance and body weight, and on hypothalamic satiety-inducing pathways. Adult male Sprague-Dawley rats were exposed to either 8h IH or normoxic control conditions. Food intake, locomotion and body weights were examined after IH. Additionally, plasma levels of leptin, adiponectin corticosterone, insulin and blood glucose were measured following exposure to IH. Furthermore, adipose tissue was removed and analyzed for leptin and adiponectin content. Finally, the hypothalamic arcuate nucleus (ARC) was assessed for alterations in protein signaling associated with satiety. IH reduced body weight, food intake and active cycle locomotion without altering adipose tissue mass. Leptin protein content was reduced while adiponectin content was elevated in adipose tissue after IH. Plasma concentration of leptin was significantly increased while adiponectin decreased after IH. No changes were found in plasma corticosterone, insulin and blood glucose. In ARC, phosphorylation of signal transducer and activator of transcription-3 and pro-opiomelanocortin (POMC) expression were elevated. In addition, POMC-expressing neurons were activated as determined by immediate early gene FRA-1/2 expression. Finally, ERK1/2 and its phosphorylation were reduced in response to IH. These data suggest that IH induces significant alterations to body energy balance through changes in the secretion of leptin which exert effects on satiety-inducing pathways within the hypothalamus.

The U-box-type ubiquitin ligase PRP19ß regulates astrocyte differentiation via ubiquitination of PTP1B.

U-box protein PRP19ß, a splicing variant of PRP19α, suppresses neuronal differentiation and conversely promotes astrocyte differentiation as a neuron/glia switch molecule. However, the mechanistic basis of PRP19ß in astrocyte differentiation is not well understood. Here, we demonstrated that PRP19ß regulates the stability of protein tyrosine phosphatase 1B (PTP1B) via ubiquitination during N(6),2'-O-dibutyryl cyclic AMP (cAMP)-induced astrocyte differentiation of C6 cells. Only overexpression of PRP19ß conferred astrocyte properties at a certain level, and induced more astrocyte markers, glial fibrillary acidic protein (GFAP) and S100ß, in the presence of cAMP, whereas its down-regulation by antisense RNA showed a suppressive effect. In addition, ectopic expression of PRP19ß led to robust phosphorylation of signal transducer and activator of transcription 3 (STAT3) accompanying the reduction in PTP1B stability during astrocyte differentiation. Immunological analysis revealed that PRP19ß interacted with PTP1B and ubiquitinated PTP1B via its U-box region. Forced expression of the U-box deletion mutant of PRP19ß resulted in inhibition of astrocyte differentiation. Moreover, down-regulation of PTP1B by short hairpin (sh)RNA enhanced astrocyte differentiation, while forced expression of PTP1B showed an inhibitory effect. Thus, these results indicate that PRP19ß activates the gp130/Janus kinase (JAK)/STAT signaling pathway during astrocyte differentiation of C6 cells via PTP1B ubiquitination.