LIF maintains mouse embryonic stem cells pluripotency by modulating TET1 and JMJD2 activity in a JAK2-dependent manner.

The LIF-JAK2-STAT3 pathway is the central signal transducer that maintains undifferentiated mouse embryonic stem cells (mESCs), which is achieved by the recruitment of activated STAT3 to the master pluripotency genes and activation of the gene transcriptions. It remains unclear, however, how the epigenetic status required for the master gene transcriptions is built into LIF-treated mESC cultures. In this study, Jak2, but not Stat3, in the LIF canonical pathway, establishes an open epigenetic status in the pluripotency gene promoter regions. Upon LIF activation, cytosolic JAK2 was translocalized into the nucleus of mESCs, and reduced DNA methylation (5mC levels) along with increasing DNA hydroxymethylation (5hmC) in the pluripotent gene (Nanog/Pou5f1) promoter regions. In addition, the repressive histone codes H3K9m3/H3K27m3 were reduced by JAK2. Activated JAK2 directly interacted with the core epigenetic enzymes TET1 and JMJD2, modulating its activity and promotes the DNA and histone demethylation, respectively. The JAK2 effects were attained by tyrosine phosphorylation on the epigenetic enzymes. The effects of JAK2 phosphorylation on the enzymes were diverse, but all were merged to the epigenetic signatures associated with open DNA/chromatin structures. Taken together, these results reveal a previously unrecognized epigenetic regulatory role of JAK2 as an important mediator of mESC maintenance.

Atezolizumab and blockade of LncRNA PVT1 attenuate cisplatin resistant ovarian cancer cells progression synergistically via JAK2/STAT3/PD-L1 pathway.

OBJECTIVE: To investigate the relationship between lncRNA PVT1(PVT1) level and PD-L1 expression and their functions in cisplatin resistant epithelial ovarian cancer (CREOC). METHODS: PVT1 and PD-L1 in ovarian cancer tissues were detected and analyzed. The cells proliferation, apoptosis, invasion abilities and potential mechanism were detected by cell functional experiments and western-blot assay, respectively. RESULTS: The average expressions of PVT1 and PD-L1 in CREOC tissues were significantly higher. The expression of PVT1 is positively associated with PD-L1 in CREOC. Higher expressions of PVT1 and PD-L1 indicated more malignant clinical behavior and shorter PFS and OS. Knockdown of PVT1 inhibited the proliferation and invasion and promote apoptosis for A2780cis cells, which may be related to decrease the expression of PD-L1 via repressing JAK2/STAT3 pathway. CONCLUSIONS: The synergistic therapeutic strategy using LncRNA PVT1-targeted therapy and immune checkpoint blockade of PD-L1 warrant study further for ovarian cancer patients with cisplatin resistant recurrence.

Notoginsenoside R1 counteracts mesenchymal stem cell-evoked oncogenesis and doxorubicin resistance in osteosarcoma cells by blocking IL-6 secretion-induced JAK2/STAT3 signaling.

Tumor microenvironment is a critical participant in the initiation, progression and drug resistance of carcinomas, including osteosarcoma. Notoginsenoside R1 (NGR1) is a proverbial active ingredient of the traditional Chinese medicine Panax notoginseng (PN) and possess undeniable roles in several cancers. Nevertheless, its function in osteosarcoma and tumor microenvironment remains elusive. In the current study, exposure to NGR1 dose-dependently inhibited osteosarcoma cell viability and migration, and induced apoptosis. Furthermore, osteosarcoma cells that were incubated with conditioned medium (CM) from bone marrow mesenchymal stem cells (BMSCs) exhibited greater proliferation, migration capacity and MMP-2 and MMP-9 expression relative to control cells, which was reversed when BMSCs were treated with NGR1. Notably, administration with NGR1 antagonized CM-evoked doxorubicin resistance in osteosarcoma cells by decreasing cell viability and increasing cell apoptosis and caspase-3/9 activity. Mechanically, NGR1 suppressed IL-6 secretion from BMSCs, as well as the subsequent activation of the JAK2/STAT3 signaling in osteosarcoma cells. In addition, blocking the JAK2 pathway by its antagonist AG490 reversed CM-induced osteosarcoma cell proliferation, migration and doxorubicin resistance. Moreover, exogenous supplementation with IL-6 engendered not only the reactivation of the JAK2/STAT3 signaling but also muted NGR1-mediated efficacy against osteosarcoma cell malignancy and doxorubicin resistance. Collectively, NGR1 may directly restrain osteosarcoma cell growth and migration, or indirectly antagonize MSC-evoked malignancy and drug resistance by interdicting IL-6 secretion-evoked activation of the JAK2/STAT3 pathway. Consequently, the current study may highlight a promising therapeutic strategy against osteosarcoma by regulating tumor cells and the tumor microenvironment.

Cucurbitacin B exhibits antitumor effects on CD133+ HepG2 liver cancer stem cells by inhibiting JAK2/STAT3 signaling pathway.

Cancer stem cells (CSCs), a crucial cancer cell subpopulation, possess stemness phenotypic characteristics. Cucurbitacin B (CuB), a tetracyclic triterpenoid isolated from Cucurbitaceae, exerts widely pharmacological activities in many diseases. The aim of this study was to enrich, identify liver CSCs and investigate antitumor effects of CuB as well as explore the underlying molecular mechanisms in these liver CSCs. HepG2 cell lines were used for the enrichment of liver CSCs by serum-free medium culture and magnetic-activated cell sorting. The CSC characteristics were analyzed by immunofluorescent staining, sphere-forming, western blot and xenograft tumorigenicity assay. CuB' antitumor effects and underlying molecular mechanism were measured by cell counting kit-8, colony formation, sphere-forming, cell cycle, xenograft and western blot assay. Our results showed that we could enrich 97.29% CD133+ HepG2 cells, which possessed CSC characteristics including re-renewal capacity, proliferative ability, sorafenib resistance, overexpressed stemness-related molecules and enhanced tumorigenic potential. Furthermore, we also found that CuB inhibited cell viability, sphere formation, colony formation and arrested cell cycle at G2/M phase as well as sensitized CD133+ HepG2 cells to sorafenib in vitro and in vivo. Western blot assay indicated that CuB inhibited expression levels of cyclin B1, CDK1, CD133, p-JAK2 and p-STAT3. In conclusion, our findings indicated that CuB could exhibit antitumor effects on CD133+ HepG2 CSCs by inhibiting the Janus kinase 2/signal transducers and activators of transcription-3 signaling pathway, expanding basic and preclinical investigations on liver CSCs.

Levetiracetam Reduces Early Inflammatory Response After Experimental Intracerebral Hemorrhage by Regulating the Janus Kinase 2 (JAK2)-Signal Transducer and Activator of Transcription 3 (STAT3) Signaling Pathway.

BACKGROUND Levetiracetam (LEV) is an antiepileptic drug that promotes recovery of neurological function by alleviating inflammatory reactions. However, it is not known whether it can improve secondary brain injury after intracerebral hemorrhage (ICH). The aim of this study was to determine whether LEV can reduce early inflammatory response after ICH in rats. MATERIAL AND METHODS An in vitro model of early inflammation was created by treating microglia cells with lipopolysaccharide (LPS). After exposure to various concentrations of LEV, the expression levels of NF-kappaB and STAT3 and inflammatory factors such as interleukin (IL)-1ß and tumor necrosis factor (TNF)-alpha in microglia were detected. In vivo, autologous blood was used to induce the rat ICH model. The effects of LEV on post-cerebral hemorrhagic inflammatory response were examined using neurobehavioral tests, FJC staining, brain water content testing, and analysis of protein expression levels of NF-kappaB, JAK2, STAT3, and inflammatory factors. RESULTS LEV treatment significantly reduced the expression of inflammatory factors and protein expression levels of NF-kappaB and STAT3 in LPS-treated microglia cells (P<0.05). In male Sprague-Dawley (SD) rats, LEV treatment markedly decreased the volume of hematoma and the number of degenerative neurons (P<0.05). It also improved the neurological function and relieved brain edema. The protein expression levels of NF-kappaB, JAK2, and STAT3 were significantly lower in the ICH+LEV group than in the control group (P<0.05). CONCLUSIONS Our study suggests that treatment with LEV alleviates early inflammatory responses induced by ICH. Mechanistically, LEV inhibited the JAK2-STAT3 signaling pathway and reduced neuronal injury around the hematoma, and ameliorated brain edema, all of which promoted recovery of nerve function after hemorrhage.

The inhibition of the breast cancer by PPARγ agonist pioglitazone through JAK2/STAT3 pathway.

Breast cancer, especially triple-negative breast cancer, is one of the deadliest cancers in women. To date, there is a lack of a good therapeutic regimen for it. PPARγ has been reported to be a tumor suppressor and could be activated by many agonists involved in cancer inhibition. Therefore, the expression of PPARγ in breast cancer was analyzed by online software UALCAN whose data were from the TCGA database. The results revealed that the PPARγ expression was reduced in breast cancer tissues. Furthermore, the methylation in the PPARγ promoter was also assayed and the results indicated that the methylation level in the PPARγ promoter in breast cancer tissue was higher than that in normal tissue. In order to verify the methylation in promoter involved in the regulation of gene PPARγ expression, the 5'-Aza and fluorescence assays were performed and the results proved that methylation in promoter participated in gene PPARγ expression regulation. Pioglitazone, a PPARγ agonist, still was not investigated in breast cancer. Therefore, the effects of pioglitazone on breast cancer cells were tested by cell viability, scratch and transwell assays, and results indicated that the pioglitazone has the inhibition effect on the proliferation and migration of breast cancer cells by PPARγ which was correlated with the JAK2/STAT3 pathway. In order to further confirm the inhibition effect of pioglitazone on breast cancer in vivo, the nude mice model was administrated by gavage with pioglitazone. And the results indicated that pioglitazone could inhibit the growth of breast cancer in the PPARγ overexpression group in vivo. In summary, the expression of gene PPARγ was decreased in breast cancer tissues, which was correlated with its methylation in the promoter region. Moreover, pioglitazone could exert its inhibition on breast cancer proliferation and migration by the JAK2/STAT3 pathway.

JAK2/STAT3 involves oxidative stress-induced cell injury in N2a cells and a rat MCAO model.

Purpose: In this study, we sought to test the hypothesis that oxidative stress injury in ischemic brains and H2O2-treated mouse neuroblastoma Neuro-2a cells (N2a) was related to STAT3 activation.Materials and methods: Rat middle cerebral artery occlusion (MCAO) model and H2O2-treated mouse neuroblastoma Neuro-2a cells (N2a) were used to investigate the relationship between oxidative stress injury and STAT3 activation.Results: 8-Hydroxy-2'-deoxyguanosine (8-OHdG) content and STAT3 protein phosphorylation level were significantly increased after cerebral ischemia-reperfusion. H2O2 treatment inhibited the cell viability, induced the apoptosis, and further raised pSTAT3 protein level in N2a cells. Moreover, the addition of AG490, the protein inhibitor of JAK2, significantly alleviated cerebral ischemic damage in vivo and H2O2-induced injury in vitro, and JAK2 siRNA also alleviated H2O2-induced injury in N2a cell.Conclusions: JAK2/STAT3 pathway may play a crucial role in mediating reactive oxidative species (ROS)-induced cell injury in rat middle cerebral artery occlusion (MCAO) model and N2a cells. ROS scavenging and down-regulation of STAT3 activation might be a candidate design of therapeutic strategies against oxidative stress-related neurological diseases.

Activation of peroxisome proliferator-activated receptor delta suppresses BACE1 expression by up-regulating SOCS1 in a JAK2/STAT1-dependent manner.

Neuronal expression of beta-secretase 1 (BACE1) has been implicated in the progression of Alzheimer's disease. However, the mechanisms that regulate BACE1 expression are unclear. Here, we show that peroxisome proliferator-activated receptor delta (PPARδ) decreases BACE1 expression by up-regulating suppressor of cytokine signaling 1 (SOCS1) in SH-SY5Y neuroblastoma cells. The activation of PPARδ by GW501516, a specific PPARδ agonist, inhibited expression of BACE1. This effect was abrogated by shRNA-mediated knockdown of PPARδ and by treatment with the PPARδ antagonist GSK0660, indicating that PPARδ is involved in GW501516-mediated suppression of BACE1 expression. On the other hand, GW501516-activated PPARδ induced expression of SOCS1, which is a negative regulator of cytokine signal transduction, at the transcriptional level by binding to a PPAR response element in its promoter. This GW501516-mediated induction of SOCS1 expression led to down-regulation of BACE1 expression via inactivation of signal transducer and activator of transcription 1. GW501516-activated PPARδ suppressed the generation of neurotoxic amyloid beta (Aß) in accordance with the decrease in BACE1 expression. Taken together, these results indicate that PPARδ attenuates BACE1 expression via SOCS1-mediated inhibition of signal transducer and activator of transcription 1 signaling, thereby suppressing BACE1-associated generation of neurotoxic Aß.

Expression of pro-inflammatory cytokines and mediators induced by Bisphenol A via ERK-NFκB and JAK1/2-STAT3 pathways in macrophages.

Macrophages not only play an important role in the innate immune response but also participate in many inflammatory and infectious diseases including asthma, diabetes, obesity, cardiovascular diseases, and cancers. Bisphenol A (BPA) is the most commonly used component for plastic products. However, BPA is an endocrine disruptor for mammals and participates in several inflammatory and infectious diseases. Up until now, there are no researches demonstrated the potential role of BPA in macrophage activation and its relative mechanism. BPA promoted the generation of proinflammatory cytokines IL-1ß, IL-6, and TNFα in a concentration-dependent manner (P < 0.05). BPA was identified to increase the expression of proinflammatory mediators NO and PGE2, and its upstream factors iNOS, COX2, and cPLA2 in a concentration-dependent manner (P < 0.05). Phosphorylation and nuclear translocation of NF-κB p65 were significantly induced by BPA via IκB degradation (P < 0.05). In addition, phosphorylation of ERK significantly induced by BPA at a concentration which was less than that for phosphorylation of p38 MAPK and JNK (P < 0.05). Furthermore, phosphorylation of STAT3 significantly induced by BPA at a concentration lower than that for phosphorylation of STAT1 (P < 0.05). Phosphorylation of JAK1 and JAK2 was also significantly induced by BPA in a concentration-dependent manner (P < 0.05).

Zeylenone inhibits proliferation and promotes apoptosis in ovarian carcinoma cells via Janus kinase 2 / signal transducers and activators of transcription 3 pathways.

AIM: Ovarian cancer is the fifth common cancer in females. The aim of our study was to determine function of Zeylenone on cell viability and apoptosis of ovarian carcinoma SKOV3 cells. METHODS: Cell viability was measured by Cell counting kit-8 (CCK8) assay; Mitochondrial membrane potential (MMP) and apoptosis were detected by flow cytometry. The mRNA and protein levels of related factors were determined by Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot, respectively. RESULTS: Cell viability was decreased by Zeylenone in a dose-dependent manner. Zeylenone with concentrations of 2.5, 5 and 10 µmol/L was used to treat ovarian carcinoma SKOV3 cells for 24 h in the following study. The loss of MMP and apoptosis were both significantly increased by Zeylenone. The mRNA and protein levels of cytochrome c (cyto c) and apoptosis inducing factor (AIF) in cytosol were increased by Zeylenone. The mRNA and protein levels of Caspase-3, Fas, Fasl and Bax were increased; while the expression of Bcl-2 was decreased by Zeylenone. The expression of (Janus family of tyrosine kinase) p-JAK and signal transducer and activator of transcription (p-STAT) was decreased significantly by Zeylenone. CONCLUSION: Zeylenone inhibited cell proliferation and promoted apoptosis in ovarian carcinoma cells. The JAK-STAT pathway was involved in this progress.

JAK1-dependent transphosphorylation of JAK2 limits the antifibrotic effects of selective JAK2 inhibitors on long-term treatment.

OBJECTIVES: Janus kinase 2 (JAK2) has recently been described as a novel downstream mediator of the pro-fibrotic effects of transforming growth factor-ß. Although JAK2 inhibitors are in clinical use for myelodysplastic syndromes, patients often rapidly develop resistance. Tumour cells can escape the therapeutic effects of selective JAK2 inhibitors by mutation-independent transactivation of JAK2 by JAK1. Here, we used selective JAK2 inhibition as a model to test the hypothesis that chronic treatment may provoke resistance by facilitating non-physiological signalling pathways in fibroblasts. METHODS: The antifibrotic effects of long-term treatment with selective JAK2 inhibitors and reactivation of JAK2 signalling by JAK1-dependent transphosphorylation was analysed in cultured fibroblasts and experimental dermal and pulmonary fibrosis. Combined JAK1/JAK2 inhibition and co-treatment with an HSP90 inhibitor were evaluated as strategies to overcome resistance. RESULTS: The antifibrotic effects of selective JAK2 inhibitors on fibroblasts decreased with prolonged treatment as JAK2 signalling was reactivated by JAK1-dependent transphosphorylation of JAK2. This reactivation could be prevented by HSP90 inhibition, which destabilised JAK2 protein, or with combined JAK1/JAK2 inhibitors. Treatment with combined JAK1/JAK2 inhibitors or with JAK2 inhibitors in combination with HSP90 inhibitors was more effective than monotherapy with JAK2 inhibitors in bleomycin-induced pulmonary fibrosis and in adTBR-induced dermal fibrosis. CONCLUSION: Fibroblasts can develop resistance to chronic treatment with JAK2 inhibitors by induction of non-physiological JAK1-dependent transactivation of JAK2 and that inhibition of this compensatory signalling pathway, for example, by co-inhibition of JAK1 or HSP90 is important to maintain the antifibrotic effects of JAK2 inhibition with long-term treatment.

[Protective effect of diosgenin on chondrocytes mediated by JAK2/STAT3 signaling pathway in mice with osteoarthritis].

Objective: To investigate the effect of diosgenin (Dgn) on chondrocytes and its relation to JAK2/STAT3 signaling pathway in mice with osteoarthritis (OA).Methods: Fifteen male C57BL/6 mice were randomly divided into three groups:control group, OA group and OA+Dgn group. After 4 weeks of treatment, the histopathological changes of cartilage tissue were observed by toluidine blue staining under light microscopy and the ultrastructure of chondrocytes was observed under electron microscopy. The primarily cultured chondrocytes of OA mice were randomly divided into 4 groups:(1) OA group, (2) Dgn group, (3) Dgn+AG490 group, (4) AG490 group. The expression of p-JAK2, p-STAT3, Bax, succinate dehydrogenase (SDH) and cytochrome c oxidase (COX) were detected by Western blotting, and superoxide dismutase (SOD) was detected using colorimetric method. Results: The morphological observation showed that the chondrocytes of OA group presented considerable pathological changes, while the chondrocytes in OA+Dgn group maintained intact membrane. Electron microscopy observation found obvious injury in cartilage tissues of OA group, while that in OA+Dgn group remained smooth. Compared with OA group, the expressions of p-JAK2 and p-STAT3 in chondrocytes of Dgn group were increased (all P<0.05), and the expressions of Bax protein, SDH, COX and SOD were decreased (all P<0.05). While compared with Dgn group, the expressions of p-JAK2, p-STAT3, SDH, COX and SOD in chondrocytes of Dgn+AG490 group were decreased (all P<0.05), and the expression of Bax protein was increased (P<0.05). Conclusion: Diosgenin can inhibit apoptosis and increase mitochondrial oxidative stress capacity of chondrocytes in mice with osteoarthritis, which is closely related to the activation of JAK2/STAT3 signaling pathway.

[Effect and its molecular mechanisms of curcumin on pulmonary artery smooth muscle cells in rat model with chronic obstructive pulmonary disease].

Objective: To investigate the effects and the underlying molecular mechanisms of curcumin on pulmonary artery smooth muscle cells in rat model with chronic obstructive pulmonary disease (COPD). Methods: A total of 75 male Wistar rats were randomly divided into control group (group CN), model group (group M), low-dose curcumin group (group CL), medium-dose curcumin group (group CM) and high-dose curcumin group (group CH). HE staining was used to observe the morphology of pulmonary artery. Proliferating cell nuclear antigen (PCNA), apoptosis-related protein Bcl-2 and Bax were detected by immunohistochemical staining. TUNEL kit was used to analyze the effects of curcumin on apoptosis of smooth muscle cells, and the protein expressions of SOCS-3/JAK2/STAT pathway in lung tissues were determined by western blot. Results: Right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVMI) in group M were significantly higher than those in group CN, group CH and group CM (all P<0.05). HE staining and TUNEL kit test showed that the number of pulmonary artery smooth muscle cells had a significant increase in group M, while the pulmonary artery tube became thin, and the smooth muscle cells shrinked in group CM and group CH. Immunohistochemistry showed that PCNA and Bcl-2 in group M were significantly higher than those in group CN (all P<0.05), while Bax expression was significantly lower than that in group CN (P<0.05). PCNA in group CM and group CH were significantly lower than that in group M (all P<0.05), while Bax expression was significantly higher than that in group M (P<0.05). Western blot showed that SOCS-3 protein was significantly decreased in group M, while the p-JAK2, p-STAT1, p-STAT3 were significantly increased (all P<0.05). Compared with group M, SOCS-3 protein in group CM and group CH were significantly increased (all P<0.05), while the p-JAK2, p-STAT3 were significantly reduced (all P<0.05). Conclusion: Curcumin could promote the apoptosis of smooth muscle cells in rats with COPD, and improve the mean pulmonary artery pressure and RVMI through stimulating SOCS-3/JAK2/STAT signaling pathway.

Inhibition of casein kinase II reduces TGFß induced fibroblast activation and ameliorates experimental fibrosis.

OBJECTIVES: Casein kinase II (CK2) is a constitutively active serine/threonine protein kinase that plays a key role in cellular transformation and tumorigenesis. The purpose of the study was to characterise whether CK2 contributes to the pathologic activation of fibroblasts in patients with SSc and to evaluate the antifibrotic potential of CK2 inhibition. METHODS: Activation of CK2, JAK2 and STAT3 in human skin and in experimental fibrosis was analysed by immunohistochemistry. CK2 signalling was inhibited by the selective CK2 inhibitor 4, 5, 6, 7-Tetrabromobenzotriazole (TBB). The mouse models of bleomycin-induced and TGFß receptor I (TBR)-induced dermal fibrosis were used to evaluate the antifibrotic potential of specific CK2 inhibition in vivo. RESULT: Increased expression of CK2 was detected in skin fibroblasts of SSc patients. Inhibition of CK2 by TBB abrogated the TGFß-induced activation of JAK2/STAT3 signalling and prevented the stimulatory effects of TGFß on collagen release and myofibroblasts differentiation in cultured fibroblasts. Inhibition of CK2 prevented bleomycin-induced and TBR-induced skin fibrosis with decreased dermal thickening, lower myofibroblast counts and reduced accumulation of collagen. Treatment with TBB also induced regression of pre-established fibrosis. The antifibrotic effects of TBB were accompanied by reduced activation of JAK2/STAT3 signalling in vivo. CONCLUSIONS: We provide evidence that CK2 is activated in SSc and contributes to fibroblast activation by regulating JAK2/STAT3 signalling. Inhibition of CK2 reduced the pro-fibrotic effects of TGFß and inhibited experimental fibrosis. Targeting of CK2 may thus be a novel therapeutic approach for SSc and other fibrotic diseases.

[Tanshinone attenuates myocardial injury via activating JAK2/STAT1 pathway in a murine model of viral myocarditis].

OBJECTIVE: To explore the effects of tanshinone and JAK2/STAT1 signaling pathway related mechanism in CVB3-induced myocarditis in murine. METHODS: A total of 110 inbred male Balb/c mice which were 4 to 6 weeks-old were randomly divided into five groups: normal control (N, n = 10), myocarditis control (C, n = 25), tanshinone group (T, 15 mg · kg⁻¹ · d⁻¹, i.p., n = 25), janus kinase 2 inhibitor AG490 group (A, 10 mg · kg⁻¹ · d⁻¹, i.p., n = 25), T+A group (H, n = 25). Myocarditis was induced by 0.5 ml 10(-9.51) TCID50/ml CVB3 i.p. injection for 10 days in group C, T and H. Myocardial histopathologic changes were observed and phospho-STAT1 expressions were detected by immunohistochemistry and Western blot analysis. The levels of serum cardiac troponin I were detected with chemiluminescence immunoassay. RESULTS: (1) Compared with group C, the histopathologic scores were significantly higher in group A and H (3.35 ± 0.57 and 3.34 ± 0.54 vs. 2.12 ± 0.39, P < 0.01), but lower in group T (1.40 ± 0.34 vs.2.12 ± 0.39, P < 0.01). (2) The expression of p-STAT1 protein was similar in group A and H compared to group N (P > 0.05), but was significantly lower than that in group C (0.017 ± 0.010 and 0.020 ± 0.010 vs. 0.246 ± 0.010, P < 0.01). The expression of p-STAT1 protein was significantly higher in group T than in group C (P < 0.01). (3) The levels of serum cardiac troponin I in group C, A, T and H were significantly higher than in group N ((0.42 ± 0.06), (1.17 ± 0.25), (0.23 ± 0.05) and (1.04 ± 0.19) µg/L vs. (0.02 ± 0.01) µg/L, all P < 0.01). The levels of serum cardiac troponin I were significantly higher in group A and H compared with group C ((1.17 ± 0.25) and (1.04 ± 0.19) µg/L vs. (0.42 ± 0.06) µg/L, P < 0.01), but were significantly lower in group T than in group C ((0.23 ± 0.05) µg/L vs. (0.42 ± 0.06) µg/L, P < 0.01). (4) There was a negative correlation between the expression level of p-STAT1 and the histopathologic scores (y = -4.503 x + 3.371, R² = 0.738, P < 0.01), but a positive correlation between the levels of serum cardiac troponin I and the histopathologic scores (y = 1.935x + 1.165, R² = 0.766, P < 0.01). CONCLUSION: Tanshinone could attenuate myocardial injury via upregulating the JAK2/STAT1 signaling pathway in this murine viral myocarditis model.

Loss of Jak2 impairs endothelial function by attenuating Raf-1/MEK1/Sp-1 signaling along with altered eNOS activities.

A number of inhibitors have been used to dissect the functional relevance of Jak2 in endothelial homeostasis, with disparate results. Given that Jak2 deficiency leads to embryonic lethality, the exact role of Jak2 in the regulation of postnatal endothelial function is yet to be fully elucidated. We generated a model in which Jak2 deficiency can be induced by tamoxifen in adult mice. Loss of Jak2 significantly impaired endothelium-dependent response capacity for vasodilators. Matrigel plug assays indicated a notable decrease in endothelial angiogenic function in Jak2-deficient mice. Studies in a hindlimb ischemic model indicated that Jak2 activity is likely to be a prerequisite for prompt perfusion recovery, based on the concordance of temporal changes in Jak2 expression during the course of ischemic injury and perfusion recovery. A remarkable delay in perfusion recovery, along with reduced capillary and arteriole formation, was observed in Jak2-deficient mice. Antibody array studies indicated that loss of Jak2 led to repressed eNOS expression. In mechanistic studies, Jak2 deficiency attenuated Raf-1/MEK1 signaling, which then reduced activity of Sp-1, an essential transcription factor responsible for eNOS expression. These data are important not only for understanding the exact role that Jak2 plays in endothelial homeostasis, but also for assessing Jak2-based therapeutic strategies in a variety of clinical settings.

Loganin protects against myocardial ischemia-reperfusion injury by modulating oxidative stress and cellular apoptosis via activation of JAK2/STAT3 signaling.

BACKGROUND: Myocardial ischemia-reperfusion injury (MIRI) is a pathological process that follows immediate revascularization of myocardial infarction and is characterized by exacerbation of cardiac injury. Loganin, a monoterpene iridoid glycoside derived from Cornus officinalis Sieb. Et Zucc, can exert cardioprotective effects in cardiac hypertrophy and atherosclerosis. However, its role in ischemic heart disease remains largely unknown. METHODS: Considering that Janus kinase 2 (JAK2)/ signal transducer and activator of transcription 3 (STAT3) has a protective effect on the heart, we developed a mouse model of MIRI to investigate the potential role of this pathway in loganin-induced cardioprotection. RESULTS: Our results showed that treatment with loganin (20 mg/kg) prevented the enlargement of myocardial infarction, myocyte destruction, serum markers of cardiac injury, and deterioration of cardiac function induced by MIRI. Myocardium subjected to I/R treatment exhibited higher levels of oxidative stress, as indicated by an increase in malondialdehyde (MDA) and dihydroethidium (DHE) density and a decrease in total antioxidant capacity (T-AOC), glutathione (GSH), and superoxide dismutase (SOD), whereas treatment with loganin showed significant attenuation of I/R-induced oxidative stress. Loganin treatment also increased the expression of anti-apoptotic Bcl-2 and reduced the expression of caspase-3/9, Bax, and the number of TUNEL-positive cells in ischemic cardiac tissue. Moreover, treatment with loganin triggered JAK2/STAT3 phosphorylation, and AG490, a JAK2/STAT3 inhibitor, partially abrogated the cardioprotective effects of loganin, indicating the essential role of JAK2/STAT3 signaling in the cardioprotective effects of loganin. CONCLUSIONS: Our data demonstrate that loganin protects the heart from I/R injury by inhibiting I/R-induced oxidative stress and cellular apoptosis via activation of JAK2/STAT3 signaling.

Anti-inflammatory effects of reticuline on the JAK2/STAT3/SOCS3 and p38 MAPK/NF-κB signaling pathway in a mouse model of obesity-associated asthma.

BACKGROUND: Asthma associated with obesity is a chronic disease characterized by earlier airway remodeling, severe wheezing, and increased insensitivity to hormone therapy. Reticuline, a bioactive compound of Magnoliae Flos, exerts anti-inflammatory activity and can inhibit neutrophil recruitment. Thus, this study investigated the role of reticuline in obesity-related asthma. METHODS: The BALB/c mice fed a low-fat diet (LFD) and high-fat diet (HFD) were intranasally challenged with house dust mites (HDMs) or ovalbumin (OVA). Reticuline (0.25 mg/kg) was administrated into mice by intragastrical gavage. Airway hyper-responsiveness was examined after the final challenge. Body weight was measured, and bronchoalveolar lavage fluid (BALF) and lung tissues were collected. The number of inflammatory cells in BALF was estimated. Histological changes were assessed by performing hematoxylin-eosin staining, and production of proinflammatory cytokines and IgE was examined by ELISA kits. Related pathways were studied with western blotting. RESULTS: Reticuline suppressed airway resistance and inflammatory infiltration in lung tissue and reduced inflammatory cell recruitment in BALF in obesity mice with asthma. Additionally, the levels of IL-17A, IL-1ß, IL-5, macrophage inflammatory protein 2, and regulated on activation, normal T cell expressed and secreted in the lung were reduced by reticuline. Mechanistically, reticuline inactivated the JAK2/STAT3/SOCS3 and p38 MAPK/NF-κB signaling pathways in obesity-related asthma. CONCLUSION: Reticuline alleviates airway inflammation in obesity-related asthma by inactivating the JAK2/STAT3/SOCS3 and p38 MAPK/NF-κB signaling pathways.

Quercetin exerts anti-tumor immune mechanism by regulating IL-6/JAK2/STAT3 signaling pathway to deplete Treg cells.

Breast cancer is still the leading cause of death among women worldwide. Due to the lack of effective drug targets, triple-negative breast cancer has a worse prognosis and higher mortality compared with other types of breast cancer, and chemotherapy is still the main treatment for triple-negative breast cancer at present. Quercetin (QUE) is a flavonoid compound found in a variety of fruits and vegetables. The mechanism of QUE has been extensively studied, such as prostate cancer, colon cancer, ovarian cancer, etc. However, the anti-tumor immune mechanism of QUE in triple-negative breast cancer remains unclear. Therefore, we assessed the anti-tumor immune effects of QUE on triple-negative breast cancer using both 4T1 cells and a xenograft mouse model of 4T1 cells. In vitro, we examined the inhibitory effects of QUE on 4T1 cells and its molecular mechanisms through MTT, Transwell, ELISA, and Western blotting. In vivo, by establishing a xenograft mouse model, we utilized flow cytometry, immunohistochemistry, ELISA, and Western blotting to evaluate the anti-tumor immune effects of QUE on triple-negative breast cancer. The results indicate that QUE inhibits the proliferation, migration, and invasion of 4T1 cells, concurrently significantly suppressing the IL-6/JAK2/STAT3 signaling pathway. Furthermore, it depletes Treg cell content in 4T1 xenograft mice, thereby improving the tumor immune microenvironment and promoting the cytotoxicity of relevant tumor immune cells. These findings suggest that QUE may serve as a potential adjuvant for immune therapy in triple-negative breast cancer.