The improved anticancer effects of Bortezomib-loaded hollow mesoporous silica nanospheres on lymphoma development.

As the first clinical proteasome inhibitor, Bortezomib (BTZ) has been reported to improve the outcome of lymphoma. However, due to the unstable property, low bioavailability, and hydrophobic properties of BTZ, it is needed to develop effective drug delivery systems to deliver BTZ into targeted cells or organs. Here we developed a bortezomib (BTZ)-loaded HMSNs (BTZ@HMSNs) system, which can sustain the release of BTZ in targeted tissues. In vitro assays showed that BTZ@HMSNs limited cell proliferation and augmented apoptosis of lymphoma SNK-1 cells. Moreover, BTZ@HMSNs significantly diminished migration and invasion of SNK-1 cells as compared with BTZ. In contrast to the upregulation of SHP-1, BTZ@HMSNs decreased the mRNA levels of c-Kit, NF-κB, and JAK1, which elicit oncogenic role in lymphoma development. Importantly, lymphoma mice model showed that BTZ@HMSNs significantly activated p53 signaling and reduced tumor volume and weight compared with free BTZ. Our data thus demonstrate that BTZ@HMSNs manifests improved tumor-suppressing effect in vitro and in vivo compared to free BTZ. We believe that HMSNs is a promising strategy for delivering therapeutic agents for cancer treatment.

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).

JAK1/3 inhibition preserves epidermal morphology in full-thickness 3D skin models of atopic dermatitis and psoriasis.

BACKGROUND: Janus kinase (JAK) inhibition may be a promising new treatment modality for inflammatory (skin) diseases. However, little is known about direct effects of kinase inhibitors on keratinocyte differentiation and function as well as skin barrier formation. OBJECTIVE: Our aim was to address the direct impact of kinase inhibition of the JAK1/3 pathways by tofacitinib on keratinocyte immune function and barrier formation in atopic dermatitis (AD) and psoriasis. METHODS: 3D skin equivalents of both diseases were developed and concurrently pretreated with tofacitinib. To induce AD, 3D skin equivalents were stimulated with recombinant human IL-4 and IL-13. Psoriasis-like conditions were induced by incubation with IL-17A, IL-22 and tumour necrosis factor α (TNFα). The activation of signal transducer and activator of transcription (STAT)1, STAT3 and STAT6 was assessed by Western blot analysis. Microarray analysis and quantitative real-time PCR were used for gene expression analysis. RESULTS: Tofacitinib pretreatment preserved epidermal morphology and reduced STAT3 and STAT6 phosphorylation of AD-like and STAT3 phosphorylation of psoriasis-like culture conditions in 3D skin models compared to sham-controls. Filaggrin expression was fully maintained in the AD-like models, but only partially in psoriasis-like conditions after pretreatment with tofacitinib. In addition, tofacitinib upregulated DSC1, FLG and KRT1. Using gene expression analysis, downregulation of POSTN and IL24 was observed in AD-like conditions, whereas downregulation of IL20 and IL1B was observed in psoriasis-like conditions. CONCLUSION: JAK1/3 inhibition counteracted cytokine-induced AD- and psoriasis-like epidermal morphology and enhanced keratinocyte differentiation in 3D skin models. This effect was more pronounced in the AD-like models compared to the psoriasis-like 3D skin models.

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.

Recombinant human brain natriuretic peptide ameliorates trauma-induced acute lung injury via inhibiting JAK/STAT signaling pathway in rats.

BACKGROUND: JAK/STAT signal pathway plays an important role in the inflammation process of acute lung injury (ALI). This study aimed to investigate the correlation between recombinant human brain natriuretic peptide (rhBNP) and the JAK/STAT signaling pathway and to explore the protective mechanism of rhBNP against trauma-induced ALI. METHODS: The arterial partial pressure in oxygen, lung wet-dry weight ratios, protein content in bronchoalveolar lavage fluid, the histopathologic of the lung, as well as the protein expressions of STAT1, JAK2, and STAT3 were detected. RESULTS: Sprague-Dawley rats were randomly divided into five groups: a control group, a sham-operated group, an ALI group, an ALI + rhBNP group, and an ALI + AG490 group. At 4 hours, 12 hours, 1 day, 3 days, and 7 days after injury, injured lung specimens were harvested. rhBNP pretreatment significantly ameliorated hypoxemia and histopathologic changes and alleviated pulmonary edema in trauma-induced ALI rats. rhBNP pretreatment reduced the phosphorylated protein and total protein level of STAT1. Similarly to JAK-specific inhibitor AG490, rhBNP was shown to significantly inhibit the phosphorylation of JAK2 and STAT3 in rats with trauma-induced ALI. CONCLUSION: Our experimental findings indicated that rhBNP can protect rats against trauma-induced ALI and that its underlying mechanism may be related to the inhibition of JAK/STAT signaling pathway activation.

The JAK inhibitor tofacitinib suppresses synovial JAK1-STAT signalling in rheumatoid arthritis.

OBJECTIVE: Tofacitinib is an oral Janus kinase (JAK) inhibitor for the treatment of rheumatoid arthritis (RA). The pathways affected by tofacitinib and the effects on gene expression in situ are unknown. Therefore, tofacitinib effects on synovial pathobiology were investigated. METHODS: A randomised, double-blind, phase II serial synovial biopsy study (A3921073; NCT00976599) in patients with RA with an inadequate methotrexate response. Patients on background methotrexate received tofacitinib 10 mg twice daily or placebo for 28 days. Synovial biopsies were performed on Days -7 and 28 and analysed by immunoassay or quantitative PCR. Clinical response was determined by disease activity score and European League Against Rheumatism (EULAR) response on Day 28 in A3921073, and at Month 3 in a long-term extension study (A3921024; NCT00413699). RESULTS: Tofacitinib exposure led to EULAR moderate to good responses (11/14 patients), while placebo was ineffective (1/14 patients) on Day 28. Tofacitinib treatment significantly reduced synovial mRNA expression of matrix metalloproteinase (MMP)-1 and MMP-3 (p<0.05) and chemokines CCL2, CXCL10 and CXCL13 (p<0.05). No overall changes were observed in synovial inflammation score or the presence of T cells, B cells or macrophages. Changes in synovial phosphorylation of signal transducer and activator of transcription 1 (STAT1) and STAT3 strongly correlated with 4-month clinical responses (p<0.002). Tofacitinib significantly decreased plasma CXCL10 (p<0.005) at Day 28 compared with placebo. CONCLUSIONS: Tofacitinib reduces metalloproteinase and interferon-regulated gene expression in rheumatoid synovium, and clinical improvement correlates with reductions in STAT1 and STAT3 phosphorylation. JAK1-mediated interferon and interleukin-6 signalling likely play a key role in the synovial response. TRIAL REGISTRATION NUMBER: NCT00976599.

Interleukin-1beta-induced iNOS expression in human lung carcinoma A549 cells: involvement of STAT and MAPK pathways.

For understanding of signaling molecules important in lung cancer growth and progression, IL-1beta effect was analyzed on iNOS expression and key signaling molecules in human lung carcinoma A549 cells and established the role of specific signaling molecules by using specific chemical inhibitors. IL-1beta exposure (10 ng/ml) induced strong iNOS expression in serum starved A549 cells. Detailed molecular analyses showed that IL-1beta increased expression of phosphorylated STAT1 (Tyr701 and Ser727) and STAT3 (Tyr705 and Ser727) both in total cell lysates and nuclear lysates. Further, IL-1beta exposure strongly activated MAPKs (ERK1/2, JNK1/2 and p38) and Akt as well as increased nuclear levels of NF-kappaB and HIF-1alpha in A549 cells. Use of specific chemical inhibitors for JAK1 kinase (piceatannol), JAK2 kinase (AG-490), MEK1/2 (PD98059) and JNK1/2 (SP600125) revealed that IL-1beta-induced iNOS expression involved signaling pathways in addition to JAK-STAT and ERK1/2-JNK1/2 activation. Overall, these results suggested that instead of specific pharmacological inhibitors, use of chemopreventive agents with broad spectrum efficacy to inhibit IL-1beta-induced signaling cascades and iNOS expression would be a better strategy towards lung cancer prevention and/or treatment.

Alkylation of cysteine 468 in Stat3 defines a novel site for therapeutic development.

Stat3 is a latent transcription factor that promotes cell survival and proliferation and is often constitutively active in multiple cancers. Inhibition of Stat3 signaling pathways suppresses cell survival signals and leads to apoptosis in cancer cells, suggesting direct inhibition of Stat3 function is a viable therapeutic approach. Herein, we identify a small molecule, C48, as a selective Stat3-family member inhibitor. To determine its mechanism of action, we used site-directed mutagenesis and multiple biochemical techniques to show that C48 alkylates Cys468 in Stat3, a residue at the DNA-binding interface. We further demonstrate that C48 blocks accumulation of activated Stat3 in the nucleus in tumor cell lines that overexpress active Stat3, leading to impressive inhibition of tumor growth in mouse models. Collectively, these findings suggest Cys468 in Stat3 represents a novel site for therapeutic intervention and demonstrates the promise of alkylation as a potentially effective chemical approach for Stat3-dependent cancers.

Chondroitin sulfate inhibits lipopolysaccharide-induced inflammation in rat astrocytes by preventing nuclear factor kappa B activation.

Chondroitin sulfate (CS) is a glucosaminoglycan (GAG) currently used for the treatment of osteoarthritis because of its antiinflammatory and antiapoptotic actions. Recent evidence has revealed that those peripheral effects of CS may also have therapeutic interest in diseases of the CNS. Since neuroinflammation has been implicated in different neuronal pathologies, this study was planned to investigate how CS could modulate the inflammatory response in the CNS by using rat astrocyte cultures stimulated with lipopolysaccharide (LPS). We have evaluated different proteins implicated in the nuclear factor kappa B (NFkappaB) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways employing RT-PCR, western blot and immunofluorescence techniques. At 10 microM, CS prevented translocation of p65 to the nucleus, reduced tumour necrosis factor alpha (TNF-alpha) mRNA and mitigated cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) induction by LPS. However, it did not modify LPS-induced IP-10 and SOCS-1 mRNA, proteins that participate in the JAK/STAT pathway. The results of this study indicate that CS can potentially reduce neuroinflammation by inhibition of NFkappaB. Therefore endogenous GAGs could afford neuroimmunomodulatory actions under neurotoxic conditions.

Gonadotropin-releasing hormone modulates immune system function via the nuclear factor-kappaB pathway in murine Raw264.7 macrophages.

Gonadotropin-releasing hormone (GnRH), which was originally found to be involved in the reproductive process, has also been implicated in the modulation of immune system function. However, the underlying mechanisms of this involvement remain largely unclear. In this study, we found that GnRH increased the intracellular calcium levels in murine Raw264.7 macrophages. Furthermore, the production of nitric oxide, costimulated with lipopolysaccharide and interferon-gamma, was suppressed by exposure to GnRH. Moreover, the modulatory effects of GnRH on calcium and nitric oxide were observed in freshly isolated primary peritoneal macrophages. In addition, the activity of nuclear factor-kappaB was suppressed by GnRH exposure. On the other hand, the phosphorylation of the Janus kinase-signal transducer and activator of transcription pathway was not affected by cotreatment with GnRH. Taken together, these results demonstrate that GnRH participates in the macrophage function and indicate that the nuclear factor-kappaB signaling pathway may be responsible for GnRH-mediated immune system modulation.

Can the protective actions of JAK-STAT in the heart be exploited therapeutically? Parsing the regulation of interleukin-6-type cytokine signaling.

Activation of the transcription factor signal transducers and activators of transcription (STAT) 3 is a defining feature of the interleukin (IL)-6 family of cytokines, which include IL-6, leukemia inhibitory factor, and cardiotrophin-1. These cytokines, as well as STAT3 activation, have been shown to be protective for cardiac myocytes and necessary for ischemia preconditioning. However, the mechanisms that regulate IL-6-type cytokine signaling in cardiac myocytes are largely unexplored. We propose that the protective character of IL-6-type cytokine signaling in cardiac myocytes is determined principally by three mechanisms: redox status of the nonreceptor tyrosine kinase Janus kinase 1 (JAK) 1 that activates STAT3, phosphorylation of STAT3 within the transcriptional activation domain on serine 727, and STAT3-mediated induction of suppressor of cytokine signaling (SOCS) 3 that terminates IL-6-type cytokine signaling. Moreover, we hypothesize that hyperactivation of the JAK kinases, particularly JAK2, mismatched STAT3 serine-tyrosine phosphorylation or heightened STAT3 transcriptional activity, and SOCS3 induction may ultimately prove detrimental. Here we summarize recent evidence that supports this hypothesis, as well as additional possible mechanisms of JAK-STAT regulation. Understanding how IL-6-type cytokine signaling is regulated in cardiac myocytes has great significance for exploiting the therapeutic potential of these cytokines and the phenomenon of preconditioning.

Large-scale generation of highly enriched neural stem-cell-derived oligodendroglial cultures: maturation-dependent differences in insulin-like growth factor-mediated signal transduction.

Multipotent neural stem cells (NSCs) are competent for commitment to the oligodendrocyte (OL) lineage both in vitro and in vivo. We exploited this property to develop a rat neurospheres (NS)/oligospheres (OS)-based culture system to generate large numbers of highly enriched late OL progenitors (preOLs) and mature OLs (MatOLs). CNS neuroblastoma cell line B104-derived conditioned medium promoted the generation of nearly pure populations of preOLs from dissociated OS. The subsequent culture of preOLs with ciliary neurotrophic factor (CNTF) and 3,3',5'-triiodo-L-thyronine (T(3)) generated nearly pure populations of MatOLs. OL lineage specificity was confirmed by immunocytochemistry, quantitative RT-PCR and gene expression profiling, which demonstrated large differences between preOLs and MatOLs. The insulin-like growth factors (IGFs) are potent neuro-protective agents required for OL survival. We used this system to systematically define maturation-dependent changes in IGF signaling during the course of OL differentiation. The IGF-I and insulin receptors, insulin receptor substrate-1 (IRS-1) and IRS-2, protein kinase B (PKB)/Akt and Janus kinase (JNK) were expressed at higher levels in NS and preOLs compared with OS and MatOLs. Erk expression increased markedly from NS to OS, decreased only partially upon commitment to preOLs, and, in MatOLs, returned to a low level similar to NS. IGF activation of the generally proliferative Erk pathway was gradually acquired during NSC differentiation, whereas IGF activation of the generally pro-survival, anti-apoptotic PI3K/PKB pathway was consistently robust at each developmental stage.