Involvement of the JAK-STAT pathway in the molecular landscape of tyrosine kinase fusion-negative hypereosinophilic syndromes: A nationwide CEREO study.

We investigated using a custom NGS panel of 149 genes the mutational landscape of 64 consecutive adult patients with tyrosine kinase fusion-negative hypereosinophilia (HE)/hypereosinophilic syndrome (HES) harboring features suggestive of myeloid neoplasm. At least one mutation was reported in 50/64 (78%) patients (compared to 8/44 (18%) patients with idiopathic HE/HES/HEUS used as controls; p < .001). Thirty-five patients (54%) had at least one mutation involving the JAK-STAT pathway, including STAT5B (n = 18, among which the hotspot N642H, n = 13), JAK1 (indels in exon 13, n = 5; V658F/L, n = 2), and JAK2 (V617F, n = 6; indels in exon 13, n = 2). Other previously undescribed somatic mutations were also found in JAK2, JAK1, STAT5B, and STAT5A, including three patients who shared the same STAT5A V707fs mutation and features consistent with primary polycythemia. Nearly all JAK-STAT mutations were preceded by (or associated with) myelodysplasia-related gene mutations, especially in RNA-splicing genes or chromatin modifiers. In multivariate analysis, neurologic involvement (hazard ratio [HR] 4.95 [1.87-13.13]; p = .001), anemia (HR 5.50 [2.24-13.49]; p < .001), and the presence of a high-risk mutation (as per the molecular international prognosis scoring system: HR 6.87 [2.39-19.72]; p < .001) were independently associated with impaired overall survival. While corticosteroids were ineffective in all treated JAK-STAT-mutated patients, ruxolitinib showed positive hematological responses including in STAT5A-mutated patients. These findings emphasize the usefulness of NGS for the workup of tyrosine kinase fusion-negative HE/HES patients and support the use of JAK inhibitors in this setting. Updated classifications could consider patients with JAK-STAT mutations and eosinophilia as a new "gene mutated-entity" that could be differentiated from CEL, NOS, and idiopathic HES.

Individuals with JAK1 variants are affected by syndromic features encompassing autoimmunity, atopy, colitis, and dermatitis.

Inborn errors of immunity lead to autoimmunity, inflammation, allergy, infection, and/or malignancy. Disease-causing JAK1 gain-of-function (GoF) mutations are considered exceedingly rare and have been identified in only four families. Here, we use forward and reverse genetics to identify 59 individuals harboring one of four heterozygous JAK1 variants. In vitro and ex vivo analysis of these variants revealed hyperactive baseline and cytokine-induced STAT phosphorylation and interferon-stimulated gene (ISG) levels compared with wild-type JAK1. A systematic review of electronic health records from the BioME Biobank revealed increased likelihood of clinical presentation with autoimmunity, atopy, colitis, and/or dermatitis in JAK1 variant-positive individuals. Finally, treatment of one affected patient with severe atopic dermatitis using the JAK1/JAK2-selective inhibitor, baricitinib, resulted in clinically significant improvement. These findings suggest that individually rare JAK1 GoF variants may underlie an emerging syndrome with more common presentations of autoimmune and inflammatory disease (JAACD syndrome). More broadly, individuals who present with such conditions may benefit from genetic testing for the presence of JAK1 GoF variants.

Single-cell deconvolution algorithms analysis unveils autocrine IL11-mediated resistance to docetaxel in prostate cancer via activation of the JAK1/STAT4 pathway.

BACKGROUND: Docetaxel resistance represents a significant obstacle in the treatment of prostate cancer. The intricate interplay between cytokine signalling pathways and transcriptional control mechanisms in cancer cells contributes to chemotherapeutic resistance, yet the underlying molecular determinants remain only partially understood. This study elucidated a novel resistance mechanism mediated by the autocrine interaction of interleukin-11 (IL-11) and its receptor interleukin-11 receptor subunit alpha(IL-11RA), culminating in activation of the JAK1/STAT4 signalling axis and subsequent transcriptional upregulation of the oncogene c-MYC. METHODS: Single-cell secretion profiling of prostate cancer organoid was analyzed to determine cytokine production profiles associated with docetaxel resistance.Analysis of the expression pattern of downstream receptor IL-11RA and enrichment of signal pathway to clarify the potential autocrine mechanism of IL-11.Next, chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) was performed to detect the nuclear localization and DNA-binding patterns of phosphorylated STAT4 (pSTAT4). Coimmunoprecipitation and reporter assays were utilized to assess interaction between pSTAT4 and the cotranscription factor CREB-binding protein (CBP) as well as their role in c-MYC transcriptional activity. RESULTS: Autocrine secretion of IL-11 was markedly increased in docetaxel-resistant prostate cancer cells. IL-11 stimulation resulted in robust activation of JAK1/STAT4 signalling. Upon activation, pSTAT4 translocated to the nucleus and associated with CBP at the c-MYC promoter region, amplifying its transcriptional activity. Inhibition of the IL-11/IL-11RA interaction or disruption of the JAK1/STAT4 pathway significantly reduced pSTAT4 nuclear entry and its binding to CBP, leading to downregulation of c-MYC expression and restoration of docetaxel sensitivity. CONCLUSION: Our findings identify an autocrine loop of IL-11/IL-11RA that confers docetaxel resistance through the JAK1/STAT4 pathway. The pSTAT4-CBP interaction serves as a critical enhancer of c-MYC transcriptional activity in prostate cancer cells. Targeting this signalling axis presents a potential therapeutic strategy to overcome docetaxel resistance in advanced prostate cancer.

N-Acetylcysteine Alters Disease Progression and Increases Janus Kinase Mutation Frequency in a Mouse Model of Precursor B-Cell Acute Lymphoblastic Leukemia.

B-cell acute lymphoblastic leukemia (B-ALL) is the most prevalent type of cancer in young children and is associated with high levels of reactive oxygen species (ROS). The antioxidant N-acetylcysteine (NAC) was tested for its ability to alter disease progression in a mouse model of B-ALL. Mb1-CreΔPB mice have deletions in genes encoding PU.1 and Spi-B in B cells and develop B-ALL at 100% incidence. Treatment of Mb1-CreΔPB mice with NAC in drinking water significantly reduced the frequency of CD19+ pre-B-ALL cells infiltrating the thymus at 11 weeks of age. However, treatment with NAC did not reduce leukemia progression or increase survival by a median 16 weeks of age. NAC significantly altered gene expression in leukemias in treated mice. Mice treated with NAC had increased frequencies of activating mutations in genes encoding Janus kinases 1 and 3. In particular, frequencies of Jak3 R653H mutations were increased in mice treated with NAC compared with control drinking water. NAC opposed oxidization of PTEN protein ROS in cultured leukemia cells. These results show that NAC alters leukemia progression in this mouse model, ultimately selecting for leukemias with high Jak3 R653H mutation frequencies. SIGNIFICANCE STATEMENT: In a mouse model of precursor B-cell acute lymphoblastic leukemia associated with high levels of reactive oxygen species, treatment with N-acetylcysteine did not delay disease progression but instead selected for leukemic clones with activating R653H mutations in Janus kinase 3.

Regulatory function and mechanism research for m6A modification WTAP via SUCLG2-AS1- miR-17-5p-JAK1 axis in AML.

Acute myeloid leukemia (AML), characterized by the abnormal accumulation of immature marrow cells in the bone marrow, is a malignant tumor of the blood system. Currently, the pathogenesis of AML is not yet clear. Therefore, this study aims to explore the mechanisms underlying the development of AML. Firstly, we identified a competing endogenous RNA (ceRNA) SUCLG2-AS1-miR-17-5p-JAK1 axis through bioinformatics analysis. Overexpression of SUCLG2-AS1 inhibits proliferation, migration and invasion and promotes apoptosis of AML cells. Secondly, luciferase reporter assay and RIP assay validated that SUCLG2-AS1 functioned as ceRNA for sponging miR-17-5p, further leading to JAK1 underexpression. Additionally, the results of MeRIP-qPCR and m6A RNA methylation quantification indicted that SUCLG2-AS1(lncRNA) had higher levels of m6A RNA methylation compared with controls, and SUCLG2-AS1 is regulated by m6A modification of WTAP in AML cells. WTAP, one of the main regulatory components of m6A methyltransferase complexes, proved to be highly expressed in AML and elevated WTAP is associated with poor prognosis of AML patients. Taken together, the WTAP-SUCLG2-AS1-miR-17-5p-JAK1 axis played essential roles in the process of AML development, which provided a novel therapeutic target for AML.

Golidocitinib, a selective JAK1 tyrosine-kinase inhibitor, in patients with refractory or relapsed peripheral T-cell lymphoma (JACKPOT8 Part B): a single-arm, multinational, phase 2 study.

BACKGROUND: Golidocitinib, a selective JAK1 tyrosine-kinase inhibitor, has shown encouraging anti-tumour activity in heavily pre-treated patients with relapsed or refractory peripheral T-cell lymphoma in a phase 1 study (JACKPOT8 Part A). Here, we report the full analysis of a phase 2 study, in which we assessed the anti-tumour activity of golidocitinib in a large multinational cohort of patients. METHODS: We did a single-arm, multinational, phase 2 trial (JACKPOT8 Part B) in 49 centres in Australia, China, South Korea, and the USA. Eligible patients were adults (aged ≥18 years) with relapsed or refractory peripheral T-cell lymphoma who had received at least one previous line of systemic therapy and an Eastern Cooperative Oncology Group performance status of 0-2. Patients were given oral golidocitinib 150 mg once daily until disease progression or other discontinuation criteria were met. The primary endpoint was the CT-based objective response rate, assessed by an independent review committee (IRC) per Lugano 2014 classification. The activity analysis set included all patients who received at least one dose and whose pathological diagnosis of peripheral T-cell lymphoma had been retrospectively confirmed by a central laboratory and who had at least one measurable lesion at baseline assessed by IRC. The safety analysis set included all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov, NCT04105010, and is closed to accrual and follow-up is ongoing. FINDINGS: Between Feb 26, 2021, and Oct 12, 2022, we assessed 161 patients for eligibility, of whom 104 (65%) were enrolled and received at least one dose of study drug; the activity analysis set included 88 (85%) patients (median age 58 years [IQR 51-67], 57 [65%] of 88 were male, 31 [35%] were female, and 83 [94%] were Asian). As of data cutoff (Aug 31, 2023; median follow-up was 13·3 months [IQR 4·9-18·4]), per IRC assessment, the objective response rate was 44·3% (95% CI 33·7-55·3; 39 of 88 patients, p<0·0001), with 21 (24%) patients having a complete response and 18 (20%) having a partial response. In the safety analysis set, 61 (59%) of 104 patients had grade 3-4 drug-related treatment-emergent adverse events. The most common grade 3-4 drug-related treatment-emergent adverse events were neutrophil count decreased (30 [29%]), white blood cell count decreased (27 [26%]), lymphocyte count decreased (22 [21%]), and platelet count decreased (21 [20%]), which were clinically manageable and reversible. 25 (24%) patients had treatment-related serious adverse events. Deaths due to treatment-emergent adverse events occurred in three (3%) patients: two (2%) due to pneumonia (one case with fungal infection [related to golidocitinib] and another one with COVID-19 infection) and one (1%) due to confusional state. INTERPRETATION: In this phase 2 study, golidocitinib showed a favourable benefit-risk profile in treating relapsed or refractory peripheral T-cell lymphoma. The results of this study warrant further randomised clinical studies to confirm activity and assess efficacy in this population. FUNDING: Dizal Pharmaceutical.

CALCRL induces resistance to daunorubicin in acute myeloid leukemia cells through upregulation of XRCC5/TYK2/JAK1 pathway.

Chemotherapy is the main treatment option for acute myeloid leukemia (AML), but acquired resistance of leukemic cells to chemotherapeutic agents often leads to difficulties in AML treatment and disease relapse. High calcitonin receptor-like (CALCRL) expression is closely associated with poorer prognosis in AML patients. Therefore, this study was performed by performing CALCRL overexpression constructs in AML cell lines HL-60 and Molm-13 with low CALCRL expression. The results showed that overexpression of CALCRL in HL-60 and Molm-13 could confer resistance properties to AML cells and reduce the DNA damage and cell cycle G0/G1 phase blocking effects caused by daunorubicin (DNR) and others. Overexpression of CALCRL also reduced DNR-induced apoptosis. Mechanistically, the Cancer Clinical Research Database analyzed a significant positive correlation between XRCC5 and CALCRL in AML patients. Therefore, the combination of RT-PCR and Western blot studies further confirmed that the expression levels of XRCC5 and PDK1 genes and proteins were significantly upregulated after overexpression of CALCRL. In contrast, the phosphorylation levels of AKT/PKCε protein, a downstream pathway of XRCC5/PDK1, were significantly upregulated. In the response study, transfection of overexpressed CALCRL cells with XRCC5 siRNA significantly upregulated the drug sensitivity of AML to DNR. The expression levels of PDK1 protein and AKT/PKCε phosphorylated protein in the downstream pathway were inhibited considerably, and the expression of apoptosis-related proteins Bax and cleaved caspase-3 were upregulated. Animal experiments showed that the inhibitory effect of DNR on the growth of HL-60 cells and the number of bone marrow invasions were significantly reversed after overexpression of CALCRL in nude mice. However, infection of XCRR5 shRNA lentivirus in HL-60 cells with CALCRL overexpression attenuated the effect of CALCRL overexpression and upregulated the expression of apoptosis-related proteins induced by DNR. This study provides a preliminary explanation for the relationship between high CALCRL expression and poor prognosis of chemotherapy in AML patients. It offers a more experimental basis for DNR combined with molecular targets for precise treatment in subsequent studies.

Inhibiting JAK1, not NF-κB, reverses the effect of pro-inflammatory cytokines on engineered human ligament function.

The role of inflammation in chronic tendon/ligament injury is hotly debated. There is less debate about inflammation following acute injury. To better understand the effect of acute inflammation, in this study we developed a multi-cytokine model of inflammatory tendinitis. The combined treatment with TNF-α, IL-1ß, and IL-6, at dosages well below what are routinely used in vitro, decreased the mechanical properties and collagen content of engineered human ligaments. Treatment with this cytokine mixture resulted in an increase in phospho-NF-κB and MMP-1, did not affect procollagen production, and decreased STAT3 phosphorylation relative to controls. Using this more physiologically relevant model of acute inflammation, we inhibited NF-κB or JAK1 signaling in an attempt to reverse the negative effects of the cytokine mixture. Surprisingly, NF-κB inhibition led to an even greater decrease in mechanical function and collagen content. By contrast, inhibiting JAK1 led to an increase in mechanical properties, collagen content and thermal stability concomitant with a decrease in MMP-1. Our results suggest that inhibition of JAK1, not NF-κB, reverses the negative effects of pro-inflammatory cytokines on collagen content and mechanics in engineered human ligaments.

Structural Analysis of Janus Tyrosine Kinase Variants in Hematological Malignancies: Implications for Drug Development and Opportunities for Novel Therapeutic Strategies.

Janus tyrosine kinase (JAK) variants are known drivers for hematological disorders. With the full-length structure of mouse JAK1 being recently resolved, new observations on the localization of variants within closed, open, and dimerized JAK structures are possible. Full-length homology models of human wild-type JAK family members were developed using the Glassman et al. reported mouse JAK1 containing the V658F structure as a template. Many mutational sites related to proliferative hematological disorders reside in the JH2 pseudokinase domains facing the region important in dimerization of JAKs in both closed and open states. More than half of all JAK gain of function (GoF) variants are changes in polarity, while only 1.2% are associated with a change in charge. Within a JAK1-JAK3 homodimer model, IFNLR1 (PDB ID7T6F) and the IL-2 common gamma chain subunit (IL2Rγc) were aligned with the respective dimer implementing SWISS-MODEL coupled with ChimeraX. JAK3 variants were observed to encircle the catalytic site of the kinase domain, while mutations in the pseudokinase domain align along the JAK-JAK dimerization axis. FERM domains of JAK1 and JAK3 are identified as a hot spot for hematologic malignancies. Herein, we propose new allosteric surfaces for targeting hyperactive JAK dimers.

Allosteric TYK2 inhibition: redefining autoimmune disease therapy beyond JAK1-3 inhibitors.

JAK inhibitors impact multiple cytokine pathways simultaneously, enabling high efficacy in treating complex diseases such as cancers and immune-mediated disorders. However, their broad reach also poses safety concerns, which have fuelled a demand for increasingly selective JAK inhibitors. Deucravacitinib, a first-in-class allosteric TYK2 inhibitor, represents a remarkable advancement in the field. Rather than competing at kinase domain catalytic sites as classical JAK1-3 inhibitors, deucravacitinib targets the regulatory pseudokinase domain of TYK2. It strikingly mirrors the functional effect of an evolutionary conserved naturally occurring TYK2 variant, P1104A, known to protect against multiple autoimmune diseases yet provide sufficient TYK2-mediated cytokine signalling required to prevent immune deficiency. The unprecedentedly high functional selectivity and efficacy-safety profile of deucravacitinib, initially demonstrated in psoriasis, combined with genetic support, and promising outcomes in early SLE clinical trials make this inhibitor ripe for exploration in other autoimmune diseases for which better, safe, and efficacious treatments are urgently needed.

m6A-modified circNFIX promotes ovarian cancer progression and immune escape via activating IL-6R/JAK1/STAT3 signaling by sponging miR-647.

BACKGROUND: Ovarian cancer (OC) is one of the most common gynecological malignant cancers. Our previous work confirmed that circNFIX acted as an oncogene in OC, which could promote malignant proliferation, metastasis and angiogenesis. However, the role and mechanism of circNFIX in OC immune escape remain unclear. METHODS: The RNA and protein levels were determined by qRT-PCR and western blot assays. The malignant phenotypes were tested by cell count kit-8, EdU staining, flow cytometry and transwell assays. The immune cytokines levels were measured by ELISA analysis. Molecular interactions were verified employing RNA immunoprecipitation, meRIP and dual luciferase methods. In vivo validation was performed by xenograft tumor and lung metastasis model. Hematoxylin & eosin and immunohistochemistry staining were used to observe the pathological changes. RESULTS: The levels of circNFIX, PD-L1, and IL-6R were upregulated in OC tissues and cell lines, while miR-647 was downregulated. Functional assays showed that loss of circNFIX suppressed the growth, metastasis and immune escape of OC cells both in vitro and in vivo. On the molecular level, the m6A modification of circNFIX was elevated in OC cells, and its expression was positively correlated to m6A modification and depended on IGF2BP1 âˆ¼ 3 recognition. Moreover, circNFIX acted as a competing endogenous RNA for miR-647 to upregulate IL-6R expression, thereby activating JAK/STAT3 signaling and elevating PD-L1 expression. Rescue assays revealed that co-silencing of miR-647 reversed the antitumor effects of circNFIX knockdown on cell proliferation, metastasis and immune escape of OC cells. CONCLUSION: This study provided a comprehensive understanding of the molecular mechanism about circNFIX in OC, demonstrating m6A activated-circNFIX accelerated OC development and immune escape via regulating miR-647/IL-6R/PD-L1 pathway.

JAK3 Y841 Autophosphorylation Is Critical for STAT5B Activation, Kinase Domain Stability and Dimer Formation.

Janus tyrosine kinase 3 (JAK3) is primarily expressed in immune cells and is needed for signaling by the common gamma chain (γc) family of cytokines. Abnormal JAK3 signal transduction can manifest as hematological disorders, e.g., leukemia, severe combined immunodeficiency (SCID) and autoimmune disease states. While regulatory JAK3 phosphosites have been well studied, here a functional proteomics approach coupling a JAK3 autokinase assay to mass spectrometry revealed ten previously unreported autophosphorylation sites (Y105, Y190, Y238, Y399, Y633, Y637, Y738, Y762, Y824, and Y841). Of interest, Y841 was determined to be evolutionarily conserved across multiple species and JAK family members, suggesting a broader role for this residue. Phospho-substitution mutants confirmed that Y841 is also required for STAT5 tyrosine phosphorylation. The homologous JAK1 residue Y894 elicited a similar response to mutagenesis, indicating the shared importance for this site in JAK family members. Phospho-specific Y841-JAK3 antibodies recognized activated kinase from various T-cell lines and transforming JAK3 mutants. Computational biophysics analysis linked Y841 phosphorylation to enhanced JAK3 JH1 domain stability across pH environments, as well as to facilitated complementary electrostatic JH1 dimer formation. Interestingly, Y841 is not limited to tyrosine kinases, suggesting it represents a conserved ubiquitous enzymatic function that may hold therapeutic potential across multiple kinase families.

Palmitoylation-dependent control of JAK1 kinase signaling governs responses to neuropoietic cytokines and survival in DRG neurons.

Janus Kinase-1 (JAK1) plays key roles during neurodevelopment and following neuronal injury, while activatory JAK1 mutations are linked to leukemia. In mice, Jak1 genetic deletion results in perinatal lethality, suggesting non-redundant roles and/or regulation of JAK1 for which other JAKs cannot compensate. Proteomic studies reveal that JAK1 is more likely palmitoylated compared to other JAKs, implicating palmitoylation as a possible JAK1-specific regulatory mechanism. However, the importance of palmitoylation for JAK1 signaling has not been addressed. Here, we report that JAK1 is palmitoylated in transfected HEK293T cells and endogenously in cultured Dorsal Root Ganglion (DRG) neurons. We further use comprehensive screening in transfected non-neuronal cells and shRNA-mediated knockdown in DRG neurons to identify the related enzymes ZDHHC3 and ZDHHC7 as dominant protein acyltransferases (PATs) for JAK1. Surprisingly, we found palmitoylation minimally affects JAK1 localization in neurons, but is critical for JAK1's kinase activity in cells and even in vitro. We propose this requirement is likely because palmitoylation facilitates transphosphorylation of key sites in JAK1's activation loop, a possibility consistent with structural models of JAK1. Importantly, we demonstrate a leukemia-associated JAK1 mutation overrides the palmitoylation-dependence of JAK1 activity, potentially explaining why this mutation is oncogenic. Finally, we show that JAK1 palmitoylation is important for neuropoietic cytokine-dependent signaling and neuronal survival and that combined Zdhhc3/7 loss phenocopies loss of palmitoyl-JAK1. These findings provide new insights into the control of JAK signaling in both physiological and pathological contexts.

Successful treatment of JAK1-associated inflammatory disease.

BACKGROUND: Gain-of-function variants of JAK1 drive a rare immune dysregulation syndrome associated with atopic dermatitis, allergy, and eosinophilia. OBJECTIVES: This study sought to describe the clinical and immunological characteristics associated with a new gain-of-function variant of JAK1 and report the therapeutic efficacy of Janus kinase (JAK) inhibition. METHODS: The investigators identified a family affected by JAK1-associated autoinflammatory disease and performed clinical assessment and immunological monitoring on 9 patients. JAK1 signaling was studied by flow and mass cytometry in patients' cells at basal state or after immune stimulation. A molecular disease signature in the blood was studied at the transcriptomic level. Patients were treated with 1 of 2 JAK inhibitors: either baricitinib or upadacitinib. Clinical, cellular, and molecular response were evaluated over a 2-year period. RESULTS: Affected individuals displayed a syndromic disease with prominent allergy including atopic dermatitis, ichthyosis, arthralgia, chronic diarrhea, disseminated calcifying fibrous tumors, and elevated whole blood histamine levels. A variant of JAK1 localized in the pseudokinase domain was identified in all 9 affected, tested patients. Hyper-phosphorylation of STAT3 was found in 5 of 6 patients tested. Treatment of patients' cells with baricitinib controlled most of the atypical hyper-phosphorylation of STAT3. Administration of baricitinib to patients led to rapid improvement of the disease in all adults and was associated with reduction of systemic inflammation. CONCLUSIONS: Patients with this new JAK1 gain-of-function pathogenic variant displayed very high levels of blood histamine and showed a variable combination of atopy with articular and gastrointestinal manifestations as well as calcifying fibrous tumors. The disease, which appears to be linked to STAT3 hyperactivation, was well controlled under treatment by JAK inhibitors in adult patients.

IFNγ induces Bcl3 expression by JAK1/STAT1/p65 signaling, resulting in increased IL-8 expression in ovarian cancer cells.

We have recently shown that IFNγ, produced during cancer therapy, induces expression of the Bcl3 proto-oncogene in ovarian cancer (OC) cells, resulting in their increased proliferation, migration, and invasion, but the mechanisms are unknown. Here, we demonstrate that the IFNγ-induced Bcl3 expression is dependent on JAK1 and STAT1 signaling, and on p65 NFκB. Furthermore, the IFNγ-induced Bcl3 expression is associated with an increased occupancy of Ser-727 phosphorylated STAT1 and acetylated histone H3 at the Bcl3 promoter. Our data indicate that Bcl3 promotes expression of the pro-inflammatory chemokine interleukin-8 (IL-8) in OC cells. These findings identify Bcl3 as a novel target of IFNγ/JAK1/STAT1 signaling and suggest that targeting the JAK1/STAT1 pathway may suppress IFNγ-induced Bcl3 expression in OC.

EPN3 plays oncogenic role in non-small cell lung cancer by activating the JAK1/2-STAT3 pathway.

The effect of Epsin 3 (EPN3) on non-small cell lung cancer (NSCLC) has not yet been clearly elucidated. This study identified the exact function of EPN3 on NSCLC progression. EPN3 expression in NSCLC patients were analyzed based on the Cancer Genome Atlas database. Kaplan-Meier analysis was implemented to research the effect of EPN3 on patients' survival. EPN3 expression in clinical tissues of 62 NSCLC cases was monitored by real-time quantitative reverse transcription polymerase chain reaction, immunohistochemistry and Western blot. A549 and H1299 cells were transfected with EPN3 shRNA and treated by RO8191 (20 µM). Proliferation was researched by cell counting kit-8 and 5-ethnyl-2 deoxyuridine assays. Apoptosis was monitored by flow cytometry. Migration and invasion was assessed by Transwell experiment. EPN3 effect on A549 cell in vivo growth was researched using nude mice. RO8191 (200 µg) was intratumoral injected into mice. Immunohistochemistry and Western blot was implemented to monitor protein expression in cells and xenograft tumor tissues. EPN3 was abnormally up-regulated in NSCLC patients and cells, indicating a lower overall survival. Loss of EPN3 weakened proliferation, migration and invasion, induced apoptosis, and repressed epithelial-mesenchymal transition in NSCLC cells. Loss of EPN3 inactivated the JAK1/2-STAT3 pathway in NSCLC cells. RO8191 treatment reversed the inhibition of EPN3 knockdown on the malignant phenotype of NSCLC cells. RO8191 intratumoral injection reversed the suppression of EPN3 silencing on NSCLC cell in vivo growth. EPN3 acted as an oncogene in NSCLC via activating the JAK1/2-STAT3 pathway. EPN3 may be a promising target for NSCLC treatment.

JAK1 Pseudokinase V666G Mutant Dominantly Impairs JAK3 Phosphorylation and IL-2 Signaling.

Overactive Janus kinases (JAKs) are known to drive leukemia, making them well-suited targets for treatment. We sought to identify new JAK-activating mutations and instead found a JAK1-inactivating pseudokinase mutation, V666G. In contrast to other pseudokinase mutations that canonically lead to an active kinase, the JAK1 V666G mutation led to under-activation seen by reduced phosphorylation. To understand the functional role of JAK1 V666G in modifying kinase activity we investigated its influence on other JAK kinases and within the Interleukin-2 pathway. JAK1 V666G not only inhibited its own activity, but its presence could inhibit other JAK kinases. These findings provide new insights into the potential of JAK1 pseudokinase to modulate its own activity, as well as of other JAK kinases. Thus, the features of the JAK1 V666 region in modifying JAK kinases can be exploited to allosterically inhibit overactive JAKs.

LINC00659 cooperated with ALKBH5 to accelerate gastric cancer progression by stabilising JAK1 mRNA in an m6 A-YTHDF2-dependent manner.

BACKGROUND: N6-methyladenosine (m6 A) RNA modification is known as a common epigenetic regulation form in eukaryotic cells. Emerging studies show that m6 A in noncoding RNAs makes a difference, and the aberrant expression of m6 A-associated enzymes may cause diseases. The demethylase alkB homologue 5 (ALKBH5) plays diverse roles in different cancers, but its role during gastric cancer (GC) progression is not well known. METHODS: The quantitative real-time polymerase chain reaction, immunohistochemistry staining and western blotting assays were used to detect ALKBH5 expression in GC tissues and human GC cell lines. The function assays in vitro and xenograft mouse model in vivo were used to investigate the effects of ALKBH5 during GC progression. RNA sequencing, MeRIP sequencing, RNA stability and luciferase reporter assays were performed to explore the potential molecular mechanisms involved in the function of ALKBH5. RNA binding protein immunoprecipitation sequencing (RIP-seq), RIP and RNA pull-down assays were performed to examine the influence of LINC00659 on the ALKBH5-JAK1 interaction. RESULTS: ALKBH5 was highly expressed in GC samples and associated with aggressive clinical features and poor prognosis. ALKBH5 promoted the abilities of GC cell proliferation and metastasis in vitro and in vivo. The m6 A modification on JAK1 mRNA was removed by ALKBH5, which resulted in the upregulated expression of JAK1. LINC00659 facilitated ALKBH5 binding to and upregulated JAK1 mRNA depending on an m6 A-YTHDF2 manner. Silencing of ALKBH5 or LINC00659 disrupted GC tumourigenesis via the JAK1 axis. JAK1 upregulation activated the JAK1/STAT3 pathway in GC. CONCLUSION: ALKBH5 promoted GC development via upregulated JAK1 mRNA expression mediated by LINC00659 in an m6 A-YTHDF2-dependent manner, and targeting ALKBH5 may be a promising therapeutic method for GC patients.

LncRNA HAGLR silencing inhibits IL-1ß-induced chondrocytes inflammatory injury via miR-130a-3p/JAK1 axis.

BACKGROUND: Osteoarthritis (OA), the most common form of arthritis, is accompanied by destruction of articular cartilage, development of osteophyte and sclerosis of subchondral bone. This study aims to explore whether lncRNA HAGLR can play a role in OA, and further clarify the potential mechanism. MATERIAL AND METHODS: StarBase and luciferase reporter assay were applied for predicting and confirming the interaction between lncRNA HAGLR, miR-130a-3p and JAK1. The levels of lncRNA HAGLR and miR-130a-3p were analyzed using quantitative reverse transcription PCR (qRT-PCR). The proliferation, cytotoxicity and apoptosis of CHON-001 cells were evaluated by MTT, lactate dehydrogenase assay (LDH) and Flow cytometry (FCM) analysis, respectively. Moreover, expression of cleaved Caspase3 protein were determined by Western blot assay. The release of inflammatory factors (TNF-α, IL-8, and IL-6) was detected by ELISA. RESULTS: lncRNA HAGLR directly targets miR-130a-3p. Level of lncRNA HAGLR was substantially higher and miR-130a-3p level was memorably lower in IL-1ß stimulated CHON-001 cells than that in Control group. Furthermore, lncRNA HAGLR silencing alleviated IL-1ß induce chondrocyte inflammatory injury, as evidenced by increased cell viability, reduced LDH release, decreased apoptotic cells, inhibited cleaved-Caspase3 expression, and reduced secretion of secretion of inflammatory factors. However, miR-130a-3p-inhibitor reversed these findings. We also found miR-130a-3p directly targeted JAK1 and negatively regulated JAK1 expression in CHON-001 cells. In addition, JAK1-plasmid reversed the effects of miR-130a-3p mimic on IL-1ß-induced chondrocytes inflammatory injury. CONCLUSION: Silencing of lncRNA HAGLR alleviated IL-1ß-stimulated CHON-001 cells injury through miR-130a-3p/JAK1 axis, revealing lncRNA HAGLR may be a valuable therapeutic target for OA therapy.