Inhibition Of STAT3 Phosphorylation Research Articles

Heparan sulfate acts in synergy with tight junction through STAT3 signaling to maintain the endothelial barrier and prevent lung injury development.

Damage to glycocalyx and tight junction are key determinants of endothelial permeability, which is the main pathological feature of acute respiratory distress syndrome (ARDS). However, the effect of glycocalyx heparan sulfate (HS) on tight junction proteins occludin and ZO-1 has not been revealed. In this study, the mice exposed to LPS results showed that FITC-albumin infiltration, HS shedding, and tight junction protein impairment were most severe at 6h of LPS treatment compared with those in other treatment times. The in vitro and vivo experiments revealed that tight junction damage, FITC-albumin infiltration, and pathological injury induced by LPS were significantly alleviated via protection of glycocalyx HS shedding. mRNA sequencing analysis demonstrated that the STAT signaling pathways played a crucial role in the inhibition of LPS-induced HS shedding in mice. Supplementation of exogenous HS in human umbilical vein endothelial cells (HUVECs) and mice ameliorated LPS-induced the tight junction barrier defect by inhibiting STAT3 phosphorylation. Further analysis uncovered that intervention of STAT3 signaling significantly alleviated LPS-induced tight junction proteins damage and vascular permeability in HUVECs and mice. Mechanistically, HS modulated tight junction proteins by STAT3 signaling, which might directly bind to the promoter regions of occludin and ZO-1. In conclusion, glycocalyx HS played an important role in protecting endothelial barrier function and preventing injury development, in synergy with tight junction through STAT3 signaling, which further alleviated pulmonary edema.

LPS Disrupts Endometrial Receptivity by Inhibiting STAT1 Phosphorylation in Sheep

Uterine infections reduce ruminant reproductive efficiency. Reproductive dysfunction caused by infusion of Gram-negative bacteria is characterized by the failure of embryo implantation and reduced conception rates. Lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria, is highly abortogenic. In this study, the effects of LPS infusion on the endometrial receptivity of sheep were studied during three critical periods of embryo implantation. The results showed that LPS infusion on d12, d16, and d20 of pregnancy in vivo interfered with the expression of prostaglandins (PGs) and affected the expression of adhesion-related factors (ITGB1/3/5, SPP1), key implantation genes (HOXA10, HOXA11 and LIF), and progestational elongation genes (ISG15, RSAD2 and CXCL10) during embryo implantation. In addition, after LPS infusion on d12, d16, and d20, the phosphorylation level of STAT1 significantly decreased and the protein expression level of IRF9 significantly increased on d12, suggesting that LPS infusion in sheep impairs endometrial receptivity through the JAK2/STAT1 pathway. Sheep endometrial epithelial cells were treated with 17 β-estrogen, progesterone, and/or interferon-tau in vitro to mimic the receptivity of the endometrium during early pregnancy for validation. LPS and the p-STAT1 inhibitor fludarabine were both added to the model, which resulted in reduced p-STAT1 protein expression, significant inhibition of PGE2/PGF2α, and significant suppression of the expression of key embryo implantation genes. Collectively, these results indicate that LPS infusion in sheep on d12, d16, and d20 impairs endometrial receptivity through the JAK2/STAT1 pathway, which is responsible for LPS-associated pregnancy failure.

Pentagalloyl Glucose from Bouea macrophylla Suppresses the Epithelial-Mesenchymal Transition and Synergizes the Doxorubicin-Induced Anticancer and Anti-Migration Effects in Triple-Negative Breast Cancer.

Background: Triple-negative breast cancer (TNBC) represents an aggressive form of breast cancer with few available therapeutic options. Chemotherapy, particularly with drugs like doxorubicin (DOX), remains the cornerstone of treatment for this challenging subtype. However, the clinical utility of DOX is hampered by adverse effects that escalate with higher doses and drug resistance, underscoring the need for alternative therapies. This study explored the efficacy of pentagalloyl glucose (PGG), a natural polyphenol derived from Bouea macrophylla, in enhancing DOX's anticancer effects and suppressing the epithelial-mesenchymal transition (EMT) in TNBC cells. Methods: This study employed diverse methodologies to assess the effects of PGG and DOX on TNBC cells. MDA-MB231 triple-negative breast cancer cells were used to evaluate cell viability, migration, invasion, apoptosis, mitochondrial membrane potential, and protein expression through techniques including MTT assays, wound healing assays, flow cytometry, Western blotting, and immunofluorescence. Results: Our findings demonstrate that PGG combined with DOX significantly inhibits TNBC cell proliferation, migration, and invasion. PGG enhances DOX-induced apoptosis by disrupting the mitochondrial membrane potential and activating caspase pathways; consequently, the activation of caspase-3 and the cleavage of PARP are increased. Additionally, the study shows that the combination treatment upregulates ERK signaling, further promoting apoptosis. Moreover, PGG reverses DOX-induced EMT by downregulating mesenchymal markers (vimentin and β-catenin) and upregulating epithelial markers (E-cadherin). Furthermore, it effectively inhibits STAT3 phosphorylation, associated with cell survival and migration. Conclusions: These results highlight the potential of PGG as an adjuvant therapy in TNBC treatment. PGG synergizes with DOX, which potentiates its anticancer effects while mitigating adverse reactions.

HMGB3 Contributes to Anti-PD-1 Resistance by Inhibiting IFN-γ-Driven Ferroptosis in TNBC.

Our previous studies showed HMGB3 expression may correlate with immunotherapy efficacy in breast cancer patients. Here, we investigated whether HMGB3 overexpression has an impact on anti-PD-1 therapy in triple-negative breast cancer (TNBC) and its molecular mechanisms. Animal models were established to observe the effect of HMGB3 on sensitivity to anti-PD-1 treatment. Correlation of HMGB3 expression and ferroptosis preventive proteins in TNBC patients' tissues with anti-PD-1 therapy efficacy was analyzed. The impact of HMGB3 on IFN-γ (Interferon-gamma) inhibitory effects and signaling was examined in human TNBC cells where HMGB3 expression was knocked down using siRNA. Moreover, TNBC cells stably transfected with lentiviral vectors containing cDNA of HMGB3 were also used to confirm the effect of overexpression of HMGB3 on IFN-γ inhibitory effect and signaling. Effect of HMGB3 on IFN-γ-driven ferroptosis and ferroptosis-associated protein expression were also investigated. Correlation of HMGB3 and IRF1 and GPX4 expression in patient's cancer tissue were also investigated. Our results demonstrated that HMGB3 expression contributes to resistance to anti-PD-1 therapy in vivo. HMGB3 expression correlated with treatment efficacy of immunotherapy and survival in TNBC patients. HMGB3 silence decreased resistance of breast cancer cells to IFN-γ cytotoxic effect, while HMGB3 overexpression increased resistance of these cancer cells. HMGB3 silence increased STAT1 phosphorylation and IRF1 expression upon IFN-γ treatment compared with control. Overexpression of HMGB3 inhibited STAT1 phosphorylation and IFN-γ signaling in TNBC cells. Moreover, HMGB3 also increased STAT3 activation and had an effect of interaction between STAT1 and STAT3. HMGB3 overexpression decreased IFN-γ-driven ferroptosis in TNBC cells. HMGB3 increased ferroptosis-inhibitory proteins (SLC7A11, GPX4, and SLC3A2) expression in TNBC cells. Ferroptosis inhibition recovers resistance to anti-PD-1 therapy in vivo. Immunohistochemistry showed HMGB3 expression correlated with ferroptosis-associated proteins and IRF1 expression in breast cancer tissue. HMGB3 contributes to anti-PD-1 resistance by inhibiting IFN-γ-driven ferroptosis in TNBC which suggested HMGB3 is a potential co-target with anti-PD-1 therapy for TNBC.

Stattic suppresses p‑STAT3 and induces cell death in T‑cell acute lymphoblastic leukemia.

The present study investigated the therapeutic potential of Stattic, a selective inhibitor of STAT3, in treating T‑cell acute lymphoblastic leukemia (T‑ALL). The effects of Stattic on cell viability, STAT3 phosphorylation, apoptosis and autophagy in T‑ALL cell lines, and on tumor growth in a xenograft mouse model of T‑ALL, were assessed. Methods, including the Cell Counting Kit‑8 assay for cell viability, propidium iodide/Annexin V staining for apoptosis detection, western blotting for protein expression analysis, and a xenograft mouse model for evaluating in vivo tumor growth, were employed. The results showed that Stattic effectively reduced cell viability in a dose‑dependent manner, with significant reductions observed at concentrations of 1.25 µM and above in CCRF‑CEM cells (IC50=3.188 µM) and at 2.5 µM and above in Jurkat cells (IC50=4.89 µM) after 24 h of treatment. Concurrently, Stattic significantly suppressed the expression of phosphorylated STAT3, indicating its mechanism of action as a STAT3 pathway inhibitor. Furthermore, Stattic treatment induced both apoptosis and autophagy in CCRF‑CEM and Jurkat cells, as evidenced by the respective upregulation of cleaved caspase‑3 and LC3B. In a xenograft mouse model of T‑ALL, Stattic markedly inhibited tumor growth, with the greatest effect occurring at the highest dose of 30 mg/kg. These results suggested that Stattic holds promise as a therapeutic agent in T‑ALL by modulating key pathways involved in cell survival and proliferation. In conclusion, Stattic exhibited a significant therapeutic potential for T‑ALL via a dose‑dependent reduction of cell viability, inhibiting STAT3 phosphorylation, and promoting both apoptotic and autophagic cell death; however, further studies are required before clinical application.

Curculigoside upregulates BMAL1 to decrease nucleus pulposus cell apoptosis by inhibiting the JAK/STAT3 pathway

BackgroundIntervertebral disc degeneration (IVDD) is a natural process that occurs with aging and is the main cause of low back pain (LBP). Basic helix-loop-helix ARNT-like 1 (BMAL1) plays key roles in the pathogenesis of many diseases. The present study investigates the role of curculigoside (CUR), which has been reported to be a potential anti-apoptotic compound in other diseases. MethodsDysregulated genes were identified by RNA sequencing (RNA-seq). Western blotting (WB), immunohistochemistry (IHC), immunofluorescence (IF) staining, and real-time fluorescent quantitative PCR were used to detect BMAL1 expression in 25 human intervertebral disc (IVD) specimens (male: female =13:12), tissues from BMAL1-knockout mice and from an IVDD mouse model. The regulatory effects of CUR and BMAL1 in NP cells after siRNA transfection were examined by flow cytometry, IF staining and WB. The therapeutic effect of intraperitoneal CUR injection was also evaluated in mice. ResultsBMAL1 expression was negatively correlated with IVDD severity and was significantly lower in degenerative NP cells. After BMAL1 knockdown using siRNA, the apoptosis rate of degenerative NP cells was significantly higher, while transfection with a lentivirus overexpressing BMAL1 exerted the opposite effect. Bioinformatics analysis revealed that BMAL1 is regulated by the JAK-STAT3 pathway, and CUR upregulated BMAL1 expression by inhibiting STAT3 phosphorylation, subsequently alleviating NP cell apoptosis and increasing extracellular matrix (ECM) components., thus alleviating IVDD. ConclusionsCUR can inhibit apoptosis and improve the ECM by upregulating BMAL1 expression, which is reduced in IVDD. This study provides a therapeutic strategy to alleviate apoptosis associated with inflammation-induced IVDD.

The Role of Delta-Opioid Receptor in Mediating the Cardioprotective Effects of Morphine Preconditioning via the JAK2/STAT3 Pathway in a Failing Heart

BACKGROUND: Failing heart is more likely to suffer from myocardial ischemia/reperfusion (I/R) injury. This poses a great challenge for anesthesiologists in managing patients with heart failure during major surgery. Evidence from animal studies suggests that the delta-opioid receptor (DOR) contributes to alleviating acute myocardial injuries. However, little is known regarding the cardioprotective effects of cardiac DOR in patients with chronic heart failure. This study aimed to examine DOR expression in failing hearts and explore how DOR regulates the Janus kinase signal transducer and activator of the transcription-3 (JAK/STAT3) pathway to mediate morphine-induced cardio protection in heart failure. METHODS: We measured the DOR protein levels in human and rat heart tissues with chronic heart failure. To investigate the cardioprotective role of DOR, we administered the DOR-specific antagonist, naltrindole (NTD), and JAK2 inhibitor, AG490, before morphine preconditioning (MPC) in an isolated perfusion model of myocardial I/R injury in postinfarcted failing rat heart. We examined the infarct size, cardiac enzymes, cardiac function, cardiomyocyte apoptosis, apoptosis-related proteins, and STAT3 phosphorylation in the heart. RESULTS: The protein levels of DOR were significantly elevated in the myocardial tissues of humans and rats with chronic heart failure, by 1.4-fold (mean difference 0.41; 95% confidence interval [CI], 0.04–0.78; P = .032) and 2.3-fold (mean difference 1.26; 95% CI, 0.25–2.28; P = .009), respectively, compared to control tissues. Disease severity positively correlated with DOR expression (human: R2 = 0.316, P = .004; rat: R2 = 0.871, P = .021). Blocking DOR substantially reversed the cardioprotective effects of MPC in postinfarcted rat hearts, increasing the mean (standard deviation) percentage of infarct size from 15.0 (3.9)% to 30.8 (7.7)% (P < .001). Similarly, AG490 inhibited MPC restoration of cardiomyocyte apoptosis (33.3 [4.2]% vs 16.6 [3.4]%; P < .001). Both NTD and AG490 markedly suppressed STAT3 phosphorylation by 60.1% (mean difference 0.60; 95% CI, 0.27–0.93; P = .002) and 44.1% (mean difference 0.44; 95% CI, 0.06–0.83; P = .027), respectively, and also lowered the Bcl-2/Bax ratio by 85.5% (mean difference 0.86; 95% CI, 0.28–1.43; P = .006) and 68.2% (mean difference 0.68; 95% CI, 0.51–0.85; P < .001) respectively in heart tissues at the end of reperfusion. CONCLUSIONS: DOR protein levels increased in failing hearts of both humans and rats. Blocking cardiac DOR selectively reduced morphine-induced cardio protection by inhibiting the JAK2/STAT3 pathway. These findings indicate that cardiac DOR is a potential therapeutic target for protecting against heart failure due to I/R injury.

Stretched Vascular Endothelial Cells Polarized Neutrophils to N2 Type via TRPC1-IL13-STAT3 Axis.

VECs play a crucial role in regulating the function of neutrophils, which is essential for immune responses and inflammation. As stretch-sensitive cells, VECs sense mechanical stretch through surface mechanoreceptors, converting external mechanical stimuli into biochemical signals. This study aimed to explore the molecular mechanisms underlying the regulation of neutrophil behavior by stretched VECs. The key cytokine-inducing neutrophil N2 polarization in the conditioned medium from stretched vascular endothelial cells (CM-stretch) was validated through multifactorial matrix and flow cytometry. Additionally, the molecular mechanism underlying the response of vascular endothelial cells to stretch was systematically verified through layer-by-layer analysis using WB. IL13, not IL4, was ultimately identified as a key cytokine-inducing neutrophil N2 polarization in CM-stretch. Inhibition of the transient receptor potential channel (TRPC1) and siRNA-mediated knockdown of TRPC1 both significantly decreased IL13 production. Furthermore, neutralizing IL13 in the CM-stretch or inhibiting STAT3 phosphorylation inhibited neutrophil N2 polarization, as evidenced by reduced CD206 and VEGFA expression. These results demonstrate that stretched VECs initiate a signaling cascade that induces neutrophil N2 polarization through the TRPC1-IL13-STAT3 axis, suggesting that mechanical stretching of VECs could shift neutrophil function from a pro-inflammatory to a more regulatory and healing role.

Gene Therapy for Inflammatory Cascade in Intrauterine Injury with Engineered Extracellular Vesicles Hybrid Snail Mucus-enhanced Adhesive Hydrogels.

Early hyper-inflammation caused by intrauterine injury triggered subsequent intrauterine adhesion (IUA). STAT1-mediated M1 macrophages are confirmed to secrete pro-inflammatory cytokines to accelerate inflammatory cascade and IUA formation by multi-omics analysis and experimental verification. However, clinically used hyaluronic acid (HA) hydrogels are prone to slip out of injury sites due to poor bio-adhesion properties. Therefore, there are still challenges in applying hydrogels for M1 macrophage intervention in IUA treatment. Herein, an engineered extracellular vesicles (EVs) hybrid snail mucus (SM)-enhanced adhesive hydrogels to improve bio-adhesion property is fabricated and M1 macrophage intervention through targeting delivery and STAT1 silencing is achieved. First, inspired by the high bio-adhesion capacity of SM, SM and gelatin methacrylate (GelMA) solution are mixed to construct GelMA/SM (GS) hydrogel. Then, folic acid-modified extracellular vesicles (FA-EVs) are synthesized for targeting the delivery of STAT1-siRNA. Upon injection of FA-EVs hybrid GS hydrogel into the uterine cavity, a protective hydrogel layer forms on the surface of injury sites and sustains the release of STAT1-siRNA-loaded FA-EVs to curtail M1 macrophages generation through inhibiting STAT1 phosphorylation, resulting in reduction of myofibroblasts activation and collagen deposition. In addition, the pregnancy rate and the number of fetuses in rats treated with this hydrogel were much higher than those in other groups, suggesting that the hydrogel could promote functional endometrial regeneration and restore fertility. Overall, this study presents a promising strategy for employing FA-EVs hybrid adhesive hydrogel with superior bio-adhesion properties and M1 macrophage targeting delivery for IUA treatment and uterus recovery.

Naringenin alleviates intestinal ischemia/reperfusion injury by inhibiting ferroptosis via targeting YAP/STAT3 signaling axis

BackgroundIntestinal ischemia/reperfusion injury (IRI) is a significant clinical emergency, and investigating novel therapeutic approaches and understanding their underlying mechanisms is essential for improving patient outcomes. Naringenin (Nar), a flavanone present in tomatoes and citrus fruits, is frequently consumed in the human diet and recognized for having immunomodulatory, anti-inflammatory, and antioxidant properties. Despite Nar being able to alleviate intestinal IRI, the exact molecular mechanisms remain elusive. PurposeTo investigate Nar's protective properties on intestinal IRI and elucidate the mechanisms, a comprehensive approach that combines network pharmacology analysis with experimental verification in vitro and in vivo was adopted. MethodsThe oxygen-glucose deprivation/reoxygenation (OGD/R) model in IEC-6 cells and a murine model of intestinal IRI were used. Nar's effects on intestinal IRI were assessed through histological analysis using H&E staining and tight junction (TJ) protein expression. Ferroptosis-related parameters, including iron levels, superoxide dismutase (SOD), glutathione (GSH), reactive oxygen species (ROS), malondialdehyde (MDA), and mitochondrial morphology, were analyzed. Network pharmacology was utilized to predict the pathways through which Nar exerts its anti-ferroptosis effects. Further mechanistic insights were obtained through si-RNA transfection, YAP inhibitor (verteporfin, VP) treatment, ferroptosis inhibitor (Ferrostatin-1) and ferroptosis inducer (Erastin) application, co-immunoprecipitation (Co-IP) and Western blotting. ResultsOur results revealed that pretreatment with Nar significantly mitigated intestinal tissue damage and improved gut barrier function, as evidenced by increased TJ proteins (ZO-1 and Occludin). Nar reduced iron, MDA, and ROS, while it increased GSH and SOD levels. Additionally, Nar alleviated mitochondrial damage in mice. Nar treatment increased GPX4 and SLC7A11, while decreasing ACSL4 levels both in vivo and in vitro. Network pharmacology analysis suggested that Nar may target the Hippo signaling pathway. Notably, YAP, a key transcriptional co-activator within the Hippo pathway, was downregulated in intestinal IRI mice and OGD/R-induced IEC-6 cells. Nar pretreatment activated YAP, thereby augmenting anti-ferroptosis effects. The inhibition of YAP activation by VP or YAP knockdown increased p-STAT3 expression, thereby diminishing Nar's efficacy. Co-IP and immunofluorescence studies confirmed the interaction between YAP and STAT3. ConclusionThis study shows that Nar can inhibit ferroptosis in intestinal IRI via activating YAP, which in turn suppresses STAT3 phosphorylation, thereby unveiling a novel mechanism and supporting Nar's potential to be a promising therapeutic agent for intestinal IRI.

Trichinellaspiralis C-type lectin mediates larva invasion of gut mucosa via binding to syndecan-1 and damaging epithelial integrity in mice

C-type lectin (CTL) plays a vital role in parasite adhesion, invading host's cells and immune escape. The objective of this research was to explore whether recombinant T. spiralis CTL (rTsCTL) binding with syndecan-1 damages intestine epithelial integrity and mediates T. spiralis intrusion in mice. The results showed that rTsCTL interacted with syndecan-1 and activated STAT3 pathway in gut epithelium, decreased tight junctions (TJs) expressions and damaged gut epithelium integrity, promoted T. spiralis intrusion, and increased expression level of inflammatory cytokine and mucin. The syndecan-1 inhibitor (β-xyloside) and STAT3 phosphorylation inhibitor (Stattic) significantly suppressed syndecan-1 expression and STAT3 pathway activation, reduced the expression levels of TJs, pro-inflammatory cytokines (TNF-α and IL-1β), Muc2 and Muc5ac, and declined intestinal permeability in T. spiralis-infected mice. These results revealed that the inhibitors suppressed T. spiralis invasion and development in gut mucosa, decreased intestinal adult burdens and relieved gut inflammation. These findings further testified that the in vivo binding of TsCTL with syndecan-1 destroyed enteral mucosal epithelial integrity and promoted T. spiralis intrusion of gut mucosa via activating STAT3 pathway and decreasing TJs expression. TsCTL could be deemed as a promising vaccine target to interrupt T. spiralis infection.

Aloperine protects the testis against testicular ischemia/reperfusion injury in rats.

Testicular torsion/detorsion can cause testis loss and infertility. Aloperine is a major active alkaloid extracted from Sophora alopecuroides Linn. It has been shown to have organ-protective effects. However, the effects of aloperine on the testis and its underlying mechanisms remain unclear. This study investigated the effect of aloperine on testicular torsion/detorsion injury in rats. Male Sprague-Dawley rats were randomized to the sham-operated (sham), testicular I/R (TI/R), or aloperine preconditioning (ALOPre) or postconditioning (ALOPost) groups. All rats except for the sham-operated rats were subjected to 3h of right spermatic cord torsion (720°, clockwise), followed by 3h of detorsion. Aloperine (10mg/kg) was intravenously administered before testicular torsion (ALOPre) or at the onset of testicular detorsion (ALOPost). The therapeutic efficacy of aloperine was evaluated by histological analysis, oxidative stress evaluation, inflammatory response examination, apoptosis analysis, protein analysis, and immunohistological assessment. Compared with TI/R, aloperine protected both the ipsilateral and contralateral testes against unilateral testicular I/R, as evidenced by a reduced testicular weight to body weight (TW/BW) ratio (ALOPre: p=0.0037; ALOPost: p=0.0021) and volume (ALOPre: p=0.0020; ALOPost: p=0.0009), less structural damage with better Johnsen (ALOPre: p=0.0013; ALOPost: p=0.0021), and Cosentino scores (ALOPre: p<0.0001; ALOPost: p<0.0001), increased mean seminiferous tubule diameter and mean seminiferous tubule epithelial height, decreased testicular apoptosis, and less oxidative stress and inflammatory response. In addition, aloperine significantly stimulated the phosphorylation of signal transducer and activator of transcription (STAT)-3 in the ipsilateral testes following detorsion. Administration of Ag490 suppressed STAT-3 phosphorylation, thereby abrogating the protective effects exerted by aloperine on the ipsilateral testis. Aloperine has a strong testicular protective effect on the ipsilateral and contralateral testes after testicular torsion/detorsion. This aloperine-induced ipsilateral testicular protection is mediated via the STAT-3 signaling pathway.

A TCM formula assists temozolomide in anti-melanoma therapy by suppressing the STAT3 signaling pathway

Ethnopharmacological relevanceTemozolomide (TMZ) is a first-line therapeutic medication for melanoma. Nonetheless, it exhibits a relatively elevated toxicity profile, and falls short in terms of both effectiveness and median survival rate. Clinical research has demonstrated that the integration of traditional Chinese medicine (TCM) with chemotherapy in the treatment of melanoma can enhance efficacy and reduce toxicity. A TCM formula (SLE) containing Lonicera japonica Thunb. and Robinia pseudoacacia L. has shown anti-melanoma properties through the inhibition of STAT3 phosphorylation. In the genesis and advancement of melanoma, the STAT3 signaling pathway is essential. Aim of the studyThe aim of this study was to evaluate the effect of SLE combined with TMZ (SLE/TMZ) in inhibiting melanoma, and to explore the contribution of inhibiting the STAT3 signaling pathway in this effect. Materials and methodsBoth A375 cells and B16F10 tumor-bearing mice were used for in vitro and in vivo experiments, respectively. In vitro assays included CCK8, crystal violet staining, flow cytometry, qRT-PCR, and Western blotting. Animal experiment indicators included tumor volume, tumor weight, mouse weight, and the proportion of mouse immune cells. ResultsSLE/TMZ inhibited the proliferation and growth of A375 cells, and also induced apoptosis. Additionally, SLE/TMZ synergistically inhibited tumor growth in the B16F10 melanoma mouse model and had immunomodulatory effects, increasing the proportion of Th, Tc, and NK cells and decreasing the proportion of MDSCs in the spleen of melanoma-bearing mice. qRT-PCR and Western blotting results confirmed that SLE/TMZ inhibited STAT3 phosphorylation and regulated its downstream factors, including Bcl2, Mcl1, CCND1, MYC, MMP2, MMP9, VEGFA, and FGF2. The inhibitory effect of SLE/TMZ on melanoma cell growth was considerably lessened when STAT3 was overexpressed at the cellular level. ConclusionSynergistic anti-melanoma effects of SLE/TMZ have been observed in animal and cellular models. One of the mechanisms of SLE/TMZ that underlies its anti-melanoma actions is inhibition of the STAT3 pathway. This work offers pre-clinical pharmacological backing for the advancement of SLE as a therapeutic agent to be used in conjunction with TMZ for the treatment of melanoma.

Parthenolide attenuates hypoxia-induced pulmonary hypertension through inhibiting STAT3 signaling

BackgroundPulmonary hypertension (PH) is a chronic lung disease characterized by the progressive pulmonary vascular remodeling with increased pulmonary arterial pressure and right ventricular failure. Pulmonary vascular remodeling involves the proliferation, migration, and resistance to apoptosis of pulmonary artery smooth cells (PASMCs). Parthenolide (PTN) is a bioactive compound derived from a traditional medical plant feverfew (Tanacetum parthenium), and it has been studied for treatment of pulmonary fibrosis, lung cancer, and other related ailments. However, the function of PTN in the treatment of PH has not been studied. PurposeThis study aimed to evaluate the anti-proliferation and pro-apoptosis effects of PTN on PH and investigate its potential mechanisms. MethodsAn in vivo hypoxia-induced pulmonary hypertension (HPH) model was established by maintaining male rats in a hypoxia chamber (10% O2) for 3 weeks, and PTN was intraperitoneally administered at the dose of 10 or 30 mg/kg. We assessed the impact of PTN on mean pulmonary arterial pressure (mPAP), pulmonary vascular remodeling, and right ventricular hypertrophy. In vitro, we evaluated hypoxia-induced cellular proliferation, migration, and apoptosis of rat PASMCs. Proteins related to the STAT3 signaling axis were analyzed by western blotting and immunofluorescence assays. Recovery experiments were performed using the STAT3 activator, colivelin TFA. ResultsPTN significantly alleviated the symptoms of HPH rats by attenuating pulmonary arterial remodeling. It also prevented the proliferation and migration of PASMCs. PTN also induced the apoptosis of PASMCs. PTN could directly interact with STAT3 and markedly inhibited STAT3 phosphorylation and nuclear translocation. In vitro, and in vivo experiments demonstrated that overexpression of STAT3 partially suppressed the effect of PTN. ConclusionOur study indicated that PTN alleviated hypoxia-induced pulmonary hypertension in rats by suppressing STAT3 activity.

Combining proteomics and Phosphoproteomics to investigate radiation-induced rectal fibrosis in rats and the effects of pSTAT3 inhibitor S3I-201 on human intestinal fibroblasts

ObjectiveTo investigate the regulatory mechanisms of radiation-induced rectal fibrosis (RIRF) and assess the therapeutic potential of S3I-201. MethodsSprague-Dawley rats were divided into control and radiation groups, with the latter exposed to 20 Gray pelvic X-rays. After 10 weeks, rectal tissues were analyzed using tandem mass tag (TMT) proteomics and phosphoproteomics. Pathway enrichment was performed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, with secondary annotation using Cluego. Representative proteins and their phosphorylated counterparts were validated through immunoblotting in another cohort. STAT3 levels in rectal tissues from irradiated and non-irradiated colorectal cancer patients were examined, and the effects of S3I-201 on human rectal fibroblasts were evaluated. ResultsThe radiation group showed significant inflammatory responses and collagen deposition in the rat rectal walls. Enrichment analysis revealed that radiation-induced proteins and phosphoproteins were primarily involved in extracellular matrix-receptor interaction and the MAPK signaling pathway. Immunoblotting indicated increased expression of p-CAMKII, p-MRACKS, p-Cfl1, p-Myl9, and p-STAT3 in the radiation group compared to the control, while p-AKT1 expression decreased. Elevated phosphorylation of STAT3 was observed in submucosal fibroblasts of the post-radiation human rectum. S3I-201 specifically inhibited STAT3 phosphorylation and suppressed activation of human rectal fibroblasts, also inhibiting the pro-fibrotic effects of the classical TGF-β/Smad/CTGF pathway. ConclusionBy integrating phosphoproteomics and proteomics, this study elucidated the protein regulatory network of RIRF and identified the potential therapeutic targets, including phosphoproteins such as STAT3 in managing RIRF. SignificanceIn our research, we employed TMT labeling alongside LC-MS/MS techniques to comprehensively explore the proteomic and phosphoproteomic landscapes in rat models of radiation-induced intestinal fibrosis (RIRF). Our analysis revealed the function and pathways of proteins and phosphorylated proteins triggered by radiation, as well as those with protective roles. We mapped a network of interactions among these proteins and validated key protein expression levels using quantitative methods. Furthermore, we investigated STAT3 as a potential therapeutic target, assessing the efficacy of the inhibitor S3I-201 in laboratory settings, and highlighting its potential for RIRF treatment. Overall, our findings provide groundbreaking insights into the mechanisms underlying RIRF, paving the way for the development of future antifibrotic therapies.

FNIP1 suppresses colorectal cancer progression through inhibiting STAT3 phosphorylation and nuclear translocation

Folliculin interacting protein 1 (FNIP1) primarily participates in regulating cellular energy metabolism and is associated with Birt-Hogg-Dubé (BHD) syndrome. Although FNIP1 has been demonstrated to function as both a tumor suppressor and promoter, its role in colorectal cancer (CRC) remains unclear. Our study demonstrated a significant downregulation of FNIP1 in CRC, correlating with shorter overall and disease-specific survival. FNIP1 may potentially serve as an independent prognostic factor in CRC. Moreover, FNIP1 inhibited CRC progression invitro and invivo. Mechanistically, FNIP1 bound to phosphorylated signal transducer and activator of transcription-3 (p-STAT3) and downregulated its expression. FNIP1 deletion increased STAT3 phosphorylation and nuclear localization, thereby promoting CRC progression. The use of p-STAT3-specific chemical inhibitors successfully mitigated excessive tumorigenesis resulting from FNIP1 absence. Thus, our results suggest that FNIP1 hinders CRC progression by suppressing STAT3 phosphorylation and nuclear translocation. FNIP1 may be a candidate prognostic indicator and a therapeutic target for intervention in CRC.

Plonmarlimab, a novel anti-GM-CSF blocking antibody, ameliorates disease progression in the pre-clinical model of macrophage activation syndrome.

We aimed to characterize and investigate the safety and efficacy of Plonmarlimab, a novel anti-granulocyte-macrophage colony-stimulating factor (anti-GM-CSF) neutralizing antibody, on the treatment of macrophage activation syndrome (MAS), a life-threatening systemic inflammatory disease, in pre-clinical models. The binding affinity was evaluated using Biacore. The neutralizing activity was measured through the blockade of ligand-receptor interaction, inhibition of STAT5 phosphorylation and suppression of TF-1 cell proliferation. The efficacy of Plonmarlimab was evaluated in a humanized MAS model, which was established by engrafting human umbilical cord blood (UCB) cells into NOG-EXL mice. Additionally, the safety profile of Plonmarlimab was investigated in cynomolgus monkeys. At the molecular level, Plonmarlimab showed sub-nanomolar binding affinity with human GM-CSF and effectively blocked the binding of GM-CSF to its receptor. At the cellular level, Plonmarlimab dose-dependently inhibited intracellular STAT5 phosphorylation and suppressed GM-CSF-induced TF-1 proliferation. In the UCB-engrafted NOG-EXL MAS mouse model, Plonmarlimab treatment significantly ameliorated disease progression, demonstrated by the improvements in body weight loss, anaemia and some histopathological features. Furthermore, Plonmarlimab was well tolerated up to 150 mg/kg weekly in monkeys with no reported adverse effects. Plonmarlimab is a highly potent GM-CSF blocking antibody and has demonstrated promising efficacy in a pre-clinical MAS model with a favourable safety profile, supporting its clinical development.

HDAC8 Enhances the Function of HIF-2α by Deacetylating ETS1 to Decrease the Sensitivity of TKIs in ccRCC.

Drug resistance after long-term use of Tyrosine kinase inhibitors (TKIs) has become an obstacle for prolonging the survival time of patients with clear cell renal cell carcinoma (ccRCC). Here, genome-wide CRISPR-based screening to reveal that HDAC8 is involved in decreasing the sensitivity of ccRCC cells to sunitinib is applied. Mechanically, HDAC8 deacetylated ETS1 at the K245 site to promote the interaction between ETS1 and HIF-2α and enhance the transcriptional activity of the ETS1/HIF-2α complex. However, the antitumor effect of inhibiting HDAC8 on sensitized TKI is not very satisfactory. Subsequently, inhibition of HDAC8 increased the expression of NEK1, and up-regulated NEK1 phosphorylated ETS1 at the T241 site to promote the interaction between ETS1 and HIF-2α by impeded acetylation at ETS1-K245 site is showed. Moreover, TKI treatment increased the expression of HDAC8 by inhibiting STAT3 phosphorylation in ccRCC cells is also found. These 2 findings highlight a potential mechanism of acquired resistance to TKIs and HDAC8 inhibitors in ccRCC. Finally, HDAC8-in-PROTACs to optimize the effects of HDAC8 inhibitors through degrading HDAC8 and overcoming the resistance of ccRCC to TKIs are synthesized. Collectively, the results revealed HDAC8 as a potential therapeutic candidate for resistance to ccRCC-targeted therapies.

Acovenosigenin A β-glucoside mediates JAK2-STAT3 signaling pathway by targeting GP130 in A549 and H460 cells based on integrative analysis of transcriptome and proteome and biological verification

Acovenosigenin A β-glucoside (AAG) is a cardiac glycoside derived from Streptocaulon juventas (Lour.) Merr, which exhibited the potential in treating lung cancer in our previous research. However, the action mechanism remains unclear. In this research, JAK2-STAT3 signaling pathway was predicted to be the critical regulation pathway based on the integrative analysis of transcriptome and proteome. Western blotting and qPCR assays were performed to identify that AAG can regulate JAK2-STAT3 signaling pathway and its downstream genes, such as c-Myc, Survivin, Cyclin B1, CDK1, Bcl-2. And this action of AAG depended on the suppression of STAT3 phosphorylation and its nuclear translocation through the experiments of Immunofluorescence, transient transfection and cryptotanshinone treatment. Additionally, AAG was discovered to mediate the JAK2-STAT3 pathway in IL-6-driven A549 and H460 cells, which in turn inhibited cell proliferation, promoted mitochondria-related apoptosis, and arrested the cell cycle progression. By molecular docking analysis, CETSA and SIP experiments, the protein of GP130 was identified as the specific target of AAG in A549 and H460 cells. Further studies suggested that AAG inhibited JAK2-STAT3 pathway and its downstream genes by targeting GP130 in nude mice xenograft model in vivo. This research presented that AAG exhibits the promising potential in the treatment of NSCLC.

Synthesis and evaluation of [18F]FBNAF, a STAT3-targeting probe, for PET imaging of tumor microenvironment

BackgroundSignal transducer and activator of transcription 3 (STAT3) is a protein that regulates cell proliferation and differentiation, and it is attracting attention as a new index for evaluating cancer pathophysiology, as its activation has been highly correlated with the development and growth of tumors. With the development of STAT3 inhibitors, the demand for imaging probes will intensify. Noninvasive STAT3 imaging can help determine the cancer status and predict the efficacy of STAT3 inhibitors. In this study, we aimed to develop an imaging probe targeting STAT3 and synthesized [18F]FBNAF, which was derived from a STAT3-selective inhibitor as the lead compound, followed by in vitro and in vivo evaluations of [18F]FBNAF in positron emission tomography for STAT3.ResultsThe results revealed that FBNAF concentration-dependently inhibited STAT3 phosphorylation, similar to the lead compound, thereby supporting radiosynthesis. [18F]FBNAF was easily synthesized from the pinacol boronate ester precursor with suitable radiochemical conversion (46%), radiochemical yield (6.0%), and radiochemical purity (> 97%). [18F]FBNAF exhibited high stability in vitro and in vivo, and radioactivity accumulated in tumor tissues expressing STAT3 with an increasing tumor/blood ratio over time, peaking at 2.6 ± 0.8 at 120 min after injection in tumor-bearing mice. Tumor radioactivity was significantly reduced by the coinjection of a STAT3-selective inhibitor. Furthermore, the localization of radioactivity was almost consistent with STAT3 expression based on ex vivo autoradiography and immunohistochemistry using adjacent tumor sections.ConclusionsThus, [18F]FBNAF could be the first promising STAT3-targeting probe for PET imaging. A STAT3 imaging probe provides meaningful information on STAT3-associated cancer conditions and in tumor microenvironment.