Exploration of novel isoxazole-fused quinone derivatives as anti-colorectal cancer agents through inhibiting STAT3 and elevating ROS level.

Colorectal cancer (CRC) is trending to be a major health problem throughout the world. Therapeutics with dual modes of action have shown latent capacity to create ideal anti-tumor activity. Signal transducer and activator of transcription 3 (STAT3) has been proved to be a potential target for the development of anti-colon cancer drug. In addition, modulation of tumor redox homeostasis through deploying exogenous reactive oxygen species (ROS)-enhancing agents has been widely applied as anti-tumor strategy. Thus, simultaneously targeting STAT3 and modulation ROS balance would offer a fresh avenue to combat CRC. In this work, we designed and synthesized a novel series of isoxazole-fused quinones, which were evaluated for their preliminary anti-proliferative activity against HCT116 cells. Among these quinones, compound 41 exerted excellent in vitro anti-tumor effect against HCT116 cell line with an IC50 value of 10.18 ± 0.4 nM. Compound 41 was proved to bind to STAT3 by using Bio-Layer Interferometry (BLI) assay, and can significantly inhibit phosphorylation of STAT3. It also elevated ROS of HCT116 cells by acting as a substrate of NQO1. Mitochondrial dysfunction, apoptosis, and cell cycle arrest, which was caused by compound 41, might be partially due to the inhibition of STAT3 phosphorylation and ROS production induced by 41. Moreover, it exhibited ideal anti-tumor activity in human colorectal cancer xenograft model and good safety profiles in vivo. Overall, this study provided a novel quinone derivative 41 with excellent anti-tumor activity by inhibiting STAT3 and elevating ROS level, and gave insights into designing novel anti-tumor therapeutics by simultaneously modulation of STAT3 and ROS.

Bone morphogenetic protein 4 derived from the cerebrospinal fluid in patients with postherpetic neuralgia induces allodynia via the crosstalk between microglia and astrocyte.

INTRODUCTION: During postherpetic neuralgia (PHN), the cerebral spinal fluid (CSF) possesses the capability to trigger glial activation and inflammation, yet the specific changes in its composition remain unclear. Recent findings from our research indicate elevations of central bone morphogenetic protein 4 (BMP4) during neuropathic pain (NP), serving as an independent modulator of glial cells. Herein, the aim of the present study is to test the CSF-BMP4 expressions and its role in the glial modulation in the process of PHN. METHODS: CSF samples were collected from both PHN patients and non-painful individuals (Control) to assess BMP4 and its antagonist Noggin levels. Besides, intrathecal administration of both CSF types was conducted in normal rats to evaluate the impact on pain behavior, glial activity, and inflammation.; Additionally, both Noggin and STAT3 antagonist-Stattic were employed to treat the PHN-CSF or exogenous BMP4 challenged cultured astrocytes to explore downstream signals. Finally, microglial depletion was performed prior to the PHN-CSF intervention so as to elucidate the microglia-astrocyte crosstalk. RESULTS: BMP4 levels were significantly higher in PHN-CSF compared to Control-CSF (P < 0.001), with a positive correlation with pain duration (P < 0.05, r = 0.502). Comparing with the Control-CSF producing moderate paw withdrawal threshold (PWT) decline and microglial activation, PHN-CSF further exacerbated allodynia and triggered both microglial and astrocytic activation (P < 0.05). Moreover, PHN-CSF rather than Control-CSF evoked microglial proliferation and pro-inflammatory transformation, reinforced iron storage, and activated astrocytes possibly through both SMAD159 and STAT3 signaling, which were all mitigated by the Noggin application (P < 0.05). Next, both Noggin and Stattic effectively attenuated BMP4-induced GFAP and IL-6 upregulation, as well as SMAD159 and STAT3 phosphorylation in the cultured astrocytes (P < 0.05). Finally, microglial depletion diminished PHN-CSF induced astrogliosis, inflammation and endogenous BMP4 expression (P < 0.05). CONCLUSION: Our study highlights the role of CSF-BMP4 elevation in glial activation and allodynia during PHN, suggesting a potential therapeutic avenue for future exploration.

Prognostic and therapeutic potential of STAT3: Opportunities and challenges in targeting HPV-mediated cervical carcinogenesis.

Cervical cancer (CaCx) ranks as the fourth most prevalent cancer among women globally. Persistent infection of high-risk human papillomaviruses (HR-HPVs) is major etiological factor associated with CaCx. Signal Transducer and Activator of Transcription 3 (STAT3), a prominent member of the STAT family, has emerged as independent oncogenic driver. It is a target of many oncogenic viruses including HPV. How STAT3 influences HPV viral gene expression or gets affected by HPV is an area of active investigation. A better understanding of host-virus interaction will provide a prognostic and therapeutic window for CaCx control and management. In this comprehensive review, we delve into carcinogenic role of STAT3 in development of HPV-induced CaCx. With an emphasis on fascinating interplay between STAT3 and HPV genome, the review explores the diverse array of opportunities and challenges associated with this field to harness the prognostic and therapeutic potential of STAT3 in CaCx.

Ubiquitin ligase MDM2 mediates endothelial inflammation in Kawasaki disease vasculitis development.

Background: Kawasaki disease (KD) often complicates coronary artery lesions (CALs). Despite the established significance of STAT3 signaling during the acute phase of KD and signal transducer and activator of transcription 3 (STAT3) signaling being closely related to CALs, it remains unknown whether and how STAT3 was regulated by ubiquitination during KD pathogenesis. Methods: Bioinformatics and immunoprecipitation assays were conducted, and an E3 ligase, murine double minute 2 (MDM2) was identified as the ubiquitin ligase of STAT3. The blood samples from KD patients before and after intravenous immunoglobulin (IVIG) treatment were utilized to analyze the expression level of MDM2. Human coronary artery endothelial cells (HCAECs) and a mouse model were used to study the mechanisms of MDM2-STAT3 signaling during KD pathogenesis. Results: The MDM2 expression level decreased while the STAT3 level and vascular endothelial growth factor A (VEGFA) level increased in KD patients with CALs and the KD mouse model. Mechanistically, MDM2 colocalized with STAT3 in HCAECs and the coronary vessels of the KD mouse model. Knocking down MDM2 caused an increased level of STAT3 protein in HCAECs, whereas MDM2 overexpression upregulated the ubiquitination level of STAT3 protein, hence leading to significantly decreased turnover of STAT3 and VEGFA. Conclusions: MDM2 functions as a negative regulator of STAT3 signaling by promoting its ubiquitination during KD pathogenesis, thus providing a potential intervention target for KD therapy.

Langat virus inhibits the gp130/JAK/STAT signaling by reducing the gp130 protein level.

The tick-borne encephalitis virus (TBEV) serocomplex includes several medically important flavivirus members endemic to Europe, Asia, and North America, which can induce severe neuroinvasive or viscerotropic diseases with unclear mechanisms of pathogenesis. Langat virus (LGTV) shares a high sequence identity with TBEV but exhibits lower pathogenic potential in humans and serves as a model for virus-host interactions. In this study, we demonstrated that LGTV infection inhibits the activation of gp130/JAK/STAT (Janus kinases (JAK) and signal transducer and activator of transcription (STAT)) signaling, which plays a pivotal role in numerous biological processes. Our data show that the LGTV-infected cells had significantly lower phosphorylated STAT3 (pSTAT3) protein upon oncostatin M (OSM) stimulation than the mock-infected control. LGTV infection blocked the nuclear translocation of STAT3 without a significant effect on total STAT3 protein level. LGTV inhibited JAK1 activation and reduced gp130 protein expression in infected cells, with the viral NS5 protein mediating this effect. TBEV infection also reduces gp130 level. On the other hand, pretreatment of Vero cells with OSM significantly reduces LGTV replication, and STAT1/STAT2 knockdown had little effect on OSM-mediated antiviral effect, which suggests it is independent of STAT1/STAT2 and, instead, it is potentially mediated by STAT3 signlaing. These findings shed light on the LGTV and TBEV-cell interactions, offering insights for the future development of antiviral therapeutics and improved vaccines.

[Molecular Mechanism-based Prediction of Interstitial Lung Disease Development Causedby Molecular Targeted Drugs: Association between Signal Transducer and Activator of Transcription 3 and Mammalian Target of Rapamycin inhibitor-induced Interstitial Lung Disease].

Interstitial lung disease (ILD) is a serious adverse event common to many molecular targeted anticancer drugs. The development of ILD significantly reduces the QOL of patients and results in treatment discontinuation. Because the development of ILD is also associated with therapeutic efficacy, the establishment of prediction strategies for ILD is important. We have focused on signal transducer and activator of transcription 3 (STAT3) as an important mechanistic factor in ILD induced by molecular targeted drugs. Our study aimed to establish mechanism-based ILD prediction strategies; therefore, we investigated the hypothesis that a genetic polymorphism in STAT3 is a predictive factor of the incidence of ILD induced by mammalian target of rapamycin (mTOR) inhibitors, a class of molecular targeted drugs associated with a higher incidence of ILD. Our clinical study clearly demonstrated that the rate of ILD induced by mTOR inhibitors was significantly higher in patients with the G allele homozygous genotype of STAT3 -1697C>G compared with those with other genotypes. The cumulative incidence of ILD in patients with the G allele homozygous genotype was significantly higher compared with that in patients carrying other genotypes. Furthermore, our in vitro study indicated that the epithelial-to-mesenchymal transition (EMT), a pre-process of tissue fibrosis, was induced by an mTOR inhibitor in lung alveolar epithelial cell lines carrying the G allele homozygous genotype which was associated with a higher risk of ILD. Our study provided a novel predictive strategy for the development of ILD induced by molecular targeted drugs.

Arctiin Inhibits Inflammation, Fibrosis, and Tumor Cell Migration in Rats With Ehrlich Solid Carcinoma.

BACKGROUND AND OBJECTIVES: ESC or Ehrlich solid carcinoma is a type of tumor originating from a spontaneous mammary adenocarcinoma in mice. It is a highly aggressive and fast-growing carcinoma that can create a solid mass when inserted under the skin. Its solid, undifferentiated form makes it an ideal model for researching cancer biology, tumor immunology, and testing various anti-cancer treatments. Additionally, arctiin has multiple beneficial properties, such as anti-proliferative, anti-oxidative, anti-adipogenic, and anti-bacterial. This study aimed to explore the potential anti-cancer benefits of arctiin in rats with ESC while also analyzing its effects on cell fibrosis markers, tumor cell migration, and inflammasome pathways. METHODS: Rats were given a tumor in their left hind limb via an intramuscular injection consisting of 2×106 cells. After eight days, some of the rats received a daily oral dose of 30 mg/kg of arctiin for three weeks. Muscle samples were observed under an electron microscope or stained with hematoxylin/eosin. Additionally, gene expression and protein levels of toll-like receptor 4 (TLR4), NLR family pyrin domain containing 3 (NLRP3), signal transducer and activator of transcription 3 (STAT3), transforming growth factor (TGF)-ß, endothelial growth factor (VEGF), and cyclin D1 were assessed in another part of the muscle samples. RESULTS: When ESC rats were given arctiin as a treatment, their mean survival time increased and their tumor volume and weight decreased. Additionally, when tumor tissue was examined under an electron microscope, it showed signs of pleomorphic cells, necrosis, nuclear fragmentation, membrane damage with cytoplasmic content spilling, and loss of cellular junction. The stained sections with hematoxylin/eosin showed a dense cellular mass and compressed, degenerated, and atrophied muscle. However, treatment with arctiin improved all these effects. Finally, the expression of TLR4, NLRP3, STAT3, TGF-ß, VEGF, and cyclin D1 was significantly reduced with arctiin treatment. CONCLUSIONS: Through the use of arctiin, tumor size and weight were effectively reduced, leading to an increase in the average survival time of rats and an improvement in muscle structure. Additional research has shown that arctiin is able to suppress inflammation, fibrosis, and the migration of tumor cells by inhibiting STAT3, TGF-ß1, TLR4, NLRP3, VEGF, and cyclin D1.

Physical interaction between STAT3 and AP1 in cervical carcinogenesis: Implications in HPV transcription control.

The constitutive activation and aberrant expression of Signal Transducer and Activator of Transcription 3 (STAT3) plays a key role in initiation and progression of cervical cancer (CaCx). How STAT3 influences HPV transcription is poorly defined. In the present study, we probed direct and indirect interactions of STAT3 with HPV16/18 LCR. In silico assessment of cis-elements present on LCR revealed the presence of potential STAT3 binding motifs. However, experimental validation by ChIP-PCR could not confirm any specific STAT3 binding on HPV16 LCR. Protein-protein interaction (PPI) network analysis of STAT3 with other host transcription factors that bind LCR, highlighted the physical association of STAT3 with c-FOS and c-JUN. This was further confirmed in vitro by co-immunoprecipitation, where STAT3 co-immunoprecipitated with c-FOS and c-JUN in CaCx cells. The result was supported by immunocytochemical analysis and colocalization of STAT3 with c-FOS and c-JUN. Positive signals in proximity ligation assay validated physical interaction and colocalization of STAT3 with AP1. Colocalization of STAT3 with c-FOS and c-JUN increased upon IL-6 treatment and decreased post-Stattic treatment. Alteration of STAT3 expression affected the subcellular localization of c-FOS and c-JUN, along with the expression of viral oncoproteins (E6 and E7) in CaCx cells. High expression of c-JUN in tumor tissues correlated with poor prognosis in both HPV16 and HPV18 CaCx cohort whereas high expression of STAT3 correlated with poor prognosis in HPV18 CaCx lesions only. Overall, the data suggest an indirect interaction of STAT3 with HPV LCR via c-FOS and c-JUN and potentiate transcription of viral oncoproteins.

The Role of STAT3 Signaling Pathway Activation in Subconjunctival Scar Formation after Glaucoma Filtration Surgery.

Scar formation resulting from overly active wound healing is a critical factor in the success rate of glaucoma filtration surgery (GFS). IL-6 and TGF-ß have been implicated in the pathogenesis of fibrogenesis. In addition, the signal transducer and activator of transcription 3 (STAT3) can be activated by numerous cytokines and growth factors, including IL-6 and TGF-ß1. Thus, STAT3 activation may integrate common profibrotic pathways to promote fibrosis. In this study, an increase in p-STAT3 was observed in activated HTFs. Inhibiting STAT3 in cultured HTFs by pharmacological inactivation reversed the fibrotic responses, such as fibroblast migration, the differentiation of resting fibroblasts into myofibroblasts and the deposition of ECM, mediated by IL-6 and TGF-ß1. Moreover, the expression of suppressor of cytokine signaling 3 (SOCS3) was decreased in HTFs cultured with IL-6 and TGF-ß1, and SOCS3 overexpression rescued ECM deposition, α-SMA expression and migration in IL-6- and TGF-ß1-stimulated HTFs by inactivating STAT3. Finally, S3I-201 treatment inhibited profibrotic gene expression and subconjunctival fibrosis in a rat model of GFS. In conclusion, our data suggests that STAT3 plays a central role in fibrosis induced by different profibrotic pathways and that STAT3 is a potential target for antifibrotic therapies following GFS.

Antitumor Activity of Ferulic Acid Against Ehrlich Solid Carcinoma in Rats via Affecting Hypoxia, Oxidative Stress and Cell Proliferation.

Background Ferulic acid is a natural compound commonly found in fruits and vegetables like tomatoes, sweet corn, rice bran, and dong quai. It has various beneficial effects on the body, such as anti-inflammatory, anti-apoptotic, hepatoprotective, cardioprotective, and neuroprotective properties. Aims We conducted a study to investigate the antitumor activity of ferulic acid against Ehrlich solid carcinoma (ESC), specifically by affecting hypoxia-inducible factor (HIF)-1α and its subsequent effects on other factors like nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), cellular Myc (cMyc), cyclin D1, mammalian target of rapamycin (mTOR), and signal transducer and activator of transcription 3 (STAT3). Materials and methods The study involved implanting rats with ESC cells and administering 50 mg/kg of ferulic acid orally daily for eight days. Sections of the muscles with ESC were stained with toluidine blue or immunostained with anti-HIF-1α antibodies. The tumor samples were used to evaluate the expression of HIF-1α, Nrf2, HO-1, cMyc, cyclin D1, mTOR, and STAT3. Results Ferulic acid increased mean survival time, reduced tumor volume and weight, and improved the appearance of the tumor tissue. Furthermore, ferulic acid significantly elevated the expression of Nrf2 and HO-1, while reducing the expression of HIF-1α, Nrf2, HO-1, cMyc, cyclin D1, mTOR, and STAT3. Conclusions Ferulic acid can reduce tumor size and weight while improving the structure of muscle cells, suggesting it may have antineoplastic activity against ESC. Further investigation revealed that ferulic acid downregulates HIF-1α, increasing the expression of antioxidant proteins Nrf2 and HO-1. Additionally, ferulic acid decreases the expression of proliferation markers cMyc and cyclin D1 and downregulates cellular regulators mTOR and STAT3.

CD109 Promotes Drug Resistance in A2780 Ovarian Cancer Cells by Regulating the STAT3-NOTCH1 Signaling Axis.

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy owing to relapse caused by resistance to chemotherapy. We previously reported that cluster of differentiation 109 (CD109) expression is positively correlated with poor prognosis and chemoresistance in patients with EOC. To further explore the role of CD109 in EOC, we explored the signaling mechanism of CD109-induced drug resistance. We found that CD109 expression was upregulated in doxorubicin-resistant EOC cells (A2780-R) compared with that in their parental cells. In EOC cells (A2780 and A2780-R), the expression level of CD109 was positively correlated with the expression level of ATP-binding cassette (ABC) transporters, such as ABCB1 and ABCG2, and paclitaxel (PTX) resistance. Using a xenograft mouse model, it was confirmed that PTX administration in xenografts of CD109-silenced A2780-R cells significantly attenuated in vivo tumor growth. The treatment of CD109-overexpressed A2780 cells with cryptotanshinone (CPT), a signal transducer and activator of transcription 3 (STAT3) inhibitor, inhibited the CD109 overexpression-induced activation of STAT3 and neurogenic locus notch homolog protein 1 (NOTCH1), suggesting a STAT3-NOTCH1 signaling axis. The combined treatment of CD109-overexpressed A2780 cells with CPT and N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT), a NOTCH inhibitor, markedly abrogated PTX resistance. These results suggest that CD109 plays a key role in the acquisition of drug resistance by activating the STAT3-NOTCH1 signaling axis in patients with EOC.

Neuronal growth regulator 1 may modulate interleukin-6 signaling in adipocytes.

Interleukin-6 (IL-6) is a pleiotropic cytokine that plays both anti- and pro-inflammatory roles. Due to the restricted expression of membrane IL-6 receptor (IL-6R), most pro-inflammatory functions of IL-6 are attributed to its association with soluble IL-6R (sIL-6R). Neuronal growth regulator 1 (NEGR1) is a brain-enriched membrane protein that has recently been recognized as a risk factor for many human diseases including obesity, depression, and autism. In the present study, we report that the expression levels of IL-6 and IL-6R, as well as the phosphorylation of signal transducer and activator of transcription (STAT) 3, were significantly elevated in white adipose tissues of Negr1 knockout mice. Elevated levels of circulating IL-6 and sIL-6R have also been observed in Negr1 -/- mice. Furthermore, NEGR1 interacted with IL-6R, which was supported by subcellular fractionation and an in situ proximity ligation assay. Importantly, NEGR1 expression attenuated the phosphorylation of STAT3 by sIL-6R, suggesting that NEGR1 negatively regulates IL-6 trans-signaling. Taken together, we propose that NEGR1 may play a regulatory role in IL-6 signaling by interacting with IL-6R, which may contribute to a molecular link underlying obesity, inflammation, and the depression cycle.

Src-FAK Signaling Mediates Interleukin 6-Induced HCT116 Colorectal Cancer Epithelial-Mesenchymal Transition.

Colorectal cancer is one of the most prevalent and lethal malignancies, affecting approximately 900,000 individuals each year worldwide. Patients with colorectal cancer are found with elevated serum interleukin-6 (IL-6), which is associated with advanced tumor grades and is related to their poor survival outcomes. Although IL-6 is recognized as a potent inducer of colorectal cancer progression, the detail mechanisms underlying IL-6-induced colorectal cancer epithelial-mesenchymal transition (EMT), one of the major process of tumor metastasis, remain unclear. In the present study, we investigated the regulatory role of IL-6 signaling in colorectal cancer EMT using HCT116 human colorectal cancer cells. We noted that the expression of epithelial marker E-cadherin was reduced in HCT116 cells exposed to IL-6, along with the increase in a set of mesenchymal cell markers including vimentin and α-smooth muscle actin (α-SMA), as well as EMT transcription regulators-twist, snail and slug. The changes of EMT phenotype were related to the activation of Src, FAK, ERK1/2, p38 mitogen-activated protein kinase (p38MAPK), as well as transcription factors STAT3, κB and C/EBPß. IL-6 treatment has promoted the recruitment of STAT3, κB and C/EBPß toward the Twist promoter region. Furthermore, the Src-FAK signaling blockade resulted in the decline of IL-6 induced activation of ERK1/2, p38MAPK, κB, C/EBPß and STAT3, as well as the decreasing mesenchymal state of HCT116 cells. These results suggested that IL-6 activates the Src-FAK-ERK/p38MAPK signaling cascade to cause the EMT of colorectal cancer cells. Pharmacological approaches targeting Src-FAK signaling may provide potential therapeutic strategies for rescuing colorectal cancer progression.

Identification of marine natural product Pretrichodermamide B as a STAT3 inhibitor for efficient anticancer therapy.

The Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) regulates the expression of various critical mediators of cancer and is considered as one of the central communication nodes in cell growth and survival. Marine natural products (MNP) represent great resources for discovery of bioactive lead compounds, especially anti-cancer agents. Through the medium-throughput screening of our in-house MNP library, Pretrichodermamide B, an epidithiodiketopiperazine, was identified as a JAK/STAT3 signaling inhibitor. Further studies identified that Pretrichodermamide B directly binds to STAT3, preventing phosphorylation and thus inhibiting JAK/STAT3 signaling. Moreover, it suppressed cancer cell growth, in vitro, at low micromolar concentrations and demonstrated efficacy in vivo by decreasing tumor growth in a xenograft mouse model. In addition, it was shown that Pretrichodermamide B was able to induce cell cycle arrest and promote cell apoptosis. This study demonstrated that Pretrichodermamide B is a novel STAT3 inhibitor, which should be considered for further exploration as a promising anti-cancer therapy. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-022-00162-x.

Butein Inhibits Cell Growth by Blocking the IL-6/IL-6Rα Interaction in Human Ovarian Cancer and by Regulation of the IL-6/STAT3/FoxO3a Pathway.

Butea monosperma (Fabaceae) has been used in traditional Indian medicine to treat a variety of ailments, including abdominal tumors. We aimed to investigate the anti-IL-6 activity of butein in ovarian cancer and elucidate the underlying molecular mechanisms. Butein was isolated and identified from B. monosperma flowers, and the inhibition of IL-6 signaling was investigated using the HEK-Blue™ IL-6 cell line. The surface plasmon resonance assay was used to estimate the binding of butein to IL-6, IL-6Rα, and gp130. After treatment with butein, ovarian cancer cell migration, apoptosis, and tumor growth inhibition were evaluated in vitro and in vivo. Furthermore, we used STAT3 siRNA to identify the mechanistic effects of butein on the IL-6/STAT3/FoxO3a pathway. Butein suppressed downstream signal transduction through higher binding affinity to IL-6. In ovarian cancer, butein inhibited cell proliferation, migration, and invasion, and induced cell cycle arrest and apoptosis. In addition, it decreased the growth of ovarian cancer cells in xenograft tumor models. Butein inhibited STAT3 phosphorylation and induced FoxO3a accumulation in the nucleus by inhibiting IL-6 signaling. The anticancer activity of butein was mediated by blocking the IL-6/IL-6Rα interaction and suppressing IL-6 bioactivity via interfering with the IL-6/STAT3/FoxO3a pathway.

The Physiological and Pathophysiological Role of IL-6/STAT3-Mediated Signal Transduction and STAT3 Binding Partners in Therapeutic Applications.

The interleukin 6 (IL-6) family of cytokines is defined by the usage of gp130, a common ß-receptor signaling subunit, which promotes a variety of signals. They induce many biological functions on many cell types, including immune and inflammatory cells. They also exhibit hormone-like features, which are involved in homeostatic processes. Signal transducer and activator of transcription 3 (STAT3) is a significant signaling molecule fundamental in regulating IL-6/gp130 and is highly implicated in pathological conditions; therefore, STAT3 activation is tightly regulated through various mechanisms and at multiple levels. There is a large amount of information about STAT3-interacting proteins, which positively or negatively regulate STAT3 activity. This review is focused on IL-6-mediated signal transduction and the introduction of novel STAT3-binding partners. The review will help develop new strategies for clinically controlling the functions of IL-6/STAT3.

Multi-Omics Profiling in PGM3 and STAT3 Deficiencies: A Tale of Two Patients.

Hyper-IgE Syndrome (HIES) is a heterogeneous group of primary immune-deficiency disorders characterized by elevated levels of IgE, eczema, and recurrent skin and lung infections. HIES that is autosomally dominant in the signal transducer and activator of transcription 3 (STAT3), and autosomal recessive mutations in phosphoglucomutase 3 (PGM3) have been reported in humans. An early diagnosis, based on clinical suspicion and immunological assessments, is challenging. Patients' metabolomics, proteomics, and cytokine profiles were compared to DOCK 8-deficient and atopic dermatitis patients. The PGM3 metabolomics profile identified significant dysregulation in hypotaurine, hypoxanthine, uridine, and ribothymidine. The eight proteins involved include bifunctional arginine demethylase and lysyl hydroxylase (JMJD1B), type 1 protein phosphatase inhibitor 4 (PPI 4), and platelet factor 4 which aligned with an increased level of the cytokine GCSF. Patients with STAT3 deficiency, on the other hand, showed significant dysregulation in eight metabolites, including an increase in protocatechuic acid, seven proteins including ceruloplasmin, and a plasma protease C1 inhibitor, in addition to cytokine VEGF being dysregulated. Using multi-omics profiling, we identified the dysregulation of endothelial growth factor (EGFR) and tumor necrosis factor (TNF) signaling pathways in PGM3 and STAT3 patients, respectively. Our findings may serve as a stepping stone for larger prospective HIES clinical cohorts to validate their future use as biomarkers.

Osteoblastic STAT3 Is Crucial for Orthodontic Force Driving Alveolar Bone Remodeling and Tooth Movement.

Mechanical force is essential to shape the internal architecture and external form of the skeleton by regulating the bone remodeling process. However, the underlying mechanism of how the bone responds to mechanical force remains elusive. Here, we generated both orthodontic tooth movement (OTM) model in vivo and a cyclic stretch-loading model in vitro to investigate biomechanical regulation of the alveolar bone. In this study, signal transducer and activator of transcription 3 (STAT3) was screened as one of the mechanosensitive proteins by protein array analysis of cyclic stretch-loaded bone mesenchymal stem cells (BMSCs) and was also proven to be activated in osteoblasts in response to the mechanical force during OTM. With an inducible osteoblast linage-specific Stat3 knockout model, we found that Stat3 deletion decelerated the OTM rate and reduced orthodontic force-induced bone remodeling, as indicated by both decreased bone resorption and formation. Both genetic deletion and pharmacological inhibition of STAT3 in BMSCs directly inhibited mechanical force-induced osteoblast differentiation and impaired osteoclast formation via osteoblast-osteoclast cross-talk under mechanical force loading. According to RNA-seq analysis of Stat3-deleted BMSCs under mechanical force, matrix metalloproteinase 3 (Mmp3) was screened and predicted to be a downstream target of STAT3. The luciferase and ChIP assays identified that Stat3 could bind to the Mmp3 promotor and upregulate its transcription activity. Furthermore, STAT3-inhibitor decelerated tooth movement through inhibition of the bone resorption activity, as well as MMP3 expression. In summary, our study identified the mechanosensitive characteristics of STAT3 in osteoblasts and highlighted its critical role in force-induced bone remodeling during orthodontic tooth movement via osteoblast-osteoclast cross-talk. © 2022 American Society for Bone and Mineral Research (ASBMR).

Role of LIF/LIFR/STAT3 pathway in endometrial receptivity in rats with polycystic ovary syndrome / 西安交通大学学报(医学版)

【Objective】 To investigate the role of LIF/LIFR/STAT3 pathway in endometrial receptivity in rats with polycystic ovary syndrome (PCOS). 【Methods】 Forty 21-day-old SD female rats were divided into normal (control) group, model group, sham-operation group, and LIF group with 10 rats in each. The rat model of PCOS was constructed by subcutaneous injection of prasterone sodium sulfate at the back of the neck. The serum levels of testosterone (T), glucose and insulin in each group were detected. The morphological changes of the uterus in each group were observed by HE staining, and the morphological changes of endometrium were measured. Immunohistochemistry, Western blotting, and Real-time fluorescence quantitative PCR(qRT-PCR) were used to determine the protein expression and mRNA expression of LIF and STAT3 in rat endometrium. 【Results】 Compared with control group, the levels of integrin avb3, serum T, insulin and glucose in PCOS rats were significantly increased (P=0.000, P=0.000, P=0.001). Supplementation of exogenous LIF could significantly reduce the levels of integrin avb3, serum T, glucose and insulin in PCOS rats (P=0.000, P=0.002, P=0.003, P=0.007). HE results showed that exogenous LIF could reduce uterine cavity and glandular morphology in PCOS rats and increase the equivalent diameter (P=0.000, P=0.000) and area (P=0.000, P=0.000) of uterine glands and glandular cavity, the ratio of glandular interstitial area (P=0.000), and the average endometrial thickness (P=0.006), with statistically significant differences. Immunohistochemistry, Western blotting, and qRT-PCR results showed that the expression levels of LIF and p-STAT3 protein and mRNA in model group were significantly decreased compared with control group. Compared with model group, the protein and mRNA expressions of LIF and p-STAT3 in LIF group were significantly increased (P<0.05). 【Conclusion】 Exogenous LIF supplementation can improve endometrial receptivity in PCOS rats, and its mechanism is related to the LIF/LIFR/STAT3 pathway.

Interleukin-6 in Skeletal Muscle Mass Regulation / 中国生物化学与分子生物学报

Interleukin-6 (IL-6) is a spreading pleiotropic cytokine, with both anti-inflammatory and proinflammatory effects. It not only participates in the body immune responses but also is involved in the biological regulative processes among different organs, tissues, and cells. IL-6 has both anti-inflammatory and pro-inflammatory effects. In the early stage of pathogen infection, IL-6 plays an anti-inflammatory role in the body, and its level is moderately increased in the body to resist inflammation and maintain internal homeostasis. However, a large amount of IL-6 release can cause excessive inflammation and trigger other pathological changes in the body. Il-6 also has the dual effect of stimulating the synthesis and degradation of skeletal muscle protein in regulating skeletal muscle mass. As an important locomotive organ, skeletal muscle is also one of the key targets of IL-6. IL-6 takes part in the biological control of skeletal muscle hypertrophy through regulating muscle satellite cell proliferation and differentiation under specific stresses. In addition IL-6 is also associated with skeletal muscle atrophy induced by aging and other pathological stresses. In addition, during exercise stress, skeletal muscle can also serve as an endocrine organ to secrete and release IL-6 that facilitates the "crosstalk" between skeletal muscle and other organs or tissues. As IL-6 plays as a versatile role in our body, this paper reviews the research progress of the mechanism of IL-6 in the regulation of skeletal muscle mass, which may provide theoretical support for revealing the molecular mechanism of skeletal muscle stresses and adaptations.