Signal Transducer And Activator Of Transcription Proteins Research Articles

Unraveling the Immunogenetics of STAT Proteins: Clinical Perspectives on Gain-of-Function and Loss-of-Function Variants.

Signal Transducer and Activator of Transcription (STAT) proteins play pivotal roles in immune regulation. The dysregulation of these proteins, attributed to both gain-of-function (GOF) and loss-of-function (LOF) variants, has emerged as a substantial and intricate area of research. This comprehensive review delves into the intricate details of the diverse clinical spectrum associated with STAT variants and the immunological findings linked to these genetic alterations. Although this review does not encompass the treatment of each individual disease, we discuss investigative approaches ranging from immunophenotyping assessment to evaluation of STAT protein activity. These investigations play a crucial role in identifying affected patients and understanding the complexities of STAT.

Novel STAT3 oligonucleotide compounds suppress tumor growth and overcome the acquired resistance to sorafenib in hepatocellular carcinoma.

Signal transducer and activator of transcription 3 (STAT3) plays an important role in the occurrence and progression of tumors, leading to resistance and poor prognosis. Activation of STAT3 signaling is frequently detected in hepatocellular carcinoma (HCC), but potent and less toxic STAT3 inhibitors have not been discovered. Here, based on antisense technology, we designed a series of stabilized modified antisense oligonucleotides targeting STAT3 mRNA (STAT3 ASOs). Treatment with STAT3 ASOs decreased the STAT3 mRNA and protein levels in HCC cells. STAT3 ASOs significantly inhibited the proliferation, survival, migration, and invasion of cancer cells by specifically perturbing STAT3 signaling. Treatment with STAT3 ASOs decreased the tumor burden in an HCC xenograft model. Moreover, aberrant STAT3 signaling activation is one of multiple signaling pathways involved in sorafenib resistance in HCC. STAT3 ASOs effectively sensitized resistant HCC cell lines to sorafenib in vitro and improved the inhibitory potency of sorafenib in a resistant HCC xenograft model. The developed STAT3 ASOs enrich the tools capable of targeting STAT3 and modulating STAT3 activity, serve as a promising strategy for treating HCC and other STAT3-addicted tumors, and alleviate the acquired resistance to sorafenib in HCC patients. A series of novel STAT3 antisense oligonucleotide were designed and showed potent anti-cancer efficacy in hepatocellular carcinoma in vitro and in vivo by targeting STAT3 signaling. Moreover, the selected STAT3 ASOs enhance sorafenib sensitivity in resistant cell model and xenograft model.

Identification and characterization of STAT family in silver pomfret (Pampus argenteus) involved in different exogenous stresses

Members of the Signal Transducer and Activator of Transcription (STAT) family function pivotally as transcriptional activators integral to the modulation of inflammatory responses. The aquaculture of silver pomfret is frequently compromised by the imposition of exogenous stressors, which include thermal fluctuations, notably low-temperatures, diminished oxygen levels, and the onslaught of bacterial pathogens. Notwithstanding the critical impact of these stressors, the scientific literature presents a notable gap in our understanding of the STAT pathway's role in the silver pomfret's adaptive response mechanisms. To address this lacuna, we identified stat genes in the silver pomfret—denominated as Pastat1, Pastat2, Pastat3, Pastat4, and Pastat5—through a thorough and systematic bioinformatics analysis. Further scrutiny of the gene configurations and constituent motifs has elucidated that STAT proteins possess analogous structural frameworks and exhibit significant evolutionary preservation. Subsequently, the expression patterns of five stat genes were verified by RT-qPCR in twelve different tissues and four growth periods in healthy fish, showing that the expression of Pastat genes was temporally and spatially specific, with most of the stat genes expressed at higher levels in the spleen, following muscle, gill, and liver. Transcriptomic analysis of exposure to exogenous stressors, specifically formaldehyde and low-temperature conditions, elucidated that Pastat1 and Pastat2 genes exhibited a heightened sensitivity to these environmental challenges. RT-qPCR assays demonstrated a marked alteration in the expression profiles of jak1 and Pastat gene suites in PaS upon prolonged bacterial infection subsequent to these exogenous insults. Moreover, the gene expression of the downstream effectors involved in innate immunity and apoptosis displayed marked deviations. This study additionally elucidated the Pastat gene family's role in modulating the innate immune response and apoptotic regulation within the silver pomfret during exogenous stressors and subsequent pathogenic incursions.

Oncogenic STAT Transcription Factors as Targets for Cancer Therapy: Innovative Strategies and Clinical Translation.

Despite advances in our understanding of molecular aspects of oncogenesis, cancer remains a leading cause of death. The malignant behavior of a cancer cell is driven by the inappropriate activation of transcription factors. In particular, signal transducers and activators of transcription (STATs), which regulate many critical cellular processes such as proliferation, apoptosis, and differentiation, are frequently activated inappropriately in a wide spectrum of human cancers. Multiple signaling pathways converge on the STATs, highlighting their importance in the development and progression of oncogenic diseases. STAT3 and STAT5 are two members of the STAT protein family that are the most frequently activated in cancers and can drive cancer pathogenesis directly. The development of inhibitors targeting STAT3 and STAT5 has been the subject of intense investigations in the last decade, although effective treatment options remain limited. In this review, we investigate the specific roles of STAT3 and STAT5 in normal physiology and cancer biology, discuss the opportunities and challenges in pharmacologically targeting STAT proteins and their upstream activators, and offer insights into novel therapeutic strategies to identify STAT inhibitors as cancer therapeutics.

STAT protein family and cardiovascular diseases: overview of pathological mechanisms and therapeutic implications.

Globally, cardiovascular diseases (CVD) are one of the significant causes of death and are considered a major concern of human society. One of the most crucial objectives of scientists is to reveal the mechanisms associated with the pathogenesis of CVD, which has attracted the attention of many scientists. Accumulating evidence showed that the signal transducer and activator of transcription (STAT) signaling pathway is involved in various physiological and pathological processes. According to research on the molecular mechanisms of CVDs, the STAT family of proteins is one of the most crucial players in these diseases. Numerous studies have demonstrated the undeniable relevance of STAT family proteins in various CVDs. The aim of this review is to shed light on how STAT signaling pathways are related to CVD and the potential for using these signaling pathways as therapeutic targets.

Abstract 6539: RNAi mediated silencing of STAT3 in tumor-associated immune cells induces robust anti-tumor effects in immunotherapy resistant tumors

Abstract Malignant tumors are often associated with an immunosuppressive tumor microenvironment (TME), rendering most of them resistant to standard-of-care immune checkpoint inhibitors (CPIs). Signal transducer and activator of transcription 3 (STAT3), a ubiquitously expressed transcription factor, has well-defined immunosuppressive functions in several leukocyte populations within the TME. Since the STAT3 protein has been challenging to target using conventional pharmaceutical modalities, we investigated the feasibility of applying systemically delivered RNA interference (RNAi) agents to silence its mRNA directly in tumor-associated immune cells. In preclinical murine tumor models, chemically stabilized acetylated small-interfering RNAs (siRNAs) selectively silenced Stat3 mRNA in multiple relevant cell types in TME and tumor-draining lymph nodes (TDLN), reduced STAT3 protein levels, and increased cytotoxic T-cell infiltration. In murine models of CPI-resistant tumors, RNAi-mediated Stat3 silencing resulted in tumor growth inhibition, which was further enhanced and resulted in tumor regressions in combination with CPIs. Our findings suggest that targeting STAT3 directly and reducing STAT3 protein in the suppressive immune cell populations in the TME and TDLN may overcome some of the current limitations of immunotherapy and be of therapeutic benefit especially for cancer patients who failed to respond to standard immunotherapy treatments alone. A human active STAT3 conjugate is currently in Phase 1 clinical trial for treatment of immunotherapy refractory cancer types (NCT06098651). Citation Format: Shanthi Ganesh, Minju Kim, Jenny Lee, Xudong Feng, Harini Sivagurunatha Krishnan, Rene Rijnbrand, Amber Beaudry, Jennifer A. Lockridge, Vinita Uttamsingh, John Hanrahan. RNAi mediated silencing of STAT3 in tumor-associated immune cells induces robust anti-tumor effects in immunotherapy resistant tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6539.

RNAi mediated silencing of STAT3/PD-L1 in tumor-associated immune cells induces robust anti-tumor effects in immunotherapy resistant tumors

Malignant tumors are often associated with an immunosuppressive tumor microenvironment (TME), rendering most of them resistant to standard-of-care immune checkpoint inhibitors (CPIs). Signal transducer and activator of transcription 3 (STAT3), a ubiquitously expressed transcription factor, has well-defined immunosuppressive functions in several leukocyte populations within the TME. Since the STAT3 protein has been challenging to target using conventional pharmaceutical modalities, we investigated the feasibility of applying systemically delivered RNA interference (RNAi) agents to silence its mRNA directly in tumor-associated immune cells. In preclinical rodent tumor models, chemically stabilized acetylated small-interfering RNAs (siRNAs) selectively silenced Stat3 mRNA in multiple relevant cell types, reduced STAT3 protein levels, and increased cytotoxic T-cell infiltration. In a murine model of CPI-resistant pancreatic cancer, RNAi-mediated Stat3 silencing resulted in tumor growth inhibition, which was further enhanced in combination with CPIs. To further exemplify the utility of RNAi for cancer immunotherapy, this technology was used to silence Cd274, the gene encoding the immune checkpoint protein programmed death-ligand 1 (PD-L1). Interestingly, silencing of Cd274 was effective in tumor models that are resistant to PD-L1 antibody therapy. These data represent the first demonstration of systemic delivery of RNAi agents to the TME and suggest applying this technology for immuno-oncology applications.

Danhongqing formula alleviates cholestatic liver fibrosis by downregulating long non-coding RNA H19 derived from cholangiocytes and inhibiting hepatic stellate cell activation

ObjectiveThis study explores the mechanism of action of Danhongqing formula (DHQ), a compound-based Chinese medicine formula, in the treatment of cholestatic liver fibrosis. MethodsIn vivo experiments were conducted using 8-week-old multidrug resistance protein 2 knockout (Mdr2-/-) mice as an animal model of cholestatic liver fibrosis. DHQ was administered orally for 8 weeks, and its impact on cholestatic liver fibrosis was evaluated by assessing liver function, liver histopathology, and the expression of liver fibrosis-related proteins. Real-time polymerase chain reaction, Western blot, immunohistochemistry and other methods were used to observe the effects of DHQ on long non-coding RNA H19 (H19) and signal transducer and activator of transcription 3 (STAT3) phosphorylation in the liver tissue of Mdr2-/- mice. In addition, cholangiocytes and hepatic stellate cells (HSCs) were cultured in vitro to measure the effects of bile acids on cholangiocyte injury and H19 expression. Cholangiocytes overexpressing H19 were constructed, and a conditioned medium containing H19 was collected to measure its effects on STAT3 protein expression and cell activation. The intervention effect of DHQ on these processes was also investigated. HSCs overexpressing H19 were constructed to measure the impact of H19 on cell activation and assess the intervention effect of DHQ. ResultsDHQ alleviated liver injury, ductular reaction, and fibrosis in Mdr2-/- mice, and inhibited H19 expression, STAT3 expression and STAT3 phosphorylation. This formula also reduced hydrophobic bile acid-induced cholangiocyte injury and the upregulation of H19, inhibited the activation of HSCs induced by cholangiocyte-derived conditioned medium, and decreased the expression of activation markers in HSCs. The overexpression of H19 in a human HSC line confirmed that H19 promoted STAT3 phosphorylation and HSC activation, and DHQ was able to successfully inhibit these effects. ConclusionDHQ effectively alleviated spontaneous cholestatic liver fibrosis in Mdr2-/- mice by inhibiting H19 upregulation in cholangiocytes and preventing the inhibition of STAT3 phosphorylation in HSC, thereby suppressing cell activation.Please cite this article as: Li M, Zhou Y, Zhu H, Xu LM, Ping J. Danhongqing formula alleviates cholestatic liver fibrosis by downregulating long non-coding RNA H19 derived from cholangiocytes and inhibiting hepatic stellate cell activation. J Integr Med. 2024; Epub ahead of print.

Genistein and Sex Hormone Supplementation Modulated Hepatic PPARα, δ, and γ Subtypes and STAT1 Expressions in a NASH Rat Model with Bilateral Orchidectomy.

Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD) that is characterized by hepatic inflammation and steatosis. Currently, limited data exist regarding the risk of NASH in transgender women and the treatment options for this particular population. The use of testosterone supplementation is unfavorable for transgender women, and estrogen supplementation is linked to an increased risk of breast cancer; thus, an isoflavone derivative compound known as "genistein" could serve as a viable substitute for a hormone supplement in this context. The purpose of this study was to investigate the treatment effects and mechanisms of actions of genistein and sex hormones in orchidectomized (ORX) rats with nonalcoholic steatohepatitis induced via a high-fat high-fructose diet (HFHF) model. Male Sprague-Dawley rats (n = 42) were randomly assigned into seven groups; control, ORX + standard diet, HFHF, ORX + HFHF, ORX + HFHF diet + testosterone (50 mg/kg body weight (BW) once weekly), ORX + HFHF diet + estradiol (1.6 mg/kg BW daily), and ORX + HFHF diet + genistein (16 mg/kg BW daily). The duration of the study was 6 weeks. Some parts of liver tissue were used for histological examination by H&E staining. The determination of fat accumulation was performed using Oil Red O staining. SREBP1c and FAS gene expression were quantified using real-time PCR technique. The levels of all types of peroxisome proliferator-activated receptors (PPARs; α, δ, γ), proteins, and signal transducer and activator of transcription 1 (STAT1) signaling pathway were determined by both immunoblotting and immunohistochemistry. Rats in the ORX + HFHF group had the highest degree of hepatic steatosis, lobular inflammation, and hepatocyte ballooning, and showed higher levels of genes related to de novo lipogenesis, including SREBP1c and FAS. The expression of PPARγ and STAT1 were upregulated, while the expression of PPARα and PPARδ were downregulated in the ORX + HFHF group. Testosterone, estradiol and genistein treatments improved NASH histopathology together with the reversal of all types of PPAR protein expressions. Interestingly, genistein decreased the levels of STAT1 protein expression more than those of testosterone and estradiol treatment. Genistein and sex hormone treatment could ameliorate NASH through the upregulation of PPARα, and PPARδ, and the suppression of PPARγ and STAT1 expression.

USP39 Promotes the Viability and Migration of Head and Neck Squamous Cell Carcinoma Cell by Regulating STAT1.

Objective: Ubiquitin-specific peptidase 39 (USP39) plays a carcinogenic role in many cancers, but little research has been conducted examining whether it is involved in head and neck squamous cell carcinoma (HNSCC). Therefore, this study explored the functional role of USP39 in HNSCC. Method: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify differentially expressed proteins (DEPs) between the HNSCC tumor and adjacent healthy tissues. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were used to assess the functional enrichment of DEPs. Immunohistochemistry was used to detect protein expression. The viability and migration of two HNSCC cell lines, namely CAL27 and SCC25, were detected using the cell counting kit-8 assay and a wound healing assay, respectively. Quantitative real-time PCR was used to detect the expression level of signal transducer and activator of transcription 1 (STAT1) mRNA. Results: LC-MS/MS results identified 590 DEPs between HNSCC and adjacent tissues collected from 4 patients. Through GO and KEGG pathway analyses, 34 different proteins were found to be enriched in the spliceosome pathway. The expression levels of USP39 and STAT1 were significantly higher in HNSCC tumor tissue than in adjacent healthy tissue as assessed by LC-MS/MS analysis, and the increased expression of USP39 and STAT1 protein was confirmed by immunohistochemistry in clinical samples collected from 7 additional patients with HNSCC. Knockdown of USP39 or STAT1 inhibited the viability and migration of CAL27 and SCC25 cells. In addition, USP39 knockdown inhibited the expression of STAT1 mRNA in these cells. Conclusion: Our findings indicated that USP39 knockdown may inhibit HNSCC viability and migration by suppressing STAT1 expression. The results of this study suggest that USP39 may be a potential new target for HNSCC clinical therapy or a new biomarker for HNSCC.

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

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. 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. 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. 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.

Nuclear translocation of STAT5 initiates iron overload in huntington's disease by up-regulating IRP1 expression.

Mutant huntingtin (mHtt) proteins interact to form aggregates, disrupting cellular functions including transcriptional dysregulation and iron imbalance in patients with Huntington's disease (HD) and mouse disease models. Previous studies have indicated that mHtt may lead to abnormal iron homeostasis by upregulating the expression of iron response protein 1 (IRP1) in the striatum and cortex of N171-82Q HD transgenic mice, as well as in HEK293 cells expressing the N-terminal fragment of mHtt containing 160 CAG repeats. However, the mechanism underlying the upregulation of IRP1 remains unclear. We investigated the levels and phosphorylation status of signal transducer and activator of transcription 5 (STAT5) in the brains of N171-82Q HD transgenic mice using immunohistochemistry staining. We also assessed the nuclear localization of STAT5 protein through western blot and immunofluorescence, and measured the relative RNA expression levels of STAT5 and IRP1 using RT-PCR in both N171-82Q HD transgenic mice and HEK293 cells expressing the N-terminal fragment of huntingtin. Our findings demonstrate that the transcription factor STAT5 regulates the transcription of the IPR1 gene in HEK293 cells. Notably, both the brains of N171-82Q mice and 160Q HEK293 cells exhibited increased nuclear content of STAT5, despite unchanged total STAT5 expression. These results suggest that mHtt promotes the nuclear translocation of STAT5, leading to enhanced expression of IRP1. The nuclear translocation of STAT5 initiates abnormal iron homeostatic pathways, characterized by elevated IRP1 expression, increased levels of transferrin and transferrin receptor, and iron accumulation in the brains of HD mice. These findings provide valuable insights into potential therapeutic strategies targeting iron homeostasis in HD.

Enterovirus D68 3C protease antagonizes type I interferon signaling by cleaving signal transducer and activator of transcription 1.

Following the successful control of poliovirus, the re-emergence of respiratory enterovirus D68 (EV-D68), a prominent non-polio enterovirus, has become a serious public health concern worldwide. Host innate immune responses are the primary defense against EV-D68 invasion; however, the mechanism underlying viral evasion of the antiviral activity of interferons (IFN) remains unclear. In this study, we found that EV-D68 inhibited type I IFN signaling by cleaving signal transducer and activator of transcription 1 (STAT1), a crucial factor in cellular responses to interferons and other cytokines. We observed that the prototype and circulating EV-D68 strains conserved their ability to induce STAT1 cleavage and attenuate IFN signal transduction. Further investigation revealed that EV-D68 3C protease cleaves STAT1 at the 131Q residue. Interestingly, not all enterovirus-encoded 3C proteases exhibited this ability. EV-D68 and poliovirus 3C proteases efficiently induced STAT1 cleavage; whereas, 3C proteases from EV-A71, coxsackievirus A16, and echoviruses did not. STAT1 cleavage also abolished the nuclear translocation capacity of STAT1 in response to IFN stimulation to activate downstream signaling elements. Overall, these results suggest that STAT1, targeted by viral protease 3C, is utilized by EV-D68 to subvert the host's innate immune response.IMPORTANCEEnterovirus D68 (EV-D68) has significantly transformed over the past decade, evolving from a rare pathogen to a potential pandemic pathogen. The interferon (IFN) signaling pathway is an important defense mechanism and therapeutic target for the host to resist viral invasion. Previous studies have reported that the EV-D68 virus blocks or weakens immune recognition and IFN production in host cells through diverse strategies; however, the mechanisms of EV-D68 resistance to IFN signaling have not been fully elucidated. Our study revealed that EV-D68 relies on its own encoded protease, 3C, to directly cleave signal transducer and activator of transcription 1 (STAT1), a pivotal transduction component in the IFN signaling pathway, disrupting the IFN-mediated antiviral response. Previous studies on human enteroviruses have not documented direct cleavage of the STAT1 protein to evade cellular immune defenses. However, not all enteroviral 3C proteins can cleave STAT1. These findings highlight the diverse evolutionary strategies different human enteroviruses employ to evade host immunity.

Role of STAT3 in pancreatic cancer.

Pancreatic cancer remains a serious and deadly disease, impacting people globally. There remain prominent gaps in the current understanding of the disease, specifically regarding the role of the signal transducer and activator of transcription (STAT) family of proteins in pancreatic tumors. STAT proteins, particularly STAT3, play important roles in pancreatic cancer, especially pancreatic ductal adenocarcinoma (PDAC), which is the most prevalent histotype. The role of STAT3 across a continuum of molecular processes, such as PDAC tumorigenesis and progression, immune escape, drug resistance and stemness, and modulation of the tumor microenvironment (TME), are only a tip of the iceberg. In some ways, the role of STAT3 in PDAC may hold greater importance than that of oncogenic Kirsten rat sarcoma virus (KRAS). This makes STAT3 a highly attractive target for developing targeted therapies for the treatment of pancreatic cancer. In this review, the current knowledge of STAT3 in pancreatic cancer has been summarized, particularly relating to STAT3 activation in cancer cells, cells of the TME, and the state of targeting STAT3 in pre-clinical and clinical trials of PDAC.

Signal Transducer and Activator of Transcription Proteins at the Nexus of Immunodeficiency, Autoimmunity and Cancer.

The signal transducer and activator of transcription (STAT) family of proteins has been demonstrated to perform pivotal roles downstream of a myriad of cytokines, particularly those that control immune cell production and function. This is highlighted by both gain-of-function (GOF) and loss-of-function (LOF) mutations being implicated in various diseases impacting cells of the immune system. These mutations are typically inherited, although somatic GOF mutations are commonly observed in certain immune cell malignancies. This review details the growing appreciation of STAT proteins as a key node linking immunodeficiency, autoimmunity and cancer.

Quercetin, a key active ingredient of Jianpi Zishen Xiehuo Formula, suppresses M1 macrophage polarization and platelet phagocytosis by inhibiting STAT3 activation based on network pharmacology.

Primary immune thrombocytopenia (ITP) is an autoimmune hemorrhagic disease, and abnormal M1 macrophage polarization participates in the pathogenesis of ITP. Jianpi Zishen Xiehuo (JZX) Formula has a good therapeutic effect on ITP. However, its key active ingredients and molecular mechanisms remain unclear. In this study, we explored the key active ingredients and potential targets of JZX in treating ITP using network pharmacology combined with in vitro experimental verification. A total of 157 active ingredients of JZX were identified from public databases, and quercetin was the most important one. One hundred sixty-five intersection targets of active ingredients in JZX, ITP, and macrophage polarization were obtained by Venn diagram. The top three potential targets were signal transducer and activator of transcription 3 (STAT3), protein kinase B (PKB/AKT) 1, and c-JUN through protein-protein interaction analysis. Molecular docking showed that quercetin had strong binding affinities with them all. In vitro experiment, CD16+ monocytes increased in ITP patients compared with healthy controls, which indicated a M1/M2 polarization imbalance in ITP. The expression levels of M1 polarization markers, CD86, CD80, and inducible nitric oxide synthase (iNOS), M1 polarization-associated cytokines, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6), and antibody-opsonized platelet phagocytosis significantly increased in THP-1 macrophages stimulated with lipopolysaccharide (LPS). Quercetin markedly inhibited the expressions of M1 markers, decreased the levels of TNF-α and IL-6, and down-regulated the phosphorylated STAT3 (p-STAT3) protein, which confirmed the prediction by network pharmacology and molecular docking. Importantly, quercetin significantly reduced the phagocytosis of antibody opsonised platelet. In conclusion, quercetin suppressed platelet phagocytosis in M1 macrophages via its anti-inflammatory effects and may serve as a potential drug forthe treatment of ITP. Quercetin could be a key ingredient for JZX against ITP.

Preliminary Safety, Pharmacokinetics, Pharmacodynamics and Clinical Activity of KT-333, a Targeted Protein Degrader of STAT3, in Patients with Relapsed or Refractory Lymphomas, Large Granular Lymphocytic Leukemia, and Solid Tumors

Background: KT-333is a first-in-class, potent, highly selective, heterobifunctional small molecule degrader of the signal transducer and activator of transcription 3 (STAT3) protein. Aberrant activation of STAT3 resulting from activating mutations or deregulated cytokine signaling underlies various malignancies including peripheral T-cell lymphomas (PTCL), cutaneous T-cell lymphoma (CTCL), and large granular lymphocytic leukemia (LGL-L). Approximately 70% of human cancers including hematological malignancies and solid tumors exhibit increased levels of phosphorylated STAT3 (pSTAT3), a biomarker of pathway activation. In non-clinical studies, treatment with KT-333 resulted in durable tumor regressions with weekly (QW) or once every two weeks IV administration in STAT3-dependent T cell lymphomas. STAT3 degradation also sensitized immunocompetent mouse models of solid and liquid cancers to anti-PD1(ASH 2021, SITC 2021). Methods: The ongoing open-label, Phase 1a/1b study is evaluating the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary clinical activity of KT-333 administered as a QW IV infusion on Day 1, 8, 15 and 22 (28-day cycle) in patients (pts) with B- and T-cell lymphomas, Hodgkin's lymphoma and advanced solid tumors (ST) relapsed/refractory (R/R) to at least two prior systemic therapies and LGL-L and T-cell prolymphocytic leukemia R/R to at least one prior therapy. Cycle 1 and 2 blood samples are collected for KT-333 plasma concentrations and to measure changes in STAT3 protein expression in peripheral blood mononuclear cells (PBMCs) using targeted mass spectrometry. Whole blood RNA sequencing measures mRNA levels of STAT3 regulated targets. Plasma levels of inflammatory biomarkers are measured with Luminex. STAT3 degradation and other related biomarker changes in tumor are assessed in patients with accessible tumors. (NCT05225584). Results: As of July 10, 2023, 21 pts were treated at five dose levels (DL) in Phase 1a with a mean number of 5.8 doses. Pts included B-cell non-Hodgkin's lymphoma (n=1: DL5), Hodgkin's lymphoma (HL) (n=1: DL4), CTCL (n=3: DL1, 2 and 4), PTCL (n=1: DL2), LGL-L (n=2: DL5) and ST (n=13: DL1-4) with median age of 61 years (range 30,77) and ECOG performance status of 0 (n=7) or 1 (n=14). No DLTs and no KT-333 related serious adverse events (SAE) were reported. The most common AEs were Grade 1 and 2 and included constipation, fatigue, nausea and anemia. Best response among pts evaluable for response at data cut-off (not including CTCL or HL pts at DL4 or any DL5 pts) included one partial response after two cycles in a CTCL pt at DL2 and SD after two cycles in three ST pts treated at DL3 and DL4. PD data in blood available for DL1-4 demonstrated robust, dose-dependent, and sustained STAT3 degradation in PBMC. The mean maximum degradation of STAT3 by targeted mass spectrometry over the first two weeks in Cycle 1 by DL was (% (range; n)): DL1: 69.9% (52.6% to 84.1%; n=4), DL2: 73.5% (65.5% to 80.7%; n=3), DL3: 79.9% (72.3% to 90.4 %; n=3) and DL4: 86.6% (78.9% to 95.9 %; n=4) with absolute quantification of STAT3 peptides falling below lower limit of quantification of the assay for one pt in DL3 and two in DL4. STAT3 pathway inhibition in blood was demonstrated via transcriptional downregulation of a canonical JAK/STAT3 target, SOCS3, which correlated with changes in STAT3 protein levels. KT-333 also resulted in dose-dependent downregulation of STAT3-regulated inflammatory biomarkers C-reactive protein and serum amyloid A protein in plasma. KT-333 demonstrated linear PK with plasma exposure increasing with dose and reaching levels close to those predicted to be efficacious. Conclusion: The emerging clinical data demonstrate that KT-333 is a potent degrader of STAT3 as demonstrated in PBMCs at doses that are well tolerated. These data provide the first evidence of STAT3 targeted protein degradation in humans with associated STAT3 pathway inhibition, along with potential early signs of antitumor activity, highlighting the potential of heterobifunctional degraders for targeting previously undruggable transcription factors implicated in diseases. Based on non-clinical data and PK/PD modeling, the high levels of degradation achieved so far are expected to be clinically efficacious in STAT3-dependent malignancies. Accrual is ongoing, and analyses from additional patients will be presented at the meeting.

Revisiting the role of endogenous STAT3 in HPV-positive cervical cancer cells.

Novel treatment options for human papillomavirus (HPV)-induced cancers are urgently required. The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) is considered to be constitutively active in HPV-positive cervical cancer cells and essential for their proliferation. Moreover, STAT3 was reported to undergo mutually stimulatory interactions with the HPV E6/E7 oncogenes. Thus, inhibiting STAT3 in HPV-positive cancer cells is under discussion to provide a powerful novel therapeutic strategy. We here show that the antifungal drug ciclopirox destabilizes the STAT3 protein by acting as an iron chelator. However, by exploring the functional consequences of STAT3 inhibition in HPV-positive cancer cells, we obtained several unexpected results. Chemical STAT3 inhibitors heterogeneously affect cervical cancer cell proliferation and those which act antiproliferative also block the growth of STAT3 knockout cells, indicating induction of off-target effects. In contrast to several chemical inhibitors, genetic inhibition of STAT3 expression by either RNA interference or the CRISPR/Cas9 method does not appreciably affect cervical cancer cell proliferation. Transcriptome analyses indicate that blocking STAT3 expression in HPV-positive cancer cells has very limited effects on putative STAT3 target genes. Although the targeted inhibition of specific growth-promoting signaling pathways leads to a feedback activation of STAT3 in cervical cancer cells via Janus kinase1/2, this does not lead to treatment resistance. Moreover, we did not obtain experimental evidence for a STAT3-linked activation of HPV E6/E7 oncogene expression or, vice versa, an E6/E7-dependent activation of STAT3, at endogenous conditions in cervical cancer cells. Collectively, these findings question the essential role of STAT3 in cervical cancer cell proliferation and the strategy to inhibit STAT3 in these cells for therapeutic purposes.

Simultaneous Targeting of IL-1-Signaling and IL-6-Trans-Signaling Preserves Human Pulmonary Endothelial Barrier Function During a Cytokine Storm.

Systemic inflammatory diseases, such as sepsis and severe COVID-19, provoke acute respiratory distress syndrome in which the pathological hyperpermeability of the microvasculature, induced by uncontrolled inflammatory stimulation, causes pulmonary edema. Identifying the inflammatory mediators that induce human lung microvascular endothelial cell barrier dysfunction is essential to find the best anti-inflammatory treatments for critically ill acute respiratory distress syndrome patients. We have compared the responses of primary human lung microvascular endothelial cells to the main inflammatory mediators involved in cytokine storms induced by sepsis and SARS-CoV2 pulmonary infection and to sera from healthy donors and severely ill patients with sepsis. Endothelial barrier function was measured by electric cell-substrate impedance sensing, quantitative confocal microscopy, and Western blot. The human lung microvascular endothelial cell barrier was completely disrupted by IL (interleukin)-6 conjugated with soluble IL-6R (IL-6 receptor) and by IL-1β, moderately affected by TNF (tumor necrosis factor)-α and IFN (interferon)-γ and unaffected by other cytokines and chemokines, such as IL-6, IL-8, MCP (monocyte chemoattractant protein)-1 and MCP-3. The inhibition of IL-1 and IL-6R simultaneously, but not separately, significantly reduced endothelial hyperpermeability on exposing human lung microvascular endothelial cells to a cytokine storm consisting of 8 inflammatory mediators or to sera from patients with sepsis. Simultaneous inhibition of IL-1 and JAK (Janus kinase)-STAT (signal transducer and activator of transcription protein), a signaling node downstream IL-6 and IFN-γ, also prevented septic serum-induced endothelial barrier disruption. These findings strongly suggest a major role for both IL-6 trans-signaling and IL-1β signaling in the pathological increase in permeability of the human lung microvasculature and reveal combinatorial strategies that enable the gradual control of pulmonary endothelial barrier function in response to a cytokine storm.

Upregulated SPAG6 correlates with increased STAT1 and is associated with reduced sensitivity of interferon-α response in BCR::ABL1 negative myeloproliferative neoplasms.

Sperm-associated antigen 6 (SPAG6) has been identified as an oncogene or tumor suppressor in various types of human cancer. However, the role of SPAG6 in BCR::ABL1 negative myeloproliferative neoplasms (MPNs) remains unclear. Herein, we found that SPAG6 was upregulated at the mRNA level in primary MPN cells and MPN-derived leukemia cell lines. The SPAG6 protein was primarily located in the cytoplasm around the nucleus and positively correlated with β-tubulin expression. In vitro, forced expression of SPAG6 increased cell clone formation and promoted G1 to S cell cycle progression. Downregulation of SPAG6 promoted apoptosis, reduced G1 to S phase transition, and impaired cell proliferation and cytokine release accompanied by downregulated signal transducer and activator of transcription 1 (STAT1) expression. Furthermore, the inhibitory effect of interferon-α (INF-α) on the primary MPN cells with high SPAG6 expression was decreased. Downregulation of SPAG6 enhanced STAT1 induction, thus enhancing the proapoptotic and cell cycle arrest effects of INF-α both in vitro and in vivo. Finally, a decrease in SPAG6 protein expression was noted when the STAT1 signaling was blocked. Chromatin immunoprecipitation assays indicated that STAT1 protein could bind to the SPAG6 promoter, while the dual-luciferase reporter assay indicated that STAT1 could promote the expression of SPAG6. Our results substantiate the relationship between upregulated SPAG6, increased STAT1, and reduced sensitivity to INF-α response in MPN.