STAT3 Inhibition Research Articles

STAT3 Inhibitor Increases α-Synuclein in PFF-Treated Astroglia Cells by Dysregulating Autophagy and Potentially Affects Exosome Biogenesis.

Astrocytes are the most abundant cells in the brain and show neuroprotective function in CNS and reactive astrocytes are characteristic in neurodegenerative diseases. The JAK2-STAT3 pathway plays a crucial role in the process of astrocyte activation. However, as a hallmark of Parkinson's disease, the change in α-syn under the influence of STAT3 inhibitor and the underlying cellular mechanisms remain elusive. Here, we show that PFF can induce an increase in α-syn in SVG p12 cells, which is further enhanced after the inhibition of STAT3. The underlying mechanisms involve the downregulation of autophagy levels and a concurrent decrease in lysosomal function after inhibition of STAT3. Additionally, we observed inhibition of STAT3 resulted in reduced exosome secretion in SVG p12 cells. This is attributed to alterations in SNARE, leading to impaired fusion between MVBs and the cell membrane, subsequently causing the accumulation of intracellular MVBs. Taken together, our data demonstrates that inhibition of STAT3 decreases both the autophagy and lysosome function, which may increase MVBs production. However, we found a potentially decreased exosome production that may be implicated with SNARE complex and need further exploration.

Interleukin-10 inhibits important components of trained immunity in human monocytes.

Trained immunity induces antigen-agnostic enhancement of host defense and protection against secondary infections, but inappropriate activation can contribute to the pathophysiology of inflammatory diseases. Tight regulation of trained immunity is therefore needed to avoid pathology, but little is known about the endogenous processes that modulate it. Here, we investigated the potential of IL-10, a prototypical anti-inflammatory cytokine, to inhibit trained immunity. IL-10 induced tolerance and inhibited trained immunity in primary human monocytes at both functional and transcriptional levels. Inhibition of STAT3, a signaling route that mediates IL-10 signals, induced trained immunity. IL-10 downregulated glycolytic and oxidative metabolism in monocytes, but did not impact the metabolic effects of β-glucan-induced trained immunity. Furthermore, IL-10 prevented increased ROS production in BCG-induced training, but did not influence phagocytosis upregulation. In a cohort study of healthy volunteers vaccinated with BCG, genetic variants that influenced IL-10 or its receptor modulated BCG-induced trained immunity. Furthermore, circulating IL-10 concentrations were negatively correlated with induction of trained immunity after BCG vaccination in a sex-specific manner. In conclusion, IL-10 inhibited several, albeit not all, immunological functions amplified after induction of trained immunity. Follow-up studies should explore the precise molecular mechanism that mediate the effects of IL-10 on trained immunity. Addressing these knowledge gaps is an important step towards optimizing IL-10's potential as a therapeutic target in diseases characterized by inappropriate induction of trained immunity.

Effect of Soy Isoflavone on Prostate Cancer Cell Apoptosis Through Inhibition of STAT3, ERK, and AKT

Genistein, an isoflavone found in soybeans, exhibits antioxidant, anti-inflammatory, and anticancer properties. This study explored the molecular mechanisms behind genistein’s anticancer effects in prostate cancer DU145 cells. In this study, genistein decreased cell viability, increased annexin V-PE(+) cells, and enhanced the sub-G0/G1 peak by flow cytometric analysis. Increased reactive oxygen species increased mitochondrial depolarization indicating mitochondrial dysfunction and inhibition of ATP formation were also observed in genistein-treated DU145 cells. Genistein upregulated p53 at the mRNA and protein levels and increased caspase-3/7 activity along with the cleavage of Bax, procaspase-3, and PARP. With the increasing genistein concentrations, the percentage of cells in the sub-G0/G1 peak and G2/M phase increased, which was inhibited by treatment with the pan-caspase inhibitor Z-VAD together with 100 μM genistein, which had little toxicity to normal prostate epithelial HPrEC cells. Genistein treatment simultaneously inhibited the activation of STAT3 and other closely related oncogenic kinases such as AKT and ERK and p38 and decreased VEGF expression. Taken together, these results suggest that genistein inhibits the growth of DU145 cells and induces apoptosis by inhibiting STAT3, AKT, ERK, and p38 which provides a molecular basis for the anticancer activity of genistein and suggests its potential as a valuable therapeutic candidate for prostate cancer.

Macrophage-mediated interleukin-6 signaling drives ryanodine receptor-2 calcium leak in postoperative atrial fibrillation

Abstract Background Postoperative atrial fibrillation (poAF) is self-limited AF that occurs within days after cardiac surgery in one-third of patients. Clinical and preclinical studies have demonstrated that the magnitude of the perioperative increase in systemic inflammation, in particular mediated by interleukin (IL)-6, correlates with poAF risk. However, no studies to-date have mechanistically linked IL-6 signaling to fundamental arrhythmia mechanisms or identified the specific cell types driving postoperative atrial IL-6 signaling. Methods We performed single-cell RNA sequencing (scRNAseq), followed by pseudotime trajectory and cell-cell communication analyses on atrial non-myocytes comparing mice with and without poAF. We followed up our scRNAseq findings with pharmacologic and genetic approaches in mice to validate pathways related to macrophage-mediated IL-6 signaling. We used confocal imaging to assess calcium-signaling mechanisms at the single atrial cardiomyocyte (ACM) level and performed parallel patch-clamp studies in isolated human ACMs as well as biochemical analyses of human atrial tissue to assess the translational relevance of our findings. Results Our scRNAseq results demonstrated macrophages to be the most prominently altered cell type in the atria of mice with poAF. Pseudotime trajectory analyses revealed IL-6 to be one of the top inflammatory pathways implicated in macrophage transcriptional state. Indeed, both macrophage depletion and conditional knockout of IL-6 receptors in macrophages were sufficient to prevent poAF. We found that inhibition of STAT3, which is downstream of the IL-6Ra, with FDA-approved phospho-STAT3 inhibitor TTI-101 prevented poAF in mice. Lastly, we demonstrate that enhanced STAT3 activity in poAF promotes arrhythmogenic Ca2+ sparks and waves through ryanodine receptor-2 dysfunction, and that CaMKII inhibition is sufficient to ameliorate Ca2+ mishandling at the single atrial myocyte level. Conclusions Taken together, we use an integrated approach incorporating mouse and human biochemical, functional, and single-cell sequencing data to demonstrate that infiltrating atrial macrophages are fundamentally required for poAF. IL-6 was found to be a critical pathway upregulated in poAF leading to downstream ryanodine receptor-2 dysfunction and atrial arrhythmogenesis. Our findings portend significant therapeutic utility by providing robust mechanistic evidence that targeting the IL-6 axis may be used for poAF prevention and treatment in a clinically amenable timeframe.

Colorectal Cancer Cell-Derived Extracellular Vesicles Promote Angiogenesis Through JAK/STAT3/VEGFA Signaling

Background: Angiogenesis plays a crucial role in the growth of colorectal cancer (CRC). Recent studies have identified extracellular vesicles (EVs) in the tumor microenvironment as important mediators of cell-to-cell communication. However, the specific role and mechanisms of CRC-derived EVs in regulating tumor angiogenesis remain to be further investigated. Methods: EVs were isolated from the conditioned medium of the CRC cells using ultracentrifugation. We investigated the effects of HT-29-derived EVs on tumor growth and angiogenesis in a subcutaneous HT-29 CRC tumor model in mice. Additionally, we evaluated the impact of HT-29-derived EVs on the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs). Subsequently, bioinformatics analysis was performed to identify relevant signaling pathways, and pathway inhibitors were used to block the activation of these pathways, aiming to elucidate their roles in angiogenesis. Results: We found that HT-29-derived EVs can promote tumor growth and angiogenesis in vivo, as well as significantly enhance the proliferation, migration, and tube formation of HUVECs. Bioinformatics analysis revealed that HT-29-derived EVs may regulate angiogenesis through the JAK/STAT3 signaling pathway. Specifically, we observed that CRC-derived EVs promoted the phosphorylation of STAT3 (p-STAT3) and the expression of VEGFA in the nucleus of HUVECs. Treatment with the STAT3 inhibitor Stattic reduced the nuclear expression of p-STAT3, which impaired its function as a transcription factor, thereby inhibiting VEGFA expression and the pro-angiogenic effects of CRC-derived EVs. Conclusions: EVs derived from CRC cells promote CRC tumor angiogenesis by regulating VEGFA through the JAK/STAT3 pathway in endothelial cells.

Association between premature vascular smooth muscle cells senescence and vascular inflammation in Takayasu’s arteritis

ObjectivesArterial wall inflammation and remodelling are the characteristic features of Takayasu’s arteritis (TAK). It has been proposed that vascular smooth muscle cells (VSMCs) are the main targeted cells of inflammatory...

Bidirectional Impact of Varying Severity of Acute Kidney Injury on Calcium Oxalate Stone Formation.

Acute Kidney Injury (AKI) is a prevalent renal disorder. The occurrence of AKI may promote the formation of renal calcium oxalate stones by exerting continuous effects on renal tubular epithelial cells. We aimed to delineate the molecular interplay between AKI and nephrolithiasis. A mild (20 min) and severe (30 min) renal ischemia-reperfusion injury model was established in mice. Seven days after injury, calcium oxalate stones were induced using glyoxylate (Gly) to evaluate the impact of AKI on the formation of kidney stones. Transcriptome sequencing was performed on tubular epithelial cells (TECs) to elucidate the relationship between AKI severity and kidney stones. Key transcription factors (TF) regulating differential gene transcription levels were identified using motif analysis, and pioglitazone, ginkgetin, and fludarabine were used for targeted therapy to validate key transcription factors as potential targets for kidney stone treatment. Severe AKI led to increased deposition of calcium oxalate crystals in renal, impaired kidney function, and upregulation of kidney stone-related gene expression. In contrast, mild AKI was associated with decreased crystal deposition, preserved kidney function, and downregulation of similar gene expression. Transcriptomic analysis revealed that genes associated with inflammation and cell adhesion pathways were significantly upregulated after severe AKI, while genes related to energy metabolism pathways were significantly upregulated after mild AKI. An integrative bioinformatic analysis uncovered a TF regulatory network within TECs, pinpointing that PKNOX1 was involved in the upregulation of inflammation-related genes after severe AKI, and inhibiting PKNOX1 function with Pioglitazone could simultaneously reduce the increase of calcium oxalate crystals after severe AKI in kidney. On the other hand, motif analysis also revealed the protective role of STAT1 in the kidneys after mild AKI, enhancing the function of STAT1 with Ginkgetin could reduce kidney stone formation, while the specific inhibitor of STAT1, Fludarabine, could eliminate the therapeutic effects of mild AKI on kidney stones. Inadequate repair of tubular epithelial cells after severe AKI increases the risk of kidney stone formation, with the upregulation of inflammation-related genes regulated by PKNOX1 playing a role in this process. Inhibiting PKNOX1 function can reduce kidney stone formation. Conversely, after mild AKI, effective cell repair through upregulation of STAT1 expression can protect TEC function, reduce stone formation, and activating STAT1 function can also achieve the goal of treating kidney stones.

Interleukin-22 improves ovulation in polycystic ovary syndrome via STAT3 signaling.

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disease, which leads to serious impairment of reproductive health in women of child-bearing age. Anovulation or oligo-ovulation is a common clinical manifestation of PCOS patients. A disturbance of the ovarian immune microenvironment contributes to the disorders of follicle development and ovulation; however, the underlying mechanism remains unclear. Here we demonstrated the protective effect of immune factor interleukin-22 (IL-22) on PCOS follicle development and ovulation. Follicular IL-22 levels were significantly lower in PCOS patients than in the control group and were positively correlated with oocyte fertilization rate and high-quality embryo rate. Additionally, IL-22 evidently improved follicle development in vitro and promoted ovulation-related gene expression, which was disrupted by the depletion of interleukin-22 receptor 1 (IL-22R1) or inhibition of STAT3 in granulosa cells. This indicates that IL-22 acts through IL-22R1 and the STAT3 signaling pathway to promote follicle development and ovulation in PCOS. In summary, this study has elucidated the vital role of the ovarian immune microenvironment in follicle development and ovulation. Application of IL-22 may provide new insights into the treatment of PCOS patients.

Maintenance of hematopoietic stem cells by non-tyrosine-phosphorylated STAT5 and JAK inhibition

AbstractAdult hematopoietic stem cells (HSCs) are responsible for the lifelong production of blood and immune cells, a process regulated by extracellular cues, including cytokines. Many cytokines signal through the conserved Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway in which tyrosine-phosphorylated STATs (pSTATs) function as transcription factors. STAT5 is a pivotal downstream mediator of several cytokines known to regulate hematopoiesis, but its function in the HSC compartment remains poorly understood. In this study, we show that STAT5-deficient HSCs exhibit an unusual phenotype, including reduced multilineage repopulation and self-renewal, combined with reduced exit from quiescence and increased differentiation. This was driven not only by the loss of canonical pSTAT5 signaling, but also by the loss of distinct transcriptional functions mediated by STAT5 that lack canonical tyrosine phosphorylation (uSTAT5). Consistent with this concept, expression of an unphosphorylatable STAT5 mutant constrained wild-type HSC differentiation, promoted their maintenance, and upregulated transcriptional programs associated with quiescence and stemness. The JAK1/2 inhibitor, ruxolitinib, which increased the uSTAT5:pSTAT5 ratio, had similar effects on murine HSC function; it constrained HSC differentiation and proliferation, promoted HSC maintenance, and upregulated transcriptional programs associated with stemness. Ruxolitinib also enhanced serial replating of normal human hematopoietic stem and progenitor cells (HSPCs), CALR-mutant murine HSCs, and HSPCs obtained from patients with myelofibrosis. Our results therefore reveal a previously unrecognized interplay between pSTAT5 and uSTAT5 in the control of HSC function and highlight JAK inhibition as a potential strategy for enhancing HSC function during ex vivo culture. Increased levels of uSTAT5 may also contribute to the failure of JAK inhibitors to eradicate myeloproliferative neoplasms.

KLHL21 suppresses gastric tumourigenesis via maintaining STAT3 signalling equilibrium in stomach homoeostasis

ObjectivePrecancerous metaplasia transition to dysplasia poses a risk for subsequent intestinal-type gastric adenocarcinoma. However, the molecular basis underlying the transformation from metaplastic to cancerous cells remains poorly understood.DesignAn integrated analysis...

The LINC00319 binding to STAT3 promotes the cell proliferation, migration, invasion and EMT process in oral squamous cell carcinoma

BackgroundLong non-coding RNA LINC00319 has been implicated in the progression of various cancers, including oral squamous cell carcinoma (OSCC). While our previous work has revealed some aspects of LINC00319's role in OSCC, including its upregulation and involvement in a competing endogenous RNA (ceRNA) mechanism, the full extent of its functions and regulatory mechanisms in OSCC progression remain to be fully elucidated. ObjectiveThis study aimed to investigate the function of LINC00319 in OSCC and its potential interaction with the STAT3 signaling pathway, thus uncovering novel regulatory mechanisms and therapeutic targets. MethodsBioinformatics analysis was performed using TCGA data to evaluate LINC00319 expression in OSCC tissues and its correlation with STAT3 signaling. The direct binding between LINC00319 and STAT3 was examined by RNA pull-down, FISH, and RIP assays. Functional experiments, including CCK-8, transwell migration and invasion assays, and western blot analysis of EMT markers and STAT3 pathway activation, were conducted to assess the effects of LINC00319 on OSCC cell behaviors and its interaction with the STAT3 signaling pathway. In vivo xenograft models were established to validate the role of LINC00319 in tumor growth and STAT3 activation. ResultsLINC00319 expression was significantly upregulated in OSCC tissues compared to normal tissues, and high LINC00319 expression correlated with STAT3 signaling activation. Mechanistically, LINC00319 directly bound to STAT3 protein and promoted its phosphorylation at Tyr705. LINC00319 overexpression enhanced, while its knockdown suppressed, the proliferation, migration, invasion, and EMT of OSCC cells. These oncogenic effects were mediated through STAT3 activation and could be reversed by the STAT3 inhibitor stattic. In vivo experiments further confirmed that LINC00319 silencing inhibited tumor growth and STAT3 phosphorylation. ConclusionThis study uncovers that LINC00319 promotes OSCC tumorigenesis by directly binding to and activating STAT3 signaling. These findings provide new insights into the regulatory mechanisms of STAT3 by long non-coding RNAs and highlight the potential of LINC00319 as a biomarker and therapeutic target in OSCC.

Interlinking Human-Derived Leukemia Cells with Clinicopathological Therapeutics: Exploring Capsaicin's Anti-Cancer Mechanisms/potential for Leukemia Patients

Capsaicin, a bioactive compound isolated from chilli peppers, comes out as a potential agent for its anti-proliferation role in leukemia patients’ therapy. Objectives: This systematic review describes the Clinicopathological therapeutic potential of capsaicin against leukemia emphasizing the mechanism by which it inhibits growth through apoptosis, the cell cycle, and regulation of oncogenic signalling pathways in human-derived leukemia cell lines. Methods: According to PRISMA guidelines, the 75 studies were obtained from the various databases January 2013 and April 2024; Semantic Scholar, Google Scholar, PubMed as well as Frontiers and Link Springer. 50% (38) of the articles were taken from Semantic Scholar, 30% (22) from Google Scholar and 20% (15) from other search engines including PubMed and Link Springer. The papers included the inclusion criteria of PRISMA based on demographics, key outcomes and Anti-Cancer mechanisms majorly. Results: Capsaicin research published in America, Europe, Asia and Africa proves that it regulates vital processes at the cellular level including production of ROS, inhibition of NF-κB, STAT3, MAPK and cellular apoptosis. As human-derived cell lines are playing a pivotal role in cancer therapy, silicon methodologies along with in-vitro and in-vivo verification also shed more light on the improvement by capsaicin of the effectiveness of standard chemotherapeutic agents in combination with preferential killing of leukemic cells. Conclusions: Significantly, there were low levels of cytotoxicity of capsaicin to normal peripheral blood hematopoietic cells indicating that the compound is safe to use inhibiting the key oncogenic pathways and enhancing the efficacy of existing chemotherapeutic agents makes it a promising candidate for future therapeutic development.

JAK/STAT Signaling Pathway Mediates Anti-Tumor Immunity of CD8+ T Cells in Renal Cancer.

CD8+ T cells play a crucial role in immune responses, and have significant potential in tumor immunotherapy. The JAK/STAT pathway is essential for cytokine signal transduction and is linked to immune escape. However, its role in mediating CD8+ T cell anti-tumor immunity in renal cancer is not fully understood. To study the mechanisms underlying CD8+ T cell-mediated anti-tumor immunity and propose new possibilities for immunotherapy in patients with renal cancer. CD8+ T cells from mouse spleens were sorted using immunomagnetic beads, and their purity was confirmed by flow cytometry. Proliferation was analyzed using CCK-8 and CFSE assays. Activation of CD8+ T cells was assessed through ELISA and Western blotting. The malignant properties of Renca cells were evaluated through flow cytometry, Calcein-AM/PI staining, wound healing, Transwell, Western blot, and immunofluorescence. A subcutaneous tumor model in nude mice was used to examine the role of JAK1/STAT1 pathway in vivo. Inhibitors of JAK1 and STAT1 significantly reduced the proliferation and activation of CD8+ T cell. Co-culture with CD8+ T cells increased apoptosis and inhibited the proliferation, migration, and invasion of Renca cells. The effects were diminished by JAK1 and STAT1 inhibitors, confirming that CD8+ T cells exert antitumor effects through the JAK1/STAT1 pathway. In vivo, inhibition of this pathway reduced the anti-tumor effects of CD8+ T cells. Inhibitors of JAK1 and STAT1 weakened the antitumor effects of CD8+ T cells, suggesting that targeting this pathway could enhance CD8+ T cell-mediated immunity in renal cancer.

IL-22 resolves MASLD via enterocyte STAT3 restoration of diet-perturbed intestinal homeostasis

The exponential rise in metabolic dysfunction-associated steatotic liver disease (MASLD) parallels the ever-increasing consumption of energy-dense diets, underscoring the need for effective MASLD-resolving drugs. MASLD pathogenesis is linked to obesity, diabetes, "gut-liver axis" alterations, and defective interleukin-22 (IL-22) signaling. Although barrier-protective IL-22 blunts diet-induced metabolic alterations, inhibits lipid intake, and reverses microbial dysbiosis, obesogenic diets rapidly suppress its production by small intestine-localized innate lymphocytes. This results in STAT3 inhibition in intestinal epithelial cells (IECs) and expansion of the absorptive enterocyte compartment. These MASLD-sustaining aberrations were reversed by administration of recombinant IL-22, which resolved hepatosteatosis, inflammation, fibrosis, and insulin resistance. Exogenous IL-22 exerted its therapeutic effects through its IEC receptor, rather than hepatocytes, activating STAT3 and inhibiting WNT-β-catenin signaling to shrink the absorptive enterocyte compartment. By reversing diet-reinforced macronutrient absorption, the main source of liver lipids, IL-22 signaling restoration represents a potentially effective interception of dietary obesity and MASLD.

The iNKT cell ligand α-GalCer prevents murine septic shock by inducing IL10-producing iNKT and B cells.

α-galactosylceramide (α-GalCer), a prototypical agonist of invariant natural killer T (iNKT) cells, stimulates iNKT cells to produce various cytokines such as IFNγ and IL4. Moreover, repeated α-GalCer treatment can cause protective or pathogenic outcomes in various immune-mediated diseases. However, the precise role of α-GalCer-activated iNKT cells in sepsis development remains unclear. To address this issue, we employed a lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced murine sepsis model and two alternative models. Sepsis was induced in wild-type (WT) C57BL/6 (B6) mice by three methods (LPS/D-GalN, α-GalCer/D-GalN, and cecal slurry), and these mice were monitored for survival rates. WT B6 mice were intraperitoneally injected with α-GalCer or OCH (an IL4-biased α-GalCer analog) one week prior to the induction of sepsis. To investigate the effects of α-GalCer-mediated iNKT cell activation on sepsis development, immune responses were analyzed by flow cytometry using splenocytes and liver-infiltrating leukocytes. In addition, a STAT6 inhibitor (AS1517499) and an IL10 inhibitor (AS101) were employed to evaluate the involvement of IL4 or IL10 signaling. Furthermore, we performed B cell adoptive transfers to examine the contribution of α-GalCer-induced regulatory B (Breg) cell populations in sepsis protection. In vivo α-GalCer pretreatment polarized iNKT cells towards IL4- and IL10-producing phenotypes, significantly attenuating LPS/D-GalN-induced septic lethality in WT B6 mice. Furthermore, α-GalCer pretreatment reduced the infiltration of immune cells to the liver and attenuated pro-inflammatory cytokine production. Treatment with a STAT6 inhibitor was unable to modulate disease progression, indicating that IL4 signaling did not significantly affect iNKT cell-mediated protection against sepsis. This finding was confirmed by pretreatment with OCH, which did not alter sepsis outcomes. However, interestingly, prophylactic effects of α-GalCer on sepsis were significantly suppressed by treatment with an IL10 antagonist, suggesting induction of IL10-dependent anti-inflammatory responses. In addition to IL10-producing iNKT cells, IL10-producing B cell populations were significantly increased after α-GalCer pretreatment. Overall, our results identify α-GalCer-mediated induction of IL10 by iNKT and B cells as a promising option for controlling the pathogenesis of postoperative sepsis.

Deficiency in epithelium RAD50 aggravates UC via IL-6-mediated JAK1/2-STAT3 signaling and promotes development of colitis-associated cancer in mice.

Ulcerative colitis (UC) is one of the most important risk factors for developing colitis-associated cancer (CAC). Persistent DNA damage increases CAC risk and has been observed in patients with UC. We aimed to identify the regulatory role of RAD50, a DNA double-strand breaks (DSBs) sensor, in UC progression to CAC. DSBs and RAD50 expression in IBD and CAC cell and mouse models were assessed. Mice with intestinal epithelial RAD50 deletion (RAD50IEC-KO) were used to examine the role of RAD50 in colitis and CAC. Along with the increased γ-H2AX expression in colitis and CAC models, RAD50 expression reduced in human IBD and CAC as well as in mouse models. Furthermore, RAD50IEC-KO sensitizes mice to dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis. RNA-seq analyses revealed that RAD50 activated the cytokine-cytokine receptor response, which was amplified through the JAK-STAT pathway. RAD50 directly interacts with STAT3 and subsequently inhibits its phosphorylation, which may disrupt the IL-6-JAK1/2-STAT3-IL-6 feed-forward loop. Pharmacological STAT3 inhibition relieves colitis in RAD50IEC-KO mice. Severe DSBs, increased cell proliferation, and extended inflammatory response were identified in RAD50-deficienct cells, which promoted azoxymethane (AOM)-DSS-induced colon tumor development in RAD50IEC-KO mice. RAD50 exerts anti-IL-6-related inflammatory effects in colitis and suppresses CAC. Increasing RAD50 level in colon tissues may be promising for treating patients with UC and CAC.

ETHE1 dampens colorectal cancer angiogenesis by promoting TC45 Dephosphorylation of STAT3 to inhibit VEGF-A expression

Angiogenesis is critical for colorectal cancer (CRC) progression, but its mechanisms remain unclear. Here, we reveal that ethylmalonic encephalopathy protein 1 (ETHE1), an essential enzyme in hydrogen sulfide catabolism, inhibits VEGF-A expression and tumor angiogenesis in vitro and in vivo. Moreover, we find that this biological function of ETHE1 depends on the STAT3/VEGF-A pathway. Further investigation demonstrates that ETHE1 promotes the interaction between T cell protein tyrosine phosphatase (TC45) and STAT3, resulting in decreased STAT3 phosphorylation and inhibition of the STAT3 signaling pathway. In clinical samples, we find that ETHE1 is downregulated in CRC and positively correlates with survival outcomes of CRC patients. Meanwhile, the negative correlation of ETHE1 and VEGF-A expression is verified in CRC specimens, and the patients with low ETHE1 and high VEGF-A expression exhibits poorer prognosis. Collectively, our study identifies ETHE1 as a novel regulator of tumor angiogenesis, implying its potential as a prognostic biomarker and promising antiangiogenic target for CRC patients.

The involvement of the Stat1/Nrf2 pathway in exacerbating Crizotinib-induced liver injury: implications for ferroptosis

Crizotinib carries an FDA hepatotoxicity warning, yet analysis of the FAERS database suggests that the severity of its hepatotoxicity risks, including progression to hepatitis and liver failure, might be underreported. However, the underlying mechanism remains poorly understood, and effective intervention strategies are lacking. Here, mRNA-sequencing analysis, along with KEGG and GO analyses, revealed that DEGs linked to Crizotinib-induced hepatotoxicity predominantly associate with the ferroptosis pathway which was identified as the principal mechanism behind Crizotinib-induced hepatocyte death. Furthermore, we found that ferroptosis inhibitors, namely Ferrostatin-1 and Deferoxamine mesylate, significantly reduced Crizotinib-induced hepatotoxicity and ferroptosis in both in vivo and in vitro settings. We have also discovered that overexpression of AAV8-mediated Nrf2 could mitigate Crizotinib-induced hepatotoxicity and ferroptosis in vivo by restoring the imbalance in glutathione metabolism, iron homeostasis, and lipid peroxidation. Additionally, both Stat1 deficiency and the Stat1 inhibitor NSC118218 were found to reduce Crizotinib-induced ferroptosis. Mechanistically, Crizotinib induces the phosphorylation of Stat1 at Ser727 but not Tyr701, promoting the transcriptional inhibition of Nrf2 expression after its entry into the nucleus to promote ferroptosis. Meanwhile, we found that MgIG and GA protected against hepatotoxicity to counteract ferroptosis without affecting or compromising the anti-cancer activity of Crizotinib, with a mechanism potentially related to the Stat1/Nrf2 pathway. Overall, our findings identify that the phosphorylation activation of Stat1 Ser727, rather than Tyr701, promotes ferroptosis through transcriptional inhibition of Nrf2, and highlight MgIG and GA as potential therapeutic approaches to enhance the safety of Crizotinib-based cancer therapy.

Unraveling Stereochemical Structure-Activity Relationships of Sesquiterpene Lactones for Inhibitory Effects on STAT3 Activation.

Sesquiterpene lactones, a class of natural compounds abundant in the Asteraceae family, have gained attention owing to their diverse biological activities, and particularly their anti-proliferative effects on human cancer cells. In this study, we systematically investigated the structure-activity relationship of ten sesquiterpene lactones with the aim of elucidating the structural determinants for the STAT3 inhibition governing their anti-proliferative effects. Our findings revealed a significant correlation between the STAT3 inhibitory activity and the anti-proliferative effects of sesquiterpene lactones in MDA-MB-231 breast cancer cell lines. Among the compounds tested, alantolactone and isoalantolactone emerged as the most potent STAT3 inhibitors, highlighting their potential as candidates for anticancer drug development. Through protein-ligand docking studies, we revealed the structural basis of STAT3 inhibition by sesquiterpene lactones, emphasizing the critical role of hydrogen-bonding interactions with key residues, including Arg609, Ser611, Glu612, and Ser613, in the SH2 domain of STAT3. Furthermore, our conformational analysis revealed the decisive role of the torsion angle within the geometry-optimized structures of sesquiterpene lactones in their STAT3 inhibitory activity (R=0.80, p<0.01). These findings not only provide preclinical evidence for sesquiterpene lactones as promising phytomedicines against diseases associated with abnormal STAT3 activation, but also highlight the importance of stereochemical aspects in their activity.

Abstract Tu085: The β IV -spectrin/STAT3 Complex regulates the orientation of cardiac hypertrophic growth

Background: Cardiac hypertrophy is a major risk factor for adverse cardiovascular events including heart failure and arrhythmia. However, the precise orientation of cell and organ growth varies considerably depending on stress type and duration with important implications for cardiac function. Despite this, little is known regarding the mechanisms that regulate hypertrophic orientation. Here we evaluate the role of the cytoskeletal protein β IV -spectrin and signal transducer and activator of transcription (STAT3) in directing the orientation of pressure overload-induced hypertrophy. Methods: Transgenic mouse models with altered STAT3 signaling through modified interaction with its scaffolding partner β IV -spectrin, or phospho-regulation of STAT3 directly, were evaluated at baseline and transaortic constriction (TAC) for its role in promoting concentric versus eccentric morphologies and resulting impact on systolic function. Unbiased screening of gene expression from these structurally divergent states were evaluated for pathways responsible for directing myocyte length/width. These pathways were tested in vitro using primary mouse myocytes and in vivo to tune growth patterns for therapeutic intervention. Results: Loss of β IV -spectrin or direct STAT3 activation promoted a preferential increase in myocyte length over width, resulting in dilation of the left ventricular (LV) chamber (eccentric hypertrophy) and decreased systolic function. Conversely, preservation of β IV -spectrin favored an increase in myocyte width without LV dilation (concentric hypertrophy) and preserved systolic function in response to TAC. Differential expression of genes associated with microtubule dynamics were identified in concentric vs. eccentric hypertrophic states. In vitro assays revealed a relationship between β IV -spectrin/STAT3 signaling and microtubule stability which impacted spatial distribution of mRNA for the sarcomeric gene actc1 . Finally, intervention with pharmacologic STAT3 inhibition following chronic 6-week TAC successfully recovered concentric growth with improved systolic function. Conclusions: These data identify a novel and pivotal role for β IV -spectrin/STAT3 to modify microtubule dynamics and sarcomeric transcript distribution to direct myocyte geometry and therapeutically serve in the prevention or recovery from HF. These mechanisms further illustrate the unique separation of hypertrophic drivers from growth orientation as distinct pathways in cardiac remodeling.