STAT3 Activation Research Articles

A New Renieramycin T Right-Half Analog as a Small Molecule Degrader of STAT3.

Constitutive activation of STAT3 contributes to tumor development and metastasis, making it a promising target for cancer therapy. (1R,4R,5S)-10-hydroxy-9-methoxy-8,11-dimethyl-3-(naphthalen-2-ylmethyl)-1,2,3,4,5,6-hexahydro-1,5-epiminobenzo[d]azocine-4-carbonitrile, DH_31, a new derivative of the marine natural product Renieramycin T, showed potent activity against H292 and H460 cells, with IC50 values of 5.54 ± 1.04 µM and 2.9 ± 0.58 µM, respectively. Structure-activity relationship (SAR) analysis suggests that adding a naphthalene ring with methyl linkers to ring C and a hydroxyl group to ring E enhances the cytotoxic effect of DH_31. At 1-2.5 µM, DH_31 significantly inhibited EMT phenotypes such as migration, and sensitized cells to anoikis. Consistent with the upregulation of ZO1 and the downregulation of Snail, Slug, N-cadherin, and Vimentin at both mRNA and protein levels, in silico prediction identified STAT3 as a target, validated by protein analysis showing that DH_31 significantly decreases STAT3 levels through ubiquitin-proteasomal degradation. Immunofluorescence and Western blot analysis confirmed that DH_31 significantly decreased STAT3 and EMT markers. Additionally, molecular docking suggests a covalent interaction between the cyano group of DH_31 and Cys-468 in the DNA-binding domain of STAT3 (binding affinity = -7.630 kcal/mol), leading to destabilization thereafter. In conclusion, DH_31, a novel RT derivative, demonstrates potential as a STAT3-targeting drug that significantly contribute to understanding of the development of new targeted therapy.

ICAM1 (CD54) Contributes to the Metastatic Capacity of Gastric Cancer Stem Cells.

Gastric cancer is the fourth leading cause of cancer deaths worldwide. The presence of chemoresistant cells has been used to explain this high mortality rate. These higher tumorigenic and chemoresistant cells involve cancer stem cells (CSCs), which have the potential for self-renewal, a cell differentiation capacity, and a greater tumorigenic capacity. Our research group identified gastric cancer stem cells (GCSCs) with the CD24+CD44+CD326+ICAM1+ immunophenotype isolated from gastric cancer patients. Interestingly, this GCSC immunophenotype was absent in cells isolated from healthy people, who presented a cell population with a CD24+CD44+CD326+ immunophenotype, lacking ICAM1. We aimed to explore the role of ICAM1 in these GCSCs; for this purpose, we isolated GCSCs from the AGS cell line and generated a GCSC line knockout for ICAM1 using CRISPR/iCas9, which we named GCSC-ICAM1KO. To assess the role of ICAM1 in the GCSCs, we analyzed the migration, invasion, and chemoresistance capabilities of the GCSCs using in vitro assays and evaluated the migratory, invasive, and tumorigenic properties in a zebrafish model. The in vitro analysis showed that ICAM1 regulated STAT3 activation (pSTAT3-ser727) in the GCSCs, which could contribute to the ability of GCSCs to migrate, invade, and metastasize. Interestingly, we demonstrated that the GCSC-ICAM1KO cells lost their capacity to migrate, invade, and metastasize, but they exhibited an increased resistance to a cisplatin treatment compared to their parental GCSCs; the GCSC-ICAM1KO cells also exhibited an increased tumorigenic capability in vivo.

STING coordinates resolution of inflammation during wound repair by modulating macrophage trafficking through STAT3.

Efficient cutaneous wound healing requires a coordinated transition between inflammatory phases mediated by dynamic changes in leukocyte subset populations. Here, we identify STING as a key innate immune mediator governing timely resolution of inflammation by regulating macrophage dynamics during skin repair. Using a mouse model, we show STING deficiency caused delayed wound closure associated with abnormal persistence of TNF-α+ leukocytes. This resulted from the impaired macrophage recruitment. STING controlled the trafficking of bone marrow myeloid cells into blood and wounds, intrinsically enhancing macrophage migratory capacity through STAT3 activation. Specifically, STING modulated the production of monocyte chemokines and their receptors CCR2/CCR5 to enable efficient egress and wound infiltration. Consequently, disrupted systemic and local STING-STAT3-chemokine signaling combine to delay macrophage influx. This study elucidates STING as a critical rheostat tuning macrophage responses through STAT3 to orchestrate inflammatory resolution necessary for efficient wound healing. Our findings have broad implications for targeting STING therapeutically in both regenerative medicine and inflammatory disease contexts. STING regulates the macrophage trafficking through STAT3 in wound healing.

5-Fluorouracil resistance due to sphingosine kinase 2 overexpression in colorectal cancer is associated with myeloid-derived suppressor cell-mediated immunosuppressive effects.

Colorectal cancer (CRC) is one of the top five cancer-related causes of mortality globally. Acquired resistance has hindered the effectiveness of 5-fluorouracil (5-FU), the main chemotherapeutic drug used to treat CRC. Sphingosine kinase 2 (SphK2) may be a cancer treatment target and involved in 5-FU resistance. Cell growth was examined using MTT and clone formation assays for SphK2 expression. To identify immune cells in mice, flow cytometry was performed. West blotting demonstrated alterations in cell division and inflammation-related proteins. SphK2 levels and inflammation-related variables were studied using Elisa. Due to SphK2 overexpression, immunosuppression, and 5-FU resistance are caused by the development of myeloid-derived suppressor cells (MDSCs) subsequent to IL-6/STAT3 activation and alterations in the arginase (ARG-1) protein. After therapy, the combination of SphK2 inhibitors and 5-FU can effectively suppress MDSCs while increasing CD4+ and CD8+ T cell infiltration into the tumor microenvironment, lowering tumor burden, and exhibiting a therapeutic impact on CRC. Our findings suggest that 5-FU treatment combined with simultaneous Spkh2 inhibition by ABC294640 has anti-tumor synergistic effects by influencing multiple effects on tumor cells, T cells, and MDSCs, potentially improving the poor prognosis of colorectal cancer patients.

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.

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.

Deciphering the impact of STAT3 activation mediated by PTPRT promoter hypermethylation as biomarker of response to paclitaxel-plus-cetuximab in patients with recurrent or metastatic squamous cell carcinoma of the head and neck.

Squamous cell carcinoma of the head and neck (SCCHN) is an aggressive disease with poor prognosis. It is known that the activation of STAT3 signaling pathways promotes the development and progression of this neoplasia and it has been described the role of PTPRT as a negative regulator of STAT3. Then, we have evaluated the impact of them as biomarkers of outcome in a series of patients with recurrent and/or metastatic SCCHN treated with weekly paclitaxel-plus-cetuximab (ERBITAX) regimen. Between 2008 and 2017, 52 patients with recurrent/metastatic SCCHN were treated with ERBITAX at our center, 34 of whom had available tumor samples. Phosphorylated STAT3 (pSTAT3) protein expression was analyzed by immunohistochemistry, STAT3 mRNA expression by qPCR, and PTPRT promoter methylation by methylation-specific PCR. Molecular results were correlated with response rate (RR), progression-free survival (PFS), and overall survival (OS). pSTAT3 overexpression was detected in 67% and PTPRT promoter hypermethylation in 41% of tumor samples. PTPRT promoter hypermethylation showed a trend towards an association with lower RR (21% vs. 60%; p = 0.06). A lower RR was also observed in patients with pSTAT3 overexpression (36% vs. 54%) and in those with high STAT3 mRNA levels (43% vs. 64%), but these differences did not reach statistical significance. PTPRT promoter hypermethylation correlated with pSTAT3 overexpression (p = 0.009) but not with STAT3 mRNA overexpression. OS and PFS was shorter in patients with activated STAT3, but the difference did not reach statistical significance. Although this was a relatively small retrospective study, it provides preliminary indications of the potential role of the STAT3 pathway on outcome in SCCHN and confirms that PTPRT acts as a negative regulator of STAT3. Our findings warrant investigation in a larger patient cohort to determine if inactivating this pathway through specific targeted treatments could improve outcomes in recurrent/metastatic SCCHN patients.

Aptamin C enhances anti-cancer activity NK cells through the activation of STAT3: a comparative study with vitamin C.

Vitamin C is a well-known antioxidant with antiviral, anticancer, and anti-inflammatory properties based on its antioxidative function. Aptamin C, a complex of vitamin C with its specific aptamer, has been reported to maintain or even enhance the efficacy of vitamin C while increasing its stability. To investigate in vivo distribution of Aptamin C, Gulo knockout mice, which, like humans, cannot biosynthesize vitamin C, were administered Aptamin C orally for 2 and 4 weeks. The results showed higher vitamin C accumulation in all tissues when administered Aptamin C, especially in the spleen. Next, the activity of natural killer (NK) cells were conducted. CD69, a marker known for activating for NK cells, which had decreased due to vitamin C deficiency, did not recover with vitamin C treatment but showed an increasing with Aptamin C. Furthermore, the expression of CD107a, a cell surface marker that increases during the killing process of target cells, also did not recover with vitamin C but increased with Aptamin C. Based on these results, when cultured with tumor cells to measure the extent of tumor cell death, an increase in tumor cell death was observed. To investigate the signaling mechanisms and related molecules involved in the proliferation and activation of NK cells by Aptamin C showed that Aptamin C treatment led to an increase in intracellular STAT3 activation. In conclusion, Aptamin C has a higher capability to activate NK cells and induce tumor cell death compared to vitamin C and it is mediated through the activation of STAT3.

Biochemical characterization of Prokineticin 2 binding to Prokineticin receptor 1 in zebrafish

Prokineticin 2 (PK2) binds to prokineticin receptor 1 and prokineticin receptor 2 (PKR1 and PKR2, respectively), two G protein-coupled receptors (GPCRs) that can mediate multiple signalling pathways by promoting the elevation of intracellular calcium and cAMP levels, phosphorylation of Akt and activation of ERK and STAT3. This work aims to evidence the conservation of protein sequence and the mechanism of PK2 binding to PKR1 to use the zebrafish model for the identification of new drugs as targets of prokineticin receptors. To this end, we first demonstrated that the zebrafish genes pk2 and pkr1 are phylogenetically related to orthologous mammalian genes by constructing evolutionary trees and performing syntenic analyses. Subsequently, by comparing the amino acid sequences, we showed that the interaction sites with PK2 are conserved in the zPKR1. Using GST pull-down and cross-linking experiments, we demonstrated the crucial role of the N-terminal region of zPKR1 for binding to the PK2. Finally, by expressing zPKR1 in CHO cells, we demonstrated the ability of zPKR1 to induce the activation of ERK and STAT3.

STAT3 Regulates the Redox Profile in MDA-MB-231 Breast Cancer Cells.

Unbalanced redox status and constitutive STAT3 activation are related to several aspects of tumor biology and poor prognosis, including metastasis and drug resistance. The triple-negative breast cancer (TNBC) is listed as the most aggressive and exhibits the worst prognosis among the breast cancer subtypes. Although the mechanism of reactive oxygen species (ROS) generation led to STAT3 activation is described, there is no data concerning the STAT3 influence on redox homeostasis in TNBC. To address the role of STAT3 signaling in redox balance, we inhibited STAT3 in TNBC cells and investigated its impact on total ROS levels, contents of hydroperoxides, nitric oxide (NO), and total glutathione (GSH), as well as the expression levels of 3-nitrotyrosine (3NT), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and nuclear factor kappa B (NF-κB)/p65. Our results indicate that ROS levels depend on the STAT3 activation, while the hydroperoxide level remained unchanged, and NO and 3NT expression increased. Furthermore, GSH levels, Nrf2, and NF-κB/p65 protein levels are decreased in the STAT3-inhibited cells. Accordingly, TNBC patients' data from TCGA demonstrated that both STAT3 mRNA levels and STAT3 signature are correlated to NF-κB/p65 and Nrf2 signatures. Our findings implicate STAT3 in controlling redox balance and regulating redox-related genes' expression in triple-negative breast cancer.

Mesenchymal stem cells-derived extracellular vesicles ameliorate lupus nephritis by regulating T and B cell responses

BackgroundHuman umbilical cord mesenchymal stem cells-derived extracellular vesicles (hUCMSC-EVs) have potent immunomodulatory properties similar to parent cells. This study investigated the therapeutic effects and immunomodulatory mechanisms of hUCMSC-EVs in an experimental lupus nephritis model.MethodsThe hUCMSC-EVs were isolated by using differential ultracentrifugation. In vivo, the therapeutic effects of hUCMSC-EVs in lupus-prone MRL/lpr mice were investigated, and the mechanisms of treatment were explored according to the abnormal T and B cell responses among both the spleen and kidney.ResultsMRL/lpr mice treated with hUCMSC-EVs reduced proteinuria extent, serum creatinine and renal pathological damage; decreased splenic index and serum anti-dsDNA IgG level; and improved survival rate. hUCMSC-EVs lowered the percentage of T helper (Th)1 cells, double-negative T (DNT) cells, and plasma cells among splenocytes; inhibited the infiltration of Th17 cells but promoted regulatory T (Treg) cells in the kidney, followed by a reduction in pro-inflammatory cytokine levels(IFN-γ, IL-2, IL-6, IL-21, and IL-17 A). In addition, hUCMSC-EVs inhibited the activation of STAT3 and down-regulated IL-17 A protein levels in the kidney.ConclusionThe results of this study demonstrated that hUCMSC-EVs had therapeutic effects on experimental lupus nephritis (LN) by regulating Th1/Th17/Treg imbalance and inhibiting DNT and plasma cells. Additionally, hUCMSC-EVs inhibited Th17 cell differentiation in kidney by regulating the IL-6/STAT3/IL-17 signal pathway, which might be an important mechanism for alleviating renal injury. Taken together, we demonstrated that hUCMSC-EVs regulating T and B cell immune responses might represent a novel mechanism of hUCMSCs in treating LN, thus providing a new strategy for treating LN.

MRAP2a Binds and Modulates Activity and Localisation of Prokineticin Receptor 1 in Zebrafish.

The prokineticin system plays a role in hypothalamic neurons in the control of energy homeostasis. Prokineticin receptors (PKR1 and PKR2), like other G-protein-coupled receptors (GPCRs) are involved in the regulation of energy intake and expenditure and are modulated by the accessory membrane protein 2 of the melanocortin receptor (MRAP2). The aim of this work is to characterise the interaction and regulation of the non-melanocortin receptor PKR1 by MRAP2a in zebrafish (zMRAP2a) in order to use zebrafish as a model for the development of drugs targeting accessory proteins that can alter the localisation and activity of GPCRs. To this end, we first showed that zebrafish PKR1 (zPKR1) is able to interact with both zMRAP2a and human MRAP2 (hMRAP2). This interaction occurs between the N-terminal region of zPKR1 and the C-terminal domain of zMRAP2a, which shows high sequence identity with hMRAP2 and a similar propensity for dimer formation. Moreover, we demonstrated that in Chinese hamster ovary (CHO) cells, zMRAP2a or hMRAP2 are able to modulate zPKR1 activation induced by zebrafish PK2 (zPK2) resulting in an impaired ERK and STAT3 activation.

Topical treatment of tyrosine kinase 2 inhibitor through borneol-embedded hydrogel: Evaluation for preventive, therapeutic, and Recurrent management of psoriasis

Psoriasis, an immune-mediated inflammatory skin disorder characterized by a chronically relapsing-remitting course, continues to be primarily managed through topical therapy. While oral administration of tyrosine kinase 2 inhibitors (TYK2i) stands as an effective approach for psoriasis treatment, the potential efficacy of topical application of TYK2i remains unexplored. Herein, the carbomer/alginic acid hydrogel is embedded with borneol (BO) as a new topical carrier of TYK2i for achieving enhanced transdermal permeation and anti-psoriasis efficacy. The hydrogel system, i.e., TYK2i-BO-gel, exhibits significantly improved preventative and therapeutic effects in mice models of psoriasiform dermatitis, as evidenced by phenotypical images, psoriasis severity score index (PSI), histology, immunohistochemical staining, and PCR analysis. Remarkably, TYK2i-BO-gel outperforms conventional topical corticosteroid therapy by significantly preventing psoriatic lesion recurrence as measured by a nearly 50 % reduction in ear thickness changes (p < 0.0001), PSI (p < 0.0001) and epidermal thickness (p < 0.05). Moreover, a strengthened anti-inflammatory effect caused by TYK2i-BO-gel is seen in a human skin explant model, implying its potential application for human patients. With the addition of BO, the TYK2i-BO-gel not only increases skin permeability but also inhibits the expression of antimicrobial peptides in keratinocytes and facilitates the anti-Th17 response of TYK2i with suppressed activation of STAT3. Therefore, this work represents the accessibility and effectiveness of TYK2i-BO-hydrogel as a new topical formulation for anti-psoriasis management and shows great potential for clinical application.

Loss of Tuberous Sclerosis Complex 2 confers inflammation via dysregulation of Nuclear factor kappa-light-chain-enhancer of activated B cells.

Aberrant activation of mTORC1 is clearly defined in TSC, causing uncontrolled cell growth. While mTORC1 inhibitors show efficacy to stabilise tumour growth in TSC, they are not fully curative. Disease facets of TSC that are not restored with mTOR inhibitors might involve NF-κB. The study aimed to characterise NF-κB in the context of TSC. Enrichment of NF-κB-regulated genes was observed in TSC patient tumours, SEN/SEGAs, cortical tubers and a TSC tumour-derived cell line (621 - 101). Highlighting an inflammatory component of TSC, TSC cell models showed an elevated level of NF-κB and STAT3 activation. Herein, we report a dysregulated inflammatory phenotype of TSC2-deficient cells where NF-κB promotes autocrine signalling involving IL-6. Of importance, mTORC1 inhibition does not block this inflammatory signal to promote STAT3, while NF-κB inhibition was much more effective. Combined mTORC1 and NF-κB inhibition was potent at preventing anchorage-independent growth of TSC2-deficient cells, and unlike mTORC1 inhibition alone was sufficient to prevent colony regrowth after cessation of treatment. This study reveals autocrine signalling crosstalk between NF-κB and STAT3 in TSC cell models. Furthermore, the data presented indicate that NF-κB pathway inhibitors could be a viable adjunct therapy with the current mTOR inhibitors to treat TSC.

Analysis of the Actions of RARγ Agonists on Growing Osteochondromas in a Mouse Model.

The actions of the retinoic acid nuclear receptor gamma (RARγ) agonist, palovarotene, on pre-existing osteochondromas were investigated using a mouse multiple osteochondroma model. This approach was based on the knowledge that patients often present to the clinic after realizing the existence of osteochondroma masses, and the findings from preclinical investigations are the effects of drugs on the initial formation of osteochondromas. Systemic administration of palovarotene, with increased doses (from 1.76 to 4.0 mg/kg) over time, fully inhibited tumor growth, keeping the tumor size (0.31 ± 0.049 mm3) similar to the initial size (0.27 ± 0.031 mm3, p = 0.66) while the control group tumor grew (1.03 ± 0.23 mm3, p = 0.023 to the drug-treated group). Nanoparticle (NP)-based local delivery of the RARγ agonist also inhibited the growth of osteochondromas at an early stage (Control: 0.52 ± 0.11 mm3; NP: 0.26 ± 0.10, p = 0.008). Transcriptome analysis revealed that the osteoarthritis pathway was activated in cultured chondrocytes treated with palovarotene (Z-score = 2.29), with the upregulation of matrix catabolic genes and the downregulation of matrix anabolic genes, consistent with the histology of palovarotene-treated osteochondromas. A reporter assay performed in cultured chondrocytes demonstrated that the Stat3 pathway, but not the Stat1/2 pathway, was stimulated by RARγ agonists. The activation of Stat3 by palovarotene was confirmed using immunoblotting and immunohistochemistry. These findings suggest that palovarotene treatment is effective against pre-existing osteochondromas and that the Stat3 pathway is involved in the antitumor actions of palovarotene.

Targeting CSF1R in myeloid-derived suppressor cells: insights into its immunomodulatory functions in colorectal cancer and therapeutic implications

ObjectiveThis study aimed to investigate the critical role of MDSCs in CRC immune suppression, focusing on the CSF1R and JAK/STAT3 signaling axis. Additionally, it assessed the therapeutic efficacy of LNCs@CSF1R siRNA and anti-PD-1 in combination.MethodsSingle-cell transcriptome sequencing data from CRC and adjacent normal tissues identified MDSC-related differentially expressed genes. RNA-seq analysis comprehensively profiled MDSC gene expression in murine CRC tumors. LNCs@CSF1R siRNA nanocarriers effectively targeted and inhibited CSF1R. Flow cytometry quantified changes in MDSC surface markers post-CSF1R inhibition. RNA-seq and pathway enrichment analyses revealed the impact of CSF1R on MDSC metabolism and signaling. The effect of CSF1R inhibition on the JAK/STAT3 signaling axis was validated using Colivelin and metabolic assessments. Glucose and fatty acid uptake were measured via fluorescence-based flow cytometry. The efficacy of LNCs@CSF1R siRNA and anti-PD-1, alone and in combination, was evaluated in a murine CRC model with extensive tumor section analyses.ResultsCSF1R played a significant role in MDSC-mediated immune suppression. LNCs@CSF1R siRNA nanocarriers effectively targeted MDSCs and inhibited CSF1R. CSF1R regulated MDSC fatty acid metabolism and immune suppression through the JAK/STAT3 signaling axis. Inhibition of CSF1R reduced STAT3 activation and target gene expression, which was rescued by Colivelin. Combined treatment with LNCs@CSF1R siRNA and anti-PD-1 significantly slowed tumor growth and reduced MDSC abundance within CRC tumors.ConclusionCSF1R via the JAK/STAT3 axis critically regulates MDSCs, particularly in fatty acid metabolism and immune suppression. Combined therapy with LNCs@CSF1R siRNA and anti-PD-1 enhances therapeutic efficacy in a murine CRC model, providing a strong foundation for future clinical applications.

Targeting HTR2B suppresses nonfunctioning pituitary adenoma growth and sensitizes cabergoline treatment via inhibiting Gαq/PLC/PKCγ/STAT3 axis.

Managing nonfunctioning pituitary adenomas (NFPAs) is difficult due to limited drug treatments. Cabergoline's (CAB) effectiveness for NFPAs is debated. This study explores the role of HTR2B in NFPAs and its therapeutic potential. We conducted screening of bulk RNA-sequencing data to analyze HTR2B expression levels in NFPA samples. In vitro and in vivo experiments were performed to evaluate the effects of HTR2B modulation on tumor growth and cell cycle regulation. Mechanistic insights into the HTR2B-mediated signaling pathway were elucidated using pharmacological inhibitors and molecular interaction assays. Elevated HTR2B expression was detected in NFPA samples, which was associated with increased tumor survival. Inhibition of HTR2B activity resulted in the suppression of tumor growth through modulation of the G2M cell cycle. The inhibition of HTR2B with PRX-08066 was found to block STAT3 phosphorylation and nuclear translocation by interfering with the Gαq/PLC/PKC pathway. A direct interaction between PKC-γ and STAT3 was critical for STAT3 activation. CAB was shown to activate pSTAT3 via HTR2B, reducing its therapeutic potential. However, the combination of an HTR2B antagonist with CAB significantly inhibited tumor cell proliferation in HTR2B-expressing pituitary tumor cell lines, a xenografted pituitary tumor model, and patient-derived samples. Analysis of patient-derived data indicated that a distinct molecular pattern characterized by upregulated HTR2B/PKC-γ and downregulated BTG2/GADD45A may benefit from combination treatment with CAB and PRX-08066. HTR2B is a potential therapeutic target for NFPAs, and its inhibition could improve CAB efficacy. A dual therapy approach may be beneficial for NFPA patients with high HTR2B expression.

Intratumoral injection of mRNA encoding survivin in combination with STAT3 inhibitor stattic enhances antitumor effects

Intratumoral delivery of mRNA encoding immunostimulatory molecules can initiate a robust, global antitumor response with little side effects by enhancing local antigen presentation in the tumor and the tumor draining lymph node. Neoantigen-based mRNA nanovaccine can inhibit melanoma growth in mice by intratumoral injection. Myeloid-derived suppressor cells (MDSCs) suppress antitumor immune responses by secreting immunosuppressive agents, such as reactive oxygen species (ROS). Suppression of STAT3 activity by stattic may reduce MDSC-mediated immunosuppression in the TME and promote the antitumor immune responses. In this study, in vitro transcribed mRNA encoding tumor antigen survivin was prepared and injected intratumorally in BALB/c mice bearing subcutaneous colon cancer tumors. In vivo studies demonstrated that intratumoral survivin mRNA therapy could induce antitumor T cell response and inhibit tumor growth of colon cancer. Depletion of CD8+ T cells could significantly inhibit survivin mRNA-induced antitumor effects. RT-qPCR and ELISA analysis indicated that survivin mRNA treatment led to increased expression of receptor activator nuclear factor-κB ligand (RANKL). In vitro experiment showed that MDSCs could be induced from mouse bone marrow cells by RANKL and RANKL-induced MDSCs could produce high level of ROS. STAT3 inhibitor stattic suppressed activation of STAT3 and NF-κB signals, thereby inhibiting expansion of RANKL-induced MDSCs. Combination therapy of survivin mRNA and stattic could significantly enhance antitumor T cell response, improve long-term survival and reduce immunosuppressive tumor microenvironment compared to each monotherapy. In addition, combined therapy resulted in a significantly reduced level of tumor cell proliferation and an obviously increased level of tumor cell apoptosis in CT26 colon cancer-bearing mice, which could be conducive to inhibit the tumor growth and lead to immune responses to released tumor-associated antigens. These studies explored intratumoral mRNA therapy and mRNA-based combined therapy to treat colon cancer and provide a new idea for cancer therapy.

Targeting STAT3 Enzyme for Cancer Treatment.

A category of cytoplasmic transcription factors called STATs mediates intracellular signaling, which is frequently generated at receptors on cell surfaces and subsequently sent to the nucleus. STAT3 is a member of a responsible for a variety of human tumor forms, including lymphomas, hematological malignancies, leukemias, multiple myeloma and several solid tumor types. Numerous investigations have demonstrated constitutive STAT3 activation lead to cancer development such as breast, head and neck, lung, colorectal, ovarian, gastric, hepatocellular, and prostate cancers. It's possible to get a hold of the book here. Tumor cells undergo apoptosis when STAT3 activation is suppressed. This review highlights the STAT3 activation and inhibition which can be used for further studies.

SIPA1 promotes epithelial-mesenchymal transition in colorectal cancer through STAT3 activation

Colorectal cancer (CRC) is the third leading cancer type worldwide and accounts for the second highest rate of cancer-related mortality. Liver metastasis significantly contributes to the mortality associated with CRC, but the fundamental mechanisms behind it remain unclear. Signal-induced proliferation-associated protein 1 (SIPA1), a GTPase activating protein, has been shown to promote metastasis in breast cancer. In this study, our objective was to explore the role of SIPA1 in regulating epithelial-mesenchymal transition (EMT) in CRC. The analysis of The Cancer Genome Atlas (TCGA) database revealed that the expression level of SIPA1 mRNA was notably upregulated and exhibited a positively correlated with EMT and STAT3 signaling pathways in CRC. Knockdown of SIPA1 impairs CRC cell proliferation and migration. Further studies on the reliance of SIPA1 on STAT3 signaling for EMT regulation have shown that SIPA1 stimulates the activation of STAT3, resulting in its nuclear translocation. The co-treatment of overexpressed SIPA1 with the STAT3 inhibitor STTITA has shown that SIPA1 regulates the expression of EMT-related markers through STAT3. Our study indicate that SIPA1 promotes CRC metastasis by activating the STAT3 signaling pathway, underscoring the potential of SIPA1 as a therapeutic target for metastatic CRC patients.