Signal Transducer And Activator Of Transcription 3 Inhibitor Research Articles

TMET-03. ONCOGENIC STAT3 PROMOTES TUMOR GROWTH VIA STIMULATION THE SCAP- AND SREBP-1-REGULATED LIPOGENIC PATHWAY

Abstract Augmented lipogenesis is a hallmark of cancer. In addition, signal transducer and activator of transcription 3 (STAT3) is aberrantly activated and associated with poor prognosis in multiple cancers. Whether oncogenic STAT3 has an intrinsic and causal link to lipogenesis in cancer remains unclear. Here, we show that inhibition of STAT3 significantly alters the lipid profile of tumor cells, including free fatty acids and derived membrane structural phospholipids (phosphatidic acid, phosphatidylinositol, phosphatidylserine and sphingomyelin), this change results in cell death which could be rescued by lipids (oleic acid and palmitoleic acid) supplementation, while suppressing the gene and protein expression of major mediators of the lipogenic pathway including sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP), SREBP-1, fatty acid synthase and stearoyl-CoA desaturase 1. Furthermore, we show that STAT3 binds the promoter of SCAP, SREBP-1a and SREBP-1c, to promote their transcription in tumor cells. Finally, targeting STAT3 in a xenograft mouse model blocked glioblastoma growth and lipogenic enzyme expression. Our study reveals a novel regulatory pathway of STAT3-SCAP/SREBP-1 involved in tumor growth in vitro and in vivo, connecting STAT3 signaling with SCAP- and SREBP-1-mediated lipogenesis.

Probing the Depths of Molecular Complexity: STAT3 as a Key Architect in Colorectal Cancer Pathogenesis.

Colorectal cancer (CRC) has become a significant threat in recent decades, and its incidence is predicted to continue rising. Despite notable advancements in therapeutic strategies, managing CRC poses complex challenges, primarily due to the lack of clinically feasible therapeutic targets. Among the myriad molecules implicated in CRC, the signal transducer and activator of transcription 3 (STAT3) stands out as a promising target tightly regulated by various genes. This intracellular transcription factor, spanning 750-795 amino acids and weighing approximately 92 kDa, is crucial in key cellular activities such as growth, migration, invasion, inflammation, and angiogenesis. Aberrant activation of STAT3 signaling has been linked to various cancers, including CRC. Therefore, targeting this signaling pathway holds significance for potential CRC treatment strategies.STAT3, as a central intracellular transcription factor, is implicated in colorectal cancer development by activating aberrant signaling pathways. Numerous studies have demonstrated that the abnormal hyperactivation of STAT3 in CRC tissues enhances cell proliferation, suppresses apoptosis, promotes angiogenesis, and facilitates tumor invasion and metastasis. As a focal point in colorectal cancer research, STAT3 emerges as a promising candidate for detecting and treating CRC. This review aims to present recent data on STAT3, emphasizing the activation and functions of STAT3 inhibitors in CRC. Indeed, STAT3 inhibitors have been identified to have therapeutic potential in CRC, especially inhibitors targeting the DNA-binding domain (DBD). Indeed, STAT3 inhibitors have been identified to have a therapeutic potential in CRC, especially the inhibitors targeting the DNA binding domain (DBD). For example, imatinib acts by targeting cell surface receptors, and these inhibitors have shown potential for the control and treatment of tumor growth, angiogenesis, and metastasis. Imatinib, for example acts by targeting cell surface receptors, and these inhibitors have shown the future direction toward the control and treatment of tumor growth, angiogenesis, and metastasis.

Suppressing Pancreatic Cancer Survival and Immune Escape via Nanoparticle-Modulated STING/STAT3 Axis Regulation.

Pancreatic ductal adenocarcinoma (PDAC) poses a challenge in oncology due to its high lethality and resistance to immunotherapy. Recently, emerging research on the stimulator of interferon gene (STING) pathway offers novel opportunities for immunotherapy. Although STING expression is retained in PDAC cells, the response of PDAC cells to STING agonists remains ineffective. Signal transducer and activator of transcription 3 (STAT3), a downstream pathway of STING, is notably overexpressed in pancreatic cancer and related to tumor survival and immune escape. We observed that inhibiting STAT3 signaling post-STING activation effectively suppressed tumor growth through signal transducer and activator of transcription 1 (STAT1)-mediated apoptosis but led to a potential risk of immune-related adverse events (irAEs). To address this issue, we designed a tumor-penetrating liposome for the codelivery of STING agonist and STAT3 inhibitor. These nanoparticles regulated the STING/STAT3 signaling axis and effectively inhibited the proliferation and survival of tumor. Simultaneously, we found a significant increase in the activation of NK cells and CD8+ T cells after treatment, leading to robust innate immunity and adaptive immune response. We highlight the potential of regulating the STING/STAT3 axis as a promising treatment for improving clinical outcomes in PDAC patients.

MiR-191-5p suppresses PRRSV replication by targeting porcine EGFR to enhance interferon signaling.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major thread to the global swine industry, lack of effective control strategies. This study explores the regulatory role of a small non-coding RNA, miR-191-5p, in PRRSV infection. We observed that miR-191-5p significantly inhibits PRRSV in porcine alveolar macrophages (PAMs), contrasting with negligible effects in MARC-145 and HEK293-CD163 cells, suggesting a cell-specific antiviral effect. Further investigation unveiled that miR-191-5p directly targets the porcine epidermal growth factor receptor (EGFR), whose overexpression or EGF-induced activation suppresses type I interferon (IFN-I) signaling, promoting PRRSV replication. In contrast, siRNA-or miR-191-5p-induced EGFR downregulation or EGFR inhibitor boosts IFN-I signaling, reducing viral replication. Notably, this miRNA alleviates the suppressive effect of EGF on IFN-I signaling, underscoring its regulatory function. Further investigation revealed interconnections among miR-191-5p, EGFR and signal transducer and activator of transcription 3 (STAT3). Modulation of STAT3 activity influenced IFN-I signaling and PRRSV replication, with STAT3 knockdown countering EGFR activation-induced virus replication. Combination inhibition of STAT3 and miR-191-5p suggests that STAT3 acts downstream in EGFR's antiviral response. Furthermore, miR-191-5p's broad efficacy in restricting various PRRSV strains in PAMs was identified. Collectively, these findings elucidate a novel mechanism of miR-191-5p in activating host IFN-I signaling to inhibit PRRSV replication, highlighting its potential in therapeutic applications against PRRSV.

Design, synthesis, and biological evaluation of novel 5,7,4′-trimethoxyflavone sulfonamide-based derivatives as highly potent inhibitors of LRPPRC/STAT3/CDK1

Leucine-rich pentatricopeptide repeat-containing protein (LRPPRC), signal transducer and activator of transcription 3 (STAT3), and cyclin-dependent kinase 1 (CDK1) are promising therapeutic targets for cancer treatment. However, there is a lack of effective inhibitors of LRPPRC, STAT3, and CDK1 in clinic. Our previous study has proved that 5,7,4′-Trimethoxyflavone (TMF) is a novel inhibitor of LRPPRC/STAT3/CDK1. However, the extraction rate of TMF from Tangerine Peel is quite low, and the doses of TMF in cells and mice are rather high. Herein, structural modifications of TMF have led to two series of TMF derivatives including sulfonamide substituted at 3′-position (7a–m) and 3′,8-position (11a–m). Among all compounds, 7e, 7k, 11e, and 11g exhibited as effective, broad-spectrum, and potent anticancer agents in vitro. Moreover, 7e, 7k, 11e, and 11g showed better antitumor effects than TMF and clinical used chemotherapy drug capecitabine in vivo with no obvious toxicity. Mechanism studies showed that 11g could bind to LRPPRC, STAT3, and CDK1 to disassociate the LRPPRC-JAK2-STAT3 and JAK2-STAT3-CDK1 complexes, resulting in suppression of JAK2/STAT3 signaling pathway. These findings suggest that 11g may serve as a leading compound for cancer therapy as a triple-target (LRPPRC, STAT3, and CDK1) inhibitor.

Inhibition of STAT3 by 2-Methoxyestradiol suppresses M2 polarization and protumoral functions of macrophages in breast cancer

BackgroundBreast cancer metastasis remains the leading cause of cancer-related deaths in women worldwide. Infiltration of tumor-associated macrophages (TAMs) in the tumor stroma is known to be correlated with reduced overall survival. The inhibitors of TAMs are sought after for reprogramming the tumor microenvironment. Signal transducer and activator of transcription 3 (STAT3) is well known to contribute in pro-tumoral properties of TAMs. 2-Methoxyestradiol (2ME2), a potent anticancer and antiangiogenic agent, has been in clinical trials for treatment of breast cancer. Here, we investigated the potential of 2ME2 in modulating the pro-tumoral effects of TAMs in breast cancer.MethodsTHP-1-derived macrophages were polarized to macrophages with or without 2ME2. The effect of 2ME2 on macrophage surface markers and anti-inflammatory genes was determined by Western blotting, flow cytometry, immunofluorescence, qRT‒PCR. The concentration of cytokines secreted by cells was monitored by ELISA. The effect of M2 macrophages on malignant properties of breast cancer cells was determined using colony formation, wound healing, transwell, and gelatin zymography assays. An orthotopic model of breast cancer was used to determine the effect of 2ME2 on macrophage polarization and metastasis in vivo.ResultsFirst, our study found that polarization of monocytes to alternatively activated M2 macrophages is associated with the reorganization of the microtubule cytoskeleton. At lower concentrations, 2ME2 treatment depolymerized microtubules and reduced the expression of CD206 and CD163, suggesting that it inhibits the polarization of macrophages to M2 phenotype. However, the M1 polarization was not significantly affected at these concentrations. Importantly, 2ME2 inhibited the expression of several anti-inflammatory cytokines and growth factors, including CCL18, TGF-β, IL-10, FNT, arginase, CXCL12, MMP9, and VEGF-A, and hindered the metastasis-promoting effects of M2 macrophages. Concurrently, 2ME2 treatment reduced the expression of CD163 in tumors and inhibited lung metastasis in the orthotopic breast cancer model. Mechanistically, 2ME2 treatment reduced the phosphorylation and nuclear translocation of STAT3, an effect which was abrogated by colivelin.ConclusionsOur study presents novel findings on mechanism of 2ME2 from the perspective of its effects on the polarization of the TAMs via the STAT3 signaling in breast cancer. Altogether, the data supports further clinical investigation of 2ME2 and its derivatives as therapeutic agents to modulate the tumor microenvironment and immune response in breast carcinoma.

Stat3 Inhibitors TTI-101 and SH5-07 Suppress Bladder Cancer Cell Survival in 3D Tumor Models.

Bladder cancer (BCa) is one of the most lethal genitourinary malignancies owing to its propensity for recurrence and poor survival. The biochemical pathway, signal transducer and activator of transcription 3 (STAT3), has gained significance as a molecular pathway that promotes proliferation, invasion, and chemoresistance. In this study, we explored the targeting of STAT3 with TTI-101 and SH5-07 in BCa and elucidated the mechanisms in three-dimensional (3D) spheroid and organoid models. We optimized the growth of spheroids from human, rat, and mouse BCa cell lines (J82, NBT-II, and MB49 respectively) and organoids from BBN (N-butyl-N-(4-hydroxybutyl)-nitrosamine)-induced rat bladder tumors. Cell viability was assessed using MTT and trypan blue assays. Intracellular ATP production, ROS production, and calcium AM (CA)/EtBr staining were used to measure the spheroid and organoid inhibition and mitochondrial function. Western blot analysis was performed to evaluate the pharmacodynamic markers involved in cell proliferation, apoptosis, cancer stem cells (CSCs), and STAT3 signaling in BCa. We found that targeting STAT3 (using TTI-101 and SH5-07) significantly reduced the proliferation of BCa spheroids and organoids, which was accompanied by decreased expression of pSTAT3, Cyclin D1, and PCNA. Our data also demonstrated that treatment with STAT3 inhibitors induced ROS production and cell death in BCa spheroids and organoids. STAT3 inhibition-induced cell death was associated with the activation of caspase 3/7 and PARP cleavage. Moreover, TTI-101 and SH5-07 target cancer stem cells by downregulating the expression of CD44 and CD133 in 3D models. This study provides the first evidence for the prevention of BCa with small-molecule inhibitors TTI-101 and SH5-07 via suppression of CSCs and STAT3 signaling.

STAT3 Increases CVB3 Replication and Acute Pancreatitis and Myocarditis Pathology via Impeding Nuclear Translocation of STAT1 and Interferon-Stimulated Gene Expression.

Acute pancreatitis (AP) is an inflammatory disease initiated by the death of exocrine acinar cells, but its pathogenesis remains unclear. Signal transducer and activator of transcription 3 (STAT3) is a multifunctional factor that regulates immunity and the inflammatory response. The protective role of STAT3 is reported in Coxsackievirus B3 (CVB3)-induced cardiac fibrosis, yet the exact role of STAT3 in modulating viral-induced STAT1 activation and type I interferon (IFN)-stimulated gene (ISG) transcription in the pancreas remains unclarified. In this study, we tested whether STAT3 regulated viral-induced STAT1 translocation. We found that CVB3, particularly capsid VP1 protein, markedly upregulated the phosphorylation and nuclear import of STAT3 (p-STAT3) while it significantly impeded the nuclear translocation of p-STAT1 in the pancreases and hearts of mice on day 3 postinfection (p.i.). Immunoblotting and an immunofluorescent assay demonstrated the increased expression and nuclear translocation of p-STAT3 but a blunted p-STAT1 nuclear translocation in CVB3-infected acinar 266-6 cells. STAT3 shRNA knockdown or STAT3 inhibitors reduced viral replication via the rescue of STAT1 nuclear translocation and increasing the ISRE activity and ISG transcription in vitro. The knockdown of STAT1 blocked the antiviral effect of the STAT3 inhibitor. STAT3 inhibits STAT1 activation by virally inducing a potent inhibitor of IFN signaling, the suppressor of cytokine signaling-3 ((SOCS)-3). Sustained pSTAT1 and the elevated expression of ISGs were induced in SOCS3 knockdown cells. The in vivo administration of HJC0152, a pharmaceutical STAT3 inhibitor, mitigated the viral-induced AP and myocarditis pathology via increasing the IFNβ as well as ISG expression on day 3 p.i. and reducing the viral load in multi-organs. These findings define STAT3 as a negative regulator of the type I IFN response via impeding the nuclear STAT1 translocation that otherwise triggers ISG induction in infected pancreases and hearts. Our findings identify STAT3 as an antagonizing factor of the IFN-STAT1 signaling pathway and provide a potential therapeutic target for viral-induced AP and myocarditis.

Homocysteine Promotes Intestinal Inflammation in Colitis Mice Through the PGE2/STAT3 Signaling Pathway.

Our previous study indicated that Hcy exacerbated DSS-induced colitis by facilitating the differentiation of intestinal T helper cell 17 (Th17), but the precise mechanism remains unidentified. Therefore, our current research aims to elucidate the signaling pathway through which Hcy promotes the differentiation of Th17 cells. BALb/c mice were randomly assigned into six groups. The model of mice colitis was induced using 3% DSS, while the model of Hyperhomocysteinemia was induced using 1.7% methionine. The concentrations of Hcy and prostaglandin E2 (PGE2) were measured using enzyme-linked immunosorbent assay (ELISA). The protein expressions of cytosolic phospholipase A2 (cPLA2), phosphorylated-cPLA2 (p-cPLA2), cyclooxygenase 2 (COX2), cyclic adenosine monophosphate (cAMP), signal transducer and activator of transcription 3 (STAT3), phosphorylated-STAT3 (p-STAT3), interleukin-17A (IL-17A), and retinoid-related orphan nuclear receptor-γt (RORγt) were assessed using western blot analysis. Compared to the DSS + HHcy group, the addition of the COX inhibitor did not significantly alter the protein expression of p-PLA2/PLA2, but led to significant decreases in serum PGE2 concentration, cAMP, and p-STAT3/STAT3 protein expression. The protein expressions of p-PLA2/PLA2, COX2, and cAMP upstream of STAT3 inhibitor addition did not exhibit significant changes. However, PGE2 concentration and p-STAT3/STAT3 protein expression were notably reduced. After the COX inhibitor and STAT3 inhibitor added, the protein expression of IL-17A and RORγt and the levels of IL-17A and IL-23R in CD4+ T cells were significantly reduced. HHcy aggravated DSS-induced colitis by promoting the differentiation and proliferation of Th17 cells through the PGE2 / STAT3 signaling pathway.

TTI-101 targets STAT3/c-Myc signaling pathway to suppress cervical cancer progression: an integrated experimental and computational analysis

BackgroundCervical cancer (CC) is a significant global health concern, demanding the consideration of novel therapeutic strategies. The signal transducer and activator of transcription 3 (STAT3) pathway has been implicated in cancer progression and is a potential target for therapeutic intervention. This study aimed to explore the therapeutic potential of TTI-101, a small molecule STAT3 inhibitor, in CC and investigate its underlying mechanisms.MethodsMolecular docking studies and molecular dynamics simulations were performed to explore the binding interaction between TTI-101 and STAT3 and assess the stability of the STAT3-TTI-101 complex. Cell viability assays, wound healing assays, colony formation assays, flow cytometry analysis, and gene expression analysis were conducted. In vivo xenograft models were used to assess the antitumor efficacy of TTI-101.ResultsThe in silico analysis shows a stable binding interaction between TTI-101 and STAT3. TTI-101 treatment inhibits cell viability, clonogenic ability, and cell migration in CC cells. Furthermore, TTI-101 induces apoptosis and cell cycle arrest. Analysis of apoptosis-related markers demonstrated dysregulation of Bax, Bcl-2, and Caspase-3 upon TTI-101 treatment. Moreover, TTI-101 caused G2/M phase arrest accompanied by a decrease in CDK1 and Cyclin B1 at mRNA levels. In the xenograft model, TTI-101 significantly inhibited tumor growth without adverse effects on body weight.ConclusionTTI-101 exhibited anticancer effects by targeting the STAT3/c-Myc signaling pathway, inducing cell cycle arrest, and promoting apoptosis in CC cells. These findings provide valuable insights into the development of novel therapeutic strategies for cervical cancer. Further investigation is warranted to validate the clinical application of TTI-101.Graphical

Evaluation of STAT3 Inhibition by Cancer Chemopreventive Trichothecenes Derived from Metabolites of Trichothecium roseum.

This study evaluated the ability of isolated or semisynthesized trichothecene sesquiterpenes to prevent cancer emergence and proliferation and inhibit signal transducer and activator of transcription-3 (STAT3) phosphorylation through in vitro assays. Trichothecinol A (TTC-A), which bears a hydroxy group at C3, exhibited greater cancer prevention, antiproliferation, and STAT3 phosphorylation inhibition effects than trichothecin (TTC), which lacks a hydroxy group at C3. Furthermore, trichothecinol B (TTC-B), which is a reduced derivative of TTC and has similar cytotoxic effect, showed substantially weaker chemoprotection and STAT3 phosphorylation inhibition effects than TTC. These results clearly indicate that the hydroxy group at C3 and carbonyl group at C8 are crucial for inducing both potent chemoprevention and STAT3 phosphorylation inhibition.

Bi-functional CpG-STAT3 decoy oligonucleotide triggers multilineage differentiation of acute myeloid leukemia in mice

Acute myeloid leukemia (AML) cells resist differentiation stimuli despite high expression of innate immune receptors, such as Toll-like receptor 9 (TLR9). We previously demonstrated that targeting Signal Transducer and Activator of Transcription 3 (STAT3) using TLR9-targeted decoy oligodeoxynucleotide (CpG-STAT3d) increases immunogenicity of human and mouse AML cells. Here, we elucidated molecular mechanisms of inv(16) AML reprogramming driven by STAT3-inhibition/TLR9-activation invivo. At the transcriptional levels, AML cells isolated from mice after intravenous administration of CpG-STAT3d or leukemia-targeted Stat3 silencing and TLR9 co-stimulation, displayed similar upregulation of myeloid cell differentiation (Irf8, Cebpa, Itgam) and antigen-presentation (Ciita, Il12a, B2m)-related genes with concomitant reduction of leukemia-promoting Runx1. Single-cell transcriptomics revealed that CpG-STAT3d induced multilineage differentiation of AML cells into monocytes/macrophages, erythroblastic and B cell subsets. As shown by an inducible Irf8 silencing invivo, IRF8 upregulation was critical for monocyte-macrophage differentiation of leukemic cells. TLR9-driven AML cell reprogramming was likely enabled by downregulation of STAT3-controlled methylation regulators, such as DNMT1 and DNMT3. In fact, the combination of DNA methyl transferase (DNMT) inhibition using azacitidine with CpG oligonucleotides alone mimicked CpG-STAT3d effects, resulting in AML cell differentiation, Tcell activation, and systemic leukemia regression. These findings highlight immunotherapeutic potential of bi-functional oligonucleotides to unleash TLR9-driven differentiation of leukemic cells by concurrent STAT3 and/or DNMT inhibition.

Anti-tumor withanolides as signal transducers and activators of transcription 3 (STAT3)-inhibition from Withania obtusifolia

The Solanaceae family and the Withania genus specifically are rich sources of medicinal plants. Liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS/MS) revealed a predominance of withanolides from an organic extract of Withania obtusifolia. A constructed molecular network uncovered the presence of potentially novel withanolides. A series of withanolides were then isolated and structurally characterized from the extract including two new withanolides (withafolia A and withafolia B) and seven previously reported metabolites. Of the isolated compounds, cytotoxicity of withanolide J, physaperuvin G, and a commercial STAT3 inhibitor (S3I-201) were assessed against a human leukemia HL-60 cell line resulting in IC50 values of 26, 29, and 120 μM, respectively. In silico molecular docking simulations indicate that withanolide J and physaperuvin G can bind as an inhibitor in the active site of STAT3 with docking scores comparable to the selective STAT3 inhibitor, S3I-201.

Selective STAT3 inhibitor STX-0119 alleviates osteoarthritis progression by modulating the STAT3/PPARγ signaling pathway

Osteoarthritis (OA), characterized by chronic pain, significantly affects the quality of life of affected individuals. Key factors in OA pathogenesis include cartilage degradation and inflammation. Signal transducer and activator of transcription 3 (STAT3), a member of the STAT protein family, plays a pivotal role in mediating inflammation. STX-0119 has been verified as a small molecular compound that can specifically inhibit STAT3. However, the efficacy of STX-0119 in the treatment of OA remains to be evaluated. Therefore, the aim of this study was to explore the therapeutic effects and molecular mechanisms of STX-0119 in the treatment of OA. We found that the expression of phosphorylated STAT3 is upregulated in human OA cartilage as well as in the cartilage of a mouse model of OA. In vivo, joint injection of STX-0119 into OA mice alleviated cartilage degeneration without affecting the subchondral bone. Additionally, STX-0119 could inhibit the phosphorylation of STAT3 in the cartilage. In vitro, STX-0119 suppressed inflammatory responses in chondrocytes and promoted anabolic metabolism in an interleukin-1β-induced chondrocyte inflammation model. Additionally, the results of transcriptome sequencing and lentiviral infection assays demonstrated that in chondrocytes, STX-0119 induces the upregulation of peroxisome proliferators-activated receptor gamma (PPARγ) expression by inhibiting STAT3 phosphorylation. Finally, in ex vivo cultures of human cartilage samples, STX-0119 was reaffirmed to inhibit cartilage degeneration via the STAT3/PPARγ signaling pathway. Together, our findings support the potential of STX-0119 for development as a therapeutic agent targeting STAT3 for the treatment of OA.

Plakevulin A induces apoptosis and suppresses IL-6-induced STAT3 activation in HL60 cells

(+)-Plakevulin A (1), an oxylipin isolated from an Okinawan sponge Plakortis sp. inhibits enzymatic inhibition of DNA polymerases (pols) α and δ and exhibits cytotoxicity against murine leukemia (L1210) and human cervix carcinoma (KB) cell lines. However, the half-maximal inhibitory concentration (IC50) value for cytotoxicity significantly differed from those observed for the enzymatic inhibition of pols α and β, indicating the presence of target protein(s) other than pols. This study demonstrated cytotoxicity against human promyelocytic leukemia (HL60), human cervix epithelioid carcinoma (HeLa), mouse calvaria-derived pre-osteoblast (MC3T3-E1), and human normal lung fibroblast (MRC-5) cell lines. This compound had selectivity to cancer cells over normal ones. Among these cell lines, HL60 exhibited the highest sensitivity to (+)-plakevulin A. (+)-Plakevulin A induced DNA fragmentation and caspase-3 activation in HL60 cells, indicating its role in apoptosis induction. Additionally, hydroxysteroid 17-β dehydrogenase 4 (HSD17B4) was isolated from the HL60 lysate as one of its binding proteins through pull-down experiments using its biotinylated derivative and neutravidin-coated beads. Moreover, (+)-plakevulin A suppressed the activation of interleukin 6 (IL-6)-induced signal transducer and activator of transcription 3 (STAT3). Because the knockdown or inhibition of STAT3 induces apoptosis and HSD17B4 regulates STAT3 activation, (+)-plakevulin A may induce apoptosis in HL60 cell lines by suppressing STAT3 activation, potentially by binding to HSD17B4. The present findings provide valuable information for the mechanism of its action.

Synthesis and biological evaluation of novel isoxazoloquinone derivatives as potent STAT3-targeting antipsoriasis agents

Psoriasis is a troublesome scaling skin disease with no high-effective medication available by far. Signal transducer and activator of transcription 3 (STAT3) has recently been revealed as a crucial player in the pathogenesis and progression of psoriasis and emerged as an intriguing antipsoriatic drug target. Naturally occurring lapachol and its quinone analogs had been discovered as effective STAT3 inhibitors, however, their antipsoriatic effects are not well investigated. Previously, we have reported a series of isothiazoloquinone lapachol derivatives. Here, the antipsoriastic potentials of these isothiazoloquinones were investigated and, in addition, 35 novel isoxazoloquinone derivatives were prepared and studied for their anti-psoriasis properties. Among them, the most potent antipsoriatic compound B20 determined by in vitro test on HaCaT cells could directly bind to STAT3, reduce STAT3 level and inhibit STAT3 nuclear translocation. In vivo studies showed that topical application of B20 could effectively alleviate IMQ-induced psoriasis in mice with no obvious side effects. In addition, B20 inhibited the production of interleukin 17 (IL-17A), a STAT3-downstream cytokine essential for the progression of psoriasis, both in vitro and in vivo. Thus, isoxazoloquinone B20 is a potent STAT3-targeting antipsoriatic agent worth of further investigation.

Nano co-delivery of doxorubicin and plumbagin achieves synergistic chemotherapy of hepatocellular carcinoma

Doxorubicin (DOX) is a chemotherapy drug used for hepatocellular carcinoma (HCC) treatment, but its effectiveness can be dramatically dampened by cancer cell chemoresistance. Signal transducer and activator of transcription 3 (STAT3) is implicated with drug resistance in a range of cancers (e.g., HCC), and the STAT3 inhibition can reverse the resistance of cancer cells to chemotherapeutic drugs. In the present study, a combination regimen to improve the efficiency of DOX was provided via the STAT3 blockade using plumbagin (PLB). A poly(lactic-co-glycolic acid) decorated by polyethylene glycol and aminoethyl anisamide was produced in the present study with the hope of generating the nanoparticles for co-delivery of DOX and PLB. The resulting co-formulation suppressed the STAT3 activity and achieved the synergistic chemotherapy, which led to tumor inhibition in the mice with subcutaneous DOX-resistant HCC, without causing any toxicity. The present study reveals the synergism of DOX and PLB, and demonstrates a promising combinatorial approach for treating HCC.

Discovering novel derivatives of STAT3 and HDAC inhibitors with anti-tumor activity.

In modern cancer therapy, blockage of more than one target is a standard approach, and there are already many dual-target drugs that can achieve multiple inhibition through a single molecule. Herein, we designed and synthesized a series of novel derivatives with signal transducer and activator of transcription 3 (STAT3) and histone deacetylase (HDAC) inhibitory activity through strategy of combining pharmacophore based on the STAT3 inhibitor E28 and HDAC inhibitor MS-275. Among them, compound 24 (IC50 = 8.22 ± 0.27 μM) showed better anti-tumor activity than the clinical Class I HDAC inhibitor MS-275 (IC50 = 14.65 ± 0.24 μM) in MCF-7 breast cancer cells. Furthermore, the dual inhibition to HDAC and STAT3 of compound 24 was validated by western blot analysis. The study provides new tool compounds for further exploration of STAT3-HDAC pathway inhibitor achieved with a single molecule.

Preclinical study and parallel phase II trial evaluating antisense STAT3 oligonucleotide and checkpoint blockade for advanced pancreatic, non-small cell lung cancer and mismatch repair-deficient colorectal cancer

ObjectiveTo evaluate signal transducer and activator of transcription 3 (STAT3) inhibition we conducted a co-clinical trial testing danvatirsen, a STAT3 antisense oligonucleotide (ASO) and checkpoint inhibition in conjunction with preclinical...

Methoxylated Flavones from Casimiroa edulis La Llave Suppress MMP9 Expression via Inhibition of the JAK/STAT3 Pathway and TNFα-Dependent Pathways.

Matrix metalloproteinase 9 (MMP9), an MMP isozyme, plays a crucial role in tumor progression by degrading basement membranes. It has therefore been proposed that the pharmacological inhibition of MMP9 expression or activity could inhibit tumor metastasis. We previously isolated two novel methoxylated flavones, casedulones A and B, from the leaves and/or roots of Casimiroa edulis La Llave and determined that these casedulones have antitumor activity that acts via the reduction of MMP9. Here, we examined how these casedulones suppress lipopolysaccharide (LPS)-induced MMP9 expression in human monocytic THP-1 cells. The casedulones suppressed the LPS-induced signal transducer and activator of transcription 3 (STAT3) pathway, which participates in MMP9 induction. In addition, AG490 and S3I-201, inhibitors of Janus kinase (JAK) and STAT3, suppressed LPS-mediated MMP9 induction, suggesting that the casedulones suppressed MMP9 induction through the inhibition of JAK/STAT3 pathways. Based on the findings that cycloheximide, an inhibitor of de novo protein synthesis, completely inhibited LPS-mediated MMP9 induction, the role of de novo proteins in MMP9 induction was further investigated. We found that the casedulones inhibited the induction of interleukin-6 (IL-6), a key inflammatory cytokine that participates in STAT3 activation. Moreover, tumor necrosis factor-α (TNFα)-mediated MMP9 induction was significantly suppressed in the presence of the casedulones. Taken together, these findings suggest that casedulones inhibit the IL-6/STAT3 and TNFα pathways, which all involve LPS-mediated MMP9 induction.