Activates STAT3 Phosphorylation Research Articles

ITGA2 as a prognostic factor of glioma promotes GSCs invasion and EMT by activating STAT3 phosphorylation.

Glioma is the most common malignant brain tumor in adults with a high mortality and recurrence rate. Integrin alpha 2 (ITGA2) is involved in cell adhesion, stem cell regulation, angiogenesis and immune cell function. The role of ITGA2 in glioma malignant invasion remains unknown. The function and clinical relevance of ITGA2 were analysed by bioinformatics databases. The expression of ITGA2 in parent cells and GSCs was detected by flow cytometry and immunofluorescence double staining. The role of ITGA2 on the malignant phenotype of GSCs and epithelial-mesenchymal transition (EMT) was identified by stem cell function assays and Western blot. The effect of ITGA2 on glioma progression in vivo was determined by the intracranial orthotopic xenograft model. Immunohistochemistry, Spearman correlation and Kaplan-Meier were used to analyse the relationship of ITGA2 with clinical features and glioma prognosis. Biological analysis showed that ITGA2 might be related to cell invasion and migration. ITGA2, enriched in GSCs and co-expressed with SOX2, promoted the invasion and migration of GSCs by activating STAT3 phosphorylation and enhancing EMT. ITGA2 knockout suppressed the intracranial orthotopic xenograft growth and prolonged the survival of xenograft mice. In addition, the expression level of ITGA2 was significantly correlated to the grade of malignancy, N-cadherin and Ki67. High expression of ITGA2 indicated a worse prognosis of glioma patients. As a biomarker for the prediction of prognosis, ITGA2 promotes the malignant invasion of GSCs by activating STAT3 phosphorylation and enhancing EMT, leading to tumor recurrence and poor prognosis.

Mechanism of M2 type macrophage-derived extracellular vesicles regulating PD-L1 expression via the MISP/IQGAP1 axis in hepatocellular carcinoma immunotherapy resistance

BackgroundHepatocellular carcinoma (HCC) is a prevailing cancer affecting human health. M2 macrophages are essential in mediating immune responses in tumors. This study investigated the action of M2 macrophages in immune escape of HCC. MethodsMitotic spindle positioning (MISP), IQ motif containing GTPase activating protein 1 (IQGAP1) and programmed cell death-1 (PD-L1) levels in primary HCC/tumor-adjacent tissues were determined by Western blot, followed by correlation analysis. M2 macrophage and CD3+CD8+T cell percentages were estimated by flow cytometry. Hep3B and HepG2 cells were treated with M2 macrophage conditioned medium (M2-CM) and M2 macrophage-derived extracellular vesicles (M2-EVs) and/or co-cultured with CD8+T cells, followed by assessment of cell viability and apoptosis. TNF-α and INF-γ levels were measured by ELISA. MISP and IQGAP1 overexpression plasmids were transfected into HCC cells to explore their role in immune escape. The interactions among MISP, IQGAP1, STAT3, and PD-L1 were analyzed by co-immunoprecipitation. The mechanism of M2-EVs in HCC immune escape was verified in nude mice. ResultsMISP/IQGAP1/PD-L1 were upregulated in HCC tissues. MISP negatively-correlated with IQGAP1/PD-L1 and IQGAP1 positively-correlated with PD-L1. M2 macrophages were reduced but CD8+T cells were increased in HCC tissues with high MISP expression. M2-CM or M2-EVs inhibited the killing ability of CD8+T cells, increased HCC cell viability, impeded HCC cell apoptosis, induced CD8+T cell apoptosis, downregulated TNF-α and INF-γ, and upregulated PD-L1. M2-EVs facilitated HCC cell immune escape by potentiating IQGAP1 nuclear translocation and activating STAT3 phosphorylation through MISP downregulation. In vivo experiments further verified the action of M2-EVs through MISP. ConclusionM2-EVs promote HCC cell immune escape by upregulating PD-L1 through the MISP/IQGAP1/STAT3 axis.

Effects and mechanisms of trifluridine alone or in combination with cryptotanshinone in inhibiting malignant biological behavior of gastric cancer

ABSTRACT Background The incidence of gastric cancer (GC) ranks fourth among all malignant tumors worldwide, and the fatality rate ranks second among all malignant tumors. Several Chinese traditional medicines have been used in the treatment of advanced gastric cancer. This study aims to investigate the effect of combinational use of natural product cryptotanshinone (CTS) with anti-cancer drug trifluorothymidine (FTD) in GC. Methods Cell Counting Kit-8 assay was used to detect the inhibitory effect of the combinational or separate use of FTD and CTS on the growth of HGC-27 and AGS GC cells. The combined index of FTD and CTS was calculated using CompuSyn software. To understand the mechanism, we applied flow cytometry to study the cell cycle and cell apoptosis after treatment. We also investigated the amount of FTD incorporated into the DNA by immunofluorescence assay. The expression of relevant proteins was monitored using western blot. Furthermore, the effect of using TAS-102 in combination with CTS was studied in xenograft tumor nude mice model. Results FTD and CTS inhibited the growth of GC cells in a dose-dependent manner, respectively. They both exhibited low to sub-micromolar potency in HGC-27 and AGS cells. The combination of FTD and CTS showed synergistic anticancer effect in HGC-27 cells and AGS cells. Our mechanism studies indicate that FTD could block HGC-27 cells at G2/M phase, while CTS could block HGC-27 cells at G1/G0 phase, while FTD combined with CTS could mainly block HGC-27 cells at G2 phase. FTD in combination with CTS significantly increased the apoptosis of HGC-27 cells. We observed that CTS treatment increased the incorporation of FTD into the DNA HGC-27 cell. FTD treatment activated STAT3 phosphorylation in HGC-27 cells, while CTS treatment down-regulated the concentration of p-STAT3. Interestingly, the combination of CTS and FTD reduced STAT3 phosphorylation induced by FTD. In the in vivo experiments, we observed that the combination of TAS-102 with CTS was significantly more potent than TAS-102 on tumor growth inhibition. Conclusions FTD combined with CTS has a synergistic anti-gastric cancer effect as shown by in vitro and in vivo experiments, and the combined treatment of FTD and CTS will be a promising treatment option for advanced gastric cancer.

PYCR1 promotes the malignant progression of lung cancer through the JAK-STAT3 signaling pathway via PRODH-dependent glutamine synthesize

BackgroundLung cancer is a serious threat to human life. It is of great significance to elucidate the pathogenesis of lung cancer and search for new markers. This study evaluate the clinical value of pyrroline-5-carboxylate reductase 1 (PYCR1) and explore its role and mechanisms in the malignant progression of lung cancer. MethodsPYCR1 expression and its relationship with prognosis were analyzed using a bioinformatics database. Enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry were utilized to examine the expression of PYCR1 in lung cancer tissues and peripheral blood. PYCR1-overexpressing lung cancer cells were constructed, then the cell proliferative, migration, and invasion ability was examined by the MTT and Transwell assays. siRNA against PRODH and STAT3 inhibitor sttatic was used to further elucidate the underlying mechanisms. Luciferase and CHIP assays were carried out for validate the how PYCR1 regulated PD-L1 expression via STAT3. Xenograft experiment was performed to determine the role of PYCR1 in vivo. ResultsDatabase analysis showed that PYCR1 expression was significantly increased in lung cancer tissues, and its high expression predicted poor prognosis. Lung cancer tissue and peripheral blood of patients showed obviously increased PYCR1 expression, and the sensitivity and specificity of serum PYCR1 in the diagnosis of lung cancer were 75.7% and 60%, respectively. PYCR1 overexpression enhanced the proliferative, migration, and invasion abilities of lung cancer cells. Both PRODH silence and stattic effectively attenuated the function of PYCR1. Animal experiment and IHC data indicated that PYCR1 could activated STAT3 phosphorylation and PD-L1, as well as suppressed T cell infiltration in lung cancer. Finally, we also validated that PYCR1 promoted PD-L1 transcription by elevating STAT3 binding to the gene promoter. ConclusionPYCR1 has certain value in the diagnosis and prognosis of lung cancer. Moreover, through regulating JAK-STAT3 signaling pathway, PYCR1 significantly participated in process of lung cancer progression via the metabolism link between proline and glutamine, indicating that PYCR1 might be also a novel therapeutic target.

Aerobic exercise inhibits renal EMT by promoting irisin expression in SHR

To determine the effect of aerobic exercise in different intensities on renal injury and epithelial-mesenchymal transformation (EMT) in the kidney of spontaneously hypertensive rats (SHR) and explore possible mechanisms, we subjected SHR to different levels of 14-week aerobic treadmill training. We tested the effects of aerobic exercise on irisin level, renal function, and EMT modulators in the kidney. We also treated angiotensin II-induced HK-2 cells with irisin and tested the changes in EMT levels. The data showed low and moderate aerobic exercise improved renal function and inhibited EMT through promoting irisin expression in SHR. However, high-intensity exercise training had no effect on renal injury and EMT in SHR but did significantly activate STAT3 phosphorylation in the kidney. These results clarify the mechanisms of exercise in improving hypertension-related renal injury and suggest that irisin might be a therapeutic target for patients with kidney injury.

Neuropilin-2 promotes lineage plasticity and progression to neuroendocrine prostate cancer.

Neuroendocrine prostate cancer (NEPC), a lethal subset of prostate cancer, is characterized by loss of AR signaling and resulting resistance to AR-targeted therapy during neuroendocrine transdifferentiation, for which the molecular mechanisms remain unclear. Here, we report that neuropilin 2 (NRP2) is upregulated in both de novo and therapy-induced NEPC, which induces neuroendocrine markers, neuroendocrine cell morphology, and NEPC cell aggressive behavior. NRP2 silencing restricted NEPC tumor xenograft growth. Mechanistically, NRP2 engages in reciprocal crosstalk with AR, where NRP2 is transcriptionally inhibited by AR, and in turn suppresses AR signaling by downregulating the AR transcriptional program and confers resistance to enzalutamide. Moreover, NRP2 physically interacts with VEGFR2 through the intracellular SEA domain to activate STAT3 phosphorylation and subsequently SOX2, thus driving NEPC differentiation and growth. Collectively, these results characterize NRP2 as a driver of NEPC and suggest NRP2 as a potential therapeutic target in NEPC.

LncRNA PRADX is a Mesenchymal Glioblastoma Biomarker for Cellular Metabolism Targeted Therapy.

Glioblastoma (GBM) is the most common and lethal type of primary malignant central nervous system (CNS) tumor with an extremely poor prognosis, and the mesenchymal subtype of GBM has the worst prognosis. Here, we found that lncRNA PRADX was overexpressed in the mesenchymal GBM and was transcriptionally regulated by RUNX1-CBFβ complex, overexpressed PRADX suppressed BLCAP expression via interacting with EZH2 and catalyzing trimethylation of lysine 27 on histone H3 (H3K27me3). Moreover, we showed that BLCAP interacted with STAT3 and reduced STAT3 phosphorylation, overexpressed PRADX activated STAT3 phosphorylation, and promoted ACSL1 expression via suppressing BLCAP expression, accelerating tumor metabolism. Finally, we determined that combined of ACSL1 and CPT1 inhibitors could reverse the accelerated cellular metabolism and tumor growth induced by PRADX overexpression in vivo and in vitro. Collectively, PRADX/PRC2 complex activated the STAT3 pathway and energy metabolism in relation to mesenchymal GBM progression. Furthermore, our findings provided a novel therapeutic strategy targeting the energy metabolism activity of GBM.

Neuropilin-2 Promotes the Development of Neuroendocrine Prostate Cancer

Neuroendocrine prostate cancer (NEPC), a lethal subset of the disease, is characterized by loss of AR signaling and resulting resistance to AR-targeted therapy during neuroendocrine transdifferentiation, for which the molecular mechanisms remain unclear. Here, we report that neuropilin 2 (NRP2) is upregulated in both de novo and therapy-induced NEPC, which induces neuroendocrine markers, neuroendocrine cell morphology and NEPC cell aggressive behaviors. NRP2 silencing reduced or even eliminated NEPC tumor xenograft growth. Mechanistically, NRP2 engages in reciprocal crosstalk with AR, where NRP2 is a direct transcriptional target inhibited by AR, and in turn, suppresses AR signaling by downregulating the AR transcriptional program and confers resistance to enzalutamide. Moreover, NRP2 physically interacts with VEGFR2 through the intracellular SEA domain to activate STAT3 phosphorylation and subsequently SOX2, thus driving NEPC differentiation and growth. Together these results characterize NRP2 as a driver of NEPC and suggest NRP2 as a potential therapeutic target in NEPC.

Exosomal S100A4 derived from highly metastatic hepatocellular carcinoma cells promotes metastasis by activating STAT3

Intercellular cross-talk plays important roles in cancer progression and metastasis. Yet how these cancer cells interact with each other is still largely unknown. Exosomes released by tumor cells have been proved to be effective cell-to-cell signal mediators. We explored the functional roles of exosomes in metastasis and the potential prognostic values for hepatocellular carcinoma (HCC). Exosomes were extracted from HCC cells of different metastatic potentials. The metastatic effects of exosomes derived from highly metastatic HCC cells (HMH) were evaluated both in vitro and in vivo. Exosomal proteins were identified with iTRAQ mass spectrum and verified in cell lines, xenograft tumor samples, and functional analyses. Exosomes released by HMH significantly enhanced the in vitro invasion and in vivo metastasis of low metastatic HCC cells (LMH). S100 calcium-binding protein A4 (S100A4) was identified as a functional factor in exosomes derived from HMH. S100A4rich exosomes significantly promoted tumor metastasis both in vitro and in vivo compared with S100A4low exosomes or controls. Moreover, exosomal S100A4 could induce expression of osteopontin (OPN), along with other tumor metastasis/stemness-related genes. Exosomal S100A4 activated OPN transcription via STAT3 phosphorylation. HCC patients with high exosomal S100A4 in plasma also had a poorer prognosis. In conclusion, exosomes from HMH could promote the metastatic potential of LMH, and exosomal S100A4 is a key enhancer for HCC metastasis, activating STAT3 phosphorylation and up-regulating OPN expression. This suggested exosomal S100A4 to be a novel prognostic marker and therapeutic target for HCC metastasis.

Hepatoprotective Potency of Chrysophanol 8-O-Glucoside from Rheum palmatum L. against Hepatic Fibrosis via Regulation of the STAT3 Signaling Pathway.

Rhubarb is a well-known herb worldwide and includes approximately 60 species of the Rheum genus. One of the representative plants is Rheum palmatum, which is prescribed as official rhubarb due to its pharmacological potential in the Korean and Chinese pharmacopoeia. In our bioactive screening, we found out that the EtOH extract of R. palmatum inhibited hepatic stellate cell (HSC) activation by transforming growth factor β1 (TGF-β1). Chemical investigation of the EtOH extract led to the isolation of chrysophanol 8-O-glucoside, which was determined by structural analysis using NMR spectroscopic techniques and electrospray ionization mass spectrometry (ESIMS). To elucidate the effects of chrysophanol 8-O-glucoside on HSC activation, activated LX-2 cells were treated for 48 h with chrysophanol 8-O-glucoside, and α-SMA and collagen, HSC activation markers, were measured by comparative quantitative real-time PCR (qPCR) and western blotting analysis. Chrysophanol 8-O-glucoside significantly inhibited the protein and mRNA expression of α-SMA and collagen compared with that in TGF-β1-treated LX-2 cells. Next, the expression of phosphorylated SMAD2 (p-SMAD2) and p-STAT3 was measured and the translocation of p-STAT3 to the nucleus was analyzed by western blotting analysis. The expression of p-SMAD2 and p-STAT3 showed that chrysophanol 8-O-glucoside strongly downregulated STAT3 phosphorylation by inhibiting the nuclear translocation of p-STAT3, which is an important mechanism in HSC activation. Moreover, chrysophanol 8-O-glucoside suppressed the expression of p-p38, not that of p-JNK or p-Erk, which can activate STAT3 phosphorylation and inhibit MMP2 expression, the downstream target of STAT3 signaling. These findings provided experimental evidence concerning the hepatoprotective effects of chrysophanol 8-O-glucoside against liver damage and revealed the molecular basis underlying its anti-fibrotic effects through the blocking of HSC activation.

Dihydroartemisinin Prevents Distant Metastasis of Laryngeal Carcinoma by Inactivating STAT3 in Cancer Stem Cells.

BackgroundAccumulating evidence indicates that cancer stem cells (CSCs) are a minor subpopulation of cancer cells that may be the primary source of cancer invasion, migration, and widespread metastasis.Material/MethodsWe investigated the effects of dihydroartemisinin (DHA) on distant metastasis of laryngeal carcinoma and the relevant mechanism. In vitro, we used the Hep-2 human laryngeal squamous carcinoma cell line (Hep-2 cells) to assemble CSCs, using CD133 as the cell surface marker. Our data demonstrate that the CD133+ subpopulation of Hep-2 cells has greater invasion and migration capabilities than CD133− cells. We also evaluated the effects of DHA, a newly defined STAT3 inhibitor, on the invasion and migration of CD133+ Hep-2 cells under hypoxia and IL-6 stimulation, both of which can activate STAT3 phosphorylation.ResultsCSCs exhibited a significant decrease in the ability of migration and invasion upon the application of DHA, along with simultaneous alterations in related proteins, both in cultured cells and in xenograft tumors. The associated signaling proteins included phosphorylated STAT3 (p-STAT3), matrix metalloproteinase-9 (MMP-9), and E-cadherin, which are closely involved in cancer invasion and metastasis. In vivo, we found that DHA can reduce lung metastasis formation caused by CSCs and prolong survival in mice, and can inhibit STAT3 activation, downregulate MMP-9, and upregulate E-cadherin in lung metastatic tumors.ConclusionsTaken together, our findings indicate that CSCs possess stronger invasive and metastatic capabilities than non-CSCs, and DHA inhibits invasion and prevents metastasis induced by CSCs by inhibiting STAT3 activation.

Inhibition of EGFR-STAT3 attenuates cardiomyopathy in streptozotocin-induced type 1 diabetes.

Emerging evidence implicates elevated activity of STAT3 transcription factor in driving the development and progression of diabetic cardiomyopathy (DCM). We hypothesized that the fibrosis-promoting and hypertrophic actions of STAT3 are linked to the activation by epidermal growth factor receptor (EGFR). We tested this hypothesis by challenging cultured cardiomyocytes to high-concentration glucose and heart tissues of streptozotocin (STZ)-induced type 1 diabetic mice. Our results indicated that, in diabetic mice, the blockade of STAT3 or EGFR using selective inhibitors S3I-201 and erlotinib, respectively, abrogated the increased activating STAT3 phosphorylation and the induction of genes regulating fibrosis and hypertrophy in myocardial tissue. S3I-201 and erlotinib significantly reduced myocardial structural and functional deficits in diabetic mice. In cultured cardiomyocytes, high-concentration glucose induced EGFR-mediated STAT3 phosphorylation. We further showed that blockade of STAT3 or EGFR using selective inhibitors and siRNAs significantly reduced the increased expression of genes known to promote fibrosis and hypertrophy in cardiomyocytes. These results provide novel evidence that the EGFR-STAT3 signaling axis likely plays a crucial role in the development and progression of DCM.

Anterior cleft palate due to Cbfb deficiency and its rescue by folic acid.

ABSTRACTCore binding factor β (Cbfb) is a cofactor of the Runx family of transcription factors. Among these transcription factors, Runx1 is a prerequisite for anterior-specific palatal fusion. It was previously unclear, however, whether Cbfb served as a modulator or as an obligatory factor in the Runx signaling process that regulates palatogenesis. Here, we report that Cbfb is essential and indispensable in mouse anterior palatogenesis. Palatal fusion in Cbfb mutants is disrupted owing to failed disintegration of the fusing epithelium specifically at the anterior portion, as observed in Runx1 mutants. In these mutants, expression of TGFB3 is disrupted in the area of failed palatal fusion, in which phosphorylation of Stat3 is also affected. TGFB3 protein has been shown to rescue palatal fusion in vitro. TGFB3 also activated Stat3 phosphorylation. Strikingly, the anterior cleft palate in Cbfb mutants is further rescued by pharmaceutical application of folic acid, which activates suppressed Stat3 phosphorylation and Tgfb3 expression in vitro. With these findings, we provide the first evidence that Cbfb is a prerequisite for anterior palatogenesis and acts as an obligatory cofactor in the Runx1/Cbfb-Stat3-Tgfb3 signaling axis. Furthermore, the rescue of the mutant cleft palate using folic acid might highlight potential therapeutic targets aimed at Stat3 modification for the prevention and pharmaceutical intervention of cleft palate.

Organic dust induces inflammatory gene expression in lung epithelial cells via ROS-dependent STAT-3 activation.

Exposure to dust in agricultural and animal environments, known as organic dust, is associated with the development of respiratory symptoms and respiratory diseases. Inflammation is a key feature of lung pathologies associated with organic dust exposure, and exposure to organic dust induces the expression of several immune and inflammatory mediators. However, information on transcription factors and cellular and molecular mechanisms controlling the production of immune and inflammatory mediators induced by organic dust is limited. In this study, we have identified STAT-3 as an important transcription factor controlling the induction of expression of immune and inflammatory mediators by poultry dust extracts in airway epithelial cells and in mouse lungs and delineated the cellular pathway for STAT-3 activation. Poultry dust extract activated STAT-3 phosphorylation in Beas2B and normal human bronchial epithelial cells and in mouse lungs. Chemical inhibition and siRNA knockdown of STAT-3 suppressed induction of immune and inflammatory mediator expression. Antioxidants suppressed the increase of STAT-3 phosphorylation induced by poultry dust extract indicating that oxidative stress [elevated reactive oxygen species (ROS) levels] is important for the activation. Chemical inhibition and siRNA knockdown experiments demonstrated that STAT-3 activation is dependent on the activation of nonreceptor tyrosine-protein kinase 2 (TYK2) and epidermal growth factor receptor (EGFR) tyrosine kinases. Our studies show that poultry dust extract controls the induction of immune and inflammatory mediator expression via a cellular pathway involving oxidative stress-mediated STAT-3 activation by TYK2 and EGFR tyrosine kinases.

Neutrophils and IL17A mediate flagellar hook protein FlgE-induced mouse acute lung inflammation.

Bacterial flagellar hook and recombinant flagellar hook protein E (FlgE) were reportedly immunostimulatory in mammalian cells or tissues. Current study focused on the mechanisms underlying FlgE stimulation. In an acute lung injury model induced by intranasal FlgE challenge, neutrophils were the predominant infiltrates in lungs, and depletion of neutrophils with anti-Ly6G antibody attenuated FlgE-induced lung damage. However, the FlgE-induced neutrophils recruitment, neutrophils reactive oxygen species (ROS) generation, and neutrophil extracellular traps (NETs) formation were significantly impaired in Il17a-/- mice compared with those in wild-type (WT) mice. In FlgE-treated lung organoids and isolated neutrophils, the phosphorylation levels of signal transfer and activator of transcription protein 3 (STAT3), which was involved in neutrophils functions, were upregulated, but this upregulation was partly impaired upon IL17A deficiency or by IL6 neutralisation. When neutrophils isolated from WT mice were treated with FlgE, the expression of IL17A/IL17RC was increased, but the activation was blocked by STAT3 inhibitor. The NETs formation in FlgE-treated neutrophils was not affected by the ROS inhibitor or recombinant IL17A alone but partly impaired in the presence of STAT3 pathway inhibition. In conclusion, we propose that the pro-inflammatory activities of FlgE are mediated by activating STAT3 phosphorylation and IL17A/IL17R expression and by promoting a ROS-independent NETs formation.

Cardiotrophin-like Cytokine Increases Macrophage-Foam Cell Transition.

CLCF1 is a neurotrophic and B cell-stimulating factor belonging to the IL-6 family. Mutations in the gene coding for CLCF1 or its secretion partner CRLF1 lead to the development of severe phenotypes, suggesting important nonredundant roles in development, metabolism, and immunity. Although CLCF1 was shown to promote the proliferation of the myeloid cell line M1, its roles on myeloid activation remain underinvestigated. We characterized the effects of CLCF1 on myeloid cells with a focus on monocyte-macrophage and macrophage-foam cell differentiations. CLCF1 injections in mice resulted in a significant increase in CD11b+ circulating cells, including proinflammatory monocytes. Furthermore, CLCF1 activated STAT3 phosphorylation in bone marrow CD11b+ cells and in bone marrow-derived macrophages (BMDM). BMDM stimulated with CLCF1 produced a large array of proinflammatory factors comprising IL-6, IL-9, G-CSF, GM-CSF, IL-1β, IL-12, CCL5, and CX3CL1. The pattern of cytokines and chemokines released by CLCF1-treated BMDM led us to investigate the role of CLCF1 in foam cell formation. When pretreated with CLCF1, BMDM presented a marked SR-A1 upregulation, an increase in acetylated-low-density lipoprotein uptake, and an elevated triglyceride accumulation. CLCF1-induced SR-A1 upregulation, triglyceride accumulation, and acetylated-low-density lipoprotein uptake could be prevented using ruxolitinib, a JAK inhibitor, indicating that the effects of the cytokine on myeloid cells result from activation of the canonical JAK/STAT signaling pathway. Our data reveal novel biological roles for CLCF1 in the control of myeloid function and identify this cytokine as a strong inducer of macrophage-foam cell transition, thus bringing forward a new potential therapeutic target for atherosclerosis.

Therapeutic Ablation of Gain-of-Function Mutant p53 in Colorectal Cancer Inhibits Stat3-Mediated Tumor Growth and Invasion

Over half of colorectal cancers (CRCs) harbor TP53 missense mutations (mutp53). We show that the most common mutp53 allele R248Q (p53Q) exerts gain of function (GOF) and creates tumor dependence in mouse CRC models. mutp53 protein binds Stat3 and enhances activating Stat3 phosphorylation by displacing the phosphatase SHP2. Ablation of the p53Q allele suppressed Jak2/Stat3 signaling, growth, and invasiveness of established, mutp53-driven tumors. Treating tumor-bearing mice with an HSP90 inhibitor suppressed mutp53 levels and tumor growth. Importantly, human CRCs with stabilized mutp53 exhibit enhanced Jak2/Stat3 signaling and are associated with poorer patient survival. Cancers with TP53R248Q/W are associated with a higher patient death risk than are those having nonR248 mutp53. These findings identify GOF mutp53 as a therapeutic target in CRC.

Suppression of Elp2 prevents renal fibrosis and inflammation induced by unilateral ureter obstruction (UUO) via inactivating Stat3-regulated TGF-β1 and NF-κB pathways

Renal fibrosis and inflammation are common underlying processes of progressive kidney diseases. Elongator protein 2 (Elp2), identical to signal transducer and activator of transcription-3 (STAT-3)-interacting protein-1 (Stip1), is a component of the Elongator complex that regulates RNA polymerase II. Elp2 regulates STAT-3 activation to control various cellular processes. The mechanisms of Elp2 prevention in renal interstitial fibrosis and inflammation remain unknown. In the study, Elp2 transgenic knockout (KO) and wild type (WT) mice were employed to investigate the effects of Elp2 on renal fibrosis and inflammation development after unilateral ureter obstruction (UUO) surgery. The results indicted that Elp2 was significantly expressed in renal tissues of WT/UUO mice. Elp2-KO mice exhibited attenuated histological changes of kidney, as well as collagen and fibrosis accumulation. Lower expressions of transforming growth factor (TGF)-β1, α-smooth muscle actin (α-SMA), fibronectin, vimentin, and phospho-Smad2/3 were observed in kidney of Elp2-KO mice than that of WT mice after UUO. Elp2-KO mice showed less inflammation, as evidenced by the decrease of circulating or renal pro-inflammatory cytokines, as well as the reduction of phospho-nuclear factor (NF)-κB. Additionally, Elp2-KO apparently led to a decrease in phospho-STAT3 in kidney of UUO mice. In vitro, we found that TGF-β1- and LPS-induced fibrosis and inflammation were abrogated by Elp2 knockdown, which were intriguingly abolished by activating STAT3 phosphorylation using its activator of colivelin (Col). Together, our findings supplied that Elp2 might be a potential therapeutic target to prevent the progression of renal fibrosis and inflammation.

Interleukin 6 induces M2 macrophage differentiation by STAT3 activation that correlates with gastric cancer progression.

Interleukin 6 (IL-6) was abundant in the tumor microenvironment and played potential roles in tumor progression. In our study, the expression of IL-6 in tumor tissues from 36 gastric cancer (GC) patients was significantly higher than in non-tumor tissues. Moreover, the number of CD163+CD206+ M2 macrophages that infiltrated in tumor tissues was significantly greater than those infiltrated in non-tumor tissues. The frequencies of M2 macrophages were positively correlated with the IL-6 expression in GC tumors. We also found that IL-6 could induce normal macrophages to differentiate into M2 macrophages with higher IL-10 and TGF-β expression, and lower IL-12 expression, via activating STAT3 phosphorylation. Accordingly, knocking down STAT3 using small interfering RNA decreased the expression of M2 macrophages-related cytokines (IL-10 and TGF-β). Furthermore, supernatants from IL-6-induced M2 macrophages promote GC cell proliferation and migration. Moreover, IL-6 production and CD163+CD206+ M2 macrophage infiltration in tumors were associated with disease progression and reduced GC patient survival. In conclusion, our data indicate that IL-6 induces M2 macrophage differentiation (IL-10highTGF-βhighIL-12 p35low ) by activating STAT3 phosphorylation, and the IL-6-induced M2 macrophages exert a pro-tumor function by promoting GC cell proliferation and migration.

Increased tumor-infiltrating CD45RA\u2212CCR7\u2212 regulatory T-cell subset with immunosuppressive properties foster gastric cancer progress

Regulatory T cells (Tregs) are major components of tumor-infiltrating immune cells with potent immunosuppressive properties in gastric cancer (GC) microenvironment. However, different subsets of the Tregs and their relevance to GC are unknown. Here, we found that patients with GC showed a significantly higher Tregs infiltration in tumors, and CD45RA−CCR7− Treg subset constituted most tumor-infiltrating Tregs. Tumor-infiltrating CD45RA−CCR7− Treg subset with an effector/memory phenotype accumulated in tumors and expressed low level of HLA-DR. Gastric tumor-derived TNF-α induced CD45RA−CCR7− Treg subset with similar phenotype to their status in tumors and inhibited their HLA-DR expression via activating STAT3 phosphorylation. These tumor-associated CD45RA−CCR7− Treg subset exerted superior immunosuppressive properties to effectively suppress CD8+ T cells’ anti-tumor function including CD8+ T-cell IFN-γ and granzyme B (GrB) production as well as CD8+ T-cell proliferation in vitro, and also contributed to the growth and progression of human gastric tumors in vivo, via IL-10 secretion and cell–cell contact mechanisms. Moreover, increased tumor-infiltrating CD45RA−CCR7− Treg subset as well as higher intratumoral CD45RA−CCR7− Treg/CD8+ T-cell ratio was associated with advanced disease progression and reduced GC patient survival. This study therefore identifies a novel immunosuppressive pathway involving CD45RA−CCR7− Treg subset development within the GC microenvironment. Efforts to inhibit this pathway may therefore prove a valuable strategy to prevent, and to treat this immune suppressive of GC.