Levels Of Signal Transducer And Activator Of Transcription 3 Research Articles

Down-regulation of STAT3 enhanced chemokine expression and neutrophil recruitment in biliary atresia.

Biliary atresia (BA) is an immune-related disorder and signal transducer and activator of transcription 3 (STAT3) is a key signalling molecule in inflammation. The present study was designed to clarify the function of STAT3 in BA. STAT3 expression was examined in patients and a mouse BA model in which STAT3 levels were further altered with a specific inhibitor or activator. Neutrophil accumulation and the levels of the neutrophil chemoattractants (C–X–C motif) ligand 1 (CXCL1) and IL-8 were determined. The effects of STAT3 inhibition on IL-8 expression were examined in human biliary epithelial cell (BEC) cultures. Functional changes in liver STAT3+ neutrophils in the mouse model were analysed with 10× single cell RNA-seq methods. Results showed STAT3 and p-STAT3 expression was reduced in BA liver tissue compared with control samples. Administration of a STAT3 inhibitor increased jaundice and mortality and reduced body weight in BA mice. In contrast, the STAT3 activator ameliorated BA symptoms. Extensive neutrophil accumulation together with CXCL1 up-regulation, both of which were suppressed by an anti-CXCL1 antibody, were observed in the STAT3 inhibitor-treated group. Recombinant IL-8 administration increased disease severity in BA mice, and the STAT3 activator had the reverse effect. Inhibiting STAT3 increased apoptosis of human BECs together with up-regulated IL-8 expression. RNA-seq analysis revealed reduced the numbers of STAT3 expressing neutrophil in BA which was accompanied by marked enhanced interferon-related antiviral activities. In conclusion, STAT3 reduction, enhanced IL-8 and CXCL1 expression and promoted the accumulation of interferon-responsive neutrophils resulting in BEC damage in BA.

Fangchinoline diminishes STAT3 activation by stimulating oxidative stress and targeting SHP-1 protein in multiple myeloma model

IntroductionThe development of cancer generally occurs as a result of various deregulated molecular mechanisms affecting the genes that can control normal cellular growth. Signal transducer and activator of transcription 3 (STAT3) pathway, once aberrantly activated can promote carcinogenesis by regulating the transcription of a number of oncogenic genes. ObjectivesHere, we evaluated the impact of fangchinoline (FCN) to attenuate tumor growth and survival through modulation of oncogenic STAT3 signaling pathway using diverse tumor cell lines and a xenograft mouse model. MethodsTo evaluate the action of FCN on STAT3 cascade, protein levels were analyzed by Western blot analysis and electrophoretic mobility shift assay (EMSA). Translocation of STAT3 was detected by immunocytochemistry. Thereafter, FCN-induced ROS was measured by GSH/GSSG assay and H2DCF-DA. FCN-induced apoptosis was analyzed using Western blot analysis and flow cytometry for various assays. Finally, anti-cancer effects of FCN in vivo was evaluated in a myeloma model. ResultsWe noted that FCN abrogated protein expression levels of STAT3 and upstream signals (JAK1/2 and Src). In addition, FCN also attenuated DNA binding ability of STAT3 and its translocation into the nucleus. It altered the levels of upstream signaling proteins, increased SHP-1 levels, and induced substantial apoptosis in U266 cells. FCN also promoted an increased production of reactive oxygen species (ROS) and altered GSSG/GSH ratio in tumor cells. Moreover, FCN effectively abrogated tumor progression and STAT3 activation in a preclinical myeloma model. ConclusionOverall, this study suggests that FCN may have a tremendous potential to alter abnormal STAT3 activation and induce cell death in malignant cells along with causing the suppression of pathogenesis and growth of cancer through a pro-oxidant dependent molecular mechanism.

STAT3 promotes peritoneal metastasis of gastric cancer by enhancing mesothelial-mesenchymal transition.

Signal transducer and activator of transcription 3 (STAT3) is a widely-reported oncogene in many human cancers, but its role in the peritoneal metastasis of gastric cancer (GC) has yet to be studied. The expression level of STAT3 in GC patient tissues was assessed. Stable shRNA knockdown (KD) of STAT3 was established in GCcell line AGS, followed by examination of its effect on AGC cell viability and proliferation, xenograft tumor growth, metastatic potential, mesothelial-to-mesenchymal transition (MMT)-related properties and peritoneal metastasis in a mouse model. The specific STAT3 inhibitor BP1-102 was also employed to verify findings from STAT3 KD experiments. Expression of activated STAT3 was upregulated in GC patient tumor tissues, and further elevated among patients diagnosed with peritoneal metastasis. STAT3 deactivation suppressed viability and proliferation of GCcells in vitro, as well as GC tumorigenesis in vivo. Furthermore, the metastatic properties and production of MMT-inducing factors of GC cells in vitro were also dependent on STAT3 activation. Importantly, STAT3 KD significantly compromised peritoneal metastasis of GC in vivo. STAT3 activation contributes to peritoneal metastasis of GC by promoting MMT, warranting further investigation to explore its potential for GC treatment, in particular among peritoneal metastasis patients.

The expression and clinical significance of signal transducer and activator of transcription 3, tumor necrosis factor α induced protein 8-like 2, and runt-related transcription factor 1 in breast cancer patients.

This study explored the expression and clinical significance of signal transducer and activator of transcription 3 (STAT3), tumor necrosis factor α induced protein 8-like 2 (TIPE2), and runt-related transcription factor 1 (RUNX1) in breast cancer tissue. From October 2014 to October 2017, 68 breast cancer patients (68 breast cancer tissue specimens) who underwent a radical mastectomy in our hospital were set as the observation group and the corresponding normal tissue 3 cm away from the cancer tissue was selected as the control group. The expression levels of STAT3, TIPE2, and RUNX1 in the two groups were compared via immunohistochemical staining. Multiple logistic regression was then used to analyze the related risk factors affecting the 2-year prognosis of breast cancer patients. The receiver operating characteristic (ROC) curve was then plotted and the area under the ROC curve was calculated. The predictive values of STAT3, TIPE2, and RUNX1, and the predictive value of the three transcription factors combined on the 2-year prognostic survival of breast cancer patients were determined. (I) In the observation group, the positive expression of STAT3 and the negative expression of TIPE2 and RUNX1 were significantly higher than those in the control group (P<0.05). (II) Of the 68 patients, 51 survived within 2 years and 17 patients died. Positive STAT3 expression, negative TIPE2 expression, negative RUNX1 expression, poor histological differentiation, TNM stage III-IV, and distant metastasis were all identified as factors that can affect the 2-year prognosis of breast cancer patients (P<0.05). (III) The ROC curve analysis examining the 2-year prognostic survival of breast cancer patients showed that the area under the curve achieved the largest value when the predictive values of STAT3, TIPE2, RUNX1 were combined. The levels of STAT3, TIPE2, and RUNX1 expression in breast cancer tissues were significantly different from that in adjacent normal tissues. This suggested that the combined detection of STAT3, TIPE2, and RUNX1 may improve the rate of early breast cancer diagnosis. Furthermore, STAT3, TIPE2, and RUNX1 may be useful in evaluating the prognosis of the patients with breast cancer.

Activation of Interferon Signaling in Chronic Lymphocytic Leukemia Cells Contributes to Apoptosis Resistance via a JAK-Src/STAT3/Mcl-1 Signaling Pathway

Besides their antiviral and immunomodulatory functions, type I (α/β) and II (γ) interferons (IFNs) exhibit either beneficial or detrimental effects on tumor progression. Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of abnormal CD5+ B lymphocytes that escape death. Drug resistance and disease relapse still occur in CLL. The triggering of IFN receptors is believed to be involved in the survival of CLL cells, but the underlying molecular mechanisms are not yet characterized. We show here that both type I and II IFNs promote the survival of primary CLL cells by counteracting the mitochondrial (intrinsic) apoptosis pathway. The survival process was associated with the upregulation of signal transducer and activator of transcription-3 (STAT3) and its target anti-apoptotic Mcl-1. Furthermore, the blockade of the STAT3/Mcl-1 pathway by pharmacological inhibitors against STAT3, TYK2 (for type I IFN) or JAK2 (for type II IFN) markedly reduced IFN-mediated CLL cell survival. Similarly, the selective Src family kinase inhibitor PP2 notably blocked IFN-mediated CLL cell survival by downregulating the protein levels of STAT3 and Mcl-1. Our work reveals a novel mechanism of resistance to apoptosis promoted by IFNs in CLL cells, whereby JAKs (TYK2, JAK2) and Src kinases activate in concert a STAT3/Mcl-1 signaling pathway. In view of current clinical developments of potent STAT3 and Mcl-1 inhibitors, a combination of conventional treatments with these inhibitors might thus constitute a new therapeutic strategy in CLL.

MicroRNA-935-modified bone marrow mesenchymal stem cells-derived exosomes enhance osteoblast proliferation and differentiation in osteoporotic rats

AimsThe involvement of several microRNAs (miRNAs) in osteogenic differentiation has been indicated recently. Also, exosomes, derived from different cells, could shuttle specific miRNAs to other cell systems. Nevertheless, the effect and mechanism of microRNA-935 (miR-935)-containing exosomes in osteoblasts remain basically unclear. The current work was set to inspect the relevance of bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (BMSC-exo) carrying miR-935 to osteoporotic rats. MethodsThe extracted BMSCs and purchased osteoblasts were cultured, followed by exosome isolation and identification. After cell grouping, osteoblasts were co-cultured with BMSCs. CCK-8, alizarin red staining as well as ALP staining were performed to detect osteoblast proliferation and activity. The binding connection between miR-935 and signal transducer and activator of transcription 1 (STAT1) was measured by dual-luciferase reporter gene assays. The expression profiles of miR-935, STAT1 and osteoblast-related proteins were assessed by RT-qPCR and Western blot. A rat model with osteoporosis was induced, and the BMD, BV/TV, Tb.N, Tb.Th and Tb.Sp values in rat bone tissues were observed by Micro-CT. ResultsBMSC-exo inhibited STAT1 levels by the delivery of miR-935 into osteoblasts, while STAT1 silencing promoted ALP activity in osteoblasts and mineralized nodules. STAT1 was identified as a target gene of miR-935. Moreover, in vivo experiments showed that in ovariectomized rats, silencing of miR-935 significantly reduced BMD, BV/TV, Tb.N, Tb.Th and increased Tb.Sp. ConclusionBMSC-exo carry miR-935 to promote osteoblast proliferation and differentiation through targeting STAT1.

Increased Melanoma-Associated Antigen C2 Expression Affords Resistance to Apoptotic Deathin Suspension-Cultured Tumor Cells.

PurposeMelanoma-associated antigen C2 (MAGEC2) is an oncogene associated with various types of cancers. However, the biological function of MAGEC2 in circulating tumor cells remains unclear. In this study, we investigated the role of MAGEC2 using adapted suspension cells (ASCs), which were previously developed to study circulating tumor cells (CTCs).MethodsDifferential gene expression in adherent cells (ADs) and ASCs was examined using RNA-seq analysis. MAGEC2 expression was assessed using reverse transcription quantitative polymerase chain reaction (RT-qPCR), immunoblotting, and ChIP-seq analysis. Depletion of MAGEC2 expression was performed using siRNA. MAGEC2-depleted ADs and ASCs were used to investigate changes in the proliferation rate and cell cycle. Then, the protein levels of signal transducer and activator of transcription 3 (STAT3), phosphorylated STAT3, and downstream of STAT3 were measured using control and MAGEC2-depleted ADs and ASCs. In ASCs, the direct effect of active STAT3 inhibition with Stattic, a STAT3 inhibitor, was assessed in terms of proliferation and apoptosis. Finally, an Annexin V/7-AAD assay was performed to determine the percentage of apoptotic cells in the Stattic-treated cells.ResultsMAGEC2 was highly expressed in ASCs when compared with ADs. Depletion of MAGEC2 reduced the proliferation rate and viability of ASCs. To elucidate the underlying mechanism, the level of STAT3 was examined owing to its oncogenic properties. Tyrosine-phosphorylated active STAT3 was highly expressed in ASCs and decreased in MAGEC2-depleted ASCs. Furthermore, on treating ASCs with Stattic, an active STAT3 inhibitor, the cells were markedly sensitive to intrinsic pathway-mediated apoptosis.ConclusionsHigh MAGEC2 expression may play an important role in the survival of ASCs by maintaining the expression of activated STAT3 to prevent apoptotic cell death.

Suppression of Esophageal Cancer Stem-like Cells by SNX-2112 Is Enhanced by STAT3 Silencing.

Many studies have demonstrated that cancer stem cells (CSCs) or tumor-initiating cells (TICs) are responsible for tumor cell proliferation, chemotherapy resistance, metastasis, and relapse in various cancers. We, and others, have previously shown that the signal transducer and activator of transcription 3 (STAT3) signaling pathway is responsible for CSCs and TICs growth. Recent reports have indicated that the heat shock protein 90 (Hsp90) is also essential for the survival of CSCs and TICs. SNX-2112 is an Hsp90 inhibitor. However, it remains unclear whether proliferation of esophageal cancer stem-like cells (ECSLCs) is suppressed by SNX-2112 with knockdown of STAT3 (shSTAT3). Here, we explored the association between SNX-2112 with shSTAT3 and the suppression of ECSLCs growth. We found that the expression level of both STAT3 and p-STAT3 was higher in clinical esophageal cancer tissue than in the adjacent normal tissue, using western blot and qPCR analysis. Furthermore, differential expression analysis demonstrated that STAT3 was overexpressed in clinical specimens. We demonstrated that SNX-2112 inhibited cancer cell proliferation, decreased ABCB1 and ABCG2 gene expression levels and reduced the colony formation capacity of ECSLCs, which was enhanced by STAT3 silencing. Flow cytometry analysis revealed that the combination of SNX-2112 and shSTAT3 significantly induced apoptosis and cell cycle arrest at G2/M phase in ECSLCs. Levels of proliferation pathway proteins, including p38, c-Jun N-terminal kinase (JNK), and extracellular signal–regulated kinase (ERK) which were also client proteins of Hsp90, were also reduced. In addition, SNX-2112 with shSTAT3 inhibited the proliferation of ECSLCs in vivo. Finally, STAT3 overexpression eliminated the apoptotic and antiproliferative effects of SNX-2112 on ECSLCs. Hence, these results provide a rationale for the therapeutic potential of the combination of SNX-2112 with shSTAT3 in esophageal cancer, and may indicate new targets for clinical intervention in human cancer.

Palmitoyl piperidinopiperidine, a novel derivative of 10‑hydroxy‑2‑decenoic acid, as a potent and selective anticancer agent against human colon carcinoma cell lines.

The present study, to the best of our knowledge, is the first systematic study of the inhibitory effects of palmitoyl piperidinopiperidine (PPI; Japan Patent no.5597427), on colon carcinogenesis. PPI exhibited marked growth inhibitory activity in several human colon carcinoma cell lines, with IC50 values of approximately 0.5‑2.2µM. Insilico docking analysis indicated that PPI could bind to the SH2 domain of signal transducer and activator of transcription 3 (STAT3). PPI markedly inhibited the transcriptional activity of the SW837 cell line. Flowcytometric analysis demonstrated that PPI induced an increase in the number of cells in the G1 phase of the cell cycle, and induced sub‑G1 fractions of cells at a higher concentration level of PPI. In the HT29 and SW837 cells, western blot analyses exhibited that in whole cell lysates, PPI induced a marked decrease in the expression levels of p‑STAT3, but not in the levels of STAT3 in these cells. PPI also induced a marked decrease in the expression levels of both STAT3 and p‑STAT3 in the chromatin fraction. In addition, PPI affected the protein expression levels of cyclin D1, p53, Bcl‑2, Bcl‑xL and vascular endothelial growth factor (VEGF). In the HT29 cells, PPI induced a marked and dose‑dependent increase in the expression levels of Bax, cleaved caspase‑3, cleaved caspase‑7, cleaved caspase‑8, cleaved caspase‑9 and cleaved poly (ADP‑ribose) polymerase (PARP). In animal model systems, PPI inhibited the growth of implanted carcinoma cells, and also induced a significant decrease in the multiplicity of colonic aberrant crypt foci. In addition, a marked and dose‑dependent inhibition of angiogenesis of the chick chorioallantoic membrane was observed. As regards the possible molecular mechanisms, it is suggested that the inhibition of STAT3 by PPI may affect the function of molecules that are related to apoptosis, angiogenesis and cell cycle progression, eventually contributing to the PPI‑induced growth inhibitory effects.

The sesquiterpene lactone eupatolide induces apoptosis in non-small cell lung cancer cells by suppressing STAT3 signaling

We aimed to evaluate the role of a natural sesquiterpene lactone, eupatolide, in non-small-cell lung cancer (NSCLC) and further explore its underlying mechanism on regulating the activation of signal transducer and activator of transcription 3 (STAT3), which is thought to have carcinogenic function in a variety of malignancies including lung cancer. Cell survival was measured by Cell Counting Kit-8 assay. in vivo experiments were performed by inoculating NSCLC cells into nude mice. Western blot and qRT-PCR were applied to detect the activation level of STAT3 and the mRNA levels of anti-apoptotic markers. The cell apoptosis was measured by Annexin V-FITC/PI Apoptosis Detection Kit. Our results showed that eupatolide suppressed the survival of NSCLC cells in a dose and time dependent manner. Furthermore, eupatolide increased the anti-tumor activity of the chemotherapeutic drugs cisplatin and 5-Fluoracil (5-FU). The xenograft study revealed that eupatolide suppressed tumor growth of NSCLC cells in vivo. Furthermore, eupatolide induced apoptosis by suppressing the activation of STAT3 in NSCLC cells. Sustained activation or knockdown of STAT3 suppressed and enhanced the activity of eupatolide, respectively. This paper is the first to report that eupatolide could effectively inhibit NSCLC progression, suggesting that eupatolide might be utilized as a novel STAT3 inhibitor for treating NSCLC.

RNF180 mediates STAT3 activity by regulating the expression of RhoC via the proteasomal pathway in gastric cancer cells

Ring finger protein 180 (RNF180) is an important member of the E3 ubiquitin ligase family. As a tumor suppressor gene, RNF180 is significantly associated with the prognosis of patients with gastric cancer (GC) and can inhibit the proliferation, invasion, and migration of GC cells. Signal transducer and activator of transcription 3 (STAT3) are considered one of the most common oncogenes in human cancers with a key role in GC progression. In this study, we explored the molecular signaling pathways by which RNF180 could potentially regulate STAT3 through transcriptomics and proteomics experiments. Here, we found RNF180 overexpression could suppress STAT3 phosphorylation in GC cells. Ubiquitin label-free experiments showed that the ubiquitination level of Ras homolog gene family member C (RhoC) is significantly increased in GC cells transfected with an RNF180 expression vector (RNF180-GFP vector) compared with cells transfected with an empty vector (vehicle vector). We subsequently demonstrated that RNF180 could directly combine with RhoC and promote the ubiquitination and degradation of RhoC protein in GC cells. The phosphorylation level of STAT3 significantly decreased in GC cells after RhoC knockdown using small hairpin RNA (shRNA). Together, these results reveal RNF180 could inhibit GC progression by reducing the phosphorylation of STAT3 via the ubiquitination and degradation of RhoC protein in GC cells. Thus, the protein may be considered a novel therapeutic target for patients with GC.

Effect of acupuncture and moxibustion on expression of signal transducers and activators of transcription 3 and hypoxia-inducible factor 1α in colon mucosa in ulcerative colitis mice

To investigate the effect of acupuncture or moxibustion of "Zusanli" (ST36) and "Guanyuan" (CV4) on expression of signal transducers and activators of transcription 3 (STAT3) and hypoxia-inducible factor 1α (HIF-1α) in colonic tissue in ulcerative colitis (UC) mice. Thirty-two male Kunming mice were randomly divided into control, model, acupuncture and moxibustion groups (n=8 in each group). The UC model was induced by free drinking of 3% Dextran Sodium Sulfate for 7 days. Acupuncture or moxibustion was applied to ST36 or CV4 for 15 min, once daily for 5 days. The severity of UC was monitored using the disease activity index (DAI) which includes evaluation of weight loss, stool consistency, and presence of fecal blood. Histopathological changes of the colon mucosa were observed by H.E. staining. Immunohistochemistry and Western blot were employed to detect the expression of STAT3 and HIF-1α proteins in the colon mucosa tissue. After modeling, the DAI, immunoactivity and expression of STAT3 and HIF-1α in the colonic tissue were significantly increased in the model group relevant to the control group (P<0.01,P<0.05). Compared with the model group, the levels of DAI, STAT3 and HIF-1α considerably decreased in both acupuncture and moxibustion groups (P<0.05), and without significant differences between the two intervention groups in the levels of DAI, STAT3 and HIF-1α after the intervention (P>0.05). H.E. staining of the colonic tissue showed damage and infiltration of inflammatory cells in the model group, and reduction of the submucosal edema and infiltrated inflammatory cells in the acupuncture and moxibustion groups. Both acupuncture and moxibustion can improve UC in UC mice, which may be associated with its effects in down-regulating the expression of colonic STAT3 and HIF-1α proteins.

Dual PLK1 and STAT3 inhibition promotes glioblastoma cells apoptosis through MYC

Glioblastoma (GBM) is the deadliest primary brain tumor that is highly resistant to current treatments. Polo-like kinase 1 (PLK1) and signal transducer and activator of transcription 3 (STAT3) are highly expressed in gliomas, especially GBM. Previous studies have shown reciprocal activation between PLK1 and STAT3 and that they regulate the same pools of MYC downstream. We have demonstrated that PLK1 and STAT3 levels are elevated in gliomas compared with those in normal brain tissues, and high expression of both PLK1 and STAT3 is associated with poor prognosis in TCGA. Moreover, there was direct or indirect reciprocal regulation between PLK1 and STAT3. Furthermore, we found that PLK1 and STAT3 can regulate the same pools of MYC downstream. Compared to monotherapy, combined treatment of glioma cells with PLK1 and STAT3 inhibitors, BI2536 and Stattic, respectively, showed lower expression of MYC, synergistic induction of cell invasion and apoptosis in vitro, and tumor inhibition in xenografts. PLK1 and STAT3 were able to directly regulate the expression of MYC and induce apoptosis of glioma cells through the regulation of MYC. These findings may help develop a therapeutic strategy for dual inhibition of PLK1 and STAT3 against the tumorigenesis of glioma.

Nrf2 and STAT3 Alleviates Ferroptosis-Mediated IIR-ALI by Regulating SLC7A11.

Acute lung injury (ALI) has gained increased attention in the field of critical illness research and is associated with a fatality rate of approximately 50%. Nuclear factor erythroid 2-related factor2 (Nrf2) is a key regulator of intracellular oxidation homeostasis and also functions as an antioxidant. It has been reported that Nrf2 associated antioxidant stress is closely related to ferroptosis inhibition. Signal transducer and activator of transcription 3 (STAT3) is activated into phosphorylated STAT3 (pSTAT3) in response to tissue damage and serves as a warning signal to enhance the inflammatory response. In this study, an intestinal ischemia/reperfusion-induced acute lung injury (IIR-ALI) model was established in C57BL/6 mice to investigate the role of Nrf2 in regulating IIR-ALI-associated ferroptosis. Compared with those in the IIR-ALI group, the injection of Fe (15 mg/kg) or ferrostatin-1 (5 mg/kg) (ferroptosis promoter and inhibitor, respectively) via the tail vein could aggravate or alleviate lung injury and pulmonary edema, respectively. Nrf2 was increased in IIR-ALI and promoted the phosphorylation of STAT3 to amplify downstream signals. An in vitro oxygen-glucose deprivation and reoxygenation (OGD-R) model was established in MLE12 cells to imitate the ischemia/reperfusion condition. The cells were transfected with lentiviruses to increase or downregulate the levels of STAT3. We found that Nrf2 and STAT3 played key roles in ferroptosis by regulating SLC7A11, which improved the pathological processes associated with ALI.

A Positive Feedback Loop of lncRNA DSCR8/miR-98-5p/STAT3/HIF-1α Plays a Role in the Progression of Ovarian Cancer.

BackgroundAccumulating studies have revealed that long non-coding RNA (lncRNA) and microRNA (miRNA) contribute to ovarian cancer (OC). DSCR8 has been found to mediate hepatocellular carcinoma development, while its role in OC remains to be explored.MethodsIn this study, lncRNA DSCR8 and miR-98-5p expressions in OC tissues and adjacent non-cancer tissues were determined by reverse transcriptase polymerase chain reaction (RT-PCR). Besides, gain-of-function or loss-of-function assays of DSCR8 and miR-98-5p were conducted on OC cell lines SKOV-3 and A2780. Cell proliferation was detected with Cell Counting Kit (CCK)8 and colony formation assay, and western blot was used to test the apoptotic levels of OC cells. Transwell assay was conducted to examine cell invasion, and the epithelial–mesenchymal transition (EMT) of OC cells was tested by western blot. Moreover, luciferase activity assay and RNA immunoprecipitation (RIP) assay were conducted to verify the relationships between DSCR8 and miR-98-5p, miR-98-5p, and signal transducer and activator of transcription 3 (STAT3).ResultsDSCR8 was remarkedly increased in OC tissues and associated with poorer survival of OC patients. Overexpressing DSCR8 promoted cell proliferation, invasion, and EMT but inhibited apoptosis. On the other hand, miR-98-5p was downregulated in OC tissues and relieved the progression of OC. Moreover, overexpressed DSCR8 increased the levels of STAT3 and hypoxia inducible factor 1 alpha (HIF-1α) and dampened the functions of miR-98-5p on OC. Pharmaceutical intervention of STAT3 and HIF-1α significantly altered the expressions of DSCR8 and miR-98-5p.ConclusionThe present results suggested a positive feedback loop of lncRNA DSCR8/miR-98-5p/STAT3/HIF-α axis in the progression of OC.

Abstract 4151: STAT3 regulates chemo-resistance and cancer stemness in hepatocellular carcinoma

Abstract Hepatocellular carcinoma (HCC) is a major global health problem and its treatment outcomes are limited by therapeutic resistance. Cancer stem cells are the roots of tumor growth, recurrence, metastasis and treatment resistance. Signal transducer and activator of transcription 3 (STAT3) is a transcription factor well known to promote carcinogenesis in a number of tumors. The present study aims to investigate the role of STAT3 in HCC. Total STAT3 levels were examined by qRT-PCR in patients with primary HCC who underwent curative partial hepatectomy. Elevated STAT3 levels were significantly associated with poor recurrence-free survival and overall survival of HCC patients (log-rank test, P = 0.019 and 0.008, respectively). Immunohistochemistry (IHC) was performed to determine the activation status of STAT3 in HCC. Phosphorylated (p)-Y705 and p-S727 staining was detected in HCC tissues, albeit with varying patterns of expression. To investigate the efficacy of STAT3-targeted therapeutics in HCC, napabucasin, a cancer stemness inhibitor targeting STAT3-driven gene transcription, and the specific small interfering RNA (siRNA) were examined in HCC cell lines Hep3B, HepG2 and Huh7. Both napabucasin and siRNA prominently downregulated RNA and protein levels of total STAT3 and p-STAT3 of HCC cells. Napabucasin reduced viability, induced death, hindered migration, impaired colony and spheroid formation efficiency of HCC cells, as well as lowered expression levels of the cancer stem cell markers granulin-epithelin precursor (GEP) and CD133 in whole genome RNA sequencing analysis. Notably, napabucasin combined with 5-fluorouracil (5-FU) synergistically inhibited cell proliferation and induced apoptosis, suggesting its potential in sensitizing HCC cells to chemotherapeutic agents. In addition, napabucasin diminished the colony and spheroid formation abilities of chemo-resistant HCC cells (acquired resistance to 5-FU with over 10-fold increase) to a similar extent as their parental counterparts, indicating its potency in targeting chemo-resistant HCC cells via cancer stemness inhibition. Furthermore, napabucasin also suppressed HCC tumor growth in vivo, accompanied with reduced total STAT3 and p-STAT3 levels and proliferation (Ki-67). Overall, the present study highlighted the prognostic significance of STAT3 in HCC, and its functional role in the control of chemo-resistance and cancer stemness in HCC through targeted therapeutics. Citation Format: Carol Lee, Elaine Yee-Ling OR, Charing Ching-Ning Chong, Tan To Cheung, Iris Ming-Jing Xu, Linda Wing-Chi Ng, Marcus Hung-Lam Law, Peter Tin-Chung Li, Stephen Lam Chan, Anthony Wing-Hung Chan, Philip Chun Yeung, Kelvin Kwok-Chai Ng, Paul Bo-San Lai, Siu Tim Cheung. STAT3 regulates chemo-resistance and cancer stemness in hepatocellular carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4151.

Electroacupuncture ameliorates mechanical hypersensitivity by down-regulating spinal Janus kinase 2/signal transducer and activation of transcription 3 and interleukin 6 in rats with spared nerve injury.

Evidence shows that the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway participates in the pathogenesis of neuropathic pain. Our previous study revealed that electroacupuncture (EA) attenuated neuropathic pain via activation of alpha-7 nicotinic acetylcholine receptor (α7nAChR) in the spinal cord. However, whether 2 Hz EA alleviates neuropathic pain by regulating the downstream molecules JAK2/STAT3 has not been fully clarified. Paw withdrawal threshold (PWT) was used as a marker of mechanical allodynia in rats with spared nerve injury (SNI). After applying 2 Hz EA on day 3, 7, 14 and 21 post-surgery, spinal expression of JAK2, STAT3 and pro-inflammatory cytokine interleukin (IL)-6 was examined using quantitative reverse transcription and real-time polymerase chain reaction (qRT-PCR) and Western blot analysis. Intrathecal injection of the α7nAChR antagonist alpha-bungarotoxin (α-Bgtx) was used to further explore the mechanism underlying the effects of 2 Hz EA on expression of JAK2/STAT3 in SNI rats. It was found that levels of spinal STAT3 and IL-6 mRNA, as well as levels of phosphorylated (p)-JAK2, p-STAT3 and IL-6 protein, were markedly increased in SNI rats. 2 Hz EA attenuated the SNI-induced up-regulation of p-JAK2, p-STAT3 and IL-6 expression in the spinal cord. Furthermore, intrathecal injection of α-Bgtx (1.0 μg/kg) not only inhibited the effect of 2 Hz EA on mechanical hypersensitivity but also ameliorated the down-regulation of p-JAK2, p-STAT3 and IL-6 expression induced by 2 Hz EA. This study revealed that 2 Hz EA attenuated SNI-induced mechanical hypersensitivity and the concomitant up-regulation of spinal JAK2, STAT3 and IL-6 in SNI rats, suggesting that suppression of the JAK2/STAT3 signaling pathway might be the mechanism underlying the therapeutic effect of 2 Hz EA on neuropathic pain.

Viscothionin Suppresses Human Non-small Cell Lung Cancer via Inhibiting the STAT3 Signaling Pathway

&#x0D; Lung cancer is a crucial cause of mortality world-wide. Signal transducer and activator of transcription 3 (STAT3) are important signaling factors in malignant diseases and are constantly activated in 22% ~ 65% of non-small cell lung cancer (NSCLC) cells. STAT3 can be activated by interleukin-6 (IL-6) which induces cell growth in various cancer cells. Although viscothionin is studied for various health beneficial effects, the anticancer effect of viscothionin has not been studies so far against lung cancer. Therefore, the purpose of this study was to demonstrate the anticancer effect of a polypeptide, viscothionin in NCI-H460 lung cancer cells, which represents NSCLC. To do this, cultured NCI-H460 cells were treated with viscothionin and/or IL-6, and the cell viability, as well as expression levels of STAT3, Akt, mTOR, Bax, Bcl-2, and Bcl-xL, including caspase-3 after activity were assessed. As a result, cell viability was decreased in the viscothionin-treated group as compared to control. Also, viscothionin significantly decreased STAT3, Akt and mTOR protein expression levels in NCI-H460 cells. Additionally, the levels of the Bax, an apoptotic protein were increased than the control group, whereas the expression levels of anti-apoptotic proteins Bcl-2 and Bcl-xL were decreased than the control group. Protein level of IL-6 shows the reversible effect compared to viscothionin. Taken together, these results demonstrate that viscothionin exhibits potent anticancer effect in NSCLC through STAT3 inhibition, and could be considered a natural agent of lung cancer therapy.

Retraction Note: Fatty acids and cancer-amplified ZDHHC19 promote STAT3 activation through S-palmitoylation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Promotion of Adropin Expression by Hyperglycemia Is Associated with STAT3 Activation in Diabetic Rats.

BackgroundAdropin is a secreted polypeptide that has been demonstrated to play an important role in energy homeostasis and lipid metabolism. Signal transducer and activator of transcription 3 (STAT3) may promote the transcription of target genes including adropin. In the current study, we investigated the effect of adropin on glucose metabolism in diabetic rats and the mechanism that governs this effect was subsequently assessed.Materials and MethodsRats received a single injection of streptozotocin to induce type 1 diabetes. The diabetic rats were treated with insulin or phloridzin, another antidiabetic agent through inhibition of glucose reabsorption, for 7 days. Plasma glucose levels and adropin levels were measured. The interaction between STAT3 and adropin was evaluated using the human hepatoma HepG2 cell line. HepG2 cells were pretreated with the specific antagonist Stattic or with STAT3-specific siRNAs to knockout STAT3. Changes in energy homeostasis-associated gene expression were measured using real-time PCR. The protein expression levels of pSTAT3 and STAT3 were measured using Western blotting.ResultsIn diabetic rats, the serum concentrations of adropin were increased in the vehicle-treated group and decreased in the insulin- or phloridzin-treated group. In liver tissues, the Enho expression level and the activity of STAT3 also showed similar tendencies. After HepG2 cells were treated with medium containing high glucose, the ratio of p-STAT3 to STAT3, Enho mRNA levels and reactive oxygen species expression levels in HepG2 cells were significantly increased in conjunction with increased glucose levels. The effect was inhibited after pretreatment with Stattic or knockdown with STAT3-specific siRNAs.ConclusionSTAT3 is involved in the genetic regulation of adropin, increasing the levels of circulating adropin and promoting Enho expression in the livers of diabetic rats.