Gene Summary

Gene:STAT3; signal transducer and activator of transcription 3 (acute-phase response factor)
Summary:The protein encoded by this gene is a member of the STAT protein family. In response to cytokines and growth factors, STAT family members are phosphorylated by the receptor associated kinases, and then form homo- or heterodimers that translocate to the cell nucleus where they act as transcription activators. This protein is activated through phosphorylation in response to various cytokines and growth factors including IFNs, EGF, IL5, IL6, HGF, LIF and BMP2. This protein mediates the expression of a variety of genes in response to cell stimuli, and thus plays a key role in many cellular processes such as cell growth and apoptosis. The small GTPase Rac1 has been shown to bind and regulate the activity of this protein. PIAS3 protein is a specific inhibitor of this protein. Three alternatively spliced transcript variants encoding distinct isoforms have been described. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:signal transducer and activator of transcription 3
Source:NCBIAccessed: 17 August, 2015


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 17 August 2015 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 17 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: STAT3 (cancer-related)

Chen H, Wu Q
Expression of GW112 and GRIM-19 in colorectal cancer tissues.
J BUON. 2015 Mar-Apr; 20(2):438-42 [PubMed] Related Publications
PURPOSE: To investigate the expression of GW112 and GRIM-19 in colorectal cancer tissues.
METHODS: Immunohistochemistry and semi-quantitative PCR were used to simultaneously detect the levels of expression of GW112 and GRIM-19 in colorectal cancer tissues and normal colorectal tissues in 39 cases.
RESULTS: Expression of GW112 protein and mRNA were significantly higher in colorectal cancer tissues than in normal tissues (p<0.05). Expression of GRIM-19 protein and mRNA were significantly lower in colorectal cancer tissues than in normal tissues (p<0.05). GW112 gene mRNA copy number(GAPDH gene mRNA copy number were 0.53 ± 0.21 and 1.81 ± 0.65 in normal colorectal tissues and colorectal cancer tissues respectively, and GRIM-19 gene mRNA copy number/GAPDH gene mRNA copy number were 1.15 ± 0.29 and 1.74 ± 0.0.44 in colorectal cancer tissues and normal colorectal tissues, respectively. Expression of GW112 gene mRNA was significantly higher in colorectal cancer tissues than in normal tissues (p<0.05), and expression of GRIM- 19 gene mRNA was significantly lower in colorectal cancer tissues than in normal tissues (p<0.05).
CONCLUSION: High expression of GW112 in colorectal cancer tissues and reduced expression of GRIM-19 in colorectal cancer tissues may be associated with abnormal proliferation of cancer cells and are possibly one of the reasons for development of colorectal cancer, which can provide effective targets for clinical treatment of this disease.

Kato M, Muromoto R, Togi S, et al.
PML suppresses IL-6-induced STAT3 activation by interfering with STAT3 and HDAC3 interaction.
Biochem Biophys Res Commun. 2015; 461(2):366-71 [PubMed] Related Publications
The promyelocytic leukemia protein PML acts as a tumor suppressor by forming transcription-regulatory complexes with a variety of repressor proteins. In the present study, we found that endogenous PML suppresses interleukin (IL)-6-induced gene expression as well as phosphorylation and transcriptional activation of STAT3 in hepatoma cells. We also found that PML-mediated suppression of IL-6-induced STAT3 activation by disrupting interactions between STAT3 and HDAC3. These results indicate that PML modulates IL-6-induced STAT3 activation and hepatoma cell growth by interacting with HDAC3.

Crescenzo R, Abate F, Lasorsa E, et al.
Convergent mutations and kinase fusions lead to oncogenic STAT3 activation in anaplastic large cell lymphoma.
Cancer Cell. 2015; 27(4):516-32 [PubMed] Related Publications
A systematic characterization of the genetic alterations driving ALCLs has not been performed. By integrating massive sequencing strategies, we provide a comprehensive characterization of driver genetic alterations (somatic point mutations, copy number alterations, and gene fusions) in ALK(-) ALCLs. We identified activating mutations of JAK1 and/or STAT3 genes in ∼20% of 88 [corrected] ALK(-) ALCLs and demonstrated that 38% of systemic ALK(-) ALCLs displayed double lesions. Recurrent chimeras combining a transcription factor (NFkB2 or NCOR2) with a tyrosine kinase (ROS1 or TYK2) were also discovered in WT JAK1/STAT3 ALK(-) ALCL. All these aberrations lead to the constitutive activation of the JAK/STAT3 pathway, which was proved oncogenic. Consistently, JAK/STAT3 pathway inhibition impaired cell growth in vitro and in vivo.

Yoon J, Ko YS, Cho SJ, et al.
Signal transducers and activators of transcription 3-induced metastatic potential in gastric cancer cells is enhanced by glycogen synthase kinase-3β.
APMIS. 2015; 123(5):373-82 [PubMed] Related Publications
The transcription factor signal transducers and activators of transcription 3 (STAT3) can promote cancer metastasis, but its underlying regulatory mechanisms in gastric cancer cell invasiveness still remain obscure. We investigated the relationship between STAT3 and glycogen synthase kinase-3β (GSK-3β) and its significance in metastatic potential in gastric cancer cells. Immunohistochemical tissue array analysis of 267 human gastric carcinoma specimens showed that the expressions of active forms of STAT3 (pSTAT3) and GSK-3β (pGSK-3β) were found in 68 (25%) and 124 (46%) of 267 gastric cancer cases, respectively, showing a positive correlation (p < 0.001). Cell culture experiments using gastric cancer cell lines SNU-638 and SNU-668 revealed that STAT3 suppression did not affect pGSK-3β expression, whereas GSK-3β inhibition reduced pSTAT3 expression. With respect to metastatic potential in gastric cancer cells, both STAT3 suppression and GSK-3β inhibition decreased cell migration, invasion, and mesenchymal marker (Snail, Vimentin, and MMP9) expression. Moreover, the inhibitory effects of STAT3 and GSK-3β on cell migration were synergistic. These results demonstrated that STAT3 and GSK-3β are positively associated and synergistically contribute to metastatic potential in gastric cancer cells. Thus, dual use of STAT3 and GSK-3β inhibitors may enhance the efficacy of the anti-metastatic treatment of gastric cancer.

Liu X, Wang J, Wang H, et al.
REG3A accelerates pancreatic cancer cell growth under IL-6-associated inflammatory condition: Involvement of a REG3A-JAK2/STAT3 positive feedback loop.
Cancer Lett. 2015; 362(1):45-60 [PubMed] Related Publications
Regenerating gene protein (REG) 3A is a 19 kD secretory pancreas protein with pro-growth function. Previously we demonstrated that overexpression of REG3A, acting as a key molecule for up-regulation of the JAK2/STAT3 pathway, contributed to inflammation-related pancreatic cancer (PaC) development. However the exact network associated with REG3A signaling still remains unclear. Here we determined that exposure of human PaC cells to cytokine IL-6 activated the oncogenic JAK2/STAT3 pathway, which directly upregulated REG3A expression, accelerated cell cycle progression by promoting CyclinD1 expression, and enhancing the expression of the anti-apoptosis Bcl family. Importantly, the activation of REG3A would instead enhance the JAK2/STAT3 pathway to constitute a REG3A-JAK2/STAT3 positive feedback loop, which leads to the amplification of the oncogenic effects of IL-6/JAK2/STAT3, a classic pathway linking to inflammation-related tumorigenesis, ultimately resulting in PaC cell over-proliferation and tumor formation both in vitro and in vivo. Moreover, EGFR was found to mediate the REG3A signal for PaC cell growth and JAK2/STAT3 activation, thus functioning as a REG3A receptor. Collectively, our results provide the first evidence for the presence of the synergistic effect of REG3A and IL-6 on PaC development via a REG3A-JAK2/STAT3 positive feedback loop.

Zhou C, Jiao Y, Wang R, et al.
STAT3 upregulation in pituitary somatotroph adenomas induces growth hormone hypersecretion.
J Clin Invest. 2015; 125(4):1692-702 [PubMed] Free Access to Full Article Related Publications
Pituitary somatotroph adenomas result in dysregulated growth hormone (GH) hypersecretion and acromegaly; however, regulatory mechanisms that promote GH hypersecretion remain elusive. Here, we provide evidence that STAT3 directly induces somatotroph tumor cell GH. Evaluation of pituitary tumors revealed that STAT3 expression was enhanced in human GH-secreting adenomas compared with that in nonsecreting pituitary tumors. Moreover, STAT3 and GH expression were concordant in a somatotroph adenoma tissue array. Promoter and expression analysis in a GH-secreting rat cell line (GH3) revealed that STAT3 specifically binds the Gh promoter and induces transcription. Stable expression of STAT3 in GH3 cells induced expression of endogenous GH, and expression of a constitutively active STAT3 further enhanced GH production. Conversely, expression of dominant-negative STAT3 abrogated GH expression. In primary human somatotroph adenoma-derived cell cultures, STAT3 suppression with the specific inhibitor S3I-201 attenuated GH transcription and reduced GH secretion in the majority of derivative cultures. In addition, S3I-201 attenuated somatotroph tumor growth and GH secretion in a rat xenograft model. GH induced STAT3 phosphorylation and nuclear translocation, indicating a positive feedback loop between STAT3 and GH in somatotroph tumor cells. Together, these results indicate that adenoma GH hypersecretion is the result of STAT3-dependent GH induction, which in turn promotes STAT3 expression, and suggest STAT3 as a potential therapeutic target for pituitary somatotroph adenomas.

Dasgupta M, Dermawan JK, Willard B, Stark GR
STAT3-driven transcription depends upon the dimethylation of K49 by EZH2.
Proc Natl Acad Sci U S A. 2015; 112(13):3985-90 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
Several transcription factors, including p53, NF-κB, and STAT3, are modified by the same enzymes that also modify histones, with important functional consequences. We have identified a previously unrecognized dimethylation of K49 of STAT3 that is crucial for the expression of many IL-6-dependent genes, catalyzed by the histone-modifying enzyme enhancer of zeste homolog 2 (EZH2). Loss of EZH2 is protumorigenic in leukemias, but its overexpression is protumorigenic in solid cancers. Connecting EZH2 to a functionally important methylation of STAT3, which is constitutively activated in many tumors, may help reveal the basis of the opposing roles of EZH2 in liquid and solid tumors and also may identify novel therapeutic opportunities.

Liu H, Ren G, Wang T, et al.
Aberrantly expressed Fra-1 by IL-6/STAT3 transactivation promotes colorectal cancer aggressiveness through epithelial-mesenchymal transition.
Carcinogenesis. 2015; 36(4):459-68 [PubMed] Article available free on PMC after 30/09/2015 Related Publications
The pro-inflammatory cytokine interleukin-6 (IL-6) in tumor microenvironment has been suggested to promote development and progression of colorectal cancer (CRC). However, the underlying molecular mechanisms remain elusive. In this study, we demonstrate that fos-related antigen-1 (Fra-1) plays a critical role in IL-6 induced CRC aggressiveness and epithelial-mesenchymal transition (EMT). In CRC cell lines, the expression of Fra-1 gene was found significantly upregulated during IL-6-driven EMT process. The Fra-1 induction occurred at transcriptional level in a manner dependent on signal transducer and activator of transcription 3 (STAT3), during which both phosphorylated and acetylated post-translational modifications were required for STAT3 activation to directly bind to the Fra-1 promoter. Importantly, RNA interference-based attenuation of either STAT3 or Fra-1 prevented IL-6-induced EMT, cell migration and invasion, whereas ectopic expression of Fra-1 markedly reversed the STAT3-knockdown effect and enhanced CRC cell aggressiveness by regulating the expression of EMT-promoting factors (ZEB1, Snail, Slug, MMP-2 and MMP-9). Furthermore, Fra-1 levels were positively correlated with the local invasion depth as well as lymph node and liver metastasis in a total of 229 CRC patients. Intense immunohistochemical staining of Fra-1 was observed at the tumor marginal area adjacent to inflammatory cells and in parallel with IL-6 secretion and STAT3 activation in CRC tissues. Together, this study proposes the existence of an aberrant IL-6/STAT3/Fra-1 signaling axis leading to CRC aggressiveness through EMT induction, which suggests novel therapeutic opportunities for the malignant disease.

Chen M, Liu Y, Varley P, et al.
High-Mobility Group Box 1 Promotes Hepatocellular Carcinoma Progression through miR-21-Mediated Matrix Metalloproteinase Activity.
Cancer Res. 2015; 75(8):1645-56 [PubMed] Article available free on PMC after 15/04/2016 Related Publications
Liver inflammation plays a critical role in hepatocellular carcinoma (HCC) etiology. Damage-associated molecular patterns (DAMP), such as high-mobility group box 1 (HMGB1), and dysregulated miRNAs involved in inflammatory disease states, such as miR-21, may participate in the link between inflammation and cancer. We sought to determine the role of HMGB1 signaling in HCC tumor progression. We first document the concordant expression increase of HMGB1 and miR-21 in HCC cell lines and primary HCC tumor samples and subsequently show that HMGB1 stimulation results in overexpression of miR-21. These changes were found to be dependent on the IL6/STAT3 signaling axis. Invasion and migration of HCC cells in vitro were inhibited by both STAT3 and miR-21 antagonists, suggesting a role for this pathway in HCC tumor progression. We verified that HMGB1-induced expression of miR-21 in HCC provides a posttranscriptional repression of the matrix metalloproteinase (MMP) inhibitors RECK and TIMP3, which are known to impact HCC progression and metastases. Finally, we found that inhibition of miR-21 in murine HMGB1-overexpressing HCC xenografts led to reduced tumor MMP activity through released repression of the miR-21 targets RECK and TIMP3, which ultimately impeded tumor progression. The prototypical DAMP, HMGB1, is released during liver inflammation and provides a favorable environment for HCC growth. HMGB1 signaling increases miR-21 expression to mediate the enhanced activity of MMPs through RECK and TIMP3. These findings provide a novel mechanism for HMGB1-mediated HCC progression through the IL6/Stat3-miR-21 axis.

Siatecka M, Soni S, Planutis A, Bieker JJ
Transcriptional activity of erythroid Kruppel-like factor (EKLF/KLF1) modulated by PIAS3 (protein inhibitor of activated STAT3).
J Biol Chem. 2015; 290(15):9929-40 [PubMed] Article available free on PMC after 10/04/2016 Related Publications
Erythroid Kruppel-like factor (EKLF or KLF1) is a transcription factor crucial for red cell development that is directly involved in regulation of a large number of erythroid genes. EKLF serves mostly as an activator of expression of these genes; however, it can act also as a repressor. Here, we present evidence that EKLF interacts with proteins from the PIAS (protein inhibitor of activated STAT) family that convey repressive activity to EKLF in the absence of sumoylation. Our studies identify PIAS3 as a transcriptional corepressor of EKLF for at least a subset of its target genes during erythropoiesis (e.g. β-globin, α-hemoglobin stabilizing protein). We demonstrate an interaction between EKLF and PIAS proteins confirmed by in vivo coimmunoprecipitation assays with both exogenous and endogenous proteins. We identified an LXXLL signature motif located near the N terminus of PIAS proteins that, although not involved in the EKLF-PIAS3 interaction, is required for the transrepression activity. Knockdown of endogenous PIAS3 accelerates differentiation of both murine erythroleukemia cells, as well as fetal liver cells, whereas an increase in PIAS3 levels inhibits this increase. Using chromatin immunoprecipitation assays, we show that PIAS3 preferentially occupies the β-globin promoter in undifferentiated murine erythroleukemia cells. Together these results demonstrate that an interaction between EKLF and PIAS3 provides a novel mode of regulation of EKLF activity in the absence of sumolylation and furthermore shows an important involvement of PIAS proteins in erythropoiesis.

Lee JH, Kim C, Kim SH, et al.
Farnesol inhibits tumor growth and enhances the anticancer effects of bortezomib in multiple myeloma xenograft mouse model through the modulation of STAT3 signaling pathway.
Cancer Lett. 2015; 360(2):280-93 [PubMed] Related Publications
Aberrant activation of signal transducer and activator of transcription 3 (STAT3) is frequently observed in multiple myeloma (MM) cancer and can upregulate the expression of several genes involved in proliferation, survival, metastasis, and angiogenesis. The effect of farnesol (FOH) on STAT3 activation, associated protein kinases, its regulated gene products, cellular proliferation, and apoptosis was examined. The in vivo effect of FOH on the growth of human MM xenograft tumors alone and in combination with bortezomib (Bor) in athymic nu/nu female mice was also investigated. We found that FOH suppressed both constitutive and inducible STAT3 activation at Tyr705 in MM cells. The suppression of STAT3 was mediated through the inhibition of activation of upstream JAK1, JAK2, and c-Src kinases. Also, treatment with the protein tyrosine phosphatase (PTP) inhibitor, pervanadate treatment reversed the FOH-induced down-regulation of STAT3, possibly indicating the involvement of a PTP. Indeed, we found that FOH treatment induces the increased expression of SHP-2 protein and knockdown of the SHP-2 gene by small interfering RNA suppressed the ability of FOH to inhibit STAT3 activation. FOH inhibited proliferation and significantly potentiated the apoptotic effects of bortezomib (Bor) in U266 cells. When administered intraperitoneally, FOH enhanced Bor-induced growth suppression of human MM xenograft tumors in athymic nu/nu female mice. Our results suggest that FOH is a novel blocker of STAT3 signaling pathway and exerts both anti-proliferative and apoptotic activities in MM in vitro and in vivo.

Sun F, Xiao Y, Qu Z
Oncovirus Kaposi sarcoma herpesvirus (KSHV) represses tumor suppressor PDLIM2 to persistently activate nuclear factor κB (NF-κB) and STAT3 transcription factors for tumorigenesis and tumor maintenance.
J Biol Chem. 2015; 290(12):7362-8 [PubMed] Article available free on PMC after 20/03/2016 Related Publications
Kaposi sarcoma herpesvirus (KSHV) is the most common cause of malignancies among AIDS patients. However, how KSHV induces tumorigenesis remains largely unknown. Here, we demonstrate that one important mechanism underlying the tumorigenesis of KSHV is through transcriptional repression of the tumor suppressor gene PDZ-LIM domain-containing protein 2 (PDLIM2). PDLIM2 expression is repressed in KSHV-transformed human umbilical vascular endothelial cells as well as in KSHV-associated cancer cell lines and primary tumors. Importantly, PDLIM2 repression is essential for KSHV-induced persistent activation of nuclear factor κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) and subsequent tumorigenesis and tumor maintenance. Our mechanistic studies indicate that PDLIM2 repression by KSHV involves DNA methylation. Notably, the epigenetic repression of PDLIM2 can be reversed by 5-aza-2-deoxycytidine and vitamin D to suppress KSHV-associated cancer cell growth. These studies not only improve our understanding of KSHV pathogenesis but also provide immediate therapeutic strategies for KSHV-mediated cancers, particularly those associated with AIDS.

Chen Y, Terajima M, Yang Y, et al.
Lysyl hydroxylase 2 induces a collagen cross-link switch in tumor stroma.
J Clin Invest. 2015; 125(3):1147-62 [PubMed] Article available free on PMC after 20/03/2016 Related Publications
Epithelial tumor metastasis is preceded by an accumulation of collagen cross-links that heighten stromal stiffness and stimulate the invasive properties of tumor cells. However, the biochemical nature of collagen cross-links in cancer is still unclear. Here, we postulated that epithelial tumorigenesis is accompanied by changes in the biochemical type of collagen cross-links. Utilizing resected human lung cancer tissues and a p21CIP1/WAF1-deficient, K-rasG12D-expressing murine metastatic lung cancer model, we showed that, relative to normal lung tissues, tumor stroma contains higher levels of hydroxylysine aldehyde-derived collagen cross-links (HLCCs) and lower levels of lysine aldehyde-derived cross-links (LCCs), which are the predominant types of collagen cross-links in skeletal tissues and soft tissues, respectively. Gain- and loss-of-function studies in tumor cells showed that lysyl hydroxylase 2 (LH2), which hydroxylates telopeptidyl lysine residues on collagen, shifted the tumor stroma toward a high-HLCC, low-LCC state, increased tumor stiffness, and enhanced tumor cell invasion and metastasis. Together, our data indicate that LH2 enhances the metastatic properties of tumor cells and functions as a regulatory switch that controls the relative abundance of biochemically distinct types of collagen cross-links in the tumor stroma.

Betts BC, Sagatys EM, Veerapathran A, et al.
CD4+ T cell STAT3 phosphorylation precedes acute GVHD, and subsequent Th17 tissue invasion correlates with GVHD severity and therapeutic response.
J Leukoc Biol. 2015; 97(4):807-19 [PubMed] Article available free on PMC after 01/04/2016 Related Publications
Th17 cells contribute to severe GVHD in murine bone marrow transplantation. Targeted deletion of the RORγt transcription factor or blockade of the JAK2-STAT3 axis suppresses IL-17 production and alloreactivity by Th17 cells. Here, we show that pSTAT3 Y705 is increased significantly in CD4(+) T cells among human recipients of allogeneic HCT before the onset of Grade II-IV acute GVHD. Examination of target-organ tissues at the time of GVHD diagnosis indicates that the amount of RORγt + Th17 cells is significantly higher in severe GVHD. Greater accumulation of tissue-resident Th17 cells also correlates with the use of MTX- compared with Rapa-based GVHD prophylaxis, as well as a poor therapeutic response to glucocorticoids. RORγt is optimally suppressed by concurrent neutralization of TORC1 with Rapa and inhibition of STAT3 activation with S3I-201, supporting that mTOR- and STAT3-dependent pathways converge upon RORγt gene expression. Rapa-resistant T cell proliferation can be totally inhibited by STAT3 blockade during initial allosensitization. We conclude that STAT3 signaling and resultant Th17 tissue accumulation are closely associated with acute GVHD onset, severity, and treatment outcome. Future studies are needed to validate the association of STAT3 activity in acute GVHD. Novel GVHD prevention strategies that incorporate dual STAT3 and mTOR inhibition merit investigation.

Niu F, Li Y, Lai FF, et al.
LB-1 Exerts Antitumor Activity in Pancreatic Cancer by Inhibiting HIF-1α and Stat3 Signaling.
J Cell Physiol. 2015; 230(9):2212-23 [PubMed] Related Publications
Hypoxia is widely present in pancreatic cancer and subsequently causes the overexpression of hypoxia-inducible factor-1α (HIF-1α) and signal transducer and activator of transcription-3 (Stat3). HIF-1α and Stat3 function cooperatively to regulate a number of downstream genes that are implicated in tumorigenesis. Thus, inhibition of HIF-1α and Stat3 is a potential therapeutic strategy for pancreatic cancer. In this study, we explored how LB-1, a novel triptolide (LA) derivative, exerted its antitumor effect through blockade of HIF-1α and Stat3 signaling. Our data showed that LB-1 was able to inhibit the proliferation and colony formation of Mia-PaCa2 and SW1990 cells. LB-1 suppressed HIF-1α protein accumulation by promoting its proteasome degradation and reducing transactivation. Moreover, the silence of HIF-1α by shRNA partially prevented the proliferation inhibition triggered by LB-1. As expected, LB-1 also decreased Stat3 protein accumulation and blocked the physical interactions between HIF-1α/p300/phosphor-Stat3 (p-Stat3) at the pharmacological concentration to reduce VEGF expression, thereby hypoxia-induced angiogenesis. In the Mia-PaCa2 nude xenograft model, therapeutic treatment with LB-1 significantly inhibited tumor growth and had minimal systemic toxicity compared to the mother drug LA. Furthermore, in accordance with in vitro results, HIF-1α activation and Stat3 expression in tumors were blocked by LB-1 through mTOR-dependent pathway. Taken together, these results illustrate that, as a potent inhibitor of HIF-1α and Stat3 signaling, LB-1 exhibits antitumor effect and could be potentially used to treat pancreatic cancer.

Qin A, Yu Q, Gao Y, et al.
Inhibition of STAT3/cyclinD1 pathway promotes chemotherapeutic sensitivity of colorectal caner.
Biochem Biophys Res Commun. 2015; 457(4):681-7 [PubMed] Related Publications
BACKGROUND: Chemotherapeutic resistance indicated the poor prognosis of colorectal cancer.
OBJECTIVE: Our study aimed to investigate the role of STAT3/cyclinD1 pathway in the chemotherapeutic resistance of colorectal cancer.
METHODS: We firstly measured the expression of cyclinD1 in the colorectal cancer tissues using immunohistochemistry in tissue microarray. Then cell viability and apoptosis were investigated in the HT-29 cell lines dealing with recombinant lentivirus and shRNA to increase or decrease cyclinD1 expression. Furthermore, luciferase and ChIP assays were applied to investigate whether STAT3 regulated cyclinD1 expression by binding to its promoter. Finally, we determined whether inhibition of STAT3 could decrease cyclinD1 and increase the chemotherapy sensitivity.
RESULTS: CyclinD1 expression was significantly increased in the cancer cells and high level of cyclinD1 indicated the poor prognosis. Inhibition of cyclinD1 decreased the cell viability assessed by MTT and increased rate of apoptosis when exposed to 5-FU treatment while overexpression of cyclinD1 showed the reverse effect. ChIP assay showed that STAT3 directly bind to cyclinD1 promoter. Subclone of full promoter of cyclinD1 into pGL4 increased the luciferase activity while delete or mutation of any of STAT3 binding sites resulted in reductions of luciferase activity. Inhibition of STAT3 decreased cyclinD1 expression to decrease the cell viability and increase rate of apoptosis when exposed to 5-FU treatment.
CONCLUSIONS: Inhibition of STAT3/cyclinD1 pathway increased the sensitivity of colorectal cancer cell to chemotherapy.

Chen YW, Guo T, Shen L, et al.
Receptor-type tyrosine-protein phosphatase κ directly targets STAT3 activation for tumor suppression in nasal NK/T-cell lymphoma.
Blood. 2015; 125(10):1589-600 [PubMed] Related Publications
Nasal-type natural killer/T-cell lymphoma (NKTCL) is an aggressive disease characterized by frequent deletions on 6q, and constitutive activation of signal transducer and activator of transcription 3 (STAT3). Phosphorylation at Tyr705 activates STAT3, inducing dimerization, nuclear translocation, and DNA binding. In this study, we investigated whether receptor-type tyrosine-protein phosphatase κ (PTPRK), the only protein tyrosine phosphatase at 6q that contains a STAT3-specifying motif, negatively regulates STAT3 activation in NKTCL. PTPRK was highly expressed in normal NK cells but was underexpressed in 4 of 5 (80%) NKTCL cell lines and 15 of 27 (55.6%) primary tumors. Significantly, PTPRK protein expression was inversely correlated with nuclear phospho-STAT3(Tyr705) expression in NKTCL cell lines (P = .025) and tumors (P = .040). PTPRK restoration decreased nuclear phospho-STAT3(Tyr705) levels, whereas knockdown of PTPRK increased such levels in NKTCL cells. Phosphatase substrate-trapping mutant assays demonstrated the binding of PTPRK to STAT3, and phosphatase assays showed that PTPRK directly dephosphorylated phospho-STAT3(Tyr705). Restoration of PTPRK inhibited tumor cell growth and reduced the migration and invasion ability of NKTCL cells. Monoallelic deletion and promoter hypermethylation caused underexpression of PTPRK messenger RNA in NKTCL, and methylation of the PTPRK promoter significantly correlated with inferior overall survival (P = .049) in NKTCL patients treated with the steroid-dexamethasone, methotrexate, ifosfamide, l-asparaginase, and etoposide regimen. Altogether, our findings show that PTPRK underexpression leads to STAT3 activation and contributes to NKTCL pathogenesis.

Yang Z, Liu Y, Liao J, et al.
Quercetin induces endoplasmic reticulum stress to enhance cDDP cytotoxicity in ovarian cancer: involvement of STAT3 signaling.
FEBS J. 2015; 282(6):1111-25 [PubMed] Related Publications
There is an urgent need to make cisplatin (cDDP) more effective and less toxic in the treatment of ovarian cancer for its systemic side effects and high resistance rate. In this study, we investigated the effect of quercetin (Qu) pretreatment on the potentiation of cDDP in ovarian cancer. We found that Qu pretreatment significantly enhanced cDDP cytotoxicity in an ovarian cancer cell line and primary cancer cells. In addition, we demonstrated that Qu elicited obvious endoplasmic reticulum stress (ERS) and activated all three branches of ERS in ovarian cancer. Specific inhibitors of each ERS pathway, as well as the general ERS stabilizer tauroursodeoxycholic acid, notably diminished such enhancing effects. Furthermore, Qu notably suppressed STAT3 phosphorylation, leading to downregulation of the BCL-2 gene downstream of STAT3. Moreover, blocking ERS restored the protein levels of phosphorylated STAT3 as well as BCL-2 expression, thus abolishing the chemosensitization potency of Qu; these results revealed that Qu affected the STAT3 pathway to enhance cDDP cytotoxicity, and this effect involved ERS signaling. In a xenograft mouse model of ovarian cancer, Qu enhanced the antitumor effect of cDDP. Tumors from mice treated with cDDP in combination with Qu pretreatment had repressed STAT3 phosphorylation, lower BCL-2 and higher apoptosis levels compared with those from the other groups. Meanwhile, Qu markedly reduced the elevation of blood creatinine during cDDP intervention. These data indicate that Qu pretreatment potentiates the antitumor effects of cDDP in ovarian cancer while protecting the kidneys against damage. Therefore the strategy of Qu pretreatment may be beneficial in enhancing the therapeutic efficacy of cDDP against ovarian cancer.

Jeon YJ, Jung SN, Yun J, et al.
Ginkgetin inhibits the growth of DU-145 prostate cancer cells through inhibition of signal transducer and activator of transcription 3 activity.
Cancer Sci. 2015; 106(4):413-20 [PubMed] Related Publications
Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in human cancers. Therefore, STAT3 is a therapeutic target of cancer drug discovery. We previously reported that natural products inhibited constitutively activated STAT3 in human prostate tumor cells. We used a dual-luciferase assay to screen 200 natural products isolated from herbal medicines and we identified ginkgetin obtained from the leaves of Ginkgo biloba L. as a STAT3 inhibitor. Ginkgetin inhibited both inducible and constitutively activated STAT3 and blocked the nuclear translocation of p-STAT3 in DU-145 prostate cancer cells. Furthermore, ginkgetin selectively inhibited the growth of prostate tumor cells stimulated with activated STAT3. Ginkgetin induced STAT3 dephosphorylation at Try705 and inhibited its localization to the nucleus, leading to the inhibition of expression of STAT3 target genes such as cell survival-related genes (cyclin D1 and survivin) and anti-apoptotic proteins (Bcl-2 and Bcl-xL). Therefore, ginkgetin inhibited the growth of STAT3-activated tumor cells. We also found that ginkgetin inhibited tumor growth in xenografted nude mice and downregulated p-STAT3(Tyr705) and survivin in tumor tissues. This is the first report that ginkgetin exerts antitumor activity by inhibiting STAT3. Therefore, ginkgetin is a good STAT3 inhibitor and may be a useful lead molecule for development of a therapeutic STAT3 inhibitor.

Nisimova L, Wen S, Cross-Knorr S, et al.
Role of Raf kinase inhibitor protein in Helicobacter pylori-mediated signaling in gastric cancer.
Crit Rev Oncog. 2014; 19(6):469-81 [PubMed] Related Publications
Helicobacter pylori is a helical bacterium that colonizes the stomach in over half of the world's population. Infection with this bacterium has been linked to peptic ulcer disease and gastric cancer. The bacterium has been shown to affect regulatory pathways in its host cells through specific virulence factors that control gene expression. Infection with H. pylori increases levels of phosphorylation of Raf kinase inhibitor protein (pRKIP) in gastric adenocarcinoma (AGS) cells in vitro and in vivo. We investigated the role of H. pylori in the phosphorylation of RKIP as a possible mechanism to downregulate pro-survival signals in gastric adenocarcinoma. pRKIP induces RKIP transcriptional activity, which serves to induce apoptosis of damaged cells to prevent further tumorigenesis. Infection of wild type and RKIP knockout mice with H. pylori for 2 months further confirmed roles of RKIP and pRKIP in the prevention of gastric cancer progression. Loss of RKIP in AGS cells results in increased expression of the Cag A virulence factor after H. pylori infection and RKIP overexpression inhibits H. pylori-mediated STAT3 phosphorylation and STAT3 and NF-κB transcriptional activity. We examined the role of mTOR (mammalian target of rapamycin) after H. pylori infection on the phosphorylation of RKIP. Cells treated with rapamycin, an inhibitor of mTOR, displayed less expression of pRKIP after H. pylori infection. Microarray antibody analysis was conducted on wild-type and RKIP-knockdown AGS cells and showed that in the absence of RKIP, there was increased expression of pro-tumorigenic proteins such as EGFR, Raf-1, and MAPKs. Although further work is needed to confirm the interaction of RKIP and mTOR in AGS cells as a result of H. pylori infection, we hypothesize that H. pylori-mediated induction of pro-survival signaling in gastric epithelial cells induces a feedback response through the activation of RKIP. The phosphorylated, or active, form of RKIP is important in protecting gastric epithelial cells from tumorigenesis after H. pylori infection.

Amano Y, Ishikawa R, Sakatani T, et al.
Oncogenic TPM3-ALK activation requires dimerization through the coiled-coil structure of TPM3.
Biochem Biophys Res Commun. 2015; 457(3):457-60 [PubMed] Related Publications
Inflammatory myofibroblastic tumor (IMT) is a mesenchymal tumor that can arise from anywhere in the body. Anaplastic lymphoma kinase (ALK) gene rearrangements, most often resulting in the tropomyosin 3 (TPM3)-ALK fusion gene, are the main causes of IMT. However, the mechanism of malignant transformation in IMT has yet to be elucidated. The purpose of this study was to clarify the role of the TPM3 region in the transformation of IMT via TPM3-ALK. Lentivirus vectors containing a TPM3-ALK fusion gene lacking various lengths of TPM3 were constructed and expressed in HEK293T and NIH3T3 cell lines. Focus formation assay revealed loss of contact inhibition in NIH3T3 cells transfected with full-length TPM3-ALK, but not with ALK alone. Blue-native polyacrylamide gel electrophoresis (BN-PAGE) revealed that TPM3-ALK dimerization increased in proportion to the length of TPM3. Western blot showed phosphorylation of ALK, ERK1/2, and STAT3 in HEK293T cells transfected with TPM3-ALK. Thus, the coiled-coil structure of TPM3 contributes to the transforming ability of the TPM3-ALK fusion protein, and longer TPM3 region leads to higher dimer formation.

Mazzocca A, Dituri F, De Santis F, et al.
Lysophosphatidic acid receptor LPAR6 supports the tumorigenicity of hepatocellular carcinoma.
Cancer Res. 2015; 75(3):532-43 [PubMed] Related Publications
The aberrant processes driving hepatocellular carcinoma (HCC) are not fully understood. Lysophosphatidic acid receptors (LPAR) are commonly overexpressed in HCC, but their contributions to malignant development are not well established. In this report, we show that aberrant expression of LPAR6 sustains tumorigenesis and growth of HCC. Overexpression of LPAR6 in HCC specimens associated with poor survival in a cohort of 128 patients with HCC. We took a genetic approach to elucidate how LPAR6 sustains the HCC tumorigenic process, including through an expression profiling analysis to identify genes under the control of LPAR6. RNAi-mediated attenuation of LPAR6 impaired HCC tumorigenicity in tumor xenograft assays. Expression profiling and mechanistic analyses identified Pim-3 as a pathophysiologically relevant LPAR6 target gene. In nonmalignant cells where LPAR6 overexpression was sufficient to drive malignant character, Pim-3 was upregulated at the level of transcription initiation through a STAT3-dependent mechanism. A further analysis of HCC clinical specimens validated the connection between overexpression of LPAR6 and Pim-3, high proliferation rates, and poorer survival outcomes. Together, our findings establish LPAR6 as an important theranostic target in HCC tumorigenesis.

Zhang XY, Li M, Sun K, et al.
Decreased expression of GRIM-19 by DNA hypermethylation promotes aerobic glycolysis and cell proliferation in head and neck squamous cell carcinoma.
Oncotarget. 2015; 6(1):101-15 [PubMed] Article available free on PMC after 01/04/2016 Related Publications
To identify novel tumor suppressor genes that are down-regulated by promoter hypermethylation in head and neck squamous cell carcinoma (HNSCC), genome-wide methylation profiling was performed using a methylated DNA immunoprecipitation (MeDIP) array in HNSCC and normal mucosa tissue samples. Promoter hypermethylation of the candidate gene, gene associated with retinoid-interferon induced mortality-19 (GRIM-19), was confirmed in HNSCC cell lines. Multivariate regression analysis determined that GRIM-19 hypermethylation was an independent significant factor for HNSCC diagnosis (OR:125.562; P < 0.001). HNSCC patients with lower ratio of GRIM-19/ACTB hypermethylation had increased overall and disease free survival. Furthermore, the optimal cutoff provided 90% sensitivity and 77% specificity of GRIM-19 hypermethylation as a diagnostic marker for HNSCC. Ectopic expression of GRIM-19 in HNSCC cells led to increased oxygen consumption, reduced glycolysis and decreased cell proliferation. HNSCC cells ectopically expressing GRIM-19 displayed increased p53 activity as well as decreased Stat3 and HIF-1α activities. Moreover, GRIM-19 knockdown not only resulted in decreased oxygen consumption and increased aerobic glycolysis but also promoted cell proliferation and tumorigenic capacity in HNSCC cells. Our data indicate that decreased GRIM-19 expression due to promoter hypermethylation may be important in head and neck carcinogenesis by promoting cell proliferation and regulating metabolic activity.

Wan F, Qin X, Zhang G, et al.
Oxidized low-density lipoprotein is associated with advanced-stage prostate cancer.
Tumour Biol. 2015; 36(5):3573-82 [PubMed] Related Publications
Clinical and epidemiological data suggest coronary artery disease shares etiology with prostate cancer (PCa). The aim of this work was to assess the effects of several serum markers reported in cardiovascular disease on PCa. Serum markers (oxidized low-density lipoprotein [ox-LDL], apolipoprotein [apo] B100, and apoB48) in peripheral blood samples from 50 patients from Fudan University Shanghai Cancer Center (FUSCC) with localized or lymph node metastatic PCa were investigated in this study. Twenty-five samples from normal individuals were set as controls. We first conducted enzyme-linked immunosorbent assay analysis to select candidate markers that were significantly different between these patients and controls. Then, the clinical relevance between OLR1 (the ox-LDL receptor) expression and PCa was analyzed in The Cancer Genome Atlas (TCGA) cohort. We also investigated the function of ox-LDL in PCa cell lines in vitro. Phosphorylation protein chips were used to analyze cell signaling pathways in ox-LDL-treated PC-3 cells. The ox-LDL level was found to be significantly correlated with N stage of prostate cancer. OLR1 expression was correlated with lymph node metastasis in the TCGA cohort. In vitro, ox-LDL stimulated the proliferation, migration, and invasion of LNCaP and PC-3 in a dose-dependent manner. The results of phosphoprotein microarray illustrated that ox-LDL could influence multiple signaling pathways of PC-3. Activation of proliferation promoting signaling pathways (including β-catenin, cMyc, NF-κB, STAT1, STAT3) as well as apoptosis-associating signaling pathways (including p27, caspase-3) demonstrated that ox-LDL had complicated effects on prostate cancer. Increased serum ox-LDL level and OLR1 expression may indicate advanced-stage PCa and lymph node metastasis. Moreover, ox-LDL could stimulate PCa proliferation, migration, and invasion in vitro.

Shishodia G, Verma G, Srivastava Y, et al.
Deregulation of microRNAs Let-7a and miR-21 mediate aberrant STAT3 signaling during human papillomavirus-induced cervical carcinogenesis: role of E6 oncoprotein.
BMC Cancer. 2014; 14:996 [PubMed] Article available free on PMC after 01/04/2016 Related Publications
BACKGROUND: Aberrantly expressed and constitutively active STAT3 signaling plays a pivotal role in initiation and progression of human papillomavirus-induced cervical carcinogenesis. However, the underlying mechanism(s) responsible for pleiotropic effects of STAT3 signaling is poorly understood. In view of emerging regulatory role of microRNAs, Let-7a and miR-21 that may interact with STAT3 signaling and/or its downstream effectors, present study was designed in HPV16-positive cervical cancer cells to assess the functional contribution of these miRs in STAT3 signaling in cervical cancer.
METHODS: Functional silencing of STAT3 signaling and HPV16 oncoprotein expression in SiHa cells was done by STAT3-specific and 16 E6 siRNAs. Pharmacological intervention of STAT3 was done using specific inhibitors like curcumin and stattic. Loss-of-function study of miR-21 using miR-21 inhibitor and gain-of-function study of let-7a was done using let-7a mimic in SiHa cells.
RESULTS: Functional silencing of STAT3 signaling in SiHa cells by STAT3-specific siRNA resulted in a dose-dependent decrease in cellular miR-21 level. Pharmacological intervention of STAT3 using specific inhibitors like curcumin and Stattic that abrogated STAT3 activation resulted in loss of cellular miR-21 pool. Contrary to this, specific targeting of miR-21 using miR-21 inhibitor resulted in an increased level of PTEN, a negative regulator of STAT3, and reduced active pSTAT3 level. Besides miR-21, restoration of cellular Let-7a using chemically synthesized Let-7a mimic reduced overall STAT3 level. Abrogation of HPV oncoprotein E6 by specific siRNA resulted in increased Let-7a but loss of miR-21 and a correspondingly reduced pSTAT3/STAT3 and elevated the level of cellular PTEN.
CONCLUSIONS: Our results demonstrate existence of a functional loop involving Let-7a, STAT3 and miR-21 which were found potentially regulated by viral oncoprotein E6.
IMPLICATIONS: miR-21 and Let-7a along with STAT3 may prove useful targets for pharmacological intervention for management of cervical cancer.

Zou Y, Xiong H, Xiong H, et al.
A polysaccharide from mushroom Huaier retards human hepatocellular carcinoma growth, angiogenesis, and metastasis in nude mice.
Tumour Biol. 2015; 36(4):2929-36 [PubMed] Related Publications
Mushroom Huaier has become a focus of interest in the treatment of hepatocellular carcinoma (HCC). Presently, we isolated and purified one polysaccharide from this mushroom. This study aimed to investigate the effects of SP1 on tumor growth and metastasis in a HCC xenograft model and explore its possible mechanism of action. Our results showed that SP1 not only significantly inhibited the proliferation of SMMC-7721 cells in vitro at the concentration ranging from 0 to 800 μg/ml but also suppressed the HCC tumor growth and metastatic nodules to the lung in SMMC-7721-bearing mice by oral administration at three doses of 30, 60, and 120 mg/kg. Concomitantly, immunohistochemistry analysis of tumor tissues identified that SP1 administration at three doses significantly inhibited the in vivo cancer cell proliferation and microvessel density (MVD) formation, evidenced by a low proliferating cell nuclear antigen (PCNA) and CD34 expression, but increased the percentage of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells. Keeping in line with this observation, SP1 treatment decreased serum matrix metalloproteinase (MMP) 2 and vascular endothelial growth factor (VEGF) levels, downregulated the protein expression of hypoxia-inducible factor (HIF)-1alpha, VEGF, MMP2, bcl-2, N-cadherin, signal transducer and activator of transcription 3 (STAT3), and metadherin (MTDH), and upregulated bax and NE-cadherin protein expression in tumor tissues. Taken together, our data suggest that SP1 appears to be a promising chemopreventive agent for the tumorigenesis and metastasis in patients with HCC, especially at advanced stages.

Alshaker H, Krell J, Frampton AE, et al.
Leptin induces upregulation of sphingosine kinase 1 in oestrogen receptor-negative breast cancer via Src family kinase-mediated, janus kinase 2-independent pathway.
Breast Cancer Res. 2014; 16(5):426 [PubMed] Article available free on PMC after 01/04/2016 Related Publications
INTRODUCTION: Obesity is a known risk factor for breast cancer. Sphingosine kinase 1 (SK1) is an oncogenic lipid kinase that is overexpressed in breast tumours and linked with poor prognosis, however, its role in obesity-driven breast cancer was never elucidated.
METHODS: Human primary and secondary breast cancer tissues were analysed for SK1 and leptin receptor expression using quantitative real-time polymerase chain reaction (qRT-PCR) assay. Leptin-induced signalling was analysed in human oestrogen receptor (ER)-positive and negative breast cancer cells using Western blotting, qRT-PCR and radiolabelling assays.
RESULTS: Our findings show for the first time that human primary breast tumours and associated lymph node metastases exhibit a strong correlation between SK1 and leptin receptor expression (Pearson R = 0.78 and R = 0.77, respectively, P <0.001). Both these genes are elevated in metastases of ER-negative patients and show a significant increase in patients with higher body mass index (BMI). Leptin induces SK1 expression and activation in ER-negative breast cancer cell lines MDAMB-231 and BT-549, but not in ER-positive cell lines. Pharmacological inhibition and gene knockdown showed that leptin-induced SK1 activity and expression are mediated by activation of extracellular signal-regulated kinases 1/2 (ERK1/2) and Src family kinase (SFK) pathways, but not by the major pathways downstream of leptin receptor (LEPR) - janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3). Src-homology 2 domain-containing phosphatase 2 (SHP2) appeared to be key to SK1 activation, and may function as an adaptor protein between SFKs and LEPR. Importantly, leptin-induced breast cancer cell proliferation was abrogated by SK1-specific small interfering RNA (siRNA).
CONCLUSIONS: Overall, our findings demonstrate a novel SFK/ERK1/2-mediated pathway that links leptin signalling and expression of oncogenic enzyme SK1 in breast tumours and suggest the potential significance of this pathway in ER-negative breast cancer.

Zhu J, Wang M, Yu Y, et al.
A novel PI3K inhibitor PIK-C98 displays potent preclinical activity against multiple myeloma.
Oncotarget. 2015; 6(1):185-95 [PubMed] Article available free on PMC after 01/04/2016 Related Publications
Recent clinical trials have demonstrated targeting PI3K pathway is a promising strategy for the treatment of blood cancers. To identify novel PI3K inhibitors, we performed a high throughput virtual screen and identified several novel small molecule compounds, including PIK-C98 (C98). The cell-free enzymatic studies showed that C98 inhibited all class I PI3Ks at nano- or low micromolar concentrations but had no effects on AKT or mTOR activity. Molecular docking analysis revealed that C98 interfered with the ATP-binding pockets of PI3Ks by forming H-bonds and arene-H interactions with specific amino acid residues. The cellular assays demonstrated that C98 specifically inhibited PI3K/AKT/mTOR signaling pathway, but had no effects on other kinases and proteins including IGF-1R, ERK, p38, c-Src, PTEN, and STAT3. Inhibition of PI3K by C98 led to myeloma cell apoptosis. Furthermore, oral administration of C98 delayed tumor growth in two independent human myeloma xenograft models in nude mice but did not show overt toxicity. Pharmacokinetic analyses showed that C98 was well penetrated into myeloma tumors. Therefore, through a high throughput virtual screen we identified a novel PI3K inhibitor that is orally active against multiple myeloma with great potential for further development.

Auphan-Anezin N, Schmitt-Verhulst AM
Silence STAT3 in the procancer niche… and activate CD8+ T cells to kill premetastatic myeloid intruders.
Eur J Immunol. 2015; 45(1):44-8 [PubMed] Related Publications
Several recent studies have implicated myeloid cells in providing a microenvironment that promotes tumor cell survival and metastasis, therefore preparing a "premetastatic niche" for cancer progression. In this issue of the European Journal of Immunology, Zhang et al. [Eur. J. Immunol. 2015. 45: 71-81] address the regulation of immune cells in premetastatic lymph nodes in experimental mouse models. The authors show that signal transducer and activator of transcription 3 (STAT3) ablation in murine myeloid cells, which renders the premetastatic niche less receptive to metastasis by B16 melanoma cells, also leads to local activation in the niche of CD8(+) T cells with increased expression of IFN-γ and granzyme B. Data further suggest that STAT3 activation in the myeloid population leads to poor tumor antigen presenting capacity as well as resistance to CD8(+) T-cell killing. Based on these studies in mice and observations in human cancer patients, the authors propose treatments designed to regulate STAT3 activation, which are correlated with increased cytolytic activity of CD8(+) T cells in mouse models.

Kong LY, Wei J, Haider AS, et al.
Therapeutic targets in subependymoma.
J Neuroimmunol. 2014; 277(1-2):168-75 [PubMed] Related Publications
Subependymomas are usually treated with surgical resection; however, no standard, defined alternative medical therapy is recommended for patients who are not surgical candidates, owing to a paucity of molecular, immunological, and genetic characterization. To address this, an ex vivo functional analysis of the immune microenvironment in subependymoma was conducted, a subependymoma cytokine/chemokine microarray was constructed for the evaluation of operational immune and molecular pathways, and a subependymoma cell line was derived and used to test a variety of cytotoxic agents that target operational pathways identified in subependymoma. We found that immune effectors are detectable within the microenvironment of subependymoma; however, marked immune suppression is not observed. The subependymoma tissue microarrays demonstrated tumor expression of p53, MDM2, HIF-1α, topoisomerase II-β, p-STAT3, and nucleolin, but not EGFRvIII, EphA2, IL-13RA2, CMV, CTLA-4, FoxP3, PD-1, PD-L1, EGFR, PDGF-α, PDGF-β, PDGFR-α, PDGFR-β, PTEN, IGFBP2, PI3K, MDM4, IDH1, mTOR, or Jak2. A topoisomerase inhibitor (WP744, IC50=0.83 μM) and a p-STAT3/HIF-1α inhibitor (WP1066, IC50=3.15 μM) demonstrated a growth inhibition of the subependymoma cell proliferation. Cumulatively, these data suggest that those agents that interfere with oncogenes operational in subependymoma may have clinical impact.

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