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Ets-1 is a transcriptional mediator of oncogenic nitric oxide signaling in estrogen receptor-negative breast cancer.

ABSTRACT: The Ets-1 transcription factor is a candidate breast cancer oncogene that regulates the expression of genes involved in tumor progression and metastasis. Ets-1 signaling has also been linked to the development of a basal-like breast cancer phenotype. We recently described a nitric oxide (NO)-induced gene signature that is associated with poor disease outcome in estrogen receptor-negative (ER-) breast cancer and contains both stem cell-like and basal-like components. Thus, we examined the role of Ets-1 in NO signaling and NO-induced phenotypes in ER- human breast cancer cells.Promoter region analyses were performed on genes upregulated in inducible nitric oxide synthase (NOS2) high expressing tumors for Ets-binding sites. In vitro mechanisms were examined in human basal-like breast cancer cells lines. NO signaling effects were studied using either forced NOS2 expression or the use of a chemical NO-donor, diethlylenetriamine NONOate (DETANO).Promoter region analysis of genes that are up-regulated in human ER-negative breast tumors with high NOS2 expression revealed that the Ets-binding sequence is the only common promoter element present in all of these genes, indicating that Ets-1 is the key transcriptional factor down-stream of oncogenic NOS2-signaling. Accordingly, both forced NOS2 over-expression and exposure to NO-donors resulted in significant Ets-1 transcriptional activation in ER- breast cancer cells. Functional studies showed that NO activated Ets-1 transcriptional activity via a Ras/MEK/ERK signaling pathway by a mechanism that involved Ras S-nitrosylation. RNA knock-down of Ets-1 suppressed NO-induced expression of selected basal-like breast cancer markers such as P-cadherin, S100A8, IL-8 and ??-crystallin. Additionally, Ets-1 knock-down reduced NO-mediated cellular proliferation, matrix metalloproteinase and cathepsin B activities, as well as matrigel invasion.These data show that Ets-1 is a key transcriptional mediator of oncogenic NO signaling that promotes the development of an aggressive disease phenotype in ER- breast cancer in an Ets-1 and Ras-dependent manner, providing novel clues of how NOS2 expression in human breast tumors is functionally linked to poor patient survival.

SUBMITTER: Switzer CH

PROVIDER: S-EPMC4053102 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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Ets-1 is a transcriptional mediator of oncogenic nitric oxide signaling in estrogen receptor-negative breast cancer.

Switzer Christopher H CH Cheng Robert Y-S RY Ridnour Lisa A LA Glynn Sharon A SA Ambs Stefan S Wink David A DA

Breast cancer research : BCR 20120912 5

<h4>Introduction</h4>The Ets-1 transcription factor is a candidate breast cancer oncogene that regulates the expression of genes involved in tumor progression and metastasis. Ets-1 signaling has also been linked to the development of a basal-like breast cancer phenotype. We recently described a nitric oxide (NO)-induced gene signature that is associated with poor disease outcome in estrogen receptor-negative (ER-) breast cancer and contains both stem cell-like and basal-like components. Thus, we ...[more]

PMID: 22971289

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Project description:The expression of denitrification by a facultatively anaerobic bacterium requires as exogenous signals a low oxygen tension concomitant with an N oxide. We have studied the role of nitric oxide (NO), nitrous oxide (N2O), and nitrite as signal molecules for the expression of the denitrification apparatus of Pseudomonas stutzeri. Transcriptional kinetics of structural genes were monitored by Northern blot analysis in a 60-min time frame after cells were exposed to an N oxide signal. To differentiate the inducer role of NO from that of nitrite, mRNA kinetics were monitored under anoxic conditions in a nirF strain, where NO generation from nitrite is prevented because of a defect in heme D(1) biosynthesis. NO-triggered responses were monitored from the nirSTB operon (encoding cytochrome cd(1) nitrite reductase), the norCB operon (encoding NO reductase), nosZ (encoding nitrous oxide reductase), and nosR (encoding a putative regulator). Transcription of nirSTB and norCB was activated by 5 to 50 nM NO, whereas the nosZ promoter required about 250 nM. Nitrite at 5 to 50 nM elicited no response. At a threshold concentration of 650 nM N2O, we observed in the anoxic cell the transient appearance of nosZ and nosR transcripts. Constant levels of transcripts of both genes were observed in an anoxic cell sparged with N2O. NO at 250 nM stimulated in this cell type the expression of nos genes severalfold. The transcription factor DnrD, a member of the FNR-CRP family, was found to be part of the NO-triggered signal transduction pathway. However, overexpression of dnrD in an engineered strain did not result in NirS synthesis, indicating a need for activation of DnrD. NO modified the transcriptional pattern of the dnrD operon by inducing the transcription of dnrN and dnrO, located upstream of dnrD. Insertional mutagenesis of dnrN altered the kinetic response of the nirSTB operon towards nitrite. Our data establish NO and DnrD as key elements in the regulatory network of denitrification in P. stutzeri. The NO response adds to the previously identified nitrate-nitrite response mediated by the NarXL two-component system for the expression of respiratory nitrate reductase encoded by the narGHJI operon.

Project description:Osteoarthritis (OA) is an aging-associated disease of diarthrodial joints that involves changes in the bone, cartilage and soft tissue. Chondrocytes are the only cell type in cartilage and play a pivotal role in tissue homeostasis and cartilage remodeling in OA. Age- or OA-dependent metabolic changes affecting extracelluar matrix composition as well as variations in the response to cytokines and growth factors have been investigated in human chondrocytes. However, the molecular mechanisms causing age-dependent variation of the chondrocyte phenotype are poorly characterized. The proinflammatory mediator nitric oxide (NO) is produced when chondrocytes are exposed to cytokines such as IL-1. NO affects the energy metabolism of cells through interfering with mitochondrial respiration and glycolysis and has been implicated in extracellular matrix synthesis and degradation and chondrocyte death. NO may contribute to the aging process by compromising the energy balance ! in chondrocytes through the generation of an oxidizing environment and this may in turn affect matrix gene expression. In human chondrocytes NO effects on the expression of extacelluar matrix genes or genes related to matrix structure have not been addressed comprehensively. In chondrocytes NO has profound effects on extracellular matrix: Interleukin-1 induced the production of nitric oxide in human articular chondrocytes in alginate culture and simultaneously inhibited the biosynthesis of proteoglycans. NG-monomethyl-L-arginine (L-NMMA) inhibited nitric oxide formation and the suppression of proteoglycan synthesis. The nitric oxide donor, S-nitrosyl-acetyl-D,L- penicillamine (SNAP) also inhibited proteoglycan biosynthesis suggesting that interleukin-1 suppresses matrix synthesis through mechanisms involving the production of NO. Slices of rabbit articular cartilage synthesized large quantities of nitric oxide (NO) following exposure to IL-1 and strongly suppressed the incorporation of 35SO4 into the glycosaminoglycans (GAGs) of cartilage proteoglycans. Simultaneous treatment of cartilage fragments with IL-1 and L-NMMA inhibited NO synthesis in response to IL-1 and restored proteoglycan synthesis. SNAP reversibly mimicked the effect! of IL-1 on proteoglycan synthesis. These data suggest that endogenously synthesized NO is the mediator which reduces cartilage proteoglycan synthesis in response to cytokines such as IL-1. Aggrecan and type II collagen synthesis are also affected by NO. Our hypothesis entails that in human chondrocytes endogenous NO modulates the expression of matrix genes as well as enzymes involved in extracellular matrix remodelling. Experimental approach: In this experiment cultured chondrocytes from 3 donors was left unstimulated (control) or stimulated with IL-1, L-NMMA or IL-1 + L-NMMA for a period of 8 days in order to achieve sufficiently high levels of intracellular NO and stable expression of a subset of genes. Total RNA was isolated using the Trizol procedure. Gene expression will be probed using the Glycov2 chip.

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Ets-1 is a transcriptional mediator of oncogenic nitric oxide signaling in estrogen receptor-negative breast cancer.

Publications

Ets-1 is a transcriptional mediator of oncogenic nitric oxide signaling in estrogen receptor-negative breast cancer.

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