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HIF-1?/GPER signaling mediates the expression of VEGF induced by hypoxia in breast cancer associated fibroblasts (CAFs).

ABSTRACT: INTRODUCTION:Carcinoma-associated fibroblasts (CAFs) play a pivotal role in cancer progression by contributing to invasion, metastasis and angiogenesis. Solid tumors possess a unique microenvironment characterized by local hypoxia, which induces gene expression changes and biological features leading to poor outcomes. Hypoxia Inducible Factor 1 (HIF-1) is the main transcription factor that mediates the cell response to hypoxia through different mechanisms that include the regulation of genes strongly associated with cancer aggressiveness. Among the HIF-1 target genes, the G-protein estrogen receptor (GPER) exerts a stimulatory role in diverse types of cancer cells and in CAFs. METHODS:We evaluated the regulation and function of the key angiogenic mediator vascular endothelial growth factor (VEGF) in CAFs exposed to hypoxia. Gene expression studies, Western blotting analysis and immunofluorescence experiments were performed in CAFs and breast cancer cells in the presence of cobalt chloride (CoCl?) or cultured under low oxygen tension (2% O?), in order to analyze the involvement of the HIF-1?/GPER signaling in the biological responses to hypoxia. We also explored the role of the HIF-1?/GPER transduction pathway in functional assays like tube formation in human umbilical vein endothelial cells (HUVECs) and cell migration in CAFs. RESULTS:We first determined that hypoxia induces the expression of HIF-1? and GPER in CAFs, then we ascertained that the HIF-1?/GPER signaling is involved in the regulation of VEGF expression in breast cancer cells and in CAFs exposed to hypoxia. We also assessed by ChIP assay that HIF-1? and GPER are both recruited to the VEGF promoter sequence and required for VEGF promoter stimulation upon hypoxic condition. As a biological counterpart of these findings, conditioned medium from hypoxic CAFs promoted tube formation in HUVECs in a HIF-1?/GPER dependent manner. The functional cooperation between HIF-1? and GPER in CAFs was also evidenced in the hypoxia-induced cell migration, which involved a further target of the HIF-1?/GPER signaling like connective tissue growth factor (CTGF). CONCLUSIONS:The present results provide novel insight into the role elicited by the HIF-1?/GPER transduction pathway in CAFs towards the hypoxia-dependent tumor angiogenesis. Our findings further extend the molecular mechanisms through which the tumor microenvironment may contribute to cancer progression.

SUBMITTER: De Francesco EM

PROVIDER: S-EPMC3978922 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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HIF-1α/GPER signaling mediates the expression of VEGF induced by hypoxia in breast cancer associated fibroblasts (CAFs).

De Francesco Ernestina Marianna EM Lappano Rosamaria R Santolla Maria Francesca MF Marsico Stefania S Caruso Arnaldo A Maggiolini Marcello M

Breast cancer research : BCR 20130101 4

<h4>Introduction</h4>Carcinoma-associated fibroblasts (CAFs) play a pivotal role in cancer progression by contributing to invasion, metastasis and angiogenesis. Solid tumors possess a unique microenvironment characterized by local hypoxia, which induces gene expression changes and biological features leading to poor outcomes. Hypoxia Inducible Factor 1 (HIF-1) is the main transcription factor that mediates the cell response to hypoxia through different mechanisms that include the regulation of g ...[more]

PMID: 23947803

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Project description:BACKGROUND:The G protein estrogen receptor GPER/GPR30 mediates estrogen action in breast cancer cells as well as in breast cancer-associated fibroblasts (CAFs), which are key components of microenvironment driving tumor progression. GPER is a transcriptional target of hypoxia inducible factor 1 alpha (HIF-1?) and activates VEGF expression and angiogenesis in hypoxic breast tumor microenvironment. Furthermore, IGF1/IGF1R signaling, which has angiogenic effects, has been shown to activate GPER in breast cancer cells. METHODS:We analyzed gene expression data from published studies representing almost 5000 breast cancer patients to investigate whether GPER and IGF1 signaling establish an angiocrine gene signature in breast cancer patients. Next, we used GPER-positive but estrogen receptor (ER)-negative primary CAF cells derived from patient breast tumours and SKBR3 breast cancer cells to investigate the role of GPER in the regulation of VEGF expression and angiogenesis triggered by IGF1. We performed gene expression and promoter studies, western blotting and immunofluorescence analysis, gene silencing strategies and endothelial tube formation assays to evaluate the involvement of the HIF-1?/GPER/VEGF signaling in the biological responses to IGF1. RESULTS:We first determined that GPER is co-expressed with IGF1R and with the vessel marker CD34 in human breast tumors (n?=?4972). Next, we determined that IGF1/IGF1R signaling engages the ERK1/2 and AKT transduction pathways to induce the expression of HIF-1? and its targets GPER and VEGF. We found that a functional cooperation between HIF-1? and GPER is essential for the transcriptional activation of VEGF induced by IGF1. Finally, using conditioned medium from CAFs and SKBR3 cells stimulated with IGF1, we established that HIF-1? and GPER are both required for VEGF-induced human vascular endothelial cell tube formation. CONCLUSIONS:These findings shed new light on the essential role played by GPER in IGF1/IGF1R signaling that induces breast tumor angiogenesis. Targeting the multifaceted interactions between cancer cells and tumor microenvironment involving both GPCRs and growth factor receptors has potential in future combination anticancer therapies.

Project description:BackgroundThe chemical carcinogen 3-methylcholanthrene (3MC) binds to the aryl hydrocarbon receptor (AHR) that regulates the expression of cytochrome P450 (CYP) enzymes as CYP1B1, which is involved in the oncogenic activation of environmental pollutants as well as in the estrogen biosynthesis and metabolism. 3MC was shown to induce estrogenic responses binding to the estrogen receptor (ER) ? and stimulating a functional interaction between AHR and ER?. Recently, the G protein estrogen receptor (GPER) has been reported to mediate certain biological responses induced by endogenous estrogens and environmental compounds eliciting an estrogen-like activity.MethodsMolecular dynamics and docking simulations were performed to evaluate the potential of 3MC to interact with GPER. SkBr3 breast cancer cells and cancer-associated fibroblasts (CAFs) derived from breast tumor patients were used as model system. Real-time PCR and western blotting analysis were performed in order to evaluate the activation of transduction mediators as well as the mRNA and protein levels of CYP1B1 and cyclin D1. Co-immunoprecipitation studies were performed in order to explore the potential of 3MC to trigger the association of GPER with AHR and EGFR. Luciferase assays were carried out to determine the activity of CYP1B1 promoter deletion constructs upon 3MC exposure, while the nuclear shuttle of AHR induced by 3MC was assessed through confocal microscopy. Cell proliferation stimulated by 3MC was determined as biological counterpart of the aforementioned experimental assays. The statistical analysis was performed by ANOVA.ResultsWe first ascertained by docking simulations the ability of 3MC to interact with GPER. Thereafter, we established that 3MC activates the EGFR/ERK/c-Fos transduction signaling through both AHR and GPER in SkBr3 cells and CAFs. Then, we found that these receptors are involved in the up-regulation of CYP1B1 and cyclin D1 as well as in the stimulation of growth responses induced by 3MC.ConclusionsIn the present study we have provided novel insights regarding the molecular mechanisms by which 3MC may trigger a physical and functional interaction between AHR and GPER, leading to the stimulation of both SkBr3 breast cancer cells and CAFs. Altogether, our results indicate that 3MC may engage both GPER and AHR transduction pathways toward breast cancer progression.

Project description:BackgroundEpithelial-mesenchymal transition (EMT) of mesothelial cells is a key step in the peritoneal fibrosis (PF). Recent evidence indicates that signal transducer and activator of transcription 3 (STAT3) might mediate the process of renal fibrosis, which could induce the expression of hypoxia-inducible factor-1α (HIF-1α). Here, we investigated the effect of STAT3 activation on HIF-1α expression and the EMT of mesothelial cells, furthermore the role of pharmacological blockade of STAT3 in the process of PF during peritoneal dialysis (PD) treatment.MethodsFirstly, we investigated the STAT3 signaling in human peritoneal mesothelial cells (HPMCs) from drained PD effluent. Secondly, we explored the effect of STAT3 signaling activation on the EMT and the expression of HIF-1α in human mesothelial cells (Met-5A) induced by high glucose. Finally, peritoneal fibrosis was induced by daily intraperitoneal injection with peritoneal dialysis fluid (PDF) so as to explore the role of pharmacological blockade of STAT3 in this process.ResultsCompared with the new PD patient, the level of phosphorylated STAT3 was up-regulated in peritoneal mesothelial cells from long-term PD patients. High glucose (60 mmol/L) induced over-expression of Collagen I, Fibronectin, α-SMA and reduced the expression of E-cadherin in Met-5A cells, which could be abrogated by STAT3 inhibitor S3I-201 pretreatment as well as by siRNA for STAT3. Furthermore, high glucose-mediated STAT3 activation in mesothelial cells induced the expression of HIF-1α and the profibrotic effect of STAT3 signaling was alleviated by siRNA for HIF-1α. Daily intraperitoneal injection of high-glucose based dialysis fluid (HG-PDF) induced peritoneal fibrosis in the mice, accompanied by the phosphorylation of STAT3. Immunostaining showed that phosphorylated STAT3 was expressed mostly in α-SMA positive cells in the peritoneal membrane induced by HG-PDF. Administration of S3I-201 prevented the progression of peritoneal fibrosis, angiogenesis, macrophage infiltration as well as the expression of HIF-1α in the peritoneal membrane induced by high glucose.ConclusionsTaken together, these findings identified a novel mechanism linking STAT3/HIF-1α signaling to peritoneal fibrosis during long-term PD treatment. It provided the first evidence that pharmacological inhibition of STAT3 signaling attenuated high glucose-mediated mesothelial cells EMT as well as peritoneal fibrosis.

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HIF-1?/GPER signaling mediates the expression of VEGF induced by hypoxia in breast cancer associated fibroblasts (CAFs).

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HIF-1α/GPER signaling mediates the expression of VEGF induced by hypoxia in breast cancer associated fibroblasts (CAFs).

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