Equipe Labellisee La Ligue

La Rochelle, France

Equipe Labellisee La Ligue

La Rochelle, France
Time filter
Source Type

Chapat C.,University of Lyon | Chapat C.,French Institute of Health and Medical Research | Chapat C.,Equipe Labellisee la Ligue | Kolytcheff C.,University of Lyon | And 17 more authors.
EMBO Journal | Year: 2013

Stringent regulation of the interferon (IFN) signalling pathway is essential for maintaining the immune response to pathogens and tumours. The transcription factor STAT1 is a crucial mediator of this response. Here, we show that hCAF1/CNOT7 regulates class I and II IFN pathways at different crucial steps. In resting cells, hCAF1 can control STAT1 trafficking by interacting with the latent form of STAT1 in the cytoplasm. IFN treatment induces STAT1 release, suggesting that hCAF1 may shield cytoplasmic STAT1 from undesirable stimulation. Consistently, hCAF1 silencing enhances STAT1 basal promoter occupancy associated with increased expression of a subset of STAT1-regulated genes. Consequently, hCAF1 knockdown cells exhibit an increased protection against viral infection and reduced viral replication. Furthermore, hCAF1 participates in the extinction of the IFN signal, through its deadenylase activity, by speeding up the degradation of some STAT1-regulated mRNAs. Since abnormal and unbalanced JAK/STAT activation is associated with immune disorders and cancer, hCAF1 could play a major role in innate immunity and oncogenesis, contributing to tumour escape. © 2013 European Molecular Biology Organization.

Delfortrie S.,French National Center for Scientific Research | Delfortrie S.,University of Lille Nord de France | Delfortrie S.,Institute Pasteur Of Lille | Delfortrie S.,Equipe Labellisee la Ligue | And 39 more authors.
Cancer Research | Year: 2011

Downregulating the leukocyte adhesion molecules expressed by endothelial cells that line tumor blood vessels can limit the entry of immune effector cells into the tumor mass, thereby contributing to tumoral immune escape. Egfl7 (also known as VE-statin) is a secreted protein specifically expressed by endothelial cells in normal tissues and by cancer cells in various human tumors. High levels of Egfl7 correlate with higher tumor grade and poorer prognosis. Here we show that expression of Egfl7 in breast and lung carcinoma cells accelerates tumor growth and metastasis in immunocompetent mice but not in immunodeficient mice. Tumors expressing Egfl7 were infiltrated relatively poorly by immune cells and were characterized by reduced levels of immunostimulatory cytokines [IFN-γ, interleukin-12 (IL-12)] and fewer endothelial adhesion molecules [intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1)]. In vitro studies revealed that Egfl7 inhibited the expression of leukocyte adhesion molecules by endothelial cells, preventing lymphocyte adhesion. In contrast, Egfl7 did not exert any effects on immune cell activation. Human breast cancer lesions expressing high levels of Egfl7 also expressed less ICAM-1 and VCAM-1 in their blood vessels, also indicating an inverse correlation between expression levels of Egfl7 and IFN-γ. Thus, Egfl7 expression in tumors promotes tumor progression by reducing the expression of endothelial molecules that mediate immune cell infiltration. Our findings highlight a novel mechanism through which tumors escape immune control. ©2011 AACR.

Poulard C.,University of Lyon | Poulard C.,French Institute of Health and Medical Research | Poulard C.,French National Center for Scientific Research | Poulard C.,Center Leon Berard | And 25 more authors.
EMBO Molecular Medicine | Year: 2012

Oestrogen receptors can mediate rapid activation of cytoplasmic signalling cascades by recruiting Src and PI3K. However, the involvement of this pathway in breast cancer remains poorly defined. We have previously shown that methylation of ERα is required for the formation of the ERα/Src/PI3K complex and that ERα is hypermethylated in a subset of breast cancers. Here, we used Proximity Ligation Assay to demonstrate that this complex is present in the cytoplasm of breast cancer cell lines as well as formalin-fixed, paraffin-embedded tumours. Of particular interest, the analysis of 175 breast tumours showed that overexpression of this complex in a subset of breast tumours correlates to the activation of the downstream effector Akt. Survival analysis revealed that high expression of this complex is an independent marker of poor prognosis and associated with reduced disease-free survival. Our data introduces the new concept that the rapid oestrogen pathway is operative in vivo. It also provides a rationale for patient stratification defined by the activation of this pathway and the identification of target therapies. © 2012 The Authors.

Bouchekioua-Bouzaghou K.,University of Lyon | Bouchekioua-Bouzaghou K.,French Institute of Health and Medical Research | Bouchekioua-Bouzaghou K.,French National Center for Scientific Research | Bouchekioua-Bouzaghou K.,Equipe Labellisee la Ligue | And 28 more authors.
International Journal of Cancer | Year: 2014

Although the presence of nuclear estrogen receptor is widely used to guide breast cancer therapy, less attention has been paid to the receptor cytoplasmic signaling. Recently, we have shown that this pathway is operative in vivo and is activated in aggressive tumors representing a new potential target for breast cancer therapy. Here, we identified LKB1 as a partner of ERα and we explored its potential role in estrogen nongenomic signaling. The associations between LKB1 expression and the actors of this pathway, namely the methylated form of ERα (metERα), Src and PI3K, have been analyzed both in cultured cells and in 154 primary breast tumor samples. We found that LKB1 is a component of the cytoplasmic signaling complex in breast cell lines as well as in primary breast tumors. Moreover, an inverse correlation between the localization of LKB1 in nuclear and cytoplasmic compartments is observed. Importantly, high expression of cytoplasmic LKB1 is an independent marker of poor prognosis, associated with reduced overall survival (OS) and disease free survival (DFS). Conversely, the presence of nuclear LKB1 associates with increased OS and DFS. In conclusion, our results highlight that LKB1 expression in breast cancer appears to have opposite effects depending on its subcellular localization and may be used as a new prognostic biomarker. What's new? A methylated form of ER-α (metERα) is known to be involved in a signal-transduction pathway that is activated in aggressive breast tumors. In this study, the authors found that a protein kinase called LKB1, which usually acts as a tumor suppressor, is involved in this same oncogenic pathway. They also found that high levels of expression of cytoplasmic LKB1 is an independent marker of poor prognosis, while the presence of LKB1 in the nucleus is associated with increased survival. LKB1 may therefore serve as a useful prognostic biomarker in breast cancer. © 2014 UICC.

Poulard C.,University of Lyon | Poulard C.,French Institute of Health and Medical Research | Poulard C.,French National Center for Scientific Research | Poulard C.,Equipe Labellisee la Ligue | And 13 more authors.
PLoS ONE | Year: 2014

ERα functions are tightly controlled by numerous post-translational modifications including arginine methylation, which is required to mediate the extranuclear functions of the receptor. We report that upon oestrogenic stimulation, JMJD6, the only arginine demethylase described so far, interacts with and regulates methylated ERα (metERα) function. Moreover, by combining the silencing of JMJD6 with demethylation assays, we show that metERα is a new substrate for JMJD6. We propose that the demethylase activity of JMJD6 is a decisive regulator of the rapid physiological responses to oestrogen. ©2014 Poulard et al.

Loading Equipe Labellisee La Ligue collaborators
Loading Equipe Labellisee La Ligue collaborators