Analysis of Transduction Pathways (ATP)

Team Publications

Year of publication 2014

Sylvain Lefort, Carine Joffre, Yann Kieffer, Anne-Marie Givel, Brigitte Bourachot, Giulia Zago, Ivan Bieche, Thierry Dubois, Didier Meseure, Anne Vincent-Salomon, Jacques Camonis, Fatima Mechta-Grigoriou (2014 Nov 27)

Inhibition of autophagy as a new means of improving chemotherapy efficiency in high-LC3B triple-negative breast cancers.

Autophagy : 2122-42 : DOI : 10.4161/15548627.2014.981788 Learn more
Summary

The triple-negative breast cancer (TN BC) subtype is the most aggressive form of invasive BC. Despite intensive efforts to improve BC treatments, patients with TN BC continue to exhibit poor survival, with half developing resistance to chemotherapy. Here we identify autophagy as a key mechanism in the progression and chemoresistance of a subset of TN tumors. We demonstrate that LC3B, a protein involved in autophagosome formation, is a reliable marker of poor prognosis in TN BC, validating this prognostic value at both the mRNA and protein levels in several independent cohorts. We also show that LC3B has no prognostic value for other BC subtypes (Luminal or HER2 BC), thus revealing a specific impact of autophagy on TN tumors. Autophagy is essential for the proliferative and invasive properties in 3D of TN BC cells characterized by high LC3B levels. Interestingly, the activity of the transcriptional co-activator YAP1 (Yes-associated protein 1) is regulated by the autophagy process and we identify YAP1 as a new actor in the autophagy-dependent proliferative and invasive properties of high-LC3B TN BC. Finally, inhibiting autophagy by silencing ATG5 or ATG7 significantly impaired high-LC3B TN tumor growth in vivo. Moreover, using a patient-derived TN tumor transplanted into mice, we show that an autophagy inhibitor, chloroquine, potentiates the effects of chemotherapeutic agents. Overall, our data identify LC3B as a new prognostic marker for TN BC and the inhibition of autophagy as a promising therapeutic strategy for TN BC patients.

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Perla El-Hage, Ambre Petitalot, Anne-Hélène Monsoro-Burq, Frédérique Maczkowiak, Keltouma Driouch, Etienne Formstecher, Jacques Camonis, Michèle Sabbah, Ivan Bièche, Rosette Lidereau, François Lallemand (2014 Apr 2)

The Tumor-Suppressor WWOX and HDAC3 Inhibit the Transcriptional Activity of the β-Catenin Coactivator BCL9-2 in Breast Cancer Cells.

Molecular cancer research : MCR : 902-12 : DOI : 10.1158/1541-7786.MCR-14-0180 Learn more
Summary

The WW domain containing oxidoreductase (WWOX) has recently been shown to inhibit of the Wnt/β-catenin pathway by preventing the nuclear import of disheveled 2 (DVL2) in human breast cancer cells. Here, it is revealed that WWOX also interacts with the BCL9-2, a cofactor of the Wnt/β-catenin pathway, to enhance the activity of the β-catenin-TCF/LEF (T-cell factor/lymphoid enhancer factors family) transcription factor complexes. By using both a luciferase assay in MCF-7 cells and a Xenopus secondary axis induction assay, it was demonstrated that WWOX inhibits the BCL9-2 function in Wnt/β-catenin signaling. WWOX does not affect the BCL9-2-β-catenin association and colocalizes with BCL9-2 and β-catenin in the nucleus of the MCF-7 cells. Moreover, WWOX inhibits the β-catenin-TCF1 interaction. Further examination found that HDAC3 associates with BCL9-2, enhances the inhibitory effect of WWOX on BCL9-2 transcriptional activity, and promotes the WWOX-BCL9-2 interaction, independent of its deacetylase activity. However, WWOX does not influence the HDAC3-BCL9-2 interaction. Altogether, these results strongly indicate that nuclear WWOX interacts with BCL9-2 associated with β-catenin only when BCL9-2 is in complex with HDAC3 and inhibits its transcriptional activity, in part, by inhibiting the β-catenin-TCF1 interaction. The promotion of the WWOX-BCL9-2 interaction by HDAC3, independent of its deacetylase activity, represents a new mechanism by which this HDAC inhibits transcription.

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Year of publication 2013

Sardar Faisal Mahmood, Nadège Gruel, Elodie Chapeaublanc, Aurianne Lescure, Thouis Jones, Fabien Reyal, Anne Vincent-Salomon, Virginie Raynal, Gaëlle Pierron, Franck Perez, Jacques Camonis, Elaine Del Nery, Olivier Delattre, François Radvanyi, Isabelle Bernard-Pierrot (2013 Oct 22)

A siRNA screen identifies RAD21, EIF3H, CHRAC1 and TANC2 as driver genes within the 8q23, 8q24.3 and 17q23 amplicons in breast cancer with effects on cell growth, survival and transformation.

Carcinogenesis : 670-82 : DOI : 10.1093/carcin/bgt351 Learn more
Summary

RNA interference has boosted the field of functional genomics, by making it possible to carry out ‘loss-of-function’ screens in cultured cells. Here, we performed a small interfering RNA screening, in three breast cancer cell lines, for 101 candidate driver genes overexpressed in amplified breast tumors and belonging to eight amplicons on chromosomes 8q and 17q, investigating their role in cell survival/proliferation. This screening identified eight driver genes that were amplified, overexpressed and critical for breast tumor cell proliferation or survival. They included the well-described oncogenic driver genes for the 17q12 amplicon, ERBB2 and GRB7. Four of six other candidate driver genes-RAD21 and EIF3H, both on chromosome 8q23, CHRAC1 on chromosome 8q24.3 and TANC2 on chromosome 17q23-were confirmed to be driver genes regulating the proliferation/survival of clonogenic breast cancer cells presenting an amplification of the corresponding region. Indeed, knockdown of the expression of these genes decreased cell viability, through both cell cycle arrest and apoptosis induction, and inhibited the formation of colonies in anchorage-independent conditions, in soft agar. Strategies for inhibiting the expression of these genes or the function of the proteins they encode are therefore of potential value for the treatment of breast cancers presenting amplifications of the corresponding genomic region.

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Séverine Affeldt, Param Priya Singh, Ilaria Cascone, Rasim Selimoglu, Jacques Camonis, Hervé Isambert (2013 Apr 26)

[Evolution and cancer: expansion of dangerous gene repertoire by whole genome duplications].

Médecine sciences : M/S : 358-61 : DOI : 10.1051/medsci/2013294008 Learn more
Summary

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Year of publication 2010

Contreras V., Urien C., Guiton R., Alexandre Y., Vu Manh T.P., Andrieu T., Crozat K., Jouneau L., Bertho N., Epardaud M., Hope J., Savina A., Amigorena S., Bonneau M., Dalod M., Schwartz-Cornil I. (2010 Sep 15)

Existence of CD8α-like dendritic cells with a conserved functional specialization and a common molecular signature in distant mammalian species.

Journal of immunology (Baltimore, Md. : 1950) : 185 : 3313-25 Learn more
Summary

The mouse lymphoid organ-resident CD8alpha(+) dendritic cell (DC) subset is specialized in Ag presentation to CD8(+) T cells. Recent evidence shows that mouse nonlymphoid tissue CD103(+) DCs and human blood DC Ag 3(+) DCs share similarities with CD8alpha(+) DCs. We address here whether the organization of DC subsets is conserved across mammals in terms of gene expression signatures, phenotypic characteristics, and functional specialization, independently of the tissue of origin. We study the DC subsets that migrate from the skin in the ovine species that, like all domestic animals, belongs to the Laurasiatheria, a distinct phylogenetic clade from the supraprimates (human/mouse). We demonstrate that the minor sheep CD26(+) skin lymph DC subset shares significant transcriptomic similarities with mouse CD8alpha(+) and human blood DC Ag 3(+) DCs. This allowed the identification of a common set of phenotypic characteristics for CD8alpha-like DCs in the three mammalian species (i.e., SIRP(lo), CADM1(hi), CLEC9A(hi), CD205(hi), XCR1(hi)). Compared to CD26(-) DCs, the sheep CD26(+) DCs show 1) potent stimulation of allogeneic naive CD8(+) T cells with high selective induction of the Ifngamma and Il22 genes; 2) dominant efficacy in activating specific CD8(+) T cells against exogenous soluble Ag; and 3) selective expression of functional pathways associated with high capacity for Ag cross-presentation. Our results unravel a unifying definition of the CD8alpha(+)-like DCs across mammalian species and identify molecular candidates that could be used for the design of vaccines applying to mammals in general.

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Maria Carla Parrini, Amel Sadou-Dubourgnoux, Kazuhiro Aoki, Katsuyuki Kunida, Marco Biondini, Anastassia Hatzoglou, Patrick Poullet, Etienne Formstecher, Charles Yeaman, Michiyuki Matsuda, Carine Rossé, Jacques Camonis (2010 May 14)

SH3BP1, an exocyst-associated RhoGAP, inactivates Rac1 at the front to drive cell motility.

Molecular cell : 650-61 : DOI : 10.1016/j.molcel.2011.03.032 Learn more
Summary

The coordination of the several pathways involved in cell motility is poorly understood. Here, we identify SH3BP1, belonging to the RhoGAP family, as a partner of the exocyst complex and establish a physical and functional link between two motility-driving pathways, the Ral/exocyst and Rac signaling pathways. We show that SH3BP1 localizes together with the exocyst to the leading edge of motile cells and that SH3BP1 regulates cell migration via its GAP activity upon Rac1. SH3BP1 loss of function induces abnormally high Rac1 activity at the front, as visualized by in vivo biosensors, and disorganized and instable protrusions, as revealed by cell morphodynamics analysis. Consistently, constitutively active Rac1 mimics the phenotype of SH3BP1 depletion: slow migration and aberrant cell morphodynamics. Our finding that SH3BP1 downregulates Rac1 at the motile-cell front indicates that Rac1 inactivation in this location, as well as its activation by GEF proteins, is a fundamental requirement for cell motility.

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Year of publication 2009

Carine Rosse, Etienne Formstecher, Katrina Boeckeler, Yingming Zhao, Joachim Kremerskothen, Michael D White, Jacques H Camonis, Peter J Parker (2009 May 22)

An aPKC-exocyst complex controls paxillin phosphorylation and migration through localised JNK1 activation.

PLoS biology : e1000235 : DOI : 10.1371/journal.pbio.1000235 Learn more
Summary

Atypical protein kinase C (aPKC) isoforms have been implicated in cell polarisation and migration through association with Cdc42 and Par6. In distinct migratory models, the Exocyst complex has been shown to be involved in secretory events and migration. By RNA interference (RNAi) we show that the polarised delivery of the Exocyst to the leading edge of migrating NRK cells is dependent upon aPKCs. Reciprocally we demonstrate that aPKC localisation at the leading edge is dependent upon the Exocyst. The basis of this inter-dependence derives from two-hybrid, mass spectrometry, and co-immunoprecipitation studies, which demonstrate the existence of an aPKC-Exocyst interaction mediated by Kibra. Using RNAi and small molecule inhibitors, the aPKCs, Kibra, and the Exocyst are shown to be required for NRK cell migration and it is further demonstrated that they are necessary for the localized activation of JNK at the leading edge. The migration associated control of JNK by aPKCs determines JNK phosphorylation of the plasma membrane substrate Paxillin, but not the phosphorylation of the nuclear JNK substrate, c-jun. This plasma membrane localized JNK cascade serves to control the stability of focal adhesion complexes, regulating migration. The study integrates the polarising behaviour of aPKCs with the pro-migratory properties of the Exocyst complex, defining a higher order complex associated with the localised activation of JNK at the leading edge of migrating cells that determines migration rate.

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Year of publication 2006

Maria Balakireva, Carine Rossé, Johanna Langevin, Yu-chen Chien, Michel Gho, Geneviève Gonzy-Treboul, Stéphanie Voegeling-Lemaire, Sandra Aresta, Jean-Antoine Lepesant, Yohanns Bellaiche, Michael White, Jacques Camonis (2006 Sep 25)

The Ral/exocyst effector complex counters c-Jun N-terminal kinase-dependent apoptosis in Drosophila melanogaster.

Molecular and cellular biology : 8953-63 Learn more
Summary

Ral GTPase activity is a crucial cell-autonomous factor supporting tumor initiation and progression. To decipher pathways impacted by Ral, we have generated null and hypomorph alleles of the Drosophila melanogaster Ral gene. Ral null animals were not viable. Reduced Ral expression in cells of the sensory organ lineage had no effect on cell division but led to postmitotic cell-specific apoptosis. Genetic epistasis and immunofluorescence in differentiating sensory organs suggested that Ral activity suppresses c-Jun N-terminal kinase (JNK) activation and induces p38 mitogen-activated protein (MAP) kinase activation. HPK1/GCK-like kinase (HGK), a MAP kinase kinase kinase kinase that can drive JNK activation, was found as an exocyst-associated protein in vivo. The exocyst is a Ral effector, and the epistasis between mutants of Ral and of msn, the fly ortholog of HGK, suggest the functional relevance of an exocyst/HGK interaction. Genetic analysis also showed that the exocyst is required for the execution of Ral function in apoptosis. We conclude that in Drosophila Ral counters apoptotic programs to support cell fate determination by acting as a negative regulator of JNK activity and a positive activator of p38 MAP kinase. We propose that the exocyst complex is Ral executioner in the JNK pathway and that a cascade from Ral to the exocyst to HGK would be a molecular basis of Ral action on JNK.

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Yuchen Chien, Sungchan Kim, Ron Bumeister, Yueh-Ming Loo, Sung Won Kwon, Cynthia L Johnson, Mirey G Balakireva, Yves Romeo, Levy Kopelovich, Michael Gale, Charles Yeaman, Jacques H Camonis, Yingming Zhao, Michael A White (2006 Feb 21)

RalB GTPase-mediated activation of the IkappaB family kinase TBK1 couples innate immune signaling to tumor cell survival.

Cell : 157-70 Learn more
Summary

The monomeric RalGTPases, RalA and RalB are recognized as components of a regulatory framework supporting tumorigenic transformation. Specifically, RalB is required to suppress apoptotic checkpoint activation, the mechanistic basis of which is unknown. Reported effector proteins of RalB include the Sec5 component of the exocyst, an octameric protein complex implicated in tethering of vesicles to membranes. Surprisingly, we find that the RalB/Sec5 effector complex directly recruits and activates the atypical IkappaB kinase family member TBK1. In cancer cells, constitutive engagement of this pathway, via chronic RalB activation, restricts initiation of apoptotic programs typically engaged in the context of oncogenic stress. Although dispensable for survival in a nontumorigenic context, this pathway helps mount an innate immune response to virus exposure. These observations define the mechanistic contribution of RalGTPases to cancer cell survival and reveal the RalB/Sec5 effector complex as a component of TBK1-dependent innate immune signaling.

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