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Movie 4 AVI file - 879K, Time-lapse videomicroscopy of wound healing assay using GFP-ATIP3-transiently transfected D3H2LN cells

Movie 3 AVI file - 997K, Time-lapse videomicroscopy of wound healing assay using GFP-transiently transfected D3H2LN cells

Supplementary Tables XLS file - 200K, Table SI : breast tumors and normal samples data; Table SII: MTUS1 expression level in invasive breast tumors collected at Institut Gustave Roussy; Table SIII: Time-course of metastasis formation

Movie 2 AVI file - 2424K, Time-lapse videomicroscopy of wound healing assay using GFP-ATIP3-transfected D3H2LN clone (Cl3)

Movie 5 AVI file - 6439K, Time-lapse videomicroscopy of EB1-GFP comets in siRNA-silenced HeLa cells

Supplementary Information PDF file - 115K, Supplemental materials and methods, legends to Movies and supplemental references

Movie 6 AVI file - 5618K, Time-lapse videomicroscopy of EB3-GFP comets in wild type and mCherry-ATIP3 transfected MRC5 cells

Supplementary Figures PDF file - 486K, Figure S1. Low levels of ATIP3 associate with decreased overall and relapse-free survival of the patients;Figure S2. Anti-metastatic effects of ATIP3 in vivo; Figure S3. ATIP3 inhibits breast cancer cell proliferation and migration; Figure S4. ATIP3 regulates MT dynamics; Figure S5. Characterization of ATIP3 domains

Movie 1 AVI file - 2575K, Time-lapse videomicroscopy of wound healing assay using GFP-transfected D3H2LN clone

Movie 7 AVI file - 629K, Time-lapse videomicroscopy of wound healing assay in GFP-D2-transiently transfected D3H2LN cells

// Lauriane Velot 1,2,3,* , Angie Molina 1,2,3,* , Sylvie Rodrigues-Ferreira 1,2,3 , Anne Nehlig 1,2 , Benjamin Pierre Bouchet 4 , Marina Morel 3 , Ludovic Leconte 5 , Laurence Serre 6 , Isabelle Arnal 6 , Diane Braguer 7,8 , Ariel Savina 9 , Stephane Honore 7,8 and Clara Nahmias 1,2,3 1 Inserm U981, Institut Gustave Roussy Department of Molecular Medicine, Villejuif, France 2 Universite Paris-Saclay, Villejuif, France 3 CNRS UMR8104, Institut Cochin, Paris, France 4 Cell Biology, Faculty of Science, Utrecht University, Padualaan, CH Utrecht, The Netherlands 5 Cell and Tissue Imaging Core Facilty, PICT-IBiSA, CNRS UMR144 Institut Curie, Centre de Recherche, Paris, France 6 Inserm U836, Grenoble Institut des Neurosciences, Grenoble, France 7 Aix Marseille Universite, Inserm, CRO2 UMR_S 911, Marseille, France 8 APHM, Hopital Timone, Marseille, France 9 Scientific Partnerships Roche SAS, Boulogne Billancourt, France * These authors have contributed equally to this work Correspondence to: Clara Nahmias, email: // Keywords : EB1, MTUS1, protein interaction, +TIP, microtubule dynamics Received : May 07, 2015 Accepted : October 14, 2015 Published : October 20, 2015 Abstract The regulation of microtubule dynamics is critical to ensure essential cell functions. End binding protein 1 (EB1) is a master regulator of microtubule dynamics that autonomously binds an extended GTP/GDP-Pi structure at growing microtubule ends and recruits regulatory proteins at this location. However, negative regulation of EB1 association with growing microtubule ends remains poorly understood. We show here that microtubule-associated tumor suppressor ATIP3 interacts with EB1 through direct binding of a non-canonical proline-rich motif. Results indicate that ATIP3 does not localize at growing microtubule ends and that in situ ATIP3-EB1 molecular complexes are mostly detected in the cytosol. We present evidence that a minimal EB1-interacting sequence of ATIP3 is both necessary and sufficient to prevent EB1 accumulation at growing microtubule ends in living cells and that EB1-interaction is involved in reducing cell polarity. By fluorescence recovery of EB1-GFP after photobleaching, we show that ATIP3 silencing accelerates EB1 turnover at microtubule ends with no modification of EB1 diffusion in the cytosol. We propose a novel mechanism by which ATIP3-EB1 interaction indirectly reduces the kinetics of EB1 exchange on its recognition site, thereby accounting for negative regulation of microtubule dynamic instability. Our findings provide a unique example of decreased EB1 turnover at growing microtubule ends by cytosolic interaction with a tumor suppressor.

Prostate cancer (PC) is the most frequently diagnosed cancer in Canadian men and is the 3rd cause of cancer mortality. The Androgen Receptor (AR) is activated by androgens (e.g. testosterone), which leads to prostatic cell proliferation. The primary treatment for advanced PC is androgen-deprivation therapy, which is achieved via surgical or chemical castration. Nevertheless, most PC will become castration-resistant (CRPC). Although new anti-androgens (e.g. Enzalutamide) were developed to improve patients’ survival, their efficacy is still very limited and most CRPC patients will die from the disease within a few years. We postulate that by gaining insights into AR signalling networks in the context of CRPC, we could better direct patients towards the best-suited therapy and propose new therapeutic targets. To this aim, we took advantage of an innovative proteomics approach, namely proximity-labeling (BioID), to characterize global AR signalling networks in hormone-dependant LAPC4 cells. We identified 45 AR-associated proteins in non-stimulated cells, 35 of which were not previously reported. Upon androgenic stimulation, the AR signalling network increased to 320 proteins, including 278 (253 were novel) that were restricted to androgen-stimulated cells. Enzalutamide treatment resulted in a loss of 259 proteins from the network when compared to stimulated cells. As expected, this reproduced quite faithfully the status of non-stimulated LAPC4 cells. Interestingly, we identified 4 proteins in the AR network specifically after Enzalutamide treatment. These are interesting targets that may be relevant for the acquisition or the prediction of Enzalutamide resistance. Hence, they could become in time alternative therapeutic targets for CRPC treatment, to be used when Enzalutamide fails. Citation Format: Lauriane VELOT, Dominique Levesque, François-Michel Boisvert, Nicolas Bisson, Frédéric Pouliot. Proteomic identification of therapeutics targets for Enzalutamide resistance in Castration Resistant Prostate Cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 220. doi:10.1158/1538-7445.AM2017-220

Metastasis, a fatal complication of breast cancer, does not fully benefit from available therapies. In this study, we investigated whether ATIP3, the major product of 8p22 MTUS1 gene, may be a novel biomarker and therapeutic target for metastatic breast tumors. We show that ATIP3 is a prognostic marker for overall survival among patients with breast cancer. Notably, among metastatic tumors, low ATIP3 levels associate with decreased survival of the patients. By using a well-defined experimental mouse model of cancer metastasis, we show that ATIP3 expression delays the time-course of metastatic progression and limits the number and size of metastases in vivo. In functional studies, ATIP3 silencing increases breast cancer cell migration, whereas ATIP3 expression significantly reduces cell motility and directionality. We report here that ATIP3 is a potent microtubule-stabilizing protein whose depletion increases microtubule dynamics. Our data support the notion that by decreasing microtubule dynamics, ATIP3 controls the ability of microtubule tips to reach the cell cortex during migration, a mechanism that may account for reduced cancer cell motility and metastasis. Of interest, we identify a functional ATIP3 domain that associates with microtubules and recapitulates the effects of ATIP3 on microtubule dynamics, cell proliferation, and migration. Our study is a major step toward the development of new personalized treatments against metastatic breast tumors that have lost ATIP3 expression. Cancer Res; 73(9); 2905–15. ©2013 AACR.