Hibernation is an exceptional physiological response to a hostile environment, characterized by a seasonal period of torpor cycles involving dramatic reductions of body temperature and metabolism, and arousal back to normothermia. As the mechanisms regulating hibernation are still poorly understood, here we analysed the expression of genes involved in energy homeostasis, torpor regulation, and daily or seasonal timing using digital droplet PCR in various central and peripheral tissues sampled at different stages of torpor/arousal cycles in the European hamster. During torpor, the hypothalamus exhibited strongly down-regulated gene expression, suggesting that hypothalamic functions were reduced during this period of low metabolic activity. During both torpor and arousal, many structures (notably the brown adipose tissue) exhibited altered expression of deiodinases, potentially leading to reduced tissular triiodothyronine availability. During the arousal phase, all analysed tissues showed increased expression of the core clock genes Per1 and Per2. Overall, our data indicated that the hypothalamus and brown adipose tissue were the tissues most affected during the torpor/arousal cycle, and that clock genes may play critical roles in resetting the body’s clocks at the beginning of the active period.

L’avènement de la biologie moléculaire et l’achèvement du séquençage du génome humain ont conduit l’industrie pharmaceutique à progressivement implémenter des approches dites cible-centriques pour identifier les candidats médicaments. Cependant, la faible productivité de la recherche et du développement en ce début de millénaire, combinée aux évolutions technologiques dans des domaines tels que l’ingénierie cellulaire, le criblage à haut contenu, la robotique, l’analyse d’images et l’intelligence artificielle, ont nourri un fort regain d’intérêt pour les approches phénotypiques. De plus en plus fréquemment, les approches cible-centriques et phénotypiques sont considérées de façon complémentaire, positionnant ainsi les techniques de déconvolution de cible sur le chemin critique de la découverte et du développement de médicaments. Cette revue analyse l’évolution des approches cible-centriques versus phénotypiques, en se focalisant plus particulièrement sur le criblage à haut contenu et les différentes techniques de déconvolution de cible aujourd’hui disponibles.

<p><strong>Background:</strong> Triple-negative breast cancer (TNBC) is a heterogeneous disease defined by ER-, PR- and HER2-negative phenotype and in most cases, a relatively aggressive clinical behaviour. The lack of specific targeted therapies and low efficiency of currently available chemotherapies spurred several clinical trials in the last few years. Despite encouraging results, TNBC still remains a major unmet medical need that prompted us to explore the role of 863 epigenetic modulators in TNBC cell survival.</p><p><strong>Methods:</strong> A comprehensive siRNA library was screened to explore the role of known epigenetic modulators in TNBC cell viability and growth. The knock-down effect was evaluated for 863 epigenetic genes using 4 siRNAs/gene in two TNBC and a non-TNBC cell lines using ATP-based luminescence and nuclei count image-based assays. Considering siRNA off-target effects, four analysis methods including a classical threshold-based analysis and three ranking methods were applied to determine on-target hits for each screen readout. Hit genes common to both phenotypic readouts highlighted strong epigenetic players involved in TNBC cell survival.</p><p><strong>Results:</strong> Overall, knock-down of many epigenetic modulator genes mitigates cell survival in TNBC and a non-TNBC cell lines depicted from both phenotypic readouts. Interestingly, ranking-based analysis confirmed hit genes identified in threshold-based analysis and also revealed additional hits enabling us to confirm CDK1 and KMT5A as important regulators in TNBC cell viability and growth. Surprisingly, CHAF1A appeared as a new candidate gene involved in TNBC cell survival.</p><p><strong>Conclusions:</strong> Taken together, siRNA epigenetic screening results identified CHAF1A as a novel regulator of TNBC cell survival.</p>

Among Breast Cancer (BC) classification, Triple-Negative (TN) form is the most aggressive, lacking efficient and specific treatment. Our project aims at investigating the possibility to convert TNBC tumor cell lines in Estrogen Receptor (ER), Progesterone Receptor (PR) and/or Human Epidermal growth factor Receptor 2 (HER2)-positive cells using various modalities (siRNA, CRISPR-Cas9, small molecules). Our approach consists in optimizing a multi-parametric High-Content Screening (HCS) relying on phenotypic read-outs such as expression of TNBC positive and negative markers, cell behavior and viability. This poster will present our initial results, validation and future plans. This thesis project fits within a context of drug discovery, innovation, comparison of technologies and understanding of key biological processes and pathways, carried out in partnership between Servier Research Institute and Institut Curie. Citation Format: Albane Gaudeau, Véronique Lamamy, Anne-Laure Jaskowiak, Xavier Scerri, Benjamin Chanrion, Thierry Dorval, Elaine Del Nery, Franck Perez, Jacques Camonis, Jean-Philippe Stéphan. Investigation of triple-negative breast cancer tumor conversion through high-content screening approaches [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1487.