KCa/Ca channel complexes sensitive to ether-lipids : regulation of calcium signaling in cancer cells migration

La formation de métastases est la cause majeure des décès par cancer. Le développement de métastases est consécutif à une série d‟événements complexes tels que la migration, l‟invasion et la prolifération cellulaire. Le canal potassique SK3 (membre de la famille des SKCa) régule la migration des cellules cancéreuses du sein et favorise le développement de métastases osseuses. Le but du projet était d‟identifier et de caractériser les voies d‟entrées calciques associées à la migration cellulaire dépendante du canal SK3 dans différents cancers (sein, colon et prostate). Nous avons pu mettre en évidence que les canaux Ca2+qui étaient associés au canal SK3 variaient en fonction du cancer et régulaient la migration cellulaire dépendante du canal SK3. De plus, nous avons montré que la localisation de ces complexes KCa/Ca2+ dans les radeaux lipidiques était importante pour leur régulation et leur fonction. Ainsi, la délocalisation de ces complexes hors des radeaux lipidiques par des alkyl-phospholipides est un moyen permettant de moduler la migration des cellules exprimant le canal SK3 et le développement de métastases.In most cases of cancer, metastasis and not the primary tumor per se is the main cause of mortality. To establish secondary growth in distant organs cancer cells must develop an enhanced propensity to migrate. The key objective of this thesis proposes that some actors of Ca2+ signaling (Orai, and TRPC, STIM) coupled to SK3 channel would form complexes that play a critical role in cell migration of various cancers (breast, colon and prostate). Furthermore we showed that the localization of these channels complexes in lipid-rafts is essential to their regulation and function. Thus, the delocalization of these complexes of lipid-raft outside by alkyl-phospholipids could be a new way to modulate the SK3/Ca2+ dependent cell migration and metastasis development

micro-ARN et cancer colorectal

International audienceRésumé : Les micro-ARN (miR) sont de petits ARN simple brin. Leur rôle est de réguler la traduction d'ARN messager cible. Ils impactent ainsi le fonctionnement global de notre organisme. Leur dérégulation est impliquée dans un grand nombre de mécanismes pathologiques, notamment dans l'initiation et la progression tumorales colorectales. Il est possible de détecter les fluctuations d'expression des miR dans les tissus digestifs, le sang et les selles. Certains miR ont été identifiés comme des potentiels biomarqueurs diagnostiques et pronostiques du cancer colorectal (CCR). Leurs dérégulations participent également aux mécanismes de résistance à certains médicaments anti-tumoraux. La mesure du niveau d'expression de miR est une piste pour la recherche de biomarqueurs prédictifs de l'efficacité des traitements couramment prescrits dans le CCR. Ils sont également des cibles thérapeutiques potentielles car l'induction pharmacologique de la sur-ou sous-expression de certains miR pourrait être utilisée afin de modifier les caractéristiques des tumeurs et servir de base pour de nouvelles thérapies en oncologie. Les miR représentent des éléments clefs du développement du CCR avec des perspectives d'applications prometteuses et innovantes en pratique clinique.

DiGalactosyl-Glycero-Ether Lipid: synthetic approaches and evaluation as SK3 channel inhibitor.

International audienceThe recent discoveries of the involvement of SK3 channel in some cell motility mechanisms occurring in cancer disease have opened up the way to the synthesis of inhibitors that could reduce metastasis formation. On the basis of our recent previous works showing that both lactose-glycero-ether lipid () and some phosphate analogues () were efficient compounds to modulate SK3 channel activity, the present study, which found its inspiration in the structure of the natural glycolipid DiGalactosylDiacylGlycerol (DGDG), reports the incorporation of a digalactosyl moiety (α-galactopyranosyl-(1→6)-β-galactopyranosyl-) as the polar head of a glycero ether lipid. For the construction of the digalactosyl fragment, two synthetic approaches were compared. The standard strategy which is based on the use of the benzyl protecting group to produce 1→6 disaccharide unit, was compared with a second method that made use of the trimethylsilyl moiety as a protecting group. This second strategy, which is applied for the first time to the synthesis of (1→6)-disaccharide unit, presents a net advantage in terms of efficacy (better global yield) and cost. Finally, compound , which is characterized by a (1→6) DiGalactosyl unit (DG) as the polar head of the amphiphilic structure, was tested as a modulator of the SK3 channel activity. Patch-clamp experiments have shown that compound reduced SK3 currents (-28.2 ± 2.0% at 5 μM) and cell migration assays performed at 300 nM have shown a reduction of cell migration (SK3 + HEK293T) by 19.6 ± 2.7%

SK3 Gene Polymorphism Is Associated with Taxane Neurotoxicity and Cell Calcium Homeostasis

International audiencePurpose: Taxane-induced peripheral neuropathy is a common side effect induced by anticancer agents, and no drug capable of preventing its occurrence or ameliorating its long-term course has been identified. The physiology of taxane neuropathy is not clear, and diverse mechanisms have been suggested, with ion channels regulating Ca2+ homeostasis appearing good candidates. The calcium-activated potassium channel SK3 is encoded by the KCNN3 gene, which is characterized by a length polymorphism due to variable number of CAG repeats.Experimental Design: To study the influence of the polymorphism of CAG motif repeat of KCNN3 on the development of taxane-induced neuropathy, we evaluated 176 patients treated with taxanes for breast cancer. In parallel, we measured Ca2+ entry using Fura2-AM dye in HEK cells expressing short versus long CAG alleles of KCNN3 Results: In the current study, we report that in the presence of docetaxel, Ca2+ entry was significantly increased in cells expressing short versus long CAG alleles of SK3 and that a SK3-lipid blocker inhibits this effect. We found that patients carrying a short KCNN3 allele exhibited significantly increased incidence of taxane neuropathy compared with those carrying longer alleles.Conclusions: The clinical implication of these findings is that KCNN3 polymorphism may increase patient susceptibility to taxane neurotoxicity and that the use of SK3 blockers during taxanes' administration may represent an interesting approach for the prevention of this neurotoxicity. Clin Cancer Res; 24(21); 5313-20. ©2018 AACR

Cross-talk between N-terminal and C-terminal domains in stromal interaction molecule 2 (STIM2) determines enhanced STIM2 sensitivity

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A calcium/cAMP signaling loop at the ORAI1 mouth drives channel inactivation to shape NFAT induction

ORAI1 constitutes the store-operated Ca2+ release-activated Ca2+ (CRAC) channel, but how this channel is turned off through Ca2+-dependent inactivation (CDI) remained unclear. Here the authors identify a spatially-restricted Ca2+/cAMP signaling crosstalk critical for mediating CDI which in turn regulates cellular Ca2+ signals and NFAT activation

Recombinant Intrabodies as Molecular Tools and Potential Therapeutics for Amyotrophic Lateral Sclerosis

This is the final version of the article, which has been published in final form at : http://www.lestudium-ias.com/content/recombinant-intrabodies-molecular-tools-and-potential-therapeutics-amyotrophic-lateralAmyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that has no diagnostic marker, prognosis, nor an effective treatment. Numerous physiopathological mechanisms have been described for this disease, such as glutamatergic excitotoxicity, oxidative stress, and the accumulation of protein aggregates in cells of the central nervous system, in particular the aggregation of cytoplasmic TDP-43.Our aim was targeting the protein aggregates containing TDP-43 through fragments of antibodies synthesized by the cell, termed intrabodies. In order to determine the most relevant criteria to test the protective effects of the intrabodies, we searched for different toxicity markers associated with TDP-43aggregates. During the fellowship, the fellow participated of 2 publications of the host laboratory in this field. Besides, at the end of the fellowship, the host Scientist and the Le Studium fellow organized a conference about iPS cells, a powerful tool to model in vitro neurodegenerative diseases such as ALS. In addition, the fellow generated preliminary results showing that TDP-43 overexpression in HEK 293 cells does not affect mitochondrial respiration, but causes an increase in cytoplasmic calcium levels, while impairs the mitochondrial capacity to buffer the excessive cytoplasmic calcium. Moreover, preliminary patch clamp data showed alterations in spontaneous currents in primary hippocampal and motor neurons overexpressing TDP-43. If these results are further confirmed, calcium signaling and spontaneous currents could be used as parameters to measure the efficacy of anti-TDP-43 intrabodies

Mitochondria control store‐operated Ca 2+ entry through Na + and redox signals

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