Implication du canal TRPM7 dans les mécanismes métastatiques de l'adénocarcinome canalaire pancréatique

L'adénocarcinome canalaire pancréatique (ACP) est le type de cancer le plus fréquent touchant le pancréas exocrine. Il est caractérisé par un phénotype métastatique et chimio-résistant pour lequel il n'existe aucun marqueur diagnostic, ni de traitement efficace. Les projections pour 2030 montrent que ce cancer pourrait devenir la deuxième cause de mortalité. Il y a un besoin urgent de mieux comprendre comment progresse l'ACP. La dissémination métastatique dépend de plusieurs mécanismes cellulaires dont l'invasion du stroma par les cellules cancéreuses. Nous avons montré récemment que le canal transmembranaire TRPM7 est surexprimé dans l'ACP et régule la migration cellulaire. Le but de ce travail est d'évaluer le rôle de TRPM7 dans l'invasion et de mettre en évidence les mécanismes moléculaires impliqués dans les cellules cancéreuses d'ACP et également dans les cellules non-cancéreuses. TRPM7 régule l'invasion basale dans les cellules cancéreuses pancréatiques via l'entrée constitutive de magnésium et la régulation de la sécrétion de MMP-2, uPA et Hsp90α. TRPM7 interagit directement avec Hsp90α et sa kinase participe à la phosphorylation des résidus sérines. De plus, l'expression de TRPM7 dans les métastases est corrélée à celle dans la tumeur primaire. Dans les cellules non cancéreuses, TRPM7 n'est pas impliqué dans l'invasion basale mais sa surexpression (par transfections de plasmides ou induite par une exposition au cadmium, un polluant probablement carcinogène) entraine la transformation des cellules vers un phénotype invasif. TRPM7 est impliqué dans la modification de l'homéostasie magnésique majoritairement, dans la modification de morphologie cellulaire et la transition épithélio-mésenchymateuse. Pour conclure, nos résultats apportent de nouvelles connaissances sur le rôle TRPM7 en tant que régulateur de l'invasion basale dans l'ACP et initiateur dans l'acquisition du phénotype invasif des cellules non-cancéreusesPancreatic ductal adenocarcinoma (PDAC) is the most common form of pancreatic cancer. It is characterized by a metastatic and chemoresistant phenotype for which there is no diagnostic marker or effective treatment. It may become the second leading cause of cancer-related death by 2030. There is an urgent need to better understand PDAC progression. Metastatic spread depends on several cellular mechanisms, including the invasion of stroma by cancer cells. We have recently shown that the transmembrane channel TRPM7 (Transient Receptor Potential Melastatin related 7) is overexpressed in PDAC and regulates cell migration. The aim of this work is to evaluate TRPM7 implication in invasion and to highlight the molecular mechanisms in PDAC and non-cancer pancreatic cells. TRPM7 channel regulates basal cell invasion, MMP-2, uPA and Hsp90α secretion in human pancreatic cancer cell lines through constitutive magnesium entry. TRPM7 interacts directly with Hsp90α and it contributes to the phosphorylation of serine residues. Magnesium could participate by activating TRPM7 kinase or by modifying Hsp90α conformation. Moreover, TRPM7 expression in metastatic lymph nodes is correlated to its expressionin primary tumor. In non-cancer cells, TRPM7 is not implicated in basal cell invasion but its overexpression (through plasmid orchronic treatment with cadmium, known as probable carcinogen pollutant) induces invasive phenotype transition. TRPM7 is mainly involved in magnesium homeostasis variation, in cellular morphology modification and mesenchymal transition. In conclusion, our results provide new insights into the key role of TRPM7 in both regulation of basal cell invasion in ACP and initiation of invasive phenotype acquisition in non-cancer epithelial cell

Formulants of glyphosate-based herbicides have more deleterious impact than glyphosate on TM4 Sertoli cells

International audienceRoundup and Glyphogan are glyphosate-based herbicides containing the same concentration of glyphosate and confidential formulants. Formulants are declared as inert diluents but some are more toxic than glyphosate, such as the family of polyethoxylated alkylamines (POEA). We tested glyphosate alone, glyphosate-based herbicide formulations and POEA on the immature mouse Sertoli cell line (TM4), at concentrations ranging from environmental to agricultural-use levels. Our results show that formulations of glyphosate-based herbicides induce TM4 mitochondrial dysfunction (like glyphosate, but to a lesser extent), disruption of cell detoxification systems, lipid droplet accumulation and mortality at sub-agricultural doses. Formulants, especially those present in Glyphogan, are more deleterious than glyphosate and thus should be considered as active principles of these pesticides. Lipid droplet accumulation after acute exposure to POEA suggests the rapid penetration and accumulation of formulants, leading to mortality after 24 h. As Sertoli cells are essential for testicular development and normal onset of spermatogenesis, disturbance of their function by glyphosate-based herbicides could contribute to disruption of reproductive function demonstrated in mammals exposed to these pesticides at a prepubertal stage of development

The Masquelet technique: Current concepts, animal models, and perspectives

International audienceBone reconstruction within a critical-sized defect remains a real challenge in orthopedic surgery. The Masquelet technique is an innovative, two-step therapeutic approach for bone reconstruction in which the placement of a poly (methylmethacrylate) spacer into the bone defect induces the neo-formation of a tissue called ``induced membrane.'' This surgical technique has many advantages and is often preferred to a vascularized bone flap or Ilizarov's technique. Although the Masquelet technique has achieved high clinical success rates since its development by Alain-Charles Masquelet in the early 2000s, very little is known about how the process works, and few animal models of membrane induction have been developed. Our successful use of this technique in the clinic and our interest in the mechanisms of tissue regeneration (notably bone regeneration) prompted us to develop a surgical model of the Masquelet technique in rats. Here, we provide a comprehensive review of the literature on animal models of membrane induction, encompassing the defect site, the surgical procedure, and the histologic and osteogenic properties of the induced membrane. We also discuss the advantages and disadvantages of those models to facilitate efforts in characterizing the complex biological mechanisms that underlie membrane induction

Interactions MUC4-canaux ioniques TRPM7 et KCa3.1 dans l’adénocarcinome pancréatique

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The Transient Receptor Potential Melastatin 7 Channel Regulates Pancreatic Cancer Cell Invasion through the Hsp90α/uPA/MMP2 pathway

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a very poor prognosis. There is an urgent need to better understand the molecular mechanisms that regulate PDAC cell aggressiveness. The transient receptor potential melastatin 7 (TRPM7) is a nonselective cationic channel that mainly conducts Ca2+ and Mg2+. TRPM7 is overexpressed in numerous malignancies including PDAC. In the present study, we used the PANC-1 and MIA PaCa-2 cell lines to specifically assess the role of TRPM7 in cell invasion and matrix metalloproteinase secretion. We show that TRPM7 regulates Mg2+ homeostasis and constitutive cation entry in both PDAC cell lines. Moreover, cell invasion is strongly reduced by TRPM7 silencing without affecting the cell viability. Conditioned media were further studied, by gel zymography, to detect matrix metalloproteinase (MMP) secretion in PDAC cells. Our results show that MMP-2, urokinase plasminogen activator (uPA), and heat-shock protein 90α (Hsp90α) secretions are significantly decreased in TRPM7-deficient PDAC cells. Moreover, TRPM7 expression in human PDAC lymph node metastasis is correlated to the channel expression in primary tumor. Taken together, our results show that TRPM7 is involved in PDAC cell invasion through regulation of Hsp90α/uPA/MMP-2 proteolytic axis, confirming that this channel could be a promising biomarker and possibly a target for PDAC metastasis therapy

The role of TRPM7 kinase-domain: Looking for new partners in pancreatic ductal adenocarcinoma.

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Cadmium exposure enhances cell migration and invasion through modulated TRPM7 channel expression

International audienceCadmium is a xenobiotic involved in neoplastic transformation. Cadmium enters the cells through divalent cation transporters including the Transient Receptor Potential Melastatin-related 7 (TRPM7) which is known to be involved in cancer cell fate. This work aimed to study the role of TRPM7 in neoplastic transformation induced by cadmium exposure in non-cancer epithelial cells. Non-cancer epithelial cells were chronically exposed to low-dose of cadmium. TRPM7 expression and function were studied by Western-Blot, Patch-Clamp and calcium and magnesium imaging. Finally, cell migration and invasion were studied by Boyden chamber assays. Chronic cadmium exposure induced TRPM7 overexpression and increased the membrane currents (P < 0.001). Cells exposed to cadmium had higher intracellular calcium and magnesium levels (P < 0.05). TRPM7 silencing restored calcium levels but strongly decreased intracellular magnesium concentration (P < 0.001). Moreover, cadmium exposure enhanced both cell migration and invasion, but TRPM7 silencing strongly decreased these features (P < 0.001). Furthermore, mammary epithelial cells exposed to cadmium became rounded and had less cell-to-cell junctions. Cadmium exposure decreased epithelial markers while the mesenchymal ones were increased. Importantly, TRPM7 silencing was able to reverse these phenotypic modifications (P < 0.05). To summarize, our data show that chronic cadmium exposure enhanced TRPM7 expression and activity in non-cancer epithelial cells. TRPM7 overexpression induced intracellular magnesium increase and stimulated cell migration and invasion. These neoplastic properties could be linked to a TRPM7-dependent epithelial-to-mesenchymal transition reprogramming in cell exposed to cadmium. These findings provide new insights into the regulation of cell fates by cadmium exposur

TRPM7 Modulates Human Pancreatic Stellate Cell Activation.

International audiencePancreatic diseases, such as pancreatitis or pancreatic ductal adenocarcinoma, are characterized by the presence of activated pancreatic stellate cells (PSCs). These cells represent key actors in the tumor stroma, as they actively participate in disease development and progression: reprograming these PSCs into a quiescent phenotype has even been proposed as a promising strategy for restoring the hallmarks of a healthy pancreas. Since TRPM7 channels have been shown to regulate hepatic stellate cells proliferation and survival, we aimed to study the role of these magnesium channels in PSC activation and proliferation. PS-1 cells (isolated from a healthy pancreas) were used as a model of healthy PSCs: quiescence or activation were induced using all-trans retinoic acid or conditioned media of pancreatic cancer cells, respectively. The role of TRPM7 was studied by RNA silencing or by pharmacological inhibition. TRPM7 expression was found to be correlated with the activation status of PS-1 cells. TRPM7 expression was able to regulate proliferation through modulation of cell cycle regulators and most importantly p53, via the PI3K/Akt pathway, in a magnesium-dependent manner. Finally, the analysis of TCGA database showed the overexpression of TRPM7 in cancer-associated fibroblasts. Taken together, we provide strong evidences that TRPM7 can be considered as a marker of activated PSCs