Activation of TRPV2 and BKCa channels by the LL-37 enantiomers stimulates calcium entry and migration of cancer cells.

International audienceExpression of the antimicrobial peptide hCAP18/LL-37 is associated to malignancy in various cancer forms, stimulating cell migration and metastasis. We report that LL-37 induces migration of three cancer cell lines by activating the TRPV2 calcium-permeable channel and recruiting it to pseudopodia through activation of the PI3K/AKT pathway. Ca2+ entry through TRPV2 cooperated with a K+ efflux through the BKCa channel. In a panel of human breast tumors, the expression of TRPV2 and LL-37 was found to be positively correlated. The D-enantiomer of LL-37 showed identical effects as the L-peptide, suggesting that no binding to a specific receptor was involved. LL-37 attached to caveolae and pseudopodia membranes and decreased membrane fluidity, suggesting that a modification of the physical properties of the lipid membrane bilayer was the underlying mechanism of its effects

Efficacy and Hemotoxicity of Stealth Doxorubicin-Loaded Magnetic Nanovectors on Breast Cancer Xenografts

International audienceIn the field of oncology, research is now focused on the development of theranostic nanosystems that combine the functions of drug delivery and imaging for diagnosis/monitoring. In this context, we designed polyethylene glycol (PEG)ylated superparamagnetic iron oxide nanoparticles (SPIONs) for the delivery of doxorubicin (DOX), an antineoplastic agent. These DOX-loaded PEGylated SPIONs, or DLPS, should be useful for the delivery of DOX in vivo, as well as for magnetic drug targeting (MDT) and magnetic resonance imaging (MRI). The aim of this study was to evaluate the potential applications of DLPS in vivo as drug carrier systems for the reduction of xenograft breast tumors induced in nude mice. Prior to the animal model experiments, the main internalization pathways for the nanovectors in MDA-MB435 breast cancer cells were determined to be based on caveolae- and clathrin-mediated endocytosis. The time- and quantity-dependence of the nanoparticle uptake by the cells altered the in vitro cytotoxicity of the DLPS. The in vitro antiproliferative effect of the DLPS was dependent not only on DOX concentration, but also on the efficacy of nanoparticle internalization. Evaluation of the effect of DLPS treatment on xenograft tumors in nude mice showed that DLPS limited tumor growth in a manner comparable to that of free DOX under normal conditions of tumor growth. The application of an external magnetic field on tumors, i.e., MDT, did not improve the efficacy of the DLPS treatment. Nevertheless, the vectorization of DOX with DLPS appears to limit the hematologic side effects usually associated with DOX treatment

Human kallikrein-related peptidase 12 stimulates endothelial cell migration by remodeling the fibronectin matrix

Abstract Kallikrein-related peptidase 12 (KLK12) is a kallikrein family peptidase involved in angiogenesis – a complex biological process in which the sprouting, migration and stabilization of endothelial cells requires extracellular matrix remodeling. To characterize the molecular mechanisms associated with KLK12′s proangiogenic activity, we evaluated its ability to hydrolyze various matrix proteins. Our results show that KLK12 efficiently cleaved the human extracellular matrix proteins fibronectin and tenascin, both of which are involved in the regulation of endothelial cell adhesion and migration. For fibronectin, the major proteolytic product generated by KLK12 was a 29 kDa fragment containing the amino-terminal domain and the first five type I fibronectin-domains, which are essential for regulating fibronectin assembly. We also demonstrated that KLK12-mediated fibronectin proteolysis antagonizes fibronectin polymerization and fibronectin fibril formation by endothelial cells, leading to an increase in cell migration. Furthermore, a polyclonal antibody raised against KLK12′s proteolytic cleavage site on fibronectin prevented the KLK12-dependent inhibition of fibronectin polymerization and the KLK12-mediated pro-migratory effect on endothelial cells. Taken as a whole, our results indicate that KLK12′s proangiogenic effect is mediated through several molecular mechanisms

Murine AML12 hepatocytes allow Salmonella Typhimurium T3SS1-independent invasion and intracellular fate

International audienceNumerous studies have demonstrated the key role of the Salmonella Pathogenicity Island 1-encoded type III secretion system (T3SS1) apparatus as well as its associated effectors in the invasion and intracellular fate of Salmonella in the host cell. Several T3SS1 effectors work together to control cytoskeleton networks and induce massive membrane ruffles, allowing pathogen internalization. Salmonella resides in a vacuole whose maturation requires that the activity of T3SS1 subverts early stages of cell signaling. Recently, we identified five cell lines in which Salmonella Typhimurium enters without using its three known invasion factors: T3SS1, Rck and PagN. The present study investigated the intracellular fate of Salmonella Typhimurium in one of these models, the murine hepatocyte cell line AML12. We demonstrated that both wild-type Salmonella and T3SS1-invalidated Salmonella followed a common pathway leading to the formation of a Salmonella containing vacuole (SCV) without classical recruitment of Rho-GTPases. Maturation of the SCV continued through an acidified phase that led to Salmonella multiplication as well as the formation of a tubular network resembling Salmonella induced filaments (SIF). The fact that in the murine AML12 hepatocyte, the T3SS1 mutant induced an intracellular fate resembling to the wild-type strain highlights the fact that Salmonella Typhimurium invasion and intracellular survival can be completely independent of T3SS1

Développement de différentes méthodes de microscopie corrélative

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Supplementary Material for: Inhibition of Pathogenic Mutant SOD1 Aggregation in Cultured Motor Neuronal Cells by Prevention of Its SUMOylation on Lysine 75

<br>Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the selective death of motor neurons. Mutations in the <i>SOD1 </i>gene encoding the superoxide dismutase 1 are present in 15% of familial ALS cases and in 2% of sporadic cases. These mutations are associated with the formation of SOD1-positive aggregates. The mechanisms of aggregation remain unknown, but posttranslational modifications of SOD1 may be involved. Here, we report that NSC-34 motor neuronal cells expressing mutant SOD1 contained aggregates positive for small ubiquitin modifier-1 (SUMO-1), and in parallel a reduced level of free SUMO-1. CLEM (correlative light and electron microscopy) analysis showed nonorganized cytosolic aggregates for all mutations tested (SOD1^A4V, SOD1^V31A, and SOD1^G93C). We next show that preventing the SUMOylation of mutant SOD1 by the substitution of lysine 75, the SUMOylation site of SOD1, significantly reduces the number of motor neuronal cells with aggregates. These results support the need for further research on the SUMOylation pathways, which may be a potential therapeutic target in ALS