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Bone metastasis is the major deleterious event in prostate cancer (PCa). TMPRSS2-ERG fusion is one of the most common chromosomic rearrangements in PCa. However, its implication in bone metastasis development is still unclear. Since bone metastasis starts with the tropism of cancer cells to bone through specific migratory and invasive processes involving osteomimetic capabilities, it is crucial to better our understanding of the influence of TMPRSS2-ERG expression in the mechanisms underlying the bone tropism properties of PCa cells. We developed bioluminescent cell lines expressing the TMPRSS2-ERG fusion in order to assess its role in tumor growth and bone metastasis appearance in a mouse model. First, we showed that the TMPRSS2-ERG fusion increases cell migration and subcutaneous tumor size. Second, using intracardiac injection experiments in mice, we showed that the expression of TMPRSS2-ERG fusion increases the number of metastases in bone. Moreover, TMPRSS2-ERG affects the pattern of metastatic spread by increasing the incidence of tumors in hind limbs and spine, which are two of the most frequent sites of human PCa metastases. Finally, transcriptome analysis highlighted a series of genes regulated by the fusion and involved in the metastatic process. Altogether, our work indicates that TMPRSS2-ERG increases bone tropism of PCa cells and metastasis development., info:eu-repo/semantics/published

Clostridium difficile is the primary cause of nosocomial diarrhea and pseudomembranous colitis. It produces dormant spores, which serve as an infectious vehicle responsible for transmission of the disease and persistence of the organism in the environment. In Bacillus subtilis, the sin locus coding SinR (113 aa) and SinI (57 aa) is responsible for sporulation inhibition. In B. subtilis, SinR mainly acts as a repressor of its target genes to control sporulation, biofilm formation, and autolysis. SinI is an inhibitor of SinR, so their interaction determines whether SinR can inhibit its target gene expression. The C. difficile genome carries two sinR homologs in the operon that we named sinR and sinR’, coding for SinR (112 aa) and SinR’ (105 aa), respectively. In this study, we constructed and characterized sin locus mutants in two different C. difficile strains R20291 and JIR8094, to decipher the locus’s role in C. difficile physiology. Transcriptome analysis of the sinRR’ mutants revealed their pleiotropic roles in controlling several pathways including sporulation, toxin production, and motility in C. difficile. Through various genetic and biochemical experiments, we have shown that SinR can regulate transcription of key regulators in these pathways, which includes sigD, spo0A, and codY. We have found that SinR’ acts as an antagonist to SinR by blocking its repressor activity. Using a hamster model, we have also demonstrated that the sin locus is needed for successful C. difficile infection. This study reveals the sin locus as a central link that connects the gene regulatory networks of sporulation, toxin production, and motility; three key pathways that are important for C. difficile pathogenesis., Author summary In Bacillus subtilis, sporulation, competence and biofilm formation are regulated by a pleiotropic regulator called SinR. Two sinR homologs are present in C. difficile genome as an operon and henceforth labeled as sinR and sinR’. Our detailed investigation revealed that in C. difficile, the SinR and SinR’ are key master regulators needed for the regulation of several pathways including sporulation, toxin production, and motility.

International audience; Crosstalk between integrins is involved in the regulation of various cell functions including cell migration. Here we identify the interplay between the integrins alpha v beta 5/beta 6 and alpha 2 beta 1 during cell migration toward type I collagen. Human colon cancer cell lines HT29-D4 and SW480 were used as cell models. To improve our Understanding of the consequences of alpha v beta 5/beta 6 function on alpha 2 beta 1, we decreased the expression of alpha v integrins by either siRNA or lysosomal targeting strategies, or inhibited their function using, as antagonists, blocking antibodies or disintegrins. In all cases, we observed a greatly enhanced alpha 2 beta 1 integrin-dependent cell migration associated with focal adhesion rearrangements and increased outside-in signaling as demonstrated by elevated phosphorylation of focal adhesion kinase and MAPKinase (ERK1 and ERK2). The alpha v beta 5/beta 6-dependent limitation of alpha 2 beta 1 function could be overridden by TS2/16, an activating anti-beta 1 antibody. Interestingly, compared to control cells, the pharmacological inhibition of PI3Kinase or the siRNA-mediated knockdown of AKT had little effect on the high alpha 2 beta 1-mediated cell migration observed in the absence of alpha v integrins or following activation of alpha 2 beta 1 integrins by the TS2/16. These results suggest that integrins alpha v beta 5/beta 6 repress alpha 2 beta 1 possibly by interfering with their activation process and thereby modify the cell signaling regulation of alpha 2 beta 1-mediated migration. (C) 2009 Elsevier Inc. All rights reserved.

Crosstalk between integrins is involved in the regulation of various cell functions including cell migration. Here we identify the interplay between the integrins alpha v beta 5/beta 6 and alpha 2 beta 1 during cell migration toward type I collagen. Human colon cancer cell lines HT29-D4 and SW480 were used as cell models. To improve our Understanding of the consequences of alpha v beta 5/beta 6 function on alpha 2 beta 1, we decreased the expression of alpha v integrins by either siRNA or lysosomal targeting strategies, or inhibited their function using, as antagonists, blocking antibodies or disintegrins. In all cases, we observed a greatly enhanced alpha 2 beta 1 integrin-dependent cell migration associated with focal adhesion rearrangements and increased outside-in signaling as demonstrated by elevated phosphorylation of focal adhesion kinase and MAPKinase (ERK1 and ERK2). The alpha v beta 5/beta 6-dependent limitation of alpha 2 beta 1 function could be overridden by TS2/16, an activating anti-beta 1 antibody. Interestingly, compared to control cells, the pharmacological inhibition of PI3Kinase or the siRNA-mediated knockdown of AKT had little effect on the high alpha 2 beta 1-mediated cell migration observed in the absence of alpha v integrins or following activation of alpha 2 beta 1 integrins by the TS2/16. These results suggest that integrins alpha v beta 5/beta 6 repress alpha 2 beta 1 possibly by interfering with their activation process and thereby modify the cell signaling regulation of alpha 2 beta 1-mediated migration. (C) 2009 Elsevier Inc. All rights reserved.