Non-alcoholic fatty liver disease (NAFLD) is the most common chronic hepatic pathology in Western countries. It encompasses a spectrum of conditions ranging from simple steatosis to more severe and progressive non-alcoholic steatohepatitis (NASH) that can lead to hepatocellular carcinoma (HCC). Obesity and related metabolic syndrome are important risk factors for the development of NAFLD, NASH and HCC. DUSP3 is a small dual-specificity protein phosphatase with a poorly known physiological function. We investigated its role in metabolic syndrome manifestations and in HCC using a mouse knockout (KO) model. While aging, DUSP3-KO mice became obese, exhibited insulin resistance, NAFLD and associated liver damage. These phenotypes were exacerbated under high fat diet (HFD). In addition, DEN administration combined to HFD led to rapid HCC development in DUSP3-KO compared to wild type (WT) mice. DUSP3-KO mice had more serum triglycerides, cholesterol, AST and ALT compared to control WT mice under both regular chow diet (CD) and HFD. The level of fasting insulin was higher compared to WT mice, though, fasting glucose as well as glucose tolerance were normal. At the molecular level, HFD led to decreased expression of DUSP3 in WT mice. DUSP3 deletion was associated with increased and consistent phosphorylation of the insulin receptor (IR) and with higher activation of the downstream signaling pathway. In conclusion, our results support a new role for DUSP3 in obesity, insulin resistance, NAFLD and liver damage.
Abstract Dual-specificity phosphatase 3 (DUSP3) is a small phosphatase with poorly known physiological functions and for which only a few substrates are known. Using knockout mice, we recently reported that DUSP3 deficiency confers resistance to endotoxin- and polymicrobial-induced septic shock. We showed that this protection was macrophage dependent. In this study, we further investigated the role of DUSP3 in sepsis tolerance and showed that the resistance is sex dependent. Using adoptive-transfer experiments and ovariectomized mice, we highlighted the role of female sex hormones in the phenotype. Indeed, in ovariectomized females and in male mice, the dominance of M2-like macrophages observed in DUSP3−/− female mice was reduced, suggesting a role for this cell subset in sepsis tolerance. At the molecular level, DUSP3 deletion was associated with estrogen-dependent decreased phosphorylation of ERK1/2 and Akt in peritoneal macrophages stimulated ex vivo by LPS. Our results demonstrate that estrogens may modulate M2-like responses during endotoxemia in a DUSP3-dependent manner.
Abstract Genes whose expression is affected in a consistent manner by GWAS-identified risk variants and the disease process, constitute preferred drug targets. We herein combine integrated cis-eQTL analysis in 27 blood cell populations and 43 intestinal cell types of the ileum, colon and rectum, and information on gene expression in patients, to search for putative drug targets for inflammatory bowel disease (IBD). We detect >95K cis-eQTL that affect >13K e-genes and cluster in >24K regulatory modules (RM). We uncover matching RM for 140 risk loci, implicating >300 e-genes not previously connected to IBD, and find 152 IBD-matching e-genes whose expression is perturbed in the blood or gut of patients. We identify entrectinib, a small molecule inhibiting the NRLP3 inflammasome by binding NEK7, as a promising repurposing candidate for IBD.
Abstract Background & Aims The class I‐ phosphatidylinositol‐3 kinases (PI3Ks) signalling is dysregulated in almost all human cancers whereas the isoform‐specific roles remain poorly investigated. We reported that the isoform δ (PI3Kδ) regulated epithelial cell polarity and plasticity and recent developments have heightened its role in hepatocellular carcinoma (HCC) and solid tumour progression. However, its role in cholangiocarcinoma (CCA) still lacks investigation. Approach & Results Immunohistochemical analyses of CCA samples reveal a high expression of PI3Kδ in the less differentiated CCA. The RT‐qPCR and immunoblot analyses performed on CCA cells stably overexpressing PI3Kδ using lentiviral construction reveal an increase of mesenchymal and stem cell markers and the pluripotency transcription factors. CCA cells stably overexpressing PI3Kδ cultured in 3D culture display a thick layer of ECM at the basement membrane and a wide single lumen compared to control cells. Similar data are observed in vivo, in xenografted tumours established with PI3Kδ‐overexpressing CCA cells in immunodeficient mice. The expression of mesenchymal and stemness genes also increases and tumour tissue displays necrosis and fibrosis, along with a prominent angiogenesis and lymphangiogenesis, as in mice liver of AAV8‐based‐PI3Kδ overexpression. These PI3Kδ‐mediated cell morphogenesis and stroma remodelling were dependent on TGFβ/Src/Notch signalling. Whole transcriptome analysis of PI3Kδ using the cancer cell line encyclopedia allows the classification of CCA cells according to cancer progression. Conclusions Overall, our results support the critical role of PI3Kδ in the progression and aggressiveness of CCA via TGFβ/src/Notch‐dependent mechanisms and open new directions for the classification and treatment of CCA patients.
Abstract Tumour‐derived extracellular vesicles (EVs) participate in tumour progression by deregulating various physiological processes including angiogenesis and inflammation. Here we report that EVs released by endothelial cells in a mammary tumour environment participate in the recruitment of macrophages within the tumour, leading to an immunomodulatory phenotype permissive for tumour growth. Using RNA‐Seq approaches, we identified several microRNAs (miRNAs) found in endothelial EVs sharing common targets involved in the regulation of the immune system. To further study the impact of these miRNAs in a mouse tumour model, we focused on three miRNAs that are conserved between humans and mouse, that is, miR‐142‐5p, miR‐183‐5p and miR‐222‐3p. These miRNAs are released from endothelial cells in a tumour microenvironment and are transferred via EVs to macrophages. In mouse mammary tumour models, treatment with EVs enriched in these miRNAs leads to a polarization of macrophages toward an M2‐like phenotype, which in turn promotes tumour growth.
Vaccinia-H1 Related (VHR) dual-specificity phosphatase, or DUSP3, plays an important role in cell cycle regulation and its expression is altered in several human cancers. In mouse model, DUSP3 deletion prevents neo-angiogenesis and b-FGF-induced microvessel outgrowth. Considering the importance of angiogenesis in metastasis formation, our study aimed to investigate the role of DUSP3 in tumour cell dissemination. Using a Lewis Lung carcinoma (LLC) experimental metastasis model, we observed that DUSP3-/- mice developed larger lung metastases than littermate controls. DUSP3-/- bone marrow transfer to lethally irradiated DUSP3+/+ mice was sufficient to transfer the phenotype to DUSP3+/+ mice, indicating that hematopoietic cells compartment was involved in the increased tumour cell dissemination to lung tissues. Interestingly, we found a higher percentage of tumour-promoting Ly6Cint macrophages in DUSP3-/- LLC-bearing lung homogenates that was at least partially due to a better recruitment of these cells. This was confirmed by 1) the presence of higher number of the Ly6Bhi macrophages in DUSP3-/- lung homogenates and by 2) the better migration of DUSP3-/- bone marrow sorted monocytes, peritoneal macrophages and bone marrow derived macrophages (BMDMs), compared to DUSP3+/+ monocytes, macrophages and BMDMs, in response to LLC-conditioned medium. Our study demonstrates that DUSP3 phosphatase plays a key role in metastatic growth through a mechanism involving the recruitment of macrophages towards LLC-bearing lungs.
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