RESUMEN
BACKGROUND & AIMS: Mutations in the trypsinogen gene (PRSS1) cause human hereditary pancreatitis. However, it is not clear how mutant forms of PRSS1 contribute to disease development. We studied the effects of expressing mutant forms of human PRSS1 in mice. METHODS: We expressed forms of PRSS1 with and without the mutation encoding R122H (PRSS1R122H) specifically in pancreatic acinar cells under control of a full-length pancreatic elastase gene promoter. Mice that did not express these transgenes were used as controls. Mice were given injections of caerulein to induce acute pancreatitis or injections of lipopolysaccharide to induce chronic pancreatitis. Other groups of mice were fed ethanol or placed on a high-fat diet to induce pancreatitis. Pancreata were collected and analyzed by histology, immunoblots, real-time polymerase chain reaction, and immunohistochemistry. Trypsin enzymatic activity and chymotrypsin enzymatic activity were measured in pancreatic homogenates. Blood was collected and serum amylase activity was measured. RESULTS: Pancreata from mice expressing transgenes encoding PRSS1 or PRSS1R122H had focal areas of inflammation; these lesions were more prominent in mice that express PRSS1R122H. Pancreata from mice that express PRSS1 or PRSS1R122H had increased levels of heat shock protein 70 and nuclear factor (erythroid-derived 2)-like 2, and reduced levels of chymotrypsin C compared with control mice. Increased expression of PRSS1 or PRSS1R122H increased focal damage in pancreatic tissues and increased the severity of acute pancreatitis after caerulein injection. Administration of lipopolysaccharide exacerbated inflammation in mice that express PRSS1R122H compared to mice that express PRSS1 or control mice. Mice that express PRSS1R122H developed more severe pancreatitis after ethanol feeding or a high-fat diet than mice that express PRSS1 or control mice. Pancreata from mice that express PRSS1R122H had more DNA damage, apoptosis, and collagen deposition and increased trypsin activity and infiltration by inflammatory cells than mice that express PRSS1 or control mice. CONCLUSIONS: Expression of a transgene encoding PRSS1R122H in mice promoted inflammation and increased the severity of pancreatitis compared with mice that express PRSS1 or control mice. These mice might be used as a model for human hereditary pancreatitis and can be studied to determine mechanisms of induction of pancreatitis by lipopolysaccharide, ethanol, or a high-fat diet.
Asunto(s)
Inmunidad Adaptativa/genética , Expresión Génica/inmunología , Pancreatitis/genética , Transgenes/inmunología , Tripsina/inmunología , Células Acinares/inmunología , Animales , Humanos , Ratones , Ratones Transgénicos , Mutación , Páncreas/inmunología , Pancreatitis/inmunología , Tripsinógeno/inmunologíaRESUMEN
Lipocalin-2 (LCN2) promotes malignant development in many cancer types. LCN2 is upregulated in patients with pancreatic ductal adenocarcinoma (PDAC) and in obese individuals, but whether it contributes to PDAC development is unclear. In this study, we investigated the effects of Lcn2 depletion on diet-induced obesity, inflammation, and PDAC development. Mice with acinar cell-specific expression of KrasG12D were crossed with Lcn2-depleted animals and fed isocaloric diets with varying amounts of fat content. Pancreas were collected and analyzed for inflammation, pancreatic intraepithelial neoplasia (PanIN), and PDAC. We also used a syngeneic orthotopic PDAC mouse model to study tumor growth in the presence or absence of Lcn2 expression. In addition, to understand the mechanistic role of how LCN2 could be mediating PDAC, we studied LCN2 and its specific receptor solute carrier family 22 member 17 (SLC22A17) in human pancreatic cancer stellate cells (PSC), key mediators of the PDAC stroma. Depletion of Lcn2 diminished extracellular matrix deposition, immune cell infiltration, PanIN formation, and tumor growth. Notably, it also increased survival in both obesity-driven and syngeneic orthotopic PDAC mouse models. LCN2 modulated the secretion of proinflammatory cytokines in PSC of the PDAC tumor microenvironment, whereas downregulation of LCN2-specific receptor SLC22A17 blocked these effects. Our results reveal how LCN2 acts in the tumor microenvironment links obesity, inflammation, and PDAC development. Cancer Res; 77(10); 2647-60. ©2017 AACR.