Pancreatic ductal adenocarcinoma is an aggressive cancer that interacts with stromal cells to produce a highly inflammatory tumor microenvironment that promotes tumor growth and invasiveness. The precise interplay between tumor and stroma remains poorly understood. TLRs mediate interactions between environmental stimuli and innate immunity and trigger proinflammatory signaling cascades. Our finding that TLR7 expression is upregulated in both epithelial and stromal compartments in human and murine pancreatic cancer led us to postulate that carcinogenesis is dependent on TLR7 signaling. In a mouse model of pancreatic cancer, TLR7 ligation vigorously accelerated tumor progression and induced loss of expression of PTEN, p16, and cyclin D1 and upregulation of p21, p27, p53, c-Myc, SHPTP1, TGF-β, PPARγ, and cyclin B1. Furthermore, TLR7 ligation induced STAT3 activation and interfaced with Notch as well as canonical NF-κB and MAP kinase pathways, but downregulated expression of Notch target genes. Moreover, blockade of TLR7 protected against carcinogenesis. Since pancreatic tumorigenesis requires stromal expansion, we proposed that TLR7 ligation modulates pancreatic cancer by driving stromal inflammation. Accordingly, we found that mice lacking TLR7 exclusively within their inflammatory cells were protected from neoplasia. These data suggest that targeting TLR7 holds promise for treatment of human pancreatic cancer.

Acetaminophen (APAP) overdose is one of the most frequent causes of acute liver failure in the United States and is primarily mediated by toxic metabolites which accumulate in the liver upon depletion of glutathione stores. However, cells of the innate immune system, including NK cells, neutrophils, and Kupffer cells, have also been implicated in the centrilobular liver necrosis associated with APAP. We have recently shown that dendritic cells (DC) regulate intra-hepatic inflammation in chronic liver disease and, therefore, postulated that DC may also modulate the hepatotoxic effects of APAP. We found that DC immune-phenotype was markedly altered after APAP challenge. In particular, liver DC expressed higher MHC II, co-stimulatory molecules, and Toll-like Receptors, and produced higher IL-6, MCP-1, and TNF-α. Conversely, spleen DC were unaltered. However, APAP-induced centrilobular necrosis, and its associated mortality, was markedly exacerbated upon DC depletion. Conversely, endogenous DC expansion using FMS-like tyrosine kinase 3 ligand (Flt3L) protected mice from APAP injury. Our mechanistic studies showed that APAP liver DC had the particular capacity to prevent NK cell activation and induced neutrophil apoptosis. Nevertheless, the exacerbated hepatic injury in DC depleted mice challenged with APAP was independent of NK cells and neutrophils or numerous immune modulatory cytokines and chemokines. Conclusions Taken together, these data indicate that liver DC protect against APAP toxicity while their depletion is associated with exacerbated hepatotoxicity.

Background & Aims Acute pancreatitis increases morbidity and mortality from organ necrosis by mechanisms that are incompletely understood. Dendritic cells (DCs) can promote or suppress inflammation, depending on their subtype and context. We investigated the roles of DC in development of acute pancreatitis. Methods Acute pancreatitis was induced in CD11c.DTR mice using caerulein or L-arginine; DCs were depleted by administration of diphtheria toxin. Survival was analyzed using Kaplan-Meier analysis. Results Numbers of MHC II+CD11c+DC increased 100-fold in pancreas of mice with acute pancreatitis, to account for nearly 15% of intra-pancreatic leukocytes. Intra-pancreatic DC acquired an immune phenotype in mice with acute pancreatitis; they expressed higher levels of MHC II and CD86 and increased production of interleukin-6, membrane cofactor protein (MCP)-1, and tumor necrosis factor (TNF)-α. However, rather than inducing an organ-destructive inflammatory process, DC were required for pancreatic viability; the exocrine pancreas died in mice that were depleted of DC and challenged with caerulein or L-arginine. All mice with pancreatitis that were depleted of DC died from acinar cell death within 4 days. Depletion of DC from mice with pancreatitis resulted in neutrophil infiltration and increased levels of systemic markers of inflammation. However, the organ necrosis associated with depletion of DC did not require infiltrating neutrophils, activation of NF-κB, or signaling by mitogen-activated protein kinase or TNF-α. Conclusions DC are required for pancreatic viability in mice with acute pancreatitis and might protect organs against cell stress.

RAS is the most frequently mutated oncogene in human cancers. Despite decades of effort, anti-RAS therapies have remained elusive. Isoprenylcysteine carboxylmethyltransferase (ICMT) methylates RAS and other CaaX-containing proteins, but its potential as a target for cancer therapy has not been fully evaluated. We crossed a Pdx1-Cre;LSL-Kras G12D mouse, which is a model of pancreatic ductal adenocarcinoma (PDA), with a mouse harboring a floxed allele of Icmt. Surprisingly, we found that ICMT deficiency dramatically accelerated the development and progression of neoplasia. ICMT-deficient pancreatic ductal epithelial cells had a slight growth advantage and were resistant to premature senescence by a mechanism that involved suppression of cyclin-dependent kinase inhibitor 2A (p16 INK4A ) expression. ICMT deficiency precisely phenocopied Notch1 deficiency in the Pdx1-Cre;LSL-Kras G12D model by exacerbating pancreatic intraepithelial neoplasias, promoting facial papillomas, and derepressing Wnt signaling. Silencing ICMT in human osteosarcoma cells decreased Notch1 signaling in response to stimulation with cell-surface ligands. Additionally, targeted silencing of Ste14, the Drosophila homolog of Icmt, resulted in defects in wing development, consistent with Notch loss of function. Our data suggest that ICMT behaves like a tumor suppressor in PDA because it is required for Notch1 signaling.Introduction RAS is the most frequently mutated oncogene in human cancer (1). This has made RAS the target of drug discovery efforts for more than three decades, but effective anti-RAS therapies have remained elusive (2). RAS is a prototypical small GTPase that functions as a binary molecular switch to regulate a number of signaling pathways including those that control growth and differentiation. RAS is inactive when GDP bound and is active when it binds GTP. The GDP/GTP cycle is controlled by guanine nucleotide exchange factors (GEFs) that activate RAS and by GTPase-activating proteins (GAPs) that dramatically accelerate the rate of GTP hydrolysis catalyzed by RAS, thereby limiting RAS activity (3). The oncogenic mutations found in human cancer are one of several single nucleotide changes in codons 12, 13, or 61 that render RAS insensitive to GAPs and reduce the intrinsic rate of GTP hydrolysis, thus allowing the accumulation of GTP-bound, activated RAS (1, 4). Attempts to devise therapeutic agents that reverse the accumulation of GTP-bound RAS have failed. Accordingly, investigators have taken an alternate approach driven by another hallmark of RAS biology: its regulation of signaling pathways only when associated with cellular membranes (5).RAS is a peripheral membrane protein that gains affinity for membranes as a consequence of a series of posttranslational modifications of a C-terminal CaaX motif (6). The CaaX sequence is first modified by farnesyltransferase (FTase), which adds a farnesyl lipid to the cysteine. Next, RAS-converting enzyme 1 (RCE1) removes the aaX amino acids. Finally, isoprenylcysteine carboxylmethyltransferas...

Risk of type 1 diabetes at 3 years is high for initially multiple and single Ab+ IT and multiple Ab+ NT. Genetic predisposition, age, and male sex are significant risk factors for development of Ab+ in twins.