Pancreatitis accounts for significant morbidity and mortality in the USA. Currently there are no specific treatments for pancreatitis, primarily due to are lack of mechanistic understanding. We have recently observed that high levels of Ras activity generated by over-expression of mutant K-Ras cause pancreatitis. This indicates that the signaling pathways activated by Ras are sufficient to initiate pathological responses in acinar cells. However, it is unclear that high levels of mutant Ras expression represent a physiologic model. Therefore, we investigated the influence of acinar cell expression of mutant K-Ras at an endogenous level. We found that endogenous levels of mutant K-Ras cause no obvious changes in the pancreas. However, in mice with low mutant K-Ras expression in acinar cells, physiologic stimuli such as trypsin inhibitor feeding induced chronic pancreatitis. Therefore, we have formulated a working hypothesis that the Ras signaling pathway integrates both physiologic and pathologic stimuli and when activity levels exceed a threshold pathological responses are initiated. We will identify the important mechanisms involved in these responses by pursuing the following specific aims: 1) Identify physiologic stimuli that generate pathological responses in the presence of endogenous levels of mutant K-Ras. In this aim, we will determine whether diets high in fat or protein can induce pancreatitis in a background of low mutant Ras and whether this effect is mediated by CCK. We will also investigate the effects of the secretagogues neuromedin b and secretin, which do not induce pancreatitis in control animals, to determine whether their signaling mechanisms will integrate with Ras in animals bearing mutant K-Ras in acinar cells. 2) Identify mechanisms down-stream of Ras which are necessary and/or sufficient to initiate pancreatic inflammation and fibrosis. Ras interacts directly with many signaling molecules. However, we will focus on three for which there is already evidence that they may be involved in pancreatitis, Erks, PI3K and Src. We will utilize a combination of genetic and pharmacological approaches to determine whether these signaling pathways are necessary or sufficient for the observed pathological effects. 3) Determine the role of p53 in the inflammation and fibrosis associated with Ras activity induced pancreatitis. Elevated levels of Ras activity lead to p53 activation. We hypothesize that this is the threshold at which Ras activity becomes pathological. We further suggest that p53 mediates inflammatory effects by inducing the activation of caspase 1. We will test these hypotheses using a combination of genetic and pharmacological approaches. Together these studies using novel models will provide important new insights into the mechanisms involved in acute and chronic pancreatitis and some observations may be directly relevant to a segment of the population which carries silent Ras mutations.
The development of new treatments for pancreatitis had been hindered by the lack of physiologically relevant animal models. We have developed for the first time an animal model with a modified genetic background that develops chronic pancreatitis after manipulations that are physiologically relevant and which are not directly injurious. This new model will provide an opportunity to discover important new details about the mechanisms which initiate pancreatic disease.
|Gomez-Chou, Sobeyda B; Swidnicka-Siergiejko, Agnieszka Katarzyna; Badi, Niharika et al. (2017) Lipocalin-2 Promotes Pancreatic Ductal Adenocarcinoma by Regulating Inflammation in the Tumor Microenvironment. Cancer Res 77:2647-2660|
|Swidnicka-Siergiejko, A K; Gomez-Chou, S B; Cruz-Monserrate, Z et al. (2017) Chronic inflammation initiates multiple forms of K-Ras-independent mouse pancreatic cancer in the absence of TP53. Oncogene 36:3149-3158|
|Gaziova, Ivana; Jackson, Daniel; Boor, Paul J et al. (2016) The MET Receptor Tyrosine Kinase Confers Repair of Murine Pancreatic Acinar Cells following Acute and Chronic Injury. PLoS One 11:e0165485|
|Logsdon, Craig D; Lu, Weiqin (2016) The Significance of Ras Activity in Pancreatic Cancer Initiation. Int J Biol Sci 12:338-46|
|Logsdon, Craig D; Arumugam, Thiruvengadam; Ramachandran, Vijaya (2015) Animal Models of Gastrointestinal and Liver Diseases. The difficulty of animal modeling of pancreatic cancer for preclinical evaluation of therapeutics. Am J Physiol Gastrointest Liver Physiol 309:G283-91|
|Fu, Yong; Cruz-Monserrate, Zobeida; Helen Lin, H et al. (2015) Ductal activation of oncogenic KRAS alone induces sarcomatoid phenotype. Sci Rep 5:13347|
|Cruz-Monserrate, Zobeida; Roland, Christina L; Deng, Defeng et al. (2014) Targeting pancreatic ductal adenocarcinoma acidic microenvironment. Sci Rep 4:4410|
|Huang, H; Daniluk, J; Liu, Y et al. (2014) Oncogenic K-Ras requires activation for enhanced activity. Oncogene 33:532-5|
|Roland, Christina L; Arumugam, Thiruvengadam; Deng, Defeng et al. (2014) Cell surface lactate receptor GPR81 is crucial for cancer cell survival. Cancer Res 74:5301-10|
|Charo, Chantale; Holla, Vijaykumar; Arumugam, Thiruvengadam et al. (2013) Prostaglandin E2 regulates pancreatic stellate cell activity via the EP4 receptor. Pancreas 42:467-74|
Showing the most recent 10 out of 40 publications