Background & Aims Differentiated pancreatic acinar cells expressing endogenous levels of mutant K-Ras do not spontaneously develop pancreatic ductal adenocarcinoma (PDAC). However, we hypothesized that acinar cells would develop PDAC in the presence of Ras activity levels mimicking those of human tumor cells. Methods We measured Ras activity in PDAC cells from mice and humans using a Raf pull-down assay. We compared the effects of acinar cell expression of mutant K-Ras at endogenous and elevated levels on Ras activity and on the development of PDAC. Results Ras activity was greatly elevated in PDAC cells compared with nontransformed cells expressing endogenous levels of mutant K-Ras. Expression of endogenous levels of mutant K-Ras in differentiated acinar cells resulted in moderately elevated Ras activity and in sparse murine pancreatic intraepithelial neoplasias (mPanINs) that did not spontaneously advance to PDAC unless the tumor suppressor p53 was simultaneously deleted. In contrast, expression of mutant K-Ras at higher levels generated Ras activity equal to that in PDAC. High Ras activity mimicking levels in PDAC led to acinar cell senescence and generated inflammation and fibrosis resembling the histologic features of chronic pancreatitis. With higher Ras activity in acinar cells, abundant mPanINs formed and spontaneously progressed to both cystic papillary carcinoma and metastatic PDAC. Conclusions There is an important relationship between Ras activity levels and the progression of PDAC. Sufficient Ras activity in pancreatic acinar induces several important pancreatic disease manifestations not previously reported and supports a potential direct linkage between chronic pancreatitis, cystic papillary carcinoma, and PDAC.

Currently, an effective targeted therapy for pancreatitis is lacking. Hereditary pancreatitis (HP) is a heritable, autosomal-dominant disorder with recurrent acute pancreatitis (AP) progressing to chronic pancreatitis (CP) and a markedly increased risk of pancreatic cancer. In 1996, mutations in PRSS1 were linked to the development of HP. Here, we developed a mouse model by inserting a full-length human PRSS1^R122H gene, the most commonly mutated gene in human HP, into mice. Expression of PRSS1^R122H protein in the pancreas markedly increased stress signaling pathways and exacerbated AP. After the attack of AP, all PRSS1^R122H mice had disease progression to CP, with similar histologic features as those observed in human HP. By comparing PRSS1^R122H mice with PRSS1^WT mice, as well as enzymatically inactivated Dead-PRSS1^R122H mice, we unraveled that increased trypsin activity is the mechanism for R122H mutation to sensitize mice to the development of pancreatitis. We further discovered that trypsin inhibition, in combination with anticoagulation therapy, synergistically prevented progression to CP in PRSS1^R122H mice. These animal models help us better understand the complex nature of this disease and provide powerful tools for developing and testing novel therapeutics for human pancreatitis.

Although abdominal pain is one of the major criteria to diagnose acute pancreatitis (AP), there are no standardized guidelines to treat this troublesome symptom in the hospital setting. The aims of the study are to conduct a meta-analysis and to assess the efficacy of nonopioids vs opioids for pain management in AP. We searched the medical literature through May 2021 to identify randomized controlled trials that examined the efficacy of opioids with nonopioids in AP pain management. Efficacy was reported as odds ratio (OR) with 95% confidence intervals (CIs) of each comparison tested. We identified 7 eligible randomized controlled trials, containing 389 patients. No significant difference in terms of pain intensity at day 1 (OR 0.82, 95% CI −2.55 to 4.19) was found between opioids and nonopioids. Nonopioids have a significantly high risk of supplementary analgesic use compared with opioids (OR 3.87, 95% CI 1.25–12.04). However, this significance is not seen when comparing nonsteroidal anti-inflammatory drugs and paracetamol with opioids (OR 1.67, 95% CI 0.73–3.82) after excluding trials with procaine. Opioids did not show a significant increase in the complications of pancreatitis, nausea and vomiting, sedation, and deaths when compared with nonopioids. We found nonopioids, especially nonsteroidal anti-inflammatory drugs and paracetamol, can provide adequate pain relief in patients with AP with no change in supplementary analgesic use and adverse events when compared with opioids. Further research is needed to optimize the use of nonopioids along or in combination with opioids for better pain control in patients with AP.