Induction of pancreatitis in mice with susceptibility to pancreatic cancer

Overexpression of Tn antigen induces chronic pancreatitis in mice

Altered O-glycosylation is a key contributor to various pathophysiological processes. Notably, the expression of the Tn antigen is primarily attributed to dysfunction of the chaperone Cosmc, while the overexpression of polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) has also been implicated in numerous diseases. We generated a transgenic mouse model with conditional Cosmc-knockout and simultaneous overexpression of polypeptide N-acetylgalactosaminyltransferase 2 (GalNT2) mediated by the pancreas-specific transcription factor 1a (Ptf1a)-Cre mouse strain to investigate the effect of Tn antigen overexpression on the pancreas in vivo. Histopathological examination of the transgenic pancreas revealed a chronic pancreatitis phenotype with interlobular fibrosis and focal necrosis after only a few weeks as a result of Tn antigen overexpression. In the later stages, there was a progressive loss of pancreatic parenchyma with consecutive exocrine pancreatic insufficiency and malnutrition in the transgenic mice. Flow cytometric analyses have also confirmed that significant infiltration of immune cells occurs in the course of pancreatitis. In the transgenic mouse model presented here, we demonstrated that overexpression of the Tn antigen in the pancreas results in chronic pancreatitis, highlighting the pathophysiological importance of truncated O-glycosylation.

Sex-dependent modulation of caerulein-induced acute pancreatitis in C57BL/6J mice

Acute pancreatitis (AP) is a life-threatening condition, with a higher mortality rate in men than women and in which estrogens might play a protective role. This study aimed to investigate sex-dependent differences in a mouse model of caerulein-induced AP. Thirty-six C57BL/6J mice (19 females and 17 males) were treated intraperitoneally with phosphate-buffered saline or caerulein, and sacrificed 12 hours, 2 days, or 7 days after the last injection. Blood was collected for amylase, lipase, and glucose determination. Severity and extent of inflammation, apoptosis, and acinar to ductal metaplasia (ADM) in pancreatic tissue were scored histologically and total macrophages, major histocompatibility complex (MHC)-II+ cells, M2 macrophages, T and B cells, neutrophils, apoptosis, and ADM were marked immunohistochemically and quantified by digital image analysis. Serum amylase had a peak at 12 hours, without differences between the sexes. In females, pancreatitis reached a peak at 12 hours with a fast recovery while, in males, the peak was delayed to day 2 with residual apoptosis still present. Macrophages were the main inflammatory cell population, followed by T cells, B cells and neutrophils, without differences between sexes. In males, CD206+ cells and apoptosis were higher at both days 2 and 7, and cytokeratin-19+ (CK19+) ADM was higher at day 7 compared with females. The results of this study revealed a faster onset and resolution of caerulein-induced AP in female mice compared with male mice, supporting a sex-dependent modulation of acute pancreatitis.

Relevance of Carcinogen-Induced Preclinical Cancer Models

Chemical agents can cause cancer in animals by damaging their DNA, mutating their genes, and modifying their epigenetic signatures. Carcinogen-induced preclinical cancer models are useful for understanding carcinogen-induced human cancers, as they can reproduce the diversity and complexity of tumor types, as well as the interactions with the host environment. However, these models also have some drawbacks that limit their applicability and validity. For instance, some chemicals may be more effective or toxic in animals than in humans, and the tumors may differ in their genetics and phenotypes. Some chemicals may also affect normal cells and tissues, such as by causing oxidative stress, inflammation, and cell death, which may alter the tumor behavior and response to therapy. Furthermore, some chemicals may have variable effects depending on the exposure conditions, such as dose, route, and duration, as well as the animal characteristics, such as genetics and hormones. Therefore, these models should be carefully chosen, validated, and standardized, and the results should be cautiously interpreted and compared with other models. This review covers the main features of chemically induced cancer models, such as genetic and epigenetic changes, tumor environment, angiogenesis, invasion and metastasis, and immune response. We also address the pros and cons of these models and the current and future challenges for their improvement. This review offers a comprehensive overview of the state of the art of carcinogen-induced cancer models and provides new perspectives for cancer research.

Membrane Lipid Derivatives: Roles of Arachidonic Acid and Its Metabolites in Pancreatic Physiology and Pathophysiology

One of the most important constituents of the cell membrane is arachidonic acid. Lipids forming part of the cellular membrane can be metabolized in a variety of cellular types of the body by a family of enzymes termed phospholipases: phospholipase A2, phospholipase C and phospholipase D. Phospholipase A2 is considered the most important enzyme type for the release of arachidonic acid. The latter is subsequently subjected to metabolization via different enzymes. Three enzymatic pathways, involving the enzymes cyclooxygenase, lipoxygenase and cytochrome P450, transform the lipid derivative into several bioactive compounds. Arachidonic acid itself plays a role as an intracellular signaling molecule. Additionally, its derivatives play critical roles in cell physiology and, moreover, are involved in the development of disease. Its metabolites comprise, predominantly, prostaglandins, thromboxanes, leukotrienes and hydroxyeicosatetraenoic acids. Their involvement in cellular responses leading to inflammation and/or cancer development is subject to intense study. This manuscript reviews the findings on the involvement of the membrane lipid derivative arachidonic acid and its metabolites in the development of pancreatitis, diabetes and/or pancreatic cancer.

Mechanism of Action and Structure-Activity Relationships of Tetracyclic Small Molecules Acting as Universal Positive Allosteric Modulators of the Cholecystokinin Receptor

As part of an ongoing effort to develop a drug targeting the type 1 cholecystokinin receptor (CCK1R) to help prevent and/or treat obesity, we recently performed a high throughput screening effort of small molecules seeking candidates that enhanced the action of the natural agonist, CCK, thus acting as positive allosteric modulators without exhibiting intrinsic agonist action. Such probes would be expected to act in a temporally finite way to enhance CCK action to induce satiety during and after a meal and potentially even modulate activity at the CCK1R in a high cholesterol environment present in some obese patients. The current work focuses on the best scaffold, representing tetracyclic molecules identified through high throughput screening we previously reported. Extensive characterization of the two top "hits" from the previous effort demonstrated them to fulfill the desired pharmacologic profile. We undertook analog-by-catalog expansion of this scaffold using 65 commercially available analogs. In this effort, we were able to eliminate an off-target effect observed for this scaffold while retaining its activity as a positive allosteric modulator of CCK1R in both normal and high cholesterol membrane environments. These insights should be useful in the rational medicinal chemical enhancement of this scaffold and in the future development of candidates to advance to pre-clinical proof-of-concept and to clinical trials.

Methods of a New Chronic Pancreatitis and Spontaneous Pancreatic Cancer Mouse Model Using Retrograde Pancreatic Duct Injection of Dibutyltin Dichloride

The current study aimed to develop a new chronic pancreatitis and spontaneous pancreatic cancer model on C57/BL6 mouse through retrograde pancreatic duct injection of dibutyltin dichloride (DBTC) and explore its basic pathological changes as compared to the previous published chronic pancreatitis model through tail vein injection of DBTC with alcohol drinking. C57/BL6 mice were randomly divided into 3 groups: CG (control group; n = 15), VG (tail vein injection of DBTC (8 mg/kg) with 10% alcohol drinking group; n = 20), and PG (retrograde pancreatic duct injection of DBTC group (1 mg/kg); n = 30). Five mice in each group were sacrificed at a specific time point after the first treatment. The pathological section was observed. The activities of amylase, bilirubin, and hyaluronic acid in serum were determined. The expression of fibronectin, COL1A1, α-SMA, MMP-1, and TIMP-1 in the pancreas was assayed. Severe fibrosis of the pancreas with inflammatory cell infiltration could be observed on day 21 in the PG. In the VG, slight fibrosis of the pancreas with inflammatory cell infiltration was observed on day 28. There were significant differences in serum amylase, bilirubin, and hyaluronic acid levels between the PG and VG. The protein level of COL1A1 and α-SMA significantly increased in the PG. The mRNA expression of TIMP-1 is upregulated and the MMP-1 mRNA level is downregulated in the PG. Finally, typical neoplastic pathological change is significantly obvious in the PG. In conclusion, we established and validated a new chronic pancreatitis (CP) and spontaneous pancreatic cancer mouse model through retrograde injection of DBTC into the pancreatic duct. Previously reported mouse model through tail vein injection of DBTC with alcohol drinking could not cause obvious CP and neoplastic pathological change in mice.