Has the biology and treatment of pancreatic diseases evolved?

GEMMs as preclinical models for testing pancreatic cancer therapies

Pancreatic ductal adenocarcinoma is the most common form of pancreatic tumour, with a very limited survival rate and currently no available disease-modifying treatments. Despite recent advances in the production of genetically engineered mouse models (GEMMs), the development of new therapies for pancreatic cancer is still hampered by a lack of reliable and predictive preclinical animal models for this disease. Preclinical models are vitally important for assessing therapies in the first stages of the drug development pipeline, prior to their transition to the clinical arena. GEMMs carry mutations in genes that are associated with specific human diseases and they can thus accurately mimic the genetic, phenotypic and physiological aspects of human pathologies. Here, we discuss different GEMMs of human pancreatic cancer, with a focus on the Lox-Stop-Lox (LSL)-Kras(G12D); LSL-Trp53(R172H); Pdx1-cre (KPC) model, one of the most widely used preclinical models for this disease. We describe its application in preclinical research, highlighting its advantages and disadvantages, its potential for predicting clinical outcomes in humans and the factors that can affect such outcomes, and, finally, future developments that could advance the discovery of new therapies for pancreatic cancer.

Association of matrix metalloproteinase (MMP)-2 and -9 expression with extra-gastrointestinal stromal tumor metastasis

Matrix metalloproteinase (MMP)-2 and MMP-9 are important proteases involved in invasion and metastasis of various tumors. Extra-gastrointestinal stromal tumors (EGISTs) are rare neoplasms. This study was performed to assess MMP-2 and MMP-9 expression in EGIST tissue samples for association with clinicopathological data from the patients. Twenty-one surgical EGIST tissue specimens were collected for analysis of MMP-2 and MMP- 9 expression using immunohistochemistry. MMP-2 and MMP-9 proteins were expressed in all of the epithelial cell types of EGISTs, whereas they were only expressed in 75% of the spindle cell type, although there was no statistically significant difference (p>0.05). Expression of MMP-2 and MMP-9 proteins was associated with tumor size, mitotic rate, tumor necrosis, and distant metastasis (p<0.05). MMP-2 expression was linked with MMP-9 levels (p<0.05). However, there was no correlation between MMP-9 expression and age, sex, primary site, or cell morphology in any of these 21 EGIST patients (p>0.05). Moreover, expression of MMP-2 and MMP-9 proteins increased with the degree of EGIST risk. This study provided evidence of an association of MMP-2 and MMP-9 expression with advanced EGIST behavior.

Quantitative organellar proteomics analysis of rough endoplasmic reticulum from normal and acute pancreatitis rat pancreas

The rough endoplasmic reticulum (RER) is a central organelle for synthesizing and processing digestive enzymes and alteration of ER functions may participate in the pathogenesis of acute pancreatitis (AP). To comprehensively characterize the normal and diseased RER subproteome, this study quantitatively compared the protein compositions of pancreatic RER between normal and AP animals using isobaric tags (iTRAQ) and 2D LC-MALDI-MS/MS. A total of 469 unique proteins were revealed from four independent experiments using two different AP models. These proteins belong to a large number of functional categories including ribosomal proteins, translocon subunits, chaperones, secretory proteins, and glyco- and lipid-processing enzymes. A total of 37 RER proteins (25 unique in arginine-induced, 6 unique in caerulein-induced and 6 common in both models of AP) showed significant changes during AP including translational regulators and digestive enzymes, whereas only mild changes were found in some ER chaperones. The six proteins common to both AP models included a decrease in pancreatic triacylglycerol lipase precursor, Erp27, and prolyl 4-hydroxylase beta polypeptide as well as a dramatic increase in fibrinogen alpha, beta and gamma chains. These results suggest that the early stages of AP involve changes of multiple RER proteins that may affect the synthesis and processing of digestive enzymes.

Significance of expression of metastasis-related factors uPA, MMP-2, MMP-9 and TGF-β1 in gastrointestinal stromal tumors

AIM: To investigate the significance of expression of urokinase-type plasminogen activator (uPA), matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) and transforming growth factor-β1 (TGF-β1) in gastrointestinal stromal tumors (GISTs).

METHODS: The expression of uPA, MMP-2, MMP-9 and TGF-β1 mRNAs and proteins in 124 GISTs specimens was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively.

RESULTS: In gastrointestinal stromal tumors, the mRNA expression of uPA, MMP-2, MMP-9 and TGF-β1 is closely correlated with tumor stage (NIH classification), mucosal invasion and lymphatic metastasis. The mRNA expression levels of uPA, MMP-2, MMP-9 and TGF-β1 were up-regulated with increasing tumor stage, showing significant differences among low-, moderate- and high-risk GISTs. The positive rates of uPA, MMP-2, MMP-9 and TGF-β1 mRNA expression was not correlated with age, sex and histological type. Similar results were obtained for the expression of uPA, MMP-2, MMP-9 and TGF-β1 proteins in GISTs. The expression of uPA protein is positively correlated with that of TGF-β1, MMP-2 and MMP-9 (r = 0.356, 0.323 and 0.346, respectively).

CONCLUSION: The positive activation of TGF-β1 in GISTs possibly up-regulates uPA expression which in turn activates MMP-2 and MMP-9. The activation of MMP-2 and MMP-9 may lead to the degradation of extracellular matrix degradation and promote tumor invasion and metastasis.

The effect of halofuginone, a specific inhibitor of collagen type 1 synthesis, in the prevention of pancreatic fibrosis in an experimental model of severe hyperstimulation and obstruction pancreatitis

BACKGROUND

The aim of this paper is to assess the effects of halofuginone, a specific inhibitor of synthesis of collagen Type 1, on fibrogenetic process in an experimental model of early pancreatic fibrosis.

METHODS

Thirty rats were divided into three equal groups: group 1, sham laparotomy; group 2, severe hyperstimulation and obstruction pancreatitis (SHOP) with no treatment; group 3, SHOP with halofuginone treatment group. SHOP model was induced by complete pancreatic duct obstruction and daily cerulein hyperstimulation (50 microg/kg, intraperitoneally). Halofuginone was administered daily from the operative day (5 mg/kg, intraperitoneally). All of the animals were sacrificed, and blood and pancreatic tissue samples were obtained for biochemical and histopathological examination on the 5th postoperative day.

RESULTS

No mortality was observed in any group. Serum amylase, lipase, hyaluronic acid, and nitric oxide levels were significantly higher in groups 2 and 3 compared with group 1 (P < 0.05), but were significantly lower in group 3 compared with group 2 (P < 0.05). No significant differences were observed regarding serum malondialdehyde and glutathione levels between groups 1 and 3. Tissue hydroxyproline levels were found to be significantly higher in groups 2 and 3 compared with group 1 (P < 0.001), but were significantly lower in group 3 compared with group 2 (P < 0.001). Although tissue hydroxyproline levels were significantly higher in the halofuginone treatment group compared with the control group, histopathological evaluation did not reveal a significant difference between these groups regarding collagen deposition. When group 3 was compared with group 2, halofuginone significantly reduced inflammation and acinar atrophy in the pancreas as well (P < 0.05).

CONCLUSION

Halofuginone was found to be effective in reducing SHOP-related inflammation, acinar atrophy, and fibrosis in the pancreas.

Therapeutic proteasome inhibition in experimental acute pancreatitis

AIM: To establish the therapeutic potential of proteasome inhibition, we examined the therapeutic effects of MG132 (Z-Leu-Leu-Leu-aldehyde) in an experimental model of acute pancreatitis.

METHODS: Pancreatitis was induced in rats by two hourly intraperitoneal (ip) injections of cholecystokinin octapeptide (CCK; 2 × 100 μg/kg) and the proteasome inhibitor MG132 (10 mg/kg ip) was administered 30 min after the second CCK injection. Animals were sacrificed 4 h after the first injection of CCK.

RESULTS: Administering the proteasome inhibitor MG132 (at a dose of 10 mg/kg, ip) 90 min after the onset of pancreatic inflammation induced the expression of cell-protective 72 kDa heat shock protein (HSP72) and decreased DNA-binding of nuclear factor-κB (NF-κB).

Furthermore MG132 treatment resulted in milder inflammatory response and cellular damage, as revealed by improved laboratory and histological parameters of pancreatitis and associated oxidative stress.

CONCLUSION: Our findings suggest that proteasome inhibition might be beneficial not only for the prevention, but also for the therapy of acute pancreatitis.