Heavy metals in cigarette smoke strongly inhibit pancreatic ductal function and promote development of chronic pancreatitis.

BACKGROUND AND AIMS: Smoking is recognised as an independent risk factor in the development of chronic pancreatitis (CP). Cystic fibrosis transmembrane conductance regulator (CFTR) function and ductal fluid and bicarbonate secretion are also known to be impaired in CP, so it is crucial to understand the relationships between smoking, pancreatic ductal function and the development of CP. METHODS: We measured sweat chloride (Cl-) concentrations in patients with and without CP, both smokers and non-smokers, to assess CFTR activity. Serum heavy metal levels and tissue cadmium concentrations were determined by mass spectrometry in smoking and non-smoking patients. Guinea pigs were exposed to cigarette smoke, and cigarette smoke extract (CSE) was prepared to characterise its effects on pancreatic HCO3 - and fluid secretion and CFTR function. We administered cerulein to both the smoking and non-smoking groups of mice to induce pancreatitis. RESULTS: Sweat samples from smokers, both with and without CP, exhibited elevated Cl- concentrations compared to those from non-smokers, indicating a decrease in CFTR activity due to smoking. Pancreatic tissues from smokers, regardless of CP status, displayed lower CFTR expression than those from non-smokers. Serum levels of cadmium and mercury, as well as pancreatic tissue cadmium, were increased in smokers. Smoking, CSE, cadmium, mercury and nicotine all hindered fluid and HCO3 - secretion and CFTR activity in pancreatic ductal cells. These effects were mediated by sustained increases in intracellular calcium ([Ca2+]i), depletion of intracellular ATP (ATPi) and mitochondrial membrane depolarisation. CONCLUSION: Smoking impairs pancreatic ductal function and contributes to the development of CP. Heavy metals, notably cadmium, play a significant role in the harmful effects of smoking. KEY POINTS: Smoking and cigarette smoke extract diminish pancreatic ductal fluid and HCO3 - secretion as well as the expression and function of CFTR Cd and Hg concentrations are significantly higher in the serum samples of smokers Cd accumulates in the pancreatic tissue of smokers.

Intraductal papillary mucinous neoplasm of the pancreas: Cytomorphology, imaging, molecular profile, and prognosis.

BACKGROUND: Intraductal papillary mucinous neoplasm (IPMN) constitutes up to 20% of all pancreatic resections, and has been increasing in recent years. Histomorphological findings of IPMN are well established; however, there are not many published papers regarding the cytological findings of IPMN on fine needle aspiration (FNA) specimens. We review the cytomorphological features, molecular profile, imaging findings, and prognosis of IPMN. METHODS: The English literature was thoroughly searched with key phrases containing IPMN. OBSERVATIONS: IPMN is a rare entity, affecting men and women equally and is usually diagnosed at the age of 60-70 years. The characteristic imaging features include a cystic lesion with associated dilatation of the main or branch pancreatic duct, and atrophy of surrounding pancreatic parenchyma. Cytomorphological features of IPMN include papillary fragments of mucinous epithelium in a background of abundant thick extracellular mucin, a hallmark feature. IPMNs should be evaluated for high-grade dysplasia, which manifests with nuclear atypia, nuclear moulding, prominent nucleoli, nuclear irregularity, and cellular crowding. Molecular profiling of IPMN along with carcinoembryonic antigen and amylase levels is useful in predicting malignancy or high-grade dysplasia arising in IPMN. Overall, the prognosis of IPMN is excellent except in those cases with high-grade dysplasia and malignant transformation. Postoperative surveillance is required for resected IPMNs. CONCLUSION: IPMN requires a multidisciplinary approach for management. Cytomorphological findings of IPMN on FNA, in conjunction with tumour markers in pancreatic fluid cytology and imaging findings, are of paramount importance in clinical decision-making for IPMN.

Pancreatic ductal deletion of S100A9 alleviates acute pancreatitis by targeting VNN1-mediated ROS release to inhibit NLRP3 activation.

Recent studies have proven that the overall pathophysiology of pancreatitis involves not only the pancreatic acinar cells but also duct cells, however, pancreatic duct contribution in acinar cells homeostasis is poorly known and the molecular mechanisms leading to acinar insult and acute pancreatitis (AP) are unclear. Our previous work also showed that S100A9 protein level was notably increased in AP rat pancreas through iTRAQ-based quantitative proteomic analysis. Therefore, we investigated the actions of injured duct cells on acinar cells and the S100A9-related effects and mechanisms underlying AP pathology in the present paper. Methods: In this study, we constructed S100A9 knockout (s100a9-/-) mice and an in vitro coculture system for pancreatic duct cells and acinar cells. Moreover, a variety of small molecular inhibitors of S100A9 were screened from ChemDiv through molecular docking and virtual screening methods. Results: We found that the upregulation of S100A9 induces cell injury and inflammatory response via NLRP3 activation by targeting VNN1-mediated ROS release; and loss of S100A9 decreases AP injury in vitro and in vivo. Moreover, molecular docking and mutant plasmid experiments proved that S100A9 has a direct interaction with VNN1 through the salt bridges formation of Lys57 and Glu92 residues in S100A9 protein. We further found that compounds C42H60N4O6 and C28H29F3N4O5S can significantly improve AP injury in vitro and in vivo through inhibiting S100A9-VNN1 interaction. Conclusions: Our study showed the important regulatory effect of S100A9 on pancreatic duct injury during AP and revealed that inhibition of the S100A9-VNN1 interaction may be a key therapeutic target for this disease.

Overcoming Adaptive Resistance to KRAS and MEK Inhibitors by Co-targeting mTORC1/2 Complexes in Pancreatic Cancer.

Activating KRAS mutations are found in over 90% of pancreatic ductal adenocarcinomas (PDACs), yet KRAS has remained a difficult target to inhibit pharmacologically. Here, we demonstrate, using several human and mouse models of PDACs, rapid acquisition of tumor resistance in response to targeting KRAS or MEK, associated with integrin-linked kinase (ILK)-mediated increased phosphorylation of the mTORC2 component Rictor, and AKT. Although inhibition of mTORC1/2 results in a compensatory increase in ERK phosphorylation, combinatorial treatment of PDAC cells with either KRAS (G12C) or MEK inhibitors, together with mTORC1/2 inhibitors, results in synergistic cytotoxicity and cell death reflected by inhibition of pERK and pRictor/pAKT and of downstream regulators of protein synthesis and cell survival. Relative to single agents alone, this combination leads to durable inhibition of tumor growth and metastatic progression in vivo and increased survival. We have identified an effective combinatorial treatment strategy using clinically viable inhibitors, which can be applied to PDAC tumors with different KRAS mutations.

Concerted cell and in vivo screen for pancreatic ductal adenocarcinoma (PDA) chemotherapeutics.

PDA is a major cause of US cancer-related deaths. Oncogenic Kras presents in 90% of human PDAs. Kras mutations occur early in pre-neoplastic lesions but are insufficient to cause PDA. Other contributing factors early in disease progression include chronic pancreatitis, alterations in epigenetic regulators, and tumor suppressor gene mutation. GPCRs activate heterotrimeric G-proteins that stimulate intracellular calcium and oncogenic Kras signaling, thereby promoting pancreatitis and progression to PDA. By contrast, Rgs proteins inhibit Gi/q-coupled GPCRs to negatively regulate PDA progression. Rgs16::GFP is expressed in response to caerulein-induced acinar cell dedifferentiation, early neoplasia, and throughout PDA progression. In genetically engineered mouse models of PDA, Rgs16::GFP is useful for pre-clinical rapid in vivo validation of novel chemotherapeutics targeting early lesions in patients following successful resection or at high risk for progressing to PDA. Cultured primary PDA cells express Rgs16::GFP in response to cytotoxic drugs. A histone deacetylase inhibitor, TSA, stimulated Rgs16::GFP expression in PDA primary cells, potentiated gemcitabine and JQ1 cytotoxicity in cell culture, and Gem + TSA + JQ1 inhibited tumor initiation and progression in vivo. Here we establish the use of Rgs16::GFP expression for testing drug combinations in cell culture and validation of best candidates in our rapid in vivo screen.

Immunotherapeutic strategies in pancreatic ductal adenocarcinoma (PDAC): current perspectives and future prospects.

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest human malignancies with a dismal prognosis. During PDAC progression, the immune response is affected as cancer cells evade detection and elimination. Recently, there have been advances in the treatment of PDAC using immunotherapy, although a lot more work is yet to be done. In this review, we discuss these advances, challenges and potentials. We focus on existing and potential immune targets for PDAC, drugs used to target them, and some clinical trials conducted so far with them. Finally, novel targets in the tumour microenvironment such as stromal cells and other potential future areas to explore including bacterial therapy and the use of neoantigens in immunotherapy are highlighted.

Copper promotes sheep pancreatic duct organoid growth by activation of an antioxidant protein 1-dependent MEK-ERK pathway.

Proper amounts of copper supplemented in livestock feed improve the physical growth and traits of farm animals. The pancreas is an important organ with both exocrine and endocrine portions. To investigate the role and mechanism of copper in the sheep pancreas, we first established sheep pancreatic duct organoids (sPDOs). We found that an appropriate amount of copper benefited the formation and growth of sPDOs, whereas excess or deficient copper damaged sPDOs. We found that the proliferation-stimulating effect of copper was related to the copper chaperone antioxidant protein 1 (ATOX1)-dependent activation of MEK-ERK1/2 signaling. Atox1 knockdown suppressed the cell proliferation of sPDOs, even in the presence of the MEK activator. These results indicate that moderate concentrations of copper promote sPDO growth through ATOX1-regulated cell proliferation by activation of MEK-ERK. Moreover, our study indicates that organoids may be a useful model to study organ growth mechanisms in livestock.

BCAT2-mediated BCAA catabolism is critical for development of pancreatic ductal adenocarcinoma.

Branched-chain amino acid (BCAA) metabolism is potentially linked with development of pancreatic ductal adenocarcinoma (PDAC)1-4. BCAA transaminase 2 (BCAT2) was essential for the collateral lethality conferred by deletion of malic enzymes in PDAC and the BCAA-BCAT metabolic pathway contributed to non-small-cell lung carcinomas (NSCLCs) other than PDAC3,4. However, the underlying mechanism remains undefined. Here we reveal that BCAT2 is elevated in mouse models and in human PDAC. Furthermore, pancreatic tissue-specific knockout of Bcat2 impedes progression of pancreatic intraepithelial neoplasia (PanIN) in LSL-KrasG12D/+; Pdx1-Cre (KC) mice. Functionally, BCAT2 enhances BCAA uptake to sustain BCAA catabolism and mitochondrial respiration. Notably, BCAA enhances growth of pancreatic ductal organoids from KC mice in a dose-dependent manner, whereas addition of branched-chain α-keto acid (BCKA) and nucleobases rescues growth of KC organoids that is suppressed by BCAT2 inhibitor. Moreover, KRAS stabilizes BCAT2, which is mediated by spleen tyrosine kinase (SYK) and E3 ligase tripartite-motif-containing protein 21 (TRIM21). In addition, BCAT2 inhibitor ameliorates PanIN formation in KC mice. Of note, a lower-BCAA diet also impedes PDAC development in mouse models of PDAC. Thus, BCAT2-mediated BCAA catabolism is critical for development of PDAC harbouring KRAS mutations. Targeting BCAT2 or lowering dietary BCAA may have translational significance.

Glucose-Dependent FOXM1 Promotes Epithelial-to-Mesenchymal Transition Via Cellular Metabolism and Targeting Snail in Human Pancreatic Cancer.

OBJECTIVES: Transcription factor Forkhead box protein M1 (FOXM1) plays critical roles in the progression of cancer including epithelial-to-mesenchymal transition (EMT). The aim of this study is to characterize the regulatory mechanisms of FOXM1 in EMT via pancreatic cancer metabolism. METHODS: We investigated the regulation of EMT via mitochondrial respiration by FOXM1 using pancreatic cancer cell lines HPAC and PANC-1 and normal human pancreatic duct epithelial cells. RESULTS: Forkhead box protein M1 and Snail were strongly expressed in HPAC and PANC-1. Epithelial-to-mesenchymal transition-modulated claudin-1 level was lower in PANC-1 than in HPAC. In both cell lines in low-glucose medium, FOXM1 and Snail were decreased and claudin-1 was increased. Knockdown of FOXM1 increased claudin-1 and decreased Snail in both cell lines. Low-glucose medium and downregulation of FOXM1 inhibited the cell migration in both cell lines. In both cell lines, mitochondrial respiration was at higher levels in low-glucose medium than in high-glucose medium. Downregulation of FOXM1 induced mitochondrial respiration in high-glucose medium. In normal human pancreatic duct epithelial cells, FOXM1 and Snail were low and claudin-1 was highly expressed, whereas overexpression of FOXM1 decreased claudin-1. CONCLUSIONS: Glucose-dependent FOXM1 promoted EMT via Snail and pancreatic cancer metabolism.

Akt1 signalling supports acinar proliferation and limits acinar-to-ductal metaplasia formation upon induction of acute pancreatitis.

Molecular signalling mediated by the phosphatidylinositol-3-kinase (PI3K)-Akt axis is a key regulator of cellular functions. Importantly, alteration of the PI3K-Akt signalling underlies the development of different human diseases, thus prompting the investigation of the pathway as a molecular target for pharmacologic intervention. In this regard, recent studies showed that small molecule inhibitors of PI3K, the upstream regulator of the pathway, reduced the development of inflammation during acute pancreatitis, a highly debilitating and potentially lethal disease. Here we investigated whether a specific reduction of Akt activity, by using either pharmacologic Akt inhibition, or genetic inactivation of the Akt1 isoform selectively in pancreatic acinar cells, is effective in ameliorating the onset and progression of the disease. We discovered that systemic reduction of Akt activity did not protect the pancreas from initial damage and only transiently delayed leukocyte recruitment. However, reduction of Akt activity decreased acinar proliferation and exacerbated acinar-to-ductal metaplasia (ADM) formation, two critical events in the progression of pancreatitis. These phenotypes were recapitulated upon conditional inactivation of Akt1 in acinar cells, which resulted in reduced expression of 4E-BP1, a multifunctional protein of key importance in cell proliferation and metaplasia formation. Collectively, our results highlight the critical role played by Akt1 during the development of acute pancreatitis in the control of acinar cell proliferation and ADM formation. In addition, these results harbour important translational implications as they raise the concern that inhibitors of PI3K-Akt signalling pathways may negatively affect the regeneration of the pancreas. Finally, this work provides the basis for further investigating the potential of Akt1 activators to boost pancreatic regeneration following inflammatory insults. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Andrographolide promotes pancreatic duct cells differentiation into insulin-producing cells by targeting PDX-1.

Regeneration of ß-cells by differentiation of pancreatic progenitor cells has the potential to fundamentally solve the problems of the loss of ß-cell function and mass during disease progression in both type 1 or 2 diabetes. Therefore, discovery of novel differentiation inducers to promote islet regeneration is of great significance. Pancreatic and duodenal homeobox1 (PDX-1) is a key transcription factor that promotes the development and maturation of pancreatic ß-cells. To screen potential novel small molecules for enhancing differentiation of PNAC-1 cells, a human pancreatic ductal cell lines into insulin-producing cells (IPCs), we developed a high-throughput screening method through fusing the PDX-1 promoter region with a luciferase reporter gene. We screened and identified that andrographolide named C1037 stimulates PDX-1 expression in both mRNA and protein level and significantly promotes PANC-1 cells differentiation into IPCs as compared with that of control cells. The therapeutic effect of C037 in Streptozotocin induced diabetic mouse model through differentiation of pancreatic ductal cells into insulin positive islets was also observed. Our study provides a novel method to screen compounds regulating the differentiation of pancreatic progenitor cells having the potential of enhancing islet regeneration for diabetes therapy.

Preventative Effect of Nafamostat Mesilate Infusion into the Main Pancreatic Duct on Post-ERCP Pancreatitis in a Porcine Model: Initial Pilot Study.

Background and Aim: Post endoscopic retrograde cholangiopancreatography (post-ERCP) pancreatitis is not an uncommon adverse event but may not be avoidable. Various pharmacological and endoscopic techniques have been used to prevent post-ERCP pancreatitis (PEP), but most have been ineffective. The aim of this study was to evaluate the preventative effect of an intrapancreatic duct injection of nafamostat mesilate (NM) on PEP. Methods: This experimental study was conducted on 8 mini pigs. Animals were randomly allocated to a control group (n = 4) and or a NM group (n = 4). Pancreatitis was induced by infusing contrast medium into the main pancreatic duct by ERCP in all animals. After contrast medium injection, NM (50 mg/5 cc) was infused in the NM group and the same amount of 5% dextrose solution was infused in the control group. Twenty-four hours after endoscopic procedures, pancreatic inflammation, edema, vacuolization, necrosis and hemorrhage were evaluated histologically. Results: All animals survived until the end of the experiment. No peri-procedural technical difficulty or adverse event was encountered. Histologic examinations confirmed acute pancreatitis in all animals. In histologic acute pancreatitis scoring, no significant intergroup differences were observed between edema (P = 0.134), leukocyte infiltration (P = 0.356), vacuolization (P = 1.000), or hemorrhage (P = 0.071) scores. However, mean necrosis score was significantly lower in the NM group (1.0) than in controls (1.75, P = 0.024). Conclusion: NM injection into the intrapancreatic duct produced promising results with respect to the prevention of PEP development, especially regarding the prevention of necrosis.

Effects of the Poly(ADP-Ribose) Polymerase Inhibitor Olaparib in Cerulein-Induced Pancreatitis.

OBJECTIVE: Activation of the constitutive nuclear and mitochondrial enzyme poly (ADP-ribose) polymerase (PARP) has been implicated in the pathogenesis of cell dysfunction, inflammation, and organ failure in various forms of critical illness. The objective of our study was to evaluate the efficacy and safety of the clinically approved PARP inhibitor olaparib in an experimental model of pancreatitis in vivo and in a pancreatic cell line subjected to oxidative stress in vitro. The preclinical studies were complemented with analysis of clinical samples to detect PARP activation in pancreatitis. METHODS: Mice were subjected to cerulein-induced pancreatitis; circulating mediators and circulating organ injury markers; pancreatic myeloperoxidase and malondialdehyde levels were measured and histology of the pancreas was assessed. In human pancreatic duct epithelial cells (HPDE) subjected to oxidative stress, PARP activation was measured by PAR Western blotting and cell viability and DNA integrity were quantified. In clinical samples, PARP activation was assessed by PAR (the enzymatic product of PARP) immunohistochemistry. RESULTS: In male mice subjected to pancreatitis, olaparib (3 mg/kg i.p.) improved pancreatic function: it reduced pancreatic myeloperoxidase and malondialdehyde levels, attenuated the plasma amylase levels, and improved the histological picture of the pancreas. It also attenuated the plasma levels of pro-inflammatory mediators (TNF-α, IL-1ß, IL-2, IL-4, IL-6, IL-12, IP-10, KC) but not MCP-1, RANTES, or the anti-inflammatory cytokine IL-10. Finally, it prevented the slight, but significant increase in plasma blood urea nitrogen level, suggesting improved renal function. The protective effect of olaparib was also confirmed in female mice. In HPDE cells subjected to oxidative stress olaparib (1 µM) inhibited PARP activity, protected against the loss of cell viability, and prevented the loss of cellular NAD levels. Olaparib, at 1µM to 30 µM did not have any adverse effects on DNA integrity. In human pancreatic samples from patients who died of pancreatitis, increased accumulation of PAR was demonstrated. CONCLUSION: Olaparib improves organ function and tempers the hyperinflammatory response in pancreatitis. It also protects against pancreatic cell injury in vitro without adversely affecting DNA integrity. Repurposing and eventual clinical introduction of this clinically approved PARP inhibitor may be warranted for the experimental therapy of pancreatitis.

Novel mitochondrial transition pore inhibitor N-methyl-4-isoleucine cyclosporin is a new therapeutic option in acute pancreatitis.

KEY POINTS: •Bile acids, ethanol and fatty acids affect pancreatic ductal fluid and bicarbonate secretion via mitochondrial damage, ATP depletion and calcium overload. •Pancreatitis-inducing factors open the membrane transition pore (mPTP) channel via cyclophilin D activation in acinar cells, causing calcium overload and cell death; genetic or pharmacological inhibition of mPTP improves the outcome of acute pancreatitis in animal models. •Here we show that genetic and pharmacological inhibition of mPTP protects mitochondrial homeostasis and cell function evoked by pancreatitis-inducing factors in pancreatic ductal cells. •The results also show that the novel cyclosporin A derivative NIM811 protects mitochondrial function in acinar and ductal cells, and it preserves bicarbonate transport mechanisms in pancreatic ductal cells. •We found that NIM811 is highly effective in different experimental pancreatitis models and has no side-effects. NIM811 is a highly suitable compound to be tested in clinical trials. ABSTRACT: Mitochondrial dysfunction plays a crucial role in the development of acute pancreatitis (AP); however, no compound is currently available with clinically acceptable effectiveness and safety. In this study, we investigated the effects of a novel mitochondrial transition pore inhibitor, N-methyl-4-isoleucine cyclosporin (NIM811), in AP. Pancreatic ductal and acinar cells were isolated by enzymatic digestion from Bl/6 mice. In vitro measurements were performed by confocal microscopy and microfluorometry. Preventative effects of pharmacological [cylosporin A (2 µm), NIM811 (2 µm)] or genetic (Ppif-/- /Cyp D KO) inhibition of the mitochondrial transition pore (mPTP) during the administration of either bile acids (BA) or ethanol + fatty acids (EtOH+FA) were examined. Toxicity of mPTP inhibition was investigated by detecting apoptosis and necrosis. In vivo effects of the most promising compound, NIM811 (5 or 10 mg kg-1 per os), were checked in three different AP models induced by either caerulein (10 × 50 µg kg-1 ), EtOH+FA (1.75 g kg-1 ethanol and 750 mg kg-1 palmitic acid) or 4% taurocholic acid (2 ml kg-1 ). Both genetic and pharmacological inhibition of Cyp D significantly prevented the toxic effects of BA and EtOH+FA by restoring mitochondrial membrane potential (Δψ) and preventing the loss of mitochondrial mass. In vivo experiments revealed that per os administration of NIM811 has a protective effect in AP by reducing oedema, necrosis, leukocyte infiltration and serum amylase level in AP models. Administration of NIM811 had no toxic effects. The novel mitochondrial transition pore inhibitor NIM811 thus seems to be an exceptionally good candidate compound for clinical trials in AP.

Permanent Pancreatic Duct Occlusion With Neoprene-based Glue Injection After Pancreatoduodenectomy at High Risk of Pancreatic Fistula: A Prospective Clinical Study.

OBJECTIVE: The aim of this study was to assess safety and efficacy of pancreatic duct occlusion (PDO) with neoprene-based glue in selected patients undergoing pancreatoduodenectomy (PD) at high risk of postoperative pancreatic fistula (POPF). BACKGROUND DATA: PD is the reference standard approach for tumors of the pancreaticoduodenal region. POPF is the most relevant complication after PD. PDO has been proposed as an alternative to anastomosis to manage the pancreatic stump. METHODS: A single-center, prospective, nonrandomized trial enrolled 100 consecutive PD for cancer. Patients at high risk for POPF according to Fistula Risk Score (FRS) >15% (≥6 points) were treated with PDO using neoprene glue (study cohort); patients with FRS ≤15% (≤5 points) received pancreaticojejunal anastomosis (PJA: control cohort). Primary endpoint was complication rate grade ≥3 according to Dindo-Clavien Classification (DCC). Other postoperative outcomes were monitored (ClinicalTrials.gov NCT03738787). RESULTS: Fifty-one patients underwent PDO and 49 PJA. DCC ≥3, postoperative mortality, and POPF grade B-C were 25.5% versus 24.5% (P = 0.91), 5.9% versus 2% (P = 0.62), and 11.8% versus 16.3% (P = 0.51) in the study versus control cohort, respectively. At 1 and 3 years, new-onset diabetes was diagnosed in 13.7% and 36.7% of the study cohort versu 4.2% and 12.2% in controls (P = 0.007). CONCLUSIONS: PDO with neoprene-based glue is a safe technique that equalizes early outcome of selected patients at high risk of POPF to those at low risk undergoing PJA. Neoprene-based PDO, however, triples the risk of diabetes at 1 and 3 years.

The antioxidant transcription factor Nrf2 modulates the stress response and phenotype of malignant as well as premalignant pancreatic ductal epithelial cells by inducing expression of the ATF3 splicing variant ΔZip2.

Pancreatic ductal adenocarcinoma (PDAC) exhibits one of the worst survival rates of all cancers. While death rates show declining trends in the majority of cancers, PDAC registers rising rates. Based on the recently described crosstalk between TGF-ß1 and Nrf2 in the PDAC development, the involvement of ATF3 and its splice variant ΔZip2 in TGF-ß1- and Nrf2-driven pancreatic tumorigenesis was investigated. As demonstrated here, PDAC (Panc1, T3M4) cells or premalignant H6c7 pancreatic ductal epithelial cells differentially express ΔZip2- and ATF3, relating to stronger Nrf2 activity seen in Panc1 cells and TGF-ß1 activity in T3M4 or H6c7 cells, respectively. Treatment with the electrophile/oxidative stress inducer tBHQ or the cytostatic drug gemcitabine strongly elevated ΔZip2 expression in a Nrf2-dependent fashion. The differential expression of ATF3 and ΔZip2 in response to Nrf2 and TGF-ß1 relates to differential ATF3-gene promoter usage, giving rise of distinct splice variants. Nrf2-dependent ΔZip2 expression confers resistance against gemcitabine-induced apoptosis, only partially relating to interference with ATF3 and its proapoptotic activity, e.g., through CHOP-expression. In fact, ΔZip2 autonomously activates expression of cIAP anti-apoptotic proteins. Moreover, ΔZip2 favors and ATF3 suppresses growth and clonal expansion of PDAC cells, again partially independent of each other. Using a Panc1 tumor xenograft model in SCID-beige mice, the opposite activities of ATF3 and ΔZip2 on tumor-growth and chemoresistance were verified in vivo. Immunohistochemical analyses confirmed ΔZip2 and Nrf2 coexpression in cancerous and PanIN structures of human PDAC and chronic pancreatitis tissues, respectively, which to some extent was reciprocal to ATF3 expression. It is concluded that depending on selective ATF3-gene promoter usage by Nrf2, the ΔZip2 expression is induced in response to electrophile/oxidative (here through tBHQ) and xenobiotic (here through gemcitabine) stress, providing apoptosis protection and growth advantages to pancreatic ductal epithelial cells. This condition may substantially add to pancreatic carcinogenesis driven by chronic inflammation.

Activated Ductal Proliferation Induced by N-Nitrosobis (2-oxopropyl)amine in Fat-infiltrated Pancreas of KK-Ay Mice.

BACKGROUND/AIM: Our aim was to investigate whether tissue with fatty infiltration within the lobes of the pancreas (scattered FI) is sensitive to carcinogen-induced pancreatic ductal proliferation. MATERIALS AND METHODS: Seven-week-old female C57BL/6J, C57BL/6J-Ay, KK-Ay, and ICR mice were subcutaneously treated with N-nitrosobis(2-oxopropyl) amine at a dose of 80 mg/kg body weight, and the differences in damage-induced cell proliferation and their biochemical data were compared 2 days after. RESULTS: Scattered FI in the pancreas was obvious only in KK-Ay mice, which have high serum lipid, leptin and insulin levels, and cell proliferation both in pancreatic and common bile ducts was enhanced only in KK-Ay mice by the carcinogen treatment. CONCLUSION: Scattered FI in the pancreas per se can be an important factor for carcinogenesis. The genetic background causing scattered FI of the pancreas should be further investigated.

Imaging-based biomarkers: Changes in the tumor interface of pancreatic ductal adenocarcinoma on computed tomography scans indicate response to cytotoxic therapy.

BACKGROUND: The assessment of pancreatic ductal adenocarcinoma (PDAC) response to therapy remains challenging. The objective of this study was to investigate whether changes in the tumor/parenchyma interface are associated with response. METHODS: Computed tomography (CT) scans before and after therapy were reviewed in 4 cohorts: cohort 1 (99 patients with stage I/II PDAC who received neoadjuvant chemoradiation and surgery); cohort 2 (86 patients with stage IV PDAC who received chemotherapy), cohort 3 (94 patients with stage I/II PDAC who received protocol-based neoadjuvant gemcitabine chemoradiation), and cohort 4 (47 patients with stage I/II PDAC who received neoadjuvant chemoradiation and were prospectively followed in a registry). The tumor/parenchyma interface was visually classified as either a type I response (the interface remained or became well defined) or a type II response (the interface became poorly defined) after therapy. Consensus (cohorts 1-3) and individual (cohort 4) visual scoring was performed. Changes in enhancement at the interface were quantified using a proprietary platform. RESULTS: In cohort 1, type I responders had a greater probability of achieving a complete or near-complete pathologic response (21% vs 0%; P = .01). For cohorts 1, 2, and 3, type I responders had significantly longer disease-free and overall survival, independent of traditional covariates of outcomes and of baseline and normalized cancer antigen 19-9 levels. In cohort 4, 2 senior radiologists achieved a κ value of 0.8, and the interface score was associated with overall survival. The quantitative method revealed high specificity and sensitivity in classifying patients as type I or type II responders (with an area under the receiver operating curve of 0.92 in cohort 1, 0.96 in cohort 2, and 0.89 in cohort 3). CONCLUSIONS: Changes at the PDAC/parenchyma interface may serve as an early predictor of response to therapy. Cancer 2018;124:1701-9. © 2018 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Metformin suppresses cancer initiation and progression in genetic mouse models of pancreatic cancer.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-associated mortality worldwide with an overall five-year survival rate less than 7%. Accumulating evidence has revealed the cancer preventive and therapeutic effects of metformin, one of the most widely prescribed medications for type 2 diabetes mellitus. However, its role in pancreatic cancer is not fully elucidated. Herein, we aimed to further study the preventive and therapeutic effects of metformin in genetically engineered mouse models of pancreatic cancer. METHODS: LSL-KrasG12D/+; Pdx1-Cre (KC) mouse model was established to investigate the effect of metformin in pancreatic tumorigenesis suppression; LSL-KrasG12D/+; Trp53fl/+; Pdx1-Cre (KPC) mouse model was used to evaluate the therapeutic efficiency of metformin in PDAC. Chronic pancreatitis was induced in KC mice by peritoneal injection of cerulein. RESULTS: Following metformin treatment, pancreatic acinar-to-ductal metaplasia (ADM) and mouse pancreatic intraepithelial neoplasia (mPanIN) were decreased in KC mice. Chronic pancreatitis induced a stroma-rich and duct-like structure and increased the formation of ADM and mPanIN lesions, in line with an increased cytokeratin 19 (CK19)-stained area. Metformin treatment diminished chronic pancreatitis-mediated ADM and mPanIN formation. In addition, it alleviated the percent area of Masson's trichrome staining, and decreased the number of Ki67-positive cells. In KPC mice, metformin inhibited tumor growth and the incidence of abdominal invasion. More importantly, it prolonged the overall survival. CONCLUSIONS: Metformin inhibited pancreatic cancer initiation, suppressed chronic pancreatitis-induced tumorigenesis, and showed promising therapeutic effect in PDAC.

Pancreatic Ductal Adenocarcinoma: Current and Evolving Therapies.

Pancreatic ductal adenocarcinoma (PDAC), which constitutes 90% of pancreatic cancers, is the fourth leading cause of cancer-related deaths in the world. Due to the broad heterogeneity of genetic mutations and dense stromal environment, PDAC belongs to one of the most chemoresistant cancers. Most of the available treatments are palliative, with the objective of relieving disease-related symptoms and prolonging survival. Currently, available therapeutic options are surgery, radiation, chemotherapy, immunotherapy, and use of targeted drugs. However, thus far, therapies targeting cancer-associated molecular pathways have not given satisfactory results; this is due in part to the rapid upregulation of compensatory alternative pathways as well as dense desmoplastic reaction. In this review, we summarize currently available therapies and clinical trials, directed towards a plethora of pathways and components dysregulated during PDAC carcinogenesis. Emerging trends towards targeted therapies as the most promising approach will also be discussed.