Effect of High Fructose Corn Sirup on Pancreatic Ductal Adenocarcinoma Induced by Dimethyl Benzantracene (DMBA) in Rats.

Increased risk of pancreatic cancer may be associated with consumption of sugar containing foods. The aim of this study was to evaluate the effect of peach nectar containing high fructose corn sirup (HFCS) consumption in a pancreatic carcinogenesis rat model induced by 7,12-Dimethyl benzanthracene (DMBA). Fifty-day-old male Sprague Dawley rats were fed with peach nectar containing HFCS + chow, peach nectar containing sucrose + chow and only chow. After 8 mo, feeding period, each group was divided into two subgroups, in which the rats were implanted with DMBA and no DMBA (sham). Histologic specimens were evaluated according to the routine tissue processing protocol. The animals with ad libitum access to pn-HFCS, pn-sucrose and chow (only) showed significant differences in chow consumption and glucose level. Necropsy and histopathologic findings showed tumor formation in the entire group treated with DMBA. Excluding one rat in chow group, which was classified as poorly differentiated type, the others were classified as moderately differentiated pancreatic ductal adenocarcinoma (PDAC). This study demonstrated that daily intake of HFCS did not increase body weight and there was no effect of peach nectar consumption on the development of PDAC induced by DMBA in rats.

Bile accelerates carcinogenic processes in pancreatic ductal adenocarcinoma cells through the overexpression of MUC4.

Pancreatic cancer (PC) is one of the leading causes of mortality rate globally and is usually associated with obstructive jaundice (OJ). Up to date, there is no clear consensus on whether biliary decompression should be performed prior to surgery and how high levels of serum bile affects the outcome of PC. Therefore, our study aims were to characterise the effect of bile acids (BAs) on carcinogenic processes using pancreatic ductal adenocarcinoma (PDAC) cell lines and to investigate the underlying mechanisms. Liquid chromatography-mass spectrometry was used to determine the serum concentrations of BAs. The effects of BAs on tumour progression were investigated using different assays. Mucin expressions were studied in normal and PDAC cell lines and in human samples at gene and protein levels and results were validated with gene silencing. The levels of BAs were significantly higher in the PDAC + OJ group compared to the healthy control. Treating PDAC cells with different BAs or with human serum obtained from PDAC + OJ patients enhanced the rate of proliferation, migration, adhesion, colony forming, and the expression of MUC4. In PDAC + OJ patients, MUC4 expression was higher and the 4-year survival rate was lower compare to PDAC patients. Silencing of MUC4 decreased BAs-induced carcinogenic processes in PDAC cells. Our results show that BAs promote carcinogenic process in PDAC cells, in which the increased expression of MUC4 plays an important role. Based on these results, we assume that in PC patients, where the disease is associated with OJ, the early treatment of biliary obstruction improves life expectancy.

The synergistic tumor growth-inhibitory effect of probiotic Lactobacillus on transgenic mouse model of pancreatic cancer treated with gemcitabine.

Pancreatic cancer is one of the most lethal and chemo-resistant cancers worldwide. Growing evidence supports the theory that the gut microbiota plays an essential role in modulating the host response to anti-cancer therapy. The present study aimed to explore the effect of probiotics as an adjuvant during chemotherapy for pancreatic cancer. An LSL-KrasG12D/--Pdx-1-Cre mouse model of pancreatic ductal adenocarcinoma (PDAC) was created to study the effects of using four-week multi-strain probiotics (Lactobacillus paracasei GMNL-133 and Lactobacillus reuteri GMNL-89) as an adjuvant therapy for controlling cancer progression. At 12 weeks of age, pancreatitis was induced in the mice by two intraperitoneal injection with caerulein (25 µg/kg 2 days apart). Over the next 4 weeks the mice were treated with intraperitoneal injections of gemcitabine in combination with the oral administration of probiotics. The pancreas was then harvested for analysis. Following caerulein treatment, the pancreases of the LSL-KrasG12D/--Pdx-1-Cre transgenic mice exhibited more extensive pancreatic intraepithelial neoplasia (PanIN) formation. Combined treatment with gemcitabine and probiotics revealed a lower grade of PanIN formation and a decrease in the expression of vimentin and Ki-67. Mice that received gemcitabine in combination with probiotics had lower aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Notably, the use of high-dose probiotics alone without gemcitabine also had an inhibitory effect on PanIN changes and serum liver enzyme elevation. These findings suggest that probiotics are able to make standard chemotherapy more effective and could help improve the patient's tolerance of chemotherapy.

The Diverse Involvement of Cigarette Smoking in Pancreatic Cancer Development and Prognosis.

Despite extensive research in the pathogenesis, early detection, and therapeutic approaches of pancreatic ductal adenocarcinoma (PDAC), it remains a devastating and incurable disease. As the global incidence and prevalence of PDAC continue to rise, there is a pressing need to place strong emphasis on its prevention. Although it is widely recognized that cigarette smoking, a potentially modifiable risk factor, has been linked to PDAC development, its contribution to prognosis is still uncertain. Moreover, the mechanistic pathways of PDAC progression secondary to smoking are various and lack a summative narration. Herein, we update and summarize the direct and indirect roles cigarette smoking plays on PDAC development, review literature to conclude the impact cigarette smoking has on prognosis, and postulate a comprehensive mechanism for cigarette smoking-induced PDAC.

A Diabetic Patient Complicated With Pancreatic Cancer After Using Liraglutide: A Case Report.

Background: Diabetes and cancer are both multifactorial diseases, and epidemiologic evidence indicates that diabetes may be associated with the incidence of certain types of cancer. In diabetes the risk of pancreatic cancer is increased significantly. However, whether certain diabetes treatment being related with the risk of pancreatic cancer remains unclear. In this report, we presented a case of pancreatic ductal adenocarcinoma in a diabetic patient in China after being treated with liraglutide, a novel glucagon-like peptide-1 (GLP-1) analog. Case report: A 71-year-old Han Chinese man who had had a type 2 diabetes for 25 years presented at the endocrinology department with discomfort in the left upper quadrant of abdomen for 10 days. The patient's vital signs and laboratory findings were unremarkable except for the elevated level of carbohydrate antigen (CA19-9). The upper abdomen routine enhanced computed tomography (CT) scan showed low density of the pancreatic body and tail, and the histopathological result of the pancreatic biopsy samples was pancreatic ductal adenocarcinoma with regional lymph node metastasis. We reviewed his former medical records and found that liraglutide was added to his hypoglycemic treatment regimen 20 months ago. At that time, the level of tumor biomarkers and upper abdomen routine CT were unremarkable. We estimated the causality between liraglutide and pancreatic cancer by the Naranjo Adverse Drug Reaction Probability scale and WHO-Uppsala Monitoring Centre (WHO-UMC) system, and the causality turned out to be possible. Conclusion: Our report suggests that liraglutide may be related with the genesis and development of pancreatic cancer and also highlights the importance of regular checkups in diabetic patients treated with liraglutide. However, our report has some notable limitations, and further longer-term follow-up trials with larger sample should be conducted in future to assess the causality between liraglutide and pancreatic cancer.

Moderate alcohol intake promotes pancreatic ductal adenocarcinoma development in mice expressing oncogenic Kras.

Kras mutations are associated with pancreatic ductal adenocarcinoma (PDAC). Although tobacco smoking, pancreatitis, and obesity are known environmental risk factors for PDAC, the contribution of moderate alcohol intake to PDAC remains elusive. In the present study, we tested whether a combination of risk factors or moderate alcohol intake induces PDAC development in mice. Control Pdx1Cre and Pdx1Cre;LSL-KrasG12D mutant mice were fed a Western alcohol diet containing high levels of cholesterol and saturated fat, 3.5% alcohol, and lipopolysaccharide for 5 mo. In addition, mice were treated with cerulein, for induction of pancreatitis, and nicotine every month. Treatment with all of these risk factors promoted development of advanced pancreatic neoplasia and PDAC in the Pdx1Cre;LSL-KrasG12D mice but not in the control Pdx1Cre mice. Moderate alcohol intake or Western diet feeding also significantly promoted advanced neoplasia and PDAC development in Pdx1Cre;LSL-KrasG12D mice compared with mice fed a regular chow. Alcohol, but not Western diet, increased tumor development in the liver in the Pdx1Cre;LSL-KrasG12D mice, but its origin remained elusive due to leakiness of Pdx1Cre in hepatocytes. RNA-seq analysis revealed that alcohol feeding increases expression of markers for tumors (Epcam, Krt19, Prom1, Wt1, and Wwtr1), stroma (Dcn, Fn1, and Tnc), and cytokines (Tgfb1 and Tnf) and decreases expression of Fgf21 and Il6 in the pancreatic tumor tissues. Immunostaining showed heterogeneous expression of nephronectin, S100 calcium-binding protein A6, and vascular cell adhesion molecule 1 in pancreatic tumors surrounded by podoplanin-positive stromal cells. Our data indicate that moderate alcohol drinking is a risk factor for development of PDAC.NEW & NOTEWORTHY Heavy alcohol intake has been suspected to be a risk factor of pancreatic ductal adenocarcinoma (PDAC) in humans. However, the contribution of moderate alcohol intake to PDAC development remains elusive. In the present study, we experimentally show that moderate alcohol feeding significantly induces advanced stages of pancreatic intraepithelial neoplasia development and invasive PDAC in Pdx1Cre;LSL-KrasG12D mutant mice. Our data indicate that moderate alcohol drinking is a risk factor for PDAC.

High Glucose Triggers Nucleotide Imbalance through O-GlcNAcylation of Key Enzymes and Induces KRAS Mutation in Pancreatic Cells.

KRAS mutations are the earliest events found in approximately 90% of pancreatic ductal adenocarcinomas (PDACs). However, little is known as to why KRAS mutations preferentially occur in PDACs and what processes/factors generate these mutations. While abnormal carbohydrate metabolism is associated with a high risk of pancreatic cancer, it remains elusive whether a direct relationship between KRAS mutations and sugar metabolism exists. Here, we show that under high-glucose conditions, cellular O-GlcNAcylation is significantly elevated in pancreatic cells that exhibit lower phosphofructokinase (PFK) activity than other cell types. This post-translational modification specifically compromises the ribonucleotide reductase (RNR) activity, leading to deficiency in dNTP pools, genomic DNA alterations with KRAS mutations, and cellular transformation. These results establish a mechanistic link between a perturbed sugar metabolism and genomic instability that induces de novo oncogenic KRAS mutations preferentially in pancreatic cells.

Atypical flat lesions derive from pancreatic acinar cells.

OBJECTIVES: Pancreatic ductal adenocarcinoma (PDAC) is thought to derive from different precursor lesions including the recently identified atypical flat lesions (AFL). While all precursor lesions and PDAC share ductal characteristics, there is an ongoing debate about the cellular origin of the different PDAC precursor lesions. In particular, pancreatic acinar cells have previously been shown to display a remarkable plasticity being able to undergo ductal dedifferentiation in the context of oncogenic stimuli. METHODS: Histological analyses were performed in a murine PDAC model that specifically expresses oncogenic Kras in adult pancreatic acinar cells. Occurrence, characterization, and lineage tracing of AFLs were investigated. RESULTS: Upon expression of oncogenic Kras in adult pancreatic acinar cells, AFLs with typical morphology and expression profile arise. Lineage tracing confirmed that the AFLs were of acinar origin. CONCLUSIONS: Using a murine PDAC model, this study identifies pancreatic acinar cells as a cellular source for AFLs.

Dclk1 Defines Quiescent Pancreatic Progenitors that Promote Injury-Induced Regeneration and Tumorigenesis.

The existence of adult pancreatic progenitor cells has been debated. While some favor the concept of facultative progenitors involved in homeostasis and repair, neither a location nor markers for such cells have been defined. Using genetic lineage tracing, we show that Doublecortin-like kinase-1 (Dclk1) labels a rare population of long-lived, quiescent pancreatic cells. In vitro, Dclk1+ cells proliferate readily and sustain pancreatic organoid growth. In vivo, Dclk1+ cells are necessary for pancreatic regeneration following injury and chronic inflammation. Accordingly, their loss has detrimental effects after cerulein-induced pancreatitis. Expression of mutant Kras in Dclk1+ cells does not affect their quiescence or longevity. However, experimental pancreatitis converts Kras mutant Dclk1+ cells into potent cancer-initiating cells. As a potential effector of Kras, Dclk1 contributes functionally to the pathogenesis of pancreatic cancer. Taken together, these observations indicate that Dclk1 marks quiescent pancreatic progenitors that are candidates for the origin of pancreatic cancer.

HDAC3 mediates smoking-induced pancreatic cancer.

Smoking is a major risk factor for developing pancreatic adenocarcinoma (PDAC); however, little is known about the mechanisms involved. Here we employed a genetic animal model of early stages of PDAC that overexpresses oncogenic Kras in the pancreas to investigate the mechanisms of smoking-induced promotion of the disease in vivo. We confirmed the regulation of the interactions between the tumor microenvironment cells using in vitro cellular systems. Aerial exposure to cigarette smoke stimulated development of pancreatic intraepithelial neaoplasia (PanIN) lesions associated with a tumor microenvironment-containing features of human PDAC including fibrosis, activated stellate cells, M2-macrophages and markers of epithelial-mesenchymal transition (EMT). The pro-cancer effects of smoking were prevented by Histone Deacetylase HDAC I/II inhibitor Saha. Smoking decreased histone acetylation associated with recruitment of and phenotypic changes in macrophages; which in turn, stimulated survival and induction of EMT of the pre-cancer and cancer cells. The interaction between the cancer cells and macrophages is mediated by IL-6 produced under the regulation of HDAC3 translocation to the nucleus in the cancer cells. Pharmacological and molecular inhibitions of HDAC3 decreased IL-6 levels in cancer cells. IL-6 stimulated the macrophage phenotype change through regulation of the IL-4 receptor level of the macrophage. This study demonstrates a novel pathway of interaction between cancer cells and tumor promoting macrophages involving HDAC3 and IL-6. It further demonstrates that targeting HDAC3 prevents progression of the disease and could provide a strategy for treating the disease considering that the HDAC inhibitor we used is FDA approved for a different disease.

Orthotopic inflammation-related pancreatic carcinogenesis in a wild-type mouse induced by combined application of caerulein and dimethylbenzanthracene.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human malignancies, with a poor long-term prognosis, and effective therapeutic options are lacking. Observing the dynamics of the pathogenesis of pancreatic intraepithelial neoplasia (PanIN) and PDAC in tumor models can facilitate understanding of the molecular mechanisms involved in early PDAC. Furthermore, it can compensate for the research limitations associated with analyzing clinical specimens of late-stage PDAC. In this study, we orthotopically treated the pancreas with dimethylbenzanthracene (DMBA) combined with caerulein in wild-type C57BL/6 J mice to induce inflammation-related pancreatic carcinogenesis. We observed that DMBA and caerulein treatment induced a chronic consumptive disease, which caused a decrease in the relative body and pancreas weights, diminishing the health status of the mice and enhancing the inflammation-related histological changes. Moreover, mid-dose and high-frequency treatment with caerulein caused prolonged inflammatory damage to the pancreas and contributed to a permissive environment for the development of PDAC. CXCL12/CXCR4, CCL2/CCR2, and several cytokines, such as interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α were upregulated in the tumor tissue of DMBA and caerulein-induced PDAC mice. This orthotopic mouse pancreatic carcinogenesis model mimic human disease because it reproduces a spectrum of pathological changes observed in human PDAC, ranging from inflammatory lesions to pancreatic intraepithelial neoplasia. Thus, this mouse model may improve the understanding of molecular mechanisms underlying the injury-inflammation-cancer pathway in the early stages of pancreatic carcinogenesis.

NFATc1 Links EGFR Signaling to Induction of Sox9 Transcription and Acinar-Ductal Transdifferentiation in the Pancreas.

BACKGROUND & AIMS: Oncogenic mutations in KRAS contribute to the development of pancreatic ductal adenocarcinoma, but are not sufficient to initiate carcinogenesis. Secondary events, such as inflammation-induced signaling via the epidermal growth factor receptor (EGFR) and expression of the SOX9 gene, are required for tumor formation. Herein we sought to identify the mechanisms that link EGFR signaling with activation of SOX9 during acinar-ductal metaplasia, a transdifferentiation process that precedes pancreatic carcinogenesis. METHODS: We analyzed pancreatic tissues from Kras(G12D);pdx1-Cre and Kras(G12D);NFATc1(Δ/Δ);pdx1-Cre mice after intraperitoneal administration of caerulein, vs cyclosporin A or dimethyl sulfoxide (controls). Induction of EGFR signaling and its effects on the expression of Nuclear factor of activated T cells c1 (NFATc1) or SOX9 were investigated by quantitative reverse-transcription polymerase chain reaction, immunoblot, and immunohistochemical analyses of mouse and human tissues and acinar cell explants. Interactions between NFATc1 and partner proteins and effects on DNA binding or chromatin modifications were studied using co-immunoprecipitation and chromatin immunoprecipitation assays in acinar cell explants and mouse tissue. RESULTS: EGFR activation induced expression of NFATc1 in metaplastic areas from patients with chronic pancreatitis and in pancreatic tissue from Kras(G12D) mice. EGFR signaling also promoted formation of a complex between NFATc1 and C-JUN in dedifferentiating mouse acinar cells, leading to activation of Sox9 transcription and induction of acinar-ductal metaplasia. Pharmacologic inhibition of NFATc1 or disruption of the Nfatc1 gene inhibited EGFR-mediated induction of Sox9 transcription and blocked acinar-ductal transdifferentiation and pancreatic cancer initiation in mice. CONCLUSIONS: EGFR signaling induces expression of NFATc1 and Sox9, leading to acinar cell transdifferentiation and initiation of pancreatic cancer. Strategies designed to disrupt this pathway might be developed to prevent pancreatic cancer initiation in high-risk patients with chronic pancreatitis.

Biphasic Alterations in Expression and Subcellular Localization of MUC1 in Pancreatic Ductal Carcinogenesis in Syrian Hamsters.

OBJECTIVES: The aim of the present study was to characterize molecular targets for the prevention/diagnosis of pancreatic cancer using a chemically induced hamster pancreatic carcinogenesis model, in which background injuries to the parenchyma, for example, chronic pancreatitis or acinar atrophy, are limited. METHODS: Gene expression profiles in atypical hyperplasias were first investigated using a microarray technique. Immunohistochemical analyses of early lesions and invasive ductal carcinoma (IDC) were then conducted for MUC1, of which mRNA levels were prominent among the up-regulated genes, in contrast with the coexpression of epithelial-mesenchymal transition (EMT)-related proteins. RESULTS: Immunohistochemistry for MUC1 cytoplasmic domain (MUC1-CD), which was not detected in normal-like pancreatic ducts, was positive in the apical surfaces of the epithelia of hyperplasias with and without atypia and IDC areas with distinct tubular patterns. In contrast, cytoplasmic/nuclear positivity for MUC1-CD was observed in the invasive front of IDCs. The coexpression of EMT-related proteins, such as slug and vimentin, with cytoplasmic/nuclear MUC1-CD was also detected. CONCLUSIONS: Alterations in the expression and subcellular localization of MUC1 represent a biphasic phenomenon, and the latter may be associated with EMT in pancreatic carcinogenesis in hamsters, which indicates that changes in MUC1 are important targets for pancreatic cancer prevention and chemotherapy.

Nicotine promotes initiation and progression of KRAS-induced pancreatic cancer via Gata6-dependent dedifferentiation of acinar cells in mice.

BACKGROUND & AIMS: Although smoking is a leading risk factor for pancreatic ductal adenocarcinoma (PDAC), little is known about the mechanisms by which smoking promotes initiation or progression of PDAC. METHODS: We studied the effects of nicotine administration on pancreatic cancer development in Kras(+/LSLG12Vgeo);Elas-tTA/tetO-Cre (Ela-KRAS) mice, Kras(+/LSLG12D);Trp53+/LSLR172H;Pdx-1-Cre (KPC) mice (which express constitutively active forms of KRAS), and C57/B6 mice. Mice were given nicotine for up to 86 weeks to produce blood levels comparable with those of intermediate smokers. Pancreatic tissues were collected and analyzed by immunohistochemistry and reverse transcriptase polymerase chain reaction; cells were isolated and assayed for colony and sphere formation and gene expression. The effects of nicotine were also evaluated in primary pancreatic acinar cells isolated from wild-type, nAChR7a(-/-), Trp53(-/-), and Gata6(-/-);Trp53(-/-) mice. We also analyzed primary PDAC cells that overexpressed GATA6 from lentiviral expression vectors. RESULTS: Administration of nicotine accelerated transformation of pancreatic cells and tumor formation in Ela-KRAS and KPC mice. Nicotine induced dedifferentiation of acinar cells by activating AKT-ERK-MYC signaling; this led to inhibition of Gata6 promoter activity, loss of GATA6 protein, and subsequent loss of acinar differentiation and hyperactivation of oncogenic KRAS. Nicotine also promoted aggressiveness of established tumors as well as the epithelial-mesenchymal transition, increasing numbers of circulating cancer cells and their dissemination to the liver, compared with mice not exposed to nicotine. Nicotine induced pancreatic cells to acquire gene expression patterns and functional characteristics of cancer stem cells. These effects were markedly attenuated in K-Ras(+/LSL-G12D);Trp53(+/LSLR172H);Pdx-1-Cre mice given metformin. Metformin prevented nicotine-induced pancreatic carcinogenesis and tumor growth by up-regulating GATA6 and promoting differentiation toward an acinar cell program. CONCLUSIONS: In mice, nicotine promotes pancreatic carcinogenesis and tumor development via down-regulation of Gata6 to induce acinar cell dedifferentiation.

Epigenetic reprogramming in Mist1(-/-) mice predicts the molecular response to cerulein-induced pancreatitis.

Gene expression is affected by modifications to histone core proteins within chromatin. Changes in these modifications, or epigenetic reprogramming, can dictate cell fate and promote susceptibility to disease. The goal of this study was to determine the extent of epigenetic reprogramming in response to chronic stress that occurs following ablation of MIST1 (Mist1(-/-) ), which is repressed in pancreatic disease. Chromatin immunoprecipitation for trimethylation of lysine residue 4 on histone 3 (H3K4Me3) in purified acinar cells from wild type and Mist1(-/-) mice was followed by Next Generation sequencing (ChIP-seq) or ChIP-qPCR. H3K4Me3-enriched genes were assessed for expression by qRT-PCR in pancreatic tissue before and after induction of cerulein-induced pancreatitis. While most of H3K4Me3-enrichment is restricted to transcriptional start sites, >25% of enrichment sites are found within, downstream or between annotated genes. Less than 10% of these sites were altered in Mist1(-/-) acini, with most changes in H3K4Me3 enrichment not reflecting altered gene expression. Ingenuity Pathway Analysis of genes differentially-enriched for H3K4Me3 revealed an association with pancreatitis and pancreatic ductal adenocarcinoma in Mist1(-/-) tissue. Most of these genes were not differentially expressed but several were readily induced by acute experimental pancreatitis, with significantly increased expression in Mist1(-/-) tissue relative to wild type mice. We suggest that the chronic cell stress observed in the absence of MIST1 results in epigenetic reprogramming of genes involved in promoting pancreatitis to a poised state, thereby increasing the sensitivity to events that promote disease.

Dietary intake of acrylamide and pancreatic cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.

BACKGROUND: In 1994, acrylamide (AA) was classified as a probable human carcinogen by the International Agency for Research on Cancer. In 2002, AA was discovered at relatively high concentrations in some starchy, plant-based foods cooked at high temperatures. PATIENTS AND METHODS: A prospective analysis was conducted to evaluate the association between the dietary intake of AA and ductal adenocarcinoma of the exocrine pancreatic cancer (PC) risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort using Cox regression modeling. EPIC includes >500,000 men and women aged 35-75 at enrollment from 10 European countries. AA intake was estimated for each participant by combining questionnaire-based food consumption data with a harmonized AA database derived from the EU monitoring database of AA levels in foods, and evaluated in quintiles and continuously. RESULTS: After a mean follow-up of 11 years, 865 first incident adenocarcinomas of the exocrine pancreas were observed and included in the present analysis. At baseline, the mean dietary AA intake in EPIC was 26.22 µg/day. No overall association was found between continuous or quintiles of dietary AA intake and PC risk in EPIC (HR:0.95, 95%CI:0.89-1.01 per 10 µg/day). There was no effect measure modification by smoking status, sex, diabetes, alcohol intake or geographic region. However, there was an inverse association (HR: 0.73, 95% CI: 0.61-0.88 per 10 µg/day) between AA intake and PC risk in obese persons as defined using the body mass index (BMI, ≥ 30 kg/m(2)), but not when body fatness was defined using waist and hip circumference or their ratio. CONCLUSIONS: Dietary intake of AA was not associated with an increased risk of PC in the EPIC cohort.

Nicotine/cigarette smoke promotes metastasis of pancreatic cancer through α7nAChR-mediated MUC4 upregulation.

Despite evidence that long-term smoking is the leading risk factor for pancreatic malignancies, the underlying mechanism(s) for cigarette-smoke (CS)-induced pancreatic cancer (PC) pathogenesis has not been well established. Our previous studies revealed an aberrant expression of the MUC4 mucin in PC as compared with the normal pancreas, and its association with cancer progression and metastasis. Interestingly, here we explore a potential link between MUC4 expression and smoking-mediated PC pathogenesis and report that both cigarette smoke extract and nicotine, which is the major component of CS, significantly upregulates MUC4 in PC cells. This nicotine-mediated MUC4 overexpression was via the α7 subunit of nicotinic acetylcholine receptor (nAChR) stimulation and subsequent activation of the JAK2/STAT3 downstream signaling cascade in cooperation with the MEK/ERK1/2 pathway; this effect was blocked by the α7nAChR antagonists, α-bungarotoxin and mecamylamine, and by specific siRNA-mediated STAT3 inhibition. In addition, we demonstrated that nicotine-mediated MUC4 upregulation promotes the PC cell migration through the activation of the downstream effectors, such as HER2, c-Src and FAK; this effect was attenuated by shRNA-mediated MUC4 abrogation, further implying that these nicotine-mediated pathological effects on PC cells are MUC4 dependent. Furthermore, the in vivo studies showed a marked increase in the mean pancreatic tumor weight (low dose (100 mg/m(3) total suspended particulate (TSP)), P=0.014; high dose (247 mg/m(3) TSP), P=0.02) and significant tumor metastasis to various distant organs in the CS-exposed mice, orthotopically implanted with luciferase-transfected PC cells, as compared with the sham controls. Moreover, the CS-exposed mice had elevated levels of serum cotinine (low dose, 155.88±35.96 ng/ml; high dose, 216.25±29.95 ng/ml) and increased MUC4, α7nAChR and pSTAT3 expression in the pancreatic tumor tissues. Altogether, our findings revealed for the first time that CS upregulates the MUC4 mucin in PC via the α7nAChR/JAK2/STAT3 downstream signaling cascade, thereby promoting metastasis of PC.

Long-term in vitro culture of hamster pancreatic ß-cells and induction of adenocarcinoma by treatment with N-nitrosobis(2-oxopropyl)amine.

OBJECTIVES: Earlier studies indicated that hamster pancreatic ductal adenocarcinoma not only derives from ductal/ductular structures but also from cells within the islet. So far unidentified cells within the islet are responsive to the carcinogenic effect of N-nitrosobis (2-oxopropyl) amine (BOP) forming poorly differentiated ductal adenocarcinoma. However, studies indicated a major role of ß-cells during carcinogenesis. To find out, if ß-cells are the primary target cells of BOP and if they are capable to form ductal adenocarcinoma after malignant transformation, we established a long-term culture of undifferentiated cells deriving from isolated ß-cells and treated them with BOP. METHODS: Langerhans' islets from pancreata of Syrian golden hamsters were isolated and dispersed into single cells by dispase digestion. Cells were labeled with a highly specific ß-cell surface antibody (K14D10) and these K14D10+ cells were extracted from the suspension by paramagnetic Dynabeads. Cells were cultured in vitro and treated with BOP. Untreated cells served as control. RESULTS: K14D10+ cells formed a monolayer and produced insulin over a period of 28 days in culture. However, with time in culture they became undifferentiated with a higher proliferation rate and after about 60 days in culture BOP treated cells showed anchorage independent growth. These cells autotransplanted s.c. formed a well-differentiated ductal adenocarcinoma. CONCLUSIONS: Pancreatic ß-cells are the primary target of BOP without necessarily being embedded in the compound of the Langerhans' islet. With time in culture, they give rise to undifferentiated cells and after malignant transformation they are able to form ductal adenocarcinoma.