Human Ductal Cells Research Articles

Single-nucleus RNA-Seq reveals singular gene signatures of human ductal cells during adaptation to insulin resistance.

Adaptation to increased insulin demand is mediated by β cell proliferation and neogenesis, among other mechanisms. Although it is known that pancreatic β cells can arise from ductal progenitors, these observations have been limited mostly to the neonatal period. We have recently reported that the duct is a source of insulin-secreting cells in adult insulin-resistant states. To further explore the signaling pathways underlying the dynamic β cell reserve during insulin resistance, we undertook human islet and duct transplantations under the kidney capsule of immunodeficient NOD/SCID-γ (NSG) mouse models that were pregnant, were insulin-resistant, or had insulin resistance superimposed upon pregnancy (insulin resistance + pregnancy), followed by single-nucleus RNA-Seq (snRNA-Seq) on snap-frozen graft samples. We observed an upregulation of proliferation markers (e.g., NEAT1) and expression of islet endocrine cell markers (e.g., GCG and PPY), as well as mature β cell markers (e.g., INS), in transplanted human duct grafts in response to high insulin demand. We also noted downregulation of ductal cell identity genes (e.g., KRT19 and ONECUT2) coupled with upregulation of β cell development and insulin signaling pathways. These results indicate that subsets of ductal cells are able to gain β cell identity and reflect a form of compensation during the adaptation to insulin resistance in both physiological and pathological states.

Single-cell transcriptome analysis defines heterogeneity of the murine pancreatic ductal tree.

To study disease development, an inventory of an organ's cell types and understanding of physiologic function is paramount. Here, we performed single-cell RNA-sequencing to examine heterogeneity of murine pancreatic duct cells, pancreatobiliary cells, and intrapancreatic bile duct cells. We describe an epithelial-mesenchymal transitory axis in our three pancreatic duct subpopulations and identify osteopontin as a regulator of this fate decision as well as human duct cell dedifferentiation. Our results further identify functional heterogeneity within pancreatic duct subpopulations by elucidating a role for geminin in accumulation of DNA damage in the setting of chronic pancreatitis. Our findings implicate diverse functional roles for subpopulations of pancreatic duct cells in maintenance of duct cell identity and disease progression and establish a comprehensive road map of murine pancreatic duct cell, pancreatobiliary cell, and intrapancreatic bile duct cell homeostasis.

Human duct cells contribute to β cell compensation in insulin resistance.

The identification of new sources of β cells is an important endeavor with therapeutic implications for diabetes. Insulin resistance, in physiological states such as pregnancy or in pathological states such as type 2 diabetes (T2D), is characterized by a compensatory increase in β cell mass. To explore the existence of a dynamic β cell reserve, we superimposed pregnancy on the liver-specific insulin receptor-KO (LIRKO) model of insulin resistance that already exhibits β cell hyperplasia and used lineage tracing to track the source of new β cells. Although both control and LIRKO mice displayed increased β cell mass in response to the relative insulin resistance of pregnancy, the further increase in mass in the latter supported a dynamic source that could be traced to pancreatic ducts. Two observations support the translational significance of these findings. First, NOD/SCID-γ LIRKO mice that became pregnant following cotransplantation of human islets and human ducts under the kidney capsule showed enhanced β cell proliferation and an increase in ductal cells positive for transcription factors expressed during β cell development. Second, we identified duct cells positive for immature β cell markers in pancreas sections from pregnant humans and in individuals with T2D. Taken together, during increased insulin demand, ductal cells contribute to the compensatory β cell pool by differentiation/neogenesis.

Effect of microRNA-19b on proliferation, migration and invasion of pancreatic ductal adenocarcinoma

Objective To examine the expression of microRNA (miRNA, miR)-19b in pancreatic ductal adenocarcinoma (PDAC) cell lines, and the functional role of miR-19b in proliferation, migration and invasion of PDAC cells. Methods Real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) was used to detect the expression level of miR-19b in human pancreatic ductal epithelial cell line (HPDE), human PDAC cell lines (PANC1, MiaPaCa2 and BxPC3) and huamn PDAC metastasis cell line (COLO357) and its fast-growing variant FG. The expression of miR-19b was inhibited or overexpressed in PDAC cell lines. Transwell assay and Matrigel assay were carried out to examine the migration and invasion capabities of PDAC cells with miR-19b silencing or overexpressing. Methyl thiazol tetrazolium (MTT) and colony formation assays were performed on PDAC cell lines with miR-19b silencing or overexpression. Western blotting was used to detect the expression of proliferation markers (p21 and p27) in PDAC cell lines after miR-19b was silenced or overexpressed. Results The results of RT-qPCR showed the expression level of miR-19b in human PDAC cell lines PANC1, MiaPaCa2, BxPC3 and metastatic cell line COLO357 and FG (198.45±21.22, 221.37±18.59, 182.51±13.48, 317.64±15.20, 331.34±17.18) was significantly higher than that in normal human pancreatic ductal HPDE (98.21±14.54, P<0.05). Transwell cell migration assay and Matrigel cell invasion assay showed that the migration and invasion ability of FG cells after miR-19b silencing [(22.54±2.87)%, (28.87±5.62)%] was significantly decreased as compared with the control group [(99.65±3.07)%, (98.73±4.38)%, P<0.01]. In contrast, the migration and invasion ability of BxPC3 cells overexpressing miR-19b [(317.53±10.21)%, (286.77±12.83)%] was significantly higher than that of the control group [(97.89±5.31)%, (98.25±7.57)%, P<0.01]. The colony formation and MTT assays showed that the proliferation ability of PDAC cells after miR-19b was silenced was significantly decreased as compared with the control group (P<0.01). The result of Western blotting showed that the expression of proliferation markers (p21 and p27) in PDAC was increased by (3.25±0.27) and (5.38±0.33) times respectively as compared with the control group after miR-19b silencing (P<0.01). When miR-19b was overexpressed, the expression of p21 and p27 decreased by (2.68±0.15) and (3.27±0.27) times respectively as compared with the control group (P<0.01). Conclusion MiR-19b could promote the migration and invasion of PDAC cells and increase the proliferation capability. Key words: Pancreatic carcinoma; MicroRNA-19b; Metastsis; Proliferation

Role of microRNA-19b in proliferation and metastasis of pancreatic ductal adenocarcinoma

Objective To examine the expression of miR-19b in pancreatic ductal adenocarcinoma (PDAC) cell lines, and invetigate the functional role of miR-19b in proliferation, migration and invasion of PDAC cells. Methods Real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) was used to detect the expression level of miR-19b in human pancreatic ductal epithelial cell line (HPDE), human PDAC cell lines (PANC1, MiaPaCa2 and BxPC3) and huamn PDAC metastasis cell line COLO357 and its fast-growing variant FG. PDAC cell lines stably over-expressing of low expressing miR-19b were constructed. Transwell assay and Matrigel assay were carried out to examine the migration and invasion capabities of PDAC cells with miR-19b down-regulated or up-regulated. Methyl thiazol tetrazolium (MTT) and colony formation assay were performed on PDAC cell lines with miR-19b silenced or overexpressed. Results The results of RT-qPCR showed the expression level of miR-19b in human PDAC cell lines PANC1, MiaPaCa2, BxPC3 and metastatic cell line COLO357 and FG (198.45±21.22, 221.37±18.59, 182.51±13.48, 317.64±15.20, 331.34±17.18) was significantly higher than that in HPDE (98.21±14.54), (P=0.003, 0.005, 0.021, 0.001, 0.001) and the difference was statistically significant. Transwell cell migration assay and Matrigel cell invasion assay revealed that the migration and invasion ability of FG cells after miR-19b silencing [(22.54±2.87)%, (28.87±5.62)%] was significantly decreased as compared with the control group [(99.65±3.07)%, (98.73±4.38)%], (P=0.005, 0.002) and the difference was statistically significant. In contrast, the migration and invasion ability of BxPC3 cells overexpressing miR-19b [(317.53±10.21)%, (286.77±12.83)%] was significantly higher than that in the control group [(97.89±5.31)%, (98.25±7.57)%] (P=0.003, 0.007) and the difference was statistically significant. The colony formation and MTT assay showed that after miR-19b silencing, the expression of p21 and p27 in PDAC cells was significantly reduced as compared with the control group (P=0.003, 0.005) and the difference was statistically significant. The results of Western blotting indicated that the silencing of miR-19b resulted in the up-regulation of p21 and p27 in PDAC cells by (3.25±0.27, 5.38±0.33) as compared with the control group (P=0.003, 0.001) and the difference was statistically significant. The overexpression of miR-19b led to the down-regulation of p21 and p27 by (2.68±0.15, 3.27±0.27) as compared with the control group (P=0.006, 0.005) and the difference was statistically significant. Conclusion MiR-19b could promote the migration and invasion of PDAC cells and increase the proliferation capability. Key words: MicroRNA-19b; Pancreatic ductal adenocarcinoma; Metastsis; Proliferation

Extracellular matrix components affect cell migration and invasive potential of cultured human pancreatic ductal adenocarcinoma cells

The tumor microenvironment influences cancer cell behavior in relation to tumor progression, as well as cell proliferation and invasion. Pancreatic ductal adenocarcinoma (PDAC) is characterized by an intense desmoplastic reaction and extracellular matrix (ECM) components in the tumor microenvironment are involved in a cross-talk between tumor cells, stromal fibroblasts and ECM components, influencing tumor cell behavior. We aimed at analyzing in vitro the effect of the crosstalk between PDAC cells and the ECM of the microenvironment by culturing PDAC cells on different ECM proteins used as a substrate, in order to better understand the relationship between cancer cell phenotype and the proteins occurring in the desmoplastic tissue. For this purpose, we analyzed some epithelial-to-mesenchymal transition (EMT) markers and the migration and invasive potential in human HPAF-II, HPAC and PL45 PDAC cells cultured on collagen type I (COL), laminin (LAM) and fibronectin (FN). Interestingly, the expression of E-cadherin was not significantly affected, but some differences were revealed by the wound healing assay. In fact, migration of HPAF-II and PL45 cells was decreased on FN and LAM, and increased on COL, compared to control cells grown on plastic (NC). By contrast, HPAC was very rapid and unaffected by the substrate. SDS-zymography showed that COL induced a strong upregulation of MMP-2 activity in HPAF-II and HPAC cells, and of MMP-9 in HPAF-II and PL45 cells, compared to NC. These preliminary results suggest that ECM components could differently affect PDAC migration and invasion, possibly depending on the differentiation grade. The characterization of the mutual effects elicited by the tumor-stroma interplay on the cancer cell will contribute to better understand the influence of the stroma on PDAC cancer cell phenotype, in order to develop new therapeutic strategies.

Pancreatic duct cells as a source of VEGF in mice

Vascular endothelial growth factor (VEGF) is essential for proper pancreatic development, islet vascularisation and insulin secretion. In the adult pancreas, VEGF is thought to be predominantly secreted by beta cells. Although human duct cells have previously been shown to secrete VEGF at angiogenic levels in culture, an analysis of the kinetics of VEGF synthesis and secretion, as well as elucidation of an in vivo role for this ductal VEGF in affecting islet function and physiology, has been lacking. We analysed purified duct cells independently prepared by flow cytometry, surgical isolation or laser-capture microdissection. We infected duct cells in vivo with Vegf (also known as Vegfa) short hairpin RNA (shRNA) in an intrapancreatic ductal infusion system and examined the effect of VEGF knockdown in duct cells in vitro and in vivo. Pancreatic duct cells express high levels of Vegf mRNA. Compared with beta cells, duct cells had a much higher ratio of secreted to intracellular VEGF. As a bioassay, formation of tubular structures by human umbilical vein endothelial cells was essentially undetectable when cultured alone and was substantially increased when co-cultured with pancreatic duct cells but significantly reduced when co-cultured with duct cells pretreated with Vegf shRNA. Compared with islets transplanted alone, improved vascularisation and function was detected in the islets co-transplanted with duct cells but not in islets co-transplanted with duct cells pretreated with Vegf shRNA. Human islet preparations for transplantation typically contain some contaminating duct cells and our findings suggest that the presence of duct cells in the islet preparation may improve transplantation outcomes.

Effect of extracellular matrix components on the expression of epithelial-to-mesenchymal transition markers in cultured human pancreatic ductal adenocarcinoma cells

Epithelial-to-mesenchymal transition (EMT) is a step-wise process leading to the phenotypic switch of epithelial to mesenchymal cells, providing these cells with a metastatic phenotype. During EMT epithelial cells loose adhesion by down regulation of E-cadherin and express N-cadherin, display cytoskeleton reorganization by expressing vimentin and α-smooth muscle actin (αSMA), acquire motile properties and become invasive by secretion of matrix metalloproteinases (MMPs). Cancer cell phenotype is influenced by the tumor microenvironment in relation to tumor progression, as well as to cell proliferation and invasion. The role of the extracellular matrix (ECM) in the microenvironment is particularly relevant in pancreatic ductal adenocarcinoma (PDAC) since this carcinoma is characterized by an intense desmoplastic reaction, representing the environment where the complex interplay between tumor cells, stromal fibroblasts and ECM components occurs. We aimed at analyzing in vitro the effect of the crosstalk between PDAC cells and their microenvironment by characterizing PDAC cell phenotype in cells cultured on different ECM proteins used as a substrate, in order to better understand the relationship between cancer cell behaviour and the proteins occurring in the desmoplastic tissue. We analyzed by immunofluorescence the expression of the main EMT markers such as E-cadherin, N-cadherin, β-catenin, αSMA, vimentin and collagen type I (COL-I) in PDAC cells cultured on laminin, fibronectin, COL-I and without coating (NC). Moreover, we investigated cell proliferation and MMPs activity in cell culture supernatants by SDS-zymography. Cell morphology was similar in PDAC cells cultured on laminin, fibronectin, COL-I, and in NC, as well as the E-cadherin/β-catenin complex, αSMA and COLI expression; by contrast, vimentin was undetectable in all the experimental conditions. N-cadherin was slightly detectable in cells cultured on fibronectin, COL-I, and laminin, and at lower extent in NC cells. Cell proliferation resulted similar in NC and in cells cultured on fibronectin, decreased on laminin and increased on COL-I. MMP-9 activity exhibited a similar trend, resulting similar on fibronectin, decreased on laminin and stimulated on COL-I. These preliminary results provide new insights in the characterization of the mutual effects elicited by the tumor-stroma interplay on the cancer cell, and will contribute to better understand the influence of the stroma on PDAC cancer cell phenotype, in order to develop new therapeutic strategies.

Expansion and conversion of human pancreatic ductal cells into insulin-secreting endocrine cells

Pancreatic islet β-cell insufficiency underlies pathogenesis of diabetes mellitus; thus, functional β-cell replacement from renewable sources is the focus of intensive worldwide effort. However, in vitro production of progeny that secrete insulin in response to physiological cues from primary human cells has proven elusive. Here we describe fractionation, expansion and conversion of primary adult human pancreatic ductal cells into progeny resembling native β-cells. FACS-sorted adult human ductal cells clonally expanded as spheres in culture, while retaining ductal characteristics. Expression of the cardinal islet developmental regulators Neurog3, MafA, Pdx1 and Pax6 converted exocrine duct cells into endocrine progeny with hallmark β-cell properties, including the ability to synthesize, process and store insulin, and secrete it in response to glucose or other depolarizing stimuli. These studies provide evidence that genetic reprogramming of expandable human pancreatic cells with defined factors may serve as a general strategy for islet replacement in diabetes. DOI: http://dx.doi.org/10.7554/eLife.00940.001.

PS2 - 3. The effect of INGAP, FGF7 and a GLP-1R agonist on the differentiation of primary human duct cells towards beta cells

Beta cell replacement by islet transplantation is a promising treatment for patients with type 1 diabetes mellitus. However, shortage of donor tissue demands for an alternative source to generate beta cells. Cells from the pancreatic duct compartment are an attractive alternative source for beta cell replacement therapy.

Cross‐species analysis of nicotine‐induced proteomic alterations in pancreatic cells

Toxic compounds in tobacco, such as nicotine, may adversely affect pancreatic function. We aim to determine nicotine-induced protein alterations in pancreatic cells, thereby revealing links between nicotine exposure and pancreatic disease. We compared the proteomic alterations induced by nicotine treatment in cultured pancreatic cells (mouse, rat, and human stellate cells and human duct cells) using MS-based techniques, specifically SDS-PAGE (gel) coupled with LC-MS/MS and spectral counting. We identified thousands of proteins in pancreatic cells, hundreds of which were identified exclusively or in higher abundance in either nicotine-treated or untreated cells. Interspecies comparisons of stellate cell proteins revealed several differentially abundant proteins (in nicotine treated versus untreated cells) common among the three species. Proteins appearing in all nicotine-treated stellate cells include amyloid beta (A4), procollagen type VI alpha 1, integral membrane protein 2B, and toll-interacting protein. Proteins that were differentially expressed upon nicotine treatment across cell lines were enriched in certain pathways, including nicotinic acetylcholine receptor, cytokine, and integrin signaling. At this analytical depth, we conclude that similar pathways are affected by nicotine, but alterations at the protein level among stellate cells of different species vary. Further interrogation of such pathways will lead to insights into the potential effect of nicotine on pancreatic cells at the biomolecular level and the extension of this concept to the effect of nicotine on pancreatic disease.

Plasticity of Adult Human Pancreatic Duct Cells by Neurogenin3-Mediated Reprogramming

Aims/HypothesisDuct cells isolated from adult human pancreas can be reprogrammed to express islet beta cell genes by adenoviral transduction of the developmental transcription factor neurogenin3 (Ngn3). In this study we aimed to fully characterize the extent of this reprogramming and intended to improve it.MethodsThe extent of the Ngn3-mediated duct-to-endocrine cell reprogramming was measured employing genome wide mRNA profiling. By modulation of the Delta-Notch signaling or addition of pancreatic endocrine transcription factors Myt1, MafA and Pdx1 we intended to improve the reprogramming.ResultsNgn3 stimulates duct cells to express a focused set of genes that are characteristic for islet endocrine cells and/or neural tissues. This neuro-endocrine shift however, is incomplete with less than 10% of full duct-to-endocrine reprogramming achieved. Transduction of exogenous Ngn3 activates endogenous Ngn3 suggesting auto-activation of this gene. Furthermore, pancreatic endocrine reprogramming of human duct cells can be moderately enhanced by inhibition of Delta-Notch signaling as well as by co-expressing the transcription factor Myt1, but not MafA and Pdx1.Conclusions/InterpretationThe results provide further insight into the plasticity of adult human duct cells and suggest measurable routes to enhance Ngn3-mediated in vitro reprogramming protocols for regenerative beta cell therapy in diabetes.

Abstract 1337: Novel model of pancreatic cancer induced by smoking compound NNK

Abstract Background &amp; Aims: Cigarette smoking is a major risk factor for pancreatic cancer. However, the molecular signaling mechanisms through which smoking promotes pancreatic cancer remain unknown. Experimental models of smoking-induced pancreatic cancer have not been developed. Here we studied the effect of cigarette smoking compound: nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on cancer progression in Elastase-Kras (EL-Kras) mice, which have mutated/activated Kras. We further determined the effect of NNK and cigarette smoking extract (CSE) on cell death pathways both in vivo and in vitro in human pancreatic ductal cells. Methods: Wild type and EL-Kras transgenic mice were injected with NNK (100mg/Kg) once a week for 4 weeks. Mice were sacrificed one week later. Analysis of pancreatic lesions, adenocarcinoma, as well as measurement of fibrosis, inflammation, and proliferation were performed by immunohistochemistry. Apoptosis in tissue was assessed by TUNEL assay. Immortalized human ductal cells HPDE6 were cultured for up to 1 week in the presence or absence of NNK (1nM-1µM) or CSE (4ng/ml-4µg/ml). Apoptosis was assessed by measuring DNA fragmentation. Autophagy in cells and in mice pancreatic tissue was assessed by measuring autophagic marker LC3-II with western blot and with immunofluorescence. Results: NNK injections significantly increased (8 times) the number of pancreatic neoplastic lesions in EL-Kras mice. Importantly, NNK induced progression of the pancreatic lesions to the adenocarcinoma stage. Staining of pancreatic tumors with amylase and cytokeratines 7 and 9 showed that cancer cells present the phenotype of both acinar and ductal cells indicating that cells are at the stage of progression to the ductal adenocarcinoma phenotype. Stimulation of pancreatic adenocarcinoma was associated with a decrease in autophagy and apoptosis of exocrine pancreatic cells. NNK inhibited autophagy and apoptosis in pancreas from wild type mice but the effect was much less pronounced. Importantly, NNK injection stimulated fibrosis and stellate cells recruitment and activation. Furthermore, NNK stimulated inflammation. Similarly, exposure to NNK or CSE inhibited apoptosis and autophagy of human ductal cells. NNK and CSE increased Akt phosphorylation both in vivo and in vitro. Pharmacological and molecular inhibition of Akt kinase reversed the smoking inhibitory effect on apoptosis and autophagy, indicating a central role of Akt in the progression of pancreatic cancer by smoking compounds. Further, Akt inhibited autophagy through regulation of AMPK phosphorylation. Conclusion: NNK-induced cancer progression in EL-Kras mice represents the first mouse model of pancreatic cancer induced by smoking and can be utilized to understand the mechanism of progression of the disease. Akt kinase is a key mediator of smoking-induced pancreatic cancer progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1337. doi:1538-7445.AM2012-1337

Abstract 2456: Mechanism of pancreatic cancer induction by smoking

Abstract Background &amp; Aims: Cigarette smoking is a major risk factor for pancreatic cancer. However, the molecular signaling mechanisms of cigarette smoking remain poorly understood. We studied the effects of the cigarette smoking extract (CSE) and the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on apoptosis, proliferation and autophagy and underlying signaling mechanisms both in vitro in human pancreatic ductal cells and in vivo in mouse pancreas. We also studied the effect of K-ras mutation on the smoking-induced cell survival and proliferation. Methods: Immortalized human ductal cells HPDE6 were cultured for up to 1 week in the presence or absence of CSE (0.04-4µg/ml) or NNK (1nM-1µM). Pancreas-specific K-ras transgenic mice EL-K-ras were used as a cancer model. Wild type and EL-K-ras mice were injected with NNK (100mg/Kg) once weekly for 4 weeks and animals sacrificed 72h after the last injection. Apoptosis was assessed by measuring DNA fragmentation with Cell death ELISA or TUNEL and proliferation by 3H-thymidine incorporation into DNA or BrdUrd labeling. Autophagy was measured with its marker LC3 using immunofluorescence staining. Molecular signaling mechanisms were evaluated with Western. Results: Exposure of human ductal cells to CSE and NNK for 24h to 1 week time-dependently decreased apoptosis and autophagy and increased proliferation. Exposure to CSE and NNK decreased AMPK phosphorylation and increased Akt phosphorylation. Akt activation occurred at the times of AMPK inhibition. Pharmacological Akt inactivation reversed the inhibition of AMPK phosphorylation by CSE and NNK and prevented the effects of CSE and NNK on apoptosis and autophagy, indicating a central role of Akt in the prosurvival effects of tobacco compounds. In K-ras mice model of pancreatic cancer NNK injections induced increase in Akt kinase and decrease in AMPK phosphorylation. NNK decreased autophagy and apoptosis and stimulated proliferation in the pancreas. The NNK inhibitory effect on apoptosis and autophagy and the stimulation of proliferation were more pronounced in K-ras mice compared to wild type mice. Conclusion: Our in vitro and in vivo data indicate that smoking compounds create conditions favorable for cancer promotion through activating survival pathways including activation of Akt kinase and inhibition of AMPK activities; this leads to a decrease in apoptosis and autophagy and stimulation of proliferation. Our data suggest that smoking works in concert with K-ras mutation to induce adenocarcinoma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2456.

5′-AZA induces Ngn3 expression and endocrine differentiation in the PANC-1 human ductal cell line

Neurogenin 3 is necessary for endocrine cell development in the embryonic pancreas and has been shown to induce transdifferentiation duct cells from adult pancreas toward a neuro-endocrine phenotype. Here we discovered that the demethylating agent 5′-Azadeoxycytidine (AZA) induced Ngn3 expression and endocrine differentiation from the PANC-1 human ductal cell line. The expression of markers specific to mature islet cells, i.e., glucagon and somatostatin, was also observed. In addition, we demonstrated that growth factors (betacellulin and soluble factors released during pancreas embryogenesis) increased the level of maturation. Our studies revealed that the PANC-1 model system may provide a basis for elucidating the ductal/endocrine differentiation.

Expression of neuropilin-1 in human pancreatic ductal carcinoma and MIA PaCa- II cell lines

Objective To investigate the expression of Neuropilin-1 in human pancreatic ductal adenocarcinoma (PDAC) specimens and cell lines. Methods Expression and distribution of Neuropilin-1 were detected in operation tissue specimens of human pancreatic ductal adenocarcinoma with HE, immunohistochemistry and RT-PCR. Results Immunohistochemical analysis revealed that Neuropilin-1 were expressed in human pancreatic adenocarcinoma specimens, precancerous tissue and MIA PaCa-Ⅱ cell lines, but was absent in normal pancreatic tissue, mRNA of Neuropilin-1 could also be detected the in human pancreatic adenocarcinoma specimens, precancerous tissue and MIA PaCaⅡ cell Lines, while could not be detected in normal pancreatic tissue. Neuropilin-1 expression in pancreatic adenocarcinoma were higher than that in normal pancreas, and the differences were significant( P < 0. 01 ). Conclusions Neuropilin-1 might play an potential role in carcinogenesis for pancreatic cancer. Neuropilin-1 may be relevant to perineural invasion of pancreatic carcinoma by some signal transduction. Key words: Neuropilin-l/Bl; Pancreatic neoplasms/ME

Purinergic receptors stimulate Calcium transport in pancreatic duct cells

Normal pancreatic juice contains &lt;1 mM concentrations of Ca2+, but little is known about Ca2+ homeostasis, which may be an important function of duct epithelium. Our aim was to investigate whether duct cells from human and rat pancreas express Ca2+‐transporting and Ca2+‐binding proteins and whether purinergic receptors regulate Ca2+ transport, as is known for anion transport. Expression analysis revealed that pancreatic ducts of rat and human duct cell line CFPAC‐1 (also PANC‐1 and Capan‐1) express the Na+/Ca2+ exchanger (NCX), as well as the Ca2+‐sensing receptor and the Ca2+‐binding protein calbindin 9kD. These proteins localize to the luminal and lateral membranes of pancreatic duct epithelia. Ca2+ imaging experiments showed that activation of purinergic P2X and P2Y receptors stimulated NCX in rat and human duct cells. Application of ATP to CFPAC‐1 monolayers stimulated Ca2+ transport from the luminal to the basolateral side. Taken together, these results show that pancreatic ducts express a number of Ca2+‐handling proteins and we suggest that these together with purinergic receptors may play a role in regulation of pancreatic Ca2+ transport.Support: PhD scholarship, University of Copenhagen and DNSRC 272‐05‐0420

Investigation and Characterization of the Duct Cell-Enriching Process During Serum-Free Suspension and Monolayer Culture Using the Human Exocrine Pancreas Fraction

We aimed to characterize a serum-free culture system resulting in highly enriched duct cells from human exocrine pancreas. In addition, we tested the effect of vascular endothelial growth factor (VEGF) on endothelial cell proliferation and endocrine differentiation of the duct cells. The exocrine pellet fraction was cultivated in suspension followed by monolayer culture. Time course analysis of multiple acinar and duct cell markers was performed using reverse transcription-polymerase chain reaction and immunocytochemistry. The effects of VEGF and placental growth factor on the quantities of endothelial, duct, and endocrine cells and fibroblasts were investigated using computerized imaging analysis. Suspension culture of the exocrine material efficiently enriched the cultures for duct cells. Frequent acinar cell death as well as cell selective adherence of acinar cells to the culture dish was the underlying cause of the enrichment. Confocal microscopy demonstrated the virtual absence of cells coexpressing duct cell- and acinar cell-specific markers. The endothelial immunoreactivity of the suspension culture system could be increased 2-fold by VEGF treatment, yet no effect was observed on endocrine cell numbers. We have characterized a serum-free in vitro culture system to enrich human duct cells and further show that the contribution of acinoductal transdifferentiation to the enrichment of duct cells is negligible.

Pancreatic Duct Cells in Human Islet Cell Preparations Are a Source of Angiogenic Cytokines Interleukin-8 and Vascular Endothelial Growth Factor

OBJECTIVE—Engraftment and function of human islet cell implants is considered to be dependent on their rapid and adequate revascularization. Studies with rodent islet grafts have shown that vascular endothelial growth factor (VEGF) expression by β-cells can promote this process. The present work examines whether human islet preparations produce VEGF as well as interleukin (IL)-8, another angiogenic protein, and assesses the role of contaminating duct cells in VEGF and IL-8–mediated angiogenesis.RESEARCH DESIGN AND METHODS—Human islet and pancreatic duct cell preparations are compared for their respective expression and production of VEGF and IL-8 during culture as well as following transplantation in nonobese diabetic (NOD)/scid mice. The associated angiogenic effects are measured in an in vitro aortic ring assay and in an in vivo chick embryo chorioallantoic membrane assay.RESULTS—Cultured pancreatic duct cells expressed 3- and 10-fold more VEGF and IL-8, respectively, than cultured human islet endocrine cells and released both proteins at angiogenic levels. The angiogenic effect of purified duct cells was higher than that of purified endocrine islet cells and was completely blocked by a combination of IL-8 and VEGF antibodies. Human duct cell implants under the kidney capsule of NOD/scid mice expressed higher levels of IL-8 and VEGF than human islet cell implants and induced circulating IL-8 and VEGF levels during the first day posttransplantation.CONCLUSIONS—Human duct cell–released IL-8 and VEGF may help revascularization of currently used human islet cell grafts. Further work should examine whether and when this effect can prevail over other inflammatory and immune influences of this cell type.

Adenosine receptors in rat and human pancreatic ducts stimulate chloride transport

Previously, we have shown that pancreatic acini release adenosine triphosphate (ATP) and ATP-handling enzymes, and pancreatic ducts express various purinergic P2 receptors. The aim of the present study was to establish whether pancreatic ducts also express adenosine receptors and whether these could be involved in secretory processes, which involve cystic fibrosis transmembrane regulator (CFTR) Cl- channels or Ca2+-activated Cl- channels and H(+)/HCO(-)(3) transporters. Reverse transcriptase polymerase chain reaction analysis on rat pancreatic ducts and human duct cell adenocarcinoma lines showed that they express A1, A2A, A2B, and A3 receptors. Real-time PCR revealed relatively low messenger RNA levels of adenosine receptors compared to beta-actin; the rank order for the receptors was A2A>A2B>or=A3>>A1 for rat pancreas and A2B>A2A>>A3>or=A1 for duct cell lines. Whole-cell patch-clamp recordings on rat pancreatic ducts showed that, in about half of the recordings, adenosine depolarized the membrane voltage, and this was because of the opening of Cl- channels. Using a Cl--sensitive fluorophore and single-cell imaging on duct cell lines, it was found that 58% of PANC-1 cells responded to adenosine, whereas only 9% of CFPAC-1 cells responded. Adenosine elicited Ca2+ signals only in a few rat and human duct cells, which did not seem to correlate with Cl- signals. A2A receptors were localized in the luminal membranes of rat pancreatic ducts, plasma membrane of many PANC-1 cells, but only a few CFPAC-1 cells. Taken together, our data indicate that A2A receptors open Cl- channels in pancreatic ducts cells with functional CFTR. We propose that adenosine can stimulate pancreatic secretion and, thereby, is an active player in the acini-to-duct signaling.