Steven D Leach

Johns Hopkins Medicine, Baltimore, MD, United States

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Publications (116)757.01 Total impact

  • Elayne Provost, Jerry Rhee, Steven D Leach
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    ABSTRACT: We have adapted a novel multicistronic gene expression system involving viral peptides to the zebrafish. The viral 2A peptide allows production of multiple protein products from a single transgene. Based on highly inefficient peptide bond formation between glycine and proline residues within the 2A peptide, placement of 2A peptide sequence as a linker region between tandem cDNA's allows the stoichiometric translation of multiple unfused protein products. To test this system in zebrafish, we generated two different tandem reporter constructs employing eGFP and mCherry, separated by 2A peptide sequence. Using this system, we produced transgenic zebrafish in which fluorophores were produced as independent proteins from a single transcript. The successful application of this technology in zebrafish will be valuable for visually marking transgenic embryos and transgene-expressing cells, or in any situation where reliable expression of multiple transgenes is desired.
    genesis 11/2007; 45(10):625-9. · 2.58 Impact Factor
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    ABSTRACT: The transgenic enhanced green fluorescent protein (EGFP) expressing 'green' mouse (C57BL/6-TgN(ACTbEGFP)1Osb) is a widely used tool in stem cell research, where the ubiquitous nature of EGFP expression is critical to track the fate of single or small groups of transplanted haematopoietic stem cells (HSC). Our aim was to investigate this assumed ubiquitous expression by performing a detailed histological survey of EGFP expression in these mice. Fluorescent microscopy of frozen tissue sections was used to perform a detailed histological survey of the pattern of EGFP expression in these mice. Flow cytometry was also used to determine the expression pattern in blood and bone marrow. Three patterns of EGFP expression were noted. In most tissues there was an apparently stochastic variegation of the transgene, with individual cell types demonstrating highly variable rates of EGFP expression. Certain specific cell types such as pancreatic ductal epithelium, cerebral cortical neurones and glial cells and glomerular mesangial cells consistently lacked EGFP expression, while others, including pancreatic islet cells, expressed EGFP only at extremely low levels, barely distinguishable from background. Lastly, in the colon and stomach the pattern of EGFP expression was suggestive of clonal inactivation. Only cardiac and skeletal muscle showed near ubiquitous expression. These findings raise questions regarding the 'ubiquitous' expression of EGFP in these transgenic mice and suggest caution in relying overly on EGFP alone as an infallible marker of donor cell origin.
    Pathology 05/2007; 39(2):247-51. · 2.66 Impact Factor
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    ABSTRACT: Determining the functional attributes of pancreatic transcription factors is essential to understand how the pancreas is specified distinct from other endodermal organs, such as liver, stomach and duodenum, and to direct the differentiation of other cell types into pancreas. Previously, we demonstrated that Pdx1-VP16 was sufficient to convert liver to pancreas. In this paper, we characterize the functional ability of another pancreatic transcription factor, Ptf1a, in promoting ectopic pancreatic fates at early stages throughout the endoderm and later during organogenesis. Using the transthyretin promoter to drive expression in the early liver region/bud of transgenic Xenopus tadpoles, we find that Ptf1a-VP16 is able to convert liver to pancreas. Overexpression of the unmodified Ptf1a on the other hand has no effect in liver but is able to convert stomach and duodenum to pancreas. When overexpressed at earlier embryonic stages throughout the endoderm, Ptf1a activity is similarly limited, whereas Ptf1a-VP16 has increased activity. Interestingly, in all instances we find that Ptf1a-VP16 is only capable of promoting acinar cell fates, whereas Ptf1a promotes both acinar and endocrine fates. Lastly, we demonstrate that, similar to mouse and zebrafish, Xenopus Ptf1a is essential for the initial specification of both endocrine and exocrine cells during normal pancreas development.
    Developmental Biology 05/2007; 304(2):786-99. · 3.87 Impact Factor
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    ABSTRACT: Prior studies with transgenic zebrafish confirmed the functionality of the transcription factor Gal4 to drive expression of other genes under the regulation of upstream activator sequences (UAS). However, widespread application of this powerful binary system has been limited, in part, by relatively inefficient techniques for establishing transgenic zebrafish and by the inadequacy of Gal4 to effect high levels of expression from UAS-regulated genes. We have used the Tol2 transposition system to distribute a self-reporting gene/enhancer trap vector efficiently throughout the zebrafish genome. The vector uses the potent, hybrid transcription factor Gal4-VP16 to activate expression from a UAS:eGFP reporter cassette. In a pilot screen, stable transgenic lines were established that express eGFP in reproducible patterns encompassing a wide variety of tissues, including the brain, spinal cord, retina, notochord, cranial skeleton and muscle, and can transactivate other UAS-regulated genes. We demonstrate the utility of this approach to track Gal4-VP16 expressing migratory cells in UAS:Kaede transgenic fish, and to induce tissue-specific cell death using a bacterial nitroreductase gene under UAS control. The Tol2-mediated gene/enhancer trapping system together with UAS transgenic lines provides valuable tools for regulated gene expression and for targeted labeling and ablation of specific cell types and tissues during early zebrafish development.
    Developmental Biology 05/2007; 304(2):811-24. · 3.87 Impact Factor
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    ABSTRACT: In order to generate a zebrafish model of beta cell regeneration, we have expressed an Escherichia coli gene called nfsB in the beta cells of embryonic zebrafish. This bacterial gene encodes a nitroreductase (NTR) enzyme, which can convert prodrugs such as metronidazole (Met) to cytotoxins. By fusing nfsB to mCherry, we can simultaneously render beta cells susceptible to prodrug and visualize Met dependent cell ablation. We show that the neighboring alpha and delta cells are unaffected by prodrug treatment and that ablation is beta cell specific. Following drug removal and 36h of recovery, beta cells regenerate. Using ptf1a morphants, it is clear that this beta cell recovery occurs independently of the presence of the exocrine pancreas. Also, by using photoconvertible Kaede to cell lineage trace and BrdU incorporation to label proliferation, we investigate mechanisms for beta regeneration. Therefore, we have developed a unique resource for the study of beta cell regeneration in a living vertebrate organism, which will provide the opportunity to conduct large-scale screens for pharmacological and genetic modifiers of beta cell regeneration.
    Mechanisms of Development 04/2007; 124(3):218-29. · 2.38 Impact Factor
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    ABSTRACT: It has been suggested that pancreatic acinar cells can serve as progenitors for pancreatic islets, a concept with substantial implications for therapeutic efforts to increase insulin-producing beta cell mass in patients with diabetes. We report what we believe to be the first in vivo lineage tracing approach to determine the plasticity potential of pancreatic acinar cells. We developed an acinar cell-specific inducible Cre recombinase transgenic mouse, which, when mated with a reporter strain and pulsed with tamoxifen, resulted in permanent and specific labeling of acinar cells and their progeny. During various time periods of observation and using several models to provoke injury, we failed to observe any chase of the labeled cells into the endocrine compartment, indicating that acinar cells do not normally transdifferentiate into islet beta cells in vivo in adult mice. In contrast, we observed a substantial role for replication of preexisting acinar cells in the regeneration of new acinar cells after partial pancreatectomy. These results indicate that mature acinar cells harbor a facultative acinar but not endocrine progenitor capacity.
    Journal of Clinical Investigation 04/2007; 117(4):971-7. · 12.81 Impact Factor
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    ABSTRACT: Beta-catenin is an essential mediator of canonical Wnt signaling and a central component of the cadherin-catenin epithelial adhesion complex. Dysregulation of beta-catenin expression has been described in pancreatic neoplasia. Newly published studies have suggested that beta-catenin is critical for normal pancreatic development although these reports reached somewhat different conclusions. In addition, the molecular mechanisms by which loss of beta-catenin affects pancreas development are not well understood. The goals of this study then were; 1] to further investigate the role of beta-catenin in pancreatic development using a conditional knockout approach and 2] to identify possible mechanisms by which loss of beta-catenin disrupts pancreatic development. A Pdx1-cre mouse line was used to delete a floxed beta-catenin allele specifically in the developing pancreas, and embryonic pancreata were studied by immunohistochemistry and microarray analysis. Pdx1-cre floxed beta-catenin animals were viable but demonstrated small body size and shortened median survival. The pancreata from knockout mice were hypoplastic and histologically demonstrated a striking paucity of exocrine pancreas, acinar to duct metaplasia, but generally intact pancreatic islets containing all lineages of endocrine cells. In animals with extensive acinar hypoplasia, putative hepatocyte transdifferention was occasionally observed. Obvious and uniform pancreatic hypoplasia was observed by embryonic day E16.5. Transcriptional profiling of Pdx1-cre floxed beta-catenin embryonic pancreata at E14.5, before there was a morphological phenotype, revealed significant decreases in the beta-catenin target gene N-myc, and the basic HLH transcription factor PTF1, and an increase of several pancreatic zymogens compared to control animals. By E16.5, there was a dramatic loss of exocrine markers and an increase in Hoxb4, which is normally expressed anterior to the pancreas. We conclude that beta-catenin expression is required for development of the exocrine pancreas, but is not required for development of the endocrine compartment. In contrast, beta-catenin/Wnt signaling appears to be critical for proliferation of PTF1+ nascent acinar cells and may also function, in part, to maintain an undifferentiated state in exocrine/acinar cell precursors. Finally, beta-catenin may be required to maintain positional identity of the pancreatic endoderm along the anterior-posterior axis. This data is consistent with the findings of frequent beta-catenin mutations in carcinomas of acinar cell lineage seen in humans.
    BMC Developmental Biology 02/2007; 7:4. · 2.73 Impact Factor
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    ABSTRACT: Abstract Background β-catenin is an essential mediator of canonical Wnt signaling and a central component of the cadherin-catenin epithelial adhesion complex. Dysregulation of β-catenin expression has been described in pancreatic neoplasia. Newly published studies have suggested that β-catenin is critical for normal pancreatic development although these reports reached somewhat different conclusions. In addition, the molecular mechanisms by which loss of β-catenin affects pancreas development are not well understood. The goals of this study then were; 1] to further investigate the role of β-catenin in pancreatic development using a conditional knockout approach and 2] to identify possible mechanisms by which loss of β-catenin disrupts pancreatic development. A Pdx1-cre mouse line was used to delete a floxed β-catenin allele specifically in the developing pancreas, and embryonic pancreata were studied by immunohistochemistry and microarray analysis. Results Pdx1-cre floxed β-catenin animals were viable but demonstrated small body size and shortened median survival. The pancreata from knockout mice were hypoplastic and histologically demonstrated a striking paucity of exocrine pancreas, acinar to duct metaplasia, but generally intact pancreatic islets containing all lineages of endocrine cells. In animals with extensive acinar hypoplasia, putative hepatocyte transdifferention was occasionally observed. Obvious and uniform pancreatic hypoplasia was observed by embryonic day E16.5. Transcriptional profiling of Pdx1-cre floxed β-catenin embryonic pancreata at E14.5, before there was a morphological phenotype, revealed significant decreases in the β-catenin target gene N-myc , and the basic HLH transcription factor PTF1 , and an increase of several pancreatic zymogens compared to control animals. By E16.5, there was a dramatic loss of exocrine markers and an increase in Hoxb4 , which is normally expressed anterior to the pancreas. Conclusion We conclude that β-catenin expression is required for development of the exocrine pancreas, but is not required for development of the endocrine compartment. In contrast, β-catenin/Wnt signaling appears to be critical for proliferation of PTF1+ nascent acinar cells and may also function, in part, to maintain an undifferentiated state in exocrine/acinar cell precursors. Finally, β-catenin may be required to maintain positional identity of the pancreatic endoderm along the anterior-posterior axis. This data is consistent with the findings of frequent β-catenin mutations in carcinomas of acinar cell lineage seen in humans.
    BMC Developmental Biology 01/2007; · 2.73 Impact Factor
  • Pancreas 01/2007; 35(4):405-406. · 2.95 Impact Factor
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    Bidyut Ghosh, Steven D Leach
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    ABSTRACT: In the developing pancreas, the onset of exocrine differentiation is driven by the activity of the PTF1 (pancreas transcription factor 1) transcriptional complex, which is comprised of the class II bHLH (basic helix-loop-helix) protein, Ptf1-p48 [also known as Ptf1a (pancreas specific transcription factor 1a)], and a class I E-box binding partner. Activity of the PTF1 complex is normally inhibited by the Notch signalling pathway, a process mediated by Notch effector proteins in the HES (Hairy/Enhancer of Split) family of bHLH transcriptional repressors. In the present study, we show that this inhibitory effect occurs through direct interaction between HES family members and Ptf1-p48. The HES family members Hey1 (hairy/enhancer-of-split related with YRPW motif 1) and Hey2 co-immunoprecipitate with Ptf1-p48, and Ptf1-p48 binding by Hes1 is also evident in yeast two-hybrid and GST (glutathione S-transferase) pull-down assays. The ability of Hes1 to interact with Ptf1-p48 resides within a fragment comprised of the bHLH, Orange and C-terminal domains, and does not require the N-terminal or WRPW elements. The ability of truncated versions of Hes1 to bind Ptf1-p48 correlates with their ability to down-regulate the activity of the PTF1 transcriptional complex, defining Ptf1-p48 binding as the most likely mechanism by which Notch effector proteins delay exocrine pancreatic differentiation.
    Biochemical Journal 03/2006; 393(Pt 3):679-85. · 4.65 Impact Factor
  • Pancreas 01/2006; 33(4). · 2.95 Impact Factor
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    ABSTRACT: Cellular mechanisms underlying the precision by which neurons target their synaptic partners have largely been determined based on the study of projection neurons. By contrast, little is known about how interneurons establish their local connections in vivo. Here, we investigated how developing amacrine interneurons selectively innervate the appropriate region of the synaptic neuropil in the inner retina, the inner plexiform layer (IPL). Increases (ON) and decreases (OFF) in light intensity are processed by circuits that are structurally confined to separate ON and OFF synaptic sublaminae within the IPL. Using transgenic zebrafish in which the majority of amacrine cells express fluorescent protein, we determined that the earliest amacrine-derived neuritic plexus formed between two cell populations whose somata, at maturity, resided on opposite sides of this plexus. When we followed the behavior of individual amacrine cells over time, we discovered that they exhibited distinct patterns of structural dynamics at different stages of development. During cellular migration, amacrine cells exhibited an exuberant outgrowth of neurites that was undirected. Upon reaching the forming IPL, neurites extending towards the ganglion cell layer were relatively more stable. Importantly, when an arbor first formed, it preferentially ramified in either the inner or outer IPL corresponding to the future ON and OFF sublaminae, and maintained this stratification pattern. The specificity by which ON and OFF amacrine interneurons innervate their respective sublaminae in the IPL contrasts with that observed for projection neurons in the retina and elsewhere in the central nervous system.
    Development 12/2005; 132(22):5069-79. · 6.21 Impact Factor
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    ABSTRACT: Epithelial metaplasia occurs when one predominant cell type in a tissue is replaced by another, and is frequently associated with an increased risk of subsequent neoplasia. In both mouse and human pancreas, acinar-to-ductal metaplasia has been implicated in the generation of cancer precursors. We show that pancreatic epithelial explants undergo spontaneous acinar-to-ductal metaplasia in response to EGFR signaling, and that this change in epithelial character is associated with the appearance of nestin-positive transitional cells. Lineage tracing involving Cre/lox-mediated genetic cell labeling reveals that acinar-to-ductal metaplasia represents a true transdifferentiation event, mediated by initial dedifferentiation of mature exocrine cells to generate a population of nestin-positive precursors, similar to those observed during early pancreatic development. These results demonstrate that a latent precursor potential resides within mature exocrine cells, and that this potential is regulated by EGF receptor signaling. In addition, these observations provide a novel example of rigorously documented transdifferentiation within mature mammalian epithelium, and suggest that plasticity of mature cell types may play a role in the generation of neoplastic precursors.
    Development 09/2005; 132(16):3767-76. · 6.21 Impact Factor
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    ABSTRACT: The non-neoplastic pancreatic parenchyma adjacent to infiltrating ductal adenocarcinoma demonstrates inflammation, fibrosis, acinar cell loss and small duct-like metaplasia of acinar cells. Similar morphologic changes are also observed in the setting of chronic pancreatitis. In addition, peritumoral acini have been shown to have alterations in gene expression even in the absence of morphological changes. To better understand the pancreatic acinar responses to infiltrating pancreatic ductal adenocarcinoma, we characterized gene expression patterns of pancreatic acinar tissue adjacent to infiltrating pancreatic ductal adenocarcinomas and compared them to gene expression patterns of acinar tissue affected by chronic pancreatitis as well as to those of normal pancreatic acini. Fresh-frozen pancreatic acinar tissue was microdissected from nine patients (three with pancreatic cancer, three with chronic pancreatitis, three with normal pancreata) using laser capture microdissection, and extracted RNA from each microdissection was subjected to two rounds of linear amplification and hybridized to oligonucleotide microarrays. Gene expression patterns were confirmed using quantitative RT-PCR and/or immunohistochemistry. A total of 20 genes was found to be overexpressed in peritumoral acinar tissue compared to normal acinar tissue and to acini affected by chronic pancreatitis. These 20 genes included pancreatitis-associated protein (HIP/PAP), a gene known to be overexpressed in acini adjacent to infiltrating pancreatic cancer, and the gene cartilage glycoprotein-39 (HC gp-39 or TKL-40). Serum HC gp-39 protein levels were significantly higher in patients with pancreatic cancer and in those with chronic pancreatitis than in controls without pancreatic disease. There was no significant difference in the levels of serum HC gp-39 in patients with pancreatic cancer and those with chronic pancreatitis. Our results demonstrate some of the molecular alterations in acinar cells that occur in response to adjacent infiltrating pancreatic ductal adenocarcinoma and reveal that such alterations can provide a rich source of markers of pancreatic cancer.
    Modern Pathology 07/2005; 18(6):779-87. · 5.25 Impact Factor
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    ABSTRACT: Increase of intramucosal transforming growth factor alpha (TGFalpha) levels in the gastric fundus leads to oxyntic atrophy and massive foveolar hyperplasia in both metallothionein (MT)-TGFalpha mice and patients with Ménétrier's disease. We have evaluated the hypothesis that increased levels of TGFalpha in the fundus induces an antral pattern of cell differentiation in fundic glands by studying Pdx1, a transcription factor whose expression normally is confined to the gastric antrum. Induction of Pdx1 expression was evaluated in Pdx1(lacZ/+)/MT-TGFalpha bigenic mice treated with zinc. The distribution of Pdx1 in MT-TGFalpha mice and Ménétrier's disease patients was evaluated with anti-Pdx1 antibodies. Transcript levels were evaluated by quantitative polymerase chain reaction in mouse and human tissues and AGS cells. In Pdx1(lacZ/+) mice, Pdx1 was expressed in antral mucosal cells including gastrin cells and TFF2-expressing deep glandular mucous cells. Zinc treatment for 2 to 8 weeks in Pdx1(lacZ/+)/MT-TGFalpha transgenic mice resulted in expression of Pdx1 throughout the fundus. No ectopic fundic Pdx1 expression was observed in either H. felis-infected or DMP777-treated mice. In MT-TGFalpha mice, 8 weeks of zinc treatment elicited nuclear Pdx1 staining throughout the fundic mucosa. TGFalpha treatment in AGS cells led to increases in Pdx1 and gastrin messenger RNA expression. Fundic sections from Ménétrier's disease patients showed nuclear Pdx1 staining throughout the fundic glands. Treatment of a Ménétrier's disease patient with an anti-epidermal growth factor receptor monoclonal antibody reduced fundic expression of both Pdx1 and gastrin. Overexpression of TGFalpha in MT-TGFalpha mice and Ménétrier's disease patients elicits ectopic expression in the fundus of Pdx1, consistent with the phenotype of antralization.
    Gastroenterology 05/2005; 128(5):1292-305. · 12.82 Impact Factor
  • Steven D Leach
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    ABSTRACT: Changes in epithelial differentiation represent a characteristic early feature of human pancreatic cancer. Recent work suggests that many of these changes may reflect a pathologic recapitulation of developmental events. Reflecting this principle, metaplastic and neoplastic pancreatic epithelium appear to share many features in common with embryonic pancreatic epithelium, including reactivation of the Notch signaling pathway. In this review, we summarize recent studies involving regulation of epithelial differentiation in both embryonic and adult pancreas and highlight the role of Notch in regulating an exocrine progenitor pool.
    Journal of Clinical Gastroenterology 05/2005; 39(4 Suppl 2):S78-82. · 3.20 Impact Factor
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    ABSTRACT: Adenocarcinomas of the ampulla of Vater demonstrate a characteristic histology but vary significantly in outcome. As a consequence, prognostic factors for these cancers are poorly defined. The caudal-type homeodomain transcription factors 1 (CDX1) and 2 (CDX2) regulate axial development and intestinal differentiation. We assessed the expression of these putative intestinal epithelial-specific transcription factors and their influence on patient outcome. Fifty-three resected carcinomas of the ampulla of Vater, 31 pancreatic ductal adenocarcinomas, and 15 extrahepatic biliary carcinomas were analyzed for CDX1 and CDX2 expression using immunohistochemistry. Forty percent of carcinomas of the ampulla of Vater but less than 5% of pancreatic and biliary adenocarcinomas expressed CDX. Expression of CDX was associated with a better prognosis (P = .0009). Individually, both CDX1 (P = .02) and CDX2 (P = .02) expression were associated with a survival advantage on univariate analysis. Advanced T stage (P = .02), lymph node metastases (P = .004), and vascular space invasion (P = .0009) were associated with a poor prognosis. Multivariate analysis revealed vascular space invasion (P = .01) and CDX expression (P = .01) to be independent prognostic factors. Expression of CDX was an independent marker of outcome in patients with resected adenocarcinoma of the ampulla of Vater. Expression of CDX may distinguish good prognosis intestinal-like tumors, which potentially arise within intestinal epithelium, from poorer prognosis pancreatobiliary tumors, which arise in adjacent pancreatic and/or biliary ductal epithelium.
    Journal of Clinical Oncology 04/2005; 23(9):1811-8. · 18.04 Impact Factor
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    ABSTRACT: Invasive pancreatic cancer is thought to develop through a series of noninvasive duct lesions known as pancreatic intraepithelial neoplasia (PanIN). We used cDNA microarrays interrogating 15,000 transcripts to identify 49 genes that were differentially expressed in microdissected early PanIN lesions (PanIN-1B/2) compared with microdissected normal duct epithelium. In this analysis, a cluster of extrapancreatic foregut markers, including pepsinogen C, MUC6, KLF4, and TFF1, was found to be up-regulated in PanIN. Up-regulation of these genes was further validated using combinations of real-time reverse transcription-PCR, in situ hybridization, and immunohistochemistry in a total of 150 early PanIN lesions from 81 patients. Identification of these gastrointestinal transcripts in human PanIN prompted assessment of other foregut markers by both semiquantitative and real-time reverse transcription-PCR, revealing similar up-regulation of Sox-2, Gastrin, HoxA5, GATA4/5/6, Villin and Forkhead 6 (Foxl1). In contrast to frequent expression of multiple gastric epithelial markers, the intestinal markers intestinal fatty acid binding protein, CDX1 and CDX2 were rarely expressed either in PanIN lesions or in invasive pancreatic cancer. Hedgehog pathway activation induced by transfection of immortalized human pancreatic ductal epithelial cells with Gli1 resulted in up-regulation of the majority of foregut markers seen in early PanIN lesions. These data show frequent up-regulation of foregut markers in early PanIN lesions and suggest that PanIN development may involve Hedgehog-mediated conversion to a gastric epithelial differentiation program.
    Cancer Research 04/2005; 65(5):1619-26. · 8.65 Impact Factor
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    ABSTRACT: The developmental plasticity of adult pancreas is evidenced by the ability to undergo conversion between different epithelial cell types. Specific examples of such conversions include acinar to ductal metaplasia, ductal to islet metaplasia, and generation of ductal structures within islets. Although 90% of human pancreatic cancers are classified as ductal adenocarcinoma, markers of all pancreatic epithelial cell types (acini, ductal, and endocrine) as well as markers of gastric and intestinal lineages can be detected in these tumors. In recent years considerable knowledge has been gained regarding regulation of cellular differentiation and various signaling pathways involved in normal and neoplastic pancreas through studies of pancreatic cancer and immortalized ductal cell lines. However, these studies provide little insight into the context of normal developmental cues, the disruption of which leads to organ pathology. Here we have described a detailed method for preparation, maintenance, and manipulation of adult and embryonic mouse pancreas. These methods may be utilized in studies involving normal epithelial differentiation, contributing to improved understanding of pancreatic development and disease.
    Methods in molecular medicine 02/2005; 103:259-71.
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    ABSTRACT: Background & Aims: Increase of intramucosal transforming growth factor α (TGFα) levels in the gastric fundus leads to oxyntic atrophy and massive foveolar hyperplasia in both metallothionein (MT)-TGFα mice and patients with Ménétrier’s disease. We have evaluated the hypothesis that increased levels of TGFα in the fundus induces an antral pattern of cell differentiation in fundic glands by studying Pdx1, a transcription factor whose expression normally is confined to the gastric antrum. Methods: Induction of Pdx1 expression was evaluated in Pdx1lacZ/+/MT-TGFα bigenic mice treated with zinc. The distribution of Pdx1 in MT-TGFα mice and Ménétrier’s disease patients was evaluated with anti-Pdx1 antibodies. Transcript levels were evaluated by quantitative polymerase chain reaction in mouse and human tissues and AGS cells. Results: In Pdx1lacZ/+ mice, Pdx1 was expressed in antral mucosal cells including gastrin cells and TFF2-expressing deep glandular mucous cells. Zinc treatment for 2 to 8 weeks in Pdx1lacZ/+/MT-TGFα transgenic mice resulted in expression of Pdx1 throughout the fundus. No ectopic fundic Pdx1 expression was observed in either H felis-infected or DMP777-treated mice. In MT-TGFα mice, 8 weeks of zinc treatment elicited nuclear Pdx1 staining throughout the fundic mucosa. TGFα treatment in AGS cells led to increases in Pdx1 and gastrin messenger RNA expression. Fundic sections from Ménétrier’s disease patients showed nuclear Pdx1 staining throughout the fundic glands. Treatment of a Ménétrier’s disease patient with an anti-epidermal growth factor receptor monoclonal antibody reduced fundic expression of both Pdx1 and gastrin. Conclusions: Overexpression of TGFα in MT-TGFα mice and Ménétrier’s disease patients elicits ectopic expression in the fundus of Pdx1, consistent with the phenotype of antralization.
    Gastroenterology 01/2005; 128(5):1292-1305. · 12.82 Impact Factor

Publication Stats

5k Citations
488 Downloads
757.01 Total Impact Points

Institutions

  • 2003–2013
    • Johns Hopkins Medicine
      • • McKusick-Nathans Institute of Genetic Medicine
      • • Department of Surgery
      • • Department of Cell Biology
      Baltimore, MD, United States
  • 2003–2011
    • Johns Hopkins University
      • Department of Surgery
      Baltimore, MD, United States
  • 2009
    • University of Pennsylvania
      • Division of Gastroenterology
      Philadelphia, PA, United States
  • 2008
    • Carnegie Institution for Science
      • Department of Embryology
      Washington, WV, United States
  • 1998–2005
    • Vanderbilt University
      • • Department of Surgery
      • • Department of Cancer Biology
      • • Department of Radiology and Radiological Sciences
      • • Division of Surgical Oncology
      Nashville, MI, United States
  • 2001
    • Gateway-Vanderbilt Cancer Treatment Center
      Clarksville, Tennessee, United States
  • 1999
    • University of Cincinnati
      • Department of Surgery
      Cincinnati, Ohio, United States
  • 1995–1998
    • University of Texas MD Anderson Cancer Center
      • Department of Surgical Oncology
      Houston, TX, United States