Identification, culture, and characterization of pancreatic stellate cells in rats and humans

BACKGROUND & AIMS

Until now, the basic matrix-producing cell type responsible for pancreas fibrosis has not been identified. In this report, retinoid-containing pancreatic stellate cells (PSCs) in rat and human pancreas are described, and morphological and biochemical similarities to hepatic stellate cells are shown.

METHODS

Electron and immunofluorescence microscopy (collagen types I and III, fibronectin, laminin, alpha-actin, and desmin) was performed using pancreatic tissue and cultured PSCs. Extracellular matrix synthesis was shown using quantitative immunoassay and Northern blot analysis.

RESULTS

PSCs are located in interlobular areas and in interacinar regions. Early primary cultured PSCs contain retinol and fatty acid retinyl-esters. Addition of retinol to passaged cells resulted in retinol uptake and esterification. During primary culture, the cells changed from a quiescent fat-storing phenotype to a highly synthetic myofibroblast-like cell expressing iso-alpha-smooth muscle actin (>90%) and desmin (20%-40%) and showing strong positive staining with antibodies to collagen types I and III, fibronectin, and laminin. As determined on protein and messenger RNA level, serum growth factors stimulated the synthesis of collagen type I and fibronectin.

CONCLUSIONS

The identification of PSCs, particularly in fibrotic areas, and the similarities of these cells to hepatic stellate cells suggest that PSCs participate in the development of pancreas fibrosis.

Sulfasalazine: a potent and specific inhibitor of nuclear factor kappa B

Transcription factors of the NF-kappaB/Rel family are critical for inducible expression of multiple genes involved in inflammatory responses. Sulfasalazine and its salicylate moiety 5-aminosalicylic acid are among the most effective agents for treating inflammatory bowel disease and rheumatoid arthritis. However, the mode of action of these drugs remains unclear. Here we provide evidence that the transcription factor NF-kappaB is a target of sulfasalazine-mediated immunosuppression. Treatment of SW620 colon cells with sulfasalazine inhibited TNFalpha-, LPS-, or phorbol ester- induced NF-kappaB activation. NF-kappaB-dependent transcription was inhibited by sulfasalazine at micro- to millimolar concentrations. In contrast, 5-aminosalicylic acid or sulfapyridine did not block NF-kappaB activation at all doses tested. TNFalpha-induced nuclear translocation of NF-kappaB was prevented by sulfasalazine through inhibition of IkappaBalpha degradation. When blocking proteasome-mediated degradation of IkappaBalpha, we could demonstrate that sulfasalazine interfered with IkappaBalpha phosphorylation, suggesting a direct effect on an IkappaBalpha kinase or on an upstream signal. Inhibition of NF-kappaB activation seems to be specific since other DNA-binding activities such as AP1 were not affected. These results demonstrate that sulfasalazine is a potent and specific inhibitor of NF-kappaB activation, and thus may explain some of the known biological properties of sulfasalazine.

p300 acts as a transcriptional coactivator for mammalian Notch-1

Notch-1 belongs to a family of transmembrane receptor proteins that direct the decisions as to various cell fates. After ligand binding, a proteolytic cleavage step occurs and the intracellular part of Notch-1, Notch-1-IC, translocates into the nucleus, where it targets the DNA binding protein RBP-J kappa/CBF1. RBP-J kappa mediates repression through recruitment of a histone deacetylase-containing complex. The Notch-1-IC/RBP-J kappa complex overcomes repression and activates the transcription of Notch target genes. We have identified a novel domain in Notch-1-IC, the EP domain, which is indispensable for full transcriptional activation. This transactivation domain is localized adjacent to the ankyrin repeats of Notch-1-IC. In cotransfection experiments, Notch-1-IC-mediated transcriptional activation was inhibited by E1A12S and p53, two proteins, which interfere with the function of the common coactivator p300. Protein-protein interaction assays demonstrated the association of Notch-1-IC and the CH3 region of p300. In addition, the interaction of mammalian Notch-1-IC with p300 was destabilized after deletion of the EP domain of Notch-1-IC. Based on physical interaction with Notch-1-IC and coactivator functions of p300, we propose a model for Notch-1-mediated gene regulation via p300.

Suppression of NF-kappaB activity by sulfasalazine is mediated by direct inhibition of IkappaB kinases alpha and beta

BACKGROUND & AIMS

Activation of NF-kappaB/Rel has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Various drugs used in the treatment of IBD, such as glucocorticoids, 5-aminosalicylic acid, and sulfasalazine, interfere with NF-kappaB/Rel signaling. The aim of this study was to define the molecular mechanism by which sulfasalazine inhibits NF-kappaB activation.

METHODS

The effects of sulfasalazine and its moieties on NF-kappaB signaling were evaluated using electromobility shift, transfection, and immune complex kinase assays. The direct effect of sulfasalazine on IkappaB kinase (IKK) activity was investigated using purified recombinant IKK-alpha and -beta proteins.

RESULTS

NF-kappaB/Rel activity induced by tumor necrosis factor alpha, 12-O-tetradecanoylphorbol-13-acetate, or overexpression of NF-kappaB-inducing kinase, IKK-alpha, IKK-beta, or constitutively active IKK-alpha and IKK-beta mutants was inhibited dose dependently by sulfasalazine. Sulfasalazine inhibited tumor necrosis factor alpha-induced activation of endogenous IKK in Jurkat T cells and SW620 colon cells, as well as the catalytic activity of purified IKK-alpha and IKK-beta in vitro. In contrast, the moieties of sulfasalazine, 5-aminosalicylic acid, and sulfapyridine or 4-aminosalicylic acid had no effect. Activation of extracellular signal-related kinase (ERK) 1 and 2, c-Jun-N-terminal kinase (JNK) 1, and p38 was unaffected by sulfasalazine. The decrease in substrate phosphorylation by IKK-alpha and -beta is associated with a decrease in autophosphorylation of IKKs and can be antagonized by excess adenosine triphosphate.

CONCLUSIONS

These data identify sulfasalazine as a direct inhibitor of IKK-alpha and -beta by antagonizing adenosine triphosphate binding. The suppression of NF-kappaB activation by inhibition of the IKKs contributes to the well-known anti-inflammatory and immunosuppressive effects of sulfasalazine.

Claudin-4: a new target for pancreatic cancer treatment using Clostridium perfringens enterotoxin

BACKGROUND & AIMS

Recently, several members of the claudin family have been identified as integral constituents of tight junctions. Using expression profiling, we previously found claudin-4 to be overexpressed in pancreatic cancer. Because claudin-4 has been described as a receptor for the cytotoxic Clostridium perfringens enterotoxin (CPE), we investigated the effect of CPE on pancreatic cancer cells.

METHODS

Expression of claudin-4 was analyzed by Northern blots. In vitro toxicity of CPE was determined by trypan blue exclusion and the (86)Rb-release assay. The in vivo effect of CPE was studied in claudin-4-expressing nude mouse xenografts of the Panc-1 cell line.

RESULTS

Expression analyses showed that claudin-4 was overexpressed in most pancreatic cancer tissues and cell lines and several other gastrointestinal tumors. CPE led to an acute dose-dependent cytotoxic effect, restricted to claudin-4-expressing cells and dependent on claudin-4 expression levels. Furthermore, transforming growth factor beta was identified as a negative modulator of both claudin-4 expression and susceptibility to CPE. In vivo, intratumoral injections of CPE in Panc-1 xenografts led to large areas of tumor cell necrosis and significant reduction of tumor growth.

CONCLUSIONS

Our findings suggest that targeting claudin-4-expressing tumors with CPE represents a promising new treatment modality for pancreatic cancer and other solid tumors.

Cloning of a gene highly overexpressed in cancer coding for a novel KH-domain containing protein

In a previous large scale screen for differentially expressed genes in pancreatic cancer, we identified a gene highly overexpressed in cancer encoding a novel protein with four K-homologous (KH) domains. KH-domains are found in a subset of RNA-binding proteins, including pre-mRNA-binding (hnRNP) K protein and the fragile X mental retardation gene product (FMR1). By fluorescence in situ hybridization (FISH) the identified gene named koc (KH domain containing protein overexpressed in cancer) was assigned to chromosome 7p11.5. Two pseudogenes were localised on chromosome 6 and 11. The cloned koc cDNA has a 250 bp 5'-UTR, a 1740 bp ORF and a 2168 bp 3'-UTR. The AU-rich 3'-untranslated region of koc contains eight AUUUA and four AUUUUUA reiterated motifs. The deduced koc protein with 580 amino-acids has a relative molecular mass (Mr) of approximately 65,000 (65 K). The koc transcript is highly overexpressed in pancreatic cancer cell lines and in pancreatic cancer tissue as compared to both, normal pancreas and chronic pancreatitis tissue. High levels of expression were as well found in tissue samples of other human tumours. As the KH domain has been shown to be involved in the regulation of RNA synthesis and metabolism, we speculate that koc may assume a role in the regulation of tumour cell proliferation by interfering with transcriptional and or posttranscriptional processes. However, the precise role of koc in human tumour cells is unknown and remains to be elucidated.

NF-kappaB2 is a putative target gene of activated Notch-1 via RBP-Jkappa

NF-kappaB2 (p100/p52), a member of the NF-kappaB/Rel family of transcription factors, is involved in the regulation of a variety of genes important for immune function. Previously, we have shown that the NF-kappaB2 gene is regulated in a positive and a negative manner. Two kappaB elements within the NF-kappaB2 promoter mediate tumor necrosis factor alpha-inducible transactivation. In addition, we have shown that there exists a transcriptional repression in the absence of NF-kappaB. To identify a DNA binding activity responsible for this transcriptional repression, we have partially purified a nuclear complex, named Rep-kappaB. Here we further analyze this putative repressive binding activity. Detailed examination of Rep-kappaB-DNA interaction revealed the sequence requirements for binding to be almost identical to those of recombination signal binding protein Jkappa (RBP-Jkappa), the mammalian homolog of the protein encoded by Drosophila suppressor of hairless [Su(H)]. In addition, in electromobility shift assays, Rep-kappaB binding activity is recognized by an antibody directed against RBP-Jkappa. By performing transient-transfection assays, we show that human RBP-Jkappa represses basal as well as RelA (p65)-stimulated NF-kappaB2 promoter activity. Studies in Drosophila melanogaster have shown that Su(H) is implicated in the Notch signaling pathway regulating cell fate decisions. In transient-transfection assays we show that truncated Notch-1 strongly induces NF-kappaB2 promoter activity. In summary, our data clearly demonstrate that Rep-kappaB is closely related or identical to RBP-Jkappa. RBP-Jkappa is a strong transcriptional repressor of NF-kappaB2. Moreover, this repression can be overcome by activated Notch-1, suggesting that NF-kappaB2 is a novel putative Notch target gene.

NF-kappaB/Rel activation in cerulein pancreatitis

BACKGROUND & AIMS

Recent evidence suggests that a number of rapid signaling cascades are initiated during secretagogue-induced pancreatitis. However, little is known about the nuclear events. The aim of this study was to explore activation of the transcription factor NF-kappaB/Rel after supramaximal stimulation with the cholecystokinin analogue cerulein in the pancreas.

METHODS & RESULTS

Nuclear appearance of NF-kappaB/Rel-binding activity was detectable 15 minutes after cerulein injection. The DNA-binding activity consisted of NF-kappaB1 p50, NF-kappaB2 p52, and RelA p65 as judged by supershift assays and Western blot analysis. The onset and termination of NF-kappaB/Rel activation correlated with the degradation and reappearance of IkappaBalpha. Cerulein in supramaximal but not in physiological doses activated NF-kappaB/Rel in vitro. After blocking of NF-kappaB/Rel activation with pyrrolidine dithiocarbamate, the degree of morphological alterations was more pronounced than in controls, serum amylase and lactate dehydrogenase levels were significantly increased, and messenger RNA levels of pancreatitis-associated protein were more strongly induced, reflecting a more severe degree of pancreatitis. Similar results were obtained when N-acetyl-L-cysteine was used as an inhibitor of NF-kappaB activation.

CONCLUSIONS

These data show that NF-kappaB/Rel is rapidly activated during cerulein pancreatitis. This activation may induce a self-defending genetic program before the onset of cellular injury, which might prevent higher degrees of damage of pancreatic acinar cells after secretagogue hyperstimulation.

Metabolic and weight-loss effects of a long-term dietary intervention in obese patients

BACKGROUND

Obesity is a chronic disease that has become one of the most serious health problems in Western society.

OBJECTIVE

We assessed the long-term effects of an energy-restricted diet combined with 1 or 2 daily meal replacements on body weight and biomarkers of disease risk in 100 obese patients.

DESIGN

Phase 1 consisted of a 3-mo, prospective, randomized, parallel intervention study of 2 dietary interventions to reduce weight. The energy-restricted diet (5.2-6.3 MJ/d) consisted of conventional foods (group A) or an isoenergetic diet with 2 meals and 2 snacks replaced daily by energy-controlled, vitamin-and-mineral-supplemented prepared foods (group B). Phase 2 consisted of a 24-mo, case-control, weight-maintenance study with an energy-restricted diet and 1 meal and 1 snack replaced daily for all patients.

RESULTS

Total weight loss (as a percentage of initial body weight) was 5.9+/-5.0% in group A and 11.3+/-6.8% in group B (P < 0.0001). During phase 1, mean weight loss in group B (n = 50) was 7.1+/-3.5 kg, with significant reductions in plasma triacylglycerol, glucose, and insulin concentrations (P < 0.0001). Group A patients (n = 50) lost an average of 1.3+/-2.2 kg with no significant improvements in these biomarkers. During phase 2, both groups lost on average an additional 0.07% of their initial body weight every month (P < 0.01). During the 27-mo study, both groups experienced significant reductions in systolic blood pressure and plasma concentrations of triacylglycerol, glucose, and insulin (P < 0.01).

CONCLUSION

These findings support the hypothesis that defined meal replacements can be used for successful, long-term weight control and improvements in certain biomarkers of disease risk.

Overexpression and activation of the tyrosine kinase Src in human pancreatic carcinoma

Src family tyrosine kinases participate in the regulation of cell adhesion, cell growth and differentiation. Here, we examine for the first time the potential role of Src for growth regulation of human pancreatic carcinoma cells. By immunohistochemical analysis, Src was overexpressed in 13/13 pancreatic carcinoma tissue but not in 6 normal pancreatic tissue specimen. In Western blots of total cellular extracts, Src protein expression was elevated in 14/17 carcinoma cell lines as compared to normal pancreas or cultured human pancreatic duct cells. Kinase activity was only detectable in cancer cells and did not correlate with the amount of kinase protein or with the expression of the regulatory kinase Csk, indicating that Src is not regulated through protein expression or through expression of Csk. The Src-specific tyrosine kinase inhibitor herbimycin A decreased cell growth in a dose-dependent manner. We suggest that Src family kinases participate in growth regulation of pancreatic cancer cells.

Expression and in-situ localization of genes coding for extracellular matrix proteins and extracellular matrix degrading proteases in pancreatic cancer

Pancreatic cancer shows a strong desmoplastic reaction characterized by a remarkable proliferation of interstitial connective tissue (collagens type I and III, fibronectin). In this study we have analyzed the balance of expression of mRNAs encoding extracellular matrix components (collagens I, III and IV, laminin, fibronectin), extracellular matrix-degrading metalloproteinases (MMP-1, -2, -3 and -9) and tissue inhibitors of metalloproteinases (TIMP-1 and -2) in pancreatic cancer and control pancreatic tissue by Northern-blot analysis and mRNA in situ hybridization. Transcripts for MMP-1 (interstitial collagenase) and MMP-3 (stromelysin-1) were not detectable in pancreatic cancer and control tissues. Steady-state levels of transcripts encoding extracellular matrix proteins, MMP-2 (72-kDa collagenase IV), MMP-9 (92-kDa collagenase type IV), TIMP-1 and TIMP-2 were elevated in the majority of pancreatic-cancer tissue samples as compared to control pancreatic tissue. A good correlation was seen between overexpression of these MMPs and TIMPs and the steady-state levels of transcripts coding for extracellular matrix proteins, the amount of collagen protein and the severity of the desmoplastic reaction. In situ hybridization studies localized transcripts coding for collagens type I and III to spindle-shaped stromal cells, whereas transcripts for MMP-2, MMP-9, TIMP-1 and TIMP-2 were found in both stromal and tumor cells. However, MMP-2 transcripts appeared to be more abundant in stromal cells, TIMP-1 and TIMP-2 transcripts were evenly distributed over tumor and stromal cells and relatively more MMP-9 transcripts were found in tumor cells. We conclude that, in human pancreatic cancer, MMP-2, MMP-9, TIMP-1 and TIMP-2 may be involved in processes leading to the strong desmoplastic reaction observed in these tumors. Both stromal and tumor cells appear to be the source of MMPs and TIMPs in human pancreatic cancer.

EEG coherence in Alzheimer's dementia

In Alzheimer's dementia (AD) axonal disruption and cholinergic deficit lead to impaired cortical connectivity and to a decrease in EEG alpha coherence. The aim of the present study was to assess the usefulness of coherence parameters of the EEG for the diagnostics of AD. Quantitative EEG analyses were performed in 31 AD patients and 17 cognitively unimpaired depressive controls, both groups without psychopharmacological treatment. Differences between groups were examined and the diagnostic significance of EEG parameters was assessed by means of stepwise logistic regression analyses. In the AD patients global theta power was increased, left temporal alpha coherence and interhemispheric theta coherence were decreased. Left temporal alpha coherence and global theta power allowed an identification of AD patients with a sensitivity of 87% and a specificity of 77%. Quantitative analyses, especially the determination of left temporal alpha coherence, may enhance the usefulness of the EEG in the diagnostics of AD.

Proinflammatory cytokines increase glial fibrillary acidic protein expression in enteric glia

BACKGROUND

Enteric glia protect the integrity of the gut, as loss of enteric glial fibrillary acidic protein (GFAP) positive (+) glia leads to a haemorrhagic jejunoileitis. Crohn's disease (CD) and necrotising enterocolitis (NEC) show pathological changes in enteric glia. Therefore, factors controlling GFAP+ enteric glia are of great interest. The aim of the present study was to characterise enteric glia and determine the effect of interleukin 1beta (IL-1beta), interleukin 4 (IL-4), tumour necrosis factor alpha (TNF-alpha), and lipopolysaccharides (LPS) on cultured enteric glia.

METHODS

Dissected rat colon and cultured enteric glia cells were double labelled with anti-GFAP and anti-S-100 antibodies. For regulatory studies, enteric glia cells were treated with cytokines and LPS. Proliferation was assayed using bromodeoxyuridine (BrdU) and mitosis of enteric glia was blocked by demecolcine.

RESULTS

We were able to distinguish GFAP negative (-) from GFAP+ glia subtypes in situ and in primary cultures. Incubation of cells with IL-1beta, TNF-alpha, and LPS led to a significant increase in GFAP+ enteric glia while IL-4 had no effect on GFAP expression. After incubation with IL-1beta, total intracellular GFAP of enteric glia cells was increased. Upregulation of GFAP+ enteric glia could also be observed after stimulation with IL-1beta on blocking mitosis. BrdU uptake in stimulated enteric glia showed no increased proliferation rate.

CONCLUSIONS

Two different types of enteric glia based on GFAP expression exist in the gut. Proinflammatory cytokines and LPS cause a dramatic increase in GFAP+ enteric glia. This suggests that cytokines play an important role in controlling GFAP+ enteric glia which might in turn be involved in modulating the integrity of the bowel during inflammation.

Identification of mediators stimulating proliferation and matrix synthesis of rat pancreatic stellate cells

The aim of this study was to identify fibrogenic mediators stimulating activation, proliferation, and/or matrix synthesis of rat pancreatic stellate cells (PSC). PSC were isolated from the pancreas of normal Wistar rats and from rats with cerulein pancreatitis. Cell activation was demonstrated by immunofluorescence microscopy of smooth muscle alpha-actin (SMA) and real-time quantitative RT-PCR of SMA, fibronectin, and transforming growth factor (TGF)-beta(1). Proliferation was measured by bromodeoxyuridine incorporation. Matrix synthesis was demonstrated on the protein and mRNA level. Within a few days in primary culture, PSC changed their phenotype from fat-storing to SMA-positive myofibroblast-like cells expressing platelet-derived growth factor (PDGF) alpha- and PDGF beta-receptors. TGF-beta(1) and tumor necrosis factor (TNF)-alpha accelerated the change in the cells' phenotype. Addition of 50 ng/ml PDGF and 5 ng/ml basic fibroblast growth factor (bFGF) to cultured PSC significantly stimulated cell proliferation (4.37 +/- 0.49- and 2.96 +/- 0.39-fold of control). Fibronectin synthesis calculated on the basis of DNA was stimulated by 5 ng/ml bFGF (3.44 +/- 1.13-fold), 5 ng/ml TGF-beta(1) (2.46 +/- 0.89-fold), 20 ng/ml PDGF (2.27 +/- 0.68-fold), and 50 ng/ml TGF-alpha (1.87 +/- 0.19-fold). As shown by RT-PCR, PSC express predominantly the splice variant EIII-A of fibronectin. Immunofluorescence microscopy and Northern blot confirmed that in particular bFGF and TGF-beta(1) stimulated the synthesis of fibronectin and collagens type I and III. In conclusion, our data demonstrate that 1) TGF-beta(1) and TNF-alpha accelerate the change in the cell phenotype, 2) PDGF represents the most effective mitogen, and 3) bFGF, TGF-beta(1), PDGF, and, to a lesser extent, TGF-alpha stimulate extracellular matrix synthesis of cultured rat PSC.

A murine tumor progression model for pancreatic cancer recapitulating the genetic alterations of the human disease

This study describes a tumor progression model for ductal pancreatic cancer in mice overexpressing TGF-alpha. Activation of Ras and Erk causes induction of cyclin D1-Cdk4 without increase of cyclin E or PCNA in ductal lesions. Thus, TGF-alpha is able to promote progression throughout G1, but not S phase. Crossbreeding with p53 null mice accelerates tumor development in TGF-alpha transgenic mice dramatically. In tumors developing in these mice, biallelic deletion of Ink4a/Arf or LOH of the Smad4 locus is found suggesting that loci in addition to p53 are involved in antitumor activities. We conclude that these genetic events are critical for pancreatic tumor formation in mice. This model recapitulates pathomorphological features and genetic alterations of the human disease.

Metabolic and weight loss effects of long-term dietary intervention in obese patients: four-year results

OBJECTIVE

To investigate the contribution of meal and snack replacements for long-term weight maintenance and risk factor reduction in obese patients.

RESEARCH METHODS AND PROCEDURES

Prospective, randomized, two-arm, parallel intervention for 12 weeks followed by a prospective single-arm 4-year trial in a University Hospital clinic. One hundred patients, >18 years old and with a body mass index > 25 and < or = 40 kg/m2, were prescribed a 1,200 to 1,500 kcal/d control diet (Group A) or an isoenergetic diet, including two meal and snack replacements (vitamin- and mineral-fortified shakes, soups, and bars) and one meal high in fruits and vegetables (Group B). Following a 3 months of weight loss, all patients were prescribed the same energy-restricted diet (1,200 to 1,500 kcal) with one meal and one snack replacement for an additional 4 years.

RESULTS

All 100 patients were evaluated at 12 weeks. Mean percentage weight loss was 1.5 +/- 0.4% and 7.8 +/- 0.5% (mean +/- SEM) for Groups A and B, respectively. At 12 weeks systolic blood pressure, plasma triacylglycerol, glucose, and insulin concentrations were significantly reduced in Group B, whereas no changes occurred in Group A. After 4 years, 75% of the patients were evaluated. Total mean weight loss was 3.2 +/- 0.8% for Group A and 8.4 +/- 0.8% (mean +/- SEM) for Group B. Both groups showed significant improvement in blood glucose and insulin (p < 0.001), but only Group B showed significant improvement in triacylglycerol and systolic blood pressure compared to baseline values (p < 0.001).

DISCUSSION

Providing a structured meal plan via vitamin- and mineral-fortified liquid meal replacements is a safe and effective dietary strategy for obese patients. Long-term maintenance of weight loss with meal replacements can improve certain biomarkers of disease risk.

Prospective evaluation of brush cytology of biliary strictures during endoscopic retrograde cholangiopancreatography

BACKGROUND AND STUDY AIMS

Cytological methods may be used to differentiate benign from malignant biliary strictures. We evaluated the diagnostic accuracy of an endobiliary cytotechnique which can easily be performed during endoscopic retrograde cholangiopancreatography.

PATIENTS AND METHODS

Cytological samples were obtained by brushing biliary strictures via a guide wire in 86 patients with strictures of unknown status. Samples were classified by an expert cytologist as normal (including reactive cells), severely dysplastic (atypical cells suspicious of malignancy) and clearly malignant. A final diagnosis was achieved in 78 patients based on intraoperative findings and histological investigation, autopsy or prolonged follow-up. Strictures were malignant in 57 cases (31 pancreatic carcinoma, 20 cholangiocarcinoma, 6 others) and benign in 21 cases (11 chronic pancreatitis, 5 chronic nonspecific inflammation, 5 others).

RESULTS

The overall results for brush cytological investigation were sensitivity 56.1%, specificity 90.5%, positive predictive value 94.1%, negative predictive value 43.2 %, and accuracy 65.4 %. Sensitivity was significantly higher (P<0.005) in cholangiocarcinoma (80%) compared with pancreatic carcinoma (35.5%). The overall specificity of less than 100 % resulted from dysplasia in two patients with chronic pancreatitis and inflammatory mass. No procedure-related complications occurred.

CONCLUSIONS

Brush cytology is helpful for differentiating between benign and malignant biliary strictures, especially in suspected cholangiocarcinoma. Dysplastic cells may occur in the absence of malignancy and their presence should therefore be interpreted cautiously.

Platelet-derived growth factors stimulate proliferation and extracellular matrix synthesis of pancreatic stellate cells: implications in pathogenesis of pancreas fibrosis

At present, the cell-cell interactions and molecular mechanisms of pancreas fibrogenesis are largely unknown. The purpose of this study was to investigate paracrine stimulatory loops between platelets and pancreatic stellate cells (PSC). Human PSC were obtained by outgrowth from fibrotic human pancreas. Native platelet lysate (nPL) and transiently acidified platelet lysate (aPL) were added to cultured PSC (passage 4 to 7) in the absence of serum. The synthesis of collagen types I and III and c-fibronectin (cFN) was demonstrated on protein (immunofluorescence and quantitative immunoassay) and mRNA (Northern blot) level. Using sections of human pancreas with acute pancreatitis, platelet aggregates in capillaries were demonstrated by transmission electron microscopy. nPL, and to an even greater extent aPL, significantly increased the synthesis of collagen types I and III and of c-FN (120 microl/ml aPL increased collagen type I concentration in PSC supernatants by 1.99 +/- 0.17 times and c-FN of 2.49 +/- 0.28 times, mean +/- SD, n = 3). nPL and aPL also significantly stimulated cell proliferation (increased bromodeoxyuridine (BrdU) incorporation by 6.4 +/- 0.78 times and 10 +/- 0.29 times, respectively). By preincubating aPL with transforming growth factor beta (TGFbeta)- and platelet-derived growth factor (PDGF)-neutralizing antibodies and the TGFbeta-latency associated peptide, respectively, TGFbeta1 was identified as the main mediator stimulating matrix synthesis and PDGF as the responsible mitogen. Our data demonstrate that platelets contain fibrogenic mediators that stimulate proliferation (PDGF) and matrix synthesis (TGFbeta1) of cultured PSC. We suggest that platelets and PSC cooperate in the development of pancreas fibrosis.

Molecular cloning and characterization of the human protein kinase D2. A novel member of the protein kinase D family of serine threonine kinases

We have isolated the full-length cDNA of a novel human serine threonine protein kinase gene. The deduced protein sequence contains two cysteine-rich motifs at the N terminus, a pleckstrin homology domain, and a catalytic domain containing all the characteristic sequence motifs of serine protein kinases. It exhibits the strongest homology to the serine threonine protein kinases PKD/PKCmicro and PKCnu, particularly in the duplex zinc finger-like cysteine-rich motif, in the pleckstrin homology domain and in the protein kinase domain. In contrast, it shows only a low degree of sequence similarity to other members of the PKC family. Therefore, the new protein has been termed protein kinase D2 (PKD2). The mRNA of PKD2 is widely expressed in human and murine tissues. It encodes a protein with a molecular mass of 105 kDa in SDS-polyacrylamide gel electrophoresis, which is expressed in various human cell lines, including HL60 cells, which do not express PKCmicro. In vivo phorbol ester binding studies demonstrated a concentration-dependent binding of [(3)H]phorbol 12,13-dibutyrate to PKD2. The addition of phorbol 12,13-dibutyrate in the presence of dioleoylphosphatidylserine stimulated the autophosphorylation of PKD2 in a synergistic fashion. Phorbol esters also stimulated autophosphorylation of PKD2 in intact cells. PKD2 activated by phorbol esters efficiently phosphorylated the exogenous substrate histone H1. In addition, we could identify the C-terminal Ser(876) residue as an in vivo phosphorylation site within PKD2. Phosphorylation of Ser(876) of PKD2 correlated with the activation status of the kinase. Finally, gastrin was found to be a physiological activator of PKD2 in human AGS-B cells stably transfected with the CCK(B)/gastrin receptor. Thus, PKD2 is a novel phorbol ester- and growth factor-stimulated protein kinase.

Expression of the highly conserved RNA binding protein KOC in embryogenesis

The human KOC gene which is highly expressed in cancer shows typical structural features of an RNA binding protein. We analyzed the temporal and spatial expression pattern of KOC in mouse embryos at different gestational ages. The expression of KOC seems to be ubiquitous at early stages. During advanced gestation highest KOC expression occurs in the gut, pancreas, kidney, and in the developing brain. The expression pattern of KOC was compared to its Xenopus homologue Vg1-RBP during frog development. Similar expression was found in these organs suggesting an important functional role of the homologous proteins in embryonic development.

Malignant transformation of duct-like cells originating from acini in transforming growth factor transgenic mice

BACKGROUND & AIMS

In transgenic mice overexpressing transforming growth factor (TGF)-alpha in the exocrine pancreas, progressive pancreatic fibrosis and a transdifferentiation of acinar cells to duct-like cells occurs. The present study was undertaken to analyze this transdifferentiation process.

METHODS

Pancreatic specimens were characterized using light microscopy and immunohistochemistry. Expression of the epidermal growth factor receptor (EGFR) and TGF-alpha was evaluated with slot blot and Western analysis. To identify other generic events, K-ras mutations were screened with an enriched polymerase chain reaction approach and p53 expression was detected with immunohistochemistry.

RESULTS

Morphological examination revealed an aggregation of interlobular fibroblasts and a decrease in acinar cell height starting at day 14 after birth. In older animals, these acinar cells change to duct-like cells, which form tubular structures and express ductal markers. Evidence for dysplastic changes was found in 12 of 21 TGF-alpha transgenic mice older than 1 year. We also observed four malignant pancreatic tumors, which were multicentric and originated from dysplastic tubular complexes. They displayed a mixed cystic-papillary phenotype strongly positive for carbonic anhydrase activity. EGFR expression progressively increased in the transition from acinar to duct-like and transformed cells. Activating K-ras mutations could not be detected; however, tubular complexes and tumors displayed increased immunoreactivity for nuclear p53.

CONCLUSIONS

These data suggest an involvement of the TGF-alpha/EGFR pathway in conjunction with other yet unknown events in pancreatic tumor development. Furthermore, these observations are in favor of an acinar-ductal carcinoma sequence. Thus, these transgenic animals will be useful to define genetic alterations associated with a transition from acinar cells to a neoplastic ductal phenotype.

A randomised, double blind, multicentre trial of octreotide in moderate to severe acute pancreatitis

BACKGROUND

The pharmacological inhibition of exocrine pancreatic secretion with the somatostatin analogue octreotide has been advocated as a specific treatment of acute pancreatitis.

AIM

To investigate the efficacy of octreotide in acute pancreatitis in a randomised, placebo controlled trial.

METHODS

302 patients from 32 hospitals, fulfilling the criteria for moderate to severe acute pancreatitis within 96 hours of the onset of symptoms, were randomly assigned to one of three treatment groups: group P (n=103) received placebo, while groups O1 (n=98) and O2 (n=101) received 100 and 200 microg of octreotide, respectively, by subcutaneous injection three times daily for seven days. The primary outcome variable was a score composed of mortality and 15 typical complications of acute pancreatitis.

RESULTS

The three groups were well matched with respect to pretreatment characteristics. An intent to treat analysis of all 302 patients revealed no significant differences among treatment groups with respect to mortality (P: 16%; O1: 15%; O2: 12%), the rate of newly developed complications, the duration of pain, surgical interventions, or the length of the hospital stay. A valid for efficacy analysis (251 patients) also revealed no significant differences.

CONCLUSIONS

This trial shows no benefit of octreotide in the treatment of acute pancreatitis.

High prevalence of osteoporotic vertebral fractures in patients with Crohn's disease

BACKGROUND AND AIMS

Osteopenia and osteoporosis are frequent in Crohn's disease. However, there are few data on related vertebral fractures. Therefore, we evaluated prospectively the prevalence of osteoporotic vertebral fractures in these patients.

METHODS

A total of 293 patients were screened with dual energy x ray absorptiometry of the lumbar spine (L1-L4) and proximal right femur. In 156 patients with lumbar osteopenia or osteoporosis (T score <-1), x ray examinations of the thoracic and lumbar spine were performed. Assessment of fractures included visual reading of x rays and quantitative morphometry of the vertebral bodies (T4-L4), analogous to the criteria of the European Vertebral Osteoporosis Study.

RESULTS

In 34 (21.8%; 18 female) of 156 Crohn's disease patients with reduced bone mineral density, 63 osteoporotic vertebral fractures (50 fx. (osteoporotic fracture with visible fracture line running into the vertebral body and/or change of outer shape) and 13 fxd. (osteoporotic fracture with change of outer shape but without visible fracture line)) were found, 50 fx. in 25 (16%, 15 female) patients and 13 fxd. in nine (5.8%, three female) patients. In four patients the fractures were clinically evident and associated with severe back pain. Approximately one third of patients with fractures were younger than 30 years. Lumbar bone mineral density was significantly reduced in patients with fractures compared with those without (T score -2.50 (0.88) v -2.07 (0.66); p<0.025) but not at the hip (-2.0 (1.1) v -1.81 (0.87); p=0.38). In subgroups analyses, no significant differences were observed.

CONCLUSIONS

In patients with Crohn's disease and reduced bone mineral density, the prevalence of vertebral fractures-that is, manifest osteoporosis-was strikingly high at 22%, even in those aged less than 30 years, a problem deserving further clinical attention.

Role of MT-MMPs and MMP-2 in pancreatic cancer progression

Activation of matrix metalloproteinase-2 (MMP-2) by the membrane-type matrix metalloproteinases (MT-MMPs) has been associated with tumor progression. In the present study, we examined the role of MMP-2 and its activators MT1-MMP, MT2-MMP and MT3-MMP in pancreatic tumor cell invasion and the development of the desmoplastic reaction characteristic of pancreatic cancer tissues. Northern blot analyses revealed that transcript levels of MT1-MMP and MT2-MMP, but not MT3-MMP, were enhanced in pancreatic cancer tissues (n = 18) compared with both chronic pancreatitis (n = 9) and healthy pancreas (n = 9). A good correlation was found between MT1-MMP and both MMP-2 expression (p < 0.01) and activity in pancreatic cancer tissues. In addition, expression and activation of MMP-2 were strongly associated with the extent of the desmoplastic reaction in pancreatic cancer tissues. Invasion assays showed a good correlation between MMP-2 expression and activity and the invasive potential of pancreatic cancer cell lines. In cell lines with high levels of MMP-2 expression and activity, the MMP inhibitor Batimastat led to significant reduction of the number of invading cells. Our results suggest that MT1-MMP is involved in the progression of pancreatic cancer via activation of MMP-2. MMP-2 itself plays an important role in tumor cell invasion and appears to be associated with the development of the characteristic desmoplastic reaction in pancreatic cancer.

Expression and differential regulation of connective tissue growth factor in pancreatic cancer cells

CTGF is an immediate early growth responsive gene that has been shown to be a downstream mediator of TGFbeta actions in fibroblasts and vascular endothelial cells. In the present study hCTGF was isolated as immediate early target gene of EGF/TGFalpha in human pancreatic cancer cells by suppression hybridization. CTGF transcripts were found in 13/15 pancreatic cancer cell lines incubated with 10% serum. In 3/7 pancreatic cancer cell lines EGF/TGFalpha induced a significant rise of CTGF transcript levels peaking 1-2 h after the start of treatment. TGFbeta increased CTGF transcript levels in 2/7 pancreatic cancer cell lines after 4 h of treatment and this elevation was sustained after 24 h. Only treatment with TGFbeta was accompanied by a parallel induction of collagen type I transcription. 15/19 human pancreatic cancer tissues were shown to overexpress high levels of CTGF transcripts. CTGF transcript levels in pancreatic cancer tissues and nude mouse xenograft tumors showed a good correlation to the degree of fibrosis. In situ hybridization and the nude mouse experiments revealed that in pancreatic cancer tissues, fibroblasts are the predominant site of CTGF transcription, whereas the tumor cells appear to contribute to a lesser extent. We conclude that CTGF may be of paramount importance for the development of the characteristic desmoplastic reaction in pancreatic cancer tissues.