Ralf Jesnowski

Gene expression profiles of microdissected pancreatic ductal adenocarcinoma

In a search for new molecular markers of pancreatic ductal adenocarcinoma (PDAC), we compared the gene expression profiles of seven pancreatic carcinomas and one carcinoma of the papilla Vateri with those of duct cells from three non-neoplastic pancreatic tissues. In addition, the human pancreatic duct cell line and five PDAC cell lines (AsPC-1, BxPC-3, Capan-1, Capan-2, HPAF) were examined. RNA was extracted from microdissected tissue or cultured cell lines and analysed using a custom-made Affymetrix Chip containing 3023 genes, of which 1000 were known to be tumour associated. Hierarchical clustering revealed 81 differentially expressed genes. Of all the genes, 26 were downregulated in PDAC and 14 were upregulated in PDAC. In PDAC cell lines versus normal pancreatic duct cells, 21 genes were downregulated and 20 were upregulated. Of these 81 differentially expressed genes, 15 represented human genes previously implicated in the tumourigenesis of PDAC. From the genes that were so far not known to be associated with PDAC tumorigenesis, we selected ADAM9 for further validation because of its distinct overexpression in tumour tissue. Using immunohistochemistry, the over-expressed gene, ADAM9, was present in 70% of the PDACs analysed. In conclusion, using microarray technology we were able to identify a set of genes whose aberrant expression was associated with PDAC and may be used to target the disease.

Autoantibodies against the exocrine pancreas in autoimmune pancreatitis: gene and protein expression profiling and immunoassays identify pancreatic enzymes as a major target of the inflammatory process

OBJECTIVES:Autoimmune pancreatitis (AIP) is thought to be an immune-mediated inflammatory process, directed against the epithelial components of the pancreas. The objective was to identify novel markers of disease and to unravel the pathogenesis of AIP.METHODS:To explore key targets of the inflammatory process, we analyzed the expression of proteins at the RNA and protein level using genomics and proteomics, immunohistochemistry, western blot, and immunoassay. An animal model of AIP with LP-BM5 murine leukemia virus-infected mice was studied in parallel. RNA microarrays of pancreatic tissue from 12 patients with AIP were compared with those of 8 patients with non-AIP chronic pancreatitis.RESULTS:Expression profiling showed 272 upregulated genes, including those encoding for immunoglobulins, chemokines and their receptors, and 86 downregulated genes, including those for pancreatic proteases such as three trypsinogen isoforms. Protein profiling showed that the expression of trypsinogens and other pancreatic enzymes was greatly reduced. Immunohistochemistry showed a near-loss of trypsin-positive acinar cells, which was also confirmed by western blotting. The serum of AIP patients contained high titers of autoantibodies against the trypsinogens PRSS1 and PRSS2 but not against PRSS3. In addition, there were autoantibodies against the trypsin inhibitor PSTI (the product of the SPINK1 gene). In the pancreas of AIP animals, we found similar protein patterns and a reduction in trypsinogen.CONCLUSIONS:These data indicate that the immune-mediated process characterizing AIP involves pancreatic acinar cells and their secretory enzymes such as trypsin isoforms. Demonstration of trypsinogen autoantibodies may be helpful for the diagnosis of AIP.

Targeted chemotherapy by intratumour injection of encapsulated cells engineered to produce CYP2B1, an ifosfamide activating cytochrome P450.

The prognosis of pancreatic adenocarcinoma is poor and current treatment ineffective. A novel treatment strategy is described here using a mouse model system for pancreatic cancer. Cells that have been genetically modified to express the cytochrome P450 2B1 enzyme are encapsulated in cellulose sulphate and implanted into pre-established tumours derived from human pancreatic cells. Cytochrome P450 2B1 converts the chemotherapeutic agent ifosfamide to toxic metabolites. Administration of ifosfamide to tumour-bearing mice that were recipients of implanted encapsulated cells results in partial or even complete tumour ablation. These results suggest that in situ chemotherapy with genetically modified cells in an immunoprotected environment may prove useful for application in man.

Immortalization of pancreatic stellate cells as an in vitro model of pancreatic fibrosis: deactivation is induced by matrigel and N-acetylcysteine

Tissue fibrosis is one of the characteristics of chronic pancreatitis and pancreatic adenocarcinoma. Activated pancreatic stellate cells (PSC) play a central role in this process. However, analysis of the molecular mechanisms leading to PSC activation is hampered by the lack of an established human PSC line. To overcome this problem, we immortalized and characterized primary human PSC. The cells were isolated by the outgrowth method and were immortalized by transfection with SV40 large T antigen and human telomerase (hTERT). Primary human PSC served as controls. An immortalized line, RLT-PSC, was analyzed for the expression of stellate cell markers. Moreover, the effects of transforming growth factor β 1(TGFβ1) or platelet-derived growth factor stimulation and of cultivation on basement membrane components or N-acetylcysteine (NAC) treatment on gene and protein expression and proliferation were analyzed. Immortal RLT-PSC cells retained the phenotype of activated PSC proven by the expression of α-smooth muscle actin (αSMA), vimentin, desmin and glial fibrillary acidic protein (GFAP). TGFβ1 treatment upregulated the expression of αSMA, collagen type I (Col I), fibronectin and TGFβ1. Incubation of RLT-PSC cells and primary human activated PSC on Matrigel plus NAC treatment resulted in a deactivated phenotype as evidenced by a decrease of αSMA, connective tissue growth factor and Col I expression and by a decreased proliferation of the cells. Moreover, this treatment restored the ability of the cells to store vitamin A in cytoplasmic vesicles. In conclusion, we have established an immortal pancreatic stellate cell line, without changing the characteristic phenotype. Importantly, we were able to demonstrate that besides soluble factors, the matrix surrounding PSC plays a pivotal role in the maintenance of the activation process of PSC. Cultivation of activated PSC on a reconstituted basement membrane plus treatment with NAC was able to deactivate the cells, thus pointing to the possibility of an antifibrosis therapy in chronic pancreatitis.

Activation of Wnt signalling in stroma from pancreatic cancer identified by gene expression profiling

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an abundant desmoplastic stroma. Interactions between cancer and stromal cells play a critical role in tumour invasion, metastasis and chemoresistance. Therefore, we hypothesized that gene expression profile of the stromal components of pancreatic carcinoma is different from chronic pancreatitis and reflects the interaction with the tumour. We investigated the gene expression of eleven stromal tissues from PDAC, nine from chronic pancreatitis and cell lines of stromal origin using the Affymetrix U133 GeneChip set. The tissue samples were microdissected, the RNA was extracted, amplified and labelled using a repetitive in vitro transcription protocol. Differentially expressed genes were identified and validated using quantitative RT‐PCR and immuno‐histochemistry. We found 255 genes to be overexpressed and 61 genes to be underexpressed within the stroma of pancreatic carcinoma compared to the stroma of chronic pancreatitis. Analysis of the involved signal transduction pathways revealed a number of genes associated with the Wnt pathway of which the differential expression of SFRP1 and WNT5a was confirmed using immunohistochemistry. Moreover, we could demonstrate that WNT5a expression was induced in fibroblasts during cocultivation with a pancreatic carcinoma cell line. The identified differences in the expression profile of stroma cells derived from tumour compared to cells of inflammatory origin suggest a specific response of the tissue surrounding malignant cells. The overexpression of WNT5a, a gene involved in the non canonical Wnt signalling and chondrocyte development might contribute to the strong desmoplastic reaction seen in pancreatic cancer.

ATP-Binding Cassette C Transporters in Human Pancreatic Carcinoma Cell Lines

Background: Pancreatic cancer is characterized by high resistance to chemotherapy. Such chemoresistance can be mediated by multidrug resistance proteins (MRPs), breast cancer resistance protein (BCRP), and MDR1 P-glycoprotein. However, the contribution of individual MRP isoforms to chemoresistance in pancreatic carcinoma is unclear. We studied ATP-binding cassette (ABC) transporter expression in human pancreatic carcinoma cell lines as compared to primary pancreatic duct cells, and analyzed the MRP expression profile in 5-fluorouracil-resistant cells. Methods: Transporter expression was analyzed by quantitative and qualitative RT-PCR, by immunoblot, and chemoresistance by cytotoxicity assay. Results: Primary pancreatic duct cells expressed MRP1, MRP3, MRP4, and MRP5, but not MRP2 mRNA. The established carcinoma cell lines expressed MRP1, MRP4, and MRP5, most of them also MRP2, MRP3, MRP7, and BCRP, but none contained detectable amounts of MRP6, MRP8, or MRP9 mRNA. Immunoblot analyses demonstrated presence of MRP1, MRP4, and MRP5 protein in all, but MRP3 and BCRP protein only in some of these cells. Compared to parental Capan-1 cells, Capan-1 cells with acquired chemoresistance towards 5-fluorouracil showed an upregulated mRNA and protein expression of MRP3, MRP4, and MRP5. In addition, silencing of MRP5 by RNA interference resulted in enhanced sensitivity of parental Capan-1 cells towards 5-fluorouracil cytotoxicity. Conclusion: MRP3, MRP4, and MRP5 are upregulated in 5-fluorouracil-resistant cells, and MRP5 contributes to 5-FU resistance in pancreatic carcinoma cells.

Cell therapy using microencapsulated 293 cells transfected with a gene construct expressing CYP2B1, an ifosfamide converting enzyme, instilled intra-arterially in patients with advanced-stage pancreatic carcinoma: a phase I/II study.

Matthias Lohr (principal investigator) · Zoltan Tibor Bago · Helga Bergmeister · Manfred Ceijna · Mathias Freund · Wolfgang Gelbmann · Walter H. Gunzburg · Ralf Jesnowski · Johannes Hain · Karlheinz Hauenstein Wolfgang Henninger · Anne Hoffmeyer · Peter Karle · Jens-Christian Kroger · Gunther Kundt · Stefan Liebe Udo Losert · Petra Muller · Alexander Probst · Katrin Puschel · Matthias Renner · Renate Renz · Robert Saller Brian Salmons · Maximilian Schuh · Ilse Schwendenwein · Kerstin von Rombs · Thomas Wagner · Ingrid Walter (coinvestigators)

Gene expression analysis of pancreatic cell lines reveals genes overexpressed in pancreatic cancer

Background: Pancreatic cancer is one of the leading causes of cancer-related death. Using DNA gene expression analysis based on a custom made Affymetrix cancer array, we investigated the expression pattern of both primary and established pancreatic carcinoma cell lines. Methods: We analyzed the gene expression of 5 established pancreatic cancer cell lines (AsPC-1, BxPC-3, Capan-1, Capan-2 and HPAF II) and 5 primary isolates, 1 of them derived from benign pancreatic duct cells. Results: Out of 1,540 genes which were expressed in at least 3 experiments, we found 122 genes upregulated and 18 downregulated in tumor cell lines compared to benign cells with a fold change >3. Several of the upregulated genes (like Prefoldin 5, ADAM9 and E-cadherin) have been associated with pancreatic cancer before. The other differentially regulated genes, however, play a so far unknown role in the course of human pancreatic carcinoma. By means of immunohistochemistry we could show that thymosin β-10 (TMSB10), upregulated in tumor cell lines, is expressed in human pancreatic carcinoma, but not in non-neoplastic pancreatic tissue, suggesting a role for TMSB10 in the carcinogenesis of pancreatic carcinoma. Conclusion: Using gene expression profiling of pancreatic cell lines we were able to identify genes differentially expressed in pancreatic adenocarcinoma, which might contribute to pancreatic cancer development.

EXPRESSION OF CANCER TESTIS ANTIGENS IN PANCREATIC CARCINOMA CELL LINES, PANCREATIC ADENOCARCINOMA AND CHRONIC PANCREATITIS

In order to define antigens that might be suitable as vaccines for pancreatic carcinoma, we investigated the composite expression of 10 cancer testis (CT) antigens (SCP‐1, NY‐ESO‐1, SSX‐1, SSX‐2, SSX‐4, GAGE, MAGE‐3, MAGE‐4, CT‐7 and CT‐8) by Reverse Transcriptase‐PCR (RT‐PCR) in fresh biopsies of human pancreatic adenocarcinoma, chronic pancreatitis and pancreatic carcinoma cell lines. While all CT genes were frequently expressed in cell lines derived from pancreatic cancer, no expression of MAGE‐3, SSX‐1, SSX‐2, NY‐ESO‐1 and CT‐7 was detected in fresh tumor biopsies, and MAGE‐4 (1/52), SSX‐4 (1/39) and CT‐8 (2/41) were only rarely expressed. In contrast, HOM‐TES‐14/SCP‐1 was expressed in 48% (29/61) and GAGE in 21% (13/61) of cases, respectively. One CT gene was expressed by 59% (75% in male, 46% in female patients; p = 0.05) and 2 or more CT genes by 15% of the samples. SCP‐1 protein expression correlated well with mRNA expression. While SCP‐1 and GAGE were absent in normal pancreas, they were found in 2/8 (SCP‐1) and 1/8 (GAGE) samples of chronic pancreatitis, respectively, supporting the concept of chronic pancreatitis as a premalignant condition. SCP‐1 and GAGE represent promising candidates for vaccine development in pancreatic carcinoma. Whether SCP‐1 and GAGE expression identify cases of chronic pancreatitis with a high risk of malignant transformation remains to be shown.

Aberrant Expression of a Disintegrin and Metalloproteinase 17/Tumor Necrosis Factor-α Converting Enzyme Increases the Malignant Potential in Human Pancreatic Ductal Adenocarcinoma

A disintegrin and metalloproteinase (ADAM) molecules are known for their unique potential to combine adhesion, proteolysis, and signaling. To understand the role of ADAM17/tumor necrosis factor-alpha (TNF-alpha) converting enzyme (TACE) in pancreatic ductal adenocarcinoma (PDAC), we investigated its expression, function, and in vitro regulation. ADAM17/TACE mRNA was expressed in 3 of 10 normal pancreatic tissues, 6 of 8 samples from patients with chronic pancreatitis, 10 of 10 PDAC tissues, and 9 of 9 pancreatic cancer cell lines, but it was absent in primary duct epithelial cells. Immunohistochemical staining revealed positive cancer cells in 8 of 10 PDACs but no staining of ducts in normal pancreas. ADAM17/TACE was found in 0 of 16 pancreatic intraepithelial neoplasia (PanIN)-1A lesions, 1 of 30 PanIN-1B lesions, 2 of 13 PanIN-2 lesions but, in 13 of 15 PanIN-3 lesions, associated with PDAC. Western blot, flow cytometry, and confocal microscopy analyses showed the aberrant expression of ADAM17/TACE protein in pancreatic cancer cell lines. The proteolytic activity of ADAM17/TACE, assessed by the release of TNF-alpha, was inhibited by TNF-alpha protease inhibitor. ADAM17/TACE gene silencing using small interfering RNA technique in vitro reduced invasion behavior dramatically, whereas proliferation was unaffected. Furthermore, ADAM17/TACE mRNA expression was down-regulated in pancreatic cancer cells arrested in G2-M phase as well as in a time-dependent manner after TNF-alpha and interleukin-6 incubation. In conclusion, our findings provide evidence of aberrant expression of the proteolytically active ADAM17/TACE in advanced precursor lesions (PanIN-3) and PDAC while identifying its critical involvement in the invasion process.