Matthias B. Schneider

Expression of Nerve Growth Factors in Pancreatic Neural Tissue and Pancreatic Cancer

One of the characteristics of pancreatic cancer is its tendency to invade neural tissue. We hypothesized that the affinity of cancer cells for nerve tissue is related to the presence of growth factors in neural tissue and their receptors in cancer cells. Sections of pancreatic cancer and normal pancreatic tissue were examined by immunohistochemistry for the expression of the neurotrophins NGF, BDNF, NT-3, NT-4, and their receptors TrkA, TrkB, and TrkC, as well as the low-affinity receptor, p75NTR. TrkA expression was found in duct, islet, and cancer cells; TrkB was found in the α-cells of the islet only. The anti-pan-Trk antibody (TrkB3), which is presumed to recognize all three receptors, immunoreacted with duct and acinar cells in normal tissue and with cancer cells. The staining with TrkC was similar to that of TrkA. The low-affinity receptor p75NTR was expressed in the neural tissue and in scattered duct cells of the normal tissue only. Duct and acinar cells, as well as neural tissue and cancer cells, showed weak to strong immunoreactivity with NGF. NT-3 expression was noted in capillary endothelia and erythrocytes. NT-4 showed specific staining for ductule cells. The expression and distribution of neurotrophins and their receptors suggest their role in the potential of pancreatic cancer cells for neural invasion.

Pancreatic Cell Lines: A Review

Pancreatic cancer has an extremely poor prognosis and lacks early diagnostic and therapeutic possibilities, mainly because of its silent course and explosive fatal outcome. The histogenesis of the disease and early biochemical and genetic alterations surrounding carcinogenesis are still controversial. In vitro studies offer a useful tool to study physiologic, pathophysiologic, differentiation, and transformation processes of cells and to understand some of these shortcomings. The extreme difficulties in isolating individual pancreatic cells and their purification by maintaining their native characteristics have limited research in this area. This review is intended to present and discuss the current availability of rodent and pancreatic cell lines, their differences as well as the difficulties, limitations, and characteristics of these cultured cells. Discussed are in vitro models; ductal, islet, and acinar cell culture; cell differentiation; cell transformation, including genetic and chromosomal alterations; as well as tumor cell markers. Also addressed are the advantages and problems associated with the cell culture in humans and rodents. Advancements in tissue culture technique and molecular biology offer steady progress in this important line of research. The improved methods not only promise the establishment of &bgr;-cell cultures for the treatment of diabetes, but also for studying sequential genetic alterations during pancreatic carcinogenesis and in understanding the tumor cell origin.

Experimental Animal Models in Pancreatic Carcinogenesis: Lessons for Human Pancreatic Cancer

The silent course of pancreatic cancer and its explosive fatal outcome have hindered studies of tumor histogenesis and the identification of early biochemical and genetic alterations that could help to diagnose the disease at a curable stage and develop therapeutic strategies. Experimental animal models provide important tools to assess risk factors, as well as preventive and therapeutic possibilities. Although several pancreatic cancer models presently exist, only models that closely resemble human tumors in morphological, clinical, and biological aspects present useful media for preclinical studies. Because an estimated 70% of human tumors are induced by carcinogens and because a significant association has been found between cigarette smoking and pancreatic cancer, chemically induced models are of particular value. Moreover, in such models the etiology, modifying factors, effects of diets, and naturally occurring products can be studied and early diagnostic, preventive, and therapeutic possibilities sought out. Many of the existing models are described in this review, and the advantages and shortcomings of each model and their clinical implications are discussed.

Differences in the expression of glutathione S-transferases in normal pancreas, chronic pancreatitis, secondary chronic pancreatitis, and pancreatic cancer.

Introduction In our previous study, glutathione S-transferase-&pgr; (GST-&pgr;), a phase II drug metabolizing enzyme, was found to be expressed in pancreatic ductal and ductular cells but not acinar cells of the normal pancreas, chronic pancreatitis, and secondary pancreatitis caused by pancreatic cancer. A greater percentage of the cells expressing GST-&pgr; was shown in the islets of chronic pancreatitis specimens compared with the normal pancreas and secondary pancreatitis. Aims and Methodology To examine whether the increased number of islet cells expressing GST-&pgr; and the absence in the acinar cells are compensated for by other GST isozymes, we investigated the expression of GST-&agr; and GST-&mgr; in the same specimens. Results Unlike the distribution of GST-&pgr;, the distribution of GST-&agr; and GST-&mgr; in islets did not show marked differences between the three groups. However, in four of 18 primary chronic pancreatitis specimens, more islet cells (approximately 25%) expressed GST-&agr; than in the normal pancreas and secondary chronic pancreatitis (both approximately 10%). The reactivity of cancer cells to GST-&agr;, GST-&mgr;, and GST-&pgr; was similar to the ductal cells in the normal pancreas, chronic pancreatitis, and secondary chronic pancreatitis. Contrary to the expression of GST-&pgr;, no statistically significant differences were found in the distribution of GST-&agr; and GST-&mgr; in the normal pancreas, chronic pancreatitis, and secondary chronic pancreatitis. Conclusion The expression of the other GSTs does not compensate for the variation of expression of GST-&pgr;. There was no specimen in each group that did not express at least one GST isozyme in islet, acinar, and ductal cells.

Expression of drug-metabolizing enzymes in the pancreas of hamster, mouse, and rat, responding differently to the pancreatic carcinogenicity of BOP

Background/Methods: N-nitroso-bis(2-oxopropyl)amine (BOP) induces pancreatic ductal adenocarcinoma in Syrian golden hamsters, but not in rats or mice. To examine whether this difference is due to the diversity in the presence and distribution of enzymes involved in the metabolism of BOP, the cellular expression of nine cytochrome P-450 isozymes (CYP1A1, CYP1A2, CYP2B6, CYP2C8,9,19, CYP2D1, CYP2E1, CYP3A1, CYP3A2, and CYP3A4) and of three glutathione S-transferase isozymes (GST-π, GST-α, and GST-µ) was investigated in the pancreas of hamsters, rats, and mice by immunohistochemistry. Results: We found a wide species variation in the presence and cellular localization of the enzymes and a lack of several enzymes, including GST-α in islets, CYP2B6, CYP2C8,9,19, CYP3A1 in acinar cells, and CYP3A4 in ductal cells, in the rat as compared with hamster and mouse. Conclusion: Although the results could not clarify the reasons for the species differences in the pancreatic carcinogenicity of BOP, the presence of most of the cytochrome P-450 isozymes in pancreatic islets of all three species highlights the important role of the islets in drug metabolism.

Differences in the Expression of Xenobiotic-Metabolizing Enzymes between Islets Derived from the Ventral and Dorsal Anlage of the Pancreas

Background/Aims: Chronic pancreatitis and pancreatic cancer have been linked to the exposure of environmental chemicals (xenobiotics), which generally require metabolic activation to highly reactive toxic or carcinogenic intermediates. The primary enzyme system involved is made up of numerous cytochrome P450 mono-oxygenases (CYP). Glutathione S-transferases (GST) belong to the enzyme systems that catalyze the conjugation of the reactive intermediates produced by CYPs to less toxic or readily excretable metabolites. Because the majority of chronic pancreatitis and pancreatic cancers develop in the organ’s head, we compared the expression of selected CYP and GST enzymes between the tissues deriving from the ventral anlage (head) and dorsal anlage (corpus, tail). Methods: A total of 20 normal pancreatic tissue specimen from organ donors and early autopsy cases were processed immunohistochemically by using antibodies to CYP 1A1, 1A2, 2B6, 2C8/9/19, 2D6, 2E1, 3A1, 3A2 and 3A4, GST-α, GST-µ and GST-π, and the NADPH cytochrome P450 oxido-reductase (NA-OR), the specificity of which has been verified in our previous study by Western blot and RT-PCR analyses. Results: In all pancreatic regions, most of the enzymes were expressed in islet cells. However, more islets in the head region expressed CYP 2B6, 2C8/9/19, 2E1 and the NA-OR, than those in the body and tail. Moreover, the expression of CYP 2B6 and 2E1 was restricted to the pancreatic polypeptide (PP) cells, and the concentration of CYP 3A1 and 3A4 was stronger in PP cells than in other islet cells. On the other hand, GST-µ and GST-π were expressed primarily in islet cells of the body and tail. Conclusion: The greater content of xenobiotic-metabolizing and carcinogen-activating CYP enzymes and a lower expression of detoxifying GST enzymes in the head of the pancreas could be one reason for the greater susceptibility of this region for inflammatory and malignant diseases.

Pacinian corpuscle in the human pancreas.

During our systematic examination of the distribution of cytochrome P450 enzymes in the normal and diseased human pancreas, we observed a Pacinian corpuscle in a serial section of a tissue from a pancreatic cancer patient. We report the histologic and immunohistochemical patterns in this corpuscle and review the literature. The Pacinian corpuscle was situated within the pancreas of a 76-year-old woman with cancer in the head of the pancreas. We could demonstrate immunoreactivity within the corpuscle for the neurofilament protein, neuron-specific enolase, S-100 Protein, and for four cytochrome P450-isozymes. The possible function of Pacinian corpuscles in the mammalian and human pancreas is discussed.

ErbB2 growth factor receptor, a marker for neuroendocrine cells?

Background/Aims: The overexpression of ErbB2 in pancreatic cancer has been reported with a varying incidence ranging between 1 and 80%. Our routine examination, however, revealed a consistently strong immunoreactivity of three anti-ErbB2 growth factor receptor antibodies in pancreatic islets and intrapancreatic ganglia. To validate our findings and to understand the reasons for the reported differences in the frequency of ErbB2 overexpression in pancreatic cancer, the following studies were performed. Materials and Methods: Tissue samples from 12 normal pancreata, 7 surgical chronic pancreatitis cases, 21 primary pancreatic adenocarcinomas, 9 metastatic pancreatic adenocarcinomas, and 4 islet cell tumors were subjected to immunohistochemical examination using antibodies from three manufacturers. Cultured human islet cells and pancreatic cancer cell lines, as well as samples from the gastrointestinal tract, the CNS, and the adrenal gland were included in the study. For comparison, mammary cancer tissue and mammary cancer cells, as well as selected tissues from Syrian golden hamsters, were used. To verify the results, Western blot and Northern slot-blot analyses were performed. Results: Pancreatic cancer cells, in vitro and in vivo, showed a remarkable heterogeneity in the immunostaining of ErbB2, ranging from very faintly to strongly stained. On the other hand, in both humans and hamsters, a consistently strong immunostaining was found in the Langerhans’ islets, in the ganglia of intrapancreatic and extrapancreatic nerves, as well as in the CNS, spinal cord and adrenal gland. Conclusions: ErbB2 appears to play an important role in neuroendocrine tissues and is probably involved in the development and functional regulation of these cells. The concomitant expression of these factors and islet cell hormones very likely results in the activation of multiple growth-promoting pathways in pancreatic cancer and its aggressive behavior.

LAPSG Society News

The LAPSG is a multidisciplinary group dedicated to the study of the biology, pathophysiology and disease of the endocrine and exocrine pancreas. In particular the fi elds of gastroenterology, endocrinology, oncology, surgery, pharmacology, cell and molecular biology, nutrition, immunology and epidemiology will receive attention. It is also the study group’s aim to enhance the communication among scientists from different areas (especially the fi elds of gastroenterology and endocrinology) who otherwise rarely meet. The means to achieve these goals will be meetings of the members, postgraduate courses, clinical-research workshops and symposia. Pancreatologists and those working in related areas that live and work in Latin America, and who have published at least once during the last 5 years, are warmly invited to join the LAPSG. Members of the LAPSG will automatically become members of the International Association of Pancreatology (IAP) and the European Pancreatic Club (EPC) and will get a free online and print subscription to the journal Pancreatology.

Unterschiedliche Verteilung von Fremdstoff-metabolisierenden Enzymen in der ventralen und dorsalen Pankreasanlage

Umwelttoxine und -karzinogene spielen eine massgebliche Rolle in der Pathogenese des Pankreaskarzinoms. Die Aktivierung von endo- und exogenen (Pra-) Karzinogenen erfolgt in > 90% uber ein Cytochrom P450 (CYP) abhangiges Enzymsystem (Tabelle 1). Aktivierte Karzinogene werden von nachgeschalteten Glutathion S-Transferasen (GST) metabolisiert und deaktiviert. Die Verteilung und Aktivitat dieser Enzyme unterliegen einer grossen interindividuellen Variabilitat. Da 4/5 aller Pankreaskarzinome im Kopfbereich des Organs lokalisiert sind, war es Ziel dieser Studie Unterschiede in der Verteilung von Karzinogen-metabolisierenden Enzymen in der ventralen (Kopf) und dorsalen (Corpus-, Schwanzbereich) Pankreasanlage zu untersuchen.