Early changes in regenerating hamster pancreas following a single dose of N-nitrosobis (2-oxopropyl)amine (NBOP) administered at the peak of DNA synthesis

Membrane biochemistry and chemical hepatocarcinogenesis

Biochemical membrane alterations appearing during the process of chemical carcinogenesis are described. Emphasis is put on membrane composition, structure, and biogenesis. In this presentation the knowledge gained from experimental studies of liver and skin in the process of cancer development is acknowledged. Important biochemical changes have been reported in lipid composition, fatty acid saturation, constitutional enzyme expression, receptor turnover and oligomerization. Functional consequences of the altered membrane structure is discussed within the concepts of regulation of cell proliferation, regulation of membrane receptor expression, redox control, signal transduction, drug metabolism, and multidrug resistance. Data from malignant tumours and normal tissue are addressed to evaluate the importance of the alterations for the process and for the eventual malignant transformation.

The effect of gastrointestinal hormones on the incorporation of tritiated thymidine in the pancreatic adenocarcinoma cell line (WD PaCa)

In view of the trophic action of gastrointestinal hormones on the exocrine pancreas, the effects of secretin, octapeptide of cholecystokinin (CCK-8), and desglugastrin on the growth of hamster pancreatic well differentiated adenocarcinoma were investigated in vitro. Desglugastrin exhibited the greatest effect on thymidine incorporation into these cells after a lag period of 96 h. Doses of desglugastrin in the range from 30 to 270 ng/mL caused a significant and dose-dependent increase in thymidine incorporation. Higher doses of this peptide led to a decreased response. Secretin also increased thymidine incorporation, but the response was less than that induced by gastrin. Prolonged incubation with secretin for 96 h increased tritiated thymidine incorporation in a log-dose fashion in the range of 30 to 270 ng/mL. Doses of CCK-8 in the range of 90 to 810 ng/mL significantly increased thymidine incorporation after 48 h of incubation. Following 72 h of incubation, only the dose of 270 ng/mL continued to exhibit a significant stimulation. Our study suggests that the gastrointestinal hormones could directly increase the growth of pancreatic carcinoma cells, act synergistically with endogenous growth factors, or stimulate the local production of these factors. In any event, our results that gastrin, secretin, and CCK can stimulate the growth of pancreatic ductal tumor cells in tissue cultures, support earlier findings on normal and malignant pancreatic parenchyma.

Focal eosinophilic hypertrophic cells of the rat pancreas

Focal spontaneously occurring eosinophilic hypertrophic cells, histomorphologically resembling oncocytes and hepatocytes, were observed in the pancreas from 11 (0.3%) of 4,177 Sprague-Dawley rats, 3 to 26 months old. The age of these eleven rats ranged from 13 to 25 months. The incidence was not different between sexes. The altered cells were usually seen in the peri-insular area. Two types of foci, uniform and pleomorphic, were classified on the basis of uniformity of size of the altered cells within a focus. The origin and nature were not determined for the altered cells/foci reported in this study but they were not considered to be neoplastic.

Histogenesis of pancreatic carcinomas: a study based on 248 cases

Primary pancreatic carcinomas were studied histologically and histochemically, to assess the frequency of ductal hyperplasia in tissue adjacent to malignant neoplasms. Hyperplasia was divided into four types: simple, papillary, atypical and ductular, affecting large, medium and small ducts (ductules). All types of hyperplasia were frequently seen in areas adjacent to carcinomas, including ductal, pleomorphic, mucinous, adenosquamous, small and spindle cell and cystadenocarcinomas. In contrast, acinar cell carcinoma and microadenocarcinoma were less frequently associated with ductal hyperplasia. Mucin histochemistry revealed differences in types of mucin between the normal ducts and hyperplastic pancreatic ducts and carcinomas. The former group contained small amounts of sulphated mucin while the latter showed a marked increase in neutral and sialomucins. Our study also suggests that both papillary and atypical hyperplasia are precancerous lesions, supporting an hypothesis of ductal origin of pancreatic carcinomas.

Expression of oncofoetal pancreatic antigens in hamster adult pancreas during experimental carcinogenesis

Foetal acinar components associated with the development of the hamster pancreas have been previously defined with the aid of an antifoetal pancreas serum. In immunohistology this antiserum also stained malignant ductal cells in N-nitrobis (2-oxopropyl) amine (BOP)-induced pancreatic adenocarcinoma. It did not stain adult pancreas structures including acini, ducts and islets of Langerhans. In this study, re-expression of foetal acinar antigens was disclosed before formation of tumours. Adenocarcinomas were not detected by conventional histology before the 24th week following initiation of the chemical treatment. However, staining with the antiserum was observed from the 7th week appearing in the apex of some acini cells having an almost normal histological appearance. Later, foetal acinar expression was frequently associated with evident morphological alterations in acini like dyskaryosis, enlarged cytoplasm or lumina. Staining of ducts with marked atypical epithelium and (as already reported) of neoplastic ducts was also observed. It was not detected in other pancreatic lesions viz. cystadenomas, mucoid glands and regular hyperplastic ducts. Acinar dedifferentiation as assessed by expression of foetal components preceded formation of tumours in all instances.