azaserine and camostat

We examined the pattern of expression of several proto-oncogenes during nonneoplastic growth and in acinar cell neoplasms in the rat pancreas. The levels of c-myc, c-raf-1, and c-Ki-ras mRNAs were increased in regenerating pancreata following surgical partial pancreatectomy and following administration of camostat. We also investigated proto-oncogene expression associated with the progression of pancreatic cancers in azaserine-treated rats. Injection of a single dose (30 mg/kg) of azaserine (O-diazoacetyl-L-serine) to 14-d-old rats leads to a variety of neoplastic lesions in the rat pancreas. Total RNA was isolated from lesions in various stages of tumor progression, including adenomas, carcinomas in situ, and invasive carcinomas. We observed increased expression of c-myc, c-raf-1, and c-Ki-ras in azaserine-induced adenomas and carcinomas. Actin expression was also increased in these tissues, whereas amylase expression was variable. However, when compared to the normal growing pancreas, the level of proto-oncogene expression in the adenomas and carcinomas was disproportionate to the degree of cellular division in those tissues. Thus, the alterations induced by azaserine apparently caused a deregulated increase in expression of cellular oncogenes associated with growth regulation.

Topics: Adenoma; Animals; Azaserine; Blotting, Northern; Carcinoma; Cell Cycle; Esters; Gabexate; Gene Expression; Guanidines; Mitotic Index; Pancreas; Pancreatic Neoplasms; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-myc; Proto-Oncogene Proteins c-raf; Proto-Oncogene Proteins p21(ras); Proto-Oncogenes; Rats; Rats, Inbred Lew; Regeneration; RNA, Neoplasm

Feeding of raw soya flour or other trypsin inhibitors such as camostate is a well-established method for promoting growth of (pre)neoplastic foci induced in the exocrine pancreas of rats by azaserine. The effect of trypsin inhibitors is thought to be mediated through an increased release of cholecystokinin. Using the specific cholecystokinin receptor antagonist lorglumide (CR-1409), we performed a 16-wk study to investigate the potential of this drug in inhibiting growth of putative preneoplastic foci and to determine whether and to what extent cholecystokinin is responsible for the effect of trypsin inhibitors on pancreatic growth. After initiation with 30 mg/kg of azaserine at 19 days of age, six groups of 15 rats each received one of the following treatments: camostate, cholecystokinin-8, or gelatin control, either or not in combination with CR-1409, once daily, 3 days wk for 16 wk. Plasma cholecystokinin levels, measured 30 min after the stimulus, were similar after camostate and cholecystokinin octapeptide administration. After 16 wk the pancreata were removed, weighted, and quantitatively analyzed for the number and size of putative preneoplastic foci by light microscopy. Both camostate and cholecystokinin octapeptide stimulated pancreatic growth and development of acidophilic putative preneoplastic foci, whereas growth of basophilic putative preneoplastic foci was inhibited by camostate but stimulated by cholecystokinin. CR-1409 almost completely abolished the effect of cholecystokinin and was found to cause a significant decrease in the effects of camostate. It is concluded that (a) cholecystokinin plays a significant role in camostate-stimulated growth of acidophilic putative preneoplastic foci in rat pancreas and (b) CR-1409 inhibits growth of putative preneoplastic foci induced in rat pancreas by azaserine and hence may be of potential value for the treatment of pancreatic cancer in humans.

Topics: Animals; Azaserine; Cholecystokinin; Esters; Gabexate; Glutamine; Guanidines; Male; Pancreatic Neoplasms; Precancerous Conditions; Proglumide; Rats; Rats, Inbred Strains; Receptors, Cholecystokinin; Sincalide; Trypsin Inhibitors

The effects of dietary camostate (FOY-305), a synthetic trypsin inhibitor, on the early stages of pancreatic carcinogenesis in the rat were studied because of earlier reports that feeding soy bean trypsin inhibitor stimulated growth and promoted carcinogenesis in the pancreas of rats. These effects are attributed to excess secretion of cholecystokinin, a trophic hormone for pancreatic acinar cells. Camostate has been shown to induce pancreatic enlargement in rats by the same mechanism. In preliminary experiments, pancreatic growth was studied in adult Fischer 344 (F344) and Lewis rats fed camostate mixed in the diet to define a level that induced pancreatic hypertrophy and hyperplasia. As little as 0.02% fed 3 days per week was effective. In a second experiment, F344 rats were injected with azaserine and thereafter were given camostate by gavage 5 days a week until autopsy 18 weeks later. In a third experiment, azaserine-treated Lewis rats were fed camostate in the diet 3 days a week for 8 or 16 weeks until autopsy. In the latter two experiments the number and size of atypical acinar cell foci and nodules (AACN) were measured in pancreas sections. Growth of acidophilic AACN was stimulated in camostate-fed groups; both the number and the size were increased in comparison with the control groups. The data suggest a promoting effect of dietary camostate on the growth of azaserine-induced preneoplastic lesions in the pancreas of both rat strains. The number of basophilic AACN was decreased in camostate-fed Lewis rats suggesting that the camostate diet also affected the phenotype of the carcinogen-induced AACN.

Topics: Animals; Azaserine; Carcinogens; Cell Division; Diet; Esters; Gabexate; Guanidines; Pancreas; Pancreatic Neoplasms; Protease Inhibitors; Rats; Rats, Inbred F344; Rats, Inbred Lew