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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies were conducted to evaluate the possibility of a bile reflux mechanism in the etiology of induced pancreatic cancer. N-Nitrosobis(2-oxopropyl)amine (BOP) was administered to Syrian hamsters after partial pancreatico-colostomy. Either the gastric or the splenic lobe of the pancreas was anastomosed to the transverse colon in groups 1 and 2, respectively. Group 3 were sham-operated controls and group 4 were controls without surgery. Shortly after surgery all 4 groups received a single subcutaneous BOP injection (20 mg/kg body weight) and survivors were sacrificed 46 weeks after BOP treatment. BOP-induced pancreatic tumor patterns were not altered by pancreatico-colostomy when compared with those in sham-operated controls. In all BOP-treated hamsters the number and distribution of benign and malignant lesions were similar in each individual pancreatic segment, including the anastomosed lobe (A-lobe); some hamsters developed tumors only in the A-lobe. As in other pancreatic regions, the initial hyperplasia in the A-lobe primarily affected peri- and intra-insular ductules and less frequently involved the ducts. These findings support the theory that the carcinogen is bloodborne and indicate that BOP-responsive pancreatic cells are distributed on a volume basis in distinct proportions within the pancreatic segments. As in previous experiments a higher incidence of pancreatic neoplasms was found in BOP-treated controls (those not operated upon) than in partially pancreatico-colostomized hamsters, including those with sham operations. Hyperplastic and dyplastic development of colonic mucosa around the anastomosis could be related to a local effect of carcinogen or of its metabolites, which are known to be excreted via pancreatic secretions.
Carcinogenesis 1983 Oct
PMID:Modification of pancreatic carcinogenesis in the hamster model. 5. Effect of partial pancreatico-colostomy. 661 62

Liver preparations from Syrian golden hamsters catalyze the metabolism of the pancreatic carcinogen N-nitroso-2,6-dimethylmorpholine largely to N-nitroso(2-hydroxypropyl)(2-oxopropyl)amine (HPOP). This reaction is catalyzed by a mixed-function oxidase in the presence of reduced nicotinamide adenine dinucleotide phosphate and oxygen at a rate of 3.8 nmol/min/mg of protein, and it is inhibited by known cytochrome P-450-specific inhibitors. A second potent pancreatic carcinogen N-nitrosobis(2-oxopropyl)amine (BOP) is converted to HPOP by hamster liver in which two enzyme systems appear to be involved. The first is a reductase associated with microsomes which reduces BOP to HPOP in the presence of reduced nicotinamide adenine dinucleotide at a rate of 9.1 nmol/min/mg of protein. The second enzyme is a cytosolic one which catalyzes the same reaction at a slower rate (2.3 nmol/min/mg of protein) and is more effective with reduced nicotinamide adenine dinucleotide phosphate as cofactor. Based on the amount of protein in hepatic cytosol and endoplasmic reticulum, the two enzymes may be involved to a similar extent in the reduction of BOP to HPOP in the liver. Pancreas, on the other hand, lacks the microsomal reductase for BOP but contains a cytosolic enzyme which catalyzes its reduction in the presence of reduced nicotinamide adenine dinucleotide phosphate at a rate of 0.35 nmol/min/mg of protein. Since both pancreatic carcinogens N-nitroso-2,6-dimethylmorpholine and BOP are metabolized to HPOP in the liver at rates much higher than those observed in the target organ pancreas, it is suggested that the liver may play an important role in pancreatic carcinogenesis in the hamster by these compounds.
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PMID:Metabolism of pancreatic carcinogens N-nitroso-2,6-dimethylmorpholine and N-nitrosobis(2-oxopropyl)amine by microsomes and cytosol of hamster pancreas and liver. 664 May 29

The reduction of N-nitrosobis(2-oxopropyl)amine (BOP) and N-nitroso(2-oxopropyl)propylamine (NOPPA) by hepatic and pancreatic cytosol and microsomes from Syrian golden hamsters and Sprague-Dawley rats has been examined. All hepatic fractions reduced both substrates, although the activity depended on the fraction tested and the cofactor employed (NADH or NADPH). Generally, hamster hepatic fractions contained higher activity than the rat hepatic fractions and BOP was a better substrate than NOPPA. Of the pancreatic fractions, only cytosol exhibited reductase activity. The hamster cytosol was able to utilise both cofactors, but the rat fraction exhibited activity only when NADPH was present. BOP was the better substrate for the pancreatic enzymes and in the presence of NADPH, the rat and hamster activities were about equal. These results suggest that the pancreatic reduction of BOP to HPOP is unlikely to be a significant factor in the species-specific induction of pancreatic cancer by BOP.
Carcinogenesis 1983 Nov
PMID:Enzymatic reduction of beta-ketonitrosamines. 664 Aug 48

The effect of ligation and excision of the pancreatic duct in pancreatic carcinogenesis was examined in the hamster model. Animals were treated with a single dose (20 mg/kg body weight) of N-nitrosobis(2-oxopropyl)amine (BOP) either immediately (Group 1) or on Days 1 (Group 2), 3 (Group 3) or 7 (Group 4) after ligation and excision of the duct of the splenic lobe. Group 5 received BOP shortly after laparoscopy, and Group 6 consisted of BOP-treated controls. All hamsters were killed 46 weeks after BOP treatment. The results showed that despite advanced atrophy of the splenic lobe distal to the excised duct in Groups 1-4, some hamsters in Groups 2, 3, and 4 showed hyperplasia, dysplasia, and increased mitotic activities of ductal and ductular cells. However, carcinomas in the duct-excised atrophic lobe were found only in Groups 1-3. These data indicate that BOP carcinogenesis is mediated through blood circulation, and that cancer development is not inhibited in the duct-excised lobe for up to 3 days after surgery. However, in the entire pancreas, a significant reduction in tumor incidence was seen when the carcinogen was given immediately, or to a lesser extent, 1 day after surgery, regardless of whether or not excision was made. On the contrary, BOP, when given 3 and 7 days after duct excision, enhanced tumor development in the nonexcised (intact) pancreas, compared with other test groups and with BOP controls. Both inhibition and enhancement seemed due to a proportional decrease and increase, respectively, of BOP-responsive cells throughout the intact pancreas.
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PMID:Modification of pancreatic carcinogenesis in the hamster model. 6. The effect of ductal ligation and excision. 665 Jun 65

N-Nitrosobis(2-oxopropyl)amine (BOP), N-nitrosobis(2-hydroxypropyl)-amine (BHP) and N-nitroso(2-hydroxypropyl-2-oxopropyl)amine (HPOP) are pancreatic carcinogens in the Syrian golden hamster (SGH) but do not cause pancreatic tumors in rats. In this study, the ability of these three compounds to induce DNA damage in isolated pancreas cells from both species was determined by alkaline elution analysis. BOP was highly potent in SGH cells, causing DNA damage at concentrations as low as 0.5 micrograms/ml, and HPOP, although less potent than BOP, also caused considerable damage. Isolated SGH pancreas cells are thus able to metabolize BOP and HPOP to DNA-damaging species. Of the three compounds tested, only HPOP at higher doses (25-100 micrograms/ml) induced DNA damage in isolated rat pancreas cells. BHP did not damage rat or SGH pancreas cell DNA at concentrations up to 100 micrograms/ml, apparently due to lack of uptake of this compound by the cells. The observed insensitivity to DNA damage in rat cells is consistent with the resistance of the rat pancreas to carcinogenesis by these three compounds. The sensitivity of SGH pancreas cells to BOP- and HPOP-induced DNA damage correlates with the high carcinogenicity of these compounds for the SGH pancreas.
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PMID:DNA damage in isolated hamster and rat pancreas cells by pancreatic carcinogens. 669 95

Alloxan, when given intravenously at a dose of 60 mg/kg body weight 2 hours prior to subcutaneous injection of the potent pancreatic carcinogen N-nitrosobis (2-oxopropyl) amine (BOP), inhibited the induction of hyperplastic and neoplastic pancreatic lesions in a statistically significant fashion (P less than 0.01). The number of lesions per animal affected was markedly less in these animals, compared with BOP-treated control animals. BOP administration 2 weeks after alloxan treatment, at which time pancreatic islet cell regeneration is considered completed, did not alter either the incidence or number of lesions. The results support our view that the pancreatic islet cells are the primary source of BOP metabolism. The concomitant inhibition of gallbladder tumors, but not of common duct neoplasms, in hamsters receiving BOP 2 hours after alloxan could indicate that alloxan's inhibitory effects on BOP carcinogenesis are not restricted to the pancreas.
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PMID:Modification of pancreatic carcinogenesis in the hamster model. 3. Inhibitory effect of alloxan. 682 9

Pancreatic carcinogenesis was investigated in outbred and in five strains of inbred Syrian golden hamsters utilizing the nitrosamines N-nitrosobis(2-hydroxypropyl)amine (BHP) and N-nitrosobis(2-oxopropyl)amine (BOP). Thirty eight outbred hamsters were treated for an average of 15 weeks with weekly s.c. inoculations of BHP at doses of 250,000 or 1000 mg/kg. Pancreatic carcinomas developed in 19%. Eighty nine inbred hamsters of strains CB, LHC and PD4 were given BHP at 250 mg/kg weekly for an average of 25 weeks. Pancreatic carcinomas developed in 61%. Pancreatic inflammation, fibrosis, and ductal hyperplasia were prominent. Toxic changes in the liver, biliary hyperplasia, and pulmonary interstitial inflammation were also prominent features of BHP-treated hamsters, along with occasional carcinomas of the liver and respiratory tract. One hundred and sixteen inbred hamsters of strains CB, LHC, LSH, MHA, and PD4 were treated with BOP at a dose of 5 mg/kg weekly for 15 weeks. The incidence of pancreatic carcinoma was 51%. BHP-treated hamsters exhibited pancreatic fibrosis and ductal hyperplasia. Livers of BHP-treated animals showed biliary hyperplasia, and lungs exhibited chronic inflammation. Occasional carcinomas of the liver and lung developed. From 243 hamsters treated with nitroso carcinogens, eight pancreatic ductal adenocarcinoma lines were derived that can be transplanted and propagated in inbred hamsters.
Carcinogenesis 1982
PMID:Nitrosamine-induced pancreatic carcinogenesis in outbred and inbred Syrian hamsters. 713 56

After injection of N-nitrosobis(2-oxopropyl)amine (BOP) (10 mg/kg) to male Syrian golden hamsters there were there concentrations of BOP and many of its metabolites in the hamster pancreas compared with the liver and salivary gland. Also, a potential methylating metabolite of BOP, N-nitrosomethyl(2-oxopropyl)amine, was found in both tissues.
Carcinogenesis 1981
PMID:The formation of N-nitrosomethyl(2-oxopropyl)amine from N-nitrosobis(2-oxopropyl)amine in vivo. 729 69

The synthetic dithiolethione Oltipraz has marked cancer chemopreventive and phase II enzyme inducing activity in various animal carcinogenesis models, but has not been examined in any animal models of ductal pancreatic cancer relevant to the human disease. The chemopreventive potential of Oltipraz on pancreatic tumor incidence and multiplicity was examined in the N-nitrosobis(2-oxopropyl)-amine (BOP)-induced ductal pancreatic adenocarcinoma model in Syrian hamsters. Animals were maintained on control semipurified diets or semipurified diets containing 300 and 600 mg/kg Oltipraz beginning 2 weeks prior to BOP initiation and throughout the 26 week study. Oltipraz at 300 mg/kg had no effect on the incidence or multiplicity of preneoplastic, neoplastic or metastatic lesions, while at 600 mg/kg dietary Oltipraz the incidence of pancreatic adenocarcinomas was reduced significantly (P < or = 0.05) compared to BOP-treated controls. Dietary Oltipraz at both doses had a significant influence on reducing mortality and morbidity in tumor-bearing animals with metastatic disease. At 26 weeks, total hepatic glutathione-S transferase (GST) activity and GST mu activity were elevated significantly in Oltipraz-treated animals, while total pancreatic GST activity was reduced, albeit not significantly. Serum lipase activity, a marker for pancreatic damage, exhibited a progressive decline in BOP-treated animals administered Oltipraz compared to BOP-treated controls at 12 weeks of the study; by week 26, lipase activity was comparable in all groups and reduced compared to activity at week 12. Positive nuclear immunostaining for the p53 tumor suppressor protein, a hallmark of human pancreatic cancer and a transient response to DNA damage, was observed in only a small percentage of BOP-induced pancreatic lesions and was not influenced Oltipraz administration. Further chemoprevention and pharmacologic studies of Oltipraz in relevant animal models of ductal pancreatic cancer could provide a foundation for future studies in human populations at potential risk for pancreatic cancer.
Carcinogenesis 1995 Sep
PMID:Chemopreventive activity of Oltipraz against N-nitrosobis(2-oxopropyl)amine (BOP)-induced ductal pancreatic carcinoma development and effects on survival of Syrian golden hamsters. 755 69

In the present study the chemopreventive potential of 25% fat (HF) diets containing 2 wt% linoleic acid (LA) and including 0.0, 1.2, 2.4, 4.7, 7.1 or 9.4 wt% dietary fish oil (MaxEPA) has been investigated using the N-nitrosobis(2-oxopropyl)amine (BOP)-hamster model for pancreatic cancer. The number of pancreatic borderline lesions (BLL) was significantly higher (P < 0.05) in the HF groups containing 1.2, 2.4 or 9.4 wt% MaxEPA in comparison with the HF group without MaxEPA. MaxEPA inhibited the metabolism of LA to arachidonic acid (AA) and of AA to prostaglandins (PGs) in both blood plasma and pancreatic microsomes. The pancreatic levels of PGE2 (P < 0.05), 6-keto-PGF1 alpha (P < 0.01) and PGF2 alpha (P < 0.05) decreased significantly with increasing dietary MaxEPA. The levels of PGE2 (P < 0.001), 6-keto-PGF1 alpha (P < 0.05), PGF2 alpha (P < 0.001) and thromboxane (TX) B2 (P < 0.001) in pancreatic adenocarcinomas were higher than in non-tumorous pancreas. The MaxEPA had no significant effect on the BrdU labeling index (LI) in acinar, ductular or centroacinar cells, nor on the LI in BOP-induced pancreatic lesions. It is concluded that (i) dietary fish oil has a slight enhancing effect on BOP-induced pancreatic carcinogenesis in hamsters and (ii) dietary fish oil dose-dependently inhibits the conversion of LA to AA and of AA to certain PGs and (iii) dietary fish oil does not influence the cell proliferation in hamster pancreas.
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PMID:Effects of dietary fish oil (MaxEPA) on N-nitrosobis(2-oxopropyl)amine (BOP)-induced pancreatic carcinogenesis in hamsters. 763 46


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