Early diagnosis of pancreatic cancer: neutrophil gelatinase-associated lipocalin as a marker of pancreatic intraepithelial neoplasia.

Pancreatic cancer is a highly lethal malignancy with a dismal 5-year survival of less than 5%. The scarcity of early biomarkers has considerably hindered our ability to launch preventive measures for this malignancy in a timely manner. Neutrophil gelatinase-associated lipocalin (NGAL), a 24-kDa glycoprotein, was reported to be upregulated nearly 27-fold in pancreatic cancer cells compared to normal ductal cells in a microarray analysis. Given the need for biomarkers in the early diagnosis of pancreatic cancer, we investigated the expression of NGAL in tissues with the objective of examining if NGAL immunostaining could be used to identify foci of pancreatic intraepithelial neoplasia, premalignant lesions preceding invasive cancer. To examine a possible correlation between NGAL expression and the degree of differentiation, we also analysed NGAL levels in pancreatic cancer cell lines with varying grades of differentiation. Although NGAL expression was strongly upregulated in pancreatic cancer, and moderately in pancreatitis, only a weak expression could be detected in the healthy pancreas. The average composite score for adenocarcinoma (4.26+/-2.44) was significantly higher than that for the normal pancreas (1.0) or pancreatitis (1.0) (P<0.0001). Further, although both well- and moderately differentiated pancreatic cancer were positive for NGAL, poorly differentiated adenocarcinoma was uniformly negative. Importantly, NGAL expression was detected as early as the PanIN-1 stage, suggesting that it could be a marker of the earliest premalignant changes in the pancreas. Further, we examined NGAL levels in serum samples. Serum NGAL levels were above the cutoff for healthy individuals in 94% of pancreatic cancer and 62.5% each of acute and chronic pancreatitis samples. However, the difference between NGAL levels in pancreatitis and pancreatic cancer was not significant. A ROC curve analysis revealed that ELISA for NGAL is fairly accurate in distinguishing pancreatic cancer from non-cancer cases (area under curve=0.75). In conclusion, NGAL is highly expressed in early dysplastic lesions in the pancreas, suggesting a possible role as an early diagnostic marker for pancreatic cancer. Further, serum NGAL measurement could be investigated as a possible biomarker in pancreatitis and pancreatic adenocarcinoma.

Retinoic acid can induce markers of endocrine transdifferentiation in pancreatic ductal adenocarcinoma: preliminary observations from an in vitro cell line model.

BACKGROUND AND HYPOTHESIS: The pancreatic ductal adenocarcinoma (HPAF) cells have a multipotent stem cell potential. It was hypothesised that all-trans-retinoic acid (atRA) can induce transdifferentiation of these cells into cells with an endocrine phenotype. MATERIAL AND METHODS: To explore this hypothesis, an in vitro system of cells was established. Some cells were treated with atRA at concentrations of 100 nmol/l (non-apoptosis-inducing) and 5 micromol/l (apoptosis-inducing) and harvested. Cells were examined for cell cycle kinetics, apoptosis (terminal deoxynucleotidyl transferase assay and p53 protein expression) and immunomorphological features of redifferentiation (MUC1 and DUPAN-2) and endocrine transdifferentiation (insulin, somatostatin, glucagon, neurone-specific enolase) by using immunoperoxidase staining methods. Levels of insulin, transforming growth factor (TGF) beta2, TGFalpha and epidermal growth factor receptor (EGFR) were measured by enzyme-linked immunosorbent assay (ELISA). The vehicle-treated cells served as a control group. RESULTS: When compared with untreated cells, cells treated with 100 nmol/l and 5 micromol/l atRA were observed to show (1) decreased proliferative activity (cpm) as indicated by decreased incorporation of thymidine labelled with hydrogen-3; (2) cell cycle arrest; (3) increased apoptotic activity associated with p53 protein overexpression; (4) upregulated expression of the transdifferentiation and redifferentiation markers; (5) morphological changes indicative of transdifferentiation (increased cell size and appearance of dendrites); (6) decreased production of EGFR; (7) upregulation of TGFalpha and TGFbeta2; and (8) increase in basal and glucose-induced insulin secretion. CONCLUSIONS: Functional endocrine transdifferentiation can be induced in HPAF lines by atRA. Further investigations are mandated to explore the underlying mechanisms of this transdifferentiation and to explore its in vivo extrapolation.

Modification of pancreatic carcinogenesis in the hamster model. VIII. Inhibitory effect of exogenous insulin.

The effect of exogenous insulin, which has been known to suppress beta-cell function of islets, was investigated on pancreatic carcinogenesis induced by N-nitrosobis(2-oxopropyl) amine [(BOP) CAS: 60599-38-4; 2,2'-dioxo-N-nitrosodipropylamine]. Three groups of Syrian golden hamsters were treated sc once with BOP (20 mg/kg body wt) simultaneously with (group 1), 120 minutes before (group 2), or 120 minutes after (group 3) a single sc injection of porcine insulin (5 U/kg body wt). Group 4 was a BOP-treated control. Survivors were killed 46 weeks after BOP administration, and the pancreas, common duct, and gallbladder were examined histologically. When given 120 minutes before or after BOP, insulin inhibited the induction of benign and malignant pancreatic lesions in a statistically significant fashion. However, the simultaneous administration of BOP also led to similar (although not statistically significant) results as did the administration of insulin 120 minutes after BOP. Insulin also seemed to inhibit tumor induction in the common duct and gallbladder, regardless of when it was administered; however, the differing incidence was statistically significant only in hamsters from group 3 killed at the experiment's end. The overall data suggest that the inhibitory effect of exogenous insulin on pancreatic carcinogenicity is not merely through islet cells, but rather through other (or additional) mechanisms.

Effects of the interaction of dietary fat and protein on N-nitrosobis(2-oxopropyl)amine-induced carcinogenesis and spontaneous lesions in Syrian golden hamsters.

Syrian golden hamsters were fed four diets in experiments designed to evaluate the effects of the interaction of dietary fat and protein on carcinogenesis induced by N-nitrosobis(2-oxopropyl)amine [(BOP) CAS: 60599-38-4]. The diets consisted of two levels of dietary fat [4.5 g (low fat, LF) or 18 g (high fat, HF) of corn oil/385 kilocalories (kcal)]. These levels were fed with each of two levels of dietary protein [9 g low-protein (LP) and 36 g high-protein (HP) casein/385 kcal]. The four diets were fed to two separate groups of hamsters at two different periods in their life-span. For testing of the effects of diet on tumor initiation, one group received the diets from 3 to 7 weeks of age. At 8 weeks, they were given injections sc of 10 mg BOP/kg body weight and placed on a control diet [9 g corn oil (medium fat) and 18 g casein (medium protein)/385 kcal]. The other group received control diet until 8 weeks of age, at which time they were given injections of BOP and placed on the four diets. This group was designed to test the effects of the diets on tumor development. BOP-induced lesions in the lungs, liver, common bile duct, gallbladder, and kidneys are described; results in the pancreas were reported separately. In hamsters fed the four diets after BOP treatment, the LF-LP groups had the fewest tumors, the LF-HP-fed and HF-LP-fed groups had intermediate yields of tumors, and the hamsters given HF-HP diet exhibited the largest numbers of neoplasms. Several specific tumor types showed a similar pattern. For example, the pulmonary adenoma incidence, which was low in the non-BOP-treated hamsters, was higher in the HF-HP group than in those fed LF-HP diet after BOP, but it was not influenced by fat at the LP level. In addition, renal adenomas were observed at a low incidence in non-BOP-treated hamsters and in hamsters fed LF-LP levels before or after BOP treatment (0.5% incidence) but were present at an 8% incidence in all other BOP-treated groups. The incidence of biliary cystic adenomas was highest in male hamsters that received HF diets, irrespective of BOP treatment, and BOP treatment resulted in increased yields of this lesion in females only in groups given HF-LP diet.(ABSTRACT TRUNCATED AT 400 WORDS)

Interaction of dietary fat and protein in spontaneous diseases of Syrian golden hamsters.

The influence of interactions between dietary fat and protein on spontaneous diseases was investigated in Syrian golden hamsters fed two levels of corn oil [4.5 or 18 g/385 kilocalories (kcal)] with each of two levels of casein (9 or 36 g/385 kcal). The four diets were fed to separate groups in two different sequences: 1) Diets were given during weeks 3-7 and followed by control diet (9 g corn oil and 18 g casein/385 kcal), or 2) control diet was fed during weeks 3-7, and the four diets were fed from week 8 until death. Dietary interactions of fat and protein modified spontaneous degenerative, inflammatory, and proliferative diseases in hamsters. For example, amyloidosis in the liver, kidneys, spleen, and adrenal glands was reduced in females by feeding high-fat-high-protein (HF-HP) diet in comparison with low-fat-high-protein (LF-HP) diet during weeks 3-7 or by feeding LP diets at either fat level after 8 weeks. The incidence of hepatic abscess was highest in males consuming HP diet at either fat level after 8 weeks, and hepatic necrosis was observed most often in hamsters fed HF-HP diet after 8 weeks. Gastric and renal vascular calcification and nephrocalcinosis incidences were reduced by 50-100% in hamsters fed HF-HP diet after 8 weeks, and HF diet fed at this time reduced vascular calcification in the heart in both sexes and in the lungs in males. Inflammation was generally influenced similarly by diets fed either during weeks 3-7 or after 8 weeks. In the prostate gland, inflammation was observed most frequently in males fed HF-LP diet; however, in the vagina inflammation was elevated in females fed HF-HP diet and found in the gallbladder more commonly in hamsters fed HF-HP than in those given LF-HP. The incidence of colitis was decreased by giving HF-LP diet during weeks 3-7 or LF-LP diets after week 8. The incidence of gastric ulcer was high in males fed HF diets during weeks 3-7, and intestinal ulcers were high in those fed LF-LP at this time. The adrenal hyperplasia incidence was highest in males given HF-HP diet before or after 8 weeks and in females given this diet after 8 weeks. Similarly, ovarian and hepatic ductal hyperplasia was highest in females fed HF-HP diet after 8 weeks, and gastric and intestinal hyperplasia increased with the rise in fat at both protein levels in both sexes.(ABSTRACT TRUNCATED AT 400 WORDS)

Modification of pancreatic carcinogenesis in the hamster model. XV. Preventive effect of nicotinamide.

The induction of pancreatic ductal-ductular adenomas (P = .05) and carcinomas (P less than .0001) by N-nitrosobis(2-oxopropyl)amine [(BOP) CAS: 60599-38-4; 2,2'-dioxo-N-nitrosodipropylamine] in Syrian golden hamsters was inhibited by nicotinamide (NA) (350 mg/kg body wt, ip) administered 10 minutes before and 3 hours after a single dose of BOP (10 mg/kg body wt, sc). The anticancer effect of NA and its relatively low toxicity in humans may provide a new lead in human cancer prevention.

Prevention of N-nitrosobis(2-oxopropyl)amine-induced nasal cavity tumors in rats by orchiectomy.

Bilateral orchiectomy, performed 1 week before initiation of weekly sc injections of N-nitrosobis(2-oxopropyl)amine (BOP), prevented induction of hyperplastic and neoplastic lesions in the nasal and paranasal cavities of outbred Wistar-derived MRC rats. However, in BOP-treated rats without surgery or with bilateral vesiculectomy, the incidences of these lesions were 100 and 90%, respectively. Literature review indicates that nasal and paranasal lesions occur predominantly in male domestic animals as well as in human males and suggests a possible hormone dependency of these lesions.

Modifying factors in pancreatic carcinogenesis in the hamster model. IV. Effects of dietary protein.

The possible effects of dietary protein on pancreatic cancer induced in outbred Syrian golden hamsters by N-nitrosobis(2-oxopropyl)amine (BOP) were studied. Three levels of casein as protein at low [LP = 9 g/385 kilocalories (kcal)], medium (MP = 18 g/385 kcal), or high levels (HP = 36 g/385 kcal) were fed in two sequences to 4 groups of hamsters. The effects of protein level on the initiation phase of BOP carcinogenesis were examined in hamsters fed LP or HP from 3 through 7 weeks of age, followed by MP for the remainder of their lives. The role of protein level on the promotional (developmental) phase of carcinogenesis was evaluated in hamsters fed (from 3 through 7 wk of age) MP, followed by LP or HP for the rest of their lives. One-half of the hamsters from each of the 4 groups received a single sc BOP injection (10 mg/kg body wt) at 8 weeks of age. Changes in diet from one type to the other occurred 2 days after BOP treatment. An MP diet fed before and after BOP served as the experimental control diet. The results demonstrated that the LP diet inhibited the developmental phase of carcinogenesis only in females, whereas the MP and HP diets did not affect initiation or promotion of cancer in either sex. The inhibitory effect of the LP diet in pancreatic carcinogenicity only in females calls for further studies.

Influence of dietary fat on spontaneous lesions of Syrian golden hamsters.

Dietary corn oil was consumed by Syrian golden hamsters at levels of 4.5 g [low fat (LF)] or 18 g [high fat (HF)]/385 kilocalories (kcal) from 3 to 7 weeks of age followed by a diet containing 9 g [medium fat (MF)]/385 kcal for life. In other groups MF diet was given from 3 to 7 weeks of age and followed by either LF or HF for life. A separate group was fed MF continuously after 3 weeks of age. Spontaneous lesions, which were altered by these dietary protocols, are reported. An HF diet fed after 8 weeks increased the incidence of flank organ hyperplasia and prostatitis, but it decreased prostatic fibrosis in males. Consumption of HF diets after 8 weeks by females increased survival and resulted in an elevated incidence of thyroid adenomas, ovarian cell hyperplasia, vaginal papillomas, and adrenal cortical cell adenomas. In age-adjusted data the increase in ovarian cell hyperplasia and adrenal cortical cell adenomas was shown to be due to HF diet and not to be a consequence of extended survival. Periodontitis and calcification of cardiac tissues decreased in hamsters fed HF diets after 8 weeks, but cell vacuolization and hyperplasia of the anterior pituitary gland and epithelial hyperplasia in the forestomach were increased. Salivary gland adenocarcinomas were observed only in hamsters fed HF diets. Feeding HF levels, either during weeks 3-7 or after week 8, decreased osteofibrosis and otitis media and increased urinary bladder epithelial hyperplasia, adrenal cortical cell lipomatosis, and bone chondrosis. Calcification of gastric and renal arteries decreased as dietary fat levels increased either before or after 8 weeks of age in males and only when fed after 8 weeks in females. Colitis and focal glandular hyperplasia of the colon mucosa were increased in both sexes by an HF diet being given before or after 8 weeks of age.

Increased tumorigenesis induced by N-nitrosobis(2-oxopropyl)amine in Syrian golden hamsters fed high-fat diets.

The effects of dietary fat on carcinogenesis were presented, with the pancreas excluded, in randombred Syrian golden hamsters after administration of N-nitrosobis(2-oxopropyl)amine (BOP). Diets containing 4.5, 9, or 18 g corn oil/385 kilocalories [low-fat (LF), medium-fat (MF), or high-fat (HF) diet, respectively] were fed in two sequences. In the first sequence during which the effects of fat on the initiation phase of BOP carcinogenicity were examined, LF or HF diets were fed to hamsters 3-7 weeks of age and for 2 days after a single sc BOP treatment (10 mg/kg body wt) to 8-week-old hamsters. These hamsters were then given MF diet for the remainder of their lives. In the second sequence during which the role of fat on the promotional phase (development) of BOP-induced cancer was evaluated, MF diet was fed during the weeks preceding BOP treatment and LF or HF levels were given after BOP treatment. Separate groups were fed MF diet throughout both phases, and parallel animal groups received each diet sequence and were treated with saline at 8 weeks of age. Renal adenocarcinomas in males were observed only in those given HF diet either before or after BOP treatment (9% incidence). Similarly, pulmonary adenoma and intraphepatic biliary cystic adenoma (cholangioma) incidences were elevated above spontaneous rates in HF-fed groups. This study demonstrated that dietary fat enhanced BOP-induced tumorigenesis in the kidneys, lungs, and liver when fed, either during initiation (preceding carcinogen treatment) or at promotional stages (following carcinogen treatment).

Modification of pancreatic carcinogenesis in the hamster model. X. Effect of streptozotocin.

An experiment was conducted to examine the possibility that the carcinogenic effect on the pancreas of streptozotocin (SZ) and N-nitrosobis(2-oxopropyl)amine (BOP) is based on similar mechanisms; groups of outbred Syrian golden hamsters were treated with SZ (single iv injection, 30 mg/kg body wt) alone, BOP alone (single sc injection, 10 mg/kg body wt), and SZ and BOP simultaneously. The experiment was terminated 52 weeks after treatment began. Of the hamsters treated with SZ alone, 44% developed islet cell tumors, most of which were of pleomorphic cell types. In addition, 40% of the hamsters developed pseudoductules and 12% developed ductular adenomas. The carcinogenicity of SZ for the exocrine pancreas was further indicated by induction of ductular carcinomas by SZ plus BOP, the incidence of which was significantly higher (P less than .0001) than that induced by BOP alone.

Effect of dietary protein on N-nitrosobis(2-oxopropyl)amine-induced carcinogenesis and on spontaneous diseases in Syrian golden hamsters.

For assessment of the effect of dietary protein on spontaneous diseases and on the carcinogenicity of N-nitrosobis(2-oxopropyl)amine [(BOP) CAS: 60599-38-4], Syrian golden hamsters were fed either low protein (LP; 9% casein), medium protein (MP; 18% casein), or high protein (HP; 36% casein) in a diet containing a medium fat (corn oil) level. The experimental design permitted distinguishing between the effects of protein levels on initiation and development of various lesions in hamsters, in comparison with a control group that was given MP diet for life. When fed after BOP treatment, HP diet inhibited, among induced tumors, pulmonary adenomas in males. Among spontaneous diseases, LP diet fed before 8 weeks of age enhanced colitis in both males and females, renal and adrenal gland amyloidosis in males, and gastric vascular calcinosis in males but inhibited liver abscesses and liver cysts in both males and females. When fed after 8 weeks of age, LP diet enhanced gastric and renal vascular calcification and parathyroid gland adenomas in both sexes but inhibited hepatic, renal, and adrenal gland amyloidosis in females and liver abscesses and liver cysts in both males and females. The feeding of HP diet before 8 weeks of age enhanced the development of colitis and adrenal gland lipomatosis in both males and females but inhibited the development of adrenal gland amyloidosis and adrenal cortical cell hyperplasia in males. When fed to hamsters after 8 weeks of age, HP diet increased the incidence of adrenal gland amyloidosis in females and colitis in both males and females but reduced the frequency of liver cysts in both males and females and of adrenal cortical cell hyperplasia in males. The overall data and literature review indicate that the effect of dietary protein on tumorigenesis is tissue, sex, species, and strain related.

Modification of pancreatic carcinogenesis in the hamster model. XI. Inhibitory effect of pilocarpine hydrochloride.

Pilocarpine hydrochloride (PH) was administered as a single sc injection (15 mg/kg body wt) to outbred Syrian golden hamsters either prior to, simultaneously with, or after a single 20-mg/kg body weight dose of the pancreatic carcinogen N-nitrosobis(2-oxopropyl)amine (BOP). An additional group was treated with PH, once before and once simultaneously with BOP; another group received PH daily for life after BOP and controls were given BOP only. Surviving hamsters were killed 46 weeks after BOP treatment. PH significantly inhibited pancreatic ductal-ductular cancer induction, whether it was given once before, simultaneously with, or after BOP. A more pronounced inhibitory effect was seen when PH was administered once before and once simultaneously with BOP. However, daily injection of PH did not alter the carcinoma incidence over the BOP control value. The possible mechanisms are discussed.

Enhancement of experimental pancreatic cancer in Syrian golden hamsters by dietary fat.

The effects of dietary fat on the induction and development of pancreatic ductular adenocarcinoma were studied in randombred Syrian golden hamsters. Diets containing low-fat (LF) or high-fat (HF) levels of corn oil [4.5 or 18.0 g/385 kilocalorie (kcal)], contributing 10 or 41% of the calories, respectively, were fed either before or after a single injection of N-nitrosobis(2-oxopropyl)amine (BOP) (10 mg/kg body wt). Control hamsters were fed corn oil at a medium-fat (MD) level (9 g/385 kcal) for life. The incidence of ductular adenocarcinomas increased in both males and females (LF diet, 16%; HF diet, 34%) when the HF diet was fed after BOP treatment. The average number of carcinomas per carcinoma-bearing animal also increased (LF diet, 1.3; HF diet, 3.0), but the carcinoma incidence was not influenced by these diets being fed before carcinogen treatment. The incidence of ductular adenomas was high with all treatments and was not influenced by diet. However, the number of adenomas was increased in animals fed HF diets. In addition, the incidence of acinar cell nodules was elevated in animals fed the MF and HF diets after BOP administration. These results showed that dietary fat modified the development of experimental ductular adenocarcinoma of the pancreas.

Carcinogenicity of diallylnitrosamine following intragastric administration to Syrian hamsters.

Single and multiple intragastric doses of diallylnitrosamine [(DAN) CAS: 16338-97-9] administered to Syrian golden hamsters induced tumors, primarily of the respiratory tract, in which the nasal cavity epithelium was the preferred site. When compared to the effect of DAN after subcutaneous administration at equal doses, the incidence of respiratory tract tumors was lower but that of hepatic tumors was higher, suggesting partial metabolism of DAN in the liver. Comparative metabolic and mutagenesis studies in BD IX rats (which reportedly are refractory to the carcinogenic effects of DAN), in Wistar rats, and in Syrian hamsters showed that a greater proportion of orally administered DAN was exhaled by both rat strains (12-19%) than by hamsters (2-4%). The activity of the microsomal fraction of the hamster liver for metabolizing DAN to allyl alcohol was about 10 times higher than that in rats, whereas no significant species differences were found with the cytosolic fraction. Pretreatment of animals with phenobarbital (PB) or pregnenolone-16 alpha-carbonitrile (PCN) did not influence either microsomal or cytosolic enzyme activities in hamsters, whereas about a tenfold increase in enzyme activities was seen after pretreatment with PB in both rat strains and following PCN in Wistar rats. Moreover, in bacterial mutagenesis assays, hamster liver microsomes were twice as active as those in BD IX rats. The results are discussed in relation to the carcinogenicity of DAN in rats and hamsters.

Modification of pancreatic carcinogenesis in the hamster model. IX. Effect of pancreatitis.

The effect of acute and recurrent pancreatitis was investigated in pancreatic cancer induction by N-nitrosobis(2-oxopropyl)amine (BOP) in Syrian golden hamsters. For the correlation of the cellular alteration with carcinogenesis, BOP (20 mg/kg body wt) was injected once sc into hamsters at day 3 (group 2), week 1 (group 3), and week 8 (group 4), corresponding to cellular degeneration, regeneration, and healing, respectively. Additional groups received BOP 30 minutes before common duct ligation for 48 hours (group 1) or before repeated induction of pancreatitis at 4 weekly intervals for 4 weeks (group 5). Group 6 was a pancreatitis control. Two groups of hamsters received BOP only, at the age of 8 weeks (group 7, which served as a BOP control for groups 1-3 and 5) or at the age of 16 weeks (group 8, the control for group 4). Hamsters were killed 46 weeks after BOP injection (with the exception of group 1 animals, which were killed 52 wk after BOP) to guarantee the same postcarcinogen exposure time in each group. The results showed that BOP, when given during cellular degeneration (group 2) and healing (group 4), induced significantly fewer carcinomas than in the control groups, whereas the tumor pattern was not affected when BOP was given before pancreatitis induction (group 1) or at the time of cellular regeneration (group 3). Recurrent pancreatitis (group 5), however, resulted in carcinomas significantly larger in number and size than those in control group 8. A significantly higher incidence of carcinomas occurred in group 8 controls (treated with BOP at the age of 16 wk) compared to the incidence in group 7 controls (treated with BOP at the age of 8 wk).

Interaction of dietary fat and protein on pancreatic carcinogenesis in Syrian golden hamsters.

The role of interactions between dietary fat and protein in experimental pancreatic cancer was determined in Syrian golden hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). Two levels of corn oil [4.5 and 18 g/385 kilocalorie (kcal)] were fed with each of two levels of casein (9 g/385 kcal and 36 g/385 kcal), either before or after a single sc injection of BOP (10 mg/kg body wt) at 8 weeks of age. Control diet was fed at other times (9 g corn oil and 18 g casein/385 kcal). The pancreatic ductular carcinoma incidence and multiplicity (average No. of tumors/tumor-bearing animals) increased as dietary fat and protein levels rose in hamsters fed the four diets after carcinogen treatment. Enhanced carcinogenesis by high-fat (HF) diets occurred only in hamsters fed the high-protein (HP) level, and protein effects were seen only with the HF diets. The low-fat-low-protein (LF-LP) diet inhibited pancreatic carcinogenesis among the hamsters given the four diets before BOP treatment. Pancreatic adenoma yields were elevated in hamsters given either HF or HP diets following BOP treatment, by comparison with the low levels. However, when diets were fed before BOP treatment, an increased yield occurred with the rise in protein, but the yield was reduced in males with the increase in fat. Acinar cell nodules were observed primarily in hamsters fed LP levels after BOP, and their multiplicity was highest in those given the HF diet. The interaction between dietary fat and protein demonstrated the interdependence of the effects of these two nutrients on pancreatic carcinogenesis in hamsters.

Modification of pancreatic carcinogenesis in the hamster model. XII. Dose-related effect of ethanol.

Ethanol (E) was given to outbred Syrian golden hamsters in drinking water at a 5% (wt/vol) concentration for life beginning either before or after a single dose of N-nitrosobis(2-oxopropyl)amine (BOP). No effects on tumor induction were seen in the pancreas or in other BOP target tissues (e.g., the common duct and gallbladder), whether E was given immediately after or 4 weeks before and immediately after BOP. These results sharply conflicted with our previous findings in which a higher concentration of E (25% wt/vol) inhibited BOP-induced pancreatic lesions, and they indicated a dose-related action of E on pancreatic carcinogenesis. Development of a few acinar cell foci in hamsters treated with BOP and E, but not in those treated with E alone or BOP alone, indicated that E in this concentration alters pancreatic functions without modifying carcinogenesis.

Modifying factors in pancreatic carcinogenesis in the hamster model. I. Effect of protein-free diet fed during the early stages of carcinogenesis.

The role of protein in pancreatic carcinogenesis was examined in outbred Syrian golden hamsters treated with the pancreatic carcinogen N-nitrosobis(2-oxopropyl)amine (BOP) and fed a purified protein-free diet (PPFD). The PPFD was fed for 28 days from 8 weeks of age; before and after animals were fed PPFD, they were given a commercial diet (CD). BOP was given before PPFD feeding (group 1) or at 18 days (group 2) and 28 days (group 3) from the beginning of the PPFD feeding. BOP-treated control hamsters (group 4) were pair-fed a purified control diet (PCD) instead of PPFD. All animals fed PPFD and PCD were returned to a CD for the rest of the experiment, which was terminated in each group 52 weeks after BOP treatment. The results showed a highly significant reduction of tumor incidence (P less than 0.0001) in hamsters that received PPFD, when compared to those fed PCD, regardless of the time of carcinogen administration during the dietary regimen. Hamsters treated with BOP at 18 days of PPFD (group 2) developed neither benign nor malignant pancreatic tumors. The inhibition of pancreatic neoplasms was not related to reduced calorie consumption, since this occurred in the BOP-treated hamsters that were pair-fed the PCD diet. The results indicated that both the initiation and promotion of pancreatic carcinogenesis with BOP in hamsters can be inhibited by lack of protein in the diet given for 4 weeks during the early stages of the neoplastic process.

Transplacental induction of gonadal tumors in rats by a nitrosamine.

Ovarian and testicular tumors were induced in the offspring (F1 generation) of MRC rats that received single or multiple doses of N-nitrosobis(2-oxopropyl)amine on the 14th, 18th, and/or 20th days of pregnancy. The ovarian tumor incidence was significantly higher (46%) in the F1 generation exposed to the carcinogen a single time at the 18th day of gestation, when compared to those exposed at the 14th (P less than 0.005) or 20th days (P less than 0.025), and was highest in those exposed to N-nitrosobis(2-oxopropyl)amine repeatedly (at the 14th through 20th days of gestation). Morphologically ovarian tumors were of a mixed stromal cell-coelomic type. Testicular tumors were of mixed Leydig cell-glandular types and occurred in a higher incidence in the F1 generation exposed to N-nitrosobis(2-oxopropyl)amine at the 14th through 20th day of gestation, compared with those exposed to the carcinogen at other times of the gestation period (P less than 0.0005). This is the first report of transplacental gonadal tumor induction by a nitrosamine.