The activities of several detoxication enzymes are differentially induced by juices of garden cress, water cress and mustard in human HepG2 cells.

It has been previously demonstrated in a human-derived hepatoma cell line (HepG2) that juices from cruciferous vegetables protect against the genotoxicity caused by dietary carcinogens. HepG2 cells possess different enzymes involved in the biotransformation of xenobiotics. Therefore, we investigated the effect of cruciferous juices on the activities of CYP 1A and several phase II enzymes in this cell model. For each experiment, 1 x 10(6) cells were seeded on Petri dishes. After 2 days, the juices (0.5-8 microl/ml of culture medium) were added for 48 h prior to cell harvesting. The addition of juice from water cress (Nasturtium officinalis R. Br) significantly increased the activities of ethoxyresorufin-O-deethylase at high doses only and NAD(P)H-quinone reductase in a dose-dependent manner (1.8- and 5-fold, respectively). The addition of juice from garden cress (Lepidum sativum L.) significantly increased the activities of NAD(P)H-quinone reductase and UDP-glucuronosyl-transferase with a maximal effect around the dose of 2 microl/ml juice (1.4- and 1.2-fold, respectively) while the other enzymes were not altered. Mustard (Sinapis alba L.) juice increased the activities of NAD(P)H-quinone reductase (2.6-fold at the dose of 8 microl/ml), and N-acetyl-transferase (1.4-fold at the dose of 8 microl/ml) in a dose-dependent manner while a maximal induction of UDP-glucuronosyl-transferase was obtained with a dose of 2 microl/ml (1.8-fold). These observations show that the three juices have different induction profiles: only water cress acted as a bifunctional inducer by enhancing both phase I and phase II enzymes. As a consequence, each juice may preferentially inhibit the genotoxicity of specific compounds.

Effect of intestinal microfloras from vegetarians and meat eaters on the genotoxicity of 2-amino-3-methylimidazo[4,5-f]quinoline, a carcinogenic heterocyclic amine.

Aim of this study was to investigate the impact of intestinal microfloras from vegetarians and non-vegetarians on the DNA-damaging activity of 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ), a carcinogenic heterocyclic amine that is found in fried meats. Floras from four vegetarians (Seventh Day Adventists) and from four individuals who consumed high amounts of meats were collected and inoculated into germfree F344 rats. The rats were kept on isocaloric diets that either contained animal derived protein and fat (meat consumers group) or proteins and fat of plant origin (vegetarian groups). IQ (90 mg/kg bw) was administered orally, after 4 h the extent of DNA-damage in colon and liver cells was determined in single cell gel electrophoresis assays. In all groups, the IQ induced DNA-migration was in the liver substantially higher than in the colon. In animals harbouring floras of vegetarians, the extent of damage was in both organs significantly (69.2% in the liver, P<0.016 and 64.7%, P<0.042 in the colon, respectively) lower than in the meat consumer groups. Our findings show that diet related differences in the microfloras have a strong impact on the genotoxic effects of IQ and suggest that heterocyclic amines are less genotoxic and carcinogenic in individuals that consume mainly plant derived foods.

The human colonic microflora influences the alterations of xenobiotic-metabolizing enzymes by catechins in male F344 rats.

As other xenobiotics, polyphenols are metabolized both by the endogenous detoxication system and the gut microflora. We hypothesized that the presence of a gut microflora may account for the effect of catechins on phase I and II xenobiotic-metabolizing enzymes and that the human bacterial metabolites may be different from those of a rodent gut microflora. Therefore, the effects of 2% (+)-catechin or 2% (-)-epicatechin were studied in germ free (GF) rats and rats inoculated with the flora of a human volunteer (HFA). In addition, the catechins were administered in ethanol as a vehicle. In the liver, (+)-catechin or (-)-epicatechin decreased the total amount of CYP450 in both GF and HFA rats while the isoenzyme CYP2E1 decreased. In GF rats only, CYP2C11 increased when compared to the rats treated with the vehicle alone. (+)-catechin increased the specific activity of UGT-chloramphenicol in GF rats only and that of cytosolic glutathion-S-transferase (GST) in HFA rats only. In the intestine, (+)-catechin and (-)-epicatechin increased the specific activity of UGT-4-methylumbelliferone in both GF and HFA rats and that of UGT- chloramphenicol in HFA rats only. In conclusion, the presence of a human flora in rats is able to modify the inducing effect of catechins on the UGT and GST activities suggesting the involvement of bacterial metabolites. The alterations on CYP 450 are independent of the presence of a human gut flora.

Early adaptation of pancreas to a protein-enriched diet: role of cholecystokinin and gastrin-releasing peptide.

Feeding rats a diet containing high levels of protein (as casein) increases the secretion and biosynthesis of pancreatic serine proteases. Cholecystokinin (CCK) presumably plays a role in this process although other GI peptides such as the gastrin-releasing peptide (GRP) may be involved. In this article, we describe the kinetics of pancreatic adaptation to a diet containing 45% protein as soybean and fish. Then we report the effect of treatment with either a cholecystokinin-receptor antagonist (MK-329) or a gastrin-releasing peptide-receptor antagonist ([D-F5 Phe6, D-Ala11]-Bn(6-13)OMe, or BIM 26226) on pancreatic adaptation to this diet. Prior to experiments, adult male Fischer rats received a diet containing 22% protein for 1 week. In the first experiment, 48 rats were fed a diet containing 45% protein; they were killed after 0-7 days. In the second experiment, 53 rats were fed the 22- or 45%-protein diet and received three daily injections of either the vehicle alone, MK-329, or BIM 26226 for 7 days before they were killed. When the protein-rich diet was fed for 0-7 days, amylase, in vitro biosynthesis, and mRNA levels were gradually decreased while serine protease biosynthesis was increased, reflecting the general enhancement of chymotrypsinogen, trypsinogen, and elastase mRNA levels. For all these parameters, adaptation leveled off after a 5-day feeding. When the protein diets were fed for 7 days, MK-329 significantly inhibited the adaptation of trypsin (specific activity and mRNA) and elastase (mRNAs) to the 45%-protein diet. BIM 26226 had no effect on pancreatic adaptation to the protein-rich diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of the growth of azaserine-induced nodules in the rat pancreas by dietary camostate (FOY-305).

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.

Effect of bombesin and caerulein on early stages of carcinogenesis induced by azaserine in the rat pancreas.

This study was designed to analyze the effect of two pancreaticotrophic peptides on pancreatic carcinogenesis in the azaserine-rat model. The rats were treated with bombesin or caerulein for 16 weeks after initiation with azaserine. Two-week-old Lewis rats were given injections of a single dose of azaserine (30 mg/kg) and the control pups received an injection of saline. They were divided into ten groups for peptide treatment as follows: Group 1, azaserine-saline; Group 2, azaserine-bombesin, 10 micrograms/kg; Group 3, azaserine-bombesin, 30 micrograms/kg; Group 4, azaserine-caerulein, 5 micrograms/kg; Group 5, azaserine-caerulein, 15 micrograms/kg; Group 6, control-saline; Group 7, control-bombesin, 10 micrograms/kg; Group 8, control-bombesin, 30 micrograms/kg; Group 9, control-caerulein, 5 micrograms/kg; and Group 10, control-caerulein, 15 micrograms/kg. At 3 weeks of age, they were weaned. Peptides or saline were injected 3 consecutive days a week for 16 weeks. Rats were autopsied 4 months after the administration of azaserine. Pancreatic weight was increased by bombesin and decreased by caerulein treatment. Quantitative histological analysis of azaserine-induced atypical acinar cell nodules in the pancreas showed that the size and number of atypical acinar cell nodules were increased in both bombesin- and caerulein-treated groups. Thus, these peptides appear to stimulate the growth of preneoplastic acinar cell lesions.

Effect of castration and hormone replacement on azaserine-induced pancreatic carcinogenesis in male and female Fischer rats.

Previous reports have shown that pancreatic cancer was induced preferentially in male versus female azaserine-treated rats. This study was designed to determine the importance of estrogen and testosterone in this phenomenon. Fischer (F344) rats received a single injection of azaserine (30 mg/kg) at 21 days of age. At 28 days of age, they were weaned and divided into 12 groups of 9-10 rats as shown below. Surgery (castration or sham operation) was performed at 4 weeks of age. All drugs (estradiol, the antiestrogen tamoxifen, testosterone propionate and/or the antiandrogen flutamide) were administered, starting at weaning, in 3-week timed-release pellets until autopsy. Rats were killed 4 months after the administration of azaserine. The pancreas was weighed and prepared for quantitative histologic analysis of atypical acinar cell nodules (AACNs) which are putative preneoplastic lesions. Both number and size of AACNs were analyzed. In intact female rats, AACN burden was smaller than in intact males (P less than 0.05). Ovariectomy increased the AACN burden (P less than 0.05), while estradiol or tamoxifen treatments to ovariectomized females resorted the burden to control levels (P less than 0.05). Testosterone with tamoxifen treatment to ovariectomized females led to a significant increase in AACN burden over control values. In intact male rats, orchiectomy decreased the AACN burden (P less than 0.05). In orchiectomized rats, testosterone treatment slightly increased the AACN burden, flutamide treatment alone increased this parameter (P less than 0.05) but flutamide with estradiol decreased the AACN burden (P less than 0.01). These data strongly support the hypothesis that sex steroids play a major role in the higher incidence of pancreatic cancer in male versus female rats.

Effect of orchiectomy and testosterone on the early stages of azaserine-induced pancreatic carcinogenesis in the rat.

The incidence of carcinoma of the pancreas is higher among men than women. It is also higher among male than female carcinogen-treated rats. The role of testosterone in this preferential induction of pancreatic cancer was evaluated in a rat model of pancreatic carcinogenesis. Two-week-old Lewis rats were treated with a single injection of azaserine. At weaning (3 weeks), rats were divided into five groups as follows: females; intact males; sham-operated males; orchiectomized males; and orchiectomized males plus testosterone. Four months after administration of azaserine, quantitative histologic analysis of atypical acinar cell foci and nodules of the pancreas showed that in female and orchiectomized male rats, foci and nodules were smaller and less numerous than in intact males. Testosterone treatment partly reversed the effect of orchiectomy. This suggests that the susceptibility of male rats to induction of pancreatic carcinomas by azaserine is at least partially mediated by testosterone. Estrogen and testosterone receptors were assayed, but high-affinity receptors characteristic of gonadal tissues were not detected in normal pancreas or in a transplantable azaserine-induced acinar cell carcinoma. Thus, the effect of testosterone in the pancreas may depend on steroid-binding proteins of another type, or may be indirectly mediated.