Inhibitory effect of 1alpha-hydroxyvitamin D3 on N-methyl-N'-nitro-N-nitrosoguanidine-induced gastrointestinal carcinogenesis in Wistar rats.

The effect of 1alpha-hydroxyvitamin D3 (1alpha(OH)D3) on gastrointestinal carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in male Wistar rats. After oral treatment with 0.01% MNNG for 24 weeks, rats were given 0.04 microg of 1alpha(OH)D3 or its vehicle by gastric intubation three times a week for 24 weeks. The incidence of gastrointestinal tumors was 16/30 (53%) in rats treated with MNNG alone, 16/30 (53%) in those treated with MNNG plus vehicle and 8/30 (27%, P < 0.05) in those treated with MNNG plus 1alpha(OH)D3. The number of tumors per rat in the group treated with MNNG plus 1alpha(OH)D3 was half those in the control groups (P < 0.05). Results indicated that a non-hypercalcemic dose of 1alpha(OH)D3 had an inhibitory effect on MNNG-induced duodeno-intestinal carcinogenesis.

[Helicobacter pylori and gastric cancer].

H. pylori has been included as a definite biological carcinogen by WHO/ IARC. H. pylori is thought to play a role in the gastritis-metaplasia-carcinoma sequence by inducing atrophic gastritis. Clinical and epidemiological studies have shown a close association between H. pylori infection and gastric cancer. Yet, experimental evidence is equivocal. Epidemiological evidence also suggests that there are significant variable(s) other than H. pylori infection in gastric carcinogenesis. Clearly many questions regarding the role of H. pylori in gastric carcinogenesis have been left for further study. The authors have summarized these aspects together with their experimental results.

Sulphated bile acid per se inhibits colonic carcinogenesis in mice.

Peroral sulpholithocholic acid (SLC) promoted colonic tumorigenesis in conventional rats. We then tested this compound in the mouse, a species with different bile acid metabolism from the rat. Female conventional ICR mice received 0.5 mg of N-methyl-N-nitrosourea (MNU) three times in one week intrarectally or 16 mg/kg body weight of 1,2-dimethylhydrazine (DMH) subcutaneously once a week for 10 weeks, followed by a basal diet (CE-2), or CE-2 containing SLC or lithocholic acid (LC) (both at 0.5 mmol/100 g CE-2) for 40 weeks. At autopsy, numbers of mice bearing colonic neoplasms were 4/26 (15%) in the MNU + CE-2, 4/23 (17%) in the MNU + SLC, 5/28 (18%) in the MNU + LC, 12/24 (50%) in the DMH + CE-2, 6/23 (26%) in the DMH + SLC and 11/27 (41%) in the DMH + LC group. The DMH + SLC group had less adenocarcinomas than did the DMH + CE-2 and the DMH + LC group (P < 0.05). Total faecal bile acids in the mice fed on bile salts showed threefold increases compared with those on the basal diet. Sulphates constituted an average 7% and 19% of faecal bile acids in the MNU + SLC and DMH + SLC group, respectively. These results indicated that effects of peroral SLC on colonic carcinogenesis correlated with the degree of desulphation of SLC in the intestine and sulphates per se inhibited colonic carcinogenesis.

Helicobacter pylori is not a co-carcinogen in N-methyl-N'-nitro-N-nitrosoguanidine-induced rat gastric carcinogenesis.

Helicobacter pylori was implicated in gastric carcinogenesis through the induction of metaplasia of the gastric mucosa. In this experiment a co-carcinogenic effect of H. pylori on chemically induced gastric carcinogenesis was examined. Wistar WKY male rats received drinking water containing 50 mg/l of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and intragastric administration of 10(6) to 10(8) colony forming unit of H. pylori thrice a week for 40 weeks. Thus, 3 groups were assigned as Group I; MNNG alone, Group II; MNNG + vehicle, and Group III; MNNG + H. pylori (n = 30, each). At autopsy, 9 rats (30%) had 7 glandular stomach and 3 duodenal tumors in Group I, and 10 rats (33%) had 8 glandular stomach and 2 duodenal tumors in Group II, whereas in Group III 4 rats (13%) had 2 glandular stomach and 2 duodenal tumors (chi 2 = 4.257, P < 0.15 for the incidences of glandular stomach tumors among 3 groups). The finding seems to suggest that H. pylori has an ambitendency in the gastritis-metaplasia-carcinogenesis sequence as a promoter for the induction of the predisposing mucosa and as an inhibitor against certain carcinogens.

Suppressive effect of wasabi (pungent Japanese spice) on gastric carcinogenesis induced by MNNG in rats.

Dietary habits have been causally implicated in gastric carcinogenesis, whereas minor dietary items may also play a part. Wasabi is a popular pungent spice in Japanese meals. In this study the effect of wasabi on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis was studied in rats. Wistar WKY male rats received drinking water containing 50 micrograms/ml of MNNG or tap water alone and a basal diet (PCE-2) or PCE-2 containing 10% (wt/wt) of wasabi powder for 40 weeks. Thus, three groups were completed as MNNG + PCE-2 (n = 30), MNNG + wasabi (n = 30), and tap water + wasabi (n = 30). At autopsy, nine rats (30%) had seven glandular stomach tumors (2 adenocarcinomas, 2 adenomatous polyps, and 3 adenomatous glandular hyperplasias) and three duodenal adenocarcinomas in the MNNG + PCE-2 group, whereas in the MNNG + wasabi group, two rats (7%) had one forestomach epidermoid cyst and one duodenal carcinosarcoma (corrected chi 2 = 4.63, p less than 0.05 for incidences of glandular stomach tumors between 2 groups). In addition, two rats had microscopic atypical glands in the MNNG + PCE-2 group. There was no tumor in the tap water + wasabi group. These results indicated that glandular stomach carcinogenesis induced by MNNG was suppressed by the administration of wasabi.

1 Alpha-hydroxyvitamin D3 suppresses colonic tumorigenesis induced by repetitive intrarectal injection of N-methyl-N-nitrosourea in rats.

The effect of 1 alpha-hydroxyvitamin D3 (1 alpha (OH)D3) on colonic tumorigenesis induced by chronic treatment with N-methyl-N-nitrosourea (MNU) was studied in rats. Seventy-four female F344 rats received an intrarectal injection of 1 mg of MNU once a week for 40 weeks. Two-thirds of rats were given concomitant administration of 0.2 ml of medium chain triglyceride (MCT) or MCT containing 0.04 microgram of 1 alpha (OH)D3 through an intragastric route thrice weekly. Numbers of rats bearing colonic tumor were 21 in MNU alone (n = 24), 17 in MNU + MCT (n = 25) and 12 in MNU + 1 alpha (OH)D3 group (n = 25) (uncorrected chi 2 = 8.72). The result indicated that colonic tumorigenesis induced by the chronic treatment with MNU was suppressed by oral supplementation of 1 alpha (OH)D3 and the inhibitory effect of 1 alpha (OH)D3 was partly due to the effect of MCT.

Effects of 1 alpha-hydroxyvitamin D3 on N-methyl-N-nitrosourea-induced colonic tumorigenesis, and on fecal bile acid profiles with respect to soluble and precipitated phases in rats.

Vitamin D3 inhibited the promotion by exogenous promoters in experimental colonic tumorigenesis. To give more insight into this phenomenon, the effect of 1 alpha-hydroxyvitamin D3 (1 alpha(OH)D3) on N-methyl-N-nitrosourea (MNU)-induced colonic tumorigenesis was studied in rats without exogenous promoters. Fecal bile acids were analyzed to examine as to whether 1 alpha(OH)D3 increased the concentration of soluble bile acids. Eighty-seven female F344 rats received 2 mg of MNU intrarectally 5 times in 2 weeks, and were divided into 3 groups. One group (n = 29) was left without any treatment. Two groups (each, n = 29) were given 0.2 ml of medium chain triglyceride (MCT) or MCT containing 0.04 microgram of 1 alpha(OH)D3 through an intragastric route thrice weekly for 38 weeks. At autopsy, numbers of rats with colonic tumor were 9 (31%), 10 (34%) and 10 (34%) in the group receiving MNU alone, MNU + MCT and MNU + 1 alpha(OH)D3, respectively (chi 2 = 0.103, P less than 0.95). Fecal bile acid profiles showed no appreciable difference among these groups, nor was observed any increase of soluble bile acids in the MNU + 1 alpha(OH)D3 group. These results indicated that the administration of 1 alpha(OH)D3 did not affect colonic tumorigenesis under the condition where exogenous promoters were not applied, and that 1 alpha(OH)D3 did not seem to interfere the formation of bile acid calcium salts in animals on a regular diet.

Difference in enzymatic sulfation of bile acids between the mouse and rat.

Species difference in bile acid-sulfotransferase (BAST) activity was studied between the mouse and rat. Cytosol fractions of the liver, kidney, small intestine and large intestine were incubated with bile acids and 3' phosphoadenosine-5'-phosphosulfate. The mouse liver showed BAST activity for lithocholic acid, taurolithocholic acid and taurochenodeoxycholic acid, whereas the rat liver and kidney had the activity for taurodeoxycholic acid in addition to these compounds. The highest activities were found in the mouse liver and rat kidney. The mouse small intestine showed weak activity only for lithocholic acid. No activity was found in other organs. BAST was inactive towards taurocholic acid, 7 alpha- or 12-monohydroxy-5 beta-cholanoic acid. Optimal pH of liver BAST in the two species was different from that of the rat kidney. BAST of the mouse liver showed the highest activity without addition of Mg2+, whereas that of the rat liver and kidney showed enhancement by exogenous Mg2+. These results indicated that the distribution and characteristics of mouse BAST was different from rat BAST. Such difference should be reminded in any animal study involving the two species.

Supplemental administration of 1 alpha-hydroxyvitamin D3 inhibits promotion by intrarectal instillation of lithocholic acid in N-methyl-N-nitrosourea-induced colonic tumorigenesis in rats.

The effect of 1 alpha-hydroxyvitamin D3 [1 alpha(OH)D3] on promotion by intrarectal instillation of lithocholic acid (LC) in N-methyl-N-nitrosourea (MNU)-induced colonic tumorigenesis was studied in a rodent model. Ninety-two female F344 rats received intrarectal injection of 2.5 mg of MNU twice in one week followed by 1 mg of LC or its vehicle alone three times weekly for 48 weeks. Those which received LC were given a concomitant intragastric administration of 0.04 micrograms of 1 alpha(OH)D3 or its vehicle alone three times weekly. In the group receiving MNU alone (n = 30) five rats bore colonic tumors; in the MNU + LC group (n = 32) 15 and in the MNU + LC + 1 alpha(OH)D3 group (n = 30) six rats bore colonic tumors (MNU + LC versus MNU + LC + 1 alpha(OH)D3 group, P less than 0.05). These results indicated that promotion of MNU-induced colonic tumorigenesis by LC was suppressed by supplemental administration of 1 alpha(OH)D3.

Effects of oral administration of sulfolithocholic acid disodium salt and lithocholic acid sodium salt on N-methyl-N-nitrosourea-induced colonic tumorigenesis in conventional rats.

Effects of p.o. administration of sulfolithocholic acid disodium salt (SLCNa) and lithocholic acid sodium salt (LCNa) on N-methyl-N-nitrosourea (MNU)-induced colonic tumorigenesis were studied in conventional rats. Female F344 rats received either 0.5 ml of distilled water (DW) alone or DW containing 2.5 mg of MNU twice in 1 wk intrarectally. Then rats were fed freely on a basal diet (PCE-2) or PCE-2 containing LCNa or SLCNa (both at 0.5 mmol/100 g of PCE-2) for 40 wk. Thus, 6 groups were completed: MNU + PCE-2 (n = 30); MNU + LCNa (n = 29); MNU + SLCNa (n = 22); DW + PCE-2 (n = 17); DW + LCNa (n = 20); and DW + SLCNa (n = 19). Numbers of rats bearing colonic tumor were 3 (10%) in MNU + PCE-2, 2 (7%) in MNU + LCNa, and 8 (36%) in MNU + SLCNa group (uncorrected x2 = 9.35 among the 3 groups), but none in those groups without MNU. Total fecal bile acids in the rats given bile salts showed about 2-fold increase compared with those without bile salts. Fecal bile acid profiles between the LCNa and SLCNa groups were indistinguishable except for a slight increase of sulfolithocholic acid in the SLCNa groups. These results indicated that p.o. administration of SLCNa but not LCNa promoted MNU-induced colonic tumorigenesis in conventional rats. Fecal bile acid profiles did not support the higher tumor incidence in the MNU + SLCNa group compared with the MNU + LCNa group, which suggested that an unrecognized mechanism probably relating to desulfation of SLCNa was involved in this phenomenon.

Promoting effect of 5 beta-chol-3-en-24-oic acid on N-methyl-N-nitrosourea-induced colonic tumorigenesis in rats.

The effect of 5 beta-chol-3-en-24-oic acid (delta 3) on N-methyl-N-nitrosourea (MNU)-induced colonic tumorigenesis was studied by intrarectal injection of these compounds in rats. Female Fischer rats received 0.5 ml of distilled water (DW) alone or DW containing 2.5 mg of MNU twice in one week followed by 0.5 ml of peanut oil (PO) alone or PO containing 1 mg of delta 3, or 1 mg of lithocholic acid (LC) thrice weekly for 48 weeks. Thus, 6 groups were employed as follows: group I, DW + PO (n = 12); group II, DW + delta 3 (n = 30); group III, DW + LC (n = 30); group IV, MNU + PO (n = 30); group V, MNU + delta 3 (n = 30) and group VI, MNU + LC (n = 37). Fecal bile acid profiles were analyzed before and during the treatment. Numbers of rats bearing colonic tumor were none in the groups without MNU, but 5 (17%) in group IV, 15 (50%) in group V and 12 (32%) in group VI (corrected X2 = 6.07, P less than 0.025 for group IV vs V, and 1.42, P less than 0.3 for group IV vs VI). Total numbers of tumors were 7, 17 and 15 in group IV, V and VI, respectively, and they were mostly adenomas and adenocarcinomas. A breast fibroadenoma in one rat of group VI was the sole extracolonic neoplasm in these rats. Total fecal bile acids ranged from 7.7 to 10.5 mumol/g dry feces during the study without any significant quantitative or qualitative difference with respect to with or without bile acids and MNU treatment. These results indicated that delta 3 promoted MNU-induced colonic tumorigenesis in rats without alteration in bile acid metabolism.

Granular cell tumor of the ascending colon: a case report.

A granular cell tumor (granular cell myoblastoma) of the ascending colon in a 48-year old male is reported. The tumor was detected by barium enema study as a sessile polyp, and colonofiberscopy revealed submucosal tumor. It was removed by endoscopic polypectomy. Macroscopic examination showed the characteristic features of granular cell tumor. The avidin-biotin-peroxidase complex (ABC) method for detection of S-100 protein demonstrated that the cytoplasm of tumor cells and the pleomorphic nuclei were strongly stained with anti-S-100 protein serum, which supports the concept of the Schwann cell origin of granular cell tumor.

High concentration and retained amidation of fecal bile acids in patients with active ulcerative colitis.

Fecal bile acid profiles of 14 patients with ulcerative colitis in the active phase were analyzed to study the potential significance of bile acids in the pathophysiology of this disease, and the results were compared with those in 12 healthy controls. The excretion levels of total bile acids (mean +/- SD) in patients were higher than in controls, 445.1 +/- 392.1 vs 215.5 +/- 148.0 mumol/day, 3.1 +/- 1.7 vs 1.6 +/- 1.0 mumol/g wet feces (P less than 0.05), and 17.2 +/- 9.2 vs 12.4 +/- 13.3 mumol/g dry feces. Fecal profiles of individual bile acids showed higher levels of primary bile acids (52 +/- 27%) in patients compared to those (26 +/- 21%) in controls. Proportions of glycine and taurine conjugates in patients (26 +/- 24%) were higher than in controls (5 +/- 2%) (P less than 0.05), whereas proportions of unconjugates and sulfates were lower in patients than in controls. Accordingly the extent of deconjugation and dehydroxylation of bile acids was lower in patients than in controls. These trends were prominent in patients with more severe disease activity. A high concentration of bile acids in the intestine may have a significant role in the pathophysiology of ulcerative colitis at active phase.

Carcinogenicity of dipyrone in (C57BL/6 X C3H)F1 mice.

The carcinogenicity of dipyrone (sulpyrin)--[(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4 -yl) methylamino]methanesulfonic acid sodium salt monohydrate--which is widely used as an antipyretic anodyne in Japan and in some European countries, was examined in 314 (C57BL/6 X C3H)F1 mice. Male animals were given 0.5% (group I-a) or 0.125% (group I-b) dipyrone in their drinking water for 78 weeks, and female animals were given 1.0% (group II-a) or 0.25% (group II-b) dipyrone in their drinking water for 78 weeks; both males and females were observed for 86 weeks. Twenty-seven of 48 (56%) group I-a animals and 36 of 44 (82%) group II-a animals developed hepatic tumors, and the tumors in group II-a mice developed earlier than those in the control animals. The tumor incidences were significantly higher than those of 8 of 44 (18%) and 3 of 51 (6%) in the respective control groups. The multiplicity of the hepatic tumors was also significantly increased in groups I-a, I-b, and II-a. Hepatic adenoma incidence was related to the dose of dipyrone in the males. These results show that dipyrone enhances the development of hepatic tumors in mice.

Perianal lesions of BALB/c mice induced by 1,2-dimethylhydrazine dihydrochloride and methylazoxymethanol-acetate: their classification and histogenesis.

The histogenesis of perianal squamous cell carcinomas induced by subcutaneous and intraperitoneal injection of 1,2-dimethylhydrazine dihydrochloride (DMH) and painting of methylazoxymethanol (MAM)-acetate on the anal region was investigated in 212 female BALB/c mice. Painting of MAM-acetate and injection of DMH induced similar benign and malignant tumors and hyperplastic lesions in the anal region. In chronological studies on animals given DMH subcutaneously, cystic or solid squamous lesions, foci of immature sebocytes, sebaceous hyperplasias and sebaceous adenomas were identified. These lesions seemed to be precursors of carcinomas that developed in the same region, and originated from hair follicles or sebaceous glands of the pilosebaceous complexes, but not from the anal mucosa. In mice treated with DMH, the incidence of perianal carcinomas was high in groups with high incidences of colon carcinomas.