deoxycholic-acid and Cocarcinogenesis

To elucidate the role of fecal steroids in the malignant tumor formation of colonic epithelial cells, we examined the effects of dietary deoxycholic acid (DCA) and cholesterol (CHL) on fecal steroid concentrations and their impact on colonic crypt cell proliferation. Twenty 5-week-old male Fischer 344 rats were provided with either a control semisynthetic diet or the same diet supplemented with 0.15% DCA and 1% CHL (steroid diet) over a 5-week period. The effects of these two diets were compared among rats that were either injected with azoxymethane (AOM), a known gastrointestinal carcinogen, or saline. In a 2 x 2 factorial design, rats fed each of these diets were given two weekly subcutaneous injections of either AOM (15 mg/kg b.w.) or saline at 6 and 7 weeks of age. At 9 weeks of age, fecal samples were obtained for analysis of bile acids, CHL and its bacterial metabolites of intestinal microflora. At 10 weeks of age, animals were sacrificed and colonic proliferation was assessed as vincristine-accumulated mitotic figures per crypt. Rats fed the steroid diet had significantly elevated fecal bile acid (5x, P < 0.001) and neutral steroid (10x, P < 0.01) levels when compared to those fed the control diet. AOM treatment did not appear to influence these levels. However, rats injected with AOM had a significant increase (P < 0.001) in their rate of colonic cell proliferation as compared to saline-injected control animals on both diets. Furthermore, rats fed the steroid diet had a significantly higher (P < 0.001) cell proliferation rate than animals fed the control diet. The effects of AOM treatment and the steroid diet on cell proliferation were additive. Our results demonstrate that high concentrations of neutral and acid steroids in the colonic lumen can enhance carcinogen-induced elevated cell proliferation and thus may play a key role in the etiology of colon cancer.

Topics: Animals; Azoxymethane; Bile Acids and Salts; Body Weight; Carcinogens; Cell Division; Cholesterol, Dietary; Cocarcinogenesis; Colon; Colonic Neoplasms; Deoxycholic Acid; Eating; Feces; Male; Precancerous Conditions; Rats; Rats, Inbred F344; Steroids

Modifying effects of fibrosis or a cirrhotic state, caused by treatment with swine serum (SS), on the induction of preneoplastic focal lesions were assessed in a rat medium-term liver bioassay model for the detection of environmental carcinogens, in which the test compound is administered during the promotion phase after initiation with diethylnitrosamine. In experiment I, repeated intraperitoneal administration of SS concomitantly with the hepatopromoting agent deoxycholic acid (DCA) or phenobarbital (PB) resulted in a cirrhotic state and a significant increase in the number or size of preneoplastic glutathione S-transferase placental form (GST-P)-positive liver cell foci as compared to the corresponding DCA or PB alone groups. In experiment II, SS was given prior to commencement of the same medium-term bioassay system, in which a known hepatopromoting agent, DCA, 17-alpha-ethynylestradiol, or 2-acetylaminofluorene, was applied. In this case, the liver did not show obvious cirrhotic change and, rather than any enhancement, slight inhibition of promotion occurred. The results indicate that a coexisting, but not a pre-existing, cirrhotic condition acts to increase growth pressure on GST-P+ preneoplastic foci, and suggest that concomitant administration of SS with the promoting agent could be applied to improve the sensitivity of the assay protocol.

Topics: 2-Acetylaminofluorene; Animals; Blood; Chemical and Drug Induced Liver Injury; Cocarcinogenesis; Deoxycholic Acid; Ethinyl Estradiol; Glutathione Transferase; Injections, Intraperitoneal; Liver; Liver Cirrhosis, Experimental; Liver Diseases; Male; Organ Size; Phenobarbital; Precancerous Conditions; Rats; Rats, Inbred F344; Swine

A positive association between deoxcholic acid (DCA) in the serum and colorectal adenomas, the precursors of colorectal cancer has recently been found, which supported the hypothesis of a pathogenic role of DCA in colonic carcinogenesis. This approach was based on the hypothesis that DCA formed in the colon is absorbed into the portal venous blood and exhibits a constant spillover to the systemic circulation. To further substantiate this hypothesis this study investigated whether in the serum of adenoma patients DCA was higher in the unconjugated fraction, which originates directly from the colon. DCA was found to be 2.8-fold higher in the unconjugated fraction of patients with colorectal adenomas than in controls (0.89 v 0.32 mumol/l, p < 0.0025), 1.9-fold in the total DCA fraction (1.89 v 0.95 mumol/l, p < 0.0001), and 1.4-fold in the conjugated fraction (0.67 v 0.47 mumol/l, p < 0.05). It was further found that the bacterial isomerisation product 3 beta-DCA was twofold higher in the unconjugated fraction of adenoma patients than in controls (0.08 v 0.04 mumol/l, p = 0.27), 1.8-fold in the total iso-DCA fraction (0.11 v 0.06 mumol/l, p < 0.05), and 1.5-fold in the conjugated iso-DCA fraction (0.03 v 0.02 mumol/l, p = 0.68). The data suggest that the positive association between the serum DCA concentration and colorectal adenoma as described previously results from the DCA fraction that is absorbed from the colon. This further supports a pathogenic role of DCA in the carcinogenesis of colorectal cancer.

Topics: Adenoma; Bile Acids and Salts; Cocarcinogenesis; Colorectal Neoplasms; Deoxycholic Acid; Humans; Male; Middle Aged

This study was performed to clarify the promoting effects of primary or secondary bile acid load on the occurrence of cholangiocarcinoma, using Syrian golden hamsters. These hamsters received subcutaneously diisopropanolnitrosamine (DIPN) once weekly for 10 weeks, and simultaneously were given a standard pellet diet (control group) containing taurocholic acid (TCA group) or deoxycholic acid (DCA group). The rates of cholangiocarcinoma at 20 weeks were 23% in the control group, 60% in the TCA group and 59% in the DCA group. There were significant differences between the control and the TCA or DCA groups (p < 0.05). The rates of proliferation of bile ductules or hyperplasia of the bile duct epithelium and the bromodeoxyuridine labeling indices of bile duct epithelial cells were high in both groups treated with bile acids, compared with those in the control group. Regarding the composition of bile acids in the intraductal bile, the TCA and DCA groups revealed a decrease in primary bile acids and an increase in DCA. These results suggest that both TCA and DCA given orally promote the occurrence of DIPN-induced cholangiocarcinoma.

Topics: Adenoma, Bile Duct; Animals; Bile Duct Neoplasms; Body Weight; Carcinogens; Cocarcinogenesis; Cricetinae; Deoxycholic Acid; Eating; Liver; Male; Mesocricetus; Mitotic Index; Nitrosamines; Taurocholic Acid

The neoplastic responses of liver to prolonged continuous exposures of deoxycholic acid (DCA) in the diet with or without prior initiation was examined in Fischer 344 (F-344) and Sprague-Dawley (SD) male rats. In both rat strains, 7 months of continuous feeding of 0.5% (F-344 rats) or 1.0% (SD rats) of deoxycholic acid in chow diet generated hepatic nodules which persisted up to 8 months after deoxycholic acid was stopped. In one group of Sprague-Dawley male rats, 7 months of deoxycholic acid was preceded by an initiating dose of diethylnitrosamine. In 10 out of 15 of these rats, not only persistent nodules but also 26 liver cancers (large, multifocal, invasive, lung metastases) become evident by 8 months after cessation of deoxycholic acid.

Topics: Animals; Cocarcinogenesis; Deoxycholic Acid; Diet; Diethylnitrosamine; gamma-Glutamyltransferase; Glutathione Transferase; Liver; Liver Neoplasms; Male; Rats; Rats, Inbred F344; Rats, Inbred Strains

The effects of dietary administration of phenobarbital [(PB) CAS: 50-06-6] or the secondary bile acids, deoxycholic acid [(DCA) CAS: 83-44-3] and lithocholic acid [(LCA) CAS: 434-13-9], on tumorigenesis in the liver, gallbladder, and pancreas were investigated in male Syrian golden hamsters after carcinogenic initiation by N-nitrosobis(2-hydroxypropyl)amine [(BHP) CAS: 53609-64-6]. BHP [500 mg/kg (body wt)] was injected sc once weekly for 5 weeks. The animals were then maintained on a basal diet or a diet containing either 0.05% PB, 0.1% DCA, 0.5% DCA, or 0.5% LCA for 30 weeks. DCA enhanced the development of cholangiocarcinomas without influencing that of hepatocellular lesions. PB promoted the induction of hepatocellular carcinomas but not that of cholangiocarcinomas. LCA was without effect on the induction of either hepatocellular carcinomas or cholangiocarcinomas. DCA at a dose of 0.5% enhanced the induction of polyps in the gallbladder. Both DCA, at a dose of 0.1%, and LCA significantly enhanced the induction of pancreas carcinomas. PB had no effect on the induction of polyps in the gallbladder or of pancreas carcinomas. These data document that different tumors may be differentially promoted following initiation with a common carcinogen.

Topics: Adenoma, Bile Duct; Animals; Bile Acids and Salts; Cocarcinogenesis; Cricetinae; Deoxycholic Acid; Eating; Gallbladder Neoplasms; Lithocholic Acid; Liver Neoplasms, Experimental; Male; Mesocricetus; Nitrosamines; Organ Size; Pancreatic Neoplasms; Phenobarbital; Polyps

Intrarectal exposure of the colon epithelium of the C57BL/6J female mouse to deoxycholic acid [(DCA) CAS: 83-44-3] markedly increased its sensitivity to orally administered 1,2-dimethylhydrazine [(DMH) CAS: 540-73-8]. While 4 mg DMH/kg body weight by itself increased the level of nuclear damage from a background level of 0.2-0.45 aberration per crypt, DMH when combined with DCA at a dose of 150 mg/kg increased the aberrations from 0.2 to 1.75 per crypt. This effect was observed over a wide range of DCA doses (20-300 mg/kg) and was evident when DMH was given up to 10 hours after the DCA. Similar results were observed with DCA in conjunction with benzo[a]pyrene (CAS: 50-32-8) and 2-amino-3,4-dimethylimidazo(4,5-f)quinoline (CAS: 77094-11-2), though in these cases the time at which the peak of nuclear aberrations occurred was somewhat later. No enhancement was seen with DCA and gamma-radiation. These results show that DCA can enhance the nucleotoxic effects of several carcinogens and suggest that DCA can act as a cocarcinogen. The enhancement may be due to the effect of the bile acid on proliferation of the colon epithelial cells or to its effect on the permeability of mucosal cells.

Topics: 1,2-Dimethylhydrazine; Animals; Carcinogens; Cell Nucleus; Cocarcinogenesis; Colon; Colonic Neoplasms; Deoxycholic Acid; Dimethylhydrazines; Dose-Response Relationship, Drug; Female; Mice; Mice, Inbred C57BL; Mitotic Index; Time Factors

The mechanism whereby bile acids promote colon tumor development was studied. Bile acids increase intestinal ornithine decarboxylase (ODC), an effect that is suppressed by indomethacin, an inhibitor of prostaglandin (PG) synthesis. Male Sprague-Dawley rats were pretreated with 0.002% indomethacin solution in drinking water for 3 days, then given a single intrarectal instillation of 20 mg of deoxycholate and/or 1 mg of PGE2. Four hours later, the rats were killed, and the ODC activity was measured in the mucosa of the distal large bowel. ODC was significantly lower in rats given indomethacin plus deoxycholate than in those given deoxycholate alone, but it was significantly higher in rats treated with indomethacin and PGE2 plus deoxycholate. Without deoxycholate, indomethacin plus PGE2 did not elevate ODC compared with indomethacin alone or no treatment. Indomethacin reduced the colonic mucosal PG level. Thus, PGE2 mediates the deoxycholate-induced colonic mucosal ODC activity, and overcomes the inhibition of this enzyme activity by indomethacin. It is concluded that the anti-promoting effect of indomethacin in colon carcinogenesis, previously demonstrated, may result from the indomethacin inhibition of PG synthesis.

Topics: Animals; Cocarcinogenesis; Colon; Colonic Neoplasms; Deoxycholic Acid; Dinoprostone; Enzyme Induction; Indomethacin; Intestinal Mucosa; Male; Ornithine Decarboxylase; Ornithine Decarboxylase Inhibitors; Prostaglandins E; Rats; Rats, Inbred Strains

Bile acids enhance colorectal carcinogenesis in animals and man, perhaps after degradation by faecal anaerobes. The promotional effect of sodium deoxycholate (SDC) and its relationship to bacteria was examined in male Sprague-Dawley rats (n = 115) which had received a 6-week course of azoxymethane (total dose 90 mg kg-1 s.c.) Two groups received 3 X weekly intrarectal (i.r.) instillations of N saline or 0.12 M SDC for 18 weeks. Another group received SDC i.r. plus metronidazole (22.5 mg kg-1) daily in the drinking water. Controls had no instillations or metronidazole alone. By 28 weeks SDC had increased mean colonic crypt depth by 9% (P less than 0.001), and had almost trebled colorectal tumour yields from 2.4 +/- 0.4 per rat (mean +/- s.e.) in controls to 6.4 +/- 0.5 (P less than 0.001). Tumour yields after SDC + metronidazole (4.2 +/- 0.5) remained 75% higher than in controls (P less than 0.01) but were 33% less than after SDC alone (P less than 0.01), and the increase in crypt depth was maintained at 7% (P less than 0.001). Neither metronidazole alone nor saline i.r. had any effect on tumour yield, but metronidazole alone reduced crypt depth by 9% (P less than 0.001). Deoxycholate is a potent cocarcinogen and also stimulates mucosal hyperplasia. Metronidazole reduces its tumour-promoting effect, suggesting that faecal anaerobes are important in bile acid cocarcinogenesis.

Topics: Animals; Azoxymethane; Cocarcinogenesis; Colonic Neoplasms; Deoxycholic Acid; Intestines; Male; Metronidazole; Rats; Rats, Inbred Strains; Rectal Neoplasms

Because the composition of faeces modulates colorectal carcinogenesis, promotional effects of the secondary bile salt sodium deoxycholate (SDC) were compared with those of dilute homogenised faeces (12.5% w/v) or saline alone in rat colon isolated from the faecal stream as a Thiry-Vella fistula (TVF). Each fluid was used to irrigate a group of TVFs 3 times per week for 12 weeks. Other rats had TVF without irrigation or colonic transection and reanastomosis (sham TVF). Operations followed a 6-week course of azoxymethane injections. At sacrifice 15 weeks postoperatively crypt depth and tumour yield were reduced to the same extent in both the non-irrigated TVFs and the SDC-irrigated TVFs, when compared to shams. Irrigation with faeces and saline completely restored crypt depth and partly restored tumour yields to the levels in shams. Tumours were smaller in the SDC group than in the other 4 groups. While tumours developed mainly in the left colon of shams, there was significantly more even distribution in the TVFs. Exclusion of the colon from the faecal stream leads to mucosal hypoplasia and impaired carcinogenesis. Irrigation with faeces or saline partly reverses these changes. Deoxycholate has no such effect and clearly is not co-carcinogenic in this model.

Topics: Animals; Azoxymethane; Body Weight; Cocarcinogenesis; Colonic Neoplasms; Deoxycholic Acid; Feces; Intestinal Neoplasms; Intestines; Male; Rats; Rats, Inbred Strains; Therapeutic Irrigation

It has been suggested that transformation of secondary bile acids into (co)carcinogenic compounds may have a role in the development of cancer of the large bowel. Because of age dependent differences of this disease we undertook a study of cholic and deoxycholic acid metabolism of eleven young adults (group A, 20-30 years old) and eleven elderly persons (group B, 55-75 years old) with a double isotope dilution method. Daily food intake was standardized individually and gut transit time measured with radioopaque pellets and labelled chromium chloride. The 7 alpha-dehydroxylation fractions (the ratio of deoxycholic acid input rate from the large bowel to cholic acid synthesis rate) were higher in group B (P less than 0.01) due to higher deoxycholic acid input rates (P less than 0.005), especially when individuals from both groups with rapid gut transit were compared. As contributory factor was recognized the higher fractional turnover rate of cholic acid in group B. Pool sizes and synthesis rates of cholic acid and gut transit times were similar. In group A, but not in B, gut transit times correlated with deoxycholic acid input rates (P less than 0.01). The differences in bile acid metabolism may be related to a more effective colonic absorption of deoxycholic acid in the elderly persons with a concomitant decrease of active ileal absorption of cholic acid in the elderly persons. Differences in diet or gut transit time between both groups do not seem to be the underlying mechanism.

Topics: Adult; Age Factors; Aged; Bile Acids and Salts; Cholic Acids; Cocarcinogenesis; Colon; Colonic Neoplasms; Deoxycholic Acid; Diet; Female; Humans; Intestinal Absorption; Kinetics; Male; Middle Aged; Risk

Two groups of 20 male Sprague-Dawley rats each were given sc 8 mg azoxymethane/kg body weight and fed a normal diet or one high in beef fat. Control groups were not given azoxymethane. Fat-control animals did not excrete more total bile acids than did the normal-control group but did excrete more deoxycholic acid as the result of increased cholic acid degradation. Azoxymethane itself caused an increase in fecal bile acid concentratation but tended to reduce the level of cholic acid degradation. Fatty acid content in the feces increased in the animals on the fat diet but was not affected by azoxymethane. A fat-diet-dependent increase was apparent in total fecal neutral steroids and a carcinogen-dependent increase in cholesterol degradation. Dietary fat and bile steroids altered by gut microflora were important interrelated factors in the intestinal carcinogenic process of this animal model.

Topics: Animals; Azoxymethane; Bile Acids and Salts; Cholesterol; Cholic Acids; Cocarcinogenesis; Deoxycholic Acid; Dietary Fats; Fatty Acids; Feces; Intestinal Neoplasms; Male; Meat; Neoplasms, Experimental; Rats