1998 Fiscal Year Final Research Report Summary
Cancer promotive action of secondary bile acids and preventive effect owing to feeding of diets available for their capture
| Project/Area Number |
09660142
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
食品科学・栄養科学
|
|---|
| Research Institution | Kyoto Prefectural University |
|---|
Principal Investigator |
IIWAMI Kimikazu Kyoto Prefectural University, Professor, 農学部, 教授 (00026569)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SAEKI Tohru Kyoto Prefectural University, Associate Professor, 農学部, 助手 (00275190)
KANAMOTO Ryuhei Kyoto Prefectural University, Associate Professor, 農学部, 助教授 (70147297)
|
|---|
| Project Period (FY) |
1997 – 1998
|
| Keywords | soybean resistant protein / deoxycholic acid / aberrant crypt foci / colonic tumor / bile acid transporter / ileal resection / cancer promotion / cancer prevention |
|---|
| Research Abstract |
Soybean resistant protein comprises about a quarter of the insoluble "high- molecular-weight" fraction (HMF) arising from digestion of soy protein isolate with a microbial protease. Growing F-344 rats undergoing carcinogen treatment were fed HMF- or casein-based diets supplemented with or without deoxycholic acid (DCA), from which several individual colons were excised at 4 weeks' intervals but no tumors were invisible to the naked eye within 12 weeks. On inspection of aberrant crypt foci (ACF), their count in DCA-fed casein group was far less than in other dietary groups. At 39 weeks, 6 rats of the DCA-fed casein group (n=10) and 3 rats of the DCA-fed HMF group (n=9) proved to bear 18 tumors with major axis of 4.0*0.4 mm and 3 tumors with major axis of 2.0*0.1 mm, respectively, in contrast to only a single tumor for the the DCA-unfed casein group (nil for the DCA-unfed HMF group). That is to say, HMF feeding retarded tumor development despite the frequent occurrence of ACF.This effect can be interpreted in terms of the capacity of soybean resistant protein for catching secondary bile acids and carrying out of the colon.
Meanwhile, young-adult rats under resectional operations on ileum and jejunum were treated woth azoxymethane and fed the same DCA-supplemented casein diet as above-mentioned. The colons excised at 39 weeks were inspected for neoplastic lesions. As a result, it turned out that there were significant differences between both groups with ileal or jejunal resection in tumor incidence (Fisher's probability test), ranks of tumor-bearing rats (Mann-Whitney U-test) and site-oriented tumor distribution (Chi-square test for independence). In addition, the unexpected frequency of tumors at proximal colon in the ileum-resected group devoid of Na^+-dependent bile acid transporter implies that lots of DCA must have flowed into the colon and thereby served as a severe rink factor of promoting tumorigenesis.
|
