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Diets containing soy protein isolate (SPI) or genistein (GEN) fed to female rats during pregnancy do not suppress azoxymethane (AOM)‐induced intestinal cancers in the male progeny
Author(s) -
Xiao Rijin,
Frank Julie A,
Skinner Charles M,
Simmen Frank A
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a567-d
Subject(s) - azoxymethane , offspring , soy protein , genistein , biology , pregnancy , casein , colorectal cancer , endocrinology , carcinogenesis , medicine , cancer , physiology , andrology , food science , genetics
Previous studies showed that lifetime dietary SPI inhibits AOM‐induced colon tumorigenesis when compared to casein (CAS)‐containing control diet. The aim of this study was to investigate if cancer protection by dietary SPI or the soy isoflavone GEN is afforded in utero to progeny via dietary exposure of their dams. Pregnant Sprague‐Dawley rats were fed AIN93G diets containing CAS (20%), SPI (20%), or GEN (0.25g/kg) + CAS. After delivery, dams and progeny were switched to CAS diet, except for a subgroup of SPI dams/progeny in which SPI was continued (lifetime SPI). Male offspring were administered AOM at PND 48 and 55. At 19.5 wks post‐AOM, gastrointestinal tumors were evaluated. Relative to CAS‐fed animals, lifetime SPI decreased colon tumor incidence (62.1% vs. 43.4%, P < 0.05). The lifetime‐fed SPI group exhibited a non‐significant decrease in tumor multiplicity when compared to the lifetime CAS group. SPI/CAS and GEN/CAS groups did not differ from lifetime CAS in tumor incidence. However, the SPI/CAS and GEN/CAS groups had increased tumor multiplicity relative to the lifetime SPI diet (2.54, 2.45 vs. 1.59, P < 0.001). All diet paradigms were similar with respect to duodenum tumor incidence and overall intestinal tumor burden. We conclude that dietary SPI or GEN exposure only during pregnancy did not mimic effects of lifetime SPI in conferring protection against colon cancer in rat progeny. Supported by USDA 6251‐51000‐004‐01S.