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Genistein protects female nonobese diabetic mice from developing type 1 diabetes when fed a soy- and alfalfa-free diet.

ABSTRACT: The objective of this study was to determine the effects of the phytoestrogen genistein (GEN) on the time of onset and/or the incidence of type 1 diabetes (T1D) in female nonobese diabetic (NOD) mice, when administered GEN by gavage once every day for up to 180 days. Five groups of mice (approximately 24 animals/group; 6-7 weeks of age) were included: naive control, vehicle control (25 mM Na2CO3 in water), and 3 GEN treatment groups (2 mg/kg, 6 mg/kg, and 20 mg/kg). Mice were maintained on a soy- and alfalfa-free diet (5K96) during the study and were monitored for blood glucose changes every week. When compared to the vehicle control, exposure to 2-mg/kg GEN produced significant decreases ranging from 55 to 79% in the total incidences of diabetes (blood glucose ? 250 mg/dl) and severe diabetes (blood glucose ? 400 mg/dl) starting at week 14 of the study. However, during the later stages of the study (i.e., after week 23), the 2-mg/kg dose had no effect on disease incidence. In animals treated with 6-mg/kg and 20-mg/kg GEN, significant decreases in the total incidence of diabetes were observed starting at week 16, while the incidence of severe diabetes was significantly decreased with the changes being observed initially at weeks 18 and 17 for the 6-mg/kg and 20-mg/kg GEN treatment groups, respectively. Several lines of evidence, including histopathological analysis, suggested that GEN protected the pancreas from autoimmune destruction. However, this protective effect of GEN was absent when female NOD mice were maintained on NTP-2000 rodent diet, which contained 5% soybean meal and 7.5% alfalfa meal (the total concentrations of phytoestrogens ranged between 95 and 134 mg/kg). In summary, oral dosing of GEN reduced the incidence and increased the time to onset of T1D in female NOD mice but only when fed a soy- and alfalfa-free diet.

SUBMITTER: Guo TL

PROVIDER: S-EPMC4190109 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Genistein protects female nonobese diabetic mice from developing type 1 diabetes when fed a soy- and alfalfa-free diet.

Guo Tai L TL Germolec Dori R DR Zheng Jian Feng JF Kooistra Linda L Auttachoat Wimolnut W Smith Matthew J MJ White Kimber L KL Elmore Susan A SA

Toxicologic pathology 20140408 3

The objective of this study was to determine the effects of the phytoestrogen genistein (GEN) on the time of onset and/or the incidence of type 1 diabetes (T1D) in female nonobese diabetic (NOD) mice, when administered GEN by gavage once every day for up to 180 days. Five groups of mice (approximately 24 animals/group; 6-7 weeks of age) were included: naive control, vehicle control (25 mM Na2CO3 in water), and 3 GEN treatment groups (2 mg/kg, 6 mg/kg, and 20 mg/kg). Mice were maintained on a soy ...[more]

PMID: 24713318

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Project description:The role of diet in the prevention of breast cancer is widely accepted, yet little is known on how early dietary effects mitigate adult cancer risk. Soy consumption is associated with reduced breast cancer risk in women, an effect largely attributed to the soy isoflavone genistein (GEN). We previously showed lower chemically-induced mammary tumor incidence in young adult rats with lifetime dietary intake of soy protein isolate (SPI), a highly refined soy product in infant formula, than in those fed the control diet Casein (CAS). To gain insight into signaling pathways underlying dietary tumor protection, we performed genome-wide expression profiling of mammary epithelial cells from young adult rats lifetime fed CAS, SPI, or supplemental GEN-based diets. We identified mammary epithelial genes regulated by SPI (79 total) and GEN (99 total) using Affymetrix rat 230A GeneChip arrays and found minimal overlap in gene expression patterns. We showed that the regulated transcripts functionally cluster in biochemical pathways involving metabolism, immune response, signal transduction, and ion transport. We confirmed the differential expression of Wnt (Wnt5a, Sfrp2) and Notch (Notch2, Hes1) signaling components by SPI and/or GEN using QPCR. Wnt pathway inhibition by GEN was supported by lower Cyclin D1 immunoreactivity in mammary ductal epithelium of GEN relative to CAS and SPI, despite their comparable levels of membrane-localized E-cadherin and Î²-catenin. Identification of distinct GEN and SPI responsive genes in mammary epithelial cells may define early events contributing to tumor protection by diet relevant to the prevention of breast and other types of cancer. Experiment Overall Design: Female Sprague-Dawley rats, fed one of the three purified diets, were studied at postnatal day50. Total RNA( each RNA samples were extracted from #4 mammary gland from two animals under the same diet group) purified from non-tumor tissue within the proximal half of each colon, was used to prepare biotinylated probes, which were hybridized to Affymetrix RAE230 rat microarrays.

Project description:Alcoholic and nonalcoholic fatty liver diseases are risk factors for development of hepatocellular carcinoma, but the underlying mechanisms are poorly understood. On the other hand, ingestion of soy-containing diets may oppose the development of certain cancers. We previously reported that replacing casein with a soy protein isolate reduced tumor promotion in the livers of mice with alcoholic liver disease after feeding a high fat ethanol liquid diet following initiation with diethylnitrosamine. Feeding soy protein isolate inhibited processes that may contribute to tumor promotion including inflammation, sphingolipid signaling, and Wnt/?-catenin signaling. We have extended these studies to characterize liver tumor promotion in a model of nonalcoholic fatty liver disease produced by chronic feeding of high-fat liquid diets in the absence of ethanol. Mice treated with diethylnitrosamine on postnatal day 14 were fed a high-fat liquid diet made with casein or SPI as the sole protein source for 16 weeks in adulthood. Relative to mice fed normal chow, a high fat/casein diet led to increased tumor promotion, hepatocyte proliferation, steatosis, and inflammation. Replacing casein with soy protein isolate counteracted these effects. The high fat diets also resulted in a general increase in transcripts for Wnt/?-catenin pathway components, which may be an important mechanism, whereby hepatic tumorigenesis is promoted. However, soy protein isolate did not block Wnt signaling in this nonalcoholic fatty liver disease model. We conclude that replacing casein with soy protein isolate blocks development of steatosis, inflammation, and tumor promotion in diethylnitrosamine-treated mice fed high fat diets. Impact statement The impact of dietary components on cancer is a topic of great interest for both the general public and the scientific community. Liver cancer is currently the second leading form of cancer deaths worldwide. Our study has addressed the effect of the protein source on hepatic tumor promotion in a mouse model reflecting aspects of non-alcoholic fatty liver disease (NAFLD). A high-fat liquid diet with casein as the protein source promotes hepatic injury and tumor promotion in diethylnitrosamine-treated mice. Replacing casein with a soy protein isolate led to a pronounced diminishment of tumor promotion and associated hepatic injury and inflammation. The study thus demonstrates that a dietary protein source can have beneficial, preventative effects on hepatic tumor promotion.

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Genistein protects female nonobese diabetic mice from developing type 1 diabetes when fed a soy- and alfalfa-free diet.

Publications

Genistein protects female nonobese diabetic mice from developing type 1 diabetes when fed a soy- and alfalfa-free diet.

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