1. Inhibition of NMU-induced mammary tumorigenesis by dietary soy
- Author
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Simmen, Rosalia C.M., Eason, Renea R., Till, S. Reneé, Chatman, Leon, Velarde, Michael C., Geng, Yan, Korourian, Sohelia, and Badger, Thomas M.
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PROGESTERONE , *TUMORS , *BLOOD plasma , *APOPTOSIS - Abstract
Abstract: We previously demonstrated that female Sprague–Dawley rats fed AIN-93G diets containing soy protein isolate (SPI+) had lower DMBA-induced mammary tumor incidence than those fed diets containing casein (CAS), due partly to altered Phase I metabolism with soy. Here, we evaluated the tumor protective effects of these same diets to the direct-acting carcinogen N-methyl-nitrosourea (NMU). Tumor incidence was reduced and tumor latency was enhanced, in NMU-administered female rats lifetime exposed to SPI+, relative to the CAS group. Tumor multiplicity did not differ with diet, while tumor grade tended to be more advanced with SPI+. Normal mammary glands of CAS and SPI+ tumor-bearing rats had comparable proliferative and apoptotic status. However, mammary expression of HER-2/neu and progesterone receptor (PR) genes was higher for SPI+ rats. Moreover, tumored SPI+ rats had lower serum progesterone levels than those fed CAS, while serum estrogen did not differ. Serum from tumored SPI+ rats had higher apoptotic activity towards mammary epithelial MCF-7 cells, than CAS serum. Thus, dietary soy protects against mammary tumorigenesis induced by a direct-acting carcinogen and alters signaling pathways involving PR and HER-2/neu. [Copyright &y& Elsevier]
- Published
- 2005
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