1a.Objectives (from AD-416)
Utilize microbial elicitors of isoflavonoid production in manipulation of isoflavonoid levels. Test individual or combinations of isoflavonoid compounds induced by microbial elicitors for phytoestrogenic effects in animal systems. Test effects of phytoalexins using in vitro cell systems for PPAR transcriptional activity, adipocyte differentiation, and obesity related gene expression. Evaluate in vivo gene expression from tissue samples from ongoing experiments.
1b.Approach (from AD-416)
Estrogenic and antiestrogenic activities of isoflavonoids isolated from soybean tissues/organs will be analyzed by determining their ability to support in vitro and in vivo growth of several different cancer cell lines. Compounds will be screened for estrogen activity in assays using breast cancer cells incorporating an estrogen dependent promoter coupled with a luciferase reporter gene. Compounds will be assayed in order to determine synergistic effects and to measure estrogenic potency. Also, compounds will be screened for estrogen receptor binding and breast cancer proliferation. Anitestrogenic activity will be determined for all compounds. Antiestrogenic compounds will be tested in vivo using a mouse model system with different cancer cell lines, including breast, ovarian, and prostate cells.
Soybean contains many health promoting compounds that include the isoflavones. When stressed soybean produces a mixture of 3 glyceollins that has shown antiestrogenic activity, including the ability to inhibit breast, ovarian, and prostate cancer. This past year further progress was made examining the different activities of the 3 individual glyceollins in several cancer assays. Glyceollin I has shown potent anticancer activity and is the major component of the glyceollin mixture. Glyceollin III has shown slight estrogenic activity in several assays. Recent identification by the United States Department of Agriculture (USDA) of low abundance compounds glyceollidins I and II has led us to examine their estrogenic activity. Ongoing studies are focusing on the relative binding and gene expression activities of these compounds and a manuscript is in preparation. The glyceollidins as well as glycinol may represent compounds with potent activity that may have beneficial effects on diabetes and obesity. Based upon the glyceollin structure, we generated a series of synthetic analogs based on the soy daidzein backbone. These studies in collaboration with USDA and Xavier University were published. These studies have also generated a patent application on the anti-estrogenic and anti-cancer activity of the analogs series. Our early work revealed a potent in vivo suppression of cancer growth in a xenograft animal model of breast cancer. During this study we also revealed activity of glyceollins on inhibition of cancer growth that did not involve estrogen, and discovered the glyceollins suppress a specific kinase (enzyme) involved in cancer cell growth. Building upon the kinase targeting activity of glyceollins we have begun to investigate their activity in difficult to treat estrogen receptor-negative breast cancer cell systems. Ongoing studies have demonstrated that the glyceollins can suppress cancer growth and metastasis (spreading to other organs) of estrogen receptor-negative cancer. These data provide evidence that the glyceollins may represent a more universally useful anti-cancer agent. Glyceollins stimulated glucose uptake (basal and insulin stimulated) in adipocytes (fat cells). Preliminary data suggest that the glyceollins regulate glucose through a GLUT (glucose transporter) receptor. The ability of the glyceollins to stimulate glucose uptake, similar to insulin, would enable a glyceollin-enriched food to ameliorate the symptoms of diabetes and assist in the management of insulin resistance. Research progress was monitored through teleconferencing, frequent email communications and reports.