Phytoestrogenic Effects of Fungally Induced Isoflavonoids in Legumes
Food and Feed Safety Research
2009 Annual Report
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.
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.
The earlier investigations using lab assays and animal testing confirmed that the active stress-induced compound produced in soybean, glyceollin I (from a mixture of glyceollins I, II, and III), has inhibitory activity against several breast cancer cell types. The types of cancer also include two cancer cell lines that do not react to the anticancer drug tamoxifen, and also a prostate cancer cell line. Our research examined the molecular effects of the glyceollins on human prostate cancer cell LNCaP to further elucidate its potential effects on prostate cancer prevention. We found that the glyceollins inhibited LNCaP cell growth similar to that of another soy compound, the isoflavone genistein. The growth inhibitory effects of glyceollins and genistein appeared to be through increased production of specific enyzmes in the system. In addition, glyceollin treatments led to production of lower levels of male characteristic factors (androgen responsive genes). In contrast to genistein, this effect of glyceollins on androgen responsive genes appeared to be mediated through modulation of an estrogen- but not androgen-mediated pathway. Hence, the glyceollins exerted multiple effects on LNCaP cells that may be considered cancer preventive and the mechanisms of action appeared to be different from other soy-derived phytochemicals. In vivo experiments demonstrated that the glyceollins were effective inhibitors of prostate cancer cell growth. Progress by cooperators was monitored through routine teleconferencing, meetings, and scientific presentations of information relating to the project at professional society meetings and conferences.