| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
|
|---|
| Research Abstract |
Estrogens that originate from humans and animals are thought of as a factor of endocrine disruptors in the environment. We investigated their halogenated derivatives, which could be produced by chlorine treatment at a sewage treatment plant. The chlorinated derivatives of estrone (El), 17p-estradiol (E2), estriol (E3), and 17a-ethynylestradiol (EE2) were produced by the reaction with hypochlorous acid in organic solvents and also brominated derivatives when bromide ions were present. The estrogenic activities of the halogenated derivatives were measured by yeast two-hybrid assays incorporating the human estrogen receptor a (hERα) or medaka fish (Oryzias latipes) estrogen receptor a (medERα). Although the activities of 4-CIE1 and 10-chloro-l,4-estradiene-3,17-dione were similar to those of El, the activities of 2-C1E1 and 2,4-diCIE1 were approximately 4/5 and 1/50 that of El, respectively, in an agonist assay for hERα. No activity was detected in 2,4,16,16-tetraClE1. The estrogenicities of chlorinated derivatives of E2, E3, and EE2 showed a similar tendency to that of El. The brominated derivatives showed slightly weaker activity than the corresponding chlorinated derivatives. Similar results were obtained in a devised GFP expression system in human breast carcinoma MCF7 cells and in their cell proliferation assay. In fact, chlorinated derivatives of El, 2-ClE1, 4-C1E1 and 2,4-diClE1 in the effluent of a municipal sewage treatment plant located in Shizuoka prefecture, Japan were detected. The effects of chlorinated derivatives of El and E2 on the gene expression levels in MCF7 cells were analyzed by real-time quantitative PCR. The levels of two well-studied estrogen-responsive genes, pS2 and PgR, increased corresponding to the estrogenicity of chlorinated derivatives. On the other hand, AhR taeget gene, Cyplal levels were decreased.
|
