Estrogen replacement therapy (ERT) is widely used to decrease symptoms associated with menopause and to protect women against osteoporosis. ERT, composed of estrogens, equilin, and equilenin, is associated with increased risk of breast, ovarian, and endometrial cancers. As the major metabolites of estrogen and equine estrogen generate oxidative DNA damage and, in some cases react with DNA to form covalent adducts, it is possible that DNA damage plays a central role in the initiation of estrogen-associated cancers. The proposed studies are designed to determine the level of covalent DNA adducts and oxidative damage generated in mammary and reproductive tissues of rats treated with equine estrogens or their metabolites, as well as establish the mutagenic and repair potential of equine estrogen-derived DNA adducts. Leukocytes and endometrial tissue will be collected from women receiving ERT and analyzed for DNA adducts using ultrasensitive 32P-postlabeling and HPLC/electrochemical detection techniques developed in our laboratory. If such adducts are not fully repaired, DNA lesions will persist in target tissues where they may initiate breast, ovarian, and/or endometrial cancer. By demonstrating that certain components of ERT are genotoxic and by defining the biochemical mechanism involved, it should be possible to design drugs that retain desirable therapeutic properties of ERT but lack its carcinogenic effects. This research will also provide biomarkers that can be used to identify subgroups of women at high risk of developing ERT-induced cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES012408-05
Application #
7618442
Study Section
Cancer Etiology Study Section (CE)
Program Officer
Heindel, Jerrold
Project Start
2005-08-04
Project End
2011-04-30
Budget Start
2009-05-01
Budget End
2011-04-30
Support Year
5
Fiscal Year
2009
Total Cost
$273,654
Indirect Cost
Name
State University New York Stony Brook
Department
Pharmacology
Type
Schools of Medicine
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
Suzuki, Naomi; Liu, Xiaoping; Laxmi, Y R Santosh et al. (2011) Anti-breast cancer potential of SS5020, a novel benzopyran antiestrogen. Int J Cancer 128:974-82
Okahashi, Yumiko; Iwamoto, Takaaki; Suzuki, Naomi et al. (2010) Quantitative detection of 4-hydroxyequilenin-DNA adducts in mammalian cells using an immunoassay with a novel monoclonal antibody. Nucleic Acids Res 38:e133
Laxmi, Y R Santosh; Liu, Xiaoping; Suzuki, Naomi et al. (2010) Anti-breast cancer potential of SS1020, a novel antiestrogen lacking estrogenic and genotoxic actions. Int J Cancer 127:1718-26
Okamoto, Yoshinori; Liu, Xiaoping; Suzuki, Naomi et al. (2010) Equine estrogen-induced mammary tumors in rats. Toxicol Lett 193:224-8
Poon, Kinning; Itoh, Shinji; Suzuki, Naomi et al. (2008) Miscoding properties of 6alpha- and 6beta-diastereoisomers of the N(2)-(estradiol-6-yl)-2'-deoxyguanosine DNA adduct by Y-family human DNA polymerases. Biochemistry 47:6695-701
Okamoto, Yoshinori; Chou, Pei-Hsin; Kim, Sung Yeon et al. (2008) Oxidative DNA damage in XPC-knockout and its wild mice treated with equine estrogen. Chem Res Toxicol 21:1120-4
Yasui, Manabu; Suzuki, Naomi; Liu, Xiaoping et al. (2007) Mechanism of translesion synthesis past an equine estrogen-DNA adduct by Y-family DNA polymerases. J Mol Biol 371:1151-62
Yasui, Manabu; Laxmi, Y R Santosh; Ananthoju, Sreenivasa R et al. (2006) Translesion synthesis past equine estrogen-derived 2'-deoxyadenosine DNA adducts by human DNA polymerases eta and kappa. Biochemistry 45:6187-94
Itoh, Shinji; Shibutani, Shinya; Ikegami, Masazumi et al. (2006) Synthesis of oligodeoxynucleotides containing a single 6alpha- or 6beta-diastereoisomer of N2-(estradiol-6-yl)-2'-deoxyguanosine. Chem Res Toxicol 19:450-6
Kim, Sung Yeon; Suzuki, Naomi; Laxmi, Y R Santosh et al. (2006) Antiestrogens and the formation of DNA damage in rats: a comparison. Chem Res Toxicol 19:852-8