Estrogens and their metabolites have been implicated in the etiology of breast cancer. Tamoxifen is an anti-estrogen that is used in the treatment of breast cancer patients. However, tamoxifen treatment has been associated with endometrial cancer, and has been shown to induce hepatocarcinoma in rodents. The hypothesis driving the proposed research postulates that estrogens and tamoxifen are weak carcinogens in humans, reflecting their ability to form covalent adducts with DNA. The goal of the proposed research is to establish the mutagenic potential of selected tamoxife and estrogen DNA adducts. Oligodeoxynucleotides containing a single defined DN adduct will be prepared from activated forms of estrogens and tamoxifen, or by chemical synthesis. The miscoding properties of these adducts will be quantified. The particular adducts to be studied include estrogen or tamoxifen adducts at the N2 position of Guanine and the N6 position of Adenine, and thes adducts will be generated using various different activated metabolites of estrogen and tamoxifen. Using mammalian DNA polymerases, steady state kinetics will be used to measure frequencies of nucleotide insertion opposite each lesion and chain extension from the 3' terminus. In this way the in vitro miscoding specificity for each adduct will be established. Miscoding propertie will be analyzed under steady-state conditions, using templates with the adducts in different sequence contexts, and using three different mammalian polymerases. Site specifically adducted oligos will also be used to build plasmids in order to establish the miscoding specificity of selected adducts i vivo, in mammalian cells. The proposed experiments are designed to provide quantitative information on the mutagenicity of selected estrogen and anti-estrogen DNA adducts. The tamoxifen DNA adducts prepared for in vitro experiments will also be employed for as standard markers in studies to detect adducts in the DNA of patients undergoing tamoxifen treatment; preliminary studies have established the presence of such adducts in endometrial tissue. Dr. Shibutani will explore the possibility of using the detection of tamoxifen DNA adducts as a biomarker to investigate the relationship between tamoxifen therapy and the development of endometrial cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES009418-04
Application #
6382256
Study Section
Chemical Pathology Study Section (CPA)
Program Officer
Heindel, Jerrold
Project Start
1998-05-13
Project End
2002-09-29
Budget Start
2001-05-01
Budget End
2002-09-29
Support Year
4
Fiscal Year
2001
Total Cost
$178,447
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
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
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; Liu, Xiaoping; Suzuki, Naomi et al. (2008) Increased antitumor potential of the raloxifene prodrug, raloxifene diphosphate. Int J Cancer 122:2142-7
Kim, Sung Yeon; Suzuki, Naomi; Laxmi, Y R Santosh et al. (2006) Inefficient repair of tamoxifen-DNA adducts in rats and mice. Drug Metab Dispos 34:311-7
Yasui, Manabu; Suzuki, Naomi; Laxmi, Y R Santosh et al. (2006) Translesion synthesis past tamoxifen-derived DNA adducts by human DNA polymerases eta and kappa. Biochemistry 45:12167-74
Hashiba, Masamichi; Kasahara, Toshihiko; Kim, Sung Yeon et al. (2006) DNA damage and altered gene expression of enzymes for metabolism and DNA repair by tamoxifen and toremifene in the female rat liver. Cancer Sci 97:468-77
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
Shibutani, Shinya; Kim, Sung Yeon; Suzuki, Naomi (2006) 32P-postlabeling DNA damage assays: PAGE, TLC, and HPLC. Methods Mol Biol 314:307-21

Showing the most recent 10 out of 42 publications