Modulation of Estrogen-Depurinating DNA Adducts by Sulforaphane for Breast Cancer
Abstract
Sulforaphane (SFN), a bioavailable phytochemical found in young broccoli, is a potent inducer of detoxification enzymes such as NAD(P)H:quinone oxidoreductase (NQO1) and glutathione-S-transferase (GST) via the Kelch-like ECH-associated protein 1 (Keap1) - Nuclear Factor- E2-related factor (Nrf2) signaling pathway. To test the hypothesis that SFN may be an ideal chemoprevention agent to block estrogen-mediated carcinogenesis, we treated the ER-negative, nontumorigenic human breast epithelial MCF10A cell line with either vehicle or SFN (10 M) and E2 or 4-OHE2. Results show that NQO1 was up-regulated at the mRNA (~2fold), protein (~3fold) and activity levels (~3fold) by SFN treatment. Estrogen metabolites and depurinating DNA adducts in the cell culture medium were partially purified by solid phase extraction and then analyzed by UHPLC- ESI-MS/MS. Following E2 treatment, the depurinated adducts 4-OHE(sub 1/2)-1-N3Ade and 4-OHE 1/2-1-N7Gua were significantly lower in SFN treated cells compared to vehicle (0.03 0.01 versus 0.07 0.02 pmole/106cell, p=0.0294); 4-OHE(sub 1/2)- glutathione conjugates were significantly higher following SFN treatment (1.54 0.37 versus 0.83 0.19 pmole/106cell, p=0.0015) as were 4-OCH3E(sub 1/2) (5.36 0.16 versus 1.81 0.20pmole/106cell,p<0.0001) levels. Following treatment with the proximate metabolite 4-OHE2, 4-OHE(sub 1/2)-1-N3Ade and 4-OHE 1/2-1-N7Gua were again significantly lower in SFN treated cells compared to vehicle (0.59 0.11 versus 1.42 0.16 pmole/106cell, p=0.0028) while 4-OHE(sub 1/2)-glutathione-conjugates (4.44 0.52 versus 0.87 0.03 pmole/106cell,p=0.0001) and 4-OCH3E(sub 1/2) levels were significantly higher (195.00 12.33 versus 58.05 1.77pmole/106cell, p<.00001).
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2012
- Accession Number
- ADA564470
Entities
People
- Yang Li
Organizations
- University of Pittsburgh