RT Journal Article
SR Electronic
T1 Tamoxifen-Induced Adduct Formation and Cell Stress in Human Endometrial Glands
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 200
OP 207
DO 10.1124/dmd.109.029488
VO 38
IS 1
A1 Helén Andersson
A1 Malin Helmestam
A1 Anna Zebrowska
A1 Matts Olovsson
A1 Eva Brittebo
YR 2010
UL http://dmd.aspetjournals.org/content/38/1/200.abstract
AB The beneficial effects of tamoxifen in the prevention and treatment of breast cancer are compromised by an increased risk of endometrial polyps, hyperplasia, and cancer. Tamoxifen is metabolized to an array of metabolites with estrogenic effects but also to reactive intermediates that may form protein and DNA adducts. The aim of this study was to investigate cellular [3H]tamoxifen adduct formation by light microscopic autoradiography and cell stress by immunohistochemical analysis of glucose-regulating protein 78 (GRP78), nuclear factor κB (NF-κB), and caspase 3 in human endometrial explants after short-term incubation with tamoxifen. The cellular expression of tamoxifen-metabolizing enzymes in human endometrial biopsy samples was also determined by immunohistochemistry. The results showed selective [3H]tamoxifen adduct formation in glandular and surface epithelia after incubation with a nontoxic concentration of [3H]tamoxifen (6 nM). There was also a selective expression of the endoplasmic reticulum stress chaperone GRP78 and activated caspase 3 at these sites after incubation with cytotoxic concentrations of tamoxifen (10–100 μM). The cell stress was preferentially observed in samples from women in the proliferative menstrual phase. No treatment-related expression of NF-κB was observed. Constitutive expression of the tamoxifen-metabolizing enzymes CYP1B1, CYP2A6, CYP2B6, CYP2C8/9/19, CYP2D6, and SULT2A1 in glandular and surface epithelia was shown, but there was a large interindividual variation. The colocalization of [3H]tamoxifen adducts, expression of GRP78, caspase 3, and tamoxifen-metabolizing enzymes in human glandular and surface epithelia suggest a local bioactivation of tamoxifen at these sites and that epithelial cells are early target sites for tamoxifen-induced cell stress. Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics