title: 4-Hydroxytamoxifen, an active metabolite of tamoxifen, does not alter the radiation sensitivity of MCF-7 breast carcinoma cells irradiated in vitro.
abstract: The effect of 4-hydroxytamoxifen (4OH-TAM), the potent anti-estrogenic metabolite of tamoxifen, on the radiosensitivity of MCF-7 cells irradiated in vitro was determined. Radiation dose response curves were generated for MCF-7 cells maintained and irradiated in phenol red-free medium containing 10(-10) M estradiol (E2) with or without 10(-7) M 4OH-TAM. Immediately after irradiation cells were transferred to medium containing 10(-10) ME2 supplemented with bovine serum to stimulate colony formation. Estradiol-stimulated cell proliferation was inhibited by 10(-7) M 4OH-TAM, but radiation sensitivity was not significantly altered (p > 0.3). Continued incubation in the absence of E2 for an additional 24 hours after irradiation likewise failed to alter the radiosensitivity of 4OH-TAM-treated MCF-7 cells. These studies indicate that growth-inhibitory concentrations of the anti-estrogen 4OH-TAM do not modify the in vitro radiation sensitivity of this line of human breast carcinoma cells.
authors.affiliation: Department of Human Oncology, University of Wisconsin, Madison 53792.
authors.forename: J N
authors.initials: JN
authors.lastname: Sarkaria
authors.forename: E M
authors.initials: EM
authors.lastname: Miller
authors.forename: C J
authors.initials: CJ
authors.lastname: Parker
authors.forename: V C
authors.initials: VC
authors.lastname: Jordan
authors.forename: R T
authors.initials: RT
authors.lastname: Mulcahy
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D002277:Carcinoma / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D005260:Female; D006801:Humans; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000187:drug effects*; D013629:Tamoxifen / Q000031:analogs & derivatives* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D013629:Tamoxifen; C016601:afimoxifene