4-Hydroxytamoxifen, an active metabolite of tamoxifen, does not alter the radiation sensitivity of MCF-7 breast carcinoma cells irradiated in vitro

Jann N. Sarkaria, Elizabeth M. Miller, Christopher J. Parker, V. Craig Jordan, R. Timothy Mulcahy

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42 Scopus citations


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 M E2 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.

Original languageEnglish (US)
Pages (from-to)159-165
Number of pages7
JournalBreast Cancer Research and Treatment
Issue number2
StatePublished - Jan 1994



  • 4-hydroxytamoxifen
  • MCF-7 cells
  • growth inhibition
  • radiation sensitivity
  • tamoxifen

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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