Histone acetylation decreased by estradiol in the MCF-7 human mammary cancer cell line

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Abstract
The effect of estradiol (E2) on the [3H]-acetylation of nuclear histones was studied in the MCF-7 human mammary cancer cell line in culture. Cells (~ 108) were incubated with 8 × 10−6M [3H]-acetate in the absence (control) or in the presence of estradiol (10−5–10−8M). After 20 min incubation, the nuclear histones were extracted and separated by electrophoresis, and each histone band was measured and calculated in DPM/mg protein. It was observed that only the H2 + H3 and H4 histones were associated with the [3H]-acetate. Estradiol (10−6–10−8M) provoked a significant inhibition in the incorporation of the acetate. The negative effect, in percentage of the non-treated cell value, was as follows: in E2 (10−6M): − 25 ± 10 (SE) for H2 + H3 and − 26 ± 5 for H4; in E2 (10−7M): − 35 ± 9 and − 39 ± 10; and in E2 (10−8M): − 56 ± 22 and − 30 ± 13 respectively. It is concluded that estradiol has a negative effect in the acetylation of H2, H3 and H4 histones of this mammary cancer cell; no acetylation or effect is observed in H1 histones. The relationship of this finding to the biological responses of the hormone is to be explored.