New steroidal aromatase inhibitors: Suppression of estrogen-dependent breast cancer cell proliferation and induction of cell death

Table 1 Effects of steroids 3a (A) and 4a (B) on cell cycle distribution of human breast cancer MCF-7aro cells.

A	Control	T	T + 3a1 μM	T + 3a10 μM	T + 3a25 μM	T + 3a50 μM
G₀/G₁	91.3 ± 2.1	42.4 ± 2.3 *	52.4 ± 6.8 ^φ	53.6 ± 2.2 ^φ	65.9 ± 2.1 ^φ	72.2 ± 1.5 ^φ
S	4.8 ± 1.2	48.4 ± 2.3 *	39.7 ± 5.5 ^φ	38.3 ± 6.5 ^φ	25.8 ± 3.3 ^φ	19.6 ± 4.2 ^φ
G₂/M	5.0. ± 2.1	10.2 ± 2.4	9.94 ± 1.7	7.2 ± 4.6	7.4 ± 2.7	8.9 ± 2.6
B	Control	T	T + 4a1 μM	T + 4a10 μM	T + 4a25 μM	T + 4a50 μM
G₀/G₁	91.3 ± 2.2	42.4 ± 2.3 *	58.6 ± 18.0	43.6 ± 1.4	59.6 ± 2.2 ^φ	78.2 ± 2.3 ^φ
S	4.8 ± 1.2	48.4 ± 2.3 *	33.8 ± 17.3	43.4 ± 3.5	35.3 ± 0.1**	18.9 ± 1.8 ^φ
G₂/M	5.0 ± 2.1	10.2 ± 2.4	10.7 ± 1.4	13.1 ± 1.9	4.1 ± 2.2	3.0 ± 0.1

Cells were treated with different concentrations of the compounds for 24 hr. Treated cells were harvested, fixed and their DNA content was evaluated by PI labelling followed by flow cytometry analysis. Data are presented as single cell events in G0–G1, S and the G2-M phases of the cell cycle. The data represents means and SE of triplicates and are representative of three independent experiments. Significant differences between the control (medium without hormones) and medium containing 1 nM T are indicated by * (P < 0.0001); medium containing 1 nM T vs medium containing different steroid concentrations are indicated as φ (P < 0.001), ** (P < 0.01) and θ(P < 0.05).

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