Somaï Sonia, Chaouat Marc, Jacob Denis, Perrot Jean-Yves, Rostène William, Forgez Patricia, Gompel Anne
INSERM U339, Hôpital Saint-Antoine, Paris, France.
Int J Cancer. 2003 Jul 10;105(5):607-12. doi: 10.1002/ijc.11147.
Estrogens promote cell proliferation in normal and transformed mammary epithelial cells by inducing expression of hormone-responsive genes involved in the cell cycle. The action of antiestrogens is therefore central in regard to their potent inhibitory effects on estrogen-induced cell growth. We used normal human epithelial breast cells from primary cultures (HBE cells) to study hormonal (estrogen and antiestrogen) regulation on 3 key proteins involved in the apoptotic process: Bcl-2, p53 and caspase-3. The mammary adenocarcinoma cell line, MCF-7, was also used to study the molecular regulation of Bcl-2. In both HBE and MCF-7 cells, we found that estradiol (E2) induced an increase in Bcl-2 mRNA levels. This effect was counteracted in the presence of a pure antiestrogen, ICI 182780 (ICI). Alone, ICI did not modify either the Bcl-2 protein or mRNA levels in HBE cells, whereas in MCF-7, a strong downregulation of Bcl-2 mRNA was observed. In parallel, in HBE cells, we observed that E2 caused a decrease in p53 and caspase-3 protein levels, whereas ICI alone increased p53 and caspase-3 protein levels. The ICI effects on p53 and caspase-3 were partially counteracted by E2. Under the same experimental conditions, ICI exerts a potent pro-apoptotic effect, which was not counteracted by E2. In contrast, 4-hydroxytamoxifen was slightly weaker as a pro-apoptotic agent in HBE cells and its effects were reversed by E2. We demonstrate that in HBE cells, ICI reverses the anti-apoptotic action of E2 and alone acts as a highly potent pro-apoptotic molecule. These results provide new insight into treatment for breast cancer prevention.
雌激素通过诱导参与细胞周期的激素反应基因的表达，促进正常和转化的乳腺上皮细胞的增殖。因此，抗雌激素的作用对于其对雌激素诱导的细胞生长的强大抑制作用至关重要。我们使用来自原代培养的正常人乳腺上皮细胞（HBE细胞）来研究激素（雌激素和抗雌激素）对凋亡过程中涉及的3种关键蛋白的调节：Bcl-2、p53和caspase-3。乳腺腺癌细胞系MCF-7也用于研究Bcl-2的分子调节。在HBE和MCF-7细胞中，我们发现雌二醇（E2）诱导Bcl-2 mRNA水平升高。在纯抗雌激素ICI 182780（ICI）存在的情况下，这种作用被抵消。单独使用ICI不会改变HBE细胞中Bcl-2蛋白或mRNA水平，而在MCF-7中，观察到Bcl-2 mRNA的强烈下调。同时，在HBE细胞中，我们观察到E2导致p53和caspase-3蛋白水平降低，而单独使用ICI则增加p53和caspase-3蛋白水平。ICI对p53和caspase-3的作用被E2部分抵消。在相同的实验条件下，ICI发挥强大的促凋亡作用，且未被E2抵消。相反，4-羟基他莫昔芬在HBE细胞中作为促凋亡剂的作用稍弱，其作用被E2逆转。我们证明，在HBE细胞中，ICI逆转E2的抗凋亡作用，并且单独作为一种高效的促凋亡分子起作用。这些结果为乳腺癌预防治疗提供了新的见解。
