Antiestrogens induce growth inhibition by sequential activation of p38 mitogen-activated protein kinase and transforming growth factor-β pathways in human breast cancer cells
Antiestrogens induce growth inhibition by sequential activation of p38 mitogen-activated protein kinase and transforming growth factor-β pathways in human breast cancer cells
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DOI：
10.1210/me.2003-0278
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发表时间：
2004-07-01
影响因子：
--
通讯作者：
Knabbe, C
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文献类型：
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作者：
Buck, MB;Pfizenmaier, K;Knabbe, C
抗雌激素已成功用于治疗乳腺癌。本研究的目的是探讨不同信号转导通路在抗雌激素诱导的生长抑制中的作用，以深入了解抗雌激素耐药机制。我们使用特异性MAPK抑制剂和MCF-7癌细胞作为模型，证明p38 MAPK是乳腺癌抗雌激素生长抑制的重要介质。激酶测定显示抗雌激素（4-羟基他莫昔芬和 ICI 182.780）可快速诱导 p38 活性。 p38 激酶缺陷突变体的过度表达降低了抗雌激素对细胞周期蛋白 A 转录的抑制。TGFbeta 是乳腺癌细胞生长的负调节因子，由抗雌激素诱导；TGFbeta 是乳腺癌细胞生长的负调节因子。因此，p38 的激活可能是由 TGFbeta 介导的。我们使用 TGFbeta 和抗雌激素敏感报告基因测定来表明 p38 激活先于 TGFbeta 激活。通过抗雌激素诱导的 TGFbeta2 和 TGFbeta 受体 II 转录的定量 RT-PCR 分析进一步证实了这些结果。 p38 的抑制减少了这两个基因的诱导。最后，蛋白质印迹分析表明，抗雌激素通过 p38 诱导 Smad（母亲对抗十五肢麻痹同源物）2 的磷酸化。使用 Smad 依赖性报告基因 p6SBE 进行的启动子测定证实了 Smad3 和 Smad4 参与抗雌激素作用。总之，我们的数据描绘了一个抗雌激素信号转导途径，涉及依次激活 p38 和 TGFbeta 途径以介导生长抑制。
Antiestrogens are successfully used in the treatment of breast cancer. The purpose of this study was to investigate the role of different signal transduction pathways in antiestrogen-induced growth inhibition to gain insights into mechanisms of antiestrogen resistance.We used specific MAPK inhibitors and MCF-7 carcinoma cells as a model to demonstrate that p38 MAPK is an important mediator of antiestrogen growth inhibition in breast cancer. A kinase assay showed that antiestrogens (4-hydroxytamoxifen and ICI 182.780) rapidly induce p38 activity. Overexpression of kinase-deficient mutants of p38 reduced the antiestrogen suppression of Cyclin A transcription.TGFbeta, a negative regulator of breast cancer cell growth, is induced by antiestrogens; therefore, activation of p38 could have been mediated by TGFbeta. We used a TGFbeta and antiestrogen-sensitive reporter gene assay to show that p38 activation precedes TGFbeta activation. These results were further confirmed by quantitative RT-PCR analysis of the antiestrogen-induced transcription of TGFbeta2 and TGFbeta receptor II. Inhibition of p38 reduced the induction of both genes.Finally, Western blot analysis shows that antiestrogens induce phosphorylation of Smad ( mothers against decapentaplegic homolog) 2 via p38. Promoter assays with the Smad-dependent reporter p6SBE confirm participation of Smad3 and Smad4 in antiestrogen action.Taken together, our data delineate an antiestrogen signal transduction pathway involving sequential activation of p38 and TGFbeta pathways to mediate growth inhibition.