Vendrell J A, Bieche I, Desmetz C, Badia E, Tozlu S, Nguyen C, Nicolas J C, Lidereau R, Cohen P A
CNRS UMR 5160, Faculté de Pharmacie, 15 Av Charles Flahault, BP 14491, 34093 Montpellier Cedex 5, France.
Endocr Relat Cancer. 2005 Mar;12(1):75-92. doi: 10.1677/erc.1.00899.
The aim of this study was to explore the pharmacological response to 4-hydroxy-tamoxifen (OH-Tam) and to estradiol (E2) in three cell lines: MVLN, a human breast carcinoma cell line derived from MCF-7, and two MVLN-derived OH-Tam-resistant (OTR) cell lines, called CL6.8 and CL6.32. The OH-Tam response in the OTR cells was associated with the development of both an agonist activity of the drug on cell proliferation and the resistance of the cells to OH-Tam-induced apoptosis. The OTR cells also developed an increased sensitivity to the E2 growth-stimulating activity. To delineate the genes that determine such responses, we combined a mini-array-based gene-selection approach and an extensive real-time quantitative PCR exploration in the MVLN and OTR cell lines exposed to three pharmacological conditions: a 4-day treatment with E2, OH-Tam or both E2 and OH-Tam. Compiled data revealed a hyper-response to E2 and a modification of the OH-Tam pharmacological response (loss of antagonist action and agonist activity) at the gene-expression level. The proteins encoded by the genes selected in this study have been reported to be involved in the regulation of cell proliferation, cell transformation, DNA repair and apoptosis, or belong to the ErbB/epidermal growth factor receptor-driven pathway. Our data also provide evidence of changes in transcriptional co-regulator expression, elevated mitogen-activated protein kinase activity and increase in the phosphorylation status of estrogen receptor alpha on serine residue 118 in the OTR cell lines, suggesting the possible involvement of such mechanisms in the agonist activity of OH-Tam and/or the hyper-response of cells to E2. Taken together, our study should enhance our knowledge of the multifactorial events associated with the development of Tam resistance in two independent cell lines issued from the same selection process and should help in the identification of potential molecular targets for diagnosis or therapy.
本研究的目的是探究三种细胞系对4-羟基他莫昔芬（OH-他莫昔芬）和雌二醇（E2）的药理反应：MVLN，一种源自MCF-7的人乳腺癌细胞系，以及两种源自MVLN的OH-他莫昔芬耐药（OTR）细胞系，分别称为CL6.8和CL6.32。OTR细胞中OH-他莫昔芬的反应与该药物对细胞增殖的激动剂活性以及细胞对OH-他莫昔芬诱导的凋亡的抗性的发展有关。OTR细胞对E2的生长刺激活性也表现出更高的敏感性。为了确定决定此类反应的基因，我们在暴露于三种药理条件下的MVLN和OTR细胞系中，结合了基于微阵列的基因选择方法和广泛的实时定量PCR探索：用E2、OH-他莫昔芬或E2与OH-他莫昔芬联合处理4天。汇总的数据显示，在基因表达水平上，对E2有超反应，且OH-他莫昔芬的药理反应发生了改变（拮抗剂作用和激动剂活性丧失）。本研究中选择的基因所编码的蛋白质据报道参与细胞增殖、细胞转化、DNA修复和凋亡的调控，或属于ErbB/表皮生长因子受体驱动的途径。我们的数据还提供了转录共调节因子表达变化、丝裂原活化蛋白激酶活性升高以及OTR细胞系中雌激素受体α丝氨酸残基118磷酸化状态增加的证据，表明这些机制可能参与OH-他莫昔芬的激动剂活性和/或细胞对E2的超反应。综上所述，我们的研究应能增进我们对同一选择过程产生的两个独立细胞系中与他莫昔芬耐药发展相关的多因素事件的了解，并有助于识别诊断或治疗的潜在分子靶点。
