Daniel A R, Gaviglio A L, Knutson T P, Ostrander J H, D'Assoro A B, Ravindranathan P, Peng Y, Raj G V, Yee D, Lange C A
Departments of Medicine and Pharmacology, Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
Department of Medicine, Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
Oncogene. 2015 Jan 22;34(4):506-15. doi: 10.1038/onc.2013.579. Epub 2014 Jan 27.
Progesterone and estrogen are important drivers of breast cancer proliferation. Herein, we probed estrogen receptor-α (ER) and progesterone receptor (PR) cross-talk in breast cancer models. Stable expression of PR-B in PR-low/ER+ MCF7 cells increased cellular sensitivity to estradiol and insulin-like growth factor 1 (IGF1), as measured in growth assays performed in the absence of exogenous progestin; similar results were obtained in PR-null/ER+ T47D cells stably expressing PR-B. Genome-wide microarray analyses revealed that unliganded PR-B induced robust expression of a subset of estradiol-responsive ER target genes, including cathepsin-D (CTSD). Estradiol-treated MCF7 cells stably expressing PR-B exhibited enhanced ER Ser167 phosphorylation and recruitment of ER, PR and the proline-, glutamate- and leucine-rich protein 1 (PELP1) to an estrogen response element in the CTSD distal promoter; this complex co-immunoprecipitated with IGF1 receptor (IGFR1) in whole-cell lysates. Importantly, ER/PR/PELP1 complexes were also detected in human breast cancer samples. Inhibition of IGF1R or phosphoinositide 3-kinase blocked PR-B-dependent CTSD mRNA upregulation in response to estradiol. Similarly, inhibition of IGF1R or PR significantly reduced ER recruitment to the CTSD promoter. Stable knockdown of endogenous PR or onapristone treatment of multiple unmodified breast cancer cell lines blocked estradiol-mediated CTSD induction, inhibited growth in soft agar and partially restored tamoxifen sensitivity of resistant cells. Further, combination treatment of breast cancer cells with both onapristone and IGF1R tyrosine kinase inhibitor AEW541 was more effective than either agent alone. In summary, unliganded PR-B enhanced proliferative responses to estradiol and IGF1 via scaffolding of ER-α/PELP1/IGF1R-containing complexes. Our data provide a strong rationale for targeting PR in combination with ER and IGF1R in patients with luminal breast cancer.
孕酮和雌激素是乳腺癌增殖的重要驱动因素。在此，我们在乳腺癌模型中探究了雌激素受体α（ER）和孕酮受体（PR）的相互作用。在无外源性孕激素的生长试验中，PR低/ER+ MCF7细胞中PR-B的稳定表达增加了细胞对雌二醇和胰岛素样生长因子1（IGF1）的敏感性；在稳定表达PR-B的PR缺失/ER+ T47D细胞中也得到了类似结果。全基因组微阵列分析显示，未结合配体的PR-B诱导了一部分雌二醇反应性ER靶基因的强烈表达，包括组织蛋白酶D（CTSD）。用雌二醇处理稳定表达PR-B的MCF7细胞，可增强ER丝氨酸167磷酸化，并使ER、PR以及富含脯氨酸、谷氨酸和亮氨酸的蛋白1（PELP1）募集至CTSD远端启动子中的雌激素反应元件；该复合物在全细胞裂解物中与IGF1受体（IGFR1）共同免疫沉淀。重要的是，在人乳腺癌样本中也检测到了ER/PR/PELP1复合物。抑制IGF1R或磷酸肌醇3激酶可阻断PR-B依赖的CTSD mRNA因雌二醇而上调。同样，抑制IGF1R或PR可显著减少ER募集至CTSD启动子。内源性PR的稳定敲低或用奥那司酮处理多种未修饰的乳腺癌细胞系，可阻断雌二醇介导的CTSD诱导，抑制软琼脂中的生长，并部分恢复耐药细胞对他莫昔芬的敏感性。此外，用奥那司酮和IGF1R酪氨酸激酶抑制剂AEW541联合处理乳腺癌细胞比单独使用任何一种药物都更有效。总之，未结合配体的PR-B通过含ER-α/PELP1/IGF1R复合物的支架作用增强了对雌二醇和IGF1的增殖反应。我们的数据为在管腔型乳腺癌患者中联合靶向PR与ER和IGF1R提供了有力依据。
