Frogne Thomas, Benjaminsen Rikke V, Sonne-Hansen Katrine, Sorensen Boe S, Nexo Ebba, Laenkholm Anne-Vibeke, Rasmussen Louise M, Riese David J, de Cremoux Patricia, Stenvang Jan, Lykkesfeldt Anne E
Department of Tumor Endocrinology, Institute of Cancer Biology, Danish Cancer Society, Copenhagen, Denmark.
Breast Cancer Res Treat. 2009 Mar;114(2):263-75. doi: 10.1007/s10549-008-0011-8. Epub 2008 Apr 14.
Seven fulvestrant resistant cell lines derived from the estrogen receptor alpha positive MCF-7 human breast cancer cell line were used to investigate the importance of epidermal growth factor receptor (ErbB1-4) signaling. We found an increase in mRNA expression of EGFR and the ErbB3/ErbB4 ligand heregulin2 (hrg2) and a decrease of ErbB4 in all resistant cell lines. Western analyses confirmed the upregulation of EGFR and hrg2 and the downregulation of ErbB4. Elevated activation of EGFR and ErbB3 was seen in all resistant cell lines and the ErbB3 activation occurred by an autocrine mechanism. ErbB4 activation was observed only in the parental MCF-7 cells. The downstream kinases pAkt and pErk were increased in five of seven and in all seven resistant cell lines, respectively. Treatment with the EGFR inhibitor gefitinib preferentially inhibited growth and reduced the S phase fraction in the resistant cell lines concomitant with inhibition of Erk and unaltered Akt activation. In concert, inhibition of Erk with U0126 preferentially reduced growth of resistant cell lines. Treatment with ErbB3 neutralizing antibodies inhibited ErbB3 activation and resulted in a modest but statistically significant growth inhibition of two resistant cell lines. These data indicate that ligand activated ErbB3 and EGFR, and Erk signaling play important roles in fulvestrant resistant cell growth. Furthermore, the decreased level of ErbB4 in resistant cells may facilitate heterodimerization of ErbB3 with EGFR and ErbB2. Our data support that a concerted action against EGFR, ErbB2 and ErbB3 may be required to obtain complete growth suppression of fulvestrant resistant cells.
从雌激素受体α阳性的MCF-7人乳腺癌细胞系衍生出的7个氟维司群耐药细胞系，被用于研究表皮生长因子受体（ErbB1 - 4）信号传导的重要性。我们发现，在所有耐药细胞系中，表皮生长因子受体（EGFR）和ErbB3/ErbB4配体这里调节蛋白2（hrg2）的mRNA表达增加，而ErbB4减少。蛋白质免疫印迹分析证实了EGFR和hrg2的上调以及ErbB4的下调。在所有耐药细胞系中均观察到EGFR和ErbB3的激活增强，且ErbB3的激活是通过自分泌机制发生的。仅在亲本MCF-7细胞中观察到ErbB4的激活。下游激酶pAkt和pErk在7个耐药细胞系中的5个以及所有7个耐药细胞系中分别增加。用EGFR抑制剂吉非替尼处理可优先抑制耐药细胞系的生长并降低S期比例，同时抑制Erk且不改变Akt的激活。与此一致，用U0126抑制Erk可优先降低耐药细胞系的生长。用ErbB3中和抗体处理可抑制ErbB3的激活，并导致两个耐药细胞系出现适度但具有统计学意义的生长抑制。这些数据表明，配体激活的ErbB3和EGFR以及Erk信号传导在氟维司群耐药细胞的生长中起重要作用。此外，耐药细胞中ErbB4水平的降低可能促进ErbB3与EGFR和ErbB2的异二聚化。我们的数据支持，可能需要协同作用对抗EGFR、ErbB2和ErbB3，才能完全抑制氟维司群耐药细胞的生长。
