Biomedical Radiation Sciences, Department of Radiology, Oncology and Radiation Science, Uppsala University, Uppsala, Sweden.
PLoS One. 2011;6(9):e24739. doi: 10.1371/journal.pone.0024739. Epub 2011 Sep 12.
The tyrosine kinase inhibitor gefitinib inhibits growth in some tumor types by targeting the epidermal growth factor receptor (EGFR). Previous studies show that the affinity of the EGF-EGFR interaction varies between hosting cell line, and that gefitinib increases the affinity for some cell lines. In this paper, we investigate possible mechanisms behind these observations. Real-time interaction analysis in LigandTracer® Grey revealed that the HER2 dimerization preventing antibody pertuzumab clearly modified the binding of ¹²⁵I-EGF to EGFR on HER2 overexpressing SKOV3 cells in the presence of gefitinib. Pertuzumab did not affect the binding on A431 cells, which express low levels of HER2. Cross-linking measurements showed that gefitinib increased the amount of EGFR dimers 3.0-3.8 times in A431 cells in the absence of EGF. In EGF stimulated SKOV3 cells the amount of EGFR dimers increased 1.8-2.2 times by gefitinib, but this effect was cancelled by pertuzumab. Gefitinib treatment did not alter the number of EGFR or HER2 expressed in tumor cell lines A431, U343, SKOV3 and SKBR3. Real-time binding traces were further analyzed in a novel tool, Interaction Map, which deciphered the different components of the measured interaction and supports EGF binding to multiple binding sites. EGFR and HER2 expression affect the levels of EGFR monomers, homodimers and heterodimers and EGF binds to the various monomeric/dimeric forms of EGFR with unique binding properties. Taken together, we conclude that dimerization explains the varying affinity of EGF-EGFR in different cells, and we propose that gefitinib induces EGFR dimmers, which alters the interaction characteristics with ¹²⁵I-EGF.
酪氨酸激酶抑制剂吉非替尼通过靶向表皮生长因子受体 (EGFR) 抑制某些肿瘤类型的生长。先前的研究表明，EGF-EGFR 相互作用的亲和力在宿主细胞系之间有所不同，并且吉非替尼增加了一些细胞系的亲和力。在本文中，我们研究了这些观察结果背后的可能机制。在 LigandTracer® Grey 中进行的实时相互作用分析表明，HER2 二聚体化阻止抗体 pertuzumab 明显改变了在存在吉非替尼的情况下，过表达 HER2 的 SKOV3 细胞中 ¹²⁵I-EGF 与 EGFR 的结合。Pertuzumab 不影响 A431 细胞的结合，A431 细胞表达低水平的 HER2。交联测量表明，在没有 EGF 的情况下，吉非替尼使 A431 细胞中 EGFR 二聚体的量增加了 3.0-3.8 倍。在 EGF 刺激的 SKOV3 细胞中，吉非替尼使 EGFR 二聚体的量增加了 1.8-2.2 倍，但 pertuzumab 取消了这种作用。吉非替尼处理不会改变肿瘤细胞系 A431、U343、SKOV3 和 SKBR3 中 EGFR 或 HER2 的表达数量。实时结合痕迹进一步在一种新工具 Interaction Map 中进行了分析，该工具解析了测量相互作用的不同组成部分，并支持 EGF 与多个结合位点结合。EGFR 和 HER2 表达影响 EGFR 单体、同二聚体和异二聚体的水平，并且 EGF 以独特的结合特性与各种单体/二聚体形式的 EGFR 结合。总之，我们得出结论，二聚化解释了不同细胞中 EGF-EGFR 的亲和力变化，并且我们提出吉非替尼诱导 EGFR 二聚体，这改变了与 ¹²⁵I-EGF 的相互作用特征。
