Epidermal growth factor receptor lacking C-terminal autophosphorylation sites retains signal transduction and high sensitivity to epidermal growth factor receptor tyrosine kinase inhibitor
Epidermal growth factor receptor lacking C-terminal autophosphorylation sites retains signal transduction and high sensitivity to epidermal growth factor receptor tyrosine kinase inhibitor
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DOI：
10.1111/j.1349-7006.2008.01071.x
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发表时间：
2009-03-01
期刊：
影响因子：
5.7
通讯作者：
Nishio, Kazuto
中科院分区：
文献类型：
--
作者：
Maegawa, Mari;Arao, Tokuzo;Nishio, Kazuto
表皮生长因子受体（EGFR）（delE746_A750）的组成型活性突变通过EGFR C-末端区域酪氨酸残基的磷酸化激活下游信号，如ERK和Akt。这些途径被认为对细胞对EGFR酪氨酸激酶抑制剂（TKI）的敏感性很重要。为了检测EGFR C-末端区域中酪氨酸残基的磷酸化与细胞对EGFR TKI的敏感性之间的相关性，我们使用野生型（wt）EGFR以及以下构建体：delE746_A750 EGFR;在C-末端区域中7个酪氨酸残基被苯丙氨酸取代的delE746_A750 EGFR;和在氨基酸980处具有C-末端截短的delE746_A750 EGFR。将这些构建体稳定转染到HEK 293细胞中，并分别命名为HEK 293/Wt、HEK 293/D、HEK 293/D 7 F和HEK 293/D-Tr。发现HEK 293/D细胞对EGFR TKI（AG 1478）的敏感性是HEK 293/Wt的100倍。令人惊讶的是，HEK 293/D 7 F和HEK 293/D-Tr细胞，用缺乏C-末端自磷酸化位点的EGFR转染，保留了对EGFR TKI的高敏感性。在这三种高敏感性细胞中，ERK通路在没有配体刺激的情况下被激活，这被EGFR TKI抑制。此外，尽管HEK 293/D 7 F和HEK 293/D-Tr细胞中的EGFR缺乏用于EGFR信号转导的显著酪氨酸残基，但Src同源性和胶原同源性（Shc）的磷酸化在这些细胞中自发活化。我们的研究结果表明，EGFR的C-末端区域中的酪氨酸残基不是细胞对EGFR TKI敏感性所必需的，并且可能存在一种未知的EGFR信号传导途径，其独立于EGFR的C-末端区域。（Cancer Sci 2009; 100：552-557）。
Constitutively active mutations of epidermal growth factor receptor (EGFR) (delE746_A750) activate downstream signals, such as ERK and Akt, through the phosphorylation of tyrosine residues in the C-terminal region of EGFR. These pathways are thought to be important for cellular sensitivity to EGFR tyrosine kinase inhibitors (TKI). To examine the correlation between phosphorylation of the tyrosine residues in the C-terminal region of EGFR and cellular sensitivity to EGFR TKI, we used wild-type (wt) EGFR, as well as the following constructs: delE746_A750 EGFR; delE746_A750 EGFR with substitution of seven tyrosine residues to phenylalanine in the C-terminal region; and delE746_A750 EGFR with a C-terminal truncation at amino acid 980. These constructs were transfected stably into HEK293 cells and designated HEK293/Wt, HEK293/D, HEK293/D7F, and HEK293/D-Tr, respectively. The HEK293/D cells were found to be 100-fold more sensitive to EGFR TKI (AG1478) than HEK293/Wt. Surprisingly, the HEK293/D7F and HEK293/D-Tr cells, transfected with EGFR lacking the C-terminal autophosphorylation sites, retained high sensitivity to EGFR TKI. In these three high-sensitivity cells, the ERK pathway was activated without ligand stimulation, which was inhibited by EGFR TKI. In addition, although EGFR in the HEK293/D7F and HEK293/D-Tr cells lacked significant tyrosine residues for EGFR signal transduction, phosphorylation of Src homology and collagen homology (Shc) was spontaneously activated in these cells. Our results indicate that tyrosine residues in the C-terminal region of EGFR are not required for cellular sensitivity to EGFR TKI, and that an as-yet-unknown signaling pathway of EGFR may exist that is independent of the C-terminal region of EGFR. (Cancer Sci 2009; 100: 552-557).