Product Research Department, Kamakura Research Laboratories, Chugai Pharmaceutical Co., Ltd., Japan.
Product Research Department, Kamakura Research Laboratories, Chugai Pharmaceutical Co., Ltd., Japan.
Lung Cancer. 2014 Jan;83(1):44-50. doi: 10.1016/j.lungcan.2013.10.003. Epub 2013 Oct 16.
Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) show notable effects against non-small cell lung cancers (NSCLCs) harboring EGFR-activating mutations. However, almost all patients eventually acquire resistance to EGFR-TKIs. In this study, we established novel erlotinib resistant NSCLC cells and examined their resistant mechanisms. Resistant cells were established in 14, 3, and 0 wells exposed to 0.1, 1, and 10 μM erlotinib, respectively. The IC(50) values of these cells were 47- to 1209-fold higher than that of the parent cells. No secondary T790M mutation was detected in any resistant cells. However, in 13/17 resistant cells, EGFR copy number was reduced less than approximately one-eighth of parent cells, and in one resistant cell (B10), >99.99% of the population was EGFR-unamplified cells. Most (97.5%) parent cells showed EGFR amplification, but 2.5% of the population comprised EGFR-unamplified cells. An EGFR-unamplified clone (4D8) isolated from parent cells in erlotinib-free normal medium also showed erlotinib resistance comparable to the resistant B10 cells. Loss of an EGFR-amplified chromosome 7 (EGFR-ampch7) was observed in 4D8 and B10 cells. EGFR-unamplified cells were constantly maintained as a minor population of the parent cells under normal cell culture conditions. In conclusion, loss of an EGFR-ampch7 causes acquired resistance in EGFR-mutated HCC827 cells exposed to a relatively low concentration of erlotinib, but a high concentration prevents the emergence of resistance.
表皮生长因子受体酪氨酸激酶抑制剂（EGFR-TKIs）对携带 EGFR 激活突变的非小细胞肺癌（NSCLC）具有显著疗效。然而，几乎所有患者最终都会对 EGFR-TKIs 产生耐药性。在这项研究中，我们建立了新型的厄洛替尼耐药 NSCLC 细胞，并研究了它们的耐药机制。耐药细胞是在分别暴露于 0.1、1 和 10 μM 厄洛替尼的 14、3 和 0 个孔中建立的。这些细胞的 IC50 值比亲本细胞高 47 到 1209 倍。在任何耐药细胞中均未检测到继发性 T790M 突变。然而，在 17 个耐药细胞中的 13 个中，EGFR 拷贝数减少至亲本细胞的约 1/8 以下，在一个耐药细胞（B10）中，超过 99.99%的细胞群体是 EGFR 非扩增细胞。大多数（97.5%）亲本细胞显示 EGFR 扩增，但 2.5%的细胞群体是 EGFR 非扩增细胞。从厄洛替尼无正常培养基中的亲本细胞分离的 EGFR 非扩增克隆（4D8）也显示出与耐药 B10 细胞相当的厄洛替尼耐药性。在 4D8 和 B10 细胞中观察到 EGFR 扩增染色体 7（EGFR-ampch7）的缺失。在正常细胞培养条件下，EGFR 非扩增细胞作为亲本细胞的一个小亚群持续存在。总之，在相对低浓度的厄洛替尼暴露下，EGFR-ampch7 的缺失导致 EGFR 突变的 HCC827 细胞获得耐药性，但高浓度可防止耐药性的出现。
