Crosstalk to Stromal Fibroblasts Induces Resistance of Lung Cancer to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

目的：表皮生长因子受体(EGFR)基因突变的肺癌对吉非替尼和厄洛替尼有良好的临床疗效，对表皮生长因子受体(EGFR)有选择性的TKI治疗，但这些肿瘤往往会产生耐药性。宿主基质细胞被发现对癌细胞的行为有相当大的影响。然而，宿主细胞在癌细胞对受体酪氨酸激酶抑制剂(TKIs)敏感性上的作用知之甚少。因此，我们评估了基质细胞和携带EGFR突变的肺癌细胞之间的串扰对EGFR-TKIs易感性的影响。实验设计：我们评估了具有EGFR激活突变的肺癌细胞PC-9和HCC827与成纤维细胞共培养并共同注射到SCID小鼠中时吉非替尼的敏感性。结果：人成纤维细胞系和原代培养的成纤维细胞均能产生不同水平的HGF。肺癌细胞明显募集成纤维细胞。当肺癌细胞与产生HGF的成纤维细胞在体外共培养并共同注射到SCID小鼠中时，肺癌细胞对EGFR-TKIs产生了抗药性。重要的是，联合使用吉非替尼和抗HGF抗体或HGF拮抗剂，NK4在体内外都成功地克服了成纤维细胞诱导的EGFR-TKI耐药。在小鼠移植瘤模型和肺癌患者标本中均检测到成纤维细胞和HGF的共存。结论：间质成纤维细胞的串扰在肺癌对EGFR-TKI耐药中起关键作用，可能成为EGFR激活突变肺癌的理想治疗靶点。

Purpose : Lung cancers with EGFR activating mutations show good clinical response to gefitinib and erlotinib, selective TKIs to epidermal growth factor receptor (EGFR), but these tumors invariably develop drug resistance. Host stromal cells have been found to have a considerable effect on the behavior of cancer cells. Little is known, however, about the role of host cells on the sensitivity of cancer cells to receptor tyrosine kinase inhibitors (TKIs). We have therefore assessed the effect of crosstalk between stromal cells and lung cancer cells harboring EGFR mutations on susceptibility to EGFR-TKIs.Experimental design : We evaluated the gefitinib sensitivity of lung cancer cells with EGFR activating muations, PC-9 and HCC827, when co-cultured with fibroblasts and co-injected into SCID mice. We also examined the effect of lung cancer cells to fibroblasts recruitment.Results : Both human fibroblast cell lines and primary cultured fibroblasts produced various level of HGF. Lung cancer cells markedly recruited fibroblasts. The lung cancer cells became resistant to EGFR-TKIs when co-cultured in vitro with HGF-producing fibroblasts and co-injected into SCID mice. Importantly, combined use of gefitinib plus anti-HGF antibody or the HGF antagonist, NK4 successfully overcame the fibroblast-induced EGFR-TKI resistance both in vitro and in vivo. Co-localization of fibroblasts and HGF was detected in both xenograft tumors in mouse model and lung cancer patient specimens.Conclusions : These findings indicate that crosstalk to stromal fibroblasts plays a critical role in lung cancer resistance to EGFR-TKIs and may be an ideal therapeutic target in lung cancer with EGFR activating mutations.