Abstract. Nintedanib (BIBF1120) is a multi-targeted angiokinase inhibitor and has been evaluated in idiopathic pulmonary fibrosis and advanced non-small cell lung cancer

Nintedanib (BIBF1120) is a multi-targeted angiokinase inhibitor and has been evaluated in idiopathic pulmonary fibrosis and advanced non-small cell lung cancer (NSCLC) patients in clinical studies. In the present study, we evaluated the antitumor effects of nintedanib in 16 NSCLC cell lines and tried to identify microRNA (miRNA) associated with sensitivity to nintedanib. No correlations between FGFR, PDGFR and VEGFR family activation and sensitivity to nintedanib were found. The difference in miRNA expression profiles between 5 nintedanib-sensitive and 5 nintedanib-resistant cell lines was evaluated by miRNA array and quantitative RT-PCR analysis (qRT-PCR). Expression of miR-200b, miR-200a and miR-141 belonging to the miR-200 family which contributes to epithelial-mesenchymal transition (EMT), was significantly lower in 5 nintedanib-resistant than in 5 nintedanib-sensitive cell lines. We examined the protein expression of EMT markers in these 10 NSCLC cell lines. E-cadherin expression was lower, and vimentin and ZEB1 expression were higher in 5 nintedanib-resistant cell lines. PC-1 was the most sensitive of the NSCLC cell lines to nintedanib. We established nintedanib-resistant PC-1 cells (PC-1R) by the stepwise method. PC-1R cells also showed decreased expression of miR-200b, miR-141 and miR-429 and increased expression of ZEB1 and ZEB2. We confirmed that induction of miR-200b or miR-141 enhanced sensitivity to nintedanib in nintedanib-resistant A549 and PC1-R cells. In addition, we evaluated the response to gefitinib in combination with nintedanib after TGF-β1 exposure of A549 cells. Nintedanib was able to reverse TGF-β1-induced EMT and resistance to gefitinib caused by miR-200b and miR-141 upregulation and ZEB1 downregulation. These results suggested that the miR-200/ZEB axis might be predictive biomarkers for sensitivity to nintedanib in NSCLC cells. Furthermore, nintedanib combined with gefitinib might be a novel therapeutic strategy for NSCLC cells with EMT phenotype and resistance to gefitinib.