Abstract Patients with non–small cell lung cancer (NSCLC) EGFR mutations have shown a dramatic response to EGFR inhibitors (EGFR-TKI). EGFR T790M mutation and MET amplification have been recognized as major mechanisms of acquired resistance to EGFR-TKI. Therefore, MET inhibitors have recently been used in NSCLC patients in clinical trials. In this study, we tried to identify the mechanism of acquired resistance to MET inhibitors. We analyzed the antitumor effects of two MET inhibitors, PHA-665752 and crizotinib, in 10 NSCLC cell lines. EBC-1 cells with MET amplification were the only cells that were sensitive to both MET inhibitors. We established PHA-665752–resistant EBC-1 cells, namely EBC-1R cells. Activation of KRAS, EGFR, and FGFR2 signaling was observed in EBC-1R cells by FISH and receptor tyrosine kinase phosphorylation antibody arrays. EBC-1R cells also showed overexpression of ATP-binding cassette subfamily B member 1 (ABCB1) as well as phosphorylation of MET. EBC-1R cells grew as cell spheres that exhibited cancer stem cell–like (CSC) properties and epithelial–mesenchymal transition (EMT). The level of miR-138 that targeted ABCB1 was decreased in EBC-1R cells. ABCB1 siRNA and the ABCB1 inhibitor elacridar could reduce sphere numbers and suppress EMT. Elacridar could also reverse resistance to PHA-665752 in EBC-1R cells. Our study demonstrated that ABCB1 overexpression, which was associated with CSC properties and EMT, was involved in the acquired resistance to MET inhibitors. Inhibition of ABCB1 might be a novel therapeutic strategy for NSCLC patients with acquired resistance to MET inhibitors. Mol Cancer Ther; 14(11); 2433–40. ©2015 AACR.

Supplemental Figure 1:Protein levels of p-MET, MET and ABCB1 were examined in 7 SQ cell lines by Western blot analysis Supplemental Figure 2: FGFR inhibition overcomes the resistance to PHA-665752 in EBC-1R cells Supplemental Figure 3: ABCB1 overexpression in cloned EBC-1R cells Supplemental Figure 4: Immunohistochemical staining for ABCB1 protein expression in tumor cells from SQ patients

Cell lines and drugs Clinical samples and Immunohistochemical staining

Supplemental Table 1. Gene copy numbers of MET, EGFR and KRAS in EBC-1R cells Supplemental Table 2. MiRNAs correlated with the sensitivity to PHA665752 Supplemental Table 3. ABCB1 protein expression in 50 lung squamous cell cancer patients　

Overcoming acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) is critical in combating EGFR-mutant non-small cell lung cancer (NSCLC). We tried to construct a novel therapeutic strategy to conquer the resistance to second-and third-generation EGFR-TKIs in EGFR-positive NSCLC patients. We established afatinib- and osimertinib-resistant lung adenocarcinoma cell lines. Exome sequencing, cDNA array and miRNA microarray were performed using the established cell lines to discover novel therapeutic targets associated with the resistance to second-and third-generation EGFR-TKIs. We found that ANKRD1 which is associated with the epithelial-mesenchymal transition (EMT) phenomenon and anti-apoptosis, was overexpressed in the second-and third-generation EGFR-TKIs-resistant cells at the mRNA and protein expression levels. When ANKRD1 was silenced in the EGFR-TKIs-resistant cell lines, afatinib and osimertinib could induce apoptosis of the cell lines. Imatinib could inhibit ANKRD1 expression, resulting in restoration of the sensitivity to afatinib and osimertinib of EGFR-TKI-resistant cells. In EGFR-mutant NSCLC patients, ANKRD1 was overexpressed in the tumor after the failure of EGFR-TKI therapy, especially after long-duration EGFR-TKI treatments. ANKRD1 overexpression which was associated with EMT features and anti-apoptosis, was commonly involved in resistance to second-and third-generation EGFR-TKIs. ANKRD1 inhibition could be a promising therapeutic strategy in EGFR-mutant NSCLC patients.

BACKGROUND/AIM Recent clinical trials have shown that immune checkpoint blockades that target either PD-1 or PD-L1 yield remarkable responses in a subgroup of patients with non-small cell lung cancer (NSCLC). MATERIALS AND METHODS We retrospectively examined, by immunohistochemical analysis, 211 NSCLC samples. Using 32 independent samples, we also evaluated PD-L1 expression in NSCLC patients with EGFR gene mutations treated by EGFR-TKIs. RESULTS Overall survival of PD-L1-positive stages I-III NSCLC and stage I NSCLC and stages I-III squamous cell carcinoma (SQ) were significantly shorter than those of PD-L1-negative NSCLC (p<0.01 and p=0.02 and p=0.01, respectively). In stage I NSCLC and stages I-III SQ, PD-L1 expression was found to be independent predictor of death after multivariate analysis. Response to EGFR-TKIs was not significantly different between PD-L1-positive and PD-L1-negative NSCLC patients with EGFR mutations. CONCLUSION PD-L1 expression was a significant independent predictor of poor outcome in NSCLC patients.

AXL, a receptor tyrosine kinase implicated in cell survival, proliferation, and migration, is also associated with acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor therapy. However, its prognostic significance in lung adenocarcinoma (AD) remains unclear. We therefore evaluated the prognostic significance of the expression of AXL and/or its ligand, growth arrest specific 6 (GAS6), in completely resected lung AD. We evaluated the relationship between AXL, GAS6, and vimentin expression, as determined by immunohistochemistry (IHC) analysis, with overall survival and disease-free survival in 113 patients with stages I-III lung AD. Protein expression was also assayed using western blot analysis in 10 lung AD cell lines. AXL-positive (AXL(+)), GAS6-positive (GAS6(+)), or AXL(+)/GAS6(+) staining was significantly associated with vimentin-positive (vimentin) expression. AXL(+)/GAS6(+) and vimentin showed a negative tendency toward an association with EGFR mutation. AXL(+), GAS6(+), or AXL(+)/GAS6(+) status significantly correlated with poor overall survival. In stage I cases, AXL(+)/VGAS6(+) status significantly correlated with poor overall survival and disease-free survival, especially in cases with wild-type EGFR. In multivariate analysis, AXL/GAS6 classifications in stage I as well as in stages I-III lung AD were found to be independent factors for poor patient outcomes. Unlike lung AD cell lines with mutant EGFR, almost all cells with wild-type EGFR showed AXL and vimentin co-expression as determined by western blotting. AXL(+) and GAS6(+) expression is relevant to a poor prognosis in resected lung AD patients at stage I. AXL/GAS6 might serve as crucial predictive and prognostic biomarkers and targets to identify individuals at high risk of post-operative death.

BACKGROUND/AIM:We evaluated the usefulness of reverse transcription-polymerase chain reaction (RT-PCR) for detecting anaplastic lymphoma kinase (ALK) translocations using cytology samples from lung cancer patients.MATERIALS AND METHODS:We analyzed ALK translocations by RT-PCR in cytology samples from lung cancer patients diagnosed at the Nippon Medical School Hospital between 2013 and 2015. Immunochemistry (IHC) and break-apart fluorescence in situ hybridization (FISH) were also performed on available tissue samples.RESULTS:A total of 155 cytology samples were analyzed in our study. We obtained 115 (68%) samples from bronchial lavage. We were able to determine 153 (99%) results by RT-PCR with 4 (3%) positive samples. The four samples positive by RT-PCR were also positive by IHC and FISH performed on the tissue samples collected simultaneously.CONCLUSION:RT-PCR is a suitable method for detecting ALK translocations using cytology samples from patients with primary lung cancer, especially when tissue samples are not available.

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.

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.