No abstract

High expression levels of TrkB and BDNF are associated with aggressive malignant behavior in tumor cells and a poor prognosis in patients with various types of cancer. In this study, we aimed to identify the relationship between TrkB and BDNF expression and clinicopathological variables and prognosis in non-small cell lung cancer (NSCLC). We evaluated TrkB and BDNF expression in the tumor cells of 102 NSCLC patients by immunohistochemistry. Out of all clinicopathological factors examined, only vascular invasion was significantly correlated with TrkB (P=0.010) and BDNF (P=0.015) expression. TrkB-positive tumors had significantly worse disease-free survival (P=0.0094) and overall survival (P=0.0019) than TrkB-negative tumors, and TrkB expression was an independent prognostic factor for disease-free survival (HR 3.735, 95% CI 1.560-11.068, P=0.002) and overall survival (HR 4.335, 95% CI 1.534-15.963, P=0.004) in multivariate analysis. Finally, our analysis revealed that co-expression of TrkB and BDNF conferred poorer prognosis compared with overexpression of either protein alone. Our results indicate that expression of TrkB and BDNF is associated with poor prognosis in NSCLC patients.

PurposeErlotinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), and bevacizumab, an anti-vascular endothelial growth factor (VEGF) agent, are promising therapies for advanced non-small cell lung cancer (NSCLC). Our study was aimed to determine whether there were conditions under which the addition of bevacizumab would enhance the antitumor activity of erlotinib against NSCLC tumors in vitro and in vivo.MethodsMTS was for NSCLC cell (PC9, 11–18, H1975, H157, H460 and A549) growth assay in vitro. ELISA was for VEGF protein assay in cells and tumor tissues. Mouse xenograft models were established with H157, H460 and A549 with primary resistance to erlotinib and treated with erlotinib plus bevacizumab or each agent alone. Erlotinib concentrations in tumors were determined by high-performance liquid chromatography.ResultsBevacizumab alone did not inhibit NSCLC cell growth in vitro. In primarily erlotinib-resistant NSCLC cells, the levels of VEGF protein were highest in H157 cell followed in order by H460 and A549 cells. In vivo, bevacizumab alone significantly inhibited tumor growth only in xenograft models with high (H157) and/or moderate (H460) levels of VEGF protein. A combination of erlotinib and bevacizumab partially reversed resistance to erlotinib in H157 xenografts (high VEGF level) with increasing intratumoral erlotinib concentrations, but not in H460 (moderate) or A549 (low) xenografts.ConclusionsThese results support that combined with anti-VEGF therapy could enhance antitumor activity of anti-EGFR therapy and/or partially reverse resistance to EGFR TKI, by increasing EGFR TKI concentration in specific tumors that express high levels of VEGF protein.Electronic supplementary materialThe online version of this article (doi:10.1007/s00280-014-2610-x) contains supplementary material, which is available to authorized users.

The presence of epidermal growth factor receptor (EGFR) somatic mutations in non-small-cell lung cancer patients is associated with response to treatment with EGFR-tyrosine kinase inhibitors, such as gefitinib and erlotinib. More than 100 mutations in the kinase domain of EGFR have been identified. In particular there are many variations of deletion mutations in exon 19. In this study, using yellow fluorescent protein-tagged fragments of the EGFR intracellular domain, we examined the differences in sensitivity to gefitinib, erlotinib and afatinib between several exon 19 mutants and other common EGFR mutations. We also used serum of patients undergoing treatment with EGFR-tyrosine kinase inhibitors in this system. In addition, we examined the relative kinase activity of these mutants by measuring relative fluorescent intensity after immunofluorescence staining. We found that both sensitivity to EGFR-tyrosine kinase inhibitors and relative kinase activity differed among several EGFR mutations found in the same region of the kinase domain. This study underscores the importance of reporting the clinical outcome of treatment in relation to different EGFR mutations. (Cancer Sci 2013; 104: 584-589)

Nearly one half of all cases of acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) for non-small-cell lung cancer (NSCLC) are due to the T790M mutation in EGFR exon 20. The T790M mutation is a C→T transition mutation at a CpG dinucleotide. DNA methylation of cytosine (5-methylcytosine (5-mC)) in CpG dinucleotides is a common DNA modification; CpG dinucleotides are considered to be mutational hotspots that cause genetic diseases and cancers through spontaneous deamination of 5-mC, resulting in C→T transition mutations. This study aimed to examine the methylation level of cytosine of EGFR codon 790 and investigate whether DNA methylation was involved in acquiring the T790M mutation. We examined 18 NSCLC tumor tissues, 7 normal lymph node tissues, and 4 NSCLC cell lines (PC9, HCC827, 11-18, and A549). 5-mC was checked by bisulfite sequencing and quantified by pyrosequencing. We found that all tissue samples and cell lines had 5-mC in EGFR codon 790. The 5-mC range was 58.4-90.8%. Our results imply that hypermethylation of the CpG dinucleotide in EGFR codon 790 leads to the C→T transition mutation, causing resistance to EGFR-TKI treatment.