VEGF receptor-2 (VEGFR-2 or
kinase insert domain receptor; KDR) is a known endothelial target also expressed in NSCLC
tumor cells. We investigated the association between alterations in the KDR gene and clinical outcome in patients with resected
non-small-cell lung carcinoma (NSCLC; n = 248). KDR copy number gains (CNG), measured by quantitative PCR and fluorescence in situ hybridization, were detected in 32% of
tumors and associated with significantly higher KDR
protein and higher microvessel density than
tumors without CNGs. KDR CNGs were also associated with significantly increased risk of death (HR = 5.16; P = 0.003) in patients receiving adjuvant
platinum-based
chemotherapy, but no differences were observed in patients not receiving adjuvant
therapy. To investigate potential mechanisms for these associations, we assessed NSCLC cell lines and found that KDR CNGs were significantly associated with in vitro resistance to
platinum chemotherapy as well as increased levels of nuclear
hypoxia inducible factor-1α (HIF-1α) in both NSCLC
tumor specimens and cell lines. Furthermore, KDR knockdown experiments using
small interfering RNA reduced
platinum resistance, cell migration, and HIF-1α levels in cells bearing KDR CNGs, providing evidence for direct involvement of KDR. No KDR mutations were detected in exons 7, 11, and 21 by PCR-based sequencing; however, two variant single nucleotide polymorphism genotypes were associated with favorable overall survival in
adenocarcinoma patients. Our findings suggest that
tumor cell KDR CNGs may promote a more malignant phenotype including increased chemoresistance, angiogenesis, and HIF-1α levels, and that KDR CNGs may be a useful
biomarker for identifying patients at high risk for recurrence after adjuvant
therapy, a group that may benefit from
VEGFR-2 blockade.