VEGF is an important mediator of tumor angiogenesis in malignant lesions in a genetically engineered mouse model of lung adenocarcinoma

Bharat K Majeti, Joseph H Lee, Brett H Simmons, Farbod Shojaei

BACKGROUND: VEGF is one of the key drivers of physiological or pathological angiogenesis hence several VEGF inhibitors are in different stages of clinical development. To further dissect the role of VEGF in different stages of tumor progression in lung tumors, we utilized KrasG12D-LSL GEMMs (genetically engineered mouse models). METHODS: Intranasal delivery of adenoviruses expressing cre recombinase in KrasG12D-LSL mice results in the expression of mutant Kras that leads to development of tumor lesions ranging from adenomatous hyperplasia to large adenoma and adenocarcinoma over time in lung. In the current study, we treated KrasG12D-LSL mice at 14 weeks post inhalation with three different angiogenic inhibitors including axitinib and PF-00337210 both of which are selective inhibitors of VEGFR and sunitinib which targets VEGFR, C-SF1-R, PDGFR and KIT. RESULTS: Pathology findings showed no significant difference in percentage of adenomatous hyperplastic lesions between the vehicle vs. any of the treatments suggesting that angiogenesis may not play a major role at early stages of tumorigenesis. However, each inhibitor suppressed percentage of benign adenoma lesions and almost fully inhibited growth of adenocarcinoma lesions in the recipients which was consistent with a reduction in tumor vasculature. Treatment with sunitinib which is a multi-targeted RTKI did not provide any advantage compared to selective VEGFR inhibitor further emphasizing role of VEGF in tumor angiogenesis in this model. CONCLUSION: Overall, our studies indicate significance of VEGF and angiogenesis in a spontaneous model of lung tumorigenesis and provide a proof of mechanism for anti-cancer activity of VEGF inhibitors in this model.