Original Research ARTICLE
Compartment model predicts VEGF secretion and investigates the effects of VEGF Trap in tumor-bearing mice
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
Angiogenesis, the formation of new blood vessels from existing vasculature, is important in tumor growth and metastasis. A key regulator of angiogenesis is vascular endothelial growth factor (VEGF), which has been targeted in numerous anti-angiogenic therapies aimed at inhibiting tumor angiogenesis. Systems biology approaches, including computational modeling, are useful for understanding this complex biological process and can aid in the development of novel and effective therapeutics that target the VEGF family of proteins and receptors. We have developed a computational model of VEGF transport and kinetics in the tumor-bearing mouse, which includes three-compartments: normal tissue, blood, and tumor. The model simulates human tumor xenografts and includes human (VEGF121 and VEGF165) and mouse (VEGF120 and VEGF164) isoforms. The model incorporates molecular interactions between these VEGF isoforms and receptors (VEGFR1 and VEGFR2), as well as co-receptors (NRP1 and NRP2). We also include important soluble factors: soluble VEGFR1 (sFlt-1) and α-2-macroglobulin. The model accounts for transport via macromolecular transendothelial permeability, lymphatic flow, and plasma clearance. We have fit the model to available in vivo experimental data on the plasma concentration of free VEGF Trap and VEGF Trap bound to mouse and human VEGF in order to estimate the rates at which parenchymal cells (myocytes and tumor cells) and endothelial cells secrete VEGF. Interestingly, the predicted tumor VEGF secretion rates are significantly lower (0.007–0.023 molecules/cell/s, depending on the tumor microenvironment) than most reported in vitro measurements (0.03–2.65 molecules/cell/s). The optimized model is used to investigate the interstitial and plasma VEGF concentrations and the effect of the VEGF-neutralizing agent, VEGF Trap (aflibercept). This work complements experimental studies performed in mice and provides a framework with which to examine the effects of anti-VEGF agents, aiding in the optimization of such anti-angiogenic therapeutics as well as analysis of clinical data. The model predictions also have implications for biomarker discovery with anti-angiogenic therapies.
Keywords: systems biology, mathematical model, computational model, angiogenesis, tumor xenograft model, anti-angiogenic therapy, cancer
Citation: Finley SD, Dhar M and Popel AS (2013) Compartment model predicts VEGF secretion and investigates the effects of VEGF Trap in tumor-bearing mice. Front. Oncol. 3:196. doi: 10.3389/fonc.2013.00196
Received: 21 December 2012; Accepted: 13 July 2013;
Published online: 30 July 2013.
Edited by:Katarzyna Anna Rejniak, H. Lee Moffitt Cancer Center & Research Institute, USA
Reviewed by:Roya Khosravi-Far, Massachusetts Institute of Technology, USA
Katie Bentley, Cancer Research UK, UK
Copyright: © 2013 Finley, Dhar and Popel. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Stacey D. Finley, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA e-mail: email@example.com