(A-31) VEGF/PDGF cross family heterodimerization: A new paradigm to growth factor signaling with significance in health and disease.

Introduction:: Angiogenesis, the process by which new blood vessels form, is crucial for normal organ development and repair. However, disruptions to this process has been linked to numerous diseases such as obesity[1], cancer[2] and other diseases[2]–[6]. Despite the development of angiogenesis targeted therapies to address these diseases, such approaches are incomplete as they do not consider the several signaling axes regulating angiogenesis. Cross-family signaling is one of the more recent paradigms for controlling angiogenesis, in which growth factors (GFs) from one family bind to and signal through receptors from another family[7]. Another novel theory which is emerging is ligand heterodimerization, where for instance, members of the vascular endothelial growth factor (VEGF) family, VEGF-A and placental growth factor (PlGF), can heterodimerize if co-expressed in the same cell. Indeed, the VEGF-A--PlGF heterodimer is implicated in tumor angiogenesis[8]. In this study, we aim to expand our understanding of the scope of ligand heterodimerization through systematic growth factor screening.

Materials and Methods:: We used SPR to examine the 1:1 binding of PDGF, VEGF, and ANG growth factors to one another. We immobilized VEGFA on the sensor chip (Planar Polyethylene Glycol/Carboxyl) on a SPR machine (Reichert 4SPR, Reichert, Inc.). Initially single concentration of different growth factors such as PDGF-AA, -BB, -AB, -CC, -DD, and ANG4 were passed to determine the possible interfamily interaction. Further to determine the kinetics of the interaction’s multiple concentrations of each growth factor between 3 nm to 50 nM were passed over VEGFA and responses were recorded. All the interactions were allowed for 180s association and 300s dissociation followed by regeneration with 100 mM H₃PO₄ for 120s. The resultant curves were reference subtracted and fitted into 1:1 kinetics fitting in TraceDrawer (Ridgeview Instruments, Sweden). The quality of data and fitting was assessed by the U-value and chi² value.


Results, Conclusions, and Discussions:: Results and Discussion: We found that PDGF-AA exhibits very strong binding with VEGFA with an equilibrium dissociation constant (KD, affinity) of 900 pM. While ANG-4 has the least interaction with VEGFA, reporting an affinity of 1 µM. Although these are preliminary results, they still open a new paradigm of cross-family ligand heterodimerization and binding possibilities of different cross-family growth factors, specifically between VEGFs and PDGFs.

Conclusion: The findings present an expanded role of growth factor cross-signaling with significance in health and disease, particularly in understanding anti-angiogenic drug resistance and cardiovascular-dependent diseases and other related studies.

Acknowledgements (Optional): : This material is based upon work supported by the National Science Foundation under Grant No. 1923151. Research reported in this publication was also supported by the National Institute of Heart, Lung, and Blood of the National Institutes of Health under Award Number. 7R01HL159946-02. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the National Institutes of Health.

References (Optional): : [1] [1] C. M. Kusminski, P. E. Bickel, and P. E. Scherer, ‘Targeting adipose tissue in the treatment of obesity-associated diabetes’, Nature Reviews Drug Discovery 2016 15:9, vol. 15, no. 9, pp. 639–660, Jun. 2016, doi: 10.1038/nrd.2016.75.

[2] [2] P. Carmeliet, ‘Angiogenesis in life, disease and medicine’, Nature, vol. 438, no. 7070, pp. 932–936, Dec. 2005, doi: 10.1038/NATURE04478.

[3] [3] G. Cao, X. Xuan, R. Zhang, J. Hu, and H. Dong, ‘Gene Therapy for Cardiovascular Disease: Basic Research and Clinical Prospects’, Front Cardiovasc Med, vol. 8, p. 1523, Nov. 2021, doi: 10.3389/FCVM.2021.760140.

[4] [4] B. H. Annex, ‘Therapeutic angiogenesis for critical limb ischaemia’, Nature Reviews Cardiology 2013 10:7, vol. 10, no. 7, pp. 387–396, May 2013, doi: 10.1038/nrcardio.2013.70.

[5] [5] R. Gupta, J. Tongers, and D. W. Losordo, ‘Human Studies of Angiogenic Gene Therapy’, Circ Res, vol. 105, no. 8, pp. 724–736, Oct. 2009, doi: 10.1161/CIRCRESAHA.109.200386.

[6] [6] F. Mac Gabhann, B. H. Annex, and A. S. Popel, ‘Gene Therapy from the perspective of Systems Biology’.

[7] [7] S. B. Mamer et al., ‘Discovery of High-Affinity PDGF-VEGFR Interactions: Redefining RTK Dynamics’, doi: 10.1038/s41598-017-16610-z.

[8] [8] V. Tarallo et al., ‘A placental growth factor variant unable to recognize vascular endothelial growth factor (VEGF) receptor-1 inhibits VEGF-dependent tumor angiogenesis via heterodimerization’, Cancer Res, vol. 70, no. 5, pp. 1804–1813, Mar. 2010, doi: 10.1158/0008-5472.CAN-09-2609.