Poster Presentation 2014 International Biophysics Congress

Probing and perturbing the lateral organization of cell-surface proteins with plasmonic nanoparticles (#469)

Chiara Paviolo 1 , James W.M. Chon 1 , Andrew H.A. Clayton 1
  1. Swinburne University of Technology, Hawthorn, VIC, Australia

Overexpression of the epidermal growth factor receptor (EGFR) has been observed in many solid tumors, and it has been shown to affect cell proliferation, apoptosis, angiogenesis and metastatic expansion [1, 2]. The receptor activates upon binding of the EGF peptide to the extracellular domain, leading to dimerization or activation of pre-existing dimers [3]. New classes of therapeutic agents aim to block the receptor dimerization, with possible consequences in cell proliferation and apoptosis [2].
In this research, plasmonic nanoparticles (NPs) were used to investigate and block the spatial receptor organization that controls the EGFR signalling activity in HeLa cells. NPs of different shapes (spheres, rods) and dimensions were functionalized with EGF for subsequent EGFR binding by direct thiolation of the protein [2]. Verification of the particle functionalization was determined with spectroscopy and transmission electron microscopy techniques. These revealed a preferential protein binding site on the tips of the rods. Verification of the receptor binding was performed by imaging the scattered light from the NP-treated cells. Cell proliferation was determined via a colorimetric assay (MTS), showing an inhibition of cell proliferation with the use of the rod-shape particles. To the best of our knowledge, this effect has never been reported before and it appears to be linked to the mechanical blocking of the dimerization configuration. The use of NPs as EGFR blocking agents holds great potential for future studies on measuring the EGFR dimerization length using standard biophysical and plasmonic techniques [4, 5].

  1. Clayton AHA, Walker F, et al. Ligand-induced dimer-tetramer transition during the activation of the cell surface epidermal growth factor receptor-A multidimensional microscopy analysis. J. Biol. Chem. 2005; 280(34):30392-30399.
  2. Razumienko E, Dryden L, Scollard D, Reilly RM. MicroSPECT/CT imaging of co-expressed HER2 and EGFR on subcutaneous human tumor xenografts in athymic mice using In-111-labeled bispecific radioimmunoconjugates. Breast Cancer Res. Treat. 2013; 138(3):709-718.
  3. Abulrob A, Lu Z, et al. Nanoscale imaging of epidermal growth factor receptor clustering: effects of inhibitors. J. Biol. Chem. 2010; 285(5):3145-3156.
  4. Clayton AHA, Orchard SG, Nice EC, Posner RG, Burgess AW. Predominance of activated EGFR higher-order oligomers on the cell surface. Growth Factors 2008 2008; 26(6):316-324.
  5. Sönnichsen C, Reinhard BM, Liphardt J, Alivisatos AP. A molecular ruler based on plasmon coupling of single gold and silver nanoparticles. Nat. Biotechnol. 2005; 23(6):741-745.