Switching the targeting pathways of a therapeutic antibody by nanodesign.

Application of nonmaterial's in medicine is an emerging field with potentials to positively impact human health care [1]. Nanoconjugates of monoclonal antibodies including EGFR (epidermal growth factor receptor) antibody cetuximab (C225), herceptin, are potential candidates for various biomedical applications including targeted delivery, detection/diagnosis and imaging [2][3]. However, mechanisms by which C225 and its nanoconjugates transport to the cell and molecular machineries involved for intracellular delivery are not well understood. A better understanding of the regulatory components involved in endocytosis of these nanoconjugates will aide us for successful nanodesign to achieve specific intracellular targeting. Exploiting strong affinity of gold nanoparticles (AuNPs) to bind to –SH and –NH2 moieties present in the cysteine and lysine residues of C225, we design two Au-C225 conjugates having variable number of antibody to demonstrate that the mechanism of endocytosis of C225 in PANC-1 cells can be tailored by precise design of the nanoconjugates [4]. Using pharmacological inhibitors (Supplementary Figure 1), genetic approaches and Cdc42 null cells we demonstrate that both C225 and gold-conjugated C225 with complete surface coverage (Au-C225-C; ∼3 C225/particle) requires clustering in the GSL (Glycosphingolipid) domains at the plasma membrane followed by dynamin-2 (dyn-2) dependent caveolar endocytosis. However, partially covered nanoconjugate (Au-C225-P; ∼1 C225/particle) is internalized via dyn-2 independent Cdc42 dependent pinocytosis/phagocytosis that requires actin polymerization. Regulating the endocytosis of cetuximab between caveolar and pinocytic internalization by appropriate nanodesign may be useful to target specific intracellular pathways for better therapeutic intervention with reduced side effects.