Dendrimer antibody conjugate to target and image HER-2 overexpressing cancer cells

Abstract

// James B. Otis 1 , Hong Zong 1 , Alina Kotylar 1 , Anna Yin 1 , Somnath Bhattacharjee 1 , Han Wang 2 , James R. Baker Jr 1 , Su He Wang 1 1 Department of Internal Medicine, Division of Allergy, Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan, Ann Arbor, Michigan, USA 2 Department of Radiology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shangai, P.R.China Correspondence to: Su He Wang, email: shidasui@med.umich.edu Keywords: anti-HER2-monoclonal antibody, gold nanoparticles, PAMAM dendrimer, imaging agent, targeting Received: November 25, 2015      Accepted: March 31, 2016      Published: April 28, 2016 ABSTRACT Although many breast and lung cancers overexpress human epidermal growth factor receptor-2 (HER-2), no methods currently exist for effective and early detection of HER-2-positive cancers. To address this issue, we designed and synthesized dendrimer-based novel nano-imaging agents that contain gold nanoparticles (AuNPs) and gadolinium (Gd), conjugated with the humanized anti-HER-2 antibody (Herceptin). Generation 5 (G5) polyamidoamine (PAMAM) dendrimers were selected as the backbone for the nano-imaging agents due to their unique size, high ratio of surface functional groups and bio-functionality. We modified G5 PAMAM dendrimer surface with PEG and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelators to encapsulate AuNPs and complex Gd. These dendrimer entrapped AuNPs were further conjugated with Herceptin through copper-catalyzed azide- alkyne click reaction to construct the nano-imaging agent Au-G5-Gd-Herceptin. The targeted nano-imaging agent bound selectively to HER-2 overexpressing cell lines, with subsequent internalization into the cells. More importantly, non-targeted nano-imaging agent neither bound nor internalized into cells overexpressing HER-2. These results suggest that our approach could provide a platform to develop nano-diagnostic agents or nano-therapeutic agents for early detection and treatment of HER-2-positive cancers.