title: Controlled internalization of Her-2/ neu receptors by cross-linking for targeted delivery.
abstract: Receptor mediated internalization is a crucial step for targeted intracellular delivery of therapeutic and imaging agents. It was recently demonstrated that trastuzumab, an FDA approved humanized monoclonal antibody against Her-2/ neu tyrosine kinase receptor, did not induce endocytosis of the internalization resistant Her-2/ neu receptor. Here we report that accelerated internalization of trastuzumab can be induced by cross-linking the cell membrane bound antibody-receptor complex with an avidin/streptavidin-biotin system. We demonstrated that internalization was achieved both in vitro and in vivo in Her-2/ neu expressing human breast cancer cell lines (BT-474, SK-BR-3 and AU-565) and that repetitive labeling cycles further amplified the loading of cargo molecules within the targeted cells. No trastuzumab binding and internalization was observed in Her-2/ neu negative MDA-MB-231 cells, whereas weak membrane binding and negligible internalization were detected in MCF-7 cells with low expression level of Her-2/ neu receptor. The method was used to noninvasively image Her-2/ neu receptors in isolated cells and in a preclinical breast cancer model with MRI. The controlled internalization of Her-2/ neu receptors can potentially enhance intracellular delivery of drugs and imaging probes, and improve imaging sensitivity and selectivity as well as therapeutic efficacy, through antibody-directed binding and internalization using a pretargeting approach.
authors: JHU ICMIC Program, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
authors: Wenlian
authors: W
authors: Zhu
authors: Baasil
authors: B
authors: Okollie
authors: Dmitri
authors: D
authors: Artemov
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000493:pharmacokinetics*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001360:Avidin / Q000494:pharmacology*; D019921:Biotinylation; D001943:Breast Neoplasms / Q000473:pathology; D045744:Cell Line, Tumor / Q000378:metabolism / Q000637:transplantation / Q000648:ultrastructure; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D016503:Drug Delivery Systems / Q000379:methods*; D004705:Endocytosis; D005260:Female; D005456:Fluorescent Dyes / Q000032:analysis; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009930:Organic Chemicals / Q000032:analysis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000187:drug effects* / Q000276:immunology; D019809:Streptavidin / Q000494:pharmacology*; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D001360:Avidin; D003432:Cross-Linking Reagents; D005456:Fluorescent Dyes; D009930:Organic Chemicals; D018719:Erb-b2 Receptor Tyrosine Kinases; D019809:Streptavidin; D000068878:Trastuzumab; C417664:Alexa594; C508053:ERBB2 protein, human