title: The level of HER2 expression is a predictor of antibody-HER2 trafficking behavior in cancer cells.
abstract: The receptor tyrosine kinase HER2 is known to play a central role in mitogenic signaling, motivating the development of targeted, HER2-specific therapies. However, despite the longstanding use of antibodies to target HER2, controversies remain concerning antibody/HER2 trafficking behavior in cancer cells. Understanding this behavior has direct relevance to the mechanism of action and effective design of such antibodies. In the current study, we analyzed the intracellular dynamics of trastuzumab, a marketed HER2-targeting antibody, in a panel of breast and prostate cancer cell lines that have a wide range of HER2 expression levels. Our results reveal distinct post-endocytic trafficking behavior of antibody-HER2 complexes in cells with different HER2 expression levels. In particular, HER2-overexpressing cells exhibit efficient HER2 recycling and limited reductions in HER2 levels upon antibody treatment, and consequently display a high level of antibody persistence on their plasma membrane. By contrast, in cells with low HER2 expression, trastuzumab treatment results in rapid antibody clearance from the plasma membrane combined with substantial decreases in HER2 levels and undetectable levels of recycling. A cell line with intermediate levels of HER2 expression exhibits both antibody recycling and clearance from the cell surface. Significantly, these analyses demonstrate that HER2 expression levels, rather than cell origin (breast or prostate), is a determinant of subcellular trafficking properties. Such studies have relevance to optimizing the design of antibodies to target HER2.
authors.affiliation: a Department of Immunology ; University of Texas Southwestern Medical Center ; Dallas , TX USA.
authors.forename: Sripad
authors.initials: S
authors.lastname: Ram
authors.forename: Dongyoung
authors.initials: D
authors.lastname: Kim
authors.forename: Raimund J
authors.initials: RJ
authors.lastname: Ober
authors.forename: E Sally
authors.initials: ES
authors.lastname: Ward
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000276:immunology* / Q000378:metabolism; D004705:Endocytosis / Q000276:immunology; D006801:Humans; D042541:Intracellular Space / Q000276:immunology / Q000378:metabolism; D008856:Microscopy, Fluorescence; D018448:Models, Immunological; D009369:Neoplasms / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D011485:Protein Binding / Q000276:immunology; D021381:Protein Transport / Q000187:drug effects / Q000276:immunology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000378:metabolism; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C485206:pertuzumab
keywords: ADCC, antibody dependent cell-mediated cytotoxicity; ADCP, antibody dependent cell-mediated phagocytosis; ADCs, Antibody drug conjugates; HER2 degradation; intracellular trafficking