title: Enhanced internalization of ErbB2 in SK-BR-3 cells with multivalent forms of an artificial ligand.
abstract: Targeting and down-regulation of ErbB2, a member of EGF receptor family, is regarded as one of the key aspect for cancer treatment because it is often overexpressed in breast and ovarian cancer cells. Although natural ligands for ErbB2 have not been found, unlike other ErbB receptors, EC-1, a 20-amino acid circular peptide, has been shown to bind to ErbB2 as an artificial ligand. Previously we showed EC-1 peptide did not induce the internalization of ErbB2 in SK-BR-3 cells. In this report, we designed divalent and multivalent forms of EC-1 peptide with the Fc portion of the human IgG and bionanocapsule modified with ZZ-tag on its surface to improve the interaction with ErbB2. These forms showed higher affinity to ErbB2 than that of EC-1 monomer. Furthermore, prominent endosomal accumulation of ErbB2 occurred in SK-BR-3 cells when stimulated with EC-Fc ligand multivalently displayed on the surface of the bionanocapsule, whereas SK-BR-3 cells as themselves displayed stringent mechanism against ErbB2 internalization without stimulation. The multivalent form of EC-1 peptide appeared to internalize ErbB2 more efficiently than divalent form did. This internalization was unaffected by the inhibition of clathrin association, but inhibited when the cholesterol was depleted which explained either caveolar or GPI-AP-early endocytic compartment (GEEC) pathway. Because of the lack of caveolin-1 expression, caveolar machinery may be lost in SK-BR-3 cell line. Therefore, it is suggested that the multivalent form of EC-1 induces the internalization of ErbB2 through the GEEC pathway.
authors.affiliation: Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan.
authors.forename: Arun
authors.initials: A
authors.lastname: Vaidyanath
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Hashizume
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Nagaoka
authors.forename: Nao
authors.initials: N
authors.lastname: Takeyasu
authors.forename: Hitomi
authors.initials: H
authors.lastname: Satoh
authors.forename: Ling
authors.initials: L
authors.lastname: Chen
authors.forename: Jiyou
authors.initials: J
authors.lastname: Wang
authors.forename: Tomonari
authors.initials: T
authors.lastname: Kasai
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kudoh
authors.forename: Ayano
authors.initials: A
authors.lastname: Satoh
authors.forename: Li
authors.initials: L
authors.lastname: Fu
authors.forename: Masaharu
authors.initials: M
authors.lastname: Seno
mesh_terms: D001943:Breast Neoplasms; D051242:Caveolin 1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000172:deficiency; D002966:Clathrin / Q000494:pharmacology; D005260:Female; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism; D007074:Immunoglobulin G; D008024:Ligands; D010051:Ovarian Neoplasms; D010455:Peptides / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D051242:Caveolin 1; D002784:Cholesterol; D002966:Clathrin; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D008024:Ligands; D010455:Peptides; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human