• Open Access

Enhanced internalization of ErbB2 in SK-BR-3 cells with multivalent forms of an artificial ligand

Authors

  • Arun Vaidyanath,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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  • Toshihiro Hashizume,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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  • Tadahiro Nagaoka,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
    2. Tumour Growth Factor Section, Mammary Biology and Tumorigenesis Laboratory, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
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  • Nao Takeyasu,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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  • Hitomi Satoh,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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  • Ling Chen,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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  • Jiyou Wang,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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  • Tomonari Kasai,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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  • Takayuki Kudoh,

    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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  • Ayano Satoh,

    1. Research Core for Interdisciplinary Sciences, Okayama University, Kita-ku, Okayama, Japan
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  • Li Fu,

    1. Department of Breast Cancer Pathology and Research Laboratory, State Key Laboratory of Breast Cancer Research, Cancer Hospital of Tianjin Medical University, Tianjin, China
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  • Masaharu Seno

    Corresponding author
    1. Laboratory of Nano-Biotechnology, Department of Medical Bioengineering Science, Graduate School of Natural Science and Biotechnology, Okayama University, Kita-ku, Okayama, Japan
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Masaharu SENO, Faculty of Engineering, Okayama University, Room 361, Building ENG-6, 3.1.1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan. Tel.: +81-86-251-8216 Fax: +81-86-251-8216 E-mail: mseno@cc.okayama-u.ac.jp

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.

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