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.

Surface modification of microparticles causes differential uptake responses in normal and tumoral human breast epithelial cells

“…It has been reported that SKBR-3 cells internalize their overexpressed ErbB2 receptors in a clathrin- and caveolin- independent endocytic pathway45. What is more, SKBR-3 cells lack caveolae, and ErbB2 internalization is sensitive to the depletion of cholesterol, which is necessary for most of the clathrin-independent pathways46. In addition, an association between macropinocytosis and tumor progression/metastasis has been reported47.…”

A Kinase Inhibitor Screen Reveals Protein Kinase C-dependent Endocytic Recycling of ErbB2 in Breast Cancer Cells

“…Substantial evidence indicates that overexpressed ErbB2 traffics through the endocytic recycling pathway (15)(16)(17)(18). As endocytic recycling of ErbB2 is thought to critically contribute to its oncogenic signaling (18,80), and enhanced lysosomal degradation of ErbB2 is seen with ErbB2-targeted therapeutics (10,78), a better understanding of the biochemical pathways that regulate ErbB2 recycling is of substantial interest.…”

“…An important determinant of the oncogenicity of ErbB2 is its propensity to avoid lysosomal degradation and to instead traffic via the endocytic recycling pathway (15)(16)(17)(18). Molecular pathways that regulate ErbB2 recycling however remain unexplored.…”

“…Within the ErbB receptor family, endocytic traffic has been most clearly elucidated for EGFR. Ligand-activated EGFR is internalized through clathrin-dependent and multiple clathrin-independent pathways (15)(16)(17)(18). The subsequent endocytic routing of internalized EGFR and other RTKs has emerged as a major determinant of their function.…”

Hyaluronic Acid Mediated Enrichment of CD44 Expressing Glioblastoma Stem Cells in U251MG Xenograft Mouse Model

“…Further the establishment of the model system will be advantageous for the replenishment of CSC, as in long turn in vitro culture system these cells undergo differentiation to normal cancer cells. Enrichment of CD44 expressing cells would be a better platform in the drug targeting experiments for CSCs as we previously successfully showed targeting HER2 breast cancer cells with our bionanocapsule [37] and liposome [38,39] with HER2-binding artificial ligands and such models will provide extensive knowledge in the therapeutic intervention in curbing the cancer growth and metastasis. The advantage of our model involves its cost-effective enrichment of the CD44 expressing glioblastoma cells cells were the up regulation were found to be 2-fold when compared with adherent HA-conditions.…”