Analysis and optimization of interactions between peptides mimicking the GD2 ganglioside and the monoclonal antibody 14G2a
Overexpression of the GD2 ganglioside (GD2) is a hallmark of neuroblastoma. The antigen is used in neuroblastoma diagnosis and to target newly developed therapies to cancer cells. Peptide mimetics are novel approaches in the design of antigens for vaccine development. We previously reported the isol...
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Published in | International journal of molecular medicine Vol. 28; no. 1; pp. 47 - 57 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Greece
D.A. Spandidos
01.07.2011
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Subjects | |
Online Access | Get full text |
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Summary: | Overexpression of the GD2 ganglioside (GD2) is a hallmark of neuroblastoma.
The antigen is used in neuroblastoma diagnosis and to target newly developed therapies
to cancer cells. Peptide mimetics are novel approaches in the design of antigens
for vaccine development. We previously reported the isolation of five GD2-mimicking
peptides from the LX-8 phage display library with the monoclonal antibody (mAb)
14G2a. The goal of our current study was to analyze and optimize the binding of
the peptide mimetics to the mAb 14G2a. Therefore, we performed further experiments
and supported them with molecular modeling to investigate structure-activity relationships
that are the basis for the observed mimicry of GD2 by our peptides. Here, we show
that the peptides have overlapping binding sites on the mAb, 14G2a and restricted
specificity, as they did not crossreact with other ganglioside-specific antibodies
tested. In addition we demonstrate that the phage environment was involved in
the process of selection of our peptides. The AAEGD sequence taken from the viral
major coat protein, p8, and added to the C-termini of the peptides #65, #85 and
#94 significantly improved their binding to the mAb, 14G2a. By application of
analogs with amino acid substitutions and sequence truncations, we elucidated
the structure-activity relationships necessary for the interactions between the
14G2a mAb and the peptide #94 (RCNPNMEPPRCF). We identified amino acids indispensable
for the observed GD2-mimicry by #94 and confirmed a pivotal role of the disulphide
bridge between the cysteine residues of #94 for binding to the mAb 14G2a. More
importantly, we report five new peptides demonstrating a significant improvement
of mAb 14G2a binding. The experimental data were supported and expanded with molecular
modeling tools. Taken together, the experimental results and the in silico data
allowed us to probe in detail the mechanism of the molecular mimicry of GD2 by
the peptides. Additionally, we significantly optimized binding of the leading
peptide sequence #94 to the mAb 14G2a. We can conclude that our findings add to
the knowledge on factors governing selections of peptide mimetics from phage-display
libraries. |
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ISSN: | 1107-3756 1791-244X |
DOI: | 10.3892/ijmm.2011.655 |