Identification, characterization and application of a new peptide against anterior gradient homolog 2 (AGR2)

  • Oncotarget. 2018 Jun 8;9(44):27363-27379. doi: 10.18632/oncotarget.25221.
Carolina Garri  #  1 ,  Shannon Howell  #  2 ,  Katrin Tiemann  1 ,  Aleczandria Tiffany  3 ,  Farzad Jalali-Yazdi  3 ,  Mario M Alba  1 ,  Jonathan E Katz  1 ,  Terry T Takahashi  2 ,  Ralf Landgraf  4 ,  Mitchell E Gross  1  5 ,  Richard W Roberts  5  2  3 ,  Kian Kani  1  5
Affiliations
  • 1. Keck School of Medicine, Lawrence J. Ellison Institute for Transformative Medicine, University of Southern California, Los Angeles, CA, USA.
  • 2. Department of Chemistry, University of Southern California, Los Angeles, CA, USA.
  • 3. Mork Family Department of Chemical Engineering and Material Science, University of Southern California, Los Angeles, CA, USA.
  • 4. University of Miami, Miller School of Medicine, Department of Biochemistry and Molecular Biology, Miami, FL, USA.
  • 5. USC Norris Comprehensive Cancer Center, Los Angeles, CA, USA.
  • # Contributed equally.
PMID: 29937991 DOI: 10.18632/oncotarget.25221
Abstract

The cancer-associated protein Anterior Gradient 2 (AGR2) has been described, predominantly in adenocarcinomas. Increased levels of extracellular AGR2 (eAGR2) have been correlated with poor prognosis in Cancer patients, making it a potential biomarker. Additionally, neutralizing AGR2 antibodies showed preclinical effectiveness in murine Cancer models suggesting eAGR2 may be a therapeutic target. We set out to identify a peptide by mRNA display that would serve as a theranostic tool targeting AGR2. This method enables the selection of peptides from a complex (>1011) library and incorporates a protease incubation step that filters the selection for serum stable peptides. We performed six successive rounds of enrichment using a 10-amino acid mRNA display library and identified several AGR2 binding peptides. One of these peptides (H10), demonstrated high affinity binding to AGR2 with a binding constant (KD) of 6.4 nM. We developed an AGR2 ELISA with the H10 peptide as the capture reagent. Our H10-based ELISA detected eAGR2 from Cancer cell spent media with a detection limit of (20-50 ng/ml). Furthermore, we investigated the therapeutic utility of H10 and discovered that it inhibited cell viability at IC50 (9-12 μmoles/L) in Cancer cell lines. We also determined that 10 μg/ml of H10 was sufficient to inhibit Cancer cell migration in breast and prostate Cancer cell lines. A control peptide did not show any appreciable activity in these cells. The H10 peptide showed promise as both a novel diagnostic and a potential therapeutic peptide.

Keywords
AGR2; biomarker; cancer; mRNA display; therapeutic.
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