Identification, characterization and application of a new peptide against anterior gradient homolog 2 (AGR2)
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Carolina Garri1,*, Shannon Howell3,*, Katrin Tiemann1, Aleczandria Tiffany4, Farzad Jalali-Yazdi4, Mario M. Alba1, Jonathan E. Katz1, Terry T. Takahashi3, Ralf Landgraf5, Mitchell E. Gross1,2, Richard W. Roberts2,3,4 and Kian Kani1,2
1Keck School of Medicine, Lawrence J. Ellison Institute for Transformative Medicine, University of Southern California, Los Angeles, CA, USA
2USC Norris Comprehensive Cancer Center, Los Angeles, CA, USA
3Department of Chemistry, University of Southern California, Los Angeles, CA, USA
4Mork Family Department of Chemical Engineering and Material Science, University of Southern California, Los Angeles, CA, USA
5University of Miami, Miller School of Medicine, Department of Biochemistry and Molecular Biology, Miami, FL, USA
*These authors have contributed equally to this work
Kian Kani, email: [email protected]
Keywords: AGR2; mRNA display; cancer; therapeutic; biomarker
Received: November 11, 2017 Accepted: April 02, 2018 Published: June 08, 2018
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.
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