"Epitope mapping studies were carried out using an overlapping series of synthetic peptides (CPC Scientific, CA) designed based on the primary sequence of OPN. Peptides corresponding to the region 143-172 of human OPN are listed below [..]"
Abstract
Osteopontin (OPN), also known as SPP1 (secreted phosphoprotein), is an integrin binding glyco-phosphoprotein produced by a variety of tissues. In cancer patients expression of OPN has been associated with poor prognosis in several tumor types including breast, lung, and colorectal cancers. Despite wide expression in tumor cells and stroma, there is limited evidence supporting role of OPN in tumor progression and metastasis. Using phage display technology we identified a high affinity a nti-O PN m onoclonal antibody (hereafter AOM1). The binding site for AOM1 was identified as SVVYGLRSKS sequence which is immediately adjacent to the RGD motif and also spans the thrombin cleavage site of the human OPN. AOM1 efficiently inhibited OPNa binding to recombinant integrin αvβ3 with an IC50 of 65 nM. Due to its unique binding site, AOM1 is capable of inhibiting OPN cleavage by thrombin which has been shown to produce an OPN fragment that is biologically more active than the full length OPN. Screening of human cell lines identified tumor cells with increased expression of OPN receptors (αvβ3 and CD44v6) such as mesothelioma, hepatocellular carcinoma, breast, and non-small cell lung adenocarcinoma (NSCLC). CD44v6 and αvβ3 were also found to be highly enriched in the monocyte, but not lymphocyte, subset of human peripheral blood mononuclear cells (hPBMCs). In vitro, OPNa induced migration of both tumor and hPBMCs in a transwell migration assay. AOM1 significantly blocked cell migration further validating its specificity for the ligand. OPN was found to be enriched in mouse plasma in a number of pre-clinical tumor model of non-small cell lung cancers. To assess the role of OPN in tumor growth and metastasis and to evaluate a potential therapeutic indication for AOM1, we employed a KrasG12D-LSLp53fl/fl subcutaneously implanted in vivo model of NSCLC which possesses a high capacity to metastasize into the lung. Our data indicated that treatment of tumor bearing mice with AOM1 as a single agent or in combination with Carboplatin significantly inhibited growth of large metastatic tumors in the lung further supporting a role for OPN in tumor metastasis and progression.
“Epitope mapping studies were carried out using an overlapping series of synthetic peptides (CPC Scientific, CA) designed based on the primary sequence of OPN. Peptides corresponding to the region 143-172 of human OPN are listed below:
1. 143EVFTPVVPTVDTYDGRGDSVVYGLRSKSKK172
2. 143EVFTPVVPTVDTYDGRGDSVVYGLR167
3. 143EVFTPVVPTVDTYD156
4. 156DGRGDSVVYGLRSKSKK172″
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CPC Scientific at DCAT 2025!
GMP Peptide Manufacturing
What an amazing time we had at DCAT 2025! It was fantastic to meet with colleagues, clients, and friends, and showcase CPC Scientific’s cutting-edge capabilities in synthetic API development and commercial production.
A heartfelt […]
We are excited to share that CPC Scientific Inc. has officially received the Good Manufacturing Practice (GMP) Certificate in accordance with the ISO 22716:2007(E) Cosmetic Guidelines.
This certification highlights our unwavering commitment to delivering the highest quality peptide ingredients for cosmetic use, guaranteeing:
- Superior Quality Control – Striving for excellence in safety, consistency, and purity.
[…]
In Part 1 of our Minimal Protection Group Strategies for SPPS, we discussed methods for eliminating sidechain protection on hydroxy-bearing amino acids such as serine, threonine, tyrosine, and hydroxyproline. By omitting t-butyl protection, we enhanced atom economy and avoided the use of hazardous solvents typically required to remove these protection groups. In Part 2, we present a new case study, expanding our approach to include the unprotected side chains of histidine, tryptophan, and arginine. We demonstrate the synthesis of a Goserelin peptide API impurity, showcasing how a convergent peptide fragment strategy can be used to eliminate the need for TFA and diethyl ether, eliminate side chain protection of Arginine, Histidine, and Tryptophan.
The synthesis of the linear RP-182 analog, bicyclo[6.1.0]non-4-yn-9-ylmethyloxycarbonyl-PEG2-Lys-Phe-Arg-Lys-Ala-Phe-Lys-Arg-Phe-Phe-Lys(azido-PEG)-NH2, was achieved using standard solid-phase peptide synthesis (SPPS) protocols. After cleaving the linear peptide from the resin, macrocyclization was performed in the liquid phase through a strain-promoted click reaction. BCN introduces extra ring strain due to its fused cyclopropane structure. The combined effect of ring strain, the selection of BCN, and copper catalysis significantly increases the macrocyclization efficiency of longer peptides like RP-182.
Nakagawa, Mayumi, Teresa Evans, Milan Bimali, Hannah Coleman, Jasmine Crane, Nadia Darwish, Jennifer L. Faulkner et al. MedRxiv (2025): 2025-01.
The vaccine consisted of four current good manufacturing production-grade synthetic peptides covering the HPV 16 E6 protein [amino acid (aa)1-45, 46-80, 81-115, and 116-158] (CPC Scientific, San Jose, CA [..]
Stapled peptides have emerged as a powerful tool in drug discovery and therapeutic development due to their ability to overcome the limitations associated with traditional peptide drugs, such as poor stability and low cell permeability. By introducing staples into the peptide backbone, researchers can stabilize peptide conformations and enhance their interactions with target proteins, resulting in improved efficacy and specificity. This approach not only addresses the challenges of peptide drug design but also opens new avenues for targeting challenging biomolecular interactions that are difficult to modulate with small molecules or antibodies. The development of stapled peptides has led to significant advancements in targeting protein-protein interactions, addressing previously intractable diseases, and enhancing the precision of therapeutic interventions.
Peptide receptor radionuclide therapy (PRRT) is a targeted therapeutic approach that utilizes peptides to deliver cytotoxic radiation to specific receptors overexpressed on cancer cells. Peptides offer several advantages as therapeutic vectors in PRRT due to their small size, favorable pharmacokinetics, high binding affinity, low immunogenicity and toxicity, and minimal off-target effects. Tumor-targeting peptides conjugated to radionuclide chelates represent a promising class of cancer therapeutics.
Singh, S.S., Calvo, R., Kumari, A., Sable, R.V., Fang, Y., Tao, D., Hu, X., Castle, S.G., Nahar, S., Li, D. and Major, E. Molecular Cancer Therapeutics (2024).
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[..] assembling the peptide on the Rink Amide resin and attaching the PEG azide moiety to the N-terminal Lys, the Dde group was removed as previously shown and coupled to the Fmoc-PEG2-acid. Removal of the Fmoc followed by simultaneously click/coupling to bicyclo[6.1.0]non-4-yn-9-ylmethyl (2,5-dioxopyrrolidin-1-yl) carbonate gave 1c which was deprotected and cleaved from the resin to give 1c.