Identification of a Glypican-3 Binding Peptide From a Phage-Displayed Peptide Library for PET Imaging of Hepatocellular Carcinoma.
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ABSTRACT:
SUBMITTER: Yan J
PROVIDER: S-EPMC8212053 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:UnlabelledHepatocellular carcinoma (HCC) is a devastating malignancy in which imperfect imaging plays a primary role in diagnosis. Glypican-3 (GPC3) is an HCC-specific cell surface proteoglycan overexpressed in most HCCs. This paper presents the use of (89)Zr-conjugated monoclonal antibody against GPC3 ((89)Zr-αGPC3) for intrahepatic tumor localization using PET.MethodsPolymerase chain reaction confirmed relative GPC3 expression in cell lines. In vitro binding, in vivo biodistribution, and small-animal PET studies were performed on GPC3-expressing HepG2 and non-GPC3-expressing HLF and RH7777 cells and orthotopic xenografts.Results(89)Zr-αGPC3 demonstrated antibody-dependent, antigen-specific tumor binding. HepG2 liver tumors exhibited high peak uptake (836.6 ± 86.6 percentage injected dose [%ID]/g) compared with background liver (27.5 ± 1.6 %ID/g). Tumor-to-liver contrast ratio was high and peaked at 32.5. The smallest HepG2 tumor (<1 mm) showed lower peak uptake (42.5 ± 6.4 %ID/g) and tumor-to-liver contrast (1.57) but was still clearly visible on PET. Day 7 tissue activity was still substantial in HepG2 tumors (466.4 ± 87.6 %ID/g) compared with control RH7777 tumors (3.9 ± 1.3 %ID/g, P < 0.01), indicating antigen specificity by (89)Zr-αGPC3. HepG2 tumor treated with unlabeled αGPC3 or heat-denatured (89)Zr-αGPC3 demonstrated tumor activity (2.1 %ID/g) comparable to that of control xenografts, confirming antibody dependency.ConclusionThis study demonstrated the feasibility of using (89)Zr-αGPC3 to image HCC in the liver, as well as the qualitative determination of GPC3 expression via small-animal PET. The ability to clarify the identity of small liver lesions with an HCC-specific PET probe would provide clinicians with vital information that could significantly alter patient management, warranting further investigation for clinical translation.
| S-EPMC4116087 | biostudies-literature
Project description:Superior to linear peptides in biological activities, cyclic peptides are considered to have great potential as therapeutic agents. To identify cyclic-peptide ligands for therapeutic targets, phage-displayed peptide libraries in which cyclization is achieved by the covalent conjugation of cysteines have been widely used. To resolve drawbacks related to cysteine conjugation, we have invented a phage-display technique in which its displayed peptides are cyclized through a proximity-driven Michael addition reaction between a cysteine and an amber-codon-encoded N? -acryloyl-lysine (AcrK). Using a randomized 6-mer library in which peptides were cyclized at two ends through a cysteine-AcrK linker, we demonstrated the successful selection of potent ligands for TEV protease and HDAC8. All selected cyclic peptide ligands showed 4- to 6-fold stronger affinity to their protein targets than their linear counterparts. We believe this approach will find broad applications in drug discovery.
| S-EPMC6803038 | biostudies-literature
Project description:BackgroundNew molecular probes are essential for early colon cancer diagnosis. A phage-display screening was performed to select novel binding peptides for early colon cancer imaging detection.MethodsA human colon cancer cell line (COLO320HSR) and a normal human intestinal epithelial cell line (NCM460) were used for subtractive screening with a phage peptide library. The positive peptides were identified, and their binding capacities were confirmed by confocal immunofluorescence both in human colon cancer cells and in biopsy specimens. The sequences were further analysed for homology and the existing mimotopes by the BLAST algorithm and the MimoDB database.ResultsA peptide termed as CBP-DWS, which was demonstrated to be capable of binding to a panel of human colon cancer cell lines and tissues, was identified; it had virtually no binding to normal human intestinal epithelial cell line NCM460 and normal surrounding colon tissues. Bioinformatics analyses suggest that CBP-DWS targets human Glypican-3, which may be involved in important cellular functions in multiple cancer types.ConclusionsThese studies suggest that the selected peptide CBP-DWS may be a candidate to serve as a novel probe for colon cancer imaging.
| S-EPMC5765222 | biostudies-literature
Project description:Amino acid sequence diversity is introduced into a phage-displayed peptide library by randomizing library oligonucleotide DNA. We recently evaluated the diversity of peptide libraries displayed on T7 lytic phage and M13 filamentous phage and showed that T7 phage can display a more diverse amino acid sequence repertoire due to differing processes of viral morphogenesis.In this study, we evaluated and compared the diversity of a 12-mer T7 phage-displayed peptide library randomized using codon-corrected trinucleotide cassettes with a T7 and an M13 12-mer phage-displayed peptide library constructed using the degenerate codon randomization method.We herein demonstrate that the combination of trinucleotide cassette amino acid codon randomization and T7 phage display construction methods resulted in a significant enhancement to the functional diversity of a 12-mer peptide library. This novel library exhibited superior amino acid uniformity and order-of-magnitude increases in amino acid sequence diversity as compared to degenerate codon randomized peptide libraries. Comparative analyses of the biophysical characteristics of the 12-mer peptide libraries revealed the trinucleotide cassette-randomized library to be a unique resource.The combination of T7 phage display and trinucleotide cassette randomization resulted in a novel resource for the potential isolation of binding peptides for new and previously studied molecular targets.
| S-EPMC2174457 | biostudies-other
Project description:Peptides with specific affinities for various materials have been identified in the past three decades and utilized in materials science and engineering. A peptide's capability to specifically interact with materials is not naturally derived but screened from a biologically constructed peptide library displayed on phages or cells. To date, due to limitations in the screening procedure, the function of screened peptides has been primarily limited to the affinity for target materials. Herein, we demonstrated the screening of surfactant-like peptides from a phage-displayed peptide library. A screened phage clone displaying a peptide showed high activity for accumulating at emulsion surfaces with certain assembled structures, resulting in stable emulsions. The surface tension for the solution of the chemically synthesized peptide decreased with increasing peptide concentration, demonstrating certain surface activity, which corresponded to the ability to decrease the surface tension of liquids (e.g., water), owing to the accumulation of molecules at the air-liquid or liquid-liquid interface. Peptides with a randomized sequence did not lower the surface tension, indicating the essential role of amino acid sequences in surface activity. Our strategy for identifying novel functional peptides from a phage-displayed peptide library can be used to expand the applicability of peptidyl materials and biosurfactants.
| S-EPMC7765448 | biostudies-literature
Project description:BackgroundCoronavirus disease 19 (COVID-19) first appeared in the city of Wuhan, in the Hubei province of China. Since its emergence, the COVID-19-causing virus, SARS-CoV-2, has been rapidly transmitted around the globe, overwhelming the medical care systems in many countries and leading to more than 3.3 million deaths. Identification of immunological epitopes on the virus would be highly useful for the development of diagnostic tools and vaccines that will be critical to limiting further spread of COVID-19.MethodsTo find disease-specific B-cell epitopes that correspond to or mimic natural epitopes, we used phage display technology to determine the targets of specific antibodies present in the sera of immune-responsive COVID-19 patients. Enzyme-linked immunosorbent assays were further applied to assess competitive antibody binding and serological detection. VaxiJen, BepiPred-2.0 and DiscoTope 2.0 were utilized for B-cell epitope prediction. PyMOL was used for protein structural analysis.Results36 enriched peptides were identified by biopanning with antibodies from two COVID-19 patients; the peptides 4 motifs with consensus residues corresponding to two potential B-cell epitopes on SARS-CoV-2 viral proteins. The putative epitopes and hit peptides were then synthesized for validation by competitive antibody binding and serological detection.ConclusionsThe identified B-cell epitopes on SARS-CoV-2 may aid investigations into COVID-19 pathogenesis and facilitate the development of epitope-based serological diagnostics and vaccines.
| S-EPMC8182997 | biostudies-literature
Project description:A stapled α-helix peptide library was designed and constructed using a chemically modified phage display system for screening stapled-peptide ligands against target proteins. The α-helix peptide library, with two cysteine residues on the opposite side of the randomized face, was modified with a rigid hydrocarbon staple linker on a phage. The stapled α-helix peptide phage library was screened against galectin-3 (Gal-3), a cancer-related galactose-binding protein. The obtained stapled peptides showed a high binding affinity (K d = 0.45 μM) despite being nonsugar ligands. The stapled modification played important roles in stabilizing the α-helical structure that contributed to the high binding affinity to Gal-3. In addition, the best stapled peptide ligands showed specific binding to Gal-3 among various carbohydrate-binding proteins. Thus, the designed α-helix peptide phage library with a constrained structure by the staple linker will advance the discovery of peptide ligands with improved specificity and affinity.
| S-EPMC7097893 | biostudies-literature
Project description:PurposeHepatocellular carcinoma (HCC) remains one of the most challenging diseases worldwide. Glypican-3 (GPC-3) is a cell surface proteoglycan that is overexpressed on the membrane of HCC cells. The purpose of this study was to develop a target-specific radiofluorinated peptide for positron emission tomography (PET) imaging of GPC3 expression in hepatocellular carcinoma.ProceduresNew GPC3-binding peptides (GP2076 and GP2633) were radiolabeled with F-18 using Al[18F]F labeling approach, and the resulting PET probes were subsequently subject to biological evaluations. A highly hydrophilic linker was incorporated into GP2633 with an aim of reducing the probe uptake in liver and increasing tumor-to-liver (T/L) contrast. Both GP2076 and GP2633 were radiolabeled using Al[18F]F chelation approach. The binding affinity, octanol/water partition coefficient, cellular uptake and efflux, and stability of both F-18 labeled peptides were tested. Tumor targeting efficacy and biodistribution of Al[18F]F-GP2076 and Al[18F]F-GP2633 were determined by PET imaging in HCC-bearing mice. Immunohistochemistry analyses were performed to compare the findings from PET scans.ResultsAl[18F]F-GP2076 and Al[18F]F-GP2633 were rapidly radiosynthesized within 20 min in excellent radiochemical purity (>?97 %). Al[18F]F-GP2633 was determined to be more hydrophilic than Al[18F]F-GP2076 in terms of octanol/water partition coefficient. Both Al[18F]F-GP2076 and Al[18F]F-GP2633 demonstrated good in vitro and in vivo stability and binding specificity to GPC3-positive HepG2 cells. For PET imaging, Al[18F]F-GP2633 exhibited enhanced uptake in HepG2 tumor (%ID/g 3.37?±?0.35 vs. 2.13?±?0.55, P?=?0.031) and reduced accumulation in liver (%ID/g 1.70?±?0.26 vs. 3.70?±?0.98, P?=?0.027) at 60 min post-injection (pi) as compared to Al[18F]F-GP2076, resulting in significantly improved tumor-to-liver (T/L) contrast (ratio 2.00?±?0.18 vs. 0.59?±?0.14, P?=?0.0004). Higher uptake of Al[18F]F-GP2633 in GPC3-positive HepG2 tumor was observed as compared to GPC3-negative McA-RH7777 tumor (%ID/g 3.37?±?0.35 vs. 1.64?±?0.03, P?=?0.001) at 60 min pi, confirming GPC3-specific accumulation of Al[18F]F-GP2633 in HepG2 tumor.ConclusionThe results demonstrated that Al[18F]F-GP2633 is a promising probe for PET imaging of GPC3 expression in HCC. Convenient preparation, excellent GPC3 specificity in HCC, and favorable excretion profile of Al[18F]F-GP2633 warrant further investigation for clinical translation. PET imaging with a GPC3-specific probe would provide clinicians with vital diagnostic information that could have a significant impact on the management of HCC patients.
| S-EPMC7007182 | biostudies-literature
Project description:A promising emerging area for the treatment of obesity and diabetes is combinatorial hormone therapy, where single-molecule peptides are rationally designed to integrate the complementary actions of multiple endogenous metabolically-related hormones. We describe here a proof-of-concept study on developing unimolecular polypharmacy agents through the use of selection methods based on phage-displayed peptide libraries (PDL). Co-agonists of the glucagon (GCG) and GLP-1 receptors were identified from a PDL sequentially selected on GCGR- and GLP1R-overexpressing cells. After two or three rounds of selection, 7.5% of randomly picked clones were GLP1R/GCGR co-agonists, and a further 1.53% were agonists of a single receptor. The phages were sequenced and 35 corresponding peptides were synthesized. 18 peptides were potent co-agonists, 8 of whom showed EC50???30 pM on each receptor, comparable to the best rationally designed co-agonists reported in the literature. Based on literature examples, two sequences were engineered to stabilize against dipeptidyl peptidase IV cleavage and prolong the in vivo half-life: the engineered peptides were comparably potent to the parent peptides on both receptors, highlighting the potential use of phage-derived peptides as therapeutic agents. The strategy described here appears of general value for the discovery of optimized polypharmacology paradigms across several metabolically-related hormones.
| S-EPMC5766609 | biostudies-literature
Project description:UnlabelledHepatocellular carcinoma (HCC) is an increasingly lethal malignancy for which management is critically dependent on accurate imaging. Glypican-3 (GPC3) is a cell surface receptor overexpressed in most HCCs and provides a unique target for molecular diagnostics. The use of monoclonal antibodies (mAbs) that target GPC3 (αGPC3) in PET imaging has shown promise but comes with inherent limitations associated with mAbs such as long circulation times. This study used (89)Zr-conjugated F(ab')2 fragments directed against GPC3 ((89)Zr-αGPC3-F(ab')2) to evaluate the feasibility of the fragments as a diagnostic immuno-PET imaging probe.MethodsImmobilized ficin was used to digest αGPC3, creating αGPC3-F(ab')2 fragments subsequently conjugated to (89)Zr. In vivo biodistribution and PET studies were performed on GPC3-expressing HepG2 and GPC3-nonexpressing RH7777 orthotopic xenografts.ResultsReliable αGPC3-F(ab')2 production via immobilized ficin digestion was verified by high-performance liquid chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. (89)Zr-αGPC3-F(ab')2 demonstrated F(ab')2-dependent, antigen-specific cell binding. HepG2 tumor uptake was higher than any other tissue, peaking at 100 ± 21 percentage injected dose per gram (%ID/g) 24 h after injection, a value 33- to 38-fold higher than GPC3-nonexpressing RH7777 tumors. The blood half-life of the (89)Zr-αGPC3-F(ab')2 conjugate was approximately 11 h, compared with approximately 115 h for historic mAb controls. This shorter half-life enabled clear tumor visualization on PET 4 h after administration, with a resultant peak tumor-to-liver contrast ratio of 23.3. Blocking antigen-expressing tumors with an excess of nonradiolabeled αGPC3 resulted in decreased tumor uptake similar to native liver. The kidneys exhibited high tissue uptake, peaking at 24 h with 83 ± 12 %ID/g. HepG2 tumors ranging from 1.5 to 7 mm were clearly visible on PET, whereas larger RH7777 tumors displayed signal lower than background liver tissue.ConclusionThis study demonstrates the feasibility of using (89)Zr-αGPC3-F(ab')2 for intrahepatic tumor localization with small-animal PET. Faster blood clearance and lower background liver uptake enable excellent signal-to-noise ratios at early time points. Increased renal uptake is similar to that as has been seen with clinical radioactive peptide imaging. (89)Zr-αGPC3-F(ab')2 addresses some of the shortcomings of whole-antibody immuno-PET probes. Further optimization is warranted to maximize probe sensitivity and specificity in the process of clinical translation.
| S-EPMC4259878 | biostudies-literature