Phage-displayed Random Peptide Library Research Articles

Selection of affinity peptides for the purification potential of porcine circovirus type 2 (PCV2) Cap virus-like particles (VLPs)

In this study, we describe the use of a M13 phage-displayed random peptide library for screening novel peptide motifs that specifically recognize recombinant PCV2 Cap protein for the first time.

Generation of a novel artificial TrkB agonist, BM17d99, using T7 phage-displayed random peptide libraries

Tropomyosin receptor kinase B (TrkB) is a known receptor of brain-derived neurotrophic factor (BDNF). Because it plays a critical role in the regulation of neuronal development, maturation, survival, etc., TrkB is a good target for drugs against central nervous system diseases. In this study, we aimed to generate peptidic TrkB agonists by applying random peptide phage display technology. After the phage panning against recombinant Fc-fused TrkB (TrkB-Fc), agonistic phages were directly screened against TrkB-expressing HEK293 cells. Through subsequent screening of the first-hit BM17 peptide-derived focus library, we successfully obtained the BM17d99 peptide, which had no sequence similarity with BDNF but had TrkB-binding capacity. We then synthesized a dimeric BM17d99 analog peptide that could phosphorylate or activate TrkB by facilitating receptor homodimerization. Treatment of TrkB-expressing HEK293 cells with the dimeric BM17d99 analog peptide significantly induced the phosphorylation of TrkB, suggesting that homodimerization of TrkB was enhanced by the dimeric peptide. This report demonstrates that our approach is useful for the generation of artificial peptidic agonists of cell surface receptors.

Epitope Mapping of Mono- and Polyclonal Antibodies by Screening Phage-displayed Random Peptide Libraries.

Detailed knowledge of antigenic determinants is crucial when characterizing therapeutic and diagnostic antibodies, assessing vaccine effectiveness and developing epitope-based vaccines. Most epitope mapping approaches are labor intensive and costly. In this study, we evaluated panning of phage-displayed random peptide libraries against antibodies as a tool for cognate epitope identification. We used six antibodies directed to three model protein antigens as targets to show that the approach is applicable to both mono- and polyclonal antibodies. The technique is well-suited especially for identification of linear epitopes. Mapping of conformational epitopes is more challenging, tends to be more subjective and requires use of computational tools. Nevertheless, when combined with functional data such as structure-activity relationship of antigen muteins, one can make reliable conformational epitope predictions based on phage display experiment data. As the described approach is fast and relatively inexpensive, we suggest it is employed early in antibody characterization and later validated by complementary methods.

Development and comparative study of chemosynthesized antigen and mimotope-based immunoassays for class-specific analysis of O,O-dimethyl organophosphorus pesticides.

The multi-residue determination of organophosphorus pesticides (OPs) is an important task due to the wide application and high toxicity of OPs. However, there is no promising immunoassay to monitor the multi-residue of O,O-dimethyl OPs. In this study, a monoclonal antibody (mAb) against a generic hapten of O,O-dimethyl OPs (O,O-dimethyl O-(3-carboxyphenyl)phosphorothioate) was prepared. To develop an effective class-specific immunoassay, two strategies were performed to select the appropriate coating antigen or competing antigen. On the one hand, a total of 20 haptens were chemosynthesized, attached to ovalbumin for use as coating antigen candidates, and selected by direct competitive ELISA (dcELISA). As a second strategy, mimotopes of the mAb were selected from a random phage-display peptide library by panning, and the optimum mimotope was expressed as a fusion protein and biotinylated in vitro. Based on the selected chemosynthesized coating antigen and the biotinylated mimotope fusion protein, two sensitive broad-specificity dcELISAs were developed. The sensitivity, selectivity and practicability of the two immunoassays were compared. The results demonstrated that both methods showed similar selectivity and sensitivity and were reliable for O,O-dimethyl OP residues screening. However, the screening operation of mimotopes was much simpler and safer compared to the preparation of chemosynthesized coating antigens.

Identification of Novel Short BaTiO3-Binding/Nucleating Peptides for Phage-Templated in Situ Synthesis of BaTiO3 Polycrystalline Nanowires at Room Temperature.

Ferroelectric materials, such as tetragonal barium titanate (BaTiO3), have been widely used in a variety of areas including bioimaging, biosensing, and high power switching devices. However, conventional methods for the synthesis of tetragonal phase BaTiO3 usually require toxic organic reagents and high temperature treatments, and are thus not environment-friendly and energy-efficient. Here, we took advantage of the phage display technique to develop a novel strategy for the synthesis of BaTiO3 nanowires. We identified a short BaTiO3-binding/nucleating peptide, CRGATPMSC (named RS), from a phage-displayed random peptide library by biopanning technique and then genetically fused the peptide to the major coat protein (pVIII) of filamentous M13 phages to form the pVIII-RS phages. We found that the resultant phages could not only bind with the presynthesized BaTiO3 crystals but also induce the nucleation of uniform tetragonal BaTiO3 nanocrystals at room temperature and without the use of toxic reagents to form one-dimensional polycrystalline BaTiO3 nanowires. This approach enables the green synthesis of BaTiO3 polycrystalline nanowires with potential applications in bioimaging and biosensing fields.

Abstract 3908: A multifunctional peptide for targeted imaging, localization of transformed cell and chemotherapy for nasopharyngeal carcinoma and other cancers

Abstract Introduction: In treating cancer with chemotherapy, the ultimate goal is to deliver sufficient amounts of the drug to tumor cells while minimizing the damage of normal tissue. To achieve this purpose, using a phage-displayed random peptide library to screen the nasopharyngeal carcinoma (NPC)-TW01 cell line, we identified a specific peptide (L-peptide), which binds specifically to NPC tumor cells but not normal cells. To investigate whether this L- peptide can also bind to other cancer cell lines, be used for cancer tissue binding, targeted imaging and chemotherapy, we have performed this experiment. Methods: A fluorescein-labelled L-peptide was used to perform FACScan for 7 cancer cell lines. The L-peptide was linked to dextran coated iron oxide (L-P-Fe3O4) nanoparticles and a biotin labeled modified L-peptide (biotin-mL-P) were also used to localize L-peptide targeted protein (X-protein) in NPC and breast cancer surgical specimens. This conjugate was also injected intravenously to SCID mice bearing NPC and breast cancer xenografts for magnetic resonance imaging (MRI) analysis. Furthermore, L-peptide-linked liposomal doxorubicin (L-P-Lipo-Dox) was used to observe the efficacy of peptide-targeted chemotherapy in both cancers. Results and Conclusions: FACscan revealed specific binding of L-peptide to NPC, breast cancer, lung cancer, and neuroblastoma. The X-protein in both cancer specimens localized by biotin-mL-P was seen in many NPC and breast cancer tumor cells with some unstained tumor cells, but not or very weak in normal tissue; the X-protein in formalin-fixed paraffin-embedded section could be localized by L-P-Fe3O4 histochemistry in both cancer specimens. MRI analysis of both cancer xenograft bearing mice after injection of L-P-Fe3O4 revealed significant change in the MR signal intensity. A high efficacy of L-P-Lipo-Dox treatment for both cancers with minimal adverse effect was obtained. This multifunctional L-peptide seems able to be used for localization of its binding protein in each cancer cell type, molecular MRI analysis and targeted chemotherapy with minimal adverse effect in different cancer types. Citation Format: Chin-Tarng Lin, Jong-Kai Hsiao, Hon-Man Liu, Hang-Chung Wu, Alice Yu. A multifunctional peptide for targeted imaging, localization of transformed cell and chemotherapy for nasopharyngeal carcinoma and other cancers. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3908.

Dengue Virus Nonstructural Protein 1-Induced Antibodies Cross-React with Human Plasminogen and Enhance Its Activation.

Dengue virus (DENV) infection is the most common mosquito-borne viral disease, and it can cause life-threatening dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Abnormal activation of the coagulation and fibrinolysis system is one of the hallmarks of DHF/DSS. However, the mechanism underlying hemorrhage in DHF/DSS remains elusive. In previous studies, plasminogen (Plg) cross-reactive Abs, which can recognize DENV nonstructural protein (NS) 1, have been found in dengue patients. However, it is unclear whether these Abs are indeed induced by DENV NS1. Thus, we immunized mice with recombinant NS1 from both bacteria and drosophila to determine whether NS1 can induce Plg cross-reactive Abs. The results from the NS1-immunized mouse sera indicated that NS1 immunization induced Abs that could cross-react with Plg. To study the effects of these NS1-induced Plg cross-reactive Abs on fibrinolysis, we isolated several Plg cross-reactive anti-NS1 mAbs from these mice and found that some of them could enhance Plg activation. In addition, epitope mapping with a phage-displayed random peptide library revealed that one of these mAbs (2A5) could recognize NS1 C-terminal residues 305-311, which share sequence homology with Plg residues 590-597. A synthetic peptide of NS1 residues 305-311 could inhibit the binding of both 2A5 and its Fab to Plg and its enhanced activation. Thus, our results suggest that DENV NS1 can induce Plg cross-reactive Abs through molecular mimicry, which can enhance Plg activation and may contribute to the pathogenesis of DHF/DSS.

Advancement and applications of peptide phage display technology in biomedical science.

Combinatorial phage library is a powerful research tool for high-throughput screening of protein interactions. Of all available molecular display techniques, phage display has proven to be the most popular approach. Screening phage-displayed random peptide libraries is an effective means of identifying peptides that can bind target molecules and regulate their function. Phage-displayed peptide libraries can be used for (i) B-cell and T-cell epitope mapping, (ii) selection of bioactive peptides bound to receptors or proteins, disease-specific antigen mimics, peptides bound to non-protein targets, cell-specific peptides, or organ-specific peptides, and (iii) development of peptide-mediated drug delivery systems and other applications. Targeting peptides identified using phage display technology may be useful for basic research and translational medicine. In this review article, we summarize the latest technological advancements in the application of phage-displayed peptide libraries to applied biomedical sciences.

Screening and identification of immunoactive peptide mimotopes for the enhanced serodiagnosis of tuberculosis.

Although serological detection is a practical strategy for early detection and diagnosis of tuberculosis (TB), inconsistent and imprecise estimates of sensitivity and specificity block its development and application for clinic. New or alternative serological antigens with improved accuracy are urgently needed. A phage-displayed random peptide library was employed to screen for immunoactive peptides using specific immunoglobulin G (IgG) of TB patients as target molecules. With two screening strategies, 20 single phages displaying different sequences were obtained and no sequence homology was found among these phages. From the results of phage-ELISA, H12, TB6, TB15, and TB18 phages showed higher affinity to IgGs from TB patients(S/N ≥2.1) and were identified as the positive clones. Significant differences in the detection values of sera from 47 TB patients and 37 healthy individuals were found for these four phage clones. According to the reactivity of 284 human sera to synthetic H12, TB6, TB15, and TB18 peptides as determined by ELISA, TB15 showed significantly higher areas under the curve (AUC) and sensitivity than other peptides, providing a lead molecule for the development of new serology diagnostic strategies for TB.

Exploration of Peptide Inhibitors of Human Squalene Synthase through Molecular Modeling and Phage Display Technique.

Many studies have demonstrated the role of elevated levels of serum cholesterol in the pathogenesis of atherosclerosis and coronary heart disease. Various drugs targeting the key enzymes involved in the cholesterol biosynthesis pathway have been investigated for the treatment of hypercholesterolemia. Human squalene synthase has been one of the most important targets for therapeutic intervention. In the present study, we used the recombinant human squalene synthase as the lure for screening the peptide inhibitors from phage-displayed random peptide library. The tightly bound phages and their derived peptides were further evaluated based on their potential binding capabilities, molecular modeling characteristics and predicted absorption, distribution, metabolism, excretion, toxicity (ADMET) properties. Several hexa-peptides and tetra-peptides were finally synthesized to assay their inhibitory effects toward the recombinant human squalene synthase. The results demonstrated that the hexa-peptide FTACNW and tetra-peptide VACL can inhibit human squalene synthase effectively (with IC50 values near 100μM) and may have potential to develop further as future hypocholesterolemia agents.

Identification of a Conserved Linear B-Cell Epitope of Streptococcus dysgalactiae GapC Protein by Screening Phage-Displayed Random Peptide Library.

The GapC of Streptococcus dysgalactiae (S. dysgalactiae) is a highly conserved surface protein that can induce protective humoral immune response in animals. However, B-cell epitopes on the S. dysgalactiae GapC have not been well identified. In this study, a monoclonal antibody (mAb5B7) against the GapC1-150 protein was prepared. After passive transfer, mAb5B7 could partially protect mice against S. dysgalactiae infection. Eleven positive phage clones recognized by mAb5B7 were identified by screening phage-displayed random 12-peptide library, most of which matched the consensus motif DTTQGRFD. The motif sequence exactly matches amino acids 48-55 of the S. dysgalactiae GapC protein. In addition, the motif 48DTTQGRFD55 shows high homology among various streptococcus species. Site-directed mutagenic analysis further confirmed that residues D48, T50, Q51, G52 and F54 formed the core motif of 48DTTQGRFD55. This motif was the minimal determinant of the B-cell epitope recognized by the mAb5B7. As expected, epitope-peptide evoked protective immune response against S. dysgalactiae infection in immunized mice. Taken together, this identified conserved B-cell epitope within S. dysgalactiae GapC could provide very valuable insights for vaccine design against S. dysgalactiae infection.

Identification of a conserved B-cell epitope on the GapC protein of Streptococcus dysgalactiae

Streptococcus dysgalactiae (S. dysgalactia) GapC is a highly conserved surface dehydrogenase among the streptococcus spp., which is responsible for inducing protective antibody immune responses in animals. However, the B-cell epitope of S. dysgalactia GapC have not been well characterized. In this study, a monoclonal antibody 1F2 (mAb1F2) against S. dysgalactiae GapC was generated by the hybridoma technique and used to screen a phage-displayed 12-mer random peptide library (Ph.D.-12) for mapping the linear B-cell epitope. The mAb1F2 recognized phages displaying peptides with the consensus motif TRINDLT. Amino acid sequence of the motif exactly matched 30TRINDLT36 of the S. dysgalactia GapC. Subsequently, site-directed mutagenic analysis further demonstrated that residues R31, I32, N33, D34 and L35 formed the core of 30TRINDLT36, and this core motif was the minimal determinant of the B-cell epitope recognized by the mAb1F2. The epitope 30TRINDLT36 showed high homology among different streptococcus species. Overall, our findings characterized a conserved B-cell epitope, which will be useful for the further study of epitope-based vaccines.

Non-ionic detergents facilitate non-specific binding of M13 bacteriophage to polystyrene surfaces

Phage-displayed random peptide libraries are widely used for identifying peptide interactions with proteins and other substrates. Selection of peptide ligands involves iterative rounds of affinity enrichment. The binding properties of the selected phage clones are routinely tested using immunoassay after propagation to high titre in a bacterial host and precipitation using polyethylene glycol (PEG) and high salt concentration. These immunoassays can suffer from low sensitivity and high background signals. Polysorbate 20 (Tween® 20) is a non-ionic detergent commonly used in immunoassay washing buffers to reduce non-specific binding, and is also used as a blocking reagent. We have observed that Tween 20 enhances non-specific M13 library phage binding in a peptide-independent manner. Other non-ionic detergents were also found to promote significant, dose-dependent non-specific phage binding in ELISA. This effect was not observed for assays using phage concentrated by ultracentrifugation, suggesting that interactions occur between detergents and the PEG-precipitated phage, irrespective of the displayed peptide motif. This artefact may impact on successful affinity selection of peptides from phage-display libraries. We propose alternative methods for screening phage libraries for identifying binding interactions with target ligands.

Identification of high-affinity VEGFR3-binding peptides through a phage-displayed random peptide library.

ObjectiveVascular endothelial growth factor (VEGF) interaction with its receptor, VEGFR-3/Flt-4, regulates lymphangiogenesis. VEGFR-3/Flt-4 expression in cancer cells has been correlated with clinical stage, lymph node metastasis, and lymphatic invasion. The objective of this study is to identify a VEGFR-3/Flt-4-interacting peptide that could be used to inhibit VEGFR-3 for ovarian cancer therapy.MethodsThe extracellular fragment of recombinant human VEGFR-3/Flt-4 (rhVEGFR-3/Flt-4) fused with coat protein pIII was screened against a phage-displayed random peptide library. Using affinity enrichment and enzyme-linked immunosorbent assay (ELISA) screening, positive clones of phages were amplified. Three phage clones were selected after four rounds of biopanning, and the specific binding of the peptides to rhVEGFR-3 was detected by ELISA and compared with that of VEGF-D. Immunohistochemistry and immunofluorescence analyses of ovarian cancer tissue sections was undertaken to demonstrate the specificity of the peptides.ResultsAfter four rounds of biopanning, ELISA confirmed the specificity of the enriched bound phage clones for rhVEGFR-3. Sequencing and translation identified three different peptides. Non-competitive ELISA revealed that peptides I, II, and III had binding affinities for VEGFR-3 with Kaff (affinity constant) of 16.4±8.6 µg/mL (n=3), 9.2±2.1 µg/mL (n=3), and 174.8±31.1 µg/mL (n=3), respectively. In ovarian carcinoma tissue sections, peptide III (WHWLPNLRHYAS), which had the greatest binding affinity, also co-localized with VEGFR-3 in endothelial cells lining lymphatic vessels; its labeling of ovarian tumors in vivo was also confirmed.ConclusionThese finding showed that peptide III has high specificity and activity and, therefore, may represent a potential therapeutic approach to target VEGF-VEGFR-3 signaling for the treatment or diagnosis of ovarian cancer.

Abstract A47: IL-4 receptor-targeted delivery of liposomal doxorubicin and siRNA to tumor

Abstract Targeted delivery of imaging agents and therapeutics to tumors would provide early detection and increased therapeutic efficacy against cancer. Using phage displayed-random peptide libraries, we have identified IL4RPep-1 (IL-4 receptor-binding peptide-1), CRKRLDRNC, that binds to IL-4 receptor (IL4R). IL4R is over-expressed on many types of cancer cells including lung cancer and breast cancer. Peptides have smaller size and in turn may exert better tissue penetration than bulky antibodies. IL4RPep-1 bound to H226 lung tumor cells that over-express IL4R, while little binding was observed in H460 lung tumor cells that express IL4R at low levels. When injected intravenously into nude mice bearing a subcutaneous H226 tumor, Cy7.5 near-infrared fluorescence dye-conjugated IL4RPep-1 selectively homed to tumor. IL4RPep-1-labeled liposomes containing doxorubicin showed more efficient anti-tumor growth activity than untargeted liposomes. In addition, IL4RPep-1-labeled, branched-type polyethyleneimine nanoparticles containing Bcl-xL siRNA more efficiently knocked down Bcl-xL expression and showed higher cytotoxic effect on cancer cells over-expressing IL4R than cancer cells expressing IL4R at low levels. These results suggest that IL4RPep-1 could be a useful probe for affinity-based imaging and drug delivery to tumor that over-expressing IL4R. Citation Format: Guruprasath Padmanaban, Sri Murugan Poongkavithai Vadevoo, Lianhua Chi, Byung-Heon Lee. IL-4 receptor-targeted delivery of liposomal doxorubicin and siRNA to tumor. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A47. doi:10.1158/1538-7445.CHTME14-A47

Production of mouse monoclonal antibody against Streptococcus dysgalactiae GapC protein and mapping its conserved B-cell epitope

Streptococcus dysgalactiae (S. dysgalactiae) GapC protein is a protective antigen that induces partial immunity against S. dysgalactiae infection in animals. To identify the conserved B-cell epitope of S. dysgalactiae GapC, a mouse monoclonal antibody 1E11 (mAb1E11) against GapC was generated and used to screen a phage-displayed 12-mer random peptide library (Ph.D.-12). Eleven positive clones recognized by mAb1E11 were identified, most of which matched the consensus motif TGFFAKK. Sequence of the motif exactly matched amino acids 97–103 of the S. dysgalactiae GapC. In addition, the epitope 97TGFFAKK103 showed high homology among different streptococcus species. Site-directed mutagenic analysis further confirmed that residues G98, F99, F100 and K103 formed the core of 97TGFFAKK103, and this core motif was the minimal determinant of the B-cell epitope recognized by the mAb1E11. Collectively, the identification of conserved B-cell epitope within S. dysgalactiae GapC highlights the possibility of developing the epitope-based vaccine.

Screening for serum biomarkers in patients with chronic hepatitis B with hepatitis B surface antigen seroclearance, following pegylated interferon alpha therapy.

Chronic hepatitis B (CHB) is one of the most common infectious disease worldwide and a leading cause of death. Hepatitis B surface antigen (HBsAg) has previously been proven to be a steady biomarker that may be used to predict clinical outcomes. The amount of circulating HBsAg has been reported to reflect the number of infected hepatocytes. An advantage of pegylated interferon alpha (peg-IFN-α) is that as a finite course of therapy, it can potentially lead to sustained disease remission in subsequent decades. HBsAg seroclearance can reportedly be achieved in some hepatitis B patients treated with peg-IFN-α; this is a major advantage of IFN-α, as compared with nucleoside analogue treatment. In the present study, a random phage display peptide library was used to screen for potential serum peptide biomarkers in predicting which patients with CHB would exhibit HBsAg seroclearance, following 48 weeks of peg-IFN-α therapy. A total of 30 patients with CHB who achieved HBsAg seroclearance following peg-IFN-α therapy and an additional 30 age-, gender-, hepatitis B e antigen (HBeAg) status- and hepatitis B virus genotype-matched patients with CHB without HBsAg seroclearance following peg-IFN-α therapy, were enrolled as a discovery cohort. In the discovery/screening phase, 17/20 of the randomly selected phage clones, exhibited a specific reaction with purified sera immunoglobulin G from the HBsAg clearance group, and 13/17 positive phage clones came from the same phage clone, with the inserted peptide sequence ETCRASCINESA (named IFNC1). In the validation phase, phage-ELISA results showed that the positive reaction rate of the IFNC1 peptide phage clone was 92.0% with the HBsAg seroclearance group (n=50), which was significantly higher, as compared with the randomly selected HBsAg non-clearance group (12.0%, n=50) and the healthy control group (8.0%, n=50). In conclusion, the newly identified mimic peptide IFNC1 showed a high predictive validity HBsAg seroclearance in patients with CHB, following peg-IFN-α therapy. Therefore IFNC1 may be a potential serum biomarker, which could be used to predict the treatment outcomes of peg-IFN-α therapy.

Abstract 4475: IL-4 receptor-targeted delivery of liposomal doxorubicin and siRNA to tumor

Abstract Targeted delivery of imaging agents and therapeutics to tumors would provide early detection and increased therapeutic efficacy against cancer. Using phage displayed-random peptide libraries, we have identified IL4RPep-1 (IL-4 receptor-binding peptide-1), CRKRLDRNC, that binds to IL-4 receptor (IL4R). IL4R is over-expressed on many types of cancer cells including lung cancer and breast cancer. Peptides have smaller size and in turn may exert better tissue penetration than bulky antibodies. IL4RPep-1 bound to H226 lung tumor cells that over-express IL4R, while little binding was observed in H460 lung tumor cells that express IL4R at low levels. When injected intravenously into nude mice bearing a subcutaneous H226 tumor, Cy7.5 near-infrared fluorescence (NIRF) dye-conjugated IL4RPep-1 selectively homed to tumor. IL4RPep-1-labeled liposomes containing doxorubicin showed more efficient anti-tumor growth activity than untargeted liposomes. In addition, IL4RPep-1-labeled, branched-type polyethyleneimine nanoparticles containing Bcl-xL siRNA more efficiently knocked down Bcl-xL expression and showed higher cytotoxic effect on cancer cells over-expressing IL4R than cancer cells expressing IL4R at low levels. These results suggest that IL4RPep-1 could be a useful probe for affinity-based imaging and drug delivery to tumor that over-expressing IL4R. Citation Format: Poongkavithai Vadevoo Sri Murugan, Gunassekaran Gowri Rangaswamy, Lianhua Chi, Guruprasath Padmanaban, Moon-Chang Baek, In-San Kim, Rang-Woon Park, Byung-Heon Lee. IL-4 receptor-targeted delivery of liposomal doxorubicin and siRNA to tumor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4475. doi:10.1158/1538-7445.AM2014-4475

Abstract 1814: Harnessing the potential of idiotypic peptide therapy for the treatment of multiple myeloma

Abstract BACKGROUND: The idiotype determinant of surface Immunoglobulin B-Cell Receptor (IgBCR) is the most reliable clonal marker of tumor cell population and can be exploited for novel targeting approaches. We previously developed a novel experimental approach to identify peptide ligands of the IgBCR idiotype determinant of neoplastic B cells, named “Id-peptides” (Palmieri C., Blood 2010). These Id-peptides were validated as a tool for specific targeting of B-cell malignancies with a potential role as modulators of tumor microenvironment via sIgBCR signalling. In Multiple Myeloma (MM), both mature and clonogenic tumor stem cells (clonotype B-lymphocytes, CBLs) share the same antigenic specificity, making these cells a suitable target for Id-peptides. In this regard, we have recently developed Id-peptides for tumor targeting in primary neoplastic plasma cells as well as in the 5T33MM mouse model of MM. RESULTS: Tumor-specific Id-peptides of MM (n=8), or MGUS (n=2) patients were selected by screening phage-displayed random peptide libraries using the cognate serum IgG paraprotein as bait. The selected Id-peptides specifically bound to the cognate primary neoplastic plasma cells, as shown by FACS analysis. By confocal microscopy, we observed that each patient-specific Id-peptide co-localized with the sIgG-BCR at the cell surface of the cognate neoplastic plasma cell. Further, the Id-peptides were able to target CD138pos differentiated plasma cells as well as a number of less differentiated CD138neg, IgGpos and CD19pos bone marrow B-cells, suggesting that they tracked the clonogenic precursors of MM cells. Using the same screening approach in the 5T33MM mouse model of MM, Id-peptides were able to specifically detect a significant proportion of target cancer cells in the peripheral blood of diseased animal. Interestingly, the in vivo exposure of 5T33 murine MM cells to Id-peptides resulted in a reduced expression of immunosuppressive cytokines genes (Tgfb1 and Il10) and pro-angiogenic genes (Vegf, Tbxas, SDF, Il8, CXCr4). CONCLUSION: This study demonstrates that Id-peptides can be used to identify and purify the clonotypic precursors of MM cells, thus providing a unique tool for assessing both the phenotypic and functional features of the still poorly characterized MM “cancer stem cell” compartment. Moreover, the Id-peptides can inhibit the expression of genes that are crucial to promote a functional MM microenvironment and angiogenesis, thus representing a potential tool for MM therapy. Note: This abstract was not presented at the meeting. Citation Format: Enrico Iaccino, Selena Mimmi, Cristina Falcone, Eleonora Vecchio, Roberta Crescenzo, Giuseppina Maggisano, Cesare Carvelli, Samuela Russo, Annamaria de Laurentiis, Marilena Pontoriero, Antonio Pisano, Simona Ceglia, Francesca Fasanella Masci, Annarita Scialdone, Annalisa Rossi, Giuseppe Fiume, Camillo Palmieri, Ileana Quinto, Giuseppe Scala. Harnessing the potential of idiotypic peptide therapy for the treatment of multiple myeloma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1814. doi:10.1158/1538-7445.AM2014-1814

Screening and identification of C7C peptide ligands of Mycobacterium tuberculosis

To obtain the C7C peptide ligands of Mycobacterium tuberculosis by affinity screening based on the phage-displayed random C7C peptide library, and preliminarily identify the binding capacity of the peptide to Mycobacterium. Inactive Mycobacterium tuberculosis reference strain H37Rv was used as the target molecule to screen the Ph. D.-C7C peptide library, and Mycobacterium bovis, BCG was used for reverse screening. After 4 rounds of affinity screening, single phages eluted by H37Rv and BCG were selected for DNA sequencing. ELISA was used to detect the binding affinities of different single phage clones. The cyclic peptides displayed by the phage clones showing the highest appetency were synthesized in vitro with fluorescent markers. Fluorescence microscopy and flow cytometer was used to detect the binding affinities of synthesized cyclic peptides, comparing with linear binding peptides obtained before. After 4 rounds of biopanning, phages that could bind with target molecules were remarkable enriched. 16 common sequences were obtained by sequencing analysis of single phages. With ELISA, phage SB1, SB5, SB8 and SB26 all showed higher affinity with H37Rv and BCG, the ratio to negative control of which were ≥ 2.1, but could not bind to the 3 nonmycobacteria, which were identified as the positive clones. Based on the results of flow cytometer detection, the affinities to H37Rv of 4 cyclic peptides SB1, SB5, SB24, SB26 were (73.2 ± 6.3)%, (63.2 ± 5.3)%, (32.9 ± 3.1)%, (89.4 ± 7.0)%, and to BCG were (65.6 ± 6.1)%, (48.6 ± 4.5)%, (10.3 ± 1.8)%, (86.6 ± 7.9)%, separately, which were all higher than H8 ((4.0 ± 1.0)%, (5.5 ± 1.2)%) . From the results of fluorescence microscopy observation, all of the fluorescent labeled cyclic peptides SB1, SB5, SB24, SB26 could bind to H37Rv and showed higher fluorescence intensities, which also had certain affinities to other 18 mycobacteria, but the fluorescence intensities were lower than H37Rv, and didn't bind to 3 non-mycobacteria. Based on the replacement of linear 7 peptide library with C7C peptide library, new ligands of Mycobacterium tuberculosis were achieved successfully, which showed significantly higher binding affinities to mycobacteria.