In-site interaction evaluation of Tn density by inhibition/competition assays

• Published in: Nuclear medicine and biology Vol. 37; no. 4; pp. 453 - 458
• Main Authors: Robles, Ana, Medeiros, Andrea, Berois, Nora, Balter, Henia S, Pauwels, Ernest K, Osinaga, Eduardo
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-05-2010; Elsevier
• Subjects: Amino Acid Sequence; Antibodies, Monoclonal - immunology; Antibody Specificity; Antigen-antibody reactions, antigen-antibody complexes, antibody-complement and others. Study of affinity. Antigen presentation; Antigens, Tumor-Associated, Carbohydrate - immunology; Antigens, Tumor-Associated, Carbohydrate - metabolism; Binding Sites; Binding, Competitive; Biological and medical sciences; Epitopes - immunology; Fundamental and applied biological sciences. Psychology; Fundamental immunology; In-site interaction; Inhibition/competition assays; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Miscellaneous. Technology; Molecular immunology; Oligopeptides - chemistry; Oligopeptides - pharmacology; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Plant Lectins - chemistry; Plant Lectins - immunology; Radioimmunoassay; Radiology; Tn density; Vicia; Inhibition/competition assays; Tn density; In-site interaction; Nuclear medicine; Tumor associated antigen; Antigenic determinant; Peptides; Vicia villosa; Rodentia; Tumoral marker; Binding site; Monoclonal antibody; Assay; Vertebrata; Mammalia; Leguminosae; Mouse; Dicotyledones; Animal; Radioimmunoassay; Angiospermae; Spermatophyta; Biomedical engineering
• ISSN: 0969-8051; 1872-9614
• DOI: 10.1016/j.nucmedbio.2009.10.009

Abstract The tumor-associated structure N -acetyl-galactosamine-O-Ser/Thr (Tn antigen), which is overexpressed in various tumor cell types, notably of the breast, ovary and colon, is an interesting determinant that is useful for cancer diagnosis and follow-up. The aim of this research was to study different assay strategies in order to determine the most sensitive system for further application in epitope characterization and binding assessment. The tetrameric isolectin obtained from Vicia villosa seeds (VVLB4 ) shows high affinity for the tumor-associated structure. A monoclonal antibody against VVLB4 , MabVV34 , was generated, and the interaction between MabVV34 and VVLB4 was studied by means of binding and inhibition assays. Several synthetic peptides (10 amino acid sequences) designed from the amino acid sequence of VVLB4 and obtained from trypsin digestion were tested to determine which amino acids were involved in the interaction between MabVV34 and VVLB4 . The further unraveling of this epitope was investigated by inhibition using designed synthetic peptides as well as mixtures mimicking variable density effect. Under the experimental circumstances, MabVV34 was able to inhibit the binding of VVLB4 to Tn. Two of the four peptide sequences assayed showed better inhibition properties. Finally, mixtures containing these selected sequences allowed the evaluation of binding and inhibition as a function of Tn density. We conclude that the present study facilitates the further development of a specific Tn marker and may contribute to the development of Tn-like radiolabelled peptides or Tn-specific radiolabelled fragments providing a highly selective tool for cancer diagnosis and treatment. This strategy may contribute to characterize the new generation of radiopharmaceuticals for diagnosis and therapy based on biomolecules like antibodies, fragments or peptides, whose application is directly guided by their specific molecular recognition.