title: A novel human fibronectin cryptic sequence unmasked by the insertion of the angiogenesis-associated extra type III domain B.
abstract: The angiogenesis-associated extra-domain B (EDB) of fibronectin (FN) is a complete type III repeat of 91 amino acids. Its expression is modulated by the alternative splicing pattern of the FN pre-mRNA. FN containing the EDB (B-FN) is undetectable in tissues of healthy adults, with rare exceptions such as the female reproductive system where tissue remodeling and angiogenesis are recurrent physiological processes. On the contrary, B-FN is expressed at high levels in neoplastic tissues and during angiogenesis; consequently, it is considered an excellent marker of angiogenesis. Here, we report on a novel FN cryptic sequence, localized on the FN type III repeat 8 (immediately downstream of the EDB) that is unmasked by the insertion of the EDB. This sequence is specifically recognized by the high-affinity monoclonal antibody, C6, that selectively recognizes B-FN by means of ELISA, immunohistochemical and Western blot assays. The variable regions of C6 were cloned and a divalent covalently linked mini-antibody was generated. Biodistribution studies using the radioiodinated C6 mini-antibody on tumor-bearing mice demonstrated an efficient tumor targeting. This antibody represents a new tool for the study of the potential biological functions of hindered sequences that the inclusion of the EDB renders accessible, and likewise makes its epitope an additional angiogenesis target.
authors.affiliation: Laboratory of Cell Biology, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
authors.forename: Enrica
authors.initials: E
authors.lastname: Balza
authors.forename: Francesca
authors.initials: F
authors.lastname: Sassi
authors.forename: Elisa
authors.initials: E
authors.lastname: Ventura
authors.forename: Arianna
authors.initials: A
authors.lastname: Parodi
authors.forename: Sara
authors.initials: S
authors.lastname: Fossati
authors.forename: William
authors.initials: W
authors.lastname: Blalock
authors.forename: Barbara
authors.initials: B
authors.lastname: Carnemolla
authors.forename: Patrizia
authors.initials: P
authors.lastname: Castellani
authors.forename: Luciano
authors.initials: L
authors.lastname: Zardi
authors.forename: Laura
authors.initials: L
authors.lastname: Borsi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004797:Enzyme-Linked Immunosorbent Assay; D005353:Fibronectins / Q000737:chemistry / Q000378:metabolism*; D054879:Halogenation; D006801:Humans; D007124:Immunoenzyme Techniques; D051379:Mice; D016513:Mice, SCID; D009369:Neoplasms / Q000378:metabolism*; D009374:Neoplasms, Experimental / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014598:Uteroglobin / Q000276:immunology / Q000378:metabolism
chemical_list: D005353:Fibronectins; D011993:Recombinant Fusion Proteins; D014598:Uteroglobin