title: A tumor-associated fibronectin isoform generated by alternative splicing of messenger RNA precursors.
abstract: Fibronectin (FN) represents the mixture of a number of structurally different molecules (isoforms) whose make-up varies depending on the FN sources. FN from cultured transformed human cells has a very different isoform composition with respect to its normal counterpart. In fact, SV-40-transformed WI-38VAI3 human fibroblasts produce high levels of a FN isoform (B-FN) which is very poorly expressed in their normal, WI-38, counterpart. We have recently demonstrated that the B-FN isoform derives from a differential splicing pattern of the FN primary transcript which leads, in transformed cells, to a high level expression of the exon ED-B (Zardi, L., B. Carnemolla, A. Siri, T. E. Petersen, G. Paolella, G. Sebastio, and F. E. Baralle. 1987. EMBO (Eur. Mol. Biol. Organ.) J. 6:2337-2342). Here we report on the production and characterization of a monoclonal antibody (BC-1) which recognizes an epitope within the protein sequence coded for by the ED-B exon. This monoclonal antibody makes it possible to carry out immunohistochemical analysis of the distribution of the ED-B-containing FN isoform (B-FN) in human tissues. The results show that while in normal, adult, human tissues total FN has a widespread distribution, the B-FN isoform is restricted only to synovial cells, to some vessels and areas of the interstitium of the ovary, and to the myometrium. On the contrary, the B-FN isoform has a much greater expression in fetal and tumor tissues. These results demonstrate that, in vivo, different FN isoforms have a differential distribution and indicate that the B-FN isoform may play a role in ontogenesis and oncogenetic processes.
authors.affiliation: Cell Biology Laboratory, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Carnemolla
authors.forename: E
authors.initials: E
authors.lastname: Balza
authors.forename: A
authors.initials: A
authors.lastname: Siri
authors.forename: L
authors.initials: L
authors.lastname: Zardi
authors.forename: M R
authors.initials: MR
authors.lastname: Nicotra
authors.forename: A
authors.initials: A
authors.lastname: Bigotti
authors.forename: P G
authors.initials: PG
authors.lastname: Natali
mesh_terms: D000911:Antibodies, Monoclonal; D002460:Cell Line; D005091:Exons; D005260:Female; D005333:Fetus / Q000032:analysis*; D005353:Fibronectins / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques; D009215:Myometrium / Q000032:analysis; D009369:Neoplasms / Q000032:analysis*; D010053:Ovary / Q000032:analysis; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D013583:Synovial Membrane / Q000032:analysis
chemical_list: D000911:Antibodies, Monoclonal; D005353:Fibronectins; D012322:RNA Precursors