title: Identification of a novel cell binding site of periostin involved in tumour growth.
abstract: BACKGROUND
  Periostin (PN), a member of the fasciclin family of proteins, is a TGF-β-induced extracellular matrix protein involved in cell survival, angiogenesis, invasion and metastasis. It is considered a potent angiogenic factor and a marker of tumour progression in many types of human cancer. Many different kinds of cells bind to PN by means of the integrins αvβ3 and αvβ5, but the periostin epitope recognised by these integrins is not formally demonstrated. The aim of our study was to identify which domain of PN could be involved in cell adhesion and its potential role in tumour growth.
  
  
  METHODS
  We generated the monoclonal antibody OC-20 (mAb OC-20) by hybridoma technology. Different PN recombinant fragments were used to characterise the periostin epitope recognised by the mAb OC-20 and to localise a new cell binding site of the protein. A murine model of human melanoma was used in the preclinical in vivo experiments.
  
  
  RESULTS
  We formally demonstrate that the periostin epitope recognised by OC-20 is a new binding site for the integrins αvβ3 and αvβ5, localised in the second FAS1 domain (FAS1-2) of the protein. Moreover the in vivo use of this antibody significantly inhibits tumour growth and angiogenesis.
  
  
  CONCLUSIONS
  Our results show that the FAS1-2 domain of PN plays a role in tumour progression. Moreover this novel antibody may likewise prove to be very useful in clarifying the role of PN in angiogenesis and may contribute to the design of novel anti-angiogenesis drugs.
authors: Laboratory of Immunology, Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy.
authors: Paola
authors: P
authors: Orecchia
authors: Romana
authors: R
authors: Conte
authors: Enrica
authors: E
authors: Balza
authors: Patrizia
authors: P
authors: Castellani
authors: Laura
authors: L
authors: Borsi
authors: Luciano
authors: L
authors: Zardi
authors: Maria Cristina
authors: MC
authors: Mingari
authors: Barbara
authors: B
authors: Carnemolla