ED-B fibronectin expression is a marker of epithelial-mesenchymal transition in translational oncology

// Iacopo Petrini 1 , Serena Barachini 2 , Vittoria Carnicelli 3 , Sara Galimberti 2 , Letizia Modeo 4 , Roberto Boni 4 , Martina Sollini 5 , Paola Anna Erba 4 1 General Pathology, Department of Translational Research and New Technology in Medicine, University of Pisa, Pisa, Italy 2 Laboratory of Hematology, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy 3 Biochemistry, Department of Translational Research and New Technology in Medicine, University of Pisa, Pisa, Italy 4 Nuclear Medicine, Department of Translational Research and New Technology in Medicine, University of Pisa, Pisa, Italy 5 Department of Biomedical Sciences, Humanitas University, Rozzano, Milan, Italy Correspondence to: Iacopo Petrini, email: iacopo.petrini@unipi.it Keywords: fibronectin, endothelial-to-mesenchymal transition, ED-B, prostate cancer, TGF-β Received: July 25, 2016      Accepted: November 09, 2016      Published: November 25, 2016 ABSTRACT Fibronectin is a component of the extracellular matrix that links collagen fibers to integrins on the cell’s surface. The splicing isoforms, containing the ED-B domain, are not expressed in adult tissues but only in tumor stroma or during embryonic development. Fibroblasts and endothelial cells express ED-B fibronectin during angiogenesis. Also cancer cells can synthetize ED-B fibronectin, but its function in tumor growth needs to be further elucidated. We evaluated the expression of ED-B fibronectin in prostate cancer cell lines: PC3 and DU145. Using TGF-β, we induced epithelial to mesenchymal transition in culture and observed an increase of ED-B fibronectin expression. Thereafter, we evaluated the expression of ED-B fibronectin in multipotent mesangiogenic progenitor cells, and in mesenchymal stromal cells. The expression of ED-B fibronectin was much higher in mesenchymal than prostate cancer cells even after the epithelial to mesenchymal transition. Epithelial to mesenchymal transition is a key step for tumor progression contributing to the metastatic spread. Therefore, circulating cancer cells could seed into the metastatic niche taking advantage from the ED-B fibronectin that secrete their own.