Binding motifs of CBP2 a potential cell surface target for carcinoma cells

Previously we have shown (Hebert et al. [1999] J. Cell Biochem. 73:248-258) that among many cell lines the CBP2 gene product, Hsp47, eludes its retent ion receptor, erd2P, resulting in the appearance of Hsp47 on the cell surfa ce associated with the tetraspanin protein CD9. Since Hsp47 possesses a hig hly restricted binding cleft, random peptide display libraries were used to characterize peptides binding to Hsp47 and then to target this protein on carcinoma cell lines in vitro. Comparison of the clones obtained from panni ng revealed little specific homology based on sequence alone. To determine whether carcinoma cells expressing Hsp47 could selectively take up the sele cted bacteriophages, traditional immunofluorescence and confocal microscopy were employed. These studies revealed that phage-displaying Hsp47 binding peptides bound to cell lines expressing Hsp47 and that the peptides were ra pidly taken up to a location coincident with Hsp47 staining. These observat ions were confirmed by cytometric analyses. These data indicate that CBP2 p roduct may provide a molecular target for chemotherapy and/or imaging of ma lignancies. (C) 2000 Wiley-Liss, Inc.