Identification of Transmembrane Protein in Prostate Cancer by the Escherichia coli Ampicillin Secretion Trap: Expression of CDON Is Involved in Tumor Cell Growth and Invasion

• Published in: Pathobiology (Basel) Vol. 78; no. 5; pp. 277 - 284
• Main Authors: Hayashi, Tetsutaro, Oue, Naohide, Sakamoto, Naoya, Anami, Katsuhiro, Oo, Htoo Zarni, Sentani, Kazuhiro, Ohara, Shinya, Teishima, Jun, Matsubara, Akio, Yasui, Wataru
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland S. Karger AG 01.09.2011
• Subjects: Ampicillin; Anti-Bacterial Agents; Biomarkers, Tumor - analysis; Blotting, Western; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Cell growth; E coli; Escherichia coli; Gene Expression Profiling; Gene Library; Genetic Techniques; Humans; Male; Membranes; Neoplasm Invasiveness - genetics; Neoplasm Invasiveness - pathology; Original Paper; Prostate cancer; Prostatic Neoplasms - genetics; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Proteins; Real-Time Polymerase Chain Reaction; Tumor Suppressor Proteins - genetics; Tumor Suppressor Proteins - metabolism; Tumors; Prostate cancer; Escherichia coli ampicillin secretion trap; CDON
• DOI: 10.1159/000329588
• ISSN: 1015-2008

Aims: Prostate cancer (PCa) is one of the most common malignancies worldwide. Genes expressed only in cancer tissue, and especially related to proteins located on the cell membrane, will be useful molecular markers for diagnosis and may also be good therapeutic targets. The aim of this study was to identify genes that encode transmembrane proteins present in PCa. Methods and Results: We generated Escherichia coli ampicillin secretion trap (CAST) libraries from 2 PCa cell lines and normal prostate tissues. By sequencing 3,264 colonies from CAST libraries, we identified 18 candidate genes that encode transmembrane proteins present in PCa. Quantitative RT-PCR analysis of these candidates revealed that STEAP1, ADAM9 and CDON were expressed much more highly in PCa than in 15 kinds of normal tissues. Among the candidates, CDON encodes the CDO protein, which is an orphan cell surface receptor of the immunoglobulin superfamily. Additional quantitative RT-PCR revealed that 83% of PCa tissues showed CDON overexpression. Knockdown of CDON in DU145 cells induced 5-fluorouracil-induced apoptosis and inhibited invasion ability. Conclusion: These results suggest that CDON has a high potential as a therapeutic target for PCa.