Protocadherin B9 Is Associated with Tumorigenesis and Cancer Progression in Colorectal Cancer

Abstract

<b><i>Background:</i></b> Genes encoding transmembrane proteins expressed specifically in cancer cells may be ideal therapeutic targets or biomarkers for diagnosis. <b><i>Methods:</i></b> In the present study, we investigated the expression and function of <i>PCDHB9</i>, which encodes transmembrane protein protocadherin B9 in colorectal cancer (CRC). <b><i>Results:</i></b> Immunohistochemical analysis showed that 39 (26%) of 148 CRC cases were positive for protocadherin B9. Expression of protocadherin B9 correlated with lymphatic invasion, venous invasion, and T classification and was weakly detected in adenomas by immunohistochemistry. Although <i>PCDHB9</i> knockdown did not change cell growth and invasion activity in CRC cell lines, cell adhesion to fibronectin was significantly reduced by <i>PCDHB9</i> knockdown. Expressions of <i>ITGA3</i>, <i>ITGA4</i>, <i>ITGA5, ITGB1</i>, and <i>ITGB6</i> were significantly reduced by <i>PCDHB9</i> knockdown. In addition, the number of spheres was significantly decreased by <i>PCDHB9</i> knockdown. <b><i>Conclusion:</i></b> These results suggest that protocadherin B9 might be associated with colorectal tumorigenesis and cancer progression in CRC.