Supplementary Material for: Oligophrenin-1 Is Associated with Cell Adhesion and Migration in Prostate Cancer

<b><i>Objective:</i></b> We performed <i>Escherichia coli</i> ampicillin secretion trap (CAST) analysis in prostate cancer (PCa) to identify novel biomarkers. We show here that <i>OPHN1</i>, which encodes oligophrenin-1 protein, is upregulated in PCa. <i>OPHN1</i> was first determined to be one of the genes associated with X-linked mental retardation; however, neither the gene's function nor the link between its expression and survival of patients has been investigated. <b><i>Methods:</i></b> We investigate the expression of oligophrenin-1 in 141 PCa tissue samples by immunohistochemistry and perform functional analysis using RNA interference. <b><i>Results:</i></b> Immunohistochemical analysis of oligophrenin-1 demonstrated that 60 (43%) PCa cases were positive for oligophrenin-1. Positive oligophrenin-1 expression was significantly correlated with a high Gleason score (p = 0.0198). Furthermore, patients with oligophrenin-1-positive PCa had a worse biochemical recurrence-free survival rate than patients with oligophrenin-1-negative PCa (p = 0.0079). Cell adhesion to fibronectin was significantly reduced in <i>OPHN1</i> small interfering (si)RNA-transfected LNCaP and PC3 cells in comparison to negative-control siRNA-transfected cells. Knockdown of <i>OPHN1</i> reduced the expression of <i>ITGA5 </i>and stress fiber formation in LNCaP and PC3 cells. <b><i>Conclusion:</i></b> These results suggest that oligophrenin-1 is involved in tumor progression in PCa.