Oligophrenin-1 is associated with cell adhesion and migration in prostate cancer

We performed Escherichia coli ampicillin secretion trap (CAST) analysis in prostate cancer (PCa) to identify novel biomarkers. We show here that OPHN1, which encodes oligophrenin-1 protein, is upregulated in PCa. OPHN1 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.

We investigate the expression of oligophrenin-1 in 141 PCa tissue samples by immunohistochemistry and perform functional analysis using RNA interference.

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 OPHN1 small interfering (si)RNA-transfected LNCaP and PC3 cells in comparison to negative-control siRNA-transfected cells. Knockdown of OPHN1 reduced the expression of ITGA5 and stress fiber formation in LNCaP and PC3 cells.

These results suggest that oligophrenin-1 is involved in tumor progression in PCa.