Regulation of β-Catenin Phosphorylation by PR55β in Adenoid Cystic Carcinoma.

Abstract

Adenoid cystic carcinoma (AdCC) is a rare cancer of the salivary gland with high risk of recurrence and metastasis. Wnt signalling is critical for determining tumor grade in AdCC, as it regulates invasion and migration. β-catenin dephosphorylation plays an important role in the Wnt pathway, but its underlying molecular mechanism remains unclear. Because the regulatory subunits of protein phosphatase 2A (PP2A) drive Wnt signalling via target molecules, including β-catenin, we used qRT-PCR and immunoblot analysis to investigate the expression of these subunits in an AdCC cell line (ACCS) and a more aggressive subline (ACCS-M). PR55β was highly expressed in ACCS-M, suggesting its functional importance. In addition, PR55β expression was associated with tumor grade, with ACCS-M exhibiting higher PR55β levels. More importantly, knockdown of PR55β in ACCS-M cells significantly reduced invasiveness and metastatic ability. Furthermore, dephosphorylation and total levels of β-catenin were dependent on PR55β in ACCS-M. Finally, we confirmed a correlation between PR55β staining intensity and histopathological type in human AdCC tissues. Our study provides new insight into the interaction between PR55β and β-catenin and suggests that PR55β may be a target for the clinical treatment of AdCC.