DBC1/CCAR2 is involved in the stabilization of androgen receptor and the progression of osteosarcoma

Deleted in breast cancer 1 (DBC1/CCAR2) is a protein of interest because of its diverse roles in tumorigenesis and its possible role as an androgen receptor (AR) co-activator. However, there are limited studies on the role of DBC1 in osteosarcoma. Therefore, we investigated the role of DBC1 and AR and their relationship in osteosarcoma. Immunohistochemical expression of DBC1 and AR was significantly associated with higher clinical stage and higher histologic grade, and predicted shorter survival. Especially, DBC1 expression was an independent prognostic indicator of overall survival (p = 0.005) and relapse-free survival (p = 0.004) by multivariate analysis. In osteosarcoma cell lines, U2OS and SaOS2, the knock down of DBC1 and AR with siRNA significantly reduced cellular proliferation and inhibited proliferation-related signaling. In addition, the knock down of DBC1 and AR decreased the invasion activity and inhibited invasion-related signaling of osteosarcoma cells. Interestingly, DBC1 affects the stabilization of AR protein via a mechanism involving the ubiquitination of AR. Proteosome-mediated degradation and poly-ubiquitination of AR were increased with the knock-down of DBC1. In conclusion, this study has shown that DBC1 is involved in the stabilization of AR protein and DBC1-AR pathways might be involved in the progression of osteosarcoma.